WorldWideScience

Sample records for extratropical tropopause region

  1. A meridional structure of static stability and ozone vertical gradient around the tropopause in the Southern Hemisphere extratropics

    Directory of Open Access Journals (Sweden)

    Y. Tomikawa

    2010-08-01

    Full Text Available An analysis of the static stability and ozone vertical gradient in the ozone tropopause based (OTB coordinate is applied to the ozonesonde data at 10 stations in the Southern Hemisphere (SH extratropics. The tropopause inversion layer (TIL with a static stability maximum just above the tropopause shows similar seasonal variations at two Antarctic stations, which are latitudinally far from each other. Since the sunshine hour varies with time in a quite different way between these two stations, it implies that the radiative heating due to solar ultraviolet absorption of ozone does not contribute to the seasonal variation of the TIL. A meridional section of the static stability in the OTB coordinate shows that the static stability just above the tropopause has a large latitudinal gradient between 60° S and 70° S in austral winter because of the absence of the TIL over the Antarctic. It is accompanied by an increase of westerly shear with height above the tropopause, so that the polar-night jet is formed above this latitude region. This result suggests a close relationship between the absence of the TIL and the stratospheric polar vortex in the Antarctic winter. A vertical gradient of ozone mixing ratio, referred to as ozone vertical gradient, around the tropopause shows similar latitudinal and seasonal variations with the static stability in the SH extratropics. In a height region above the TIL, a small ozone vertical gradient in the midlatitudes associated with the Antarctic ozone hole is observed in a height region of the subvortex but not around the polar vortex. This is a clear evidence of active latitudinal mixing between the midlatitudes and subvortex.

  2. Baroclinic mixing of potential vorticity as the principal sharpening mechanism for the extratropical Tropopause Inversion Layer

    Science.gov (United States)

    Wang, Shu Meir; Geller, Marvin A.

    2016-09-01

    Previous works have shown that a dry, idealized general circulation model could produce many features of the extratropical Tropopause Inversion Layer (TIL). In particular, the following have been shown, but no explanations were given for these results. (1) A sharper extratropical TIL resulted more from increased horizontal resolution than from increased vertical resolution. (2) If the Equator-to-Pole temperature gradient was varied, the annual variation of the extratropical TIL found in observations could be reproduced. (3) The extratropical TIL altitude showed excellent correlation with the upper tropospheric relative vorticity, as had been previously proposed. (4) Increased horizontal model resolutions led to extratropical TILs that were at lower altitudes. We show that these conclusions follow from baroclinic mixing of high stratospheric potential vorticity into the troposphere being the principal sharpening mechanism for the extratropical TIL and the increased baroclinic activity occurring in higher horizontal resolution models. We furthermore suggest that the distance from the jet exerts a greater influence on the height and sharpness of the extratropical TIL than does the upper tropospheric relative vorticity, and this accounts for the annual behavior of the extratropical TIL found in observations and reproduced with a dry, mechanistic, global model.

  3. Seasonal Ozone Variations in the Isentropic Layer between 330 and 380 K as Observed by SAGE 2: Implications of Extratropical Cross-Tropopause Transport

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    Wang, Pi-Huan; Cunnold, Derek M.; Zawodny, Joseph M.; Pierce, R. Bradley; Olson, Jennifer R.; Kent, Geoffrey S.; Skeens, Kristi, M.

    1998-01-01

    To provide observational evidence on the extratropical cross-tropopause transport between the stratosphere and the troposphere via quasi-isentropic processes in the middleworld (the part of the atmosphere in which the isentropic surfaces intersect the tropopause), this report presents an analysis of the seasonal variations of the ozone latitudinal distribution in the isentropic layer between 330 K and 380 K based on the measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II. The results from SAGE II data analysis are consistent with (1) the buildup of ozone-rich air in the extratropical middleworld through the large-scale descending mass circulation during winter, (2) the spread of ozone-rich air in the isentropic layer from midlatitudes to subtropics via quasi-isentropic transport during spring, (3) significant photochemical ozone removal and the absence of an ozone-rich supply of air to the layer during summer, and (4) air mass exchange between the subtropics and the extratropics during the summer monsoon period. Thus the SAGE II observed ozone seasonal variations in the middleworld are consistent with the existing model calculated annual cycle of the diabatic circulation as well as the conceptual role of the eddy quasi-adiabatic transport in the stratosphere-troposphere exchange reported in the literature.

  4. Lidar Observation of Tropopause Ozone Profiles in the Equatorial Region

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    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    Tropospheric ozone in the tropics zone is significant in terms of the oxidizing efficiency and greenhouse effect. However, in the upper troposphere, the ozone budget in the tropics has not been fully understood yet because of the sparsity of the range-resolved observations of vertical ozone concentration profiles. A DIAL (differential absorption lidar) system for vertical ozone profiles have been installed in the equatorial tropopause region over Kototabang, Indonesia (100.3E, 0.2S). We have observed large ozone enhancement in the upper troposphere, altitude of 13 - 17 km, concurring with a zonal wind oscillation associated with the equatorial Kelvin wave around the tropopause at equatorial region.

  5. The roles of convection, extratropical mixing, and in-situ freeze-drying in the Tropical Tropopause Layer

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    W. G. Read

    2008-10-01

    Full Text Available Mechanisms for transporting and dehydrating air across the tropical tropopause layer (TTL are investigated with a conceptual two dimensional (2-D model. The 2-D TTL model combines the Holton and Gettelman cold trap dehydration mechanism (Holton and Gettelman, 2001 with the two column convection model of Folkins and Martin (2005. We investigate 3 possible transport scenarios through the TTL: 1 slow uniform ascent across the level of zero radiative heating without direct convective mixing, 2 convective mixing of H2O vapor at 100% relative humidity with respect to ice (RHi with no ice retention, and 3 convective mixing of extremely subsaturated air (100% RHi following the moist adiabatic temperature above the level of neutral buoyancy with sufficient ice retention such that total H2O is 100%RHi. The three mechanisms produce similar seasonal cycles for H2O that are in good quantitative agreement with the Aura Microwave Limb Sounder (MLS measurements. We use Aura MLS measurement of CO and Atmospheric Chemistry Experiment-Fourier Transform Spectrometer measurement of HDO to distinguish among the transport mechanisms. Model comparisons with the observations support the view that H2O is predominantly controlled by regions having the lowest cold point tropopause temperature but the trace species CO and HDO support the convective mixing of dry air and lofted ice. The model provides some insight into the processes affecting the long term trends observed in stratospheric H2O.

  6. Processes Controlling Water Vapor in the Winter Arctic Tropopause Region

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    Pfister, Leonhard; Selkirk, Henry B.; Jensen, Eric J.; Padolske, James; Sachse, Glen; Avery, Melody; Schoeberl, Mark R.; Mahoney, Michael J.; Richard, Erik

    2002-01-01

    This work describes transport and thermodynamic processes that control water vapor near the tropopause during the SAGE III-Ozone Loss and Validation Experiment (SOLVE), held during the Arctic 1999/2000 winter season. Aircraft-based water vapor, carbon monoxide, and ozone measurements were analyzed so as to establish how deeply tropospheric air mixes into the Arctic lowermost stratosphere and what the implications are for cloud formation and water vapor removal in this region of the atmosphere. There are three major findings. First, troposphere-to-stratosphere exchange extends into the Arctic stratosphere to about 13 km. Penetration is to similar levels throughout the winter, however, because ozone increases with altitude most rapidly in the early spring, tropospheric air mixes with the highest values of ozone in that season. The effect of this upward mixing is to elevate water vapor mixing ratios significantly above their prevailing stratospheric values of above 5ppmv. Second, the potential for cloud formation in the stratosphere is highest during early spring, with about 20% of the parcels which have ozone values of 300-350 ppbv experiencing ice saturation in a given 10 day period. Third, during early spring, temperatures at the troposphere are cold enough so that 5-10% of parcels experience relative humidities above 100%, even if the water content is as low as 5 ppmv. The implication is that during this period, dynamical processes near the Arctic tropopause can dehydrate air and keep the Arctic tropopause region very dry during early spring.

  7. Characteristics of tropopause parameters as observed with GPS radio occultation

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    T. Rieckh

    2014-11-01

    Full Text Available Characteristics of the lapse rate tropopause are analyzed globally for tropopause altitude and temperature using global positioning system (GPS radio occultation (RO data from late 2001 to the end of 2013. RO profiles feature high vertical resolution and excellent quality in the upper troposphere and lower stratosphere, which are key factors for tropopause determination, including multiple ones. RO data provide measurements globally and allow examination of both temporal and spatial tropopause characteristics based entirely on observational measurements. To investigate latitudinal and longitudinal tropopause characteristics, the mean annual cycle, and inter-annual variability, we use tropopauses from individual profiles as well as their statistical measures for zonal bands and 5° × 10° bins. The latitudinal structure of first tropopauses shows the well-known distribution with high (cold tropical tropopauses and low (warm extra-tropical tropopauses. In the transition zones (20 to 40° N/S, individual profiles reveal varying tropopause altitudes from less than 7 km to more than 17 km due to variability in the subtropical tropopause break. In this region, we also find multiple tropopauses throughout the year. Longitudinal variability is strongest at northern hemispheric mid latitudes and in the Asian monsoon region. The mean annual cycle features changes in amplitude and phase, depending on latitude. This is caused by different underlying physical processes (such as the Brewer–Dobson circulation – BDC and atmospheric dynamics (such as the strong polar vortex in the southern hemispheric winter. Inter-annual anomalies of tropopause parameters show signatures of El Niño–Southern Oscillation (ENSO, the quasi–biennial oscillation (QBO, and the varying strength of the polar vortex, including sudden stratospheric warming (SSW events. These results are in good agreement with previous studies and underpin the high utility of the entire RO record

  8. Statistics of the Tropopause Inversion Layer over Beijing

    Institute of Scientific and Technical Information of China (English)

    BIAN Jianchun; CHEN Hongbin

    2008-01-01

    High resolution radiosonde data from Beijing, China in 2002 are used to study the strong tropopause inversion layer (TIL) in the extratropical regions in eastern Asia. The analysis, based on the tropopause-based mean (TB-mean) method, shows that the TIL over Beijing has similar features as over other sites in the same latitude in Northern America. The reduced values of buoyancy frequency in 13-17 km altitude in winter-spring are attributed to the higher occurrence frequency of the secondary tropopause in this season. In the monthly mean temperature profile relative to the secondary tropopause, there also exists a TIL with somewhat enhanced static stability directly over the secondary sharp thermal tropopause, and a 4 km thickness layer with reduced values of buoyancy frequency just below the tropopause, which corresponds to the 13-17 km layer in the first TB-mean thermal profile. In the monthly mean temperature profile relative to the secondary tropopause, a TIL also exists but it is not as strong. For individual cases, a modified definition of the TIL, focusing on the super stability and the small distance from the tropopause, is introduced. The analysis shows that the lower boundary of the newly defined TIL is about 0.42 km above the tropopause, and that it is higher in winter and lower in summer; the thickness of the TIL is larger in winter-spring.

  9. On the structure of the extra-tropical transition layer from in-situ observations

    OpenAIRE

    Pisso, I.; Law, K. S.; Fierli, F.; P. H. Haynes; P. Hoor; Palazzi, E; F. Ravegnani; S. Viciani

    2012-01-01

    In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994–2007 were combined to investigate the Extra-tropical Transition Layer (ExTL) region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces...

  10. On the composition and optical extinction of particles in the tropopause region

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Wessling (Germany). Inst. fuer Physik der Atmosphaere; Solomon, S. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Aeronomy Lab.

    1999-06-01

    Liquid aerosol particles and ice crystals in subvisible cirrus clouds in the tropopause region are characterized in terms of size distributions, chemical composition, and optical extinction. These particle properties are studied by means of simple models and are related to satellite extinction measurements, particularly for midlatitudes. Sulfuric acid aerosols can take up nitric acid near the ice frost point, just before ice nucleation. Aerosols in the tropopause region may show a larger spread of extinction and extinction ratios at different wavelengths than background stratospheric aerosols. The high surface areas and low extinction ratios of subvisible cirrus deduced from satellite observations are unlikely to be due purely to aerosols, except for high sulfate loadings. It is shown that mixtures of liquid aerosols and ice particles can more readily explain these data with only small cloud fractions along the line of sight of the optical sensors. The efficiency of heterogeneous chlorine activation in aerosol/cloud mixtures, the availability of water vapor, sulfate, and nitrate, and the effects of temperature, ammonium, ice nuclei and aircraft emissions on the properties of particles in the tropopause region are explored. (orig.)

  11. Contrail formation in the tropopause region caused by emissions from an Ariane 5 rocket

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    Voigt, Ch.; Schumann, U.; Graf, K.

    2016-07-01

    Rockets directly inject water vapor and aerosol into the atmosphere, which promotes the formation of ice clouds in ice supersaturated layers of the atmosphere. Enhanced mesospheric cloud occurrence has frequently been detected near 80-kilometer altitude a few days after rocket launches. Here, unique evidence for cirrus formation in the tropopause region caused by ice nucleation in the exhaust plume from an Ariane 5-ECA rocket is presented. Meteorological reanalysis data from the European Centre for Medium-Range Weather Forecasts show significant ice supersaturation at the 100-hectopascal level in the American tropical tropopause region on November 26, 2011. Near 17-kilometer altitudes, the temperatures are below the Schmidt-Appleman threshold temperature for rocket condensation trail formation on that day. Immediately after the launch from the Ariane 5-ECA at 18:39 UT (universal time) from Kourou, French Guiana, the formation of a rocket contrail is detected in the high resolution visible channel from the SEVIRI (Spinning Enhanced Visible and InfraRed Imager) on the METEOSAT9 satellite. The rocket contrail is transported to the south and its dispersion is followed in SEVIRI data for almost 2 h. The ice crystals predominantly nucleated on aluminum oxide particles emitted by the Ariane 5-ECA solid booster and further grow by uptake of water vapor emitted from the cryogenic main stage and entrained from the ice supersaturated ambient atmosphere. After rocket launches, the formation of rocket contrails can be a frequent phenomenon under ice supersaturated conditions. However, at present launch rates, the global climate impact from rocket contrail cirrus in the tropopause region is small.

  12. Mesoscale convection system and occurrence of extreme low tropopause temperatures. Observations over Asian summer monsoon region

    Energy Technology Data Exchange (ETDEWEB)

    Jain, A.R.; Mandal, T.K.; Gautam, R. [National Physical Laboratory, New Delhi (India). Radio and Atmospheric Div.; Panwar, V. [National Physical Laboratory, New Delhi (India). Radio and Atmospheric Div.; Delhi Univ. (India). Dept. of Physics and Astrophysics; Rao, V.R. [India Meteorology Dept., New Delhi (India). Satellite Meteorology Div.; Goel, A. [Delhi Univ. (India). Dept. of Physics and Astrophysics; Das, S.S. [Vikram Sarabhai Space Center, Trivandrum (India). Space Physics Lab.; Dhaka, S.K. [Delhi Univ., New Delhi (India). Dept. of Physics and Electronics

    2010-07-01

    The present study examines the process of how tropospheric air enters the stratosphere, particularly in association with tropical mesoscale convective systems (TMCS) which are considered to be one of the causative mechanisms for the observation of extremely low tropopause temperature over the tropics. The association between the phenomena of convection and the observation of extreme low tropopause temperature events is, therefore, examined over the Asian monsoon region using data from multiple platforms. Satellite observations show that the area of low outgoing long wave radiation (OLR), which is a proxy for the enhanced convection, is embedded with high altitude clouds top temperatures ({<=}193 K). A detailed analysis of OLR and 100 hPa temperature shows that both are modulated by westward propagating Rossby waves with a period of {proportional_to}15 days, indicating a close linkage between them. The process by which the tropospheric air enters the stratosphere may, in turn, be determined by how the areas of convection and low tropopause temperature (LTT) i.e. T {<=}191K are spatially located. In this context, the relative spatial distribution of low OLR and LTT areas is examined. Though, the locations of low OLR and LTT are noticed in the same broad area, the two do not always overlap, except for partial overlap in some cases. When there are multiple low OLR areas, the LTT area generally appears in between the low OLR areas. Implications of these observations are also discussed. The present analysis also shows that the horizontal mean winds have a role in the spatial distribution of low OLR and LTT. (orig.)

  13. Dynamical Tropopause Variability and Potential Vorticity Streamers in the Northern Hemisphere——A Climatological Analysis

    Institute of Scientific and Technical Information of China (English)

    Olivia MARTIUS; Cornelia SCHWIERZ; Michael SPRENGER

    2008-01-01

    This study presents a 44-year climatology of potential vorticity (PV) streamers in the Northern Hemi sphere based upon analyses of the ERA-40 reanalysis data set. A comparison to an existing 15-year clima tology yields very good agreement in the locations of PV streamer frequency maxima, but some differences are found in the amplitude of frequencies. The climatology is assessed with the focus on links between PV streamer frequencies and the synoptic- and planetary-scale variability of the dynamical tropopause. A comprehensive overview is provided on where (zonally) and when (seasonally) short-term variability throughout the extra-tropical and sub-tropical tropopause is enhanced or reduced. Several key processes that influence this variability are discussed. Baroclinic processes, for example, determine the variability in the storm-track areas in winter, whereas the Asian summer monsoon significantly influences the variability over Asia. The paper also describes links between the frequency of PV streamers in the extra-tropical and sub tropical tropopause and three major northern hemisphere teleconnection patterns. The observed changes in the PV streamer frequencies are closely related to concomitant variations of PV and its gradient within the tropopause region. During opposite phases of the North Atlantic Oscillation the location of the streamer frequency maxima shifts significantly in the Atlantic and European region in both the extra-tropics and subtropics. The influence of ENSO on the streamer frequencies is most pronounced in the subtropical Pacific.

  14. Separation of the lapse rate and the cold point tropopauses in the tropics and the resulting impact on cloud top-tropopause relationships

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    Munchak, Leigh A.; Pan, Laura L.

    2014-07-01

    Four years of temperature profiles from Constellation Observing System for Meteorology, Ionosphere, and Climate GPS satellite retrievals are used to examine the difference between the World Meteorological Organization lapse rate definition and the cold point definition of the tropopause in the tropics. The separation between the cold point tropopause (CPT) and lapse rate tropopause (LRT) heights is quantified in seasonal averages and with the frequency of occurrence. In seasonal averages, small separations, structures in the December-January-February (DJF) and June-July-August (JJA) seasons. Case studies indicate that breaking Rossby waves and their effects extending into the equatorial region are responsible for the longitudinal structure in the DJF season. The seasonal average CPT-LRT separation therefore identifies the regions of the tropical upper troposphere-lower stratosphere that are controlled by extratropical forcing. Examination of individual profiles shows that a small yet significant fraction (~12%) of temperature profiles has CPT-LRT separations of 1 km or larger in the region of small seasonal average separation. These large separations are produced by wave perturbations of the upper tropospheric temperature structure. The impact of tropopause separation on the cloud top-tropopause relationship is examined using colocated CALIPSO cloud top data. We find that the frequency of clouds above the tropopause is reduced by approximately 50% if the CPT is used instead of LRT. The occurrence of clouds above the CPT is nevertheless significant, especially over the western Pacific in the DJF season and over the Asian monsoon region in the JJA season.

  15. Steady State Ocean Response to Wind Forcing in Extratropical Frontal Regions

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    Cronin, Meghan F.; Tozuka, Tomoki

    2016-01-01

    In regions of strong sea surface temperature (SST) gradients, the surface “geostrophic” currents have a vertical shear aligned with the surface density front defined by the temperature. This surface geostrophic (“thermal wind”) shear can balance a portion of the surface wind stress, altering the classic Ekman response to wind forcing. Here we show that these frontal effects cannot be ignored in the Tropics or in strong frontal regions in the extratropics, such as found in coastal regions and in western boundary currents of all basins. Frontal effects also dominate the classic Ekman response in the regions of both hemispheres where Trade winds change to westerlies. Implications for vertical motion and global heat transport are discussed. PMID:27354231

  16. Steady State Ocean Response to Wind Forcing in Extratropical Frontal Regions.

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    Cronin, Meghan F; Tozuka, Tomoki

    2016-06-29

    In regions of strong sea surface temperature (SST) gradients, the surface "geostrophic" currents have a vertical shear aligned with the surface density front defined by the temperature. This surface geostrophic ("thermal wind") shear can balance a portion of the surface wind stress, altering the classic Ekman response to wind forcing. Here we show that these frontal effects cannot be ignored in the Tropics or in strong frontal regions in the extratropics, such as found in coastal regions and in western boundary currents of all basins. Frontal effects also dominate the classic Ekman response in the regions of both hemispheres where Trade winds change to westerlies. Implications for vertical motion and global heat transport are discussed.

  17. Steady State Ocean Response to Wind Forcing in Extratropical Frontal Regions

    Science.gov (United States)

    Cronin, Meghan F.; Tozuka, Tomoki

    2016-06-01

    In regions of strong sea surface temperature (SST) gradients, the surface “geostrophic” currents have a vertical shear aligned with the surface density front defined by the temperature. This surface geostrophic (“thermal wind”) shear can balance a portion of the surface wind stress, altering the classic Ekman response to wind forcing. Here we show that these frontal effects cannot be ignored in the Tropics or in strong frontal regions in the extratropics, such as found in coastal regions and in western boundary currents of all basins. Frontal effects also dominate the classic Ekman response in the regions of both hemispheres where Trade winds change to westerlies. Implications for vertical motion and global heat transport are discussed.

  18. The heating rate in the tropical tropopause region; Die Erwaermungsrate in der tropischen Tropopausenregion

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    Hamann, Ulrich

    2010-07-01

    The major part of the movement of air masses from the troposphere to the stratosphere takes place in the tropics. The conveyed air mass is transported with the Brewer-Dobson circulation poleward and therefore influences the global stratospheric composition. An important cause variable for the transport of air through the tropical tropopause layer (TTL) is the radiative heating, which is investigated in this work. The influence of trace gases, temperature, and cloudiness on the heating rate is quantified, especially the effect of the overlap of several cloud layers is discussed. The heating rate in the tropics is simulated for one year. Regional differences of the heating rate profile appear between convective and stably stratified regions. By means of trace gas concentrations, temperature, and heating rates it is determined that an enhanced transport of air through the TTL took place between January and April 2007. The comparison with previous works shows that accurate input data sets of trace gases, temperature, and cloudiness and exact methods for the simulation of the radiative transfer are indispensable for modeling of the heating rate with the required accuracy. (orig.)

  19. Lagrangian transport in poleward breaking Rossby waves in the North Atlantic - Europe tropopause region

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    Bartels, J.; Peters, D. [Rostock Univ. (Germany). Inst. fuer Atmosphaerenphysik

    1997-12-31

    The poleward advection of upper-tropospheric air is investigated for poleward Rossby wave breaking events. During boreal winter months the isentropic deformations of the tropopause are examined using maps of Ertel`s potential vorticity (EPV) and contour advection (CA) calculations. The role of ambient baro-tropic flow is further examined by idealized numerical models. In the vicinity of the tropopause the characteristic Lagrangian transport of air masses for ECMWF-analysis data are compared with high resolution (T106) ECHAM4 experiments. (author) 3 refs.

  20. Short-lived brominated hydrocarbons – observations in the source regions and the tropical tropopause layer

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    S. Brinckmann

    2012-02-01

    Full Text Available We conducted measurements of the five important short-lived organic bromine species in the marine boundary layer (MBL. Measurements were made in the Northern Hemisphere mid-latitudes (Sylt Island, North Sea in June 2009 and in the tropical Western Pacific during the TransBrom ship campaign in October 2009. For the one-week time series on Sylt Island, mean mixing ratios of CHBr3, CH2Br2, CHBr2Cl and CH2BrCl were 2.0, 1.1, 0.2, 0.1 ppt, respectively. We found maxima of 5.8 and 1.6 ppt for the two main components CHBr3 and CH2Br2. Along the cruise track in the Western Pacific (between 41° N and 13° S we measured mean mixing ratios of 0.9, 0.9, 0.2, 0.1 and 0.1 ppt for CHBr3, CH2Br2, CHBrCl2, CHBr2Cl and CH2BrCl. Air samples with coastal influence showed considerably higher mixing ratios than the samples with open ocean origin. Correlation analyses of the two data sets yielded strong linear relationships between the mixing ratios of four of the five species (except for CH2BrCl. Using a combined data set from the two campaigns and a comparison with the results from two former studies, rough estimates of the molar emission ratios between the correlated substances were: 9/1/0.35/0.35 for CHBr3/CH2Br2/CHBrCl2/CHBr2Cl. Additional measurements were made in the tropical tropopause layer (TTL above Teresina (Brazil, 5° S in June 2008, using balloon-borne cryogenic whole air sampling technique. Near the level of zero clear-sky net radiative heating (LZRH at 14.8 km about 2.25 ppt organic bromine was bound to the five short-lived species, making up 13% of total organic bromine (17.82 ppt. CH2Br2 (1.45 ppt and CHBr3 (0.56 ppt accounted for 90% of the budget of short-lived compounds in that region. Near the

  1. The tropical tropopause inversion layer: variability and modulation by equatorial waves

    Science.gov (United States)

    Pilch Kedzierski, Robin; Matthes, Katja; Bumke, Karl

    2016-09-01

    The tropical tropopause layer (TTL) acts as a transition layer between the troposphere and the stratosphere over several kilometers, where air has both tropospheric and stratospheric properties. Within this region, a fine-scale feature is located: the tropopause inversion layer (TIL), which consists of a sharp temperature inversion at the tropopause and the corresponding high static stability values right above, which theoretically affect the dispersion relations of atmospheric waves like Rossby or inertia-gravity waves and hamper stratosphere-troposphere exchange (STE). Therefore, the TIL receives increasing attention from the scientific community, mainly in the extratropics so far. Our goal is to give a detailed picture of the properties, variability and forcings of the tropical TIL, with special emphasis on small-scale equatorial waves and the quasi-biennial oscillation (QBO).We use high-resolution temperature profiles from the COSMIC satellite mission, i.e., ˜ 2000 measurements per day globally, between 2007 and 2013, to derive TIL properties and to study the fine-scale structures of static stability in the tropics. The situation at near tropopause level is described by the 100 hPa horizontal wind divergence fields, and the vertical structure of the QBO is provided by the equatorial winds at all levels, both from the ERA-Interim reanalysis.We describe a new feature of the equatorial static stability profile: a secondary stability maximum below the zero wind line within the easterly QBO wind regime at about 20-25 km altitude, which is forced by the descending westerly QBO phase and gives a double-TIL-like structure. In the lowermost stratosphere, the TIL is stronger with westerly winds. We provide the first evidence of a relationship between the tropical TIL strength and near-tropopause divergence, with stronger (weaker) TIL with near-tropopause divergent (convergent) flow, a relationship analogous to that of TIL strength with relative vorticity in the

  2. Stratosphere-troposphere exchange in an extratropical cyclone, calculated with a Lagrangian method

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    M. Sigmond

    Full Text Available A Lagrangian technique is developed and applied to calculate stratosphere-troposphere exchange in an extratropical cyclone. This exchange is computed from the potential vorticity or PV along trajectories, calculated from ECMWF circulation data. Special emphasis is put on the statistical significance of the results. The computed field of the cross-tropopause flux is dominated by elongated patterns of statistically significant large downward and small upward fluxes. The downward fluxes mainly occur in the lower part of the considered tropopause folds. The upward fluxes are found near the entrance of the folds, in the tropopause ridges. The ratio between the area averaged downward and upward cross-tropopause fluxes increases with increasing strength of the cyclone. Since the largest fluxes are shown to occur in the regions with the largest wind shear, where PV-mixing is thought to cause large cross-tropopause fluxes, the results are expected to be reliable, at least in a qualitative sense. The position of a tropopause fold along the northwest coast of Africa is confirmed by total ozone observations. The results indicate that the applied Lagrangian technique is an appropriate tool for diagnosing stratosphere-troposphere exchange.

    Key words: Meteorology and atmospheric dynamics (general circulation; mesoscale meteorology; middle atmosphere dynamics

  3. The stable isotopic composition of molecular hydrogen in the tropopause region probed by the CARIBIC aircraft

    Science.gov (United States)

    Batenburg, A. M.; Schuck, T. J.; Baker, A. K.; Zahn, A.; Brenninkmeijer, C. A. M.; Röckmann, T.

    2012-05-01

    More than 450 air samples that were collected in the upper troposphere - lower stratosphere (UTLS) region by the CARIBIC aircraft (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) have been analyzed for molecular hydrogen (H2) mixing ratios (χ(H2)) and H2 isotopic composition (deuterium content, δD). More than 120 of the analyzed samples contained air from the lowermost stratosphere (LMS). These show that χ(H2) does not vary appreciably with O3-derived height above the thermal tropopause (TP), whereas δD does increase with height. The isotope enrichment is caused by H2 production and destruction processes that enrich the stratospheric H2 reservoir in deuterium (D); the exact shapes of the profiles are mainly determined by mixing of stratospheric with tropospheric air. Tight negative correlations are found between δD and the mixing ratios of methane (χ(CH4)) and nitrous oxide (χ(N2O)), as a result of the relatively long lifetimes of these three species. The correlations are described by δD[‰]=-0.35 · χ(CH4)[ppb]+768 and δD[‰]=-1.90· χ(N2O)[ppb]+745. These correlations are similar to previously published results and likely hold globally for the LMS. Samples that were collected from the Indian subcontinent up to 40° N before, during and after the summer monsoon season show no significant seasonal change in χ(H2), but δD is up to 12.3‰ lower in the July, August and September monsoon samples. This δD decrease is correlated with the χ(CH4) increase in these samples. The significant correlation with χ(CH4) and the absence of a perceptible χ(H2) increase that accompanies the δD decrease indicates that microbial production of very D-depleted H2 in the wet season may contribute to this phenomenon. Some of the samples have very high χ(H2) and very low δD values, which indicates a pollution effect. Aircraft engine exhaust plumes are a suspected cause, since the effect mostly occurs in samples

  4. The stable isotopic composition of molecular hydrogen in the tropopause region probed by the CARIBIC aircraft

    Directory of Open Access Journals (Sweden)

    A. M. Batenburg

    2012-05-01

    Full Text Available More than 450 air samples that were collected in the upper troposphere – lower stratosphere (UTLS region by the CARIBIC aircraft (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container have been analyzed for molecular hydrogen (H2 mixing ratios (χ(H2 and H2 isotopic composition (deuterium content, δD.

    More than 120 of the analyzed samples contained air from the lowermost stratosphere (LMS. These show that χ(H2 does not vary appreciably with O3-derived height above the thermal tropopause (TP, whereas δD does increase with height. The isotope enrichment is caused by H2 production and destruction processes that enrich the stratospheric H2 reservoir in deuterium (D; the exact shapes of the profiles are mainly determined by mixing of stratospheric with tropospheric air. Tight negative correlations are found between δD and the mixing ratios of methane (χ(CH4 and nitrous oxide (χ(N2O, as a result of the relatively long lifetimes of these three species. The correlations are described by δD[‰]=−0.35 · χ(CH4[ppb]+768 and δD[‰]=−1.90· χ(N2O[ppb]+745. These correlations are similar to previously published results and likely hold globally for the LMS.

    Samples that were collected from the Indian subcontinent up to 40° N before, during and after the summer monsoon season show no significant seasonal change in χ(H2, but δD is up to 12.3‰ lower in the July, August and September monsoon samples. This δD decrease is correlated with the χ(CH4 increase in these samples. The significant correlation with χ(CH4 and the absence of a perceptible χ(H2 increase that accompanies the δD decrease indicates that microbial production of

  5. Letter to the Editor Seasonal variations and vertical movement of the tropopause in the UTLS region

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    D. E. Shallcross

    Full Text Available Based on the tracking of the movement of the tropopause over the whole year, the extent/depth of stratosphere-troposphere exchange (STE events and their seasonal variations is investigated. It is found that a stratospheric signature can be observed at pressures as high as 400 hPa in a hemisphere during its winter to spring period, while a tropospheric signature can be observed at pressures as low as 190 hPa during the hemispheric summer to autumn months. The major implication for such a pronounced vertical movement is that the downward penetration of air from the stratosphere is likely to deposit elevated levels of O3 into the upper troposphere. Though the analysis at 250 hPa reveals that the values of the stratosphere-troposphere index are similar all year round, a result which is consistent with other studies, it is found that an intrusion from the stratosphere to the troposphere is more likely to occur during the hemispheric winter to spring period than other seasons.Key words. Atmospheric composition and structure (pressure, density, and temperature; troposphere–composition and chemistry

  6. Characteristics of the global thermal tropopause derived from multiple radio occultation measurements

    Science.gov (United States)

    Li, Wei; Yuan, Yun-bin; Chai, Yan-Ju; Liou, Yuei-An; Ou, Ji-kun; Zhong, Shi-ming

    2017-03-01

    tropical and extratropical regions. In both the tropics and Arctic, close correlation of the interannual variations is revealed between tropopause parameters and stratospheric temperatures in localized regions as well as zonal mean results while no such relationship is observed in the middle latitudes; and Diurnal variation of the equatorial tropopause shows warmer temperature in the morning and cooler value at midnight.

  7. Transport timescales and tracer properties in the extratropical UTLS

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    P. Hoor

    2010-05-01

    Full Text Available A comprehensive evaluation of seasonal backward trajectories initialized in the Northern Hemisphere lowermost stratosphere (LMS has been performed to investigate the origin of air parcels and the main mechanisms determining characteristic structures in H2O and CO within the LMS. In particular we explain the fundamental role of the transit time since last tropopause crossing (tTST for the chemical structure of the LMS as well as the feature of the extra-tropical tropopause transition layer (ExTL as identified from CO profiles. The distribution of H2O in the background LMS above Θ=320 K and 340 K in northern winter and summer, respectively, is found to be governed mainly by the saturation mixing ratio, which in turn is determined by the Lagrangian Cold Point (LCP encountered by each trajectory. Most of the backward trajectories from this region in the LMS experienced their LCP in the tropics and sub-tropics. The transit time since crossing the tropopause from the troposphere to the stratosphere (tTST is independent of the H2O value of the air parcel. TST often occurs 20 days after trajectories have encountered their LCP. CO, on the other hand, depends strongly on tTST due to its finite lifetime. The ExTL as identified from CO measurements is then explained as a layer of air just above the tropopause, which on average encountered TST fairly recently.

  8. Seasonal and inter-annual variations in Troposphere-to-Stratosphere Transport from the Tropical Tropopause Layer

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    J. G. Levine

    2008-01-01

    Full Text Available In an earlier study of troposphere-to-stratosphere transport (TST via the tropical tropopause layer (TTL, we found that the vast majority of air parcels undergoing TST from the base of the TTL enter the extratropical lowermost stratosphere quasi-horizontally and show little or no regional preference with regards to origin in the TTL or entry into the stratosphere. We have since repeated the trajectory calculations - originally limited to a single northern hemisphere winter period - in a variety of months and years to assess how robust our earlier findings are to change of timing. To first order, we find that the main conclusions hold, irrespective of the season, year and phase of the El Niño Southern Oscillation (ENSO. We also explore: the distribution of TST between the northern and southern hemispheres; the sensitivity of modelled TST to the definition of the tropopause; and the routes by which air parcels undergo transport exclusively to the stratospheric overworld. Subject to a dynamical definition of the tropopause, we identify a strong bias towards TST in the southern hemisphere, particularly during the northern hemisphere summer. The main difference on switching to the World Meteorological Organization's thermal tropopause definition is that much less TST is modelled in the subtropics and, relative to the dynamical definition, we calculate significantly less transport into the extratropical lowermost stratosphere (ELS – an important region with regards to ozone chemistry. In contrast to the rather homogeneous nature of TST into the ELS, we find that transport to the overworld takes place from relatively well-defined regions of the TTL, predominantly above the West Pacific and Indonesia, except for an El Niño period in which most transport takes place from regions above the East Pacific and South America.

  9. On the structure of the extra-tropical transition layer from in-situ observations

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    I. Pisso

    2012-10-01

    Full Text Available In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994–2007 were combined to investigate the Extra-tropical Transition Layer (ExTL region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces allowed us to relate the dynamical definition of the tropopause with trace gases distributions and vertical gradients and hence analyse its latitudinal dependence and seasonal variability. Analysis of the available data provides a working definition of the upper limit of the ExTL based on the upper limit of the region of high vertical CO gradient in PV relative coordinates. A secondary local maximum in vertical O3 gradient can be used a proxy for the lower limit, although it is less clearly defined than that of CO. The sloping isopleths of CO and O3 mixing ratios and the CO mixing ratio gradient are consistent with isopleths in purely dynamical diagnostics such as χ30 d, the proportion of air masses in contact with the PBL within one month and underline the differences between the PV based and chemical tropopauses. The use of tropopause relative coordinates allows different seasons to be analysed together to produce climatological means. The weak dependence of dynamical diagnostics of transport on the absolute values of tracer concentrations makes them a suitable process-oriented tool to evaluate global chemical models and make Lagrangian comparisons.

  10. On the structure of the extra-tropical transition layer from in-situ observations

    Science.gov (United States)

    Pisso, I.; Law, K. S.; Fierli, F.; Haynes, P. H.; Hoor, P.; Palazzi, E.; Ravegnani, F.; Viciani, S.

    2012-10-01

    In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994-2007 were combined to investigate the Extra-tropical Transition Layer (ExTL) region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces allowed us to relate the dynamical definition of the tropopause with trace gases distributions and vertical gradients and hence analyse its latitudinal dependence and seasonal variability. Analysis of the available data provides a working definition of the upper limit of the ExTL based on the upper limit of the region of high vertical CO gradient in PV relative coordinates. A secondary local maximum in vertical O3 gradient can be used a proxy for the lower limit, although it is less clearly defined than that of CO. The sloping isopleths of CO and O3 mixing ratios and the CO mixing ratio gradient are consistent with isopleths in purely dynamical diagnostics such as χ30 d, the proportion of air masses in contact with the PBL within one month and underline the differences between the PV based and chemical tropopauses. The use of tropopause relative coordinates allows different seasons to be analysed together to produce climatological means. The weak dependence of dynamical diagnostics of transport on the absolute values of tracer concentrations makes them a suitable process-oriented tool to evaluate global chemical models and make Lagrangian comparisons.

  11. Sensitivity of Cross-Tropopause Convective Transport to Tropopause Definition

    Science.gov (United States)

    Maddox, E.; Mullendore, G. L.

    2016-12-01

    An idealized three-dimensional cloud-resolving model is used to simulate cross-tropopause boundary layer mass transport in a midlatitude supercell. A ten-hour simulation is conducted to encompass the growth and decay cycle, with focus on irreversible transport above the tropopause. However, several tropopause definitions are present in the literature, and the impact of tropopause definition on irreversible cross-tropopause transport has not been quantified. Six previously published tropopause definitions are evaluated to determine the sensitivity of tropopause definition on midlatitude irreversible cross-tropopause transport. These definitions include specific values of altitude, temperature lapse rate (i.e., WMO definition), potential vorticity, stratospheric tracer concentration, static stability, and curvature of static stability. This investigation highlights the challenge of defining a tropopause during active deep convection and shows that some definitions (e.g., potential vorticity) may not be appropriate for cross-tropopause transport studies that resolve deep convection.

  12. Observations of the UTLS: An analysis of the double tropopause and its relationship to Rossby waves and the tropopause inversion layer

    Science.gov (United States)

    Peevey, Tanya

    The upper troposphere lower stratosphere (UTLS) is a region of minimum temperatures that contains the tropopause. As a transition region between the troposphere and the stratosphere, the UTLS contains various processes that facilitate stratosphere-troposphere exchange (STE) which can redistribute radiatively important species such as water vapor or ozone. One potential marker for STE is the double tropopause (DT). Therefore this study seeks to further understand how DTs form and how they could enhance the current understanding of some STE processes in the UTLS. Using data from the High Resolution Dynamic Limb Sounder (HIRDLS), a data set with high vertical and horizontal resolution, newly discovered DT structures are found over the Pacific and Atlantic oceans that suggest a relationship between the DT and both storm tracks and Rossby waves. The association between DTs and storm tracks is examined by further analyzing the recently discovered and unexpected relationship between the DT and the tropopause inversion layer (TIL) in a developing baroclinic disturbance. Results show an increase in the number of DTs when the lapse rate of the extratropical TIL is less than -2°C/km, i.e. when the TIL is stronger and the local stability is higher. Composites of ERA-Interim DT profiles for three different TIL strengths shows that the vertical motion and relative vorticity both decrease as the TIL increases, which suggests the warm conveyor belt as a mechanism. This is investigated further with a case study analysis of a developing extratropical cyclone in the Pacific Ocean. Additionally, an analysis of DTs in relation to the large scale flow responsible for storm development shows a strong correlation between monthly Rossby wave activity, ozone laminae and DT variability. Further examination shows that if these waves break a DT will be found with a wave breaking event about 30% of the time in the eastern Pacific and eastern Atlantic oceans, both regions of poleward wave

  13. Tropopause fold occurrence rates over the Antarctic station Troll (72° S, 2.5° E

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    M. Mihalikova

    2013-04-01

    Full Text Available One of the important mechanisms of stratosphere–troposphere exchange, which brings ozone-rich stratospheric air to low altitudes in extratropical regions, is transport related to tropopause folds. The climatology of folds has been studied at high latitudes of the Northern Hemisphere with the help of radars and global models. Global models supply information about fold occurrence rates at high latitudes of the Southern Hemisphere as well, but so far comparisons with direct measurements are rare. The Moveable Atmospheric Radar for Antarctica (MARA, a 54.5 MHz wind-profiler radar, has been operated at the Norwegian year-round station Troll, Antarctica (72° S, 2.5° E since December 2011. Frequent tropopause fold signatures have been observed. In this study, based on MARA observations, an occurrence rate statistics of tropopause folds from December 2011 until November 2012 has been made, and radar data have been compared with the analysis from the European Center for Medium-Range Weather Forecasting (ECMWF. The fold occurrence rates exhibit an annual cycle with winter maximum and summer minimum and suggest significantly higher occurrence rates for the given location than those obtained previously by global model studies.

  14. Tropopause fold occurrence rates over the Antarctic station Troll (72° S, 2.5° E)

    Science.gov (United States)

    Mihalikova, M.; Kirkwood, S.

    2013-04-01

    One of the important mechanisms of stratosphere-troposphere exchange, which brings ozone-rich stratospheric air to low altitudes in extratropical regions, is transport related to tropopause folds. The climatology of folds has been studied at high latitudes of the Northern Hemisphere with the help of radars and global models. Global models supply information about fold occurrence rates at high latitudes of the Southern Hemisphere as well, but so far comparisons with direct measurements are rare. The Moveable Atmospheric Radar for Antarctica (MARA), a 54.5 MHz wind-profiler radar, has been operated at the Norwegian year-round station Troll, Antarctica (72° S, 2.5° E) since December 2011. Frequent tropopause fold signatures have been observed. In this study, based on MARA observations, an occurrence rate statistics of tropopause folds from December 2011 until November 2012 has been made, and radar data have been compared with the analysis from the European Center for Medium-Range Weather Forecasting (ECMWF). The fold occurrence rates exhibit an annual cycle with winter maximum and summer minimum and suggest significantly higher occurrence rates for the given location than those obtained previously by global model studies.

  15. Effects of air-sea interaction on extended-range prediction of geopotential height at 500 hPa over the northern extratropical region

    Science.gov (United States)

    Wang, Xujia; Zheng, Zhihai; Feng, Guolin

    2017-02-01

    The contribution of air-sea interaction on the extended-range prediction of geopotential height at 500 hPa in the northern extratropical region has been analyzed with a coupled model form Beijing Climate Center and its atmospheric components. Under the assumption of the perfect model, the extended-range prediction skill was evaluated by anomaly correlation coefficient (ACC), root mean square error (RMSE), and signal-to-noise ratio (SNR). The coupled model has a better prediction skill than its atmospheric model, especially, the air-sea interaction in July made a greater contribution for the improvement of prediction skill than other months. The prediction skill of the extratropical region in the coupled model reaches 16-18 days in all months, while the atmospheric model reaches 10-11 days in January, April, and July and only 7-8 days in October, indicating that the air-sea interaction can extend the prediction skill of the atmospheric model by about 1 week. The errors of both the coupled model and the atmospheric model reach saturation in about 20 days, suggesting that the predictable range is less than 3 weeks.

  16. Measurement of western U.S. baseline ozone from the surface to the tropopause and assessment of downwind impact regions

    Science.gov (United States)

    Cooper, O. R.; Oltmans, S. J.; Johnson, B. J.; Brioude, J.; Angevine, W.; Trainer, M.; Parrish, D. D.; Ryerson, T. R.; Pollack, I.; Cullis, P. D.; Ives, M. A.; Tarasick, D. W.; Al-Saadi, J.; Stajner, I.

    2011-11-01

    Since 1997, baseline ozone monitoring from the surface to the tropopause along the U.S. west coast has been limited to the weekly ozonesondes from Trinidad Head, California. To explore baseline ozone at other latitudes, an ozonesonde network was implemented during spring 2010, including four launch sites along the California coast. Modeling indicated that North American pollution plumes impacted the California coast primarily below 3 km, but had no measurable impact on the average coastal ozone profiles. Vertical and latitudinal variation in free tropospheric baseline ozone appears to be partly explained by polluted and stratospheric air masses that descend isentropically along the west coast. Above 3 km, the dominant sources of ozone precursors were China and international shipping, while international shipping was the greatest source below 2 km. Approximately 8-10% of the baseline ozone that enters California in the 0-6 km range impacts the surface of the USA, but very little reaches the eastern USA. Within California, the major impact of baseline ozone above 2 km is on the high elevation terrain of eastern California. Baseline ozone below 2 km has its strongest impact on the low elevation sites throughout the state. To quantify ozone production within California we compared inland ozone measurements to baseline measurements. For average daytime conditions, we found no enhancements of lower tropospheric ozone in the northern Central Valley, but enhancements of 12-23% were found in the southern Central Valley. Enhancements above Joshua Tree were greater, 33-41%, while the greatest enhancements occurred over the LA Basin, 32-63%.

  17. Relationships among Brewer-Dobson circulation, double tropopauses, ozone and lower-stratospheric water vapor

    Science.gov (United States)

    Castanheira, J. M.; Peevey, T. R.; Marques, C. A. F.; Olsen, M. A.

    2012-04-01

    This communication will discuss the statistical relationships between the variability of the area covered by double tropopause events and the variabilities of total column ozone and of lower-stratospheric water vapor. The QBO signal in double tropopause events statistics and the relationship between tropical upwelling and the near global (50oS - 50oN) lower stratospheric water vapour will be also presented. The analysis is based on both reanalysis data (ERA-Interim) and satellite data. Significant correlations were found between the area covered by double tropopause events in the latitudinal band 20 - 65oN and the gradient of total column ozone in the subtropical Northern Hemisphere. Significant correlations were also found between de global area of double tropopause events and the near global (50oS - 50oN) water vapour in the lower stratosphere. The relationship between double tropopause events and lower stratospheric ozone is detailed by a correlation analysis between the frequencies of ozone laminae and double tropopause events as found in the HIRDLS data. The correlations of DT variables with total column ozone and ozone laminae are both consistent with intrusion events of tropospheric tropical air into the lower extratropical stratosphere, with the tropical tropopause overlaying the extratropical one. The poleward excursions of the tropical tropopause are also consistent with the found negative correlation between the area extension of DTs and the near global lower stratospheric water vapour. Finally, we will show the existence of a significant negative correlation between the tropical upwelling, determined using the "downward control principle", and the near global lower stratospheric water vapor.

  18. Fate of long-lived trace species near the Northern Hemispheric tropopause : Carbon dioxide, methane, ozone, and sulfur hexafluoride

    NARCIS (Netherlands)

    Zahn, A.; Neubert, R.; Maiss, M.; Platt, U.

    1999-01-01

    The mixing ratios of CO2, CH4, O-3, and SF6 were measured in 118 whole air samples collected onboard a Transall C-160 aircraft around the NH extratropical tropopause in the winters 1993-1994 and 1994-1995. The samples originate mainly from the upper troposphere (similar to 7 km) and partly from the

  19. Tropical tropopause layer cirrus and its relation to tropopause

    Science.gov (United States)

    Tseng, H.-H.; Fu, Q.

    2017-02-01

    This study examines the spatial and temporal patterns of tropical tropopause layer (TTL) cirrus clouds (i.e., clouds with bases higher than 14.5 km) and their relationship to tropical tropopause including both cold point tropopause (CPT) and lapse rate tropopause (LRT). We use eight years (2006-2014) data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) measurements. In addition to the CALIPSO cloud layer product, the clouds included in the current CALIPSO dataset as stratospheric features have been considered by separating clouds from aerosols, which are important in the TTL cloud analysis. It is also shown that the temporal variation of the stratospheric aerosols matches well with the volcanic eruption events. The TTL cloud fraction and the tropical tropopause temperature both have pronounced annual cycles and are strongly negatively correlated both temporally and spatially. The examination of the TTL cloud height relative to tropopause from collocated CALIPSO and COSMIC observations indicates that the tropopause plays a critical role in constraining the TTL cloud top height. We show that the probability density function of TTL cloud top height peaks just below the CPT while the occurrence of TTL clouds with cloud tops above the CPT could be largely explained by observed tropopause height uncertainty associated with the COSMIC vertical resolution.

  20. Climatological perspectives of air transport from atmospheric boundary layer to tropopause layer over Asian monsoon regions during boreal summer inferred from Lagrangian approach

    Directory of Open Access Journals (Sweden)

    B. Chen

    2012-02-01

    Full Text Available The Asian Summer Monsoon (ASM region has been recognized as a key region that plays a vital role in troposphere-to-stratosphere transport (TST, which can significantly impact the budget of global atmospheric constituents and climate change. However, the details of transport from the boundary layer (BL to tropopause layer (TL over this region, particularly from a climatological perspective, remains an issue of uncertainty. In this study, we present the climatological properties of BL-to-TL transport over the ASM region during boreal summer season (June-July-August from 2001 to 2009. A comprehensive tracking analysis is conducted based on a large ensemble of TST-trajectories departing from the atmospheric BL and arriving at TL. Driven by the winds fields from the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research Global Forecast System, all TST-trajectories are selected from the high resolution datasets generated by the Lagrangian particle transport model FLEXPART using a domain-filling technique. Three key atmospheric boundary layer sources for BL-to-TL transport are identified with their contributions: (i 38% from the region between tropical Western Pacific region and South China Seas (WP, (ii 21% from Bay of Bengal and South Asian subcontinent (BOB, and (iii 12% from the Tibetan Plateau, which includes the South Slope of the Himalayas (TIB. Controlled by the different patterns of atmospheric circulation, the air masses originating from these three source regions are transported along the different tracks into the TL. The spatial distributions of these three source regions remain similarly from year to year. The timescales of transport from BL to TL by the large-scale ascents range from 1 to 7 weeks, contributing up to 60–70% of the overall TST; whereas the transport governed by the deep convection overshooting becomes faster, with timescales of 1–2 days and contributions of 20–30%. These

  1. Climatological perspectives of air transport from atmospheric boundary layer to tropopause layer over Asian monsoon regions during boreal summer inferred from Lagrangian approach

    Directory of Open Access Journals (Sweden)

    B. Chen

    2012-07-01

    Full Text Available The Asian Summer Monsoon (ASM region has been recognized as a key region that plays a vital role in troposphere-to-stratosphere transport (TST, which can significant impact the budget of global atmospheric constituents and climate change. However, the details of transport from the boundary layer (BL to tropopause layer (TL over these regions, particularly from a climatological perspective, remain an issue of uncertainty. In this study, we present the climatological properties of BL-to-TL transport over the ASM region during boreal summer season (June-July-August from 2001 to 2009. A comprehensive tracking analysis is conducted based on a large ensemble of TST-trajectories departing from the atmospheric BL and arriving at TL. Driven by the winds fields from NCEP/NCAR Global Forecast System, all the TST-trajectories are selected from the high resolution datasets generated by the Lagrangian particle transport model FLEXPART using a domain-filling technique. Three key atmospheric boundary layer sources for BL-to-TL transport are identified with their contributions: (i 38% from the region between tropical Western Pacific region and South China Seas (WP (ii 21% from Bay of Bengal and South Asian subcontinent (BOB, and (iii 12% from the Tibetan Plateau, which includes the South Slope of the Himalayas (TIB. Controlled by the different patterns of atmospheric circulation, the air masses originated from these three source regions are transported along the different tracks into the TL. The spatial distributions of three source regions keep similarly from year to year. The timescales of transport from BL to TL by the large-scale ascents r-range from 1 to 7 weeks contributing up to 60–70% of the overall TST, whereas the transport governed by the deep convection overshooting become faster on a timescales of 1–2 days with the contributions of 20–30%. These results provide clear policy implications for the control of very short lived substances

  2. Comparison and statistics of aerosol properties measured in situ in the tropopause region during the aircraft campaigns of POLSTAR, LACE 98, UFA, EXPORT, INCA and SCAVEX

    Science.gov (United States)

    Minikin, A.; Petzold, A.; Fiebig, M.; Hendricks, J.; Schröder, F.; Schlager, H.

    2003-04-01

    In the past few years the DLR Falcon 20, a German twin-jet research aircraft with a maximum ceiling of 13~km, has participated in a number of experiments devoted to the characterization of aerosol properties in the troposphere and the tropopause region. Total aerosol number concentrations for Aitken mode and ultrafine particles have been measured with condensation particle counters with different lower cut-off diameters in the range from 3 to 15~nm. For a subset of data, the fractionation between volatile, semi-volatile and refractory particles was determined. Total concentration of accumulation mode particles as well as aerosol size distributions were determined from measurements of a combination of optical aerosol spectrometer probes (PMS PCASP-100X and FSSP-300). In this contribution we report on mean tropospheric vertical profiles of aerosol properties and the statistics of aerosol abundance and size distributions in the upper troposphere for different campaigns mainly conducted in Europe but with differing continental character. Results of the projects LACE~98, UFA, EXPORT and SCAVEX refer to measurements over Germany and neighboring countries in spring, summer and autumn. Contrasting geographical regions are addressed by the results of the POLSTAR and INCA campaigns (high latitudes of the northern hemisphere and mid-latitudes of the southern and northern hemisphere, respectively, the latter with only small continental influence). We compare the results of the different campaigns in order to assess the representativity and natural variability of aerosol properties measured in situ in the upper troposphere and in the transition to the lower stratosphere. Experimental results are compared to simulations of the ECHAM global climate model. Simulated aerosol mass concentrations are in good agreement with observations of the mean vertical distribution of accumulation mode particles and the contrasting concentration level in the northern and southern hemisphere mid-latitudes.

  3. An Analysis of the Energetics of Tropical and Extra-Tropical Regions for Warm ENSO Composite Episodes

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    Zayra Christine Sátyro

    Full Text Available Abstract This study focuses on the quantification and evaluation of the effects of ENSO (El Niño Southern Oscillation warm phases, using a composite of five intense El Niño episodes between 1979 – 2011 on the Energetic Lorenz Cycle for four distinct regions around the globe: 80° S – 5° N (region 1, 50° S – 5° N (region 2, 30° S – 5° N (region 3, and 30° S – 30° N (region 4, using Data from NCEP reanalysis-II. Briefly, the results showed that zonal terms of potential energy and kinetic energy were intensified, except for region 1, where zonal kinetic energy weakened. Through the analysis of the period in which higher energy production is observed, a strong communication between the available zonal potential and the zonal kinetic energy reservoirs can be identified. This communication weakened the modes linked to eddies of potential energy and kinetic energy, as well as in the other two baroclinic conversions terms. Furthermore, the results indicate that for all the regions, the system itself works to regain its stable condition.

  4. Interannual variability over the eastern North Atlantic Ocean: Chemical and meteorological evidence for tropical influence on regional-scale transport in the extratropics

    Science.gov (United States)

    Doddridge, Bruce G.; Dirmeyer, Paul A.; Merrill, John T.; Oltmans, Samuel J.; Dickerson, Russell R.

    1994-11-01

    Observed boreal fall season (September-November) 1991 surface CO data from Mace Head, Ireland, are characterized by particularly high mixing ratios, as evidenced by high means, medians, and maxima for those months, relative to the same dato for boreal fall 1992. Air parcels characterized by elevated CO during fall 1991 are attributed to European sources on the basis of isentropic back trajectory analysis. A histogram of the 1991 data shows a bimodal distribution representing two discrete source regions, North Atlantic and European, while the 1992 data show only one mode, representing primarily zonal westerly flow over the North Atlantic Ocean. A similar distinction exists in O3 data between the two years. Considerable interannual variability has important implications for observationalists and modelers alike; an inherent uncertainty is introduced by basing any determination of trend from only a few years of data. An isentropic flow climatology for Mace Head illustrates significant differences in the regional-scale flow patterns to Mace Head between the 1991 and the 1992 fall seasons. These differences have been examined in terms of general dynamical principles and tropical/extratropical coupling. There is evidence of the existence of Rossby wave links with the tropical upper troposphere over South America and the central Pacific Ocean which are responsible for the climatic forcing giving rise to the observed interannual variation in large-scale flow patterns and influencing the chemical character of air parcels reaching Mace Head. Using CO as a tracer for short-lived continental anthropogenic O3 precursors and calculating ΔO3/ΔCO for air parcel trajectories following anticyclonic paths over western Europe during the late summer and fall season of 1991, we estimate O3 production over western Europe at about 66 (40-96) billion moles of O3 per summer (˜3 Tg O3 per summer), based on 1985 CO emission inventory dam (37 Tg CO yr-1 for western Europe).

  5. Models are likely to underestimate increase in heavy rainfall in the extratropical regions with high rainfall intensity

    Science.gov (United States)

    Borodina, Aleksandra; Fischer, Erich M.; Knutti, Reto

    2017-07-01

    Model projections of regional changes in heavy rainfall are uncertain. On timescales of few decades, internal variability plays an important role and therefore poses a challenge to detect robust model response in heavy rainfall to rising temperatures. We use spatial aggregation to reduce the major role of internal variability and evaluate the heavy rainfall response to warming temperatures with observations. We show that in the regions with high rainfall intensity and for which gridded observations exist, most of the models underestimate the historical scaling of heavy rainfall and the land fraction with significant positive heavy rainfall scalings during the historical period. The historical behavior is correlated with the projected heavy rainfall intensification across models allowing to apply an observational constraint, i.e., to calibrate multimodel ensembles with observations in order to narrow the range of projections. The constraint suggests a substantially stronger intensification of future heavy rainfall than the multimodel mean.

  6. Tracer measurements in the tropical tropopause layer during the AMMA/SCOUT-O3 aircraft campaign

    Directory of Open Access Journals (Sweden)

    A. Ulanovski

    2009-11-01

    K on 7 August. However, the absence of expected corresponding signatures in other tracer data makes this evidence inconclusive, and overall there is little indication from the observations that overshooting convection has a profound impact on TTL composition during AMMA. We find the amount of photochemically aged air isentropically mixed into the TTL across the subtropical tropopause to be not significant. Using the N2O observations we estimate the fraction of aged extratropical stratospheric air in the TTL to be 0.0±0.1 up to 370 K during the local flights, increasing above this level to 0.2±0.15 at 390 K. The subtropical barrier, as indicated by the slope of the correlation between N2O and O3 between 415 and 490 K, does not appear as a sharp border between the tropics and extratropics, but rather as a gradual transition region between 10 and 25° N latitude where isentropic mixing between these two regions may occur.

  7. Tracer measurements in the tropical tropopause layer during the AMMA/SCOUT-O3 aircraft campaign

    Directory of Open Access Journals (Sweden)

    C. D. Homan

    2010-04-01

    small signatures indicative of this process were found in CO2 profiles between 390 and 410 K during the flights of 4 and 8 August, and in CO data at 410 K on 7 August. However, the absence of expected corresponding signatures in other tracer data makes this evidence inconclusive, and overall there is little indication from the observations that overshooting convection has a profound impact on gas-phase tracer TTL composition during AMMA.

    We find the amount of photochemically aged air isentropically mixed into the TTL across the subtropical tropopause to be not significant. Using the N2O observations we estimate the fraction of aged extratropical stratospheric air in the TTL to be 0.0±0.1 up to 370 K during the local flights. Above the TTL this fraction increases to 0.3±0.1 at 390 K.

    The subtropical barrier, as indicated by the slope of the correlation between N2O and O3 between 415 and 490 K, does not appear as a sharp border between the tropics and extratropics, but rather as a gradual transition region between 10° N and 25° N where isentropic mixing between these two regions may occur.

  8. Tracer measurements in the tropical tropopause layer during the AMMA/SCOUT-O3 aircraft campaign

    Science.gov (United States)

    Homan, C. D.; Volk, C. M.; Kuhn, A. C.; Werner, A.; Baehr, J.; Viciani, S.; Ulanovski, A.; Ravegnani, F.

    2010-04-01

    August. However, the absence of expected corresponding signatures in other tracer data makes this evidence inconclusive, and overall there is little indication from the observations that overshooting convection has a profound impact on gas-phase tracer TTL composition during AMMA. We find the amount of photochemically aged air isentropically mixed into the TTL across the subtropical tropopause to be not significant. Using the N2O observations we estimate the fraction of aged extratropical stratospheric air in the TTL to be 0.0±0.1 up to 370 K during the local flights. Above the TTL this fraction increases to 0.3±0.1 at 390 K. The subtropical barrier, as indicated by the slope of the correlation between N2O and O3 between 415 and 490 K, does not appear as a sharp border between the tropics and extratropics, but rather as a gradual transition region between 10° N and 25° N where isentropic mixing between these two regions may occur.

  9. Observation of a tropopause fold by MARA VHF wind-profiler radar and ozonesonde at Wasa, Antarctica: comparison with ECMWF analysis and a WRF model simulation

    Directory of Open Access Journals (Sweden)

    M. Mihalikova

    2012-09-01

    Full Text Available Tropopause folds are one of the mechanisms of stratosphere–troposphere exchange, which can bring ozone rich stratospheric air to low altitudes in the extra-tropical regions. They have been widely studied at northern mid- or high latitudes, but so far almost no studies have been made at mid- or high southern latitudes. The Moveable Atmospheric Radar for Antarctica (MARA, a 54.5 MHz wind-profiler radar, has operated at the Swedish summer station Wasa, Antarctica (73° S, 13.5° W during austral summer seasons from 2007 to 2011 and has observed on several occasions signatures similar to those caused by tropopause folds at comparable Arctic latitudes. Here a case study is presented of one of these events when an ozonesonde successfully sampled the fold. Analysis from European Center for Medium Range Weather Forecasting (ECMWF is used to study the circumstances surrounding the event, and as boundary conditions for a mesoscale simulation using the Weather Research and Forecasting (WRF model. The fold is well resolved by the WRF simulation, and occurs on the poleward side of the polar jet stream. However, MARA resolves fine-scale layering associated with the fold better than the WRF simulation.

  10. Observation of a tropopause fold by MARA VHF wind-profiler radar and ozonesonde at Wasa, Antarctica: comparison with ECMWF analysis and a WRF model simulation

    Science.gov (United States)

    Mihalikova, M.; Kirkwood, S.; Arnault, J.; Mikhaylova, D.

    2012-09-01

    Tropopause folds are one of the mechanisms of stratosphere-troposphere exchange, which can bring ozone rich stratospheric air to low altitudes in the extra-tropical regions. They have been widely studied at northern mid- or high latitudes, but so far almost no studies have been made at mid- or high southern latitudes. The Moveable Atmospheric Radar for Antarctica (MARA), a 54.5 MHz wind-profiler radar, has operated at the Swedish summer station Wasa, Antarctica (73° S, 13.5° W) during austral summer seasons from 2007 to 2011 and has observed on several occasions signatures similar to those caused by tropopause folds at comparable Arctic latitudes. Here a case study is presented of one of these events when an ozonesonde successfully sampled the fold. Analysis from European Center for Medium Range Weather Forecasting (ECMWF) is used to study the circumstances surrounding the event, and as boundary conditions for a mesoscale simulation using the Weather Research and Forecasting (WRF) model. The fold is well resolved by the WRF simulation, and occurs on the poleward side of the polar jet stream. However, MARA resolves fine-scale layering associated with the fold better than the WRF simulation.

  11. A novel tropopause-related climatology of ozone profiles

    NARCIS (Netherlands)

    Sofieva, V.F.; Tamminen, J.; Kyrola, E.; Mielonen, T.; Veefkind, J.P.; Hassler, B.; Bodeker, G.E.

    2014-01-01

    A new ozone climatology, based on ozonesonde and satellite measurements, spanning the altitude region between the earth's surface and ~60 km is presented (TpO3 climatology). This climatology is novel in that the ozone profiles are categorized according to calendar month, latitude and local tropopaus

  12. Variations in Extratropical Cyclone Activity in Northern East Asia

    Institute of Scientific and Technical Information of China (English)

    WANG Xinmin; ZHAI Panmao; WANG Cuicui

    2009-01-01

    Based on an improved objective cyclone detection and tracking algorithm, decadal variations in extratropical cyclones in northern East Asia are studied by using the ECMWF 40 Year Reanalysis (ERA-40) sea-level pressure data during 1958-2001. The results reveal that extratropical cyclone activity has displayed clear seasonal, interannual, and decadal variability in northern East Asia. Spring is the season when cyclones occur most frequently. The spatial distribution of extratropical cyclones shows that cyclones occur mainly within the 40°-50°N latitudinal band in northern East Asia, and the most frequent region of occurrence is in Mongolia. Furthermore, this study also reveals the fact that the frequency of extratropical cyclones has significantly decreased in the lower latitude region of northern East Asia during 1958-2001, but dccadal variability has dominated in higher latitude bands, with frequent cyclone genesis. The intensity of extratropical cyclones has decreased on an annual and seasonal basis. Variation of the annual number of cyclones in northern East Asia is associated with the mean intensity of the baroclinic frontal zone, which is influenced by climate warming in the higher latitudes. Moreover, the dipole structure of extratopical cyclone change, with increases in the north and decreases in the southern part of northern East Asia, is related to the northward movement of the baroclinic frontal zone on either side of 110°E.

  13. Data denial experiments for extratropical transition

    Directory of Open Access Journals (Sweden)

    Doris Anwender

    2012-11-01

    Full Text Available Data denial experiments using the European Centre for Medium-Range Weather Forecasts (ECMWF model are designed to investigate the value of targeted observations for historical extratropical transition (ET cases over the Atlantic. The impact of removing data from specified locations linked to the ET development is therefore examined. It is shown that the impact of denying data in the near tropical cyclone (TC environment is, on average, as important as denying data in mid-latitude sensitive regions determined using extratropical singular vectors (SV. The impact of data denial over TC regions propagates downstream from the Atlantic towards Europe, with a maximum degradation at day 4. This degradation is mainly attributed to the data denial at the TC stage, i.e. before ET is completed. When data are denied on mid-latitude sensitive regions, the largest degradation is found around day 2 and also after the day 4 forecast. In general, the loss of information content is larger when data are denied in mid-latitude sensitive areas because these identify dynamically active regions. In both denial experiments, aircraft and satellite radiance data are the most influential observations. For the selected case of Hurricane Irene, the largest degradations are found for forecasts initialised while Irene reached its peak intensity. If observations are denied in the near storm environment, the TC mostly disappears from the analysis and the subsequent forecast. This allows the impact of Irene on the formation of the downstream cut-off low to be investigated.

  14. Evidence of horizontal and vertical transport of water in the Southern Hemisphere tropical tropopause layer (TTL) from high-resolution balloon observations

    Science.gov (United States)

    Khaykin, Sergey M.; Pommereau, Jean-Pierre; Riviere, Emmanuel D.; Held, Gerhard; Ploeger, Felix; Ghysels, Melanie; Amarouche, Nadir; Vernier, Jean-Paul; Wienhold, Frank G.; Ionov, Dmitry

    2016-09-01

    High-resolution in situ balloon measurements of water vapour, aerosol, methane and temperature in the upper tropical tropopause layer (TTL) and lower stratosphere are used to evaluate the processes affecting the stratospheric water budget: horizontal transport (in-mixing) and hydration by cross-tropopause overshooting updrafts. The obtained in situ evidence of these phenomena are analysed using satellite observations by Aura MLS (Microwave Limb Sounder) and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) together with trajectory and transport modelling performed using CLaMS (Chemical Lagrangian Model of the Stratosphere) and HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model. Balloon soundings were conducted during March 2012 in Bauru, Brazil (22.3° S) in the frame of the TRO-Pico campaign for studying the impact of convective overshooting on the stratospheric water budget. The balloon payloads included two stratospheric hygrometers: FLASH-B (Fluorescence Lyman-Alpha Stratospheric Hygrometer for Balloon) and Pico-SDLA instrument as well as COBALD (Compact Optical Backscatter Aerosol Detector) sondes, complemented by Vaisala RS92 radiosondes. Water vapour vertical profiles obtained independently by the two stratospheric hygrometers are in excellent agreement, ensuring credibility of the vertical structures observed. A signature of in-mixing is inferred from a series of vertical profiles, showing coincident enhancements in water vapour (of up to 0.5 ppmv) and aerosol at the 425 K (18.5 km) level. Trajectory analysis unambiguously links these features to intrusions from the Southern Hemisphere extratropical stratosphere, containing more water and aerosol, as demonstrated by MLS and CALIPSO global observations. The in-mixing is successfully reproduced by CLaMS simulations, showing a relatively moist filament extending to 20° S. A signature of local cross-tropopause transport of water is observed in a particular

  15. Impact of different vertical transport representations on simulating processes in the tropical tropopause layer (TTL)

    Energy Technology Data Exchange (ETDEWEB)

    Ploeger, Felix

    2011-07-06

    The chemical and dynamical processes in the tropical tropopause layer (TTL) control the amount of radiatively active species like water vapour and ozone in the stratosphere, and hence turn out to be crucial for atmospheric trends and climate change. Chemistry transport models and chemistry climate models are suitable tools to understand these processes. But model results are subject to uncertainties arising from the parametrization of model physics. In this thesis the sensitivity of model predictions to the choice of the vertical transport representation will be analysed. Therefore, backtrajectories are calculated in the TTL, based on different diabatic and kinematic transport representations using ERA-Interim and operational ECMWF data. For diabatic transport on potential temperature levels, the vertical velocity is deduced from the ERA-Interim diabatic heat budget. For kinematic transport on pressure levels, the vertical wind is used as vertical velocity. It is found that all terms in the diabatic heat budget are necessary to cause transport from the troposphere to the stratosphere. In particular, clear-sky heating rates alone miss very important processes. Many characteristics of transport in the TTL turn out to depend very sensitively on the choice of the vertical transport representation. Timescales for tropical troposphere-to-stratosphere transport vary between one and three months, with respect to the chosen representation. Moreover, for diabatic transport ascent is found throughout the upper TTL, whereas for kinematic transport regions of mean subsidence occur, particularly above the maritime continent. To investigate the sensitivity of simulated trace gas distributions in the TTL to the transport representation, a conceptual approach is presented to predict water vapour and ozone concentrations from backtrajectories, based on instantaneous freeze-drying and photochemical ozone production. It turns out that ozone predictions and vertical dispersion of the

  16. On the Development of Above-Anvil Cirrus Plumes in Extratropical Convection

    Science.gov (United States)

    Homeyer, C. R.; McAuliffe, J. D.; Bedka, K. M.

    2016-12-01

    Expansive cirrus clouds present above the anvils of extratropical convection have been observed in satellite and aircraft-based imagery for several decades. Despite knowledge of their occurrence, the precise mechanisms and atmospheric conditions leading to their formation and maintenance are not entirely known. Here, we examine the formation of these cirrus "plumes" using a combination of satellite imagery, three-dimensional ground-based radar observations, assimilated atmospheric states from a state-of-the-art reanalysis, and idealized numerical simulations with explicitly resolved convection. Using data from ten recent cases (2013-Present), we find that all storms with above-anvil cirrus plumes reach altitudes 1 to 6 km above the tropopause. Thus, it is likely that these clouds represent the injection of cloud material into the lower stratosphere. Comparison of above-anvil cirrus plume cases with ten additional cases of observed tropopause-penetrating convection without plumes reveals that these clouds are associated with large vector differences between the motion of a storm and the environmental wind in the upper troposphere and lower stratosphere (UTLS), suggesting that gravity wave breaking and/or stretching of the tropopause-penetrating cloud are/is more prevalent in plume-producing storms. No relationship is found between above-anvil cirrus plume occurrence and the stability of the lower stratosphere (or tropopause structure) or the duration of stratospheric penetration. Idealized model simulations of tropopause-penetrating convection with small and large magnitudes of storm-relative wind in the UTLS are found to reproduce the established observational relationship and show that frequent gravity wave breaking is the primary mechanism responsible for above-anvil cirrus plume formation.

  17. Extratropical cyclone classification and its use in climate studies

    Science.gov (United States)

    Catto, J. L.

    2016-06-01

    Extratropical cyclones have long been known to be important for midlatitude weather. It is therefore important that our current state-of-the-art climate models are able to realistically represent these features, in order that we can have confidence in how they are projected to change in a warming climate. Despite the observation that these cyclones are extremely variable in their structure and features, there have, over the years, been numerous attempts to classify or group them. Such classifications can provide insight into the different cloud structures, airflows, and dynamical forcing mechanisms within the different cyclone types. This review collects and details as many classification techniques as possible, and may therefore act as a reference guide to classifications. These classifications offer the opportunity to improve the way extratropical cyclone evaluation in climate models is currently done by giving more insight into the dynamical and physical processes that occur in climate models (rather than just evaluating the mean state over a broad region as is often done). Examples of where these ideas have been used, or could be used, are reviewed. Finally, the potential impacts of future climate changes on extratropical cyclones are detailed. The ways in which the classification techniques could improve our understanding of future changes in extratropical cyclones and their impacts are given.

  18. Long-term variations in outgoing long-wave radiation (OLR), convective available potential energy (CAPE) and temperature in the tropopause region over India

    Indian Academy of Sciences (India)

    R Sapra; S K Dhaka; V Panwar; R Bhatnagar; K Praveen Kumar; Y Shibagaki; M Venkat Ratnam; M Takahashi

    2011-10-01

    Relationship of outgoing long-wave radiation (OLR) with convective available potential energy (CAPE) and temperature at the 100-hPa pressure level is examined using daily radiosonde data for a period 1980–2006 over Delhi (28.3° N, 77.1°E) and Kolkata (22.3°N, 88.2°E), and during 1989–2005 over Cochin (10°N, 77°E) and Trivandrum (8.5°N, 77.0°E), India. Correlation coefficient (xy) between monthly OLR and CAPE shows a significant (∼ −0.45) anti-correlation at Delhi and Kolkata suggesting low OLR associated with high convective activity during summer (seasonal variation). Though, no significant correlation was found between OLR and CAPE at Cochin and Trivandrum (low latitude region); analysis of OLR and temperature (at 100-hPa) association suggests that low OLR peaks appear corresponding to low temperature at Delhi (xy ∼ 0.30) and Kolkata (xy ∼ 0.25) during summer. However, xy between OLR and temperature becomes opposite as we move towards low latitudes (∼8° – 10°N) due to strong solar cycle influence. Large scale components mainly ENSO and quasi-biennial oscillaton (QBO) that contributed to the 100-hPa temperature variability were also analyzed, which showed that ENSO variance is larger by a factor of two in comparison to QBO over Indian region. ENSO warm conditions cause warming at 100-hPa over Delhi and Darwin. However, due to strong QBO and solar signals in the equatorial region, ENSO signal seems less effective. QBO, ENSO, and solar cycle contribution in temperature are found location-dependent (latitudinal variability) responding in consonance with shifting in convective activity regime during El Niño, seasonal variability in the tropical easterly jet, and the solar irradiance.

  19. Airborne Tropical TRopopause EXperiment (ATTREX) 2014 Western Pacific Campaign

    Science.gov (United States)

    Jensen, E.; Pfister, L.

    2014-01-01

    The NASA Airborne Tropical TRopopause EXperiment (ATTREX) is a series of airborne campaigns focused on understanding physical processes in the Tropical Tropopause Layer (TTL) and their role in atmospheric chemistry and climate. ATTREX is using the high-altitude, long-duration NASA Global Hawk Unmanned Air System to make in situ and remote-sensing measurements spanning the Pacific. A particular ATTREX emphasis is to better understand the dehydration of air as it passes through the cold tropical tropopause region. The ATTREX payload contains 12 in situ and remote sensing instruments that measure water vapor, carbon dioxide, methane, nonmethane hydrocarbons, sulfur hexafluoride, chlorofluorocarbons, nitrous oxide), reactive chemical compounds (ozone, bromine, nitrous oxide), meteorological parameters, and radiative fluxes. During January-March, 2014, the Global Hawk was deployed to Guam for ATTREX flights. Six science flights were conducted from Guam (in addition to the transits across the Pacific), resulting in over 100 hours of Western Pacific TTL sampling and about 180 vertical profiles through the TTL. I will provide an overview of the dataset, with examples of the measurements including meteorological parameters, clouds and water vapor, and chemical tracers.

  20. Aerosol vertical distribution, new particle formation, and jet aircraft particle emissions in the free troposhere and tropopause region; Vertikalverteilung und Neubildungsprozesse des Aerosols und partikelfoermige Flugzeugemissionen in der freien Troposphaere und Tropopausenregion

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, F.P.

    2000-07-01

    A contribution to the understanding of natural and anthropogenously induced particle formation as well as aerosol physical transformation processes within the free troposphere (FT) is introduced. Documentation and interpretation of empirical data relevant with respect to possible climatologic impact of anthropogenous aerosol emissions into the atmosphere is presented. The first section describes new technique for high spatial resolution measurements of ultrafine aerosol particles by condensation nucleus counters (CNCs), a necessary prerequisite for the observation of natural particle formation and jet aircraft emissions. The second section illustrates vertical distribution and variability ranges of the aerosol in the FT and the tropopause region (TP). Typical microphysical states of the atmospheric aerosol within the Northern Hemisphere are documented by means of systematic measurements during more than 60 flight missions. Simple mathematical parameterizations of the aerosol vertical distribution and aerosol size distributions are developed. Important aerosol sources within the FT are localized and possible aerosol formation processes are discussed. The third section is focussed on jet-engine particle emissions within the FT and TP. A unique inflight experiment for detection of extremely high concentrations (>10{sup 6} cm{sup -3}) of extremely small (donw to <3 nm) aerosols inside the exhaust plumes of several jet aircraft is described. Particle emission indices and emission-controlling parameters are deduced. Most important topic is the impact of fuel sulfur content of kerosine on number, size and chemical composition of jet particle emissions. Generalized results are parameterized in form of lognormal aerosol particle size distributions. (orig.) [German] Ein Beitrag zum Verstaendnis natuerlicher und anthropogen induzierter Aerosolneubildung sowie physikalischer Aerosolumwandlung in der freien Troposphaere wird vorgestellt. Empirisch gewonnenes Datenmaterial wird

  1. Extra-tropical origin of equatorial Pacific cold bias in climate models

    Science.gov (United States)

    Burls, N.; Muir, L.; Vincent, E. M.; Fedorov, A. V.

    2015-12-01

    General circulation models frequently suffer from a substantial cold bias in equatorial Pacific sea surface temperatures (SSTs). For instance, the majority of the climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) have this particular problem (17 out of the 26 models evaluated in this project). Our study investigates the extent to which these equatorial cold biases are related to mean climate biases generated in the extra-tropics and then communicated to the equator via the oceanic subtropical cells (STCs). With an evident relationship across the CMIP5 models between equatorial SSTs and upper ocean temperatures in the extra-tropical subduction regions, our analysis confirms that cold SST biases within the extra-tropical Pacific translate into a cold equatorial SST bias via the STCs. An assessment of the relationship between these extra-tropical SST biases and surface heat flux components indicates a link to biases in the simulated shortwave fluxes. Further sensitivity studies with a climate model (CESM) in which extra-tropical cloud albedo is systematically varied illustrate the influence of cloud albedo perturbations, not only directly above the oceanic subduction regions but across the extended extra-tropical Pacific, on the equatorial bias. The CESM experiments reveal a quadratic relationship between extra-tropical albedo and the root-mean-square-error in equatorial SSTs - a relationship with which the CMIP5 models generally agree. Thus, our study suggests that one way to improve the equatorial cold bias is to improve the representation of cloud albedo in mid-latitudes.

  2. Tropopause inversion layer formation and stratosphere-troposphere exchange during idealized baroclinic wave life cycle experiments

    Science.gov (United States)

    Kunkel, Daniel; Wirth, Volkmar; Hoor, Peter

    2014-05-01

    Recent simulations of baroclinic wave life cycles revealed that the tropopause inversion layer (TIL), commonly situated just above the thermal tropopause, is evident in such experiments and emerges after the onset of wave breaking. Furthermore, bidirectional stratosphere-troposphere exchange (STE) occurs during this non-linear stage of the wave evolution and might be affected by the appearance of the TIL. We study the evolution and the impact of the TIL on STE by using the COSMO model in an idealized mid-latitude channel geometry configuration without physical sub-grid scale parameterizations. We initialize the model with a geostrophically balanced upper level jet stream which is disturbed by an anomaly of potential vorticity to trigger the evolution of the baroclinic waves. Moreover, we use passive tracers of tropospheric or stratospheric origin to identify regions of potential STE. Our results show that the static stability is low in regions of stratosphere to troposphere exchange (STT), while it is high in regions dominated by exchange in the opposite direction (TST). Furthermore, inertia gravity waves, originating from regions with strong ageostrophic wind components, modulate the static stability as well as the vertical shear of the horizontal wind near and above the tropopause. While propagating away from their source, the inertia gravity waves lead to large values of the squared Brunt Vaisala frequency in regions which are simultaneously characterized by low bulk Richardson numbers. Thus, these regions are statically stable and turbulent at the same time and might be crucial for TST, thereby explaining tropospheric mixing ratio changes of e.g. CO across the tropopause which commonly change from tropospheric to stratospheric values a few hundred meters above the local thermal tropopause.

  3. Diagnosing the transition layer in the extra-tropical lowermost stratosphere using MLS O3 and MOPITT CO analyses

    Directory of Open Access Journals (Sweden)

    V.-H. Peuch

    2012-08-01

    Full Text Available The behavior of the Extra-tropical Transition Layer (ExTL in the lowermost stratosphere is investigated using a Chemistry Transport Model (CTM and analyses derived from assimilation of MLS (Microwave Limb Sounder O3 and MOPITT (Measurements Of Pollution In The Troposphere CO data. We use O3-CO correlations to quantify the effect of the assimilation on the height and depth of the ExTL. We firstly focus on a Stratosphere-Troposphere Exchange (STE case study which occurred on 15 August 2007 over the British Isles (50° N, 10° W. We also extend the study at the global scale for the month of August 2007. For the STE case study, MOPITT CO analyses have the capability to sharpen the ExTL distribution whereas MLS O3 analyses provide a tropospheric expansion of the ExTL distribution with its maximum close to the thermal tropopause. When MLS O3 and MOPITT CO analyses are used together, the ExTL shows more realistic results and matches the thermal tropopause. At global scale, MOPITT CO analyses still show a sharper chemical transition between stratosphere and troposphere than the free model run. MLS O3 analyses move the ExTL toward the troposphere and broaden it. When MLS O3 analyses and MOPITT CO analyses are used together the ExTL matches the thermal tropopause poleward of 50°. This study shows that data assimilation can help overcome the shortcomings associated with a relatively coarse model resolution. The ExTL spread is larger in the Northern Hemisphere than the Southern Hemisphere suggesting that mixing processes are more active in the UTLS in the Northern Hemisphere than in the Southern Hemisphere. This work opens perspectives for studying the seasonal variations of the ExTL at extra-tropical latitudes.

  4. The Tropical UTLS JAPE Bubble and its Role Driving Extratropical Weather

    Science.gov (United States)

    Tripoli, G. J.; Nytes, L.

    2015-12-01

    Latent heating by tropical weather systems produces vertical mass fluxes of high potential temperature that fill upper isentropic layers with mass. This produces an expanded isentropic layer in the tropical Upper troposphere - Lower Stratosphere (UTLS) of elevated potential energy. Because this elevated potential energy is converted to kinetic energy if it flows poleward, we call it JAPE (Jet Available Potential Energy). This conversion effectively prevents wholesale movement into the extratropics, an effect of inertial stability due to the Earth's rotation. As a result, the JAPE takes the form of a potential energy bubble spanning heights between 10 km and 18 km and meridionally between 30N and 30S on average with occasional poleward plumes reaching up to 50 degrees latitude. The JAPE bubble is bounded on its poleward edge by the subtropical jet (STJ) and its upper surface by the elevated tropical tropopause. As potential energy is continually fed into the bubble by tropical convective and tropical cyclone activity, the JAPE bubble builds mass and an increasing potential to surge that mass into the extratropics, leading to "JAPE surge" events. These events occur at weaknesses in the inertial wall of the bubble, usually related to interactions with a polar jet. These surges become energy conduits, infusing the JAPE (and reducing the bubble mass) into the extratropical Rossby wave stream via a STJ-PJ interaction. The poleward JAPE surge events are periodic and occur in 3-5 locations simultaneously around the globe, usually in the winter hemisphere. At the oral presentation, a 36 year analysis of the behavior of the JAPE bubble will be presented, and its role in energizing the Rossby wave train will be discussed.

  5. Development of an Extratropical Storm Wind, Wave, and Water Level Climatology for the Offshore Mid-Atlantic

    Science.gov (United States)

    2015-08-01

    ER D C/ CH L TR -1 5- 11 Development of an Extratropical Storm Wind , Wave, and Water Level Climatology for the Offshore Mid-Atlantic...Development of an Extratropical Storm Wind , Wave, and Water Level Climatology for the Offshore Mid-Atlantic Michael F. Forte Field Research Facility...of the extreme offshore wind , wave, and water level climate in the mid-Atlantic region has been conducted for the U.S. Bureau of Safety and

  6. Extratropical North Atlantic SST influence on Sahel rainfall

    Science.gov (United States)

    Liu, Y.; Chiang, J. C.

    2013-12-01

    We present evidence suggesting that the late 1960's Sahel drought was linked to an abrupt cooling in the extratropical North Atlantic, whose influence was then propagated to the Sahel by atmospheric teleconnection. Such linkages have been observed in paleoclimate during abrupt climate changes of the last glacial period. They have also occurred in coupled model simulations of Atlantic meridional overturning circulation (AMOC) slowdown, the latter being the leading cause of said paleoclimate abrupt changes. The AMOC-slowdown simulations show a characteristic global pattern of climate changes, including a northern hemispheric-wide cooling and increased surface pressure, and weakening of the West African and Asian monsoons. We show that an observed northern-hemispheric pattern of changes, resembling the AMOC slowdown, occurred during the late 1960's, co-incident with the Sahel drought. A combined principal component analysis of 20th century surface temperature, sea level pressure and precipitation extracts a leading mode whose spatial pattern closely resemble the impacts of AMOC slowdown. A similar analysis of AMIP-type simulations forced by 20th century observed forcings shows a similar result, suggesting that the origins of the climate change reside in SST changes, in particular over extratropical North Atlantic. Taken together, the results suggests the influence of extratropical North Atlantic cooling on the 20th century Sahel drought, and a teleconnection pathway through surface/tropospheric cooling. Motivated by our observational result, we investigated atmospheric teleconnection mechanisms of extratropical North Atlantic cooling in an atmospheric general circulation model (GCM) coupled with slab ocean. Our results indicate the central role of tropospheric cooling in communicating the influence on the Sahel. We explicitly show this using regional climate model simulation of the Sahel, with air temperature and associated humidity anomalies from the GCM simulation

  7. Deep convective clouds at the tropopause

    Directory of Open Access Journals (Sweden)

    H. H. Aumann

    2010-07-01

    Full Text Available Data from the Advanced Infrared Sounder (AIRS on the EOS Aqua spacecraft identify thousands of cloud tops colder than 225 K, loosely referred to as Deep Convective Clouds (DCC. Many of these cloud tops have "inverted" spectra, i.e. areas of strong water vapor, CO2 and ozone opacity, normally seen in absorption, are now seen in emission. We refer to these inverted spectra as DCCi. They are found in about 0.4% of all spectra from the tropical oceans excluding the Western Tropical Pacific (WTP, 1.1% in the WTP. The cold clouds are the anvils capping thunderstorms and consist of optically thick cirrus ice clouds. The precipitation rate associated with DCCi suggests that imbedded in these clouds, protruding above them, and not spatially resolved by the AIRS 15 km FOV, are even colder bubbles, where strong convection pushes clouds to within 5 hPa of the pressure level of the tropopause cold point. Associated with DCCi is a local upward displacement of the tropopause, a cold "bulge", which can be seen directly in the brightness temperatures of AIRS and AMSU channels with weighting function peaking between 40 and 2 hPa, without the need for a formal temperature retrieval. The bulge is not resolved by the analysis in numerical weather prediction models. The locally cold cloud tops relative to the analysis give the appearance (in the sense of an "illusion" of clouds overshooting the tropopause and penetrating into the stratosphere. Based on a simple model of optically thick cirrus clouds, the spectral inversions seen in the AIRS data do not require these clouds to penetrate into the stratosphere. However, the contents of the cold bulge may be left in the lower stratosphere as soon as the strong convection subsides. The heavy precipitation and the distortion of the temperature structure near the tropopause indicate that DCCi are associated with intense storms. Significant long-term trends in the statistical properties of DCCi could be

  8. Objectively classifying Southern Hemisphere extratropical cyclones

    Science.gov (United States)

    Catto, Jennifer

    2016-04-01

    There has been a long tradition in attempting to separate extratropical cyclones into different classes depending on their cloud signatures, airflows, synoptic precursors, or upper-level flow features. Depending on these features, the cyclones may have different impacts, for example in their precipitation intensity. It is important, therefore, to understand how the distribution of different cyclone classes may change in the future. Many of the previous classifications have been performed manually. In order to be able to evaluate climate models and understand how extratropical cyclones might change in the future, we need to be able to use an automated method to classify cyclones. Extratropical cyclones have been identified in the Southern Hemisphere from the ERA-Interim reanalysis dataset with a commonly used identification and tracking algorithm that employs 850 hPa relative vorticity. A clustering method applied to large-scale fields from ERA-Interim at the time of cyclone genesis (when the cyclone is first detected), has been used to objectively classify identified cyclones. The results are compared to the manual classification of Sinclair and Revell (2000) and the four objectively identified classes shown in this presentation are found to match well. The relative importance of diabatic heating in the clusters is investigated, as well as the differing precipitation characteristics. The success of the objective classification shows its utility in climate model evaluation and climate change studies.

  9. Characteristics of Double Tropopause Layers Observed During TORERO

    Science.gov (United States)

    Haggerty, J. A.; Mahoney, M. J.; Campos, T. L.; Pierce, B.; Volkamer, R. M.

    2012-12-01

    The existence of double tropopauses is indicated in data collected during the Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated VOC (TORERO) experiment in January - February 2012. Airborne remote and in situ measurements from the NSF/NCAR Gulfstream V place tropopause heights at ~12-13 km and ~16-17 km during oceanic flights westward and southward from Antofagasta, Chile. Coastal radiosonde profiles confirm the locations of these tropopause layers. Various measurements define and characterize the transition layer between the upper troposphere and lower stratosphere. The Microwave Temperature Profiler (MTP), a scanning radiometer which measures emitted radiation at three frequencies, provides temperature vertical structure over a layer several kilometers above and below the aircraft with vertical resolution sufficient to resolve the tropopause. Tropopause height as determined from the temperature profile is based on the cold point and lapse rate transitions. In situ measurements of trace gases such as ozone, carbon monoxide, and water vapor also provide distinct signatures at the tropopause, although the aircraft did not always reach sufficient altitudes to detect the second tropopause. Model profiles of temperature and trace gases were also generated by the Real-time Air Quality Modeling System (RAQMS) during TORERO. RAQMS is a global meteorological, chemical and aerosol assimilation/forecasting system that assimilates real-time stratospheric ozone retrievals from the Microwave Limb Sounder (MLS), total column ozone from the Ozone Monitoring Instrument (OMI), and aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS). In this paper, observations of the TORERO double tropopause features as defined by temperature and trace gas profiles are presented and compared to model-defined tropopause properties.

  10. Extra-tropical origin of equatorial Pacific cold bias in climate models with links to cloud albedo

    Science.gov (United States)

    Burls, Natalie J.; Muir, Leslie; Vincent, Emmanuel M.; Fedorov, Alexey

    2017-09-01

    General circulation models frequently suffer from a substantial cold bias in equatorial Pacific sea surface temperatures (SSTs). For instance, the majority of the climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) have this particular problem (17 out of the 26 models evaluated in the present study). Here, we investigate the extent to which these equatorial cold biases are related to mean climate biases generated in the extra-tropics and then communicated to the equator via the oceanic subtropical cells (STCs). With an evident relationship across the CMIP5 models between equatorial SSTs and upper ocean temperatures in the extra-tropical subduction regions, our analysis suggests that cold SST biases within the extra-tropical Pacific indeed translate into a cold equatorial bias via the STCs. An assessment of the relationship between these extra-tropical SST biases and local surface heat flux components indicates a link to biases in the simulated shortwave fluxes. Further sensitivity studies with a climate model (CESM) in which extra-tropical cloud albedo is systematically varied illustrate the influence of cloud albedo perturbations, not only directly above the oceanic subduction regions but across the extra-tropics, on the equatorial bias. The CESM experiments reveal a quadratic relationship between extra-tropical Pacific albedo and the root-mean-square-error in equatorial SSTs—a relationship with which the CMIP5 models generally agree. Thus, our study suggests that one way to improve the equatorial cold bias in the models is to improve the representation of subtropical and mid-latitude cloud albedo.

  11. Extra-tropical origin of equatorial Pacific cold bias in climate models with links to cloud albedo

    Science.gov (United States)

    Burls, Natalie J.; Muir, Leslie; Vincent, Emmanuel M.; Fedorov, Alexey

    2016-11-01

    General circulation models frequently suffer from a substantial cold bias in equatorial Pacific sea surface temperatures (SSTs). For instance, the majority of the climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) have this particular problem (17 out of the 26 models evaluated in the present study). Here, we investigate the extent to which these equatorial cold biases are related to mean climate biases generated in the extra-tropics and then communicated to the equator via the oceanic subtropical cells (STCs). With an evident relationship across the CMIP5 models between equatorial SSTs and upper ocean temperatures in the extra-tropical subduction regions, our analysis suggests that cold SST biases within the extra-tropical Pacific indeed translate into a cold equatorial bias via the STCs. An assessment of the relationship between these extra-tropical SST biases and local surface heat flux components indicates a link to biases in the simulated shortwave fluxes. Further sensitivity studies with a climate model (CESM) in which extra-tropical cloud albedo is systematically varied illustrate the influence of cloud albedo perturbations, not only directly above the oceanic subduction regions but across the extra-tropics, on the equatorial bias. The CESM experiments reveal a quadratic relationship between extra-tropical Pacific albedo and the root-mean-square-error in equatorial SSTs—a relationship with which the CMIP5 models generally agree. Thus, our study suggests that one way to improve the equatorial cold bias in the models is to improve the representation of subtropical and mid-latitude cloud albedo.

  12. Economic costs of extratropical storms under climate change: An application of FUND

    Science.gov (United States)

    Narita, D.; Tol, R.; Anthoff, D.

    2009-12-01

    Extratropical cyclones have attracted some attention in climate policy circles as a possible significant damage factor of climate change. This study conducts an assessment of economic impacts of increased storm activities under climate change with the integrated assessment model FUND 3.5. FUND is a model that calculates damages of climate change for 16 regions by making use of exogenous scenarios of socioeconomic variables (for details of our estimation approach, see our working paper whose URL is indicated below). Our estimation shows that in the base case, the direct economic damage of enhanced storms due to climate change amounts to $2.8 billion globally (approximately 38% of the total economic loss of storms at present) at the year 2100, while the ratio to the world GDP is 0.0009%. The regional results (Figure 1) indicate that the economic effect of extratropical storms with climate change would have relatively minor importance for the US (USA): The enhanced extratropical storm damage (less than 0.001% of GDP for the base case) is one order of magnitude lower than the tropical cyclone damage (roughly 0.01% GDP) calculated by the same version of FUND. In the regions without strong tropical cyclone influence, such as Western Europe (WEU) and Australia and New Zealand (ANZ), the extratropical storms might have some more significance as a possible damage factor of climate change. Especially for the latter, the direct economic damage could amount to more than 0.006% of GDP. Still, the impact is small relative to the income growth expected in these regions. Figure 1. Increased direct economic loss at the year 2100 for selected regions (results are shown for the three different baselines: the years 1986-2005, 1976-2005, and 1996-2005). US - USA; Canada - CAN; Western Europe - WEU; Australia and New Zealand - ANZ.

  13. Extratropical cyclones and the projected decline of winter Mediterranean precipitation in the CMIP5 models

    OpenAIRE

    Zappa, Giuseppe; Hawcroft, Matthew K; Shaffrey, Len; Black, Emily; Brayshaw, David J.

    2015-01-01

    The Mediterranean region has been identified as a climate change "hot-spot" due to a projected reduction in precipitation and fresh water availability which has potentially large socio-economic impacts. To increase confidence in these projections, it is important to physically understand how this precipitation reduction occurs. This study quantifies the impact on winter Mediterranean precipitation due to changes in extratropical cyclones in 17 CMIP5 climate models. In each model, the extratro...

  14. Tropical response to extratropical eastward propagating waves

    Directory of Open Access Journals (Sweden)

    S. Sridharan

    2015-06-01

    Full Text Available Space–time spectral analysis of ERA-interim winds and temperature at 200 hPa for December 2012–February 2013 shows the presence of eastward propagating waves with period near 18 days in mid-latitude meridional winds at 200 hPa. The 18 day waves of k = 1–2 are dominantly present at latitudes greater than 80°, whereas the waves of k = 3–4 are dominant at 60° of both Northern and Southern Hemispheres. Though the 18 day wave of smaller zonal wavenumbers (k = 1–2 are confined to high latitudes, there is an equatorward propagation of the 18 day wave of k = 4 and 5. The wave amplitude of k = 5 is dominant than that of k = 4 at tropical latitudes. In the Northern Hemisphere (NH, there is a poleward tilt in the phase of the wave of k = 5 at mid-latitudes, as height increases indicating the baroclinic nature of the wave, whereas in the Southern Hemisphere (SH, the wave has barotropic structure as there is no significant phase variation with height. At the NH subtropics, the wave activity is confined to 500–70 hPa with moderate amplitudes. It is reported for the first time that the wave of similar periodicity (18 day and zonal structure (k = 5 as that of extratropical wave disturbance has been observed in tropical OLR, a proxy for tropical convection. We suggest that the selective response of the tropical wave forcing may be due to the lateral forcing of the eastward propagating extratropical wave of similar periodicity and zonal structure.

  15. A Lagrangian view of convective sources for transport of air across the Tropical Tropopause Layer: distribution, times and the radiative influence of clouds

    Directory of Open Access Journals (Sweden)

    A. Tzella

    2011-12-01

    Full Text Available The tropical tropopause layer (TTL is a key region controlling transport between the troposphere and the stratosphere. The efficiency of transport across the TTL depends on the continuous interaction between the large-scale advection and the small-scale intermittent convection that reaches the Level of Zero radiative Heating (LZH. The wide range of scales involved presents a significant challenge to determine the sources of convection and quantify transport across the TTL. Here, we use a simple Lagrangian model, termed TTL detrainment model, that combines a large ensemble of 200-day back trajectory calculations with high-resolution fields of brightness temperatures (provided by the CLAUS dataset in order to determine the ensemble of trajectories that are detrained from convective sources. The trajectories are calculated using the ECMWF ERA-Interim winds and radiative heating rates, and in order to establish the radiative influence of clouds, the latter rates are derived both under all-sky and clear-sky conditions.

    We show that most trajectories are detrained near the mean LZH with the horizontal distributions of convective sources being highly-localized, even within the space defined by deep convection. As well as modifying the degree of source localization, the radiative heating from clouds facilitates the rapid upwelling of air across the TTL. However, large-scale motion near the fluctuating LZH can lead a significant proportion of trajectories to alternating clear-sky and cloudy regions, thus generating a large dispersion in the vertical transport times. The distributions of vertical transport times are wide and skewed and are largely insensitive to a bias of about ±1 km (∓5 K in the altitude of cloud top heights (the main sensitivity appearing in the times to escape the immediate neighbourhood of the LZH while some seasonal and regional transport characteristics are apparent for times up to 60 days. The strong horizontal

  16. CYGNSS Observations of Surface Wind Speeds in Oceanic Tropical and Extratropical Cyclones

    Science.gov (United States)

    Posselt, D. J.; Crespo, J.; Naud, C. M.

    2016-12-01

    The Cyclone Global Navigation Satellite System (CYGNSS) mission is the first of the new generation of NASA Earth Venture missions, and consists of a constellation of eight small satellites scheduled for launch in November 2016. The mission utilizes GPS signals reflected from the Earth's surface to infer near-surface wind speeds over the global tropical oceans. The eight-satellite constellation will observe ocean-surface wind speeds in all weather conditions (including in heavy precipitation) with a median revisit time of approximately 3 hours. While CYGNSS is designed to measure wind speeds in the inner core of tropical cyclones, it will observe near-surface winds over all oceanic regions within the span of its orbit. The orbit inclination is 35 degrees, which means that the satellite will observe primarily the tropics and sub-tropics; however, because the antennae are angled 28 degrees off-nadir, the effective range of latitudes spans -40 to 40 degrees. As such, CYGNSS will observe regions known to be characterized by rapid extratropical cyclone development (e.g., the southern portion of the Gulf Stream off the U.S. East Coast). In this presentation, we discuss CYGNSS sampling characteristics, with an eye toward its potential to observe winds not only in tropical cyclones, but in extratropical cyclones as well. We simulate orbits over a historical extratropical storm, and also utilize a multi-year database of cyclone centers to determine CYGNSS sampling characteristics integrated over many storms.

  17. Long-term behavior of the Kelvin waves revealed by CHAMP/GPS RO measurements and their effects on the tropopause structure

    Directory of Open Access Journals (Sweden)

    M. Venkat Ratnam

    2006-07-01

    Full Text Available The vertical and temporal variations of Kelvin waves and the associated effects on the tropical tropopause were studied using long-term (from May 2001 to October 2005 CHAMP/GPS (CHAllenging Mini satellite Payload/Global Positioning System radio occultation (RO measurements. The periods of these waves were found to be varying in between 10 and 15 days, with vertical wavelengths 5–8 km. These variations clearly show eastward phase propagation in the time-longitude section and eastward phase tilts with height in altitude-longitude, displaying the characteristics of Kelvin waves. The peak variance in the temperature is found over the Indian Ocean and into the western Pacific within the broad region of the equator. Kelvin wave amplitudes were found significantly enhanced in the eastward shear of the quasi-biennial oscillation (QBO and are confined in and around the tropopause during westward phase of QBO, where it extends between 17 and 25 km during the eastward phase of QBO and is damped away above, consistent with earlier reported results. The amplitudes are increasing during the months of Northern Hemisphere winter and sometimes they are highly sporadic in nature. Seasonal and inter-annual variations in the Kelvin wave amplitudes near the tropical tropopause coincide exactly with the tropopause height and temperature, with a sharp tropopause during maximum Kelvin wave activity. A clear annual oscillation, along with a month-to-month coincidence is evident most of the time in both the tropopause height and Kelvin wave activity, with maximum and minimum Kelvin wave amplitudes during the Northern Hemisphere winter and summer, respectively. In addition, a signature of quasi-biennial oscillation (QBO in the tropopause structure is also seen in long-term tropopause variations, although the amplitudes are less when compared to the annual oscillation. In the westward phase of QBO (during strong Kelvin wave activity at 20km (in 2001–2002 winter and

  18. Tropopause characteristics and variability from 11 yr of SHADOZ observations in the southern tropics and subtropics

    CSIR Research Space (South Africa)

    Sivakumar, V

    2011-07-01

    Full Text Available from 83 radiosonde stations around the globe to study tropo- pause climatological characteristics. They studied the CPT, LRT, and PLT on the basis of temperature in- formation over Northern and Southern Hemisphere regions and found that the annual... 2001). Forster and Tourpali (2001) analyzed ozonesonde data at 11 Northern Hemisphere sites and found tropopause height increases of 330?520 m on the basis of data from 1970 to 1996/97. Santer et al. (2003) reported a global tropo- pause trend...

  19. Contribution of mixing to upward transport across the tropical tropopause layer (TTL

    Directory of Open Access Journals (Sweden)

    P. Konopka

    2007-06-01

    Full Text Available During the second part of the TROCCINOX campaign that took place in Brazil in early 2005, chemical species were measured on-board the high-altitude research aircraft Geophysica (ozone, water vapor, NO, NOy, CH4 and CO in the altitude range up to 20 km (or up to 450 K potential temperature, i.e. spanning the entire TTL region roughly extending between 350 and 420 K.

    Here, analysis of transport across the TTL is performed using a new version of the Chemical Lagrangian Model of the Stratosphere (CLaMS. In this new version, the stratospheric model has been extended to the earth surface. Above the tropopause, the isentropic and cross-isentropic advection in CLaMS is driven by meteorological analysis winds and heating/cooling rates derived from a radiation calculation. Below the tropopause, the model smoothly transforms from the isentropic to the hybrid-pressure coordinate and, in this way, takes into account the effect of large-scale convective transport as implemented in the vertical wind of the meteorological analysis. As in previous CLaMS simulations, the irreversible transport, i.e. mixing, is controlled by the local horizontal strain and vertical shear rates.

    Stratospheric and tropospheric signatures in the TTL can be seen both in the observations and in the model. The composition of air above ≈350 K is mainly controlled by mixing on a time scale of weeks or even months. Based on CLaMS transport studies where mixing can be completely switched off, we deduce that vertical mixing, mainly driven by the vertical shear in the tropical flanks of the subtropical jets and, to some extent, in the the outflow regions of the large-scale convection, offers an explanation for the upward transport of trace species from the main convective outflow at around 350 K up to the tropical tropopause around 380 K.

  20. Contribution of mixing to upward transport across the tropical tropopause layer (TTL)

    Science.gov (United States)

    Konopka, P.; Günther, G.; Müller, R.; Dos Santos, F. H. S.; Schiller, C.; Ravegnani, F.; Ulanovsky, A.; Schlager, H.; Volk, C. M.; Viciani, S.; Pan, L. L.; McKenna, D.-S.; Riese, M.

    2007-06-01

    During the second part of the TROCCINOX campaign that took place in Brazil in early 2005, chemical species were measured on-board the high-altitude research aircraft Geophysica (ozone, water vapor, NO, NOy, CH4 and CO) in the altitude range up to 20 km (or up to 450 K potential temperature), i.e. spanning the entire TTL region roughly extending between 350 and 420 K. Here, analysis of transport across the TTL is performed using a new version of the Chemical Lagrangian Model of the Stratosphere (CLaMS). In this new version, the stratospheric model has been extended to the earth surface. Above the tropopause, the isentropic and cross-isentropic advection in CLaMS is driven by meteorological analysis winds and heating/cooling rates derived from a radiation calculation. Below the tropopause, the model smoothly transforms from the isentropic to the hybrid-pressure coordinate and, in this way, takes into account the effect of large-scale convective transport as implemented in the vertical wind of the meteorological analysis. As in previous CLaMS simulations, the irreversible transport, i.e. mixing, is controlled by the local horizontal strain and vertical shear rates. Stratospheric and tropospheric signatures in the TTL can be seen both in the observations and in the model. The composition of air above ≍350 K is mainly controlled by mixing on a time scale of weeks or even months. Based on CLaMS transport studies where mixing can be completely switched off, we deduce that vertical mixing, mainly driven by the vertical shear in the tropical flanks of the subtropical jets and, to some extent, in the the outflow regions of the large-scale convection, offers an explanation for the upward transport of trace species from the main convective outflow at around 350 K up to the tropical tropopause around 380 K.

  1. Synoptic and climatological aspects of extra-tropical cyclones

    Science.gov (United States)

    Leckebusch, G. C.

    2010-09-01

    Mid-latitude cyclones are highly complex dynamical features embedded in the general atmospheric circulation of the extra-tropics. Although the basic mechanisms leading to the formation of cyclones are commonly understood, the specific conditions and physical reasons triggering extreme, partly explosive development, are still under investigation. This includes also the identification of processes which might modulate the frequency and intensity of cyclone systems on time scales from days to centennials. This overview presentation will thus focus on three main topics: Firstly, the dynamic-synoptic structures of cyclones, the possibility to objectively identify cyclones and wind storms, and actual statistical properties of cyclone occurrence under recent climate conditions are addressed. In a second part, aspects of the interannual variability and its causing mechanisms are related to the seasonal predictability of extreme cyclones producing severe storm events. Extending the time frame will mean to deduce information on decadal or even centennial time periods. Thus, actual work to decadal as well as climatological variability and changes will be presented. In the last part of the talk focus will be laid on potential socio-economical impacts of changed cyclone occurrence. By means of global and regional climate modeling, future damages in terms of insured losses will be investigated and measures of uncertainty estimated from a multi-model ensemble analysis will be presented.

  2. Diagnostics of the Tropical Tropopause Layer from in-situ observations and CCM data

    Directory of Open Access Journals (Sweden)

    E. Palazzi

    2009-05-01

    Full Text Available A suite of diagnostics is applied to in-situ aircraft measurements and one Chemistry-Climate Model (CCM data to characterize the vertical structure of the Tropical Tropopause Layer (TTL. The diagnostics are based on the vertical tracers profiles, relative vertical tracers gradients, and tracer-tracer relationships in the tropical Upper Troposphere/Lower Stratosphere (UT/LS, using tropopause coordinates.

    Observations come from the four tropical campaigns performed from 1998 to 2006 with the research aircraft Geophysica and have been directly compared to the output of the ECHAM5/MESSy CCM. The model vertical resolution in the TTL allows for appropriate comparison with high-resolution aircraft observations and the diagnostics used highlight common TTL features between the model and the observational data.

    The analysis of the vertical profiles of water vapour, ozone, and nitrous oxide, in both the observations and the model, shows that concentration mixing ratios exhibit a strong gradient change across the tropical tropopause, due to the role of this latter as a transport barrier and that transition between the tropospheric and stratospheric regimes occurs within a finite layer. The use of relative vertical ozone gradients, in addition to the vertical profiles, helps to highlight the region where this transition occurs and allows to give an estimate of its thickness. The analysis of the CO-O3 and H2O-O3 scatter plots and of the Probability Distribution Function (PDF of the H2O-O3 pair completes this picture as it allows to better distinguish tropospheric and stratospheric regimes that can be identified, first, by their differing chemical composition.

    The joint analysis and comparison of observed and modelled data allows us to evaluate the capability of the model in reproducing the observed vertical structure of the TTL and its variability, and also to assess whether

  3. The structure and maintenance of tropopause polar vortices over the Arctic

    Science.gov (United States)

    Cavallo, Steven M.

    2009-12-01

    Tropopause polar vortices (TPVs) are coherent vortices based the tropopause in polar regions, where they are isolated from the wind shear associated with the midlatitude jet stream. Cyclonic TPVs are a common feature of the Arctic, have radii up to 1500 km, and can have lifetimes of over one month. The Arctic is a particularly favorable region for these features due to the isolation from the jet stream, an environment conducive for vortex longevity. Further, TPVs can have an impact on surface weather since they provide more favorable conditions for surface cyclogenesis. The intensification of cyclonic TPVs is examined using an Ertel Potential Vorticity (EPV) framework to test the hypothesis that diabatic effects are able to intensify the vortices due to a dominance of radiative cooling within the vortices that can be seen in high latitudes. This thesis first generalizes the diabatic intensification mechanisms by applying the EPV framework methods to a large sample of cyclones in the Canadian Arctic, and shows that there is a net tendency to create EPV in the vortex, and hence intensify cyclones from radiative processes. While the effects of latent heating are considerable, they are smaller in magnitude. The physical mechanisms leading to these observations are then examined in idealized numerical experiments, where it is shown that longwave radiative cooling is the most important mechanism for intensification. Dry air from the downward intrusion of stratospheric air in the vortex strengthens the vertical gradient of water vapor near the tropopause, and weakens the vertical gradient of water vapor in the lower stratosphere. This results in relatively high radiative cooling near the tropopause, and relatively low radiative cooling in the lower stratosphere with respect to the background environment in the vortex core, enhancing EPV generation in the vortex core. The impact of radiative processes to the climatology of cyclonic TPVs is then examined by comparing a

  4. Impact of horizontal spatial resolution on the derivation of the source receptor relationship—an extra-tropical cyclone case

    Science.gov (United States)

    Lee, Jae-Bum; Lee, Tae-Young

    2004-11-01

    A numerical study has been made to evaluate the impact of horizontal resolution on the estimation of the source receptor (S R) relationship. Numerical experiments with four different horizontal grid sizes have been performed for an extra-tropical cyclonic episode in East Asia. CSU RAMS and YU-SADM (Yonsei University's sulfuric acid deposition model) have been used to simulate meteorological and pollutant fields, respectively.In this study, enhanced spatial resolution has improved the simulation of an extra-tropical cyclone, cold front and associated precipitation systems. As spatial resolution increases, the circulation associated with the cyclone and cold front becomes stronger, and the amount of frontal rainfall increases. This study has shown that enhancement of spatial resolution tends to increase self-contributions but decrease foreign contributions to the wet deposition associated with an extra-tropical cyclone. It has been found that increased precipitation for enhanced spatial resolution reduces the amount of transported pollutant but increases the wet deposition of locally emitted pollutants. The larger self-contribution for higher resolutions may also be partially due to the increased strength of resolved convection. The impact of enhancing spatial resolution on dry deposition is felt mostly over downstream regions where the centres of the lows and fronts pass. Contributions from upstream sources increase as cyclonic circulation becomes stronger with increasing spatial resolution. On the other hand, enhancing spatial resolution does not significantly affect the S R relationship for either dry or wet deposition in the other regions where the extra-tropical cyclone does not pass. This study indicates that improved simulation of a cold front does not significantly affect the S R relationship for wet deposition over the area of passage of the cold front. An additional discussion infers a S R relationship for the wet deposition associated with a typical extra-tropical

  5. A Study of Extratropical Transition and Re-Intensification of Typhoon Mindulle (2004)

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiande; WANG Qi; FU Gang; LIU Yulong; TIAN Ying

    2011-01-01

    In this study,the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSUNCAR) Mesoscale Model (MM5) is used to simulate Typhoon Mindulle (2004) at high resolution (3-km grid size).The data from measurements show that in the upper atmosphere the existence of an upper jet is important to the transition cyclone.When Mindulle moved to the area of the upper jet entrance,where high-altitude divergence existed,the pumping of the high-altitude divergence would enhance the vertical motion and low-level cyclone convergence.The enhanced vertical motion was confirmed by the simulation results and indicated that the existence of upper divergence enhanced the vertical motion which was favorable for the maintenance of Typhoon Mindulle.The process of extratropical transition (ET) and re-intensification always accompanies the process of cold air invasion.This process enhances the baroclinicity of the atmosphere and the formation of front at high altitudes,which converts baroclinic potential energy into kinetic energy and strengthens the cyclone vortex.The distributions of equivalent potential temperature (θe) and temperature anomalies show that the warm-core of the typhoon at the tropopause aids the re-intensification of the system.As the typhoon reenters the ocean,latent heat flux (LHF) increases in the north and west and the strong reflectivity and vertical motion occur in the east and southeast,and the west.With the re-intensification of the typhoon the wind field evolves from an oval to a circle at the lower atmosphere,the area coverage by high winds increases,and the distribution of the tangential wind shows an asymmetric pattern.

  6. The vertical sulfur dioxide distribution at the tropopause level

    Science.gov (United States)

    Meixner, F. X.

    A sensitive chemiluminescence measurement method consisting of separate sampling and analysis stages and the application of a wet chemical filter procedure has been used to measure SO2 over western Europe at aircraft altitudes of up to 15 km. These measurements indicate that meteorological conditions at the tropopause have an important influence on the observed SO2 mixing ratio, and that increasing SO2 mixing ratios within the first km of the stratosphere give strong support to the suggestion of a stratospheric SO2 source. The Crutzen (1981) and Turco, et al. (1981) one-dimensional models, which take the vertical distribution of S compounds into consideration, indicate that the oxidation of such organic S compounds as OCS and CS2 may be the stratospheric source of SO2. Flux calculations based on tropopausal SO2 mixing ratios imply a merely minor anthropogenic SO2 contribution to the stratospheric aerosol layer.

  7. Modelling deep convection and its impacts on the tropical tropopause layer

    Directory of Open Access Journals (Sweden)

    J. S. Hosking

    2010-08-01

    Full Text Available The UK Met Office's Unified Model is used at a high global resolution (N216, ~0.83° × ~0.56°, ~60 km to assess the impact of deep tropical convection on the structure of the tropical tropopause layer (TTL. We focus on the potential for rapid transport of short-lived ozone depleting species to the stratosphere by rapid convective uplift. The modelled horizontal structure of organised convection is shown to match closely with signatures found in the OLR satellite data. In the model, deep convective elevators rapidly lift air from 4–5 km up to 12–14 km. The influx of tropospheric air entering the TTL (11–12 km is similar for all tropical regions with most convection stopping below ~14 km. The tropical tropopause is coldest and driest between November and February, coinciding with the greatest upwelling over the tropical warm pool. As this deep convection is co-located with bromine-rich biogenic coastal emissions, this period and location could potentially be the preferential gateway for stratospheric bromine.

  8. On the Relationship between Tropical Moisture Exports and Extratropical Cyclones

    Science.gov (United States)

    Knippertz, Peter; Wernli, Heini; Gläser, Gregor; Boleti, Eirini; Joos, Hanna; Binder, Hanin

    2016-04-01

    Tropical moisture export (TME) events are an important element of the global circulation and contribute significantly to regional precipitation. They are defined here on the basis of trajectories starting in the tropical troposphere and reaching a water vapor flux of at least 100 g kg-1 m s-1 poleward of 35° latitude. TME frequency shows four marked occurrence maxima in both hemispheres with varying seasonal cycles. In some cases TMEs can be linked to similar phenomena of atmospheric flow such as Warm Conveyor Belts (WCBs) or Atmospheric Rivers (ARs). For example, 90% of all ARs affecting the US West Coast during December-May are connected to TME events, but the tropical moisture source is less important during the more active AR season June-November. In addition to these climatological TME characteristics we discuss two aspects of their relationship to extratropical cyclones: Case studies indicate that (i) cyclones traveling along the southern fringes of the midlatitude storm track can instigate the export of tropical moisture ahead of their cold fronts, and (ii) the tropical moisture can fuel latent heat release in the cyclone and therefore contribute to its intensification. A long-term statistical analysis of passages of TME trajectories through areas with closed isobars surrounding active cyclones in the northern hemisphere reveals a surprisingly small number of encounters, particularly in winter. The majority of hits occur south of 40°N and there is no statistically significant relationship with cyclone intensification. The results suggest that TMEs often pass relatively far from cyclone centers where vertical motions tend to be moderate. This prevents an early rainout of the tropical moisture and allows the export into higher latitudes. For the same reasons we expect TMEs to "avoid" WCBs with roots at low latitudes. This interpretation is consistent with the fact that most TME maxima are located along the western flanks of subtropical high-pressure systems.

  9. A Study of the Extratropical Transformation of Typhoon Winnie (1997)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The complicated evolutive process of how a tropical cyclone transforms into an extratropical cyclone is still an unresolved issue to date, especially one which arises in a weakly baroclinic environment. Typhoon Winnie (1997) is studied during its extratropical transformation stage of extratropical transition (ET)with observational data and numerical simulations. Results show that Winnie experienced its extratropical transformation to the south of the subtropical high without intrusion of the mid-latitude baroclinic zone.This is significantly different from previous studies. Analyses reveal that the cold air, which appeared in the north edge of Winnie circulation, resulted from the precipitation drag and cooling effect of latent heat absorption associated with the intense precipitation there. The cooling only happened below 3 km and the greatest cooling was below 1 km. With the cold air and its advection by the circulation of Winnie, a front was formed in the lower troposphere. The front above is related not only to the cooling in the lower level but also to the warming effect of latent heat release in the middle-upper levels. The different temperature variation in the vertical caused the temperature gradient over Winnie and resulted in the baroclinicity.

  10. Indian MST radar: A remote sensing tool for studying long- and short- term cross tropopause transports

    Science.gov (United States)

    Das, Siddarth Shankar; Ratnam, Madineni Venkat; Suneeth, K. V.

    The stratospheric air is dry and ozone rich in nature, whereas the tropospheric air is enriched in humidity with high aerosol concentration. The tropopause is the stable layer which acts as a semi-permeable membrane between these two spheres (i.e. troposphere and stratosphere) and thus hinders the exchange of the minors constituents (e.g. water vapour and ozone) between these two spheres. This complex equilibrium region is known as the upper troposphere and lower stratosphere (UTLS) region. The major mixing process befalls over the tropical region, where the maximum convective systems occur through the tropical tropopause layer (TTL). Thus, it is necessary to understand the dynamical and chemical processes that occurring at UTLS region and quantative analysis of the mass exchange is essential. Ten years of data obtained from Indian MST radar located at a Tropical station Gadanki (13.5oN, 79.2oE) is used to study the long- and short (event) term cross tropopause transport. The prime mechanisms responsible for the radar backscattering echoes are isotropic/anisotropic turbulence fluctuations in the refractive index and Fresnel reflection/scattering due to sharp gradients in the radio refractive index. The inhomogeneties in the radio refractive index are contributed by both humidity and temperature below 8 km height, whereas above it, it is only contributed by the temperature gradients. When the dry stratospheric air penetrates into the troposphere, it will take some time to mix with the humid air of troposphere. Due to two different constituents of the air, there will be strong refractive index gradient, which will be reflected as enhanced radar backscattering echoes. The dry stratospheric air will slowly mix with the humid tropospheric air by means of small scale turbulence. Using this scattering mechanism behavior, the long-term and its seasonal characteristics, and the short-term event wise (convective disturbances) stratospheric air intrusion into the troposphere

  11. Improved Satellite Techniques for Monitoring and Forecasting the Transition of Hurricanes to Extratropical Storms

    Science.gov (United States)

    Folmer, Michael; Halverson, Jeffrey; Berndt, Emily; Dunion, Jason; Goodman, Steve; Goldberg, Mitch

    2014-01-01

    The Geostationary Operational Environmental Satellites R-Series (GOES-R) and Joint Polar Satellite System (JPSS) Satellite Proving Grounds have introduced multiple proxy and operational products into operations over the last few years. Some of these products have proven to be useful in current operations at various National Weather Service (NWS) offices and national centers as a first look at future satellite capabilities. Forecasters at the National Hurricane Center (NHC), Ocean Prediction Center (OPC), NESDIS Satellite Analysis Branch (SAB) and the NASA Hurricane and Severe Storms Sentinel (HS3) field campaign have had access to a few of these products to assist in monitoring extratropical transitions of hurricanes. The red, green, blue (RGB) Air Mass product provides forecasters with an enhanced view of various air masses in one complete image to help differentiate between possible stratospheric/tropospheric interactions, moist tropical air masses, and cool, continental/maritime air masses. As a compliment to this product, a new Atmospheric Infrared Sounder (AIRS) and Cross-track Infrared Sounder (CrIS) Ozone product was introduced in the past year to assist in diagnosing the dry air intrusions seen in the RGB Air Mass product. Finally, a lightning density product was introduced to forecasters as a precursor to the new Geostationary Lightning Mapper (GLM) that will be housed on GOES-R, to monitor the most active regions of convection, which might indicate a disruption in the tropical environment and even signal the onset of extratropical transition. This presentation will focus on a few case studies that exhibit extratropical transition and point out the usefulness of these new satellite techniques in aiding forecasters forecast these challenging events.

  12. Diagnostics of the Tropical Tropopause Layer from in-situ observations and CCM data

    Directory of Open Access Journals (Sweden)

    C. M. Volk

    2009-12-01

    Full Text Available A suite of diagnostics is applied to in-situ aircraft measurements and one Chemistry-Climate Model (CCM data to characterize the vertical structure of the Tropical Tropopause Layer (TTL. The diagnostics are based on vertical tracer profiles and relative vertical tracer gradients, using tropopause-referenced coordinates, and tracer-tracer relationships in the tropical Upper Troposphere/Lower Stratosphere (UT/LS.

    Observations were obtained during four tropical campaigns performed from 1999 to 2006 with the research aircraft Geophysica and have been compared to the output of the ECHAM5/MESSy CCM. The model vertical resolution in the TTL (~500 m allows for appropriate comparison with high-resolution aircraft observations and the diagnostics used highlight common TTL features between the model and the observational data.

    The analysis of the vertical profiles of water vapour, ozone, and nitrous oxide, in both the observations and the model, shows that concentration mixing ratios exhibit a strong gradient change across the tropical tropopause, due to the role of this latter as a transport barrier and that transition between the tropospheric and stratospheric regimes occurs within a finite layer. The use of relative vertical ozone and carbon monoxide gradients, in addition to the vertical profiles, helps to highlight the region where this transition occurs and allows to give an estimate of its thickness. The analysis of the CO-O3 and H2O-O3 scatter plots and of the Probability Distribution Function (PDF of the H2O-O3 pair completes this picture as it allows to better distinguish tropospheric and stratospheric regimes that can be identified by their different chemical composition.

    The joint analysis and comparison of observed and modelled data allows to state that the model can represent the background TTL structure and its seasonal variability rather accurately. The model

  13. Diagnostics of the Tropical Tropopause Layer from in-situ observations and CCM data

    Science.gov (United States)

    Palazzi, E.; Fierli, F.; Cairo, F.; Cagnazzo, C.; di Donfrancesco, G.; Manzini, E.; Ravegnani, F.; Schiller, C.; D'Amato, F.; Volk, C. M.

    2009-12-01

    A suite of diagnostics is applied to in-situ aircraft measurements and one Chemistry-Climate Model (CCM) data to characterize the vertical structure of the Tropical Tropopause Layer (TTL). The diagnostics are based on vertical tracer profiles and relative vertical tracer gradients, using tropopause-referenced coordinates, and tracer-tracer relationships in the tropical Upper Troposphere/Lower Stratosphere (UT/LS). Observations were obtained during four tropical campaigns performed from 1999 to 2006 with the research aircraft Geophysica and have been compared to the output of the ECHAM5/MESSy CCM. The model vertical resolution in the TTL (~500 m) allows for appropriate comparison with high-resolution aircraft observations and the diagnostics used highlight common TTL features between the model and the observational data. The analysis of the vertical profiles of water vapour, ozone, and nitrous oxide, in both the observations and the model, shows that concentration mixing ratios exhibit a strong gradient change across the tropical tropopause, due to the role of this latter as a transport barrier and that transition between the tropospheric and stratospheric regimes occurs within a finite layer. The use of relative vertical ozone and carbon monoxide gradients, in addition to the vertical profiles, helps to highlight the region where this transition occurs and allows to give an estimate of its thickness. The analysis of the CO-O3 and H2O-O3 scatter plots and of the Probability Distribution Function (PDF) of the H2O-O3 pair completes this picture as it allows to better distinguish tropospheric and stratospheric regimes that can be identified by their different chemical composition. The joint analysis and comparison of observed and modelled data allows to state that the model can represent the background TTL structure and its seasonal variability rather accurately. The model estimate of the thickness of the interface region between tropospheric and stratospheric regimes

  14. Stratosphere-troposphere exchange in a summertime extratropical low: analysis

    OpenAIRE

    2006-01-01

    Ozone and carbone monoxide measurements sampled during two commercial flights in airstreams of a summertime midlatitude cyclone are analysed with a lagrangian-based study (backward trajectories and a Reverse Domain Filling technique) to gain a comprehensive understanding of transport effects on trace gas distributions. The study demonstrates that summertime cyclones can be associated with deep stratosphere-troposphere transport. A tropopause fold is sampled twice in its life cycle, once in th...

  15. The Effect of Tropopause Seeing on Solar Telescope Site Testing

    Science.gov (United States)

    Beckers, Jacques M.

    2017-08-01

    The site testing for and seeing correction planning of the 4-m solar telescopes has failed to take into account the significant amount of seeing at tropopause levels (10-20 km altitude).The worst aspect of that seeing layer is its small isoplanatic patch size which at low solar elevations can be significantly less than 1 arcsec. The CLEAR/ATST/DKIST SDIMM seeing monitor is insensitive to this type of seeing. A correction for this missed seeing significantly decreases the measured seeing qualities for the sites tested especially in the early morning and late afternoon. It clearly shows the lake site to be superior with mid-day observations much to be preferred. The small tropopause isoplanatic patch size values also complicate the implementation of the solar MCAO systems aimed at large field-of-view sun imaging. Currently planned systems only correct for lower-layer seeing for which the isoplanatic patch size is about one arc minute. To fully achieve the diffraction limit of the 4-meter class (0.025 arcsec at 500 nm), over a large enough field-of-view to be of scientific interest, complicated Multi-Conjugate Adaptive Optics systems will be needed.

  16. Southern annular mode: tropical-extratropical interactions and impacts

    CSIR Research Space (South Africa)

    Fauchereau, N

    2009-09-01

    Full Text Available ?Dept.,?University?of?Cape?Town,?South?Africa 1.?Introduction The?Southern?Annular?Mode?(SAM,?also?called?Antarctic? Oscillation)?is?the?dominant?mode?of?extratropical?(south? of ? 20S) ? low?frequency ? atmospheric ? variability ? ? in ? the? Southern?Hemisphere.?It ?basically...?with?a?seasonally?adjusted?principal?component? index,?17th?Climate?diagnostics?workshop,?Norman,?OK,? 52?57. ...

  17. Impact of the observed extratropics on climatological simulations of the MJO in a tropical channel model

    Science.gov (United States)

    Hall, Nicholas M. J.; Thibaut, Séverin; Marchesiello, Patrick

    2016-06-01

    A regional model is used to quantify the influence of the extratropics on simulated tropical intraseasonal variability. The Weather Research and Forecasting (WRF) model is run in tropical channel mode with the boundaries at 30° N and S constrained to 6-hourly reanalysis data. Experiments with modified boundary conditions are carried out in which intraseasonal (20-100 days) timescales are removed, or in which only the annual and diurnal cycles are retained. Twin runs are used to give an objective measure of the boundary-independant component of the variance in each case. The model captures MJO-like propagating structures and shows greater zonal-wind variance in runs with full boundary conditions. Comparison between experiments indicates that about half the intraseasonal variance can be attributed to boundary influence, and specifically to the presence of an intraseasonal extratropical signal. This signal is associated with stronger correlations between low-level zonal wind precursors in the Pacific sector and Indian Ocean convective events. Temporal coherence between MJO events in the model and the observations is analysed by defining four phases based on convectively coupled signals in the low-level zonal wind. The model can only match observed events above the level of chance when intraseasonal boundary information is provided. Results are analysed in terms of `primary' and `successive' events. Although the model hindcast skill is generally poor, it is better for successive events.

  18. Stratospheric water vapour budget and convection overshooting the tropopause: modelling study from SCOUT-AMMA

    Directory of Open Access Journals (Sweden)

    X. M. Liu

    2010-09-01

    Full Text Available The aim of this paper is to study the impacts of overshooting convection at a local scale on the water distribution in the tropical UTLS. Overshooting convection is assumed to be one of the processes controlling the entry of water vapour mixing ratio in the stratosphere by injecting ice crystals above the tropopause which later sublimate and hydrate the lower stratosphere. For this purpose, we quantify the individual impact of two cases of overshooting convection in Africa observed during SCOUT-AMMA: the case of 4 August 2006 over Southern Chad which is likely to have influenced the water vapour measurements by micro-SDLA and FLASH-B from Niamey on 5 August, and the case of a mesoscale convective system over Aïr on 5 August 2006. We make use of high resolution (down to 1 km horizontally nested grid simulations with the three-dimensional regional atmospheric model BRAMS (Brazilian Regional Atmospheric Modelling System. In both cases, BRAMS succeeds in simulating the main features of the convective activity, as well as overshooting convection, though the exact position and time of the overshoots indicated by MSG brightness temperature difference is not fully reproduced (typically 1° displacement in latitude compared with the overshoots indicated by brightness temperature difference from satellite observations for both cases, and several hours shift for the Aïr case on 5 August 2006. Total water budgets associated with these two events show a significant injection of ice particles above the tropopause with maximum values of about 3.7 ton s−1 for the Chad case (4 August and 1.4 ton s−1 for the Aïr case (5 August, and a total upward cross tropopause transport of about 3300 ton h−1 for the Chad case and 2400 ton h−1 for the Aïr case in the third domain of simulation. The order of magnitude of these modelled fluxes is lower but comparable with similar studies in other tropical areas based on

  19. Did the Nabro volcanic eruption directly overshoot the tropopause?

    Science.gov (United States)

    Biondi, Riccardo; Steiner, Andrea K.; Kirchengast, Gottfried; Brenot, Hugues; Rieckh, Therese

    2015-04-01

    During the night of 12 to 13 June 2011 an explosive eruption occurred at the Nabro volcano located in Eritrea (13.4°N, 41.7°E). This has been recognized as the largest volcanic eruption since Pinatubo 1991, ejecting ash and sulfur dioxide (SO2) into the atmosphere, spreading over more than 60 degrees in latitude and more than 100 degrees in longitude within a few days and lasting for more than 15 days. While there is agreement on the fact that the eruptive mass reached the stratosphere, the processes bringing the cloud to the lower stratosphere are still much debated. For solving this issue we used about 300 atmospheric profiles from Global Positioning System (GPS) Radio Occultation (RO) observations and analyzed the pre-eruption conditions and the impact of the eruption itself on the tropospheric and stratospheric thermal structure. The GPS RO technique enables measurements of the atmospheric parameters in nearly any meteorological condition, with global coverage, high vertical resolution and high accuracy, making RO data well suited to study the thermodynamic structure of volcanic clouds and their impact on climate. In the Nabro area there are no ground based measurements that can be used for such kind of studies and, in the period of the eruption, there are no acquisitions by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. By analyzing the RO bending angle anomaly in the volcanic cloud area, we evaluated the cloud top altitude and compared it to the tropopause altitude (also derived from RO) in the same area. Moreover, we analyzed the RO temperature profiles before and after the eruption. Our results show that the volcanic cloud directly overshoot the tropopause and that the injected SO2 warmed the lower stratosphere in an area of about 10x10 degrees in latitude and longitude for 6 months, which is consistent with the effect found on a larger scale for the Pinatubo eruption in 1991. This study shows the capabilities

  20. Impact of deep convection in the tropical tropopause layer in West Africa: in-situ observations and mesoscale modelling

    OpenAIRE

    Fierli, F.; E. Orlandi; Law, K. S.; C. Cagnazzo; Borrmann, S.; F. Cairo; Schiller, C.; F. Ravegnani; Volk, M

    2011-01-01

    We present the analysis of the impact of convection on the composition of the tropical tropopause layer region (TTL) in West-Africa during the AMMA-SCOUT campaign. Geophysica M55 aircraft observations of water vapor, ozone, aerosol and CO2 during August 2006 show perturbed values at altitudes ranging from 14 km to 17 km (above the main convective outflow) and satellite data indicates that air detrainment is likely to have originated from convective cloud east of the flights. Simulations of th...

  1. Multiscale Variability of the Tropopause Transition Layer During AMIE

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Richard H. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Atmospheric Science; Birner, Thomas [Colorado State Univ., Fort Collins, CO (United States). Dept. of Atmospheric Science

    2016-11-28

    An investigation has been carried out of the influence of the Madden-Julian Oscillation on the tropical tropopause layer (TTL) using data from the ARM MJO Investigation Experiment (AMIE) during the period October-November 2011. A variety of data from the ARM Mobile Facility deployed during AMIE on Gan Island have been used in the study: 3-hourly atmospheric soundings, the Ka-band ARM Zenith Radar (KAZR) radar reflectivity fields, and the ARM PI-Product CombRet (Combined Retrieval, Microphysical Retrievals, and Heating Rates) produced by PNNL. Additional data used in the study are from CALIPSO, ERAi reanalyses, DYNAMO (Dynamics of the MJO) sounding network observations, the S-PolKa radar on Gan Island, and the DOE ARM sites at Manus and Nauru.

  2. The exchange across the tropical tropopause in overshooting convective cores

    Energy Technology Data Exchange (ETDEWEB)

    Rao, T.N.; Radhakrishna, B.; Mohan Satyanarayana, T.; Satheesh Kumar, S. [National Atmospheric Research Lab., Gadanki (India)

    2010-07-01

    Coordinated measurements of Indian MST radar and radiosonde during the passage of overshooting convective cores in SAFAR pilot campaign (May-November 2008) are utilized to quantify the mass flux across the tropopause and strength of the turbulence in up- and down-draft cores. The distribution of retrieved mass flux is found to be wide, ranging from -0.6 (downward flux) to 0.8 kg m{sup -2}s{sup -1} (upward flux). The net mass flux, is, however, from the troposphere to stratosphere, in spite of the existence of significant amount of downward flux. For the first time, the turbulence strength in the vicinity of the tropopause in convective cores is quantified. Large spectral widths with magnitudes >4 ms{sup -1} are observed during convection. However, such large spectral widths are rare and are observed only for 1.6% of total observations. The average spectral width (and also the variation or standard deviation) in draft cores is found to be {proportional_to}4.5 times larger than that in fair-weather. The turbulence strength in updraft cores is much higher than that of in downdraft cores. The mean (median) spectral width in updraft cores is larger by {proportional_to}0.8 ms{sup -1} (a factor of {proportional_to}2) than that of in downdraft cores. The turbulence strength does not show any systematic variation with the intensity of convection in both up- and down-draft cores. The distributions and mean values of mass flux and turbulence strength obtained in the present study will be useful to quantify the STE due to direct intrusion of mass by overshooting convection and the exchange of constituents (in particular water vapor) due to turbulence in a better way. (orig.)

  3. Dynamics of transient upwelling across the tropical tropopause

    Science.gov (United States)

    Randel, W. J.; Abalos, M.

    2013-12-01

    Tropical upwelling is a fundamental component of the stratospheric Brewer Dobson circulation (BDC), influencing temperatures, water vapor and chemical constituents throughout the global stratosphere. There is a substantial component of sub-seasonal variability in upwelling, with strong effects on temperatures and tracers in the tropical lower stratosphere. Upwelling diagnosed using momentum balance calculations from ERAinterim data demonstrate that transience is linked to the effects of extratropical wave forcing, with centers of action in the high latitude winter stratosphere and in the subtropical upper troposphere of both hemispheres. Zonal mean wind tendencies are an important part of communicating the remote wave forcing to the deep tropics. Dynamical patterns reflect clear differences in forcing the shallow vs. deep branches of the BDC; the shallow branch is most correlated with wave forcing in the subtropical upper troposphere, while the deep branch is mainly influenced by high latitude planetary waves.

  4. Extratropical influences on the inter-annual variability of South-Asian monsoon

    Science.gov (United States)

    Syed, F. S.; Yoo, J. H.; Körnich, H.; Kucharski, F.

    2012-04-01

    The effects of extratropical dynamics on the interannual variations in South-Asian Monsoon (SAM) are examined. Based on NCEP/NCAR reanalysis and CRU precipitation data, a conditional maximum covariance analysis is performed on sea level pressure, 200 hPa geopotential heights and the SAM rainfall by removing the linear effects of El-Niño Southern Oscillation from the fields. It is found that two modes provide a strong connection between the upper-level circulation in the Atlantic/European region and SAM rainfall: the Circumglobal Teleconnection (CGT) and the Summer North Atlantic Oscillation (SNAO). The structures in the 200 hPa heights of both modes in the Atlantic region are similar in the Atlantic region, and their southeastward extension to South Asia (SA) also corresponds to upper-level ridges (in their positive phases) in slightly different positions. Nevertheless, the influence of both modes on SAM rainfall is distinct. Whereas a positive CGT is related to a widespread increase of rainfall in SAM, a positive SNAO is related to a precipitation dipole with its positive phase over Pakistan and the negative phase over northern India. The physical mechanisms for the influence of CGT and SNAO on SAM are related to the upper-level geopotential anomaly which affects the amplitude and position of the low-level convergence. The small displacements of the centers of these responses and the low level cold advection from the north east of SA in case of SNAO explain the differences in the corresponding SAM rainfall distributions. These findings are confirmed with the relatively high-resolution coupled climate model EC-Earth, which gives confidence in the physical basis and robustness of these extratropical variability modes and their influence on the South-Asian monsoon rainfall.

  5. Likely seeding of cirrus clouds by stratospheric Kasatochi volcanic aerosol particles near a mid-latitude tropopause fold

    Science.gov (United States)

    Campbell, James R.; Welton, Ellsworth J.; Krotkov, Nickolay A.; Yang, Kai; Stewart, Sebastian A.; Fromm, Michael D.

    2012-01-01

    Following the explosive 7-8 August 2008 Mt. Kasatochi volcanic eruption in southwestern Alaska, a segment of the dispersing stratospheric aerosol layer was profiled beginning 16 August in continuous ground-based lidar measurements over the Mid-Atlantic coast of the eastern United States. On 17-18 August, the layer was displaced downward into the upper troposphere through turbulent mixing near a tropopause fold. Cirrus clouds and ice crystal fallstreaks were subsequently observed, having formed within the entrained layer. The likely seeding of these clouds by Kasatochi aerosol particles is discussed. Cloud formation is hypothesized as resulting from either preferential homogenous freezing of relatively large sulfate-based solution droplets deliquesced after mixing into the moist upper troposphere or through heterogeneous droplet activation by volcanic ash. Satellite-borne spectrometer measurements illustrate the evolution of elevated Kasatochi SO 2 mass concentrations regionally and the spatial extent of the cirrus cloud band induced by likely particle seeding. Satellite-borne polarization lidar observations confirm ice crystal presence within the clouds. Geostationary satellite-based water vapor channel imagery depicts strong regional subsidence, symptomatic of tropopause folding, along a deepening trough in the sub-tropical westerlies. Regional radiosonde profiling confirms both the position of the fold and depth of upper-tropospheric subsidence. These data represent the first unambiguous observations of likely cloud seeding by stratospheric volcanic aerosol particles after mixing back into the upper troposphere.

  6. The Impact of ENSO on Extratropical Low Frequency Noise in Seasonal Forecasts

    Science.gov (United States)

    Schubert, Siegfried D.; Suarez, Max J.; Chang, Yehui; Branstator, Grant

    2000-01-01

    This study examines the uncertainty in forecasts of the January-February-March (JFM) mean extratropical circulation, and how that uncertainty is modulated by the El Nino/Southern Oscillation (ENSO). The analysis is based on ensembles of hindcasts made with an Atmospheric General Circulation Model (AGCM) forced with sea surface temperatures observed during; the 1983 El Nino and 1989 La Nina events. The AGCM produces pronounced interannual differences in the magnitude of the extratropical seasonal mean noise (intra-ensemble variability). The North Pacific, in particular, shows extensive regions where the 1989 seasonal mean noise kinetic energy (SKE), which is dominated by a "PNA-like" spatial structure, is more than twice that of the 1983 forecasts. The larger SKE in 1989 is associated with a larger than normal barotropic conversion of kinetic energy from the mean Pacific jet to the seasonal mean noise. The generation of SKE due to sub-monthly transients also shows substantial interannual differences, though these are much smaller than the differences in the mean flow conversions. An analysis of the Generation of monthly mean noise kinetic energy (NIKE) and its variability suggests that the seasonal mean noise is predominantly a statistical residue of variability resulting from dynamical processes operating on monthly and shorter times scales. A stochastically-forced barotropic model (linearized about the AGCM's 1983 and 1989 base states) is used to further assess the role of the basic state, submonthly transients, and tropical forcing, in modulating the uncertainties in the seasonal AGCM forecasts. When forced globally with spatially-white noise, the linear model generates much larger variance for the 1989 base state, consistent with the AGCM results. The extratropical variability for the 1989 base state is dominanted by a single eigenmode, and is strongly coupled with forcing over tropical western Pacific and the Indian Ocean, again consistent with the AGCM results

  7. Stellar refraction - A tool to monitor the height of the tropopause from space

    Science.gov (United States)

    Schuerman, D. W.; Giovane, F.; Greenberg, J. M.

    1975-01-01

    Calculations of stellar refraction for a setting or rising star as viewed from a spacecraft show that the tropopause is a discernible feature in a plot of refraction vs time. The height of the tropopause is easily obtained from such a plot. Since the refraction suffered by the starlight appears to be measurable with some precision from orbital altitudes, this technique is suggested as a method for remotely monitoring the height of the tropopause. Although limited to nighttime measurements, the method is independent of supporting data or model fitting and easily lends itself to on-line data reduction.

  8. Interactions between clouds and atmospheric circulation in the extratropics

    Science.gov (United States)

    Ceppi, Paulo

    In climate models, the simulation of clouds is known to be particularly problematic, leading to important biases in the climatological energy balance on regional scales, as well as to large uncertainties in the future amount of warming in response to greenhouse gas increase. This thesis explores the connections between clouds and atmospheric circulation in extratropical regions. In particular, we investigate the impacts of clouds and their uncertainties on atmospheric circulation and its response to global warming. We find that clouds have very substantial effects both on the mean circulation and on its future response to warming in climate models. In the mean state, the position of the midlatitude jet correlates well with the midlatitude shortwave cloud-radiative effect (SW CRE), which suffers from very large biases in models. Models in which midlatitude SW CRE is too negative have anomalously cold midlatitudes, leading to an anomalously equatorward jet position. This result is supported by idealized model experiments and appears consistent with the effect of midlatitude baroclinicity changes on eddy activity. This means that an accurate representation of clouds and their radiative effects is essential to correctly portray the mean circulation. In the context of greenhouse gas--forced change, we demonstrate that cloud-radiative changes have a surprisingly large impact on the atmospheric circulation response. This results mainly from the SW cloud feedback, whose specific spatial structure induces low-latitude warming and high-latitude cooling, enhancing midlatitude baroclinicity and favoring a strengthening and poleward shift of the midlatitude jet. This opposes the effects of other major feedbacks (e.g., the water vapor feedback and the longwave cloud feedback), which produce polar-amplified warming and weakened midlatitude baroclinicity. For this reason, cloud-radiative changes explain the majority of the poleward expansion of atmospheric circulation in our model

  9. The diagnosis of a preblocking explosively-developing extratropical cyclone system

    Science.gov (United States)

    Uhl, Mary A.; Smith, Phillip J.; Lupo, Anthony R.; Zwack, Peter

    1992-01-01

    This paper presents the diagnosis of an extratropical cyclone that developed explosively from 18 to 19 January 1979 over the North Atlantic Ocean. The diagnosis applies data obtained from the Goddard Laboratory for Atmospheres FGGE SOP-1 level III-b global analyses on a 4 deg latitude by 5 deg longitude grid to the extended height tendency and the Zwack-Okossi development equations. The cyclone developed initially in response to cyclonic vorticity advection downstream from an upper air through, warm air advection in a strongly baroclinic region, and latent heat release in the cyclone domain. As development continued, thermal advection and latent heat release increased their role in forcing height falls in the cyclone domain, while the influence of vorticity advection decreased. Finally, development ceased when anticyclonic vorticity advection below 700 mb and adiabatic cooling in the ascending air combined to neutralize the influence of warm air advection and latent heat release.

  10. Mesoscale generation of available potential energy in the warm sector of an extratropical cyclone

    Science.gov (United States)

    Fuelberg, H. E.; Ruminski, M. G.; Starr, D. OC.

    1985-01-01

    The generation of available potential energy (APE) was evaluated in the warm sector of an extratropical cyclone containing intense convective activity. Mesoscale rawinsonde data from AVE-SESAME '79 was employed. Parametrization techniques were used for latent and sensible heating components, and variations for the Kuo scheme provided convective latent heat release. Radiative transfer models were used to obtain estimates of infrared and solar processes. The results indicated that solar heating was greater than IR cooling near midday. An extensive low-level cloud deck was the most radiatively active area. Negative generation of APE occurred during most of the period for the SESAME domain as a whole. The leading contributor was convective latent heating located primarily in regions of negative efficiency. Infrared cooling was the only component to consistently produce positive generation. Sensible heating provided an important sink of APE in the low levels during the afternoon.

  11. Effects of Extratropical Cyclone Frequency and Intensity on mass balance of the Greenland Ice Sheet

    Science.gov (United States)

    Auger, J.; Birkel, S. D.; Maasch, K. A.; Mayewski, P. A.

    2014-12-01

    Significant Arctic-wide warming over the past decade is thought to result in part from a weakening of the equator-pole thermal gradient in the atmosphere. Francis and Vavrus (2012) and others link Arctic amplification, or enhanced Arctic warming, to decreasing extratropical cyclone (ETC) speeds, and increasing northward meridional heat transports. Here, we are using the latest high-resolution reanalysis models (ASR, JRA-55, CFSR, ERA-Interim, MERRA) to evaluate how Arctic amplification may be impacting the mass balance of the Greenland Ice Sheet. Our approach is to assess synoptic-scale changes in circulation as represented by changes in storm tracks and storm intensities in the North Atlantic region. As part of this work, we are validating the reanalysis models against existing accumulation, ablation, and meteorological station data available across Greenland, and therefore hope to gain insights on model performance and applicability to the problem domain.

  12. High resolution VHF radar measurements of tropopause structure and variability at Davis, Antarctica (69° S, 78° E

    Directory of Open Access Journals (Sweden)

    S. P. Alexander

    2013-03-01

    Full Text Available Two years of Very High Frequency (VHF radar echo power observations are used to examine the structure and variability of the tropopause at Davis, Antarctica. Co-located radiosonde and ozonesonde launches provide data with which to calculate the lapse-rate and chemical tropopauses. The radar tropopause, defined as the maximum vertical gradient of echo return power, can be used as a definition of the Antarctic tropopause throughout the year under all meteorological conditions. During the extended summer period of December–April (DJFMA inclusive, radar tropopauses are (0.2 ± 0.4 km lower than radiosonde lapse-rate (i.e. the World Meteorological Organisation – WMO tropopauses and during the extended winter period of June–October (JJASO inclusive, the radar tropopauses are (0.8 ± 1.0 km lower. A potential vorticity tropopause is defined as the altitude of the −2 PVU surface (where 1 PVU = 106 m2 s−1 K kg−1. This is (0.3 ± 0.5 km lower than the radar tropopause during DJFMA and (0.5 ± 1.0 km lower during JJASO. The radar, potential vorticity and ozone tropopauses decrease in altitude during increasingly strong cyclonic conditions, in contrast to the radiosonde WMO tropopause which remains nearly constant. During strong JJASO cyclonic conditions, there are large (several km differences between WMO tropopause altitudes and radar tropopause altitudes. A seasonal cycle in tropopause fold occurrence is observed, with approximately a three-fold increase during JJASO.

  13. Accelerating two-stage explosive development of an extratropical cyclone over the northwestern Pacific Ocean: a piecewise potential vorticity diagnosis

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    Shenming Fu

    2014-03-01

    Full Text Available An extreme explosive extratropical cyclone over the northwestern Pacific Ocean (NPO that formed in winter 2004 and went through two distinct rapid deepening periods was successfully simulated by a non-hydrostatic mesoscale model (MM5. Based on the simulation, the cyclone's rapid deepening was investigated in detail using the piecewise potential vorticity (PV inversion method which successfully captured the characteristics of the cyclone and its associated background circulations. Results indicated that explosive development of the cyclone was dominated by forcings in the extended surface layer (ESL, which were closely related to baroclinity (temperature advection and boundary layer processes (sensible heat exchange. In the interior layer (IL, direct effects of condensation were mainly conducive to the cyclone's development, whereas indirect effects (interactions with other layers mainly acted conversely. Processes associated with latent heat release (LHR were characterised by nonlinearity. Features of the precipitation, including intensity, duration, range and relative configuration to the cyclone determined the influences of condensation on the cyclone. In the upper layer (UL, tropopause-folding processes and horizontal PV advection were main influencing factors to the evolution of the cyclone. Upper-level forcings firstly exerted slight effects on the cyclone's development, since upper-level positive PV anomalies were far from the cyclone; then, as the influencing short-wave trough and the cyclone both moved northeastward, upper-level positive PV anomalies merged, enhanced and entered key areas of the cyclone, and thus both direct and indirect effects associated with the upper-level forcings strengthened significantly around the cyclone, and this dominated the cyclone's transition from a moderate explosive cyclone to an extreme one.

  14. A-Train Based Observational Metrics for Model Evaluation in Extratropical Cyclones

    Science.gov (United States)

    Naud, Catherine M.; Booth, James F.; Del Genio, Anthony D.; van den Heever, Susan C.; Posselt, Derek J.

    2015-01-01

    Extratropical cyclones contribute most of the precipitation in the midlatitudes, i.e. up to 70 during winter in the northern hemisphere, and can generate flooding, extreme winds, blizzards and have large socio-economic impacts. As such, it is important that general circulation models (GCMs) accurately represent these systems so their evolution in a warming climate can be understood. However, there are still uncertainties on whether warming will increase their frequency of occurrence, their intensity and how much rain or snow they bring. Part of the issue is that models have trouble representing their strength, but models also have biases in the amount of clouds and precipitation they produce. This is caused by potential issues in various aspects of the models: convection, boundary layer, and cloud scheme to only mention a few. In order to pinpoint which aspects of the models need improvement for a better representation of extratropical cyclone precipitation and cloudiness, we will present A-train based observational metrics: cyclone-centered, warm and cold frontal composites of cloud amount and type, precipitation rate and frequency of occurrence. Using the same method to extract similar fields from the model, we will present an evaluation of the GISS-ModelE2 and the IPSL-LMDZ-5B models, based on their AR5 and more recent versions. The AR5 version of the GISS model underestimates cloud cover in extratropical cyclones while the IPSL AR5 version overestimates it. In addition, we will show how the observed CloudSat-CALIPSO cloud vertical distribution across cold fronts changes with moisture amount and cyclone strength, and test if the two models successfully represent these changes. We will also show how CloudSat-CALIPSO derived cloud type (i.e. convective vs. stratiform) evolves across warm fronts as cyclones age, and again how this is represented in the models. Our third process-based analysis concerns cumulus clouds in the post-cold frontal region and how their

  15. Observational Diagnoses of Extratropical Ozone STE During the Aura Era

    Science.gov (United States)

    Olsen, Mark A.; Douglass, Anne R.; Witte, Jacquie C.; Kaplan, Trevor B.

    2011-01-01

    The transport of ozone from the stratosphere to the extratropical troposphere is an important boundary condition to tropospheric chemistry. However, previous direct estimates from models and indirect estimates from observations have poorly constrained the magnitude of ozone stratosphere-troposphere exchange (STE). In this study we provide a direct diagnosis of the extratropical ozone STE using data from the Microwave Limb Sounder on Aura and output of the MERRA reanalysis over the time period from 2005 to the present. We find that the mean annual STE is about 275 Tg/yr and 205 Tg/yr in the NH and SH, respectively. The interannual variability of the magnitude is about twice as great in the NH than the SH. We find that this variability is dominated by the seasonal variability during the late winter and spring. A comparison of the ozone flux to the mass flux reveals that there is not a simple relationship between the two quantities. This presentation will also examine the magnitude and distribution of ozone in the lower stratosphere relative to the years of maximum and minimum ozone STE. Finally, we will examine any possible signature of increased ozone STE in the troposphere using sonde and tropospheric ozone residual (TOR) data, and output from the Global Modeling Initiative Chemistry Transport Model (GMI CTM).

  16. Formation of large (≃100 μm ice crystals near the tropical tropopause

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    D. S. Sayres

    2007-05-01

    Full Text Available Recent high-altitude aircraft measurements with in situ imaging instruments indicated the presence of relatively large (≃100 μm length, thin (aspect ratios of ≃6:1 or larger hexagonal plate ice crystals near the tropical tropopause in very low concentrations (<0.01 L−1. These crystals were not produced by deep convection or aggregation. We use simple growth-sedimentation calculations as well as detailed cloud simulations to evaluate the conditions required to grow the large crystals. Uncertainties in crystal aspect ratio leave a range of possibilities, which could be constrained by knowledge of the water vapor concentration in the air where the crystal growth occurred. Unfortunately, water vapor measurements made in the cloud formation region near the tropopause ranged from <2 ppmv to ≃3.5 ppmv. The higher water vapor concentrations correspond to very large ice supersaturations (relative humidities with respect to ice of about 200%. If the aspect ratios of the hexagonal plate crystals are as small as the image analysis suggests (6:1, see companion paper Lawson et al., 2007 then growth of the large crystals before they sediment out of the supersaturated layer would only be possible if the water vapor concentration were on the high end of the range indicated by the different measurements (>3 ppmv. On the other hand, if the crystal aspect ratios are quite a bit larger (≃14, then H2O concentrations toward the low of the measurement range (≃2–2.3 ppmv would suffice to grow the large crystals. Gravity-wave driven temperature and vertical wind perturbations only slightly modify the H2O concentrations needed to grow the crystals. We find that it would not be possible to grow the large crystals with water concentrations less than 2 ppmv, even with assumptions of a very high aspect ratio of 15 and steady upward motion of 2 cm s−1 to loft the crystals in the tropopause region. These calculations would seem to imply that the measurements

  17. Formation of large (≃100 μm ice crystals near the tropical tropopause

    Directory of Open Access Journals (Sweden)

    M. J. Alexander

    2008-03-01

    Full Text Available Recent high-altitude aircraft measurements with in situ imaging instruments indicated the presence of relatively large (≃100 μm length, thin (aspect ratios of ≃6:1 or larger hexagonal plate ice crystals near the tropical tropopause in very low concentrations (<0.01 L−1. These crystals were not produced by deep convection or aggregation. We use simple growth-sedimentation calculations as well as detailed cloud simulations to evaluate the conditions required to grow the large crystals. Uncertainties in crystal aspect ratio leave a range of possibilities, which could be constrained by knowledge of the water vapor concentration in the air where the crystal growth occurred. Unfortunately, water vapor measurements made in the cloud formation region near the tropopause with different instruments ranged from <2 ppmv to ≃3.5 ppmv. The higher water vapor concentrations correspond to very large ice supersaturations (relative humidities with respect to ice of about 200%. If the aspect ratios of the hexagonal plate crystals are as small as the image analysis suggests (6:1, see companion paper (Lawson et al., 2008 then growth of the large crystals before they sediment out of the supersaturated layer would only be possible if the water vapor concentration were on the high end of the range indicated by the different measurements (>3 ppmv. On the other hand, if the crystal aspect ratios are quite a bit larger (≃10:1, then H2O concentrations toward the low end of the measurement range (≃2–2.5 ppmv would suffice to grow the large crystals. Gravity-wave driven temperature and vertical wind perturbations only slightly modify the H2O concentrations needed to grow the crystals. We find that it would not be possible to grow the large crystals with water concentrations less than 2 ppmv, even with assumptions of a very high aspect ratio of 15 and steady upward motion of 2 cm s−1 to loft the crystals in the tropopause region. These calculations would seem

  18. On the Effect of Extratropical Wind Stress Forcing on Pacific Subtropical Cells and Tropical Climate

    Science.gov (United States)

    Graffino, Giorgio; Farneti, Riccardo; Kucharski, Fred

    2017-04-01

    The influence of extratropical atmospheric dynamics on the tropical ocean state is a classical example of ocean-atmosphere teleconnection. One way to influence tropical climate is through oceanic SubTropical Cells (STCs), shallow overturning circulation structures connecting the Equatorial Ocean with the subtropical regions. STC are responsible for large mass and energy transports, and their influence on tropical climate, and consequently on the global climate, is fundamental both on the mean and its variability. These circulation structures are present in all basins across the Tropics (Pacific, Atlantic, and Indian Ocean), with different properties and strengths due to the features of each basin. We focus here on the effect of off-equatorial winds on the Pacific STCs, which are the largest and have been previously studied for their potential role in driving low-frequency Pacific variability. Using the Modular Ocean Model version 5 (MOM5), we force the ocean surface with idealized wind stress and wind stress curl anomaly patterns, in order to highlight the influence of subtropical and extratropical forcing on STCs dynamics, and, eventually, on some aspects of Pacific tropical climate. Results have been compared with a control simulation, in which a climatological forcing has been applied at the ocean surface. Our simulations show an increased (reduced) meridional water transport for positive (negative) wind stress anomalies in the Subtropics; the structure of the thermocline at the Equator is modified as well, where cold (warm) anomalies appear. Those signatures result from anomalous values of Equatorial UnderCurrent (EUC), which is partly fed by the STCs. Meridional ocean heat transport is influenced too, showing larger (weaker) values for stronger (weaker) subtropical wind stress. Anomalous circulations are further analyzed for the interior and western boundary transports, and scalings are derived linking subtropical wind stress, STC transports and tropical

  19. Impact of deep convection in the tropical tropopause layer in West Africa: in-situ observations and mesoscale modelling

    Directory of Open Access Journals (Sweden)

    F. Fierli

    2010-02-01

    Full Text Available We present the analysis of the impact of convection on the composition of the tropical tropopause layer region (TTL in West-Africa during the AMMA-SCOUT campaign. Geophysica M55 aircraft observations of water vapor, ozone, aerosol and CO2 show perturbed values at altitudes ranging from 14 km to 17 km (above the main convective outflow and satellite data indicates that air detrainment is likely originated from convective cloud east of the flight. Simulations of the BOLAM mesoscale model, nudged with infrared radiance temperatures, are used to estimate the convective impact in the upper troposphere and to assess the fraction of air processed by convection. The analysis shows that BOLAM correctly reproduces the location and the vertical structure of convective outflow. Model-aided analysis indicates that in the outflow of a large convective system, deep convection can largely modify chemical composition and aerosol distribution up to the tropical tropopause. Model analysis also shows that, on average, deep convection occurring in the entire Sahelian transect (up to 2000 km E of the measurement area has a non negligible role in determining TTL composition.

  20. Weak simulated extratropical responses to complete tropical deforestation

    Science.gov (United States)

    Findell, K.L.; Knutson, T.R.; Milly, P.C.D.

    2006-01-01

    The Geophysical Fluid Dynamics Laboratory atmosphere-land model version 2 (AM2/LM2) coupled to a 50-m-thick slab ocean model has been used to investigate remote responses to tropical deforestation. Magnitudes and significance of differences between a control run and a deforested run are assessed through comparisons of 50-yr time series, accounting for autocorrelation and field significance. Complete conversion of the broadleaf evergreen forests of South America, central Africa, and the islands of Oceania to grasslands leads to highly significant local responses. In addition, a broad but mild warming is seen throughout the tropical troposphere (deforested run and the control run are similar in magnitude and area to the differences between nonoverlapping segments of the control run. These simulations suggest that extratropical responses to complete tropical deforestation are unlikely to be distinguishable from natural climate variability.

  1. Multiple Satellite Observations of Cloud Cover in Extratropical Cyclones

    Science.gov (United States)

    Naud, Catherine M.; Booth, James F.; Posselt, Derek J.; van den Heever, Susan C.

    2013-01-01

    Using cloud observations from NASA Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, and CloudSat-CALIPSO, composites of cloud fraction in southern and northern hemisphere extratropical cyclones are obtained for cold and warm seasons between 2006 and 2010, to assess differences between these three data sets, and between summer and winter cyclones. In both hemispheres and seasons, over the open ocean, the cyclone-centered cloud fraction composites agree within 5% across the three data sets, but behind the cold fronts, or over sea ice and land, the differences are much larger. To supplement the data set comparison and learn more about the cyclones, we also examine the differences in cloud fraction between cold and warm season for each data set. The difference in cloud fraction between cold and warm season southern hemisphere cyclones is small for all three data sets, but of the same order of magnitude as the differences between the data sets. The cold-warm season contrast in northern hemisphere cyclone cloud fractions is similar for all three data sets: in the warm sector, the cold season cloud fractions are lower close to the low, but larger on the equator edge than their warm season counterparts. This seasonal contrast in cloud fraction within the cyclones warm sector seems to be related to the seasonal differences in moisture flux within the cyclones. Our analysis suggests that the three different data sets can all be used confidently when studying the warm sector and warm frontal zone of extratropical cyclones but caution should be exerted when studying clouds in the cold sector.

  2. A Multivariate Analysis of Extratropical Cyclone Environmental Sensitivity

    Science.gov (United States)

    Tierney, G.; Posselt, D. J.; Booth, J. F.

    2015-12-01

    The implications of a changing climate system include more than a simple temperature increase. A changing climate also modifies atmospheric conditions responsible for shaping the genesis and evolution of atmospheric circulations. In the mid-latitudes, the effects of climate change on extratropical cyclones (ETCs) can be expressed through changes in bulk temperature, horizontal and vertical temperature gradients (leading to changes in mean state winds) as well as atmospheric moisture content. Understanding how these changes impact ETC evolution and dynamics will help to inform climate mitigation and adaptation strategies, and allow for better informed weather emergency planning. However, our understanding is complicated by the complex interplay between a variety of environmental influences, and their potentially opposing effects on extratropical cyclone strength. Attempting to untangle competing influences from a theoretical or observational standpoint is complicated by nonlinear responses to environmental perturbations and a lack of data. As such, numerical models can serve as a useful tool for examining this complex issue. We present results from an analysis framework that combines the computational power of idealized modeling with the statistical robustness of multivariate sensitivity analysis. We first establish control variables, such as baroclinicity, bulk temperature, and moisture content, and specify a range of values that simulate possible changes in a future climate. The Weather Research and Forecasting (WRF) model serves as the link between changes in climate state and ETC relevant outcomes. A diverse set of output metrics (e.g., sea level pressure, average precipitation rates, eddy kinetic energy, and latent heat release) facilitates examination of storm dynamics, thermodynamic properties, and hydrologic cycles. Exploration of the multivariate sensitivity of ETCs to changes in control parameters space is performed via an ensemble of WRF runs coupled with

  3. Some aspects of temporal structure of leading winter extratropical modes

    Science.gov (United States)

    Pastor, M. A.; Doblas-Reyes, F. J.; Casado, M. J.

    2003-04-01

    SOME ASPECTS OF TEMPORAL STRUCTURE OF LEADING WINTER EXTRATROPICAL MODES M.A.Pastor (1), F. J. Doblas-Reyes (2), M. J. Casado (1) (1) I Instituto Nacional de Meteorología, c/Leonardo Prieto Castro,8,28071 ,Madrid,Spain, a.pastor@inm.es (2) ECMWF, Shinfield Park,RG2 9AX, Reading, UK, f.doblas-reyes@ecmwf.int As a first step in the evaluation of the capability of seasonal ensemble predictions to reproduce the leading modes which dominate the extratropical northern circulation and to explore the ensemble predictability, we examine the power spectra and timescale properties of the dominant atmospheric teleconnection patterns like the North Atlantic Oscillation (NAO), the Pacific-North America (PNA) patterns, etc. using the National Centres for Environmental Prediction (NCEP) re-analyses spanning the winters of 1948-2000 over the Northern Hemisphere poleward of 20ºN. The teleconnection patterns are identified by applying a rotated principal component analysis (RPCA) to the daily unfiltered 500-hPa geopotential height field. The election of the RPCA methodology is motivated by the fact that identifies simple and unique patterns of spatial dataset variability. The temporal evolution of the selected patterns can be understood as a stochastic processes with an e-folding timescale less than 10 days. The shortness of this timescale indicates that the excitation of these teleconnection patterns is limited to a period of time limited to a few days. Then, this study shows that the selected patterns evolve on timescales less than 2 weeks in agreement with very recent published works. It is emphasized the use of daily data in order to improve our understanding of the growth and decay mechanisms of teleconnection patterns, since using monthly or seasonal data, can produce a misleading picture of the underlying dynamics of the anomalies with time scales much shorter than 2 months.

  4. The impact of extratropical warming on the tropical precipitation

    Science.gov (United States)

    Yoshimori, Masakazu; Abe-Ouchi, Ayako; Tatebe, Hiroaki; Nozawa, Toru

    2017-04-01

    From paleoclimate evidence to future climate projections, it has been reported that the asymmetric warming (or cooling) between the northern and southern hemisphere extratropics induces the meridional shift in the tropical precipitation. Such a shift is often understood by the energy-flux framework in that the extra energy is transported from more warming to less warming hemispheres through the change in the Hadley circulation. As the Hadley circulation transports energy in opposite direction to the moisture, the tropical precipitation tends to be intensified in the hemisphere of a larger warming. This framework is shown to be particularly useful for modelling results without ocean dynamical feedback. In the current study, a fully coupled atmosphere-ocean model is used to investigate the impact of extratropical warming on the tropical precipitation under the realistic RCP4.5 scenario. It is shown that the mid-high latitude warming alone in the poleward of 40° (56% global warming) can significantly affect the tropical precipitation change in the equatorward of 20° (38% hemispheric contrast) from late autumn to early winter. High-latitude warming alone affects much less. This meridional change in the tropical precipitation is largely explained by the circulation change, rather than the humidity change. The reduced northward eddy momentum and heat fluxes in the northern hemisphere induces anomalous Hadley circulation in the northern tropics. This change seems to weaken the equatorial upwelling in the Pacific, which leads to the equatorial SST rise. The equatorial sea surface warming induces the meridionally symmetric pattern of the anomalous Hadley circulation (though, asymmetric in strength), resulting in the northward migration of the tropical precipitation. The larger change in the ocean heat transport near the equator, relative to the atmosphere, requires a more refined theory than the conventional energy-flux framework.

  5. Large-Scale Weather Disturbances in Mars’ Southern Extratropics

    Science.gov (United States)

    Hollingsworth, Jeffery L.; Kahre, Melinda A.

    2015-11-01

    Between late autumn and early spring, Mars’ middle and high latitudes within its atmosphere support strong mean thermal gradients between the tropics and poles. Observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). These extratropical weather disturbances are key components of the global circulation. Such wave-like disturbances act as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively lifted and radiatively active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are examined. Simulations that adapt Mars’ full topography compared to simulations that utilize synthetic topographies emulating key large-scale features of the southern middle latitudes indicate that Mars’ transient barotropic/baroclinic eddies are highly influenced by the great impact basins of this hemisphere (e.g., Argyre and Hellas). The occurrence of a southern storm zone in late winter and early spring appears to be anchored to the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre

  6. Convective formation of pileus cloud near the tropopause

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    T. J. Garrett

    2006-01-01

    Full Text Available Pileus clouds form where humid, vertically stratified air is mechanically displaced ahead of rising convection. This paper describes convective formation of pileus cloud in the tropopause transition layer (TTL, and explores a possible link to the formation of long-lasting cirrus at cold temperatures. The study examines in detail in-situ measurements from off the coast of Honduras during the July 2002 CRYSTAL-FACE experiment that showed an example of TTL cirrus associated with, and penetrated by, deep convection. The TTL cirrus was enriched with total water compared to its surroundings, but was composed of extremely small ice crystals with effective radii between 2 and 4 μm. Through gravity wave analysis, and intercomparison of measured and simulated cloud microphysics, it is argued that the TTL cirrus originated neither from convectively-forced gravity wave motions nor environmental mixing alone. Rather, it is hypothesized that a combination of these two processes was involved in which, first, a pulse of convection forced pileus cloud to form from TTL air; second, the pileus layer was punctured by the convective pulse and received larger ice crystals through interfacial mixing; third, the addition of this condensate inhibited evaporation of the original pileus ice crystals where a convectively forced gravity wave entered its warm phase; fourth, through successive pulses of convection, a sheet of TTL cirrus formed. While the general incidence and longevity of pileus cloud remains unknown, in-situ measurements, and satellite-based Microwave Limb Sounder retrievals, suggest that much of the tropical TTL is sufficiently humid to be susceptible to its formation. Where these clouds form and persist, there is potential for an irreversible repartition from water vapor to ice at cold temperatures.

  7. The relationship between clouds and dynamics in Southern Hemisphere extratropical cyclones in the real world and a climate model

    Science.gov (United States)

    Govekar, Pallavi D.; Jakob, Christian; Catto, Jennifer

    2014-06-01

    The representation of clouds over the Southern Ocean in contemporary climate models remains a major challenge. A major dynamical influence on the structure of clouds is the passage of extratropical cyclones. They exert significant dynamical influences on the clouds in the dynamically active frontal regions as well as in the dynamically suppressed regions ahead and behind the cyclones. A cyclone compositing methodology is applied to a reanalysis and vertical profiles of cloudiness from CloudSat/CALIPSO to quantify the relationship between clouds and dynamics in extratropical cyclones over the Southern Ocean. It is found that the range of cloud fraction, vertical motion, and relative humidity changes considerably with height. There is a strong quasi-linear relationship between the three variables which changes with altitude. After establishing the observed relationships, the methodology is applied to the Australian Community Climate and Earth System Simulator to evaluate the model's ability to simulate the identified cloud-dynamics relationships. While the model is able to qualitatively reproduce the overall cloud structure, the circulation around the cyclone is generally too weak. As a result, the model fails to represent the observed cloud to dynamics relationship. This wrong relationship in the model leads to a misrepresentation of the cloud field manifested as either an error in the cloud fraction or as simulating the "right" clouds for the "wrong" reason. The result underscores the importance of relationship-oriented model evaluation techniques over simple right or wrong assessments.

  8. Midlatitude Cirrus Clouds and Multiple Tropopauses from a 2002-2006 Climatology over the SIRTA Observatory

    CERN Document Server

    Noel, Vincent

    2007-01-01

    This study present a comparison of lidar observations of midlatitude cirrus clouds over the SIRTA observatory between 2002 and 2006 with multiple tropopauses (MT) retrieved from radiosounding temperature profiles. The temporal variability of MT properties (frequency, thickness) are discussed. Results show a marked annual cycle, with MT frequency reaching its lowest point in May (~18% occurrence of MT) and slowly rising to more than 40% in DJF. The average thickness of the MT also follows an annual cycle, going from less than 1 km in spring to 1.5 km in late autumn. Comparison with lidar observations show that cirrus clouds show a preference for being located close below the 1st tropopause. When the cloud top is above the 1st tropopause (7% of observations), in 20% of cases the cloud base is above it as well, resulting in a cirrus cloud "sandwiched" between the two tropopauses. Compared to the general distribution of cirrus, cross-tropopause cirrus show a higher frequency of large optical depths, while inter-t...

  9. The CO2 tracer clock for the Tropical Tropopause Layer

    Directory of Open Access Journals (Sweden)

    R.-S. Gao

    2007-07-01

    Full Text Available Observations of CO2 were made in the upper troposphere and lower stratosphere in the deep tropics in order to determine the patterns of large-scale vertical transport and age of air in the Tropical Tropopause Layer (TTL. Flights aboard the NASA WB-57F aircraft over Central America and adjacent ocean areas took place in January and February, 2004 (Pre-AURA Validation Experiment, Pre-AVE and 2006 (Costa Rice AVE, CR-AVE, and for the same flight dates of 2006, aboard the Proteus aircraft from the surface to 15 km over Darwin, Australia (Tropical Warm Pool International Cloud Experiment, TWP-ICE. The data demonstrate that the TTL is composed of two layers with distinctive features: (1 the lower TTL, 350–360 K (potential temperature(θ; approximately 12–14 km, is subject to inputs of convective outflows, as indicated by layers of variable CO2 concentrations, with air parcels of zero age distributed throughout the layer; (2 the upper TTL, from θ=~360 K to ~390 K (14–18 km, ascends slowly and ages uniformly, as shown by a linear decline in CO2 mixing ratio tightly correlated with altitude, associated with increasing age. This division is confirmed by ensemble trajectory analysis. The CO2 concentration at the level of 360 K was 380.0(±0.2 ppmv, indistinguishable from surface site values in the Intertropical Convergence Zone (ITCZ for the flight dates. Values declined with altitude to 379.2(±0.2 ppmv at 390 K, implying that air in the upper TTL monotonically ages while ascending. In combination with the winter slope of the CO2 seasonal cycle (+10.8±0.4 ppmv/yr, the vertical gradient of –0.78 (±0.09 ppmv gives a mean age of 26(±3 days for the air at 390 K and a mean ascent rate of 1.5(±0.3 mm s−1. The TTL near 360 K in the Southern Hemisphere over Australia is very close in CO2 composition to the TTL in the Northern Hemisphere over Costa Rica, with strong contrasts emerging at lower altitudes (<360 K. Both Pre-AVE and CR-AVE CO2 observed

  10. The CO2 tracer clock for the Tropical Tropopause Layer

    Directory of Open Access Journals (Sweden)

    R.-S. Gao

    2007-05-01

    Full Text Available Observations of CO2 were made in the upper troposphere and lower stratosphere in the deep tropics in order to determine the patterns of large-scale vertical transport and age of air in the Tropical Tropopause Layer (TTL. Flights aboard the NASA WB-57F aircraft over Central America and adjacent ocean areas took place in January and February, 2004 (Pre-AURA Validation Experiment, Pre-AVE and 2006 (Costa Rice AVE, CR-AVE, and for the same flight dates of 2006, aboard the Proteus aircraft from the surface to 15 km over Darwin, Australia (Tropical Warm Pool International Cloud Experiment , TWP-ICE. The data demonstrate that the TTL is composed of two layers with distinctive features: (1 the lower TTL, 350–360 K (potential temperature (θ; approximately 12–14 km, is subject to inputs of convective outflows, as indicated by layers of variable CO2 concentrations, with air parcels of zero age distributed throughout the layer; (2 the upper TTL, from θ= ~360 K to ~390 K (14–18 km, ascends slowly and ages uniformly, as shown by a linear decline in CO2 mixing ratio tightly correlated with altitude, associated with increasing age. This division is confirmed by ensemble trajectory analysis. The CO2 concentration at the level of 360 K was 380.0(±0.2 ppmv, indistinguishable from surface site values in the Intertropical Convergence Zone (ITCZ for the flight dates. Values declined with altitude to 379.2(±0.2 ppmv at 390 K, implying that air in the upper TTL monotonically ages while ascending. In combination with the winter slope of the CO2 seasonal cycle (+10.8±0.4 ppmv/yr, the vertical gradient of 0.78 (±0.09 ppmv gives a mean age of 26(±3 days for the air at 390 K and a mean ascent rate of 1.5(±0.3 mm s−1. The TTL near 360 K in the Southern Hemisphere over Australia is very close in CO2 composition to the TTL in the Northern Hemisphere over Costa Rica, with strong contrasts emerging at lower altitudes (<360 K. Both Pre-AVE and CR-AVE CO2 observed

  11. Variability and transport of ozone at the tropopause from the first year of GASP data

    Science.gov (United States)

    Nastrom, G. D.

    1977-01-01

    The relationships of ozone near the tropopause with potential vorticity temperature, and distance from the tropopause are examined. Data are also used to estimate the vertical and horizontal fluxes of ozone near the tropopause. The present estimates of the total flux of ozone into the troposphere verify the model results. Although the distribution of flux between mean motions and diffusion is different and thus suggests that models with coarse horizontal resolution must continue to parameterize much vertical transport by diffusion coefficients. Monthly estimates of the horizontal transient eddy flux of ozone are generally smaller than seasonal or yearly results based on ozonesonde data. This is perhaps because the present estimates are made over monthly periods to reduce the influence of correlation between the annual variations in ozone and meridional wind. The available data support the hypothesis that transient eddy fluxes of ozone have large longitudinal variations.

  12. Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: A case study on cyclone Davina (1999

    Directory of Open Access Journals (Sweden)

    F. Cairo

    2007-12-01

    Full Text Available During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame.

    Temperature anomalies in the tropical tropopause layer (TTL, warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone and the perturbed water distribution in the TTL is illustrated and discussed.

  13. Climatology of cross-tropopause mass exchange over the Tibetan Plateau and its surroundings

    Science.gov (United States)

    Tian, Hongying; Tian, Wenshou; Luo, Jiali; Zhang, Jiankai; Zhang, Min

    2017-04-01

    The cross-tropopause mass flux (CTMF) and long-term trends in stratosphere-troposphere exchange (STE) over the Tibetan Plateau(TP) and its surroundings were analyzed using European Centre for Medium-Range Weather Forecasts reanalysis data. The gross CTMF (the sum of upward and downward mass flux) shows an evident wave train structure over the TP, which is mainly related to the horizontal exchange of air masses along the tropopause associated with the sharp meridional gradient in tropopause pressure or vertical discontinuity of the thermal tropopause in winter. The seasonal cycle of the STE over the TP shows that the gross mass flux is downwards in Northern Hemisphere (NH) winter and upwards in NH summer. The gross CTMF over the TP accounts for 2.96% of the global total CTMF arising from STE processes resolved by Wei method. Both the upward and downward CTMF over the TP exhibit statistically significant positive trends in winter during the period 1979-2009. The strong positive trends of STE in winter over the TP are resulted from the combined effects of the rising tropopause height, enhanced westerlies and decreasing plateau winter monsoon. In summer, both the upward and downward CTMF exhibit statistically significant negative trends over the northern TP, while the trend in upward CTMF is positive over the southern TP, in accordance with the increasing intensity of Asian summer monsoon in recent decades. The sensitivity simulations with a climate model confirm that changes in the Asian monsoon can significantly affect the tropopause and the CTMF over the TP.

  14. Tropopause and hygropause variability over the equatorial Indian Ocean during February and March 1999

    Science.gov (United States)

    MacKenzie, A. R.; Schiller, C.; Peter, T.; Adriani, A.; Beuermann, J.; Bujok, O.; Cairo, F.; Corti, T.; Didonfrancesco, G.; Gensch, I.; Kiemle, C.; KräMer, M.; KröGer, C.; Merkulov, S.; Oulanovsky, A.; Ravegnani, F.; Rohs, S.; Rudakov, V.; Salter, P.; Santacesaria, V.; Stefanutti, L.; Yushkov, V.

    2006-09-01

    Measurements of temperature, water vapor, total water, ozone, and cloud properties were made above the western equatorial Indian Ocean in February and March 1999. The cold-point tropopause was at a mean pressure-altitude of 17 km, equivalent to a potential temperature of 380 K, and had a mean temperature of 190 K. Total water mixing ratios at the hygropause varied between 1.4 and 4.1 ppmv. The mean saturation water vapor mixing ratio at the cold point was 3.0 ppmv. This does not accurately represent the mean of the measured total water mixing ratios because the air was unsaturated at the cold point for about 40% of the measurements. As well as unsaturation at the cold point, saturation was observed above the cold point on almost 30% of the profiles. In such profiles the air was saturated with respect to water ice but was free of clouds (i.e., backscatter ratio <2) at potential temperatures more than 5 K above the tropopause and hygropause. Individual profiles show a great deal of variability in the potential temperatures of the cold point and hygropause. We attribute this to short timescale and space-scale perturbations superimposed on the seasonal cycle. There is neither a clear and consistent "setting" of the tropopause and hygropause to the same altitude by dehydration processes nor a clear and consistent separation of tropopause and hygropause by the Brewer-Dobson circulation. Similarly, neither the tropopause nor the hygropause provides a location where conditions consistently approach those implied by a simple "tropopause freeze drying" or "stratospheric fountain" hypothesis.

  15. A global climate model based, Bayesian climate projection for northern extra-tropical land areas

    Science.gov (United States)

    Arzhanov, Maxim M.; Eliseev, Alexey V.; Mokhov, Igor I.

    2012-04-01

    Projections with contemporary global climate models (GCMs) still markedly deviate from each other on magnitude of climate changes, in particular, in middle to subpolar latitudes. In this work, a climate projection based on the ensemble of 18 CMIP3 GCM models forced by SRES A1B scenario is performed for the northern extra-tropical land. To assess the change of soil state, off-line simulations are performed with the Deep Soil Simulator (DSS) developed at the A.M.Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS). This model is forced by output of the above-mentioned GCM simulations. Ensemble mean and ensemble standard deviation for any variable are calculated by using Bayesian averaging which allows to enhance a contribution from more realistic models and diminish that from less realistic models. As a result, uncertainty for soil and permafrost variables become substantially narrower. The Bayesian weights for each model are calculated based on their performance for the present-day surface air temperature (SAT) and permafrost distributions, and for SAT trend during the 20th century. The results, except for intra-ensemble standard deviations, are not very sensitive to particular choice of Bayesian traits. Averaged over the northern extra-tropical land, annual mean surface air temperature in the ensemble increases by 3.1 ± 1.4 K (ensemble mean±intra-ensemble standard deviation) during the 21st century. Precipitation robustly increases in the pan-Arctic and decreases in the Mediterranean/Black Sea region. The models agree on near-surface permafrost degradation during the 21st century. The area underlain by near-surface permafrost decreases from the contemporary value 20 ± 3 mln sq. km to 14 ± 3 mln sq. km in the late 21st century. This leads to risk for geocryological hazard due to soil subsidence. This risk is classified as moderate to high in the southern and western parts of Siberia and Tibet in Eurasia, and in the region from Alaska

  16. How will precipitation change in extratropical cyclones as the planet warms? Insights from a large initial condition climate model ensemble

    Science.gov (United States)

    Yettella, Vineel; Kay, Jennifer E.

    2017-09-01

    The extratropical precipitation response to global warming is investigated within a 30-member initial condition climate model ensemble. As in observations, modeled cyclonic precipitation contributes a large fraction of extratropical precipitation, especially over the ocean and in the winter hemisphere. When compared to present day, the ensemble projects increased cyclone-associated precipitation under twenty-first century business-as-usual greenhouse gas forcing. While the cyclone-associated precipitation response is weaker in the near-future (2016-2035) than in the far-future (2081-2100), both future periods have similar patterns of response. Though cyclone frequency changes are important regionally, most of the increased cyclone-associated precipitation results from increased within-cyclone precipitation. Consistent with this result, cyclone-centric composites show statistically significant precipitation increases in all cyclone sectors. Decomposition into thermodynamic (mean cyclone water vapor path) and dynamic (mean cyclone wind speed) contributions shows that thermodynamics explains 92 and 95% of the near-future and far-future within-cyclone precipitation increases respectively. Surprisingly, the influence of dynamics on future cyclonic precipitation changes is negligible. In addition, the forced response exceeds internal variability in both future time periods. Overall, this work suggests that future cyclonic precipitation changes will result primarily from increased moisture availability in a warmer world, with secondary contributions from changes in cyclone frequency and cyclone dynamics.

  17. How will precipitation change in extratropical cyclones as the planet warms? Insights from a large initial condition climate model ensemble

    Science.gov (United States)

    Yettella, Vineel; Kay, Jennifer E.

    2016-10-01

    The extratropical precipitation response to global warming is investigated within a 30-member initial condition climate model ensemble. As in observations, modeled cyclonic precipitation contributes a large fraction of extratropical precipitation, especially over the ocean and in the winter hemisphere. When compared to present day, the ensemble projects increased cyclone-associated precipitation under twenty-first century business-as-usual greenhouse gas forcing. While the cyclone-associated precipitation response is weaker in the near-future (2016-2035) than in the far-future (2081-2100), both future periods have similar patterns of response. Though cyclone frequency changes are important regionally, most of the increased cyclone-associated precipitation results from increased within-cyclone precipitation. Consistent with this result, cyclone-centric composites show statistically significant precipitation increases in all cyclone sectors. Decomposition into thermodynamic (mean cyclone water vapor path) and dynamic (mean cyclone wind speed) contributions shows that thermodynamics explains 92 and 95% of the near-future and far-future within-cyclone precipitation increases respectively. Surprisingly, the influence of dynamics on future cyclonic precipitation changes is negligible. In addition, the forced response exceeds internal variability in both future time periods. Overall, this work suggests that future cyclonic precipitation changes will result primarily from increased moisture availability in a warmer world, with secondary contributions from changes in cyclone frequency and cyclone dynamics.

  18. Steady-state aerosol distributions in the extra-tropical, lower stratosphere and the processes that maintain them

    Directory of Open Access Journals (Sweden)

    J. C. Wilson

    2008-02-01

    Full Text Available Measurements of aerosol, N2O and OCS made in the Northern Hemisphere below 21 km altitude following the eruption of Pinatubo are presented and analyzed. After September 1999, the oxidation of OCS and the sedimentation of particles in the extra-tropical overworld maintain the aerosol in a steady state. This analysis empirically links precursor gas to aerosol abundance throughout this region. These processes are tracked with age-of-air which offers advantages over tracking as a function of latitude and altitude. In the extra-tropical, lowermost stratosphere, normalized volume distributions appear constant in time after the fall of 1999. Exchange with the troposphere is important in understanding aerosol evolution there. Size distributions of volcanically perturbed aerosol are included to distinguish between volcanic and non-volcanic conditions. This analysis suggests that model failures to correctly predict OCS and aerosol properties below 20 km in the Northern Hemisphere extra tropics result from inadequate descriptions of atmospheric circulation.

  19. Steady-state aerosol distributions in the extra-tropical, lower stratosphere and the processes that maintain them

    Directory of Open Access Journals (Sweden)

    J. C. Wilson

    2008-11-01

    Full Text Available Measurements of aerosol, N2O and OCS made in the Northern Hemisphere below 21 km altitude following the eruption of Pinatubo are presented and analyzed. After September 1999, the oxidation of OCS and sedimentation of particles in the extra-tropical overworld north of 45 N are found to maintain the aerosol in a steady state. This analysis empirically links precursor gas to aerosol abundance throughout this region. These processes are tracked with age-of-air which offers advantages over tracking as a function of latitude and altitude. In the extra-tropical, lowermost stratosphere, normalized volume distributions appear constant in time after the fall of 1999. Exchange with the troposphere is important in understanding aerosol evolution there. Size distributions of volcanically perturbed aerosol are included to distinguish between volcanic and non-volcanic conditions. This analysis suggests that model failures to correctly predict OCS and aerosol properties below 20 km in the Northern Hemisphere extra tropics result from inadequate descriptions of atmospheric circulation.

  20. Understanding the impact of extra-tropical storms from CORDEX projections over the Scandinavian coast

    Science.gov (United States)

    Veldore, Vidyunmala; Luna, Byron Quan

    2017-04-01

    Response of extra-tropical storms to climate change over the Scandinavian coast in high resolution regional climate projection is investigated in the current study. The complex interactions between North Atlantic oscillation, arctic amplification, ocean-atmospheric interactions and changing nature of synoptic waves will affect the generation and extremity of storm types. The nature of these storms is dependent on large-scale systems over this region, and hence higher resolution climate models might be able to represent the structure and intensity of the storms with accuracy. We propose a tracking algorithm for two seasons autumn (September-October-November) and winter season (December-January-February) providing features to detect the frequency and intensity of storm types for a given coast. Our objective is to understand the impact of changing nature of extreme storm types over the Scandinavian coast. Using a spatial assessment, possible impacts due to future storms in RCP8.5 scenario are assessed and hazard levels are represented.

  1. Boundaries of tropical tropopause layer (TTL): A new perspective based on thermal and stability profiles

    Science.gov (United States)

    Sunilkumar, S. V.; Muhsin, M.; Venkat Ratnam, M.; Parameswaran, K.; Krishna Murthy, B. V.; Emmanuel, Maria

    2017-01-01

    The structure of tropical tropopause layer (TTL) is delineated based on static stability criteria. It is defined as the region extending from the level of minimum static stability to the level of maximum static stability. The static stability and dynamic instability steadily increase from the base to the top of the TTL. Radiosonde data from three tropical stations and Constellation Observing System for Meteorology, Ionosphere, and Climate GPS radio occultation (COSMIC) data over the tropics are used for this investigation. This study suggests that in terms of stability, the TTL can further be considered as a composite of three sublayers: a bottom layer (BL), a middle layer (ML), and an upper layer (UL) embedded between the potential temperatures 350-360 K, 360-380 K, and 380-420 K, respectively. While the BL is significantly influenced by frequent convective outflows, the influence of convection declines across the ML. Ozone and water vapor mixing ratios show a discernible change in their gradients across these sublayers. Occurrences of small-scale turbulence and cirrus are maximum in the BL and decrease in the ML and UL. Longitudinally, the BL is broad and the ML and UL are narrow over the deep convective cores. Strength of static stability in the UL (BL) is relatively strong (weak) centered about the equator, with pronounced features over the deep convective regions. These features of static stability centered about the equator in the BL could be attributed to the convective outflows in the troposphere and that in the UL to the dynamic and radiative processes in the upper troposphere and lower stratosphere.

  2. Stratosphere-troposphere exchange in a summertime extratropical low: analysis

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2006-01-01

    Full Text Available Ozone and carbon monoxide measurements sampled during two commercial flights in airstreams of a summertime midlatitude cyclone are analysed with a Lagrangian-based study (backward trajectories and a Reverse Domain Filling technique to gain a comprehensive understanding of transport effects on trace gas distributions. The study demonstrates that summertime cyclones can be associated with deep stratosphere-troposphere transport. A tropopause fold is sampled twice in its life cycle, once in the lower troposphere (O3≃100 ppbv; CO≃90 ppbv in the dry airstream of the cyclone, and again in the upper troposphere (O3≃200 ppbv; CO≃90 ppbv on the northern side of the large scale potential vorticity feature associated with baroclinic development. In agreement with the maritime development of the cyclone, the chemical composition of the anticyclonic portion of the warm conveyor belt outflow (O3≃40 ppbv; CO≃85 ppbv corresponds to the lowest mixing ratios of both ozone and carbon monoxide in the upper tropospheric airborne observations. The uncertain degree of confidence of the Lagrangian-based technique applied to a 100 km segment of upper level airborne observations with high ozone (200 ppbv and relatively low CO (80 ppbv observed northwest of the cyclone prevents identification of the ozone enrichment process of air parcels embedded in the cyclonic part of the upper level outflow of the warm conveyor belt. Different hypotheses of stratosphere-troposphere exchange are discussed.

  3. Stratosphere-troposphere exchange in a summertime extratropical low: analysis

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2005-11-01

    Full Text Available Ozone and carbone monoxide measurements sampled during two commercial flights in airstreams of a summertime midlatitude cyclone are analysed with a lagrangian-based study (backward trajectories and a Reverse Domain Filling technique to gain a comprehensive understanding of transport effects on trace gas distributions. The study demonstrates that summertime cyclones can be associated with deep stratosphere-troposphere transport. A tropopause fold is sampled twice in its life cycle, once in the lower troposphere (O3≃100 ppbv; CO≃90 ppbv in the dry airstream of the cyclone, and again in the upper troposphere (O3≃200 ppbv; CO≃90 ppbv on the northern side of the large scale potential vorticity feature associated with baroclinic development. In agreement to the maritime development of the cyclone, the chemical composition of the anticyclonic part outflow of the warm conveyor belt (O3≃40 ppbv; CO≃85 ppbv corresponds to the lowest mixing ratios of both ozone and carbone monoxide in upper tropospheric airborne observations. The uncertain degree of confidence of the Lagrangian-based technique applied to a 100 km segment of upper level airborne observations with high ozone (200 ppbv and relatively low CO (80 ppbv observed northwest of the cyclone prevents to identify the ozone enrichment process of air parcels embedded in the cyclonic part of the upper level outflow of the warm conveyor belt. Different hypotheses of stratosphere-troposphere exchange are discussed.

  4. Evaluation of near-tropopause ozone distributions in the Global Modeling Initiative combined stratosphere/troposphere model with ozonesonde data

    Directory of Open Access Journals (Sweden)

    D. B. Considine

    2008-01-01

    Full Text Available The NASA Global Modeling Initiative has developed a combined stratosphere/troposphere chemistry and transport model which fully represents the processes governing atmospheric composition near the tropopause. We evaluate model ozone distributions near the tropopause, using two high vertical resolution monthly mean ozone profile climatologies constructed with ozonesonde data, one by averaging on pressure levels and the other relative to the thermal tropopause. Model ozone is high-biased at the SH tropical and NH midlatitude tropopause by ~45% in a 4° latitude × 5° longitude model simulation. Increasing the resolution to 2°×2.5° increases the NH tropopause high bias to ~60%, but decreases the tropical tropopause bias to ~30%, an effect of a better-resolved residual circulation. The tropopause ozone biases appear not to be due to an overly vigorous residual circulation or excessive stratosphere/troposphere exchange, but are more likely due to insufficient vertical resolution or excessive vertical diffusion near the tropopause. In the upper troposphere and lower stratosphere, model/measurement intercomparisons are strongly affected by the averaging technique. NH and tropical mean model lower stratospheric biases are <20%. In the upper troposphere, the 2°×2.5° simulation exhibits mean high biases of ~20% and~35% during April in the tropics and NH midlatitudes, respectively, compared to the pressure-averaged climatology. However, relative-to-tropopause averaging produces upper troposphere high biases of ~30% and 70% in the tropics and NH midlatitudes. This is because relative-to-tropopause averaging better preserves large cross-tropopause O3 gradients, which are seen in the daily sonde data, but not in daily model profiles. The relative annual cycle of ozone near the tropopause is reproduced very well in the model Northern Hemisphere midlatitudes. In the tropics, the model amplitude of the near-tropopause annual cycle is weak

  5. A diagnosis of the explosive development of two extratropical cyclones

    Science.gov (United States)

    Lupo, Anthony R.; Smith, Phillip J.; Zwack, Peter

    1992-01-01

    This paper examines the 24-h explosive development periods of two extratropical cyclones, the first occurring over the Gulf Stream off the coast of New England from 18 to 19 January 1979 and the second occurring over the southeastern United States from 20 to 21 January 1979. The data used in this study are the First GARP (Global Atmospheric Research Program) Global Experiment (FGGE) level IIIb (SOP I) global analyses on a 4 deg latitude x 5 deg longitude grid. The parameter used to diagnose development is the geostrophic relative vorticity tendency calculated using an extended form of the Zwack-Okossi development equation. This development equation is similar to the Petterssen-Sutcliffe development equation, but is shown to be more complete by explicitly coupling surface development with forcing at all levels above the surface. Cyclonic-vorticity advection, warm-air advection, and latent heat release act to develop the two cyclones, while adiabatic cooling in the ascending air opposes development. Further, vertical profiles of the development quantities for these two cases reveal that vorticity and temperature advection maximize in the 200-300-mb layer, while the latent heat release maximum is typically below 500 mb.

  6. Human-induced greening of the northern extratropical land surface

    Science.gov (United States)

    Mao, Jiafu; Ribes, Aurélien; Yan, Binyan; Shi, Xiaoying; Thornton, Peter E.; Séférian, Roland; Ciais, Philippe; Myneni, Ranga B.; Douville, Hervé; Piao, Shilong; Zhu, Zaichun; Dickinson, Robert E.; Dai, Yongjiu; Ricciuto, Daniel M.; Jin, Mingzhou; Hoffman, Forrest M.; Wang, Bin; Huang, Mengtian; Lian, Xu

    2016-10-01

    Significant land greening in the northern extratropical latitudes (NEL) has been documented through satellite observations during the past three decades. This enhanced vegetation growth has broad implications for surface energy, water and carbon budgets, and ecosystem services across multiple scales. Discernible human impacts on the Earth's climate system have been revealed by using statistical frameworks of detection-attribution. These impacts, however, were not previously identified on the NEL greening signal, owing to the lack of long-term observational records, possible bias of satellite data, different algorithms used to calculate vegetation greenness, and the lack of suitable simulations from coupled Earth system models (ESMs). Here we have overcome these challenges to attribute recent changes in NEL vegetation activity. We used two 30-year-long remote-sensing-based leaf area index (LAI) data sets, simulations from 19 coupled ESMs with interactive vegetation, and a formal detection and attribution algorithm. Our findings reveal that the observed greening record is consistent with an assumption of anthropogenic forcings, where greenhouse gases play a dominant role, but is not consistent with simulations that include only natural forcings and internal climate variability. These results provide the first clear evidence of a discernible human fingerprint on physiological vegetation changes other than phenology and range shifts.

  7. Kelvin-Helmholtz waves in extratropical cyclones passing over mountain ranges: KH Waves in Extratropical Cyclones over Mountain Ranges

    Energy Technology Data Exchange (ETDEWEB)

    Medina, Socorro [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences; Houze, Robert A. [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences; Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-02-19

    Kelvin–Helmholtz billows with horizontal scales of 3–4 km have been observed in midlatitude cyclones moving over the Italian Alps and the Oregon Cascades when the atmosphere was mostly statically stable with high amounts of shear and Ri < 0.25. In one case, data from a mobile radar located within a windward facing valley documented a layer in which the shear between down-valley flow below 1.2 km and strong upslope cross-barrier flow above was large. Several episodes of Kelvin–Helmholtz waves were observed within the shear layer. The occurrence of the waves appears to be related to the strength of the shear: when the shear attained large values, an episode of billows occurred, followed by a sharp decrease in the shear. The occurrence of large values of shear and Kelvin–Helmholtz billows over two different mountain ranges suggests that they may be important features occurring when extratropical cyclones with statically stable flow pass over mountain ranges.

  8. A modelling case study of a large-scale cirrus in the tropical tropopause layer

    Science.gov (United States)

    Podglajen, A.; Plougonven, R.; Hertzog, A.; Legras, B.

    2015-11-01

    We use the Weather Research and Forecast (WRF) model to simulate a large-scale tropical tropopause layer (TTL) cirrus, in order to understand the formation and life cycle of the cloud. This cirrus event has been previously described through satellite observations by Taylor et al. (2011). Comparisons of the simulated and observed cirrus show a fair agreement, and validate the reference simulation regarding cloud extension, location and life time. The validated simulation is used to understand the causes of cloud formation. It is shown that several cirrus clouds successively form in the region due to adiabatic cooling and large-scale uplift rather than from ice lofting from convective anvils. The equatorial response (equatorial wave excitation) to a midlatitude potential vorticity (PV) intrusion structures the uplift. Sensitivity tests are then performed to assess the relative importance of the choice of the microphysics parametrisation and of the initial and boundary conditions. The initial dynamical conditions (wind and temperature) essentially control the horizontal location and area of the cloud. On the other hand, the choice of the microphysics scheme influences the ice water content and the cloud vertical position. Last, the fair agreement with the observations allows to estimate the cloud impact in the TTL in the simulations. The cirrus clouds have a small but not negligible impact on the radiative budget of the local TTL. However, the cloud radiative heating does not significantly influence the simulated dynamics. The simulation also provides an estimate of the vertical redistribution of water by the cloud and the results emphasize the importance in our case of both re and dehydration in the vicinity of the cirrus.

  9. A modelling case study of a large-scale cirrus in the tropical tropopause layer

    Science.gov (United States)

    Podglajen, Aurélien; Plougonven, Riwal; Hertzog, Albert; Legras, Bernard

    2016-03-01

    We use the Weather Research and Forecast (WRF) model to simulate a large-scale tropical tropopause layer (TTL) cirrus in order to understand the formation and life cycle of the cloud. This cirrus event has been previously described through satellite observations by Taylor et al. (2011). Comparisons of the simulated and observed cirrus show a fair agreement and validate the reference simulation regarding cloud extension, location and life time. The validated simulation is used to understand the causes of cloud formation. It is shown that several cirrus clouds successively form in the region due to adiabatic cooling and large-scale uplift rather than from convective anvils. The structure of the uplift is tied to the equatorial response (equatorial wave excitation) to a potential vorticity intrusion from the midlatitudes. Sensitivity tests are then performed to assess the relative importance of the choice of the microphysics parameterization and of the initial and boundary conditions. The initial dynamical conditions (wind and temperature) essentially control the horizontal location and area of the cloud. However, the choice of the microphysics scheme influences the ice water content and the cloud vertical position. Last, the fair agreement with the observations allows to estimate the cloud impact in the TTL in the simulations. The cirrus clouds have a small but not negligible impact on the radiative budget of the local TTL. However, for this particular case, the cloud radiative heating does not significantly influence the simulated dynamics. This result is due to (1) the lifetime of air parcels in the cloud system, which is too short to significantly influence the dynamics, and (2) the fact that induced vertical motions would be comparable to or smaller than the typical mesoscale motions present. Finally, the simulation also provides an estimate of the vertical redistribution of water by the cloud and the results emphasize the importance in our case of both

  10. An intimate coupling of ocean-atmospheric interaction over the extratropical North Atlantic and Pacific

    Science.gov (United States)

    Li, Chun; Wu, Lixin; Wang, Qi; Qu, Liwei; Zhang, Liping

    2009-05-01

    The inter-basin teleconnection between the North Atlantic and the North Pacific ocean-atmosphere interaction is studied using a coupled ocean-atmosphere general circulation model. In the model, an idealized oceanic temperature anomaly is initiated over the Kuroshio and the Gulf Stream extension region to track the coupled evolution of ocean and atmosphere interaction, respectively. The experiments explicitly demonstrate that both the North Pacific and the North Atlantic ocean-atmosphere interactions are intimately coupled through an inter-basin atmospheric teleconnection. This fast inter-basin communication can transmit oceanic variability between the North Atlantic and the North Pacific through local ocean-to-atmosphere feedbacks. The leading mode of the extratropical atmospheric internal variability plays a dominant role in shaping the hemispheric-scale response forced by oceanic variability over the North Atlantic and Pacific. Modeling results also suggest that a century (two centuries) long observations are necessary for the detection of Pacific response to Atlantic forcings (Atlantic response to Pacific forcing).

  11. Evidence for Tropopause Layer Moistening by Convection During CRYSTAL-FACE

    Science.gov (United States)

    Ackerman, A.; Fridlind, A.; Jensen, E.; Miloshevich, L.; Heymsfield, G.; McGill, M.

    2003-01-01

    Measurements and analysis of the impact of deep convection on tropopause layer moisture are easily confounded by difficulties making precise observations with sufficient spatial coverage before and after convective events and difficulties distinguishing between changes due to local convection versus large-scale advection. The interactions between cloud microphysics and dynamics in the convective transport of moisture into the tropopause layer also result in a sufficiently complex and poorly characterized system to allow for considerable freedom in theoretical models of stratosphere-troposphere exchange. In this work we perform detailed large-eddy simulations with an explicit cloud microphysics model to study the impact of deep convection on tropopause layer moisture profiles observed over southern Florida during CRYSTALFACE. For four days during the campaign (July 11, 16, 28, and 29) we initialize a 100-km square domain with temperature and moisture profiles measured prior to convection at the PARSL ground site, and initiate convection with a warm bubble that produces an anvil at peak elevations in agreement with lidar and radar observations on that day. Comparing the moisture field after the anvils decay with the initial state, we find that convection predominantly moistens the tropopause layer (as defined by minimum temperature and minimum potential temperature lapse rate), although some drying is also predicted in localized layers. We will also present results of sensitivity tests designed to separate the roles of cloud microphysics and dynamics.

  12. COSMIC Radio Occultation technique for measurement of the tropopause during tropical cyclones

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, Stig

    variation at the tropopause is seen in the standard RO data products like water vapour pressure and temperature profiles, the GPS signal bending angle profile shows a TC signature in the upper troposphere. The presentation is focused on two particular TCs, the hurricane Bertha, which formed in the Atlantic...

  13. Robustness of serial clustering of extratropical cyclones to the choice of tracking method

    Directory of Open Access Journals (Sweden)

    Joaquim G. Pinto

    2016-07-01

    Full Text Available Cyclone clusters are a frequent synoptic feature in the Euro-Atlantic area. Recent studies have shown that serial clustering of cyclones generally occurs on both flanks and downstream regions of the North Atlantic storm track, while cyclones tend to occur more regulary on the western side of the North Atlantic basin near Newfoundland. This study explores the sensitivity of serial clustering to the choice of cyclone tracking method using cyclone track data from 15 methods derived from ERA-Interim data (1979–2010. Clustering is estimated by the dispersion (ratio of variance to mean of winter [December – February (DJF] cyclone passages near each grid point over the Euro-Atlantic area. The mean number of cyclone counts and their variance are compared between methods, revealing considerable differences, particularly for the latter. Results show that all different tracking methods qualitatively capture similar large-scale spatial patterns of underdispersion and overdispersion over the study region. The quantitative differences can primarily be attributed to the differences in the variance of cyclone counts between the methods. Nevertheless, overdispersion is statistically significant for almost all methods over parts of the eastern North Atlantic and Western Europe, and is therefore considered as a robust feature. The influence of the North Atlantic Oscillation (NAO on cyclone clustering displays a similar pattern for all tracking methods, with one maximum near Iceland and another between the Azores and Iberia. The differences in variance between methods are not related with different sensitivities to the NAO, which can account to over 50% of the clustering in some regions. We conclude that the general features of underdispersion and overdispersion of extratropical cyclones over the North Atlantic and Western Europe are robust to the choice of tracking method. The same is true for the influence of the NAO on cyclone dispersion.

  14. Extratropical transitioning in the RMS Japan typhoon wind field model

    Science.gov (United States)

    Loridan, Thomas; Scherer, Emilie; Khare, Shree

    2013-04-01

    Given its meridional extent and location within the Pacific basin, Japan is regularly impacted by strong winds from cyclones at different stages of their lifecycle. To quantify the associated risk of damage to properties, catastrophe models such as the ones developed by RMS aim to simulate wind fields from thousands of stochastic storms that extrapolate historical events. In a recent study using 25 years of reanalysis data, Kitabatake (2011) estimated that 40 % of all Pacific tropical cyclones completed their transition as an extra tropical system. From a cat modelling point of view it is the increase in wind field asymmetry observed during these transitioning episodes that is critical, with examples like typhoon Tokage in 2004 showing the potential for damaging gusts on both sides of the storm track. In this context a compromise has to be found between the need for complex numerical models able to simulate wind field variability around the cyclone during its entire evolution, and obvious running time constrains. The RMS wind field model is based on an optimized version of the Willoughby parametric profile (Willoughby et al., 2006) which requires calibration against targets representative of cyclone wind fields throughout their lifecycle. We here present the different sources of data involved in the development of this model. This includes (1) satellite products to characterize wind fields from fully tropical storms, (2) high resolution simulations of key transitioning events using the WRF mesoscale model to complement the database at other stages (i.e. for transitioning and fully extra tropical wind fields), and (3) reanalysis data which can be used with Hart (2003)'s cyclone phase space methodology to provide an estimate of the mean duration of transitioning episodes in the Pacific. Kitabatake, N., 2011: Climatology of extratropical transition of tropical cyclones in the Western North Pacific defined by using cyclone phase space. J. Meteor. Soc. Japan, 89, 309

  15. The extra-tropical NH temperature in the last two millennia: reconstructions of low-frequency variability

    Directory of Open Access Journals (Sweden)

    B. Christiansen

    2011-11-01

    Full Text Available We present two new multi-proxy reconstructions of the extra-tropical Northern Hemisphere (30–90° N mean temperature: a two-millennia long reconstruction reaching back to AD 1 based on 32 proxies and a 500-yr long reconstruction reaching back to AD 1500 based on 91 proxies. The proxies are of different types and of different resolutions (annual, annual-to-decadal, and decadal but all have previously been shown to relate to local or regional temperature. We use a reconstruction method, LOC, that recently has been shown to confidently reproduce low-frequency variability. Confidence intervals are obtained by an ensemble pseudo-proxy method that both estimates the variance and the bias of the reconstructions. The two-millennia long reconstruction shows a well defined Medieval Warm Period with a peak warming ca. AD 950–1050 reaching 0.7 °C relative to the reference period AD 1880–1960. The 500-yr long reconstruction confirms previous results obtained with the LOC method applied to a smaller proxy compilation; in particular it shows the Little Ice Age cumulating in AD 1580–1720 with a temperature minimum of −1.1 °C below the reference period. The reconstructed local temperatures, the magnitude of which are subject to wide confidence intervals, show a rather geographically homogeneous LIA while more geographical inhomogeneities are found for the Medieval Warm Period. Reconstructions based on different number of proxies show only small differences suggesting that LOC reconstructs 50-yr smoothed extra-tropical NH mean temperatures well and that low-frequency noise in the proxies is a relatively small problem.

  16. Decadal variability of tropical tropopause temperature and its relationship to the Pacific Decadal Oscillation

    Science.gov (United States)

    Wang, Wuke; Matthes, Katja; Omrani, Nour-Eddine; Latif, Mojib

    2016-07-01

    Tropopause temperatures (TPTs) control the amount of stratospheric water vapour, which influences chemistry, radiation and circulation in the stratosphere, and is also an important driver of surface climate. Decadal variability and long-term trends in tropical TPTs as well as stratospheric water vapour are largely unknown. Here, we present for the first time evidence, from reanalysis and state-of-the-art climate model simulations, of a link between decadal variability in tropical TPTs and the Pacific Decadal Oscillation (PDO). The negative phase of the PDO is associated with anomalously cold sea surface temperatures (SSTs) in the tropical east and central Pacific, which enhance the zonal SST gradient across the equatorial Pacific. The latter drives a stronger Walker Circulation and a weaker Hadley Circulation, which leads to less convection and subsequently a warmer tropopause over the central equatorial Pacific. Over the North Pacific, positive sea level pressure anomalies occur, which damp vertical wave propagation into the stratosphere. This in turn slows the Brewer-Dobson circulation, and hence warms the tropical tropopause, enabling more water vapour to enter the stratosphere. The reverse chain of events holds for the positive phase of the PDO. Such ocean-troposphere-stratosphere interactions may provide an important feedback on the Earth’s global surface temperature.

  17. How will climate change affect explosive cyclones in the extratropics of the Northern Hemisphere?

    Science.gov (United States)

    Seiler, C.; Zwiers, F. W.

    2016-06-01

    Explosive cyclones are rapidly intensifying low pressure systems generating severe wind speeds and heavy precipitation primarily in coastal and marine environments. This study presents the first analysis on how explosive cyclones respond to climate change in the extratropics of the Northern Hemisphere. An objective-feature tracking algorithm is used to identify and track cyclones from 23 CMIP5 climate models for the recent past (1981-1999) and future (2081-2099). Explosive cyclones are projected to shift northwards by about 2.2^circ latitude on average in the northern Pacific, with fewer and weaker events south of 45^circ hbox {N}, and more frequent and stronger events north of this latitude. This shift is correlated with a poleward shift of the jet stream in the inter-model spread (R=0.56). In the Atlantic, the total number of explosive cyclones is projected to decrease by about 17 % when averaging across models, with the largest changes occurring along North America's East Coast. This reduction is correlated with a decline in the lower-tropospheric Eady growth rate (R=0.51), and is stronger for models with smaller frequency biases (R=-0.65). The same region is also projected to experience a small intensification of explosive cyclones, with larger vorticity values for models that predict stronger increases in the speed of the jet stream (R=0.58). This strengthening of the jet stream is correlated with an enhanced sea surface temperature gradient in the North Atlantic (R=-0.63). The inverse relationship between model bias and projection, and the role of model resolution are discussed.

  18. CO2 and albedo climate impacts of extratropical carbon and biomass plantations

    NARCIS (Netherlands)

    Schaeffer, M.; Eickhout, B.; Hoogwijk, M.; Strengers, B.; Vuuren, van D.J.; Leemans, R.; Opsteegh, T.

    2006-01-01

    We explored the climate impacts for two land-use change scenarios, aimed at mitigating the buildup of greenhouse gases in the atmosphere. Using the integrated assessment model IMAGE 2.2, we found that the large-scale implementation in the extratropics of either carbon-sequestration or modern-biomass

  19. A link between high-speed solar wind streams and explosive extratropical cyclones

    Science.gov (United States)

    Prikryl, Paul; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Bruntz, Robert

    2016-11-01

    A link between solar wind magnetic sector boundary (heliospheric current sheet) crossings by the Earth and the upper-level tropospheric vorticity was discovered in the 1970s. These results have been later confirmed but the proposed mechanisms remain controversial. Extratropical-cyclone tracks obtained from two meteorological reanalysis datasets are used in superposed epoch analysis of time series of solar wind plasma parameters and green coronal emission line intensity. The time series are keyed to times of maximum growth of explosively developing extratropical cyclones in the winter season. The new statistical evidence corroborates the previously published results (Prikryl et al., 2009). This evidence shows that explosive extratropical cyclones tend to occur after arrivals of solar wind disturbances such as high-speed solar wind streams from coronal holes when large amplitude magneto-hydrodynamic waves couple to the magnetosphere-ionosphere system. These MHD waves modulate Joule heating and/or Lorentz forcing of the high-latitude thermosphere generating medium-scale atmospheric gravity waves that propagate energy upward and downward from auroral zone through the atmosphere. At the tropospheric level, in spite of significantly reduced amplitudes, these gravity waves can provide a lift of unstable air to release the moist symmetric instability thus initiating slantwise convection and forming cloud/precipitation bands. The release of latent heat is known to provide energy for rapid development and intensification of extratropical cyclones.

  20. 76 FR 74776 - Forum-Trends in Extreme Winds, Waves, and Extratropical Storms Along the Coasts

    Science.gov (United States)

    2011-12-01

    ... National Oceanic and Atmospheric Administration Forum--Trends in Extreme Winds, Waves, and Extratropical... open public forum. SUMMARY: This notice sets forth the schedule and topics of an upcoming forum hosted... the forum and are required to RSVP to Brooke.Stewart@noaa.gov by 5 p.m. EST, Wednesday, December 28...

  1. Transport across the tropical tropopause layer and convection

    Science.gov (United States)

    Tissier, Ann-Sophie; Legras, Bernard; Tzella, Alexandra

    2015-04-01

    We investigate how air parcels detrained from convective sources enter the TTL. The approach is based on the comparison of unidimensional trajectories and Lagrangian backward and forward trajectories, using TRACZILLA and ERA-Interim. Backward trajectories are launched at 380K and run until they hit a deep convective cloud. Forward trajectories are launched at the top of high convective clouds identified by brightness temperature from CLAUS dataset. 1D trajectories are computed using Gardiner's method. Results show that the warm pool region during winter and the Bay of Bengal / Sea of China during summer are the prevalent sources as already identified in many previous studies and we quantify the respective role of the various regions. We show that the 1D model explains qualitatively and often quantitatively the 3d results. We also show that in spite of generating very high convection, Africa is quite ineffective as providing air that remains in the TTL while on the opposite the Tibetan Plateau is the most effective region in this respect although its total contribution is minor. Finally, we compare ERA-Interim, JRA-55 and MERRA reanalysis and find large similarities between the two formers.

  2. The role of large-scale, extratropical dynamics in climate change

    Energy Technology Data Exchange (ETDEWEB)

    Shepherd, T.G. [ed.

    1994-02-01

    The climate modeling community has focused recently on improving our understanding of certain processes, such as cloud feedbacks and ocean circulation, that are deemed critical to climate-change prediction. Although attention to such processes is warranted, emphasis on these areas has diminished a general appreciation of the role played by the large-scale dynamics of the extratropical atmosphere. Lack of interest in extratropical dynamics may reflect the assumption that these dynamical processes are a non-problem as far as climate modeling is concerned, since general circulation models (GCMs) calculate motions on this scale from first principles. Nevertheless, serious shortcomings in our ability to understand and simulate large-scale dynamics exist. Partly due to a paucity of standard GCM diagnostic calculations of large-scale motions and their transports of heat, momentum, potential vorticity, and moisture, a comprehensive understanding of the role of large-scale dynamics in GCM climate simulations has not been developed. Uncertainties remain in our understanding and simulation of large-scale extratropical dynamics and their interaction with other climatic processes, such as cloud feedbacks, large-scale ocean circulation, moist convection, air-sea interaction and land-surface processes. To address some of these issues, the 17th Stanstead Seminar was convened at Bishop`s University in Lennoxville, Quebec. The purpose of the Seminar was to promote discussion of the role of large-scale extratropical dynamics in global climate change. Abstracts of the talks are included in this volume. On the basis of these talks, several key issues emerged concerning large-scale extratropical dynamics and their climatic role. Individual records are indexed separately for the database.

  3. The influence of an atmospheric Two-Way coupled model system on the predictability of extratropical cyclones

    Science.gov (United States)

    Schuster, Mareike; Thürkow, Markus; Weiher, Stefan; Kirchner, Ingo; Ulbrich, Uwe; Will, Andreas

    2016-04-01

    A general bias of global atmosphere ocean models, and also of the MPI-ESM, is an under-representation of the high latitude cyclone activity and an overestimation of the mid latitude cyclone activity in the North Atlantic, thus representing the extra-tropical storm track too zonal. We will show, that this effect can be antagonized by applying an atmospheric Two-Way Coupling (TWC). In this study we present a newly developed Two-Way Coupled model system, which is based on the MPI-ESM, and show that it is able to capture the mean storm track location more accurate. It also influences the sub-decadal deterministic predictability of extra-tropical cyclones and shows significantly enhanced skill compared to the "uncoupled" MPI-ESM standalone system. This study evaluates a set of hindcast experiments performed with said Two-Way Coupled model system. The regional model COSMO CLM is Two-Way Coupled to the atmosphere of the global Max-Plack-Institute Earth System Model (MPI-ESM) and therefore integrates and exchanges the state of the atmosphere every 10 minutes (MPI-TWC-ESM). In the coupled source region (North Atlantic), mesoscale processes which are relevant for the formation and early-stage development of cyclones are expected to be better represented, and therefore influence the large scale dynamics of the target region (Europe). The database covers 102 "uncoupled" years and 102 Two-Way Coupled years of the recent climate (1960-2010). Results are validated against the ERA-Interim reanalysis. Besides the climatological point of view, the design of this single model ensemble allows for an analysis of the predictability of the first and second leadyears of the hindcasts. As a first step to understand the improved predictability of cyclones, we will show a detailed analysis of climatologies for specific cyclone categories, sorted by season and region. Especially for cyclones affecting Europe, the TWC is capable to counteract the AOGCM's biases in the North Atlantic. Also

  4. The 1985/86 Intraseasonal Oscillation and the Role of the Extratropics.

    Science.gov (United States)

    Hsu, Huang-Hsiung; Hoskins, Brian J.; Jin, Fei-Fei

    1990-04-01

    An intraseasonal oscillation that occurred in the 1985/86 northern winter is documented in this study. The tropical convection of this event is dominated by the mixture of a standing oscillation over the maritime continent and an eastward moving feature from the Indian Ocean into the central Pacific. The time evolution of the upper tropospheric circulation patterns, instead of propagating eastward along the equator as suggested in the existing composites of the intraseasonal oscillation, is characterized by a series of wave patterns in the Northern Hemisphere and does not complete the cycle around the globe.The familiar moist Kelvin wave explanation for the intraseasonal oscillation receives little support from diagnosis of this event using zonal wind, height field, streamfunction, and potential vorticity. Only in the lower troposphere near the date line is the convincing evidence for its existence found.A scenario for the intraseasonal oscillation, which is suggested by the analysis, includes the initiation of the event through organization of tropical convection in the Indian Ocean by a subtropical Rossby wave train. This wave train also triggers a modal meridional dipole response in the west Pacific. The eastern Asia and western Pacific portion of this wave pattern is further reinforced by downstream propagation from the Indian Ocean convection region. The wave train creates the conditions in which synoptic cold surge events can occur over China. The propagation of these surges into the Indonesian region leads to markedly increased convection there. This process may be aided by the conditions created by a tongue of high potential vorticity that is advected equatorward and westward towards the Indonesian region by the flow associated with the dipole. The Indonesian convection gives rise to a North Pacific wave pattern and increased upper tropospheric, equatorial westerlies in the eastern Pacific.Aspects of this scenario are supported with previous theoretical

  5. Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: a case study on cyclone Davina (1999

    Directory of Open Access Journals (Sweden)

    F. Cairo

    2008-07-01

    Full Text Available During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame.

    Temperature anomalies in the tropical tropopause layer (TTL, warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone was observed and perturbed water distribution in the TTL was documented. The paper discuss possible processes of dehydration induced by the cirrus forming above the cyclone, and change in the chemical tracer and water distribution in the lower stratosphere 400–430 K due to meridional transport from the mid-latitudes and link with Davina. Moreover it compares the data prior and after the cyclone passage to discuss its actual impact on the atmospheric chemistry and thermodynamics.

  6. Impact of deep convection in the tropical tropopause layer in West Africa: in-situ observations and mesoscale modelling

    Directory of Open Access Journals (Sweden)

    F. Fierli

    2011-01-01

    Full Text Available We present the analysis of the impact of convection on the composition of the tropical tropopause layer region (TTL in West-Africa during the AMMA-SCOUT campaign. Geophysica M55 aircraft observations of water vapor, ozone, aerosol and CO2 during August 2006 show perturbed values at altitudes ranging from 14 km to 17 km (above the main convective outflow and satellite data indicates that air detrainment is likely to have originated from convective cloud east of the flights. Simulations of the BOLAM mesoscale model, nudged with infrared radiance temperatures, are used to estimate the convective impact in the upper troposphere and to assess the fraction of air processed by convection. The analysis shows that BOLAM correctly reproduces the location and the vertical structure of convective outflow. Model-aided analysis indicates that convection can influence the composition of the upper troposphere above the level of main outflow for an event of deep convection close to the observation site. Model analysis also shows that deep convection occurring in the entire Sahelian transect (up to 2000 km E of the measurement area has a non negligible role in determining TTL composition.

  7. Impact of deep convection in the tropical tropopause layer in West Africa: in-situ observations and mesoscale modelling

    Science.gov (United States)

    Fierli, F.; Orlandi, E.; Law, K. S.; Cagnazzo, C.; Cairo, F.; Schiller, C.; Borrmann, S.; di Donfrancesco, G.; Ravegnani, F.; Volk, C. M.

    2011-01-01

    We present the analysis of the impact of convection on the composition of the tropical tropopause layer region (TTL) in West-Africa during the AMMA-SCOUT campaign. Geophysica M55 aircraft observations of water vapor, ozone, aerosol and CO2 during August 2006 show perturbed values at altitudes ranging from 14 km to 17 km (above the main convective outflow) and satellite data indicates that air detrainment is likely to have originated from convective cloud east of the flights. Simulations of the BOLAM mesoscale model, nudged with infrared radiance temperatures, are used to estimate the convective impact in the upper troposphere and to assess the fraction of air processed by convection. The analysis shows that BOLAM correctly reproduces the location and the vertical structure of convective outflow. Model-aided analysis indicates that convection can influence the composition of the upper troposphere above the level of main outflow for an event of deep convection close to the observation site. Model analysis also shows that deep convection occurring in the entire Sahelian transect (up to 2000 km E of the measurement area) has a non negligible role in determining TTL composition.

  8. Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: a case study on cyclone Davina (1999)

    Science.gov (United States)

    Cairo, F.; Buontempo, C.; MacKenzie, A. R.; Schiller, C.; Volk, C. M.; Adriani, A.; Mitev, V.; Matthey, R.; di Donfrancesco, G.; Oulanovsky, A.; Ravegnani, F.; Yushkov, V.; Snels, M.; Cagnazzo, C.; Stefanutti, L.

    2008-07-01

    During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame. Temperature anomalies in the tropical tropopause layer (TTL), warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone was observed and perturbed water distribution in the TTL was documented. The paper discuss possible processes of dehydration induced by the cirrus forming above the cyclone, and change in the chemical tracer and water distribution in the lower stratosphere 400 430 K due to meridional transport from the mid-latitudes and link with Davina. Moreover it compares the data prior and after the cyclone passage to discuss its actual impact on the atmospheric chemistry and thermodynamics.

  9. Diagnosis of processes controlling water vapour in the tropical tropopause layer by a Lagrangian cirrus model

    Directory of Open Access Journals (Sweden)

    C. Ren

    2007-04-01

    Full Text Available We have developed a Lagrangian air-parcel cirrus model (LACM, to diagnose the processes controlling water in the tropical tropopause layer (TTL. LACM applies parameterised microphysics to air parcel trajectories. The parameterisation includes the homogeneous freezing of aerosol droplets, the growth/sublimation of ice particles, and sedimentation of ice particles, so capturing the main dehydration mechanism for air in the TTL. Rehydration is also considered by resetting the water vapour mixing ratio in an air parcel to the value at the point in the 4-D analysis/forecast data used to generate the trajectories, but only when certain conditions, indicative of convection, are satisfied. These conditions are imposed to confine what processes contribute to rehydration. The conditions act to restrict rehydration of the Lagrangian air parcels to regions where convective transport of water vapour from below is significant, at least to the extent that the analysis/forecast captures this process. The inclusion of hydration and dehydration mechanisms in LACM results in total water fields near tropical convection that have more of the "stripey" character of satellite observations of high cloud, than do either the ECMWF analysis or trajectories without microphysics.

    The mixing ratios of total water in the TTL, measured by a high-altitude aircraft over Brazil (during the TROCCINOX campaign, have been reconstructed by LACM using trajectories generated from ECMWF analysis. Two other Lagrangian reconstructions are also tested: linear interpolation of ECMWF analysed specific humidity onto the aircraft flight track, and instantaneous dehydration to the saturation vapour pressure over ice along trajectories. The reconstructed total water mixing ratios along aircraft flight tracks are compared with observations from the FISH total water hygrometer. Process-oriented analysis shows that modelled cirrus cloud events are responsible for dehydrating the air

  10. Estudo de caso de ciclone extratropical sobre a América do Sul: sensibilidade das análises Case study of extratropical cyclone over the South America: sensibility of analysis

    Directory of Open Access Journals (Sweden)

    David Mendes

    2009-12-01

    Full Text Available A trajetória e a energética de um ciclone extratropical são analisadas usando as reanálises do NCEP/NCAR, em comparação com as saídas do modelo CPTEC/COLA (T126L28 com análises do GPSAS. A analise da energética e da trajetória de um ciclone, formado no leste da Argentina em 23 de Agosto de 2005, mostrou diferenças significativas entre as reanálises e o modelo, principalmente na sua trajetória e magnitude. A comparação da evolução do ciclone extratropical entre as reanálises e o modelo, mostrou alguns resultados consideráveis, tais como: maior diferença na intensidade da pressão central do ciclone extratropical; maiores diferenças na Energia Cinética após a máxima intensidade do ciclone, e diferenças marcantes no posicionamento do ciclone extratropical.The trajectory and the energetic of extratropical cyclones are analyzed using the NCEP/NCAR reanalysis in comparison with the model outputs CPTEC/COLA (T126L28 with GPSAS analysis. The analysis of the energetic and path of the cyclone formed over East Argentina on 23 August 2005 showed significant differences between the reanalysis and the model, especially in its track and magnitude. The comparison of the extratropical cyclone evolution, between reanalysis and the model, showed some considerable results such as: greater difference in the central pressure intensity of the extratropical cyclones; larger differences in kinetic energy after maximum cyclone intensity and a striking difference in the extratropical cyclone position.

  11. Structural and Environmental Characteristics of Extratropical Cyclones that Cause Tornado Outbreaks in the Warm Sector

    Science.gov (United States)

    Tochimoto, Eigo; Niino, Hiroshi

    2016-04-01

    The differences in structural and environmental characteristics of extratropical cyclones (hereafter, ECs) that cause tornado outbreaks and those that do not were examined through composite analyses of the newly-released Japanese reanalysis data (JRA-55) and idealized numerical experiments. ECs that developed in the United States in April and May between 1995 and 2012 are categorized into two groups: ECs accompanied by 15 or more tornadoes (hereafter, outbreak cyclones (OCs)) and ECs accompanied by 5 or less tornadoes (non-outbreak cyclones (NOCs)). 55 OCs and 41 NOCs that are of similar strength as OCs are selected in this study. The composite analyses show significant differences in convective environmental parameters between OCs and NOCs. For OCs, convective available potential energy (CAPE) and storm relative environmental helicity (SREH) are larger and the areas in which these parameters have significant values are wider in the warm sector. The larger CAPE in OCs is due to larger amount of low-level water vapor, while the larger SREH in OCs due to stronger southerly wind at low levels. A piecewise potential vorticity (PV) diagnostics (Davis and Emanuel, 1991) indicates that low- to mid-level PV anomalies mainly contribute to the difference in the low-level winds between OCs and NOCs. On the other hand, the low-level winds associated with upper-level PV anomalies are not the major contributor to the difference. The results of the idealized numerical experiments for OCs and NOCs (hereafter, referred to as OC-CTL and NOC-CTL, respectively) using WRF ver. 3.4 show that the characteristics of the low-level wind fields and SREH distributions for the simulated ECs in OC-CTL and NOC-CTL are similar to those for OCs and NOCs, respectively. In OC-CTL, SREH and low-level winds in the east-southeast region of the EC center is larger than those in NOC-CTL, respectively. It is suggested that these differences are due to the structures of jetstream. The structure of

  12. A comparison of tropopause heights over China between radiosonde and three reanalysis datasets for the period 1979-2012

    Science.gov (United States)

    Liu, Hui; Li, Zhenchao; Wei, Hong; Zheng, Zhiyuan; Wei, Zhigang

    2016-07-01

    We compared the correspondence of tropopause heights over China calculated from the gridded temperature data provided by the ERA-Interim project, NCEP/NCAR Reanalysis Projects-1 (NCEP-1), and Japanese 25-year Reanalysis (JRA-25) project with the radiosonde observational data for 1979-2012. The results indicate that the annual mean ERA-Interim, NCEP-1, and JRA-25 tropopause heights are higher than observations by 203, 228, and 293 gpm, respectively. Large positive differences for the majority of subtropical China primarily contribute to this high bias. An error analysis indicates that the internal coherence of the ERA-Interim data is better than that of NCEP-1 or JRA-25. Although JRA-25 was a second-generation reanalysis, the biases of the JRA-25 and NCEP-1 data relative to the observations remain substantially larger than those of the ERA-Interim. Furthermore, a spatial and temporal comparison of trends also indicates that the ERA-Interim tropopause height changes correspond most closely to the observed trends in China. Overall, our comprehensive analysis of the three reanalysis products indicates that on both seasonal and annual bases, the ERA-Interim tropopause heights are closer to the observations than those of the NCEP-1 or JRA-25 reanalyses. Furthermore, the biases are mainly a result of the algorithm that determines the tropopause height, which is limited by the coarse vertical resolution of the input data.

  13. Ice supersaturations exceeding 100% at the cold tropical tropopause: implications for cirrus formation and dehydration

    Directory of Open Access Journals (Sweden)

    E. Jensen

    2004-11-01

    Full Text Available Recent in situ measurements at tropical tropopause temperatures as low as 187 K indicate supersaturations with respect to ice exceeding 100% with little or no ice present. In contrast, models used to simulate cloud formation near the tropopause assume a supersaturation threshold for ice nucleation of about 65% based on laboratory measurements of sulfate aerosol freezing. The high supersaturations reported here, along with cloud simulations assuming a plausible range of temperature histories in the sampled air mass, indicate that the vast majority of aerosols in the air sampled on this flight must have had supersaturation thresholds for ice nucleation exceeding 100% (i.e. near liquid water saturation at these temperatures. Possible explanations for this high threshold are that (1 the expressions used for calculating vapor pressure over supercooled water at low temperatures give values at least 20% too low, (2 most of the available aerosols had a composition that makes them much more resistant to ice nucleation than aerosols used in laboratory experiments, and (3 organic films on the aerosol surfaces reduce their accommodation coefficient for uptake of water, resulting in aerosols with more concentrated solutions when moderate-rapid cooling occurs and correspondingly inhibited homogeneous freezing. Simulations of in situ cloud formation in the tropical tropopause layer (TTL throughout the tropics indicate that if these decreased accommodation coefficients and resulting high thresholds for ice nucleation prevailed throughout the tropics, then the calculated occurrence frequency and areal coverage of TTL cirrus would be significantly suppressed. However, the simulations also show that even if in situ TTL cirrus form only over a very small fraction of the tropics in the western Pacific, enough air passes through them due to rapid horizontal transport such that they can still effectively freeze-dry air entering the stratosphere.

  14. Ice supersaturations exceeding 100% at the cold tropical tropopause: implications for cirrus formation and dehydration

    Directory of Open Access Journals (Sweden)

    E. J. Jensen

    2005-01-01

    Full Text Available Recent in situ measurements at tropical tropopause temperatures as low as 187 K indicate supersaturations with respect to ice exceeding 100% with little or no ice present. In contrast, models used to simulate cloud formation near the tropopause assume a supersaturation threshold for ice nucleation of about 65% based on laboratory measurements of aqueous aerosol freezing. The high supersaturations reported here, along with cloud simulations assuming a plausible range of temperature histories in the sampled air mass, indicate that the vast majority of aerosols in the air sampled on this flight must have had supersaturation thresholds for ice nucleation exceeding 100% (i.e. near liquid water saturation at these temperatures. Possible explanations for this high threshold are that (1 the expressions used for calculating vapor pressure over supercooled water at low temperatures give values are at least 20% too low, (2 organic films on the aerosol surfaces reduce their accommodation coefficient for uptake of water, resulting in aerosols with more concentrated solutions when moderate-rapid cooling occurs and correspondingly inhibited homogeneous freezing, and (3 if surface freezing dominates, organic coatings may increase the surface energy of the ice embryo/vapor interface resulting in suppressed ice nucleation. Simulations of in situ cloud formation in the tropical tropopause layer (TTL throughout the tropics indicate that if decreased accommodation coefficients and resulting high thresholds for ice nucleation prevailed throughout the tropics, then the calculated occurrence frequency and areal coverage of TTL cirrus would be significantly suppressed. However, the simulations also show that even if in situ TTL cirrus form only over a very small fraction of the tropics in the western Pacific, enough air passes through them due to rapid horizontal transport such that they can still effectively freeze-dry air entering the stratosphere. The TTL cirrus

  15. Diagnosis of processes controlling water vapour in the tropical tropopause layer by a Lagrangian cirrus model

    Directory of Open Access Journals (Sweden)

    C. Ren

    2007-10-01

    Full Text Available We have developed a Lagrangian air-parcel cirrus model (LACM, to diagnose the processes controlling water in the tropical tropopause layer (TTL. LACM applies parameterised microphysics to air parcel trajectories. The parameterisation includes the homogeneous freezing of aerosol droplets, the growth/sublimation of ice particles, and sedimentation of ice particles, so capturing the main dehydration mechanism for air in the TTL. Rehydration is also considered by resetting the water vapour mixing ratio in an air parcel to the value at the point in the 4-D analysis/forecast data used to generate the trajectories, but only when certain conditions, indicative of convection, are satisfied. The conditions act to restrict rehydration of the Lagrangian air parcels to regions where convective transport of water vapour from below is significant, at least to the extent that the analysis/forecast captures this process. The inclusion of hydration and dehydration mechanisms in LACM results in total water fields near tropical convection that have more of the "stripy" character of satellite observations of high cloud, than do either the ECMWF analysis or trajectories without microphysics.

    The mixing ratios of total water in the TTL, measured by a high-altitude aircraft over Brazil (during the TROCCINOX campaign, have been reconstructed by LACM using trajectories generated from ECMWF analysis. Two other Lagrangian reconstructions are also tested: linear interpolation of ECMWF analysed specific humidity onto the aircraft flight track, and instantaneous dehydration to the saturation vapour pressure over ice along trajectories. The reconstructed total water mixing ratios along aircraft flight tracks are compared with observations from the FISH total water hygrometer. Process-oriented analysis shows that modelled cirrus cloud events are responsible for dehydrating the air parcels coming from lower levels, resulting in total water mixing ratios as low as 2

  16. Multiscale asymptotics for the Skeleton of the Madden-Julian Oscillation and Tropical-Extratropical Interactions

    CERN Document Server

    Chen, Shengqian; Stechmann, Samuel N

    2015-01-01

    A new model is derived and analyzed for tropical-extratropical interactions involving the Madden-Julian oscillation (MJO). The model combines (i) the tropical dynamics of the MJO and equatorial baroclinic waves and (ii) the dynamics of barotropic Rossby waves with significant extratropical structure, and the combined system has a conserved energy. The method of multiscale asymptotics is applied to systematically derive a system of ordinary differential equations (ODEs) for three-wave resonant interactions. Two novel features are (i) a degenerate auxiliary problem with overdetermined equations due to a compatibility condition (meridional geostrophic balance) and (ii) cubic self-interaction terms that are not typically found in three-wave resonance ODEs. Several examples illustrate applications to MJO initiation and termination, including cases of (i) the MJO, equatorial baroclinic Rossby waves, and barotropic Rossby waves interacting, and (ii) the MJO, baroclinic Kelvin waves, and barotropic Rossby waves inter...

  17. The kinetic and available potential energy budget of a winter extratropical cyclone system

    OpenAIRE

    SMITH, PHILLIP J.; DARE, PATRICIA M.

    2011-01-01

    The energy budget of an extratropical cyclone system which traversed North America and intensified through the period 9–11 January 1975 is presented. The objectives of the study are (1) to document the complete energy budget of a significant winter cyclone event, and (2) to comment on the significance of latent heat release (LHR) in the cyclone's evolution. Results reveal an overall increase in both kinetic (K) and available potential energy (A). K increases are accounted for by boundary flux...

  18. Seasonal Variability of Extratropical North Pacific Wind Stress, Ekman Pumping and Sverdrup Transport

    Science.gov (United States)

    2001-12-01

    The annual cycle of the North Pacific wind stress , Ekman pumping and Sverdrup transport is investigated by means of empirical orthogonal function... stress components. These wind stress components are averaged to 624 monthly mean fields from which monthly mean Ekman pumping and Sverdrup transport...Research (NCAR) Reanalysis daily averaged surface wind components covering the extratropical North Pacific are used to calculate daily averaged wind

  19. Observations of ice nuclei and heterogeneous freezing in a Western Pacific extratropical storm

    Directory of Open Access Journals (Sweden)

    J. L. Stith

    2011-07-01

    Full Text Available In situ airborne sampling of refractory black carbon (rBC particles and Ice Nuclei (IN was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI and the residuals were sampled by a single particle soot photometer (SP2 instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here −24 to −29 °C, IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass

  20. Observations of ice nuclei and heterogeneous freezing in a Western Pacific extratropical storm

    Science.gov (United States)

    Stith, J. L.; Twohy, C. H.; Demott, P. J.; Baumgardner, D.; Campos, T.; Gao, R.; Anderson, J.

    2011-07-01

    In situ airborne sampling of refractory black carbon (rBC) particles and Ice Nuclei (IN) was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI) and the residuals were sampled by a single particle soot photometer (SP2) instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC) and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here -24 to -29 °C), IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass burning source for much

  1. Impact of missing sounding reports on mandatory levels and tropopause statistics: a case study

    Directory of Open Access Journals (Sweden)

    J. C. Antuña

    2006-10-01

    Full Text Available This paper describes the effect of missing sounding reports on temperature and pressure mean values for mandatory levels using the aerological information from the Camagüey Meteorological Centre. Also it is described the effect of missing data on mean temperature and pressure values at the multiple tropopause levels. The case study belongs to one station for a time lag of eight years. Up to the present these types of studies have been conducted using simulated datasets. The present one uses a real inhomogeneous radiosonde dataset. The main reason for missing reports were transmission problems and possible encoding-decoding difficulties. It has been found that profiles of the mean temperature and altitude show little differences between the complete and incomplete datasets. Moreover, no statistical significant differences were found for the mean values of the variables for the complete and incomplete datasets. The most probable reason for those results is that the cause of the missing reports has a random behaviour. Finally we have found that the only two effects noticed on the statistics were slightly higher values of the mean temperatures in the complete dataset and the decrease in the percent of multiple tropopause reports for the incomplete dataset.

  2. Regular, Fast and Accurate Airborne In-Situ Methane Measurements Around the Tropopause

    Science.gov (United States)

    Dyroff, Christoph; Rauthe-Schöch, Armin; Schuck, Tanja J.; Zahn, Andreas

    2013-04-01

    We present a laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft. The instrument is based on a commercial fast methane analyzer (FMA, Los Gatos Res.), which was modified for fully unattended employment. A laboratory characterization was performed and the results with emphasis on the precision, cross sensitivity to H2O, and accuracy are presented. An in-flight calibration strategy is described, that utilizes CH4 measurements obtained from flask samples taken during the same flights. By statistical comparison of the in-situ measurements with the flask samples we derive a total uncetrainty estimate of ~ 3.85 ppbv (1?) around the tropopause, and ~ 12.4 ppbv (1?) during aircraft ascent and descent. Data from the first two years of airborne operation are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere, with occasional crossings of the tropics on flights to southern Africa. With its high spatial resolution and high accuracy this data set is unprecedented in the highly important atmospheric layer of the tropopause.

  3. Intraseasonal Relationships Between Tropical Heating and Extratropical Jets

    Science.gov (United States)

    1992-12-14

    intraseasonai behavoir is found to be well correlated with heating anomalies in specific parts of the global tropics. For each of these jet regions, we use...Defense Technical Information Center 2 Cameron Station Alexandria, VA 22304-6145 2. Library, Code 52 2 Naval Postgraduate School Monterey, CA 93943-5000 3

  4. Exploring post-cold frontal moisture transport in an idealized extratropical cyclone study

    Science.gov (United States)

    Sheffield, Amanda Marie

    Moisture transport in extratropical cyclones (ETCs) has been studied in the past in the context of the warm conveyor belt (WCB), a 'conveyor belt' transferring moisture from the warm sector boundary layer to the free troposphere both eastward and poleward of the warm front. Recent research has highlighted a different, potentially important mechanism of transporting water vapor in ETCs by post-cold frontal (PCF) clouds. PCF clouds are typically boundary layer cumulus clouds located in the cold sector of an ETC that transfer moisture to the free troposphere through convective-evaporative processes. Recent studies have suggested that these PCF cumuli may vertically transport nearly equivalent amounts of moisture as the WCB. Therefore, not only are these PCF cumuli important in venting the PCF boundary layer, they also play a role in limiting the amount of moisture available for convergence in the source region of the WCB. This limitation can have important consequences for regional weather and climate through its impact on the timing and location of precipitation, the three-dimensional redistribution of water vapor, and the distribution of clouds within ETCs. The goal of this study is to investigate the role of PCF clouds in the moisture transport of an ETC, and the impacts of environmental factors such as SST and aerosol loading on this transport role. We have achieved this goal through the use of numerical simulations of such a storm system. Previous studies have utilized model simulations with relatively coarse grid resolutions and convective parameterization schemes. Here, we simulate a wintertime ETC over the Pacific Ocean using high spatial and temporal resolution, advanced microphysics and explicitly resolved convection. The results of this research demonstrate that PCF cumuli are found to vertically ventilate BL moisture over an expansive region behind the cold front. The free tropospheric moisture contents and stability profile of the cold sector exert a

  5. The synoptic-scale evolution during the extratropical transition of Irene (2011), Sandy (2012), and Andrea (2013)

    Science.gov (United States)

    Towey, Katherine Lorraine

    Tropical cyclones (TCs) of varying shapes, sizes, and intensities form in nearly every ocean basin and can potentially impact heavily populated areas, threatening human life and property. As a TC moves poleward, it can interact with a variety of synoptic-scale features, which results in either the dissipation of the TC or a transition into an extratropical cyclone (EXTC) through the process of extratropical transition (ET). Given an ideal synoptic-scale setup, a TC can transition into a fast-moving and rapidly developing EXTC, which could extend TC-like conditions such as strong surface winds and intense rainfall over a broad area at high latitudes. In recent years, three TCs, Irene (2011), Sandy (2012), and Andrea (2013), transitioned to EXTCs while approaching the middle latitudes and subsequently impacted the Northeast as EXTCs. In order to analyze the ET of these TCs, the cyclone phase space, developed by Hart (2003), was utilized. This product aids in determining the structural evolution associated with ET in which a symmetric, warm-core TC transitions to an asymmetric, cold-core EXTC. Changes in the structure, motion, and intensity of TCs during ET are highly dependent on the midlatitude environment into which the TC moves. A variety of factors contribute to the intensity of the resultant EXTC, including xix the overall large-scale pattern, track of the TC, time of year, as well as the intensity of the TC and the frontal system with which the TC interacts. Synoptic-scale features were analyzed for three phases of evolution throughout the ET process: tropical phase, transition period, and post-tropical phase. The TCs were not influenced by the upper-level flow until shortly after the onset of transition. It was not until the mid-way point of the transition period when the TC circulation was incorporated into the flow and began to exhibit baroclinic features. Due to differing tracks and TC intensities, the synoptic-scale features analyzed in each phase vary

  6. Improved SAGE II cloud/aerosol categorization and observations of the Asian tropopause aerosol layer: 1989–2005

    Directory of Open Access Journals (Sweden)

    L. W. Thomason

    2013-05-01

    Full Text Available We describe the challenges associated with the interpretation of extinction coefficient measurements by the Stratospheric Aerosol and Gas Experiment (SAGE II in the presence of clouds. In particular, we have found that tropospheric aerosol analyses are highly dependent on a robust method for identifying when clouds affect the measured extinction coefficient. Herein, we describe an improved cloud identification method that appears to capture cloud/aerosol events more effectively than early methods. In addition, we summarize additional challenges to observing the Asian Tropopause Aerosol Layer (ATAL using SAGE II observations. Using this new approach, we perform analyses of the upper troposphere, focusing on periods in which the UTLS (upper troposphere/lower stratosphere is relatively free of volcanic material (1989–1990 and after 1996. Of particular interest is the Asian monsoon anticyclone where CALIPSO (Cloud-Aerosol Lidar Pathfinder Satellite Observations has observed an aerosol enhancement. This enhancement, called the ATAL, has a similar morphology to observed enhancements in long-lived trace gas species like CO. Since the CALIPSO record begins in 2006, the question of how long this aerosol feature has been present requires a new look at the long-lived SAGE II data sets despite significant hurdles to its use in the subtropical upper troposphere. We find that there is no evidence of ATAL in the SAGE II data prior to 1998. After 1998, it is clear that aerosol in the upper troposphere in the ATAL region is substantially enhanced relative to the period before that time. In addition, the data generally supports the presence of the ATAL beginning in 1999 and continuing through the end of the mission, though some years (e.g., 2003 are complicated by the presence of episodic enhancements most likely of volcanic origin.

  7. Model study of the influence of cross-tropopause O3 transports on tropospheric O3 levels

    NARCIS (Netherlands)

    Roelofs, G.J.; Lelieveld, J.

    1997-01-01

    Cross-tropopause transport of O3 is a significant factor in the tropospheric budget and distribution of O3. Nevertheless, the distribution in the troposphere of O3 that originates from the stratosphere is uncertain. We study this with a chemistry - general circulation model with relatively high spat

  8. Quantifying contributions to the recent temperature variability in the tropical tropopause layer

    Directory of Open Access Journals (Sweden)

    W. Wang

    2014-08-01

    Full Text Available The recently observed variability in the tropical tropopause layer, which features an unexpected warming of 1.1 K over the past decade (2001–2011, is investigated with a number of sensitivity experiments from simulations with NCAR's CESM-WACCM chemistry climate model. The experiments have been designed to specifically quantify the contributions from natural as well as anthropogenic factors, such as solar variability (Solar, sea surface temperatures (SSTs, the Quasi-Biennial Oscillation (QBO, stratospheric aerosols (Aerosol, greenhouse gases (GHGs, as well as the dependence on the vertical resolution in the model. The results show that, in the TTL: a cooling in tropical SSTs leads to a weakening of tropical upwelling around the tropical tropopause and hence relative downwelling and adiabatic warming of 0.3 K decade−1; an increased QBO amplitude results in a 0.3 K decade−1 warming; increasing aerosols in the lower stratosphere lead to a 0.4 K decade−1 warming; a prolonged solar minimum and increased GHGs contribute about 0.2 and 0.1 K decade−1 to a cooling, respectively. Two simulations with different vertical resolution show that the vertical resolution can strongly influence the response of the TTL temperature to changes such as SSTs. With higher vertical resolution, an extra 0.6 K decade−1 warming can be simulated through the last decade, compared with results from the "standard" low vertical resolution simulation. Considering all the factors mentioned above, we compute a net 1.3 K decade−1 warming, which is in very good agreement with the observed 1.1 K decade−1 warming over the past decade in the TTL. The model results indicate that the recent warming in the TTL is mainly due to internal variability, i.e. the QBO and tropical SSTs.

  9. Tropical tropopause ice clouds: a dynamic approach to the mystery of low crystal numbers

    Directory of Open Access Journals (Sweden)

    P. Spichtinger

    2013-10-01

    Full Text Available The occurrence of high, persistent ice supersaturation inside and outside cold cirrus in the tropical tropopause layer (TTL remains an enigma that is intensely debated as the "ice supersaturation puzzle". However, it was recently confirmed that observed supersaturations are consistent with very low ice crystal concentrations, which is incompatible with the idea that homogeneous freezing is the major method of ice formation in the TTL. Thus, the tropical tropopause "ice supersaturation puzzle" has become an "ice nucleation puzzle". To explain the low ice crystal concentrations, a number of mainly heterogeneous freezing methods have been proposed. Here, we reproduce in situ measurements of frequencies of occurrence of ice crystal concentrations by extensive model simulations, driven by the special dynamic conditions in the TTL, namely the superposition of slow large-scale updraughts with high-frequency short waves. From the simulations, it follows that the full range of observed ice crystal concentrations can be explained when the model results are composed from scenarios with consecutive heterogeneous and homogeneous ice formation and scenarios with pure homogeneous ice formation occurring in very slow (−1 and faster (> 1 cm s−1 large-scale updraughts, respectively. This statistical analysis shows that about 80% of TTL cirrus can be explained by "classical" homogeneous ice nucleation, while the remaining 20% stem from heterogeneous and homogeneous freezing occurring within the same environment. The mechanism limiting ice crystal production via homogeneous freezing in an environment full of gravity waves is the shortness of the gravity waves, which stalls freezing events before a higher ice crystal concentration can be formed.

  10. Simulated sensitivity of the tropical climate to extratropical thermal forcing: tropical SSTs and African land surface

    Science.gov (United States)

    Talento, Stefanie; Barreiro, Marcelo

    2016-08-01

    This study investigates the Intertropical Convergence Zone (ITCZ) response to extratropical thermal forcing applied to an atmospheric general circulation model coupled to slab ocean and land models. We focus on the relative roles of the atmosphere, tropical sea surface temperatures (SSTs) and continental surface temperatures in the ITCZ response to the imposed forcing. The forcing consists of cooling in one hemisphere and warming in the other poleward of 40°, with zero global average. Three sets of experiments are performed: in the first the slab ocean and land models are applied globally; in the second the tropical SSTs are kept fixed while the slab land model is applied globally; in the third, in addition, surface temperatures over Africa are kept fixed. Realistic boundary surface conditions are used. We find that the ITCZ shifts towards the warmer hemisphere and that the stronger the forcing, the larger the shift. When the constraint of fixed tropical SST is imposed we find that the ITCZ response is strongly weakened, but it is still not negligible in particular over the Atlantic Ocean and Africa where the precipitation anomalies are of the order of 20 and 60 %, respectively, of the magnitude obtained without the SST restriction. Finally, when the constraint of the African surface temperature is incorporated we find that the ITCZ response completely vanishes, indicating that the ITCZ response to the extratropical forcing is not possible just trough purely atmospheric processes, but needs the involvement of either the tropical SST or the continental surface temperatures. The clear-sky longwave radiation feedback is highlighted as the main physical mechanism operating behind the land-based extratropical to tropical communication.

  11. Tropical-Extratropical Interactions and Intrasasonal Oscillations in the Indian Monsoon System in a Warmer Planet

    Science.gov (United States)

    Carvalho, L. V.; Jones, C.; Cannon, F.; Norris, J.

    2015-12-01

    The India summer monsoon (ISM) experiences long periods of wet and dry conditions frequently associated with floods and long dry spells. These events are largely governed by northward propagating boreal summer monsoon intraseasonal oscillations (MISO). Here we investigate intraseasonal variability of the ISM in the climate of the 20th century using the Climate Forecast System Reanalysis (1979-2013) and examine future scenarios of climate change using models of the Coupled Model Intercomparison Project Phase-5 project. ISM is characterized with a large-scale index obtained by performing combined EOF analysis of precipitation, low level circulation, specific humidity and temperature. This index realistically defines the monsoon's onset and withdrawal, is well correlated with seasonal precipitation in India and exhibits variance on intraseasonal timescales that are related to MISO and extreme wet and dry conditions in India. With similar approach we investigate the skill of the CMIP5 models in realistically simulating MISO in the 'historic' run (1951-2005) and examine projected changes in the amplitude and persistence these events in the high-emission representative concentration pathway 8.5 (RCP8.5) (2006-2100). MISO is well characterized in CMIP5 models that indicate significant increase in the intensity and frequency of extremely dry and wet conditions affecting India by 2050. We show that the main mechanism driving MISO in CMIP5 models are linked to the propagation of extratropical wave trains and interactions with the tropics. In a warmer planet, the increase in polar temperatures weakens the tropical-extratropical temperature gradient and decreases the intensity of the upper tropospheric jet. These changes in the jet and in the baroclinic structure of the atmosphere result in enhanced extratropical wave activity and more extreme events. We use a wave tracking algorithm to demonstrate these differences and explore physical and dynamical mechanisms underlying

  12. The observed clustering of damaging extratropical cyclones in Europe

    Science.gov (United States)

    Cusack, Stephen

    2016-04-01

    The clustering of severe European windstorms on annual timescales has substantial impacts on the (re-)insurance industry. Our knowledge of the risk is limited by large uncertainties in estimates of clustering from typical historical storm data sets covering the past few decades. Eight storm data sets are gathered for analysis in this study in order to reduce these uncertainties. Six of the data sets contain more than 100 years of severe storm information to reduce sampling errors, and observational errors are reduced by the diversity of information sources and analysis methods between storm data sets. All storm severity measures used in this study reflect damage, to suit (re-)insurance applications. The shortest storm data set of 42 years provides indications of stronger clustering with severity, particularly for regions off the main storm track in central Europe and France. However, clustering estimates have very large sampling and observational errors, exemplified by large changes in estimates in central Europe upon removal of one stormy season, 1989/1990. The extended storm records place 1989/1990 into a much longer historical context to produce more robust estimates of clustering. All the extended storm data sets show increased clustering between more severe storms from return periods (RPs) of 0.5 years to the longest measured RPs of about 20 years. Further, they contain signs of stronger clustering off the main storm track, and weaker clustering for smaller-sized areas, though these signals are more uncertain as they are drawn from smaller data samples. These new ultra-long storm data sets provide new information on clustering to improve our management of this risk.

  13. Numerical prediction and potential vorticity diagnosis of extratropical cyclones

    Science.gov (United States)

    Huo, Zonghui

    By combining numerical simulations with different diagnostic tools, this thesis examines the various aspects of two explosively deepening cyclones-the superstorm of March 12-14 1993 and a storm that occurred during the Intensive Observation Period 14 (IOP-14) of the Canadian Atlantic Storm Program (CASP). Using conventional observations, the general aspects of the storms are documented and the dynamical and physical mechanisms are discussed. Then the life cycles are simulated with the Canadian Regional Finite-Element model. To improve the model initial conditions, a methodology is proposed on the basis of potential vorticity thinking, and is tested to be successful in the simulation of the March 1993 superstorm. Using the successful simulations as control runs, a series of numerical sensitivity experiments are conducted to study the impacts of model physics on the development of the two rapidly deepening cyclones. The deepening mechanisms of both storms are examined within the context of PV thinking, i.e., using piecewise potential vorticity inversion diagnostics. In both cases, the upper-level PV anomalies contribute the most to the surface cyclone, followed by the lower-level thermal anomalies and diabatic heating related moist PV anomaly. It is found that a favorable phase tilt between the upper- and lower-level PV anomalies allows a mutual interaction between them, in which the circulations associated with the upper-level anomalies enhance the lower-level anomalies, which in turn feedback positively into the upper-level PV anomalies. In addition to the vertical interactions, there also exist lateral interactions between the upper-level PV anomalies for the March 1993 superstorm. The upper-level PV features (troughs) are isolated with the piecewise PV inversion. By removing or changing the intensity of the trough in the initial conditions, the RFE model is integrated to examine the impact of each trough and its interaction with the other trough on the superstorm

  14. Rossby wave breaking, the upper level jet, and serial clustering of extratropical cyclones in western Europe

    OpenAIRE

    Priestley, Matthew D. K.; Joaquim G. Pinto; Dacre, Helen F.; Shaffrey, Len C.

    2017-01-01

    Winter 2013/14 was the stormiest on record for the UK and was characterized by recurrent clustering of extratropical cyclones. This clustering was associated with a strong, straight and persistent North Atlantic jet and was also associated with Rossby wave breaking (RWB) on both flanks, pinning the jet in place. The occurrence of RWB and cyclone clustering is further studied in 36 years of the ERA-Interim Reanalysis. Clustering at 55°N is associated with an extended and anomalously strong edd...

  15. A comparison of observed and model energy balance for an extratropical cyclone system

    Science.gov (United States)

    Dare, P. M.; Smith, P. J.

    1984-01-01

    Eddy kinetic energy budgets are presented for both moist and dry 48 h forecasts and corresponding observations of a developing winter extratropical cyclone. A diagnosis of observational data energetics is presented and compared with model results for an intense, occluding winter cyclone associated with a strong, well-developed jet stream. The nature of the eddy kinetic energy sources and sinks associated with the strong baroclinic development occurring in this cyclonic system is examined, and the extent to which to observed energy sources and sinks are present in the numerical predictions is addressed. The possibility of explaining differences between the observed and predicted cyclone systems by analyzing these kinetic energy properties is considered.

  16. Calibration and combination of seasonal climate predictions in tropical and extratropical regionals

    OpenAIRE

    Lage Rodrigues, Luis Ricardo

    2016-01-01

    Current technology allows the proliferation of multiple forecast systems developed by different research institutions from all over the world. However, most decision makers need a reliable probabilistic prediction instead of a set of predictions to take an action given the probability of an event to occur. Several studies have shown that the merging of predictions derived from several forecast systems with equal weights yields on average better predictions than the best single forecast system...

  17. Calibration and combination of seasonal climate predictions in tropical and extratropical regionals

    OpenAIRE

    Lage Rodrigues, Luis Ricardo

    2016-01-01

    [eng] Current technology allows the proliferation of multiple forecast systems developed by different research institutions from all over the world. However, most decision makers need a reliable probabilistic prediction instead of a set of predictions to take an action given the probability of an event to occur. Several studies have shown that the merging of predictions derived from several forecast systems with equal weights yields on average better predictions than the best single forecast ...

  18. Utilization of satellite cloud information to diagnose the energy state and transformations in extratropical cyclones

    Science.gov (United States)

    Smith, P. J.

    1985-01-01

    An important component of the research was a continuing investigation of the impact of latent release on extratropical cyclone development. Previous efforts to accomplish this task have focused on the energy balance and the vertical motion field of an intense winter extratropical cyclone over the United States. During this fiscal year researchers turned their attention to a more fundamental diagnostic variable, the height tendency. Central to this effort is the use of a modified form of the quasi-geostrophic height tendency equation, in which geostrophic wind components have been replaced by observed winds and a latent heat release term has been added. This methodology was adopted to produce a simple diagnostic model which retains the essential mechanisms of quasi-geostrophic theory but more faithfully describes observed wave development when the Rossby Number approaches and exceeds 0.5. Results to date indicate that the new model yields height tendencies that are superior to those obtained from the quasi-geostrophic formulation and are sufficiently close to the observed tendencies to be a useful tool for diagnosing the principle large-scale forcing mechanisms in th e700-300 mb layer. Of the three forcing terms included in the new model, vortity advection is in general dominant. The most persistent challenge to this dominance is made by the thermal advection. On the whole, latent heat release plays a secondary role. Finally, during the rapid intensification observed for this cyclone, all three processes complement each other in forcing height falls.

  19. Prevention of destructive tropical and extratropical storms, hurricanes, tornadoes, dangerous thunderstorms, and catastrophic floods

    Directory of Open Access Journals (Sweden)

    E. Yu. Krasilnikov

    2002-01-01

    Full Text Available Tropical cyclones and storms, hurricanes, powerful thunderclouds, which generate tornadoes, destructive extratropical cyclones, which result in catastrophic floods, are the powerful cloud systems that contain huge amount of water. According to the hypothesis argued in this paper, an electric field coupled with powerful clouds and electric forces play a cardinal role in supporting this huge mass of water at a high altitude in the troposphere and in the instability of powerful clouds sometimes during rather a long time duration. Based on this hypothesis, a highly effective method of volume electric charge neutralization of powerful clouds is proposed. It results in the decrease in an electric field, a sudden increase in precipitation, and subsequent degradation of powerful clouds. This method, based on the natural phenomenon, ensures the prevention of the intensification of tropical and extratropical cyclones and their transition to the storm and hurricane (typhoon stages, which makes it possible to avoid catastrophic floods. It also ensures the suppression of severe thunderclouds, which, in turn, eliminates the development of dangerous thunderstorms and the possibility of the emergence and intensification of tornadoes.

  20. Understanding the varied response of the extratropical storm tracks to climate change.

    Science.gov (United States)

    O'Gorman, Paul A

    2010-11-09

    Transient eddies in the extratropical storm tracks are a primary mechanism for the transport of momentum, energy, and water in the atmosphere, and as such are a major component of the climate system. Changes in the extratropical storm tracks under global warming would impact these transports, the ocean circulation and carbon cycle, and society through changing weather patterns. I show that the southern storm track intensifies in the multimodel mean of simulations of 21st century climate change, and that the seasonal cycle of storm-track intensity increases in amplitude in both hemispheres. I use observations of the present-day seasonal cycle to confirm the relationship between storm-track intensity and the mean available potential energy of the atmosphere, and show how this quantitative relationship can be used to account for much of the varied response in storm-track intensity to global warming, including substantially different responses in simulations with different climate models. The results suggest that storm-track intensity is not related in a simple way to global-mean surface temperature, so that, for example, a stronger southern storm track in response to present-day global warming does not imply it was also stronger in hothouse climates of the past.

  1. Utilization of satellite cloud information to diagnose the energy state and transformations in extratropical cyclones

    Science.gov (United States)

    Smith, P. J.

    1985-01-01

    An important component of the research was a continuing investigation of the impact of latent release on extratropical cyclone development. Previous efforts to accomplish this task have focused on the energy balance and the vertical motion field of an intense winter extratropical cyclone over the United States. During this fiscal year researchers turned their attention to a more fundamental diagnostic variable, the height tendency. Central to this effort is the use of a modified form of the quasi-geostrophic height tendency equation, in which geostrophic wind components have been replaced by observed winds and a latent heat release term has been added. This methodology was adopted to produce a simple diagnostic model which retains the essential mechanisms of quasi-geostrophic theory but more faithfully describes observed wave development when the Rossby Number approaches and exceeds 0.5. Results to date indicate that the new model yields height tendencies that are superior to those obtained from the quasi-geostrophic formulation and are sufficiently close to the observed tendencies to be a useful tool for diagnosing the principle large-scale forcing mechanisms in th e700-300 mb layer. Of the three forcing terms included in the new model, vortity advection is in general dominant. The most persistent challenge to this dominance is made by the thermal advection. On the whole, latent heat release plays a secondary role. Finally, during the rapid intensification observed for this cyclone, all three processes complement each other in forcing height falls.

  2. Atmospheric pressure variations at extratropical latitudes associated with Forbush decreases of galactic cosmic rays

    Science.gov (United States)

    Artamonova, I.; Veretenenko, S.

    2014-12-01

    Changes of troposphere pressure associated with short-time variations of galactic cosmic rays (GCRs) taking place in the Northern hemisphere's cold months (October-March) were analyzed for the period 1980-2006, NCEP/NCAR reanalysis data being used. Noticeable pressure variations during Forbush decreases of GCRs were revealed at extratropical latitudes of both hemispheres. The maxima of pressure increase were observed on the 3rd-4th days after the event onsets over Northern Europe and the European part of Russia in the Northern hemisphere, as well as on the 4th-5th days over the eastern part of the South Atlantic opposite Queen Maud Land and over the d'Urville Sea in the Southern Ocean. According to the weather chart analysis, the observed pressure growth, as a rule, results from the weakening of cyclones and intensification of anticyclone development in these areas. The presented results suggest that cosmic ray variations may influence the evolution of extratropical baric systems and play an important role in solar-terrestrial relationships.

  3. Extratropical Cyclogenesis and Frontal Waves on Mars: Influences on Dust, Weather and the Planet's climate

    Science.gov (United States)

    Hollingsworth, J. L.; Kahre, Melinda A.

    2012-01-01

    Between late autumn and early spring, middle and high latitudes on Mars exhibit strong equatortopole mean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic periodwaves) [1,2]. For a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, these large-scale, extratropical weather disturbances are critical components of the global circulation. The wavelike disturbances act as agents in the transport of heat and momentum between low and high latitudes of the planet. Through cyclonic/anticyclonic winds, intense shear deformations, contractions-dilatations in temperature and density, and sharp perturbations amongst atmospheric tracers (i.e., dust, volatiles (e.g., water vapor) and condensates (e.g., water-ice cloud particles)), Mars extratropical weather systems have significant subsynoptic scale ramifications by supporting atmospheric frontal waves (Fig. 1).

  4. Characteristic Paths of Extratropical Cyclones that Cause High Wind Events in the Northeast United States

    Science.gov (United States)

    Booth, J. F.; Rieder, H. E.; Lee, D.; Kushnir, Y.

    2014-12-01

    This study analyzes the association between wintertime high wind events (HWEs) in the northeast United States US and extratropical cyclones. Sustained wind maxima in the Daily Summary Data from the National Climatic Data Center's Integrated Surface Database are analyzed for 1979-2012. For each station, a Generalized Pareto Distribution (GPD) is fit to the upper tail of the daily maximum wind speed data, and probabilistic return levels at intervals of 1, 3 and 5-years are derived from the GPD fit. At each interval, wind events meeting the return level criteria are termed HWEs. The HWEs occurring on the same day are grouped into multi-station events allowing the association with extratropical cyclones, which are tracked in the European Center for Medium-Range Weather Forecast ERA-Interim reanalysis. Using hierarchical clustering analysis, this study finds that the HWEs are most often associated with cyclones travelling from southwest to northeast, usually originating west of the Appalachian Mountains. The results show that a storm approaching from the southwest is four times more likely to cause strong surface winds than a Nor'easter. A series of sensitivity analyses confirms the robustness of this result. Next, the relationship between the strength of the wind events and the corresponding storm minimum sea level pressure is analyzed. No robust relationship between these quantities is found for strong wind events. Nevertheless, subsequent analysis shows that a relationship between deeper storms and stronger winds emerges if the analysis is extended to the entire set of wintertime storms.

  5. A response in the ENSO cycle to an extratropical forcing mechanism during the El Niño to La Niña transition

    Directory of Open Access Journals (Sweden)

    Yafei Wang

    2013-12-01

    Full Text Available Current El Niño-Southern oscillation (ENSO theory emphasizes that the forcing that drives the cycle mainly exists within tropical regions. However, these ideas are quite limited in explaining completely the occurrence of ENSO. Here, we examine whether extratropical forcing can affect ENSO cycle, specifically the transition from El Niño to La Niña. Although dispersion of the Okhotsk-Japan (OKJ atmospheric wave train across the mid-latitude North Pacific during June terminates in the subtropics, the associated regime of southward surface wind anomalies could reach Eastern Equatorial Pacific (EEP. The OKJ wave train plays a substantial role in generating a similar underlying sea surface temperature (SST wave train through a barotropic process in air–sea interactions and after September, it is negatively correlated strongly with the SST around EEP. Strong OKJ propagation in the positive (negative phase during June is more (less significantly associated with a subsequent La Niña (El Niño episode that is matured after October. Negative SST anomalies at the southern end of the SST wave train with strong overlying OKJ propagation in the positive phase during June and the associated southward surface wind anomalies retained its strength by the further infusion of energy and gradual southward displacement joining the negative SST anomalies around EEP after the October when La Niña usually matured in-situ. Strong OKJ propagation in the positive phase during June tends to occur during a quick summer and fall transition period from El Niño to La Niña. This study strongly suggests that extratropical forcing plays an ignored role in affecting ENSO cycle especially in the formation of La Niña, which was not included in current ENSO theory.

  6. Radiative Energy Balance in the Tropical Tropopause Layer: An Investigation with ARM Data

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Qiang

    2013-10-22

    The overall objective of this project is to use the ARM observational data to improve our understanding of cloud-radiation effects in the tropical tropopause layer (TTL), which is crucial for improving the simulation and prediction of climate and climate change. In last four and half years, we have been concentrating on (i) performing the comparison of the ice cloud properties from the ground-based lidar observations with those from the satellite CALIPSO lidar observations at the ARM TWP sites; (ii) analyzing TTL cirrus and its relation to the tropical planetary waves; (iii) calculating the radiative heating rates using retrieved cloud microphysical properties by combining the ground-based lidar and radar observations at the ARM TWP sites and comparing the results with those using cloud properties retrieved from CloudSat and CALIPSO observations; (iv) comparing macrophysical properties of tropical cirrus clouds from the CALIPSO satellite and from ground-based micropulse and Raman lidar observations; (v) improving the parameterization of optical properties of cirrus clouds with small effective ice particle sizes; and (vi) evaluating the enhanced maximum warming in the tropical upper troposphere simulated by the GCMs. The main results of our research efforts are reported in the 12 referred journal publications that acknowledge the DOE Grant No. DE-FG02-09ER64769.

  7. Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL

    Directory of Open Access Journals (Sweden)

    F. Ploeger

    2010-10-01

    Full Text Available We explore the potential of ozone observations to constrain transport processes in the tropical tropopause layer (TTL, and contrast it with insights that can be obtained from water vapour. Global fields from Halogen Occultation Experiment (HALOE and in-situ observations are predicted using a backtrajectory approach that captures advection, instantaneous freeze-drying and photolytical ozone production. Two different representations of transport (kinematic and diabatic 3-month backtrajectories based on ERA-Interim data are used to evaluate the sensitivity to differences in transport. Results show that mean profiles and seasonality of both tracers can be reasonably reconstructed. Water vapour predictions are similar for both transport representations, but predictions for ozone are systematically higher for kinematic transport. While for global HALOE observations the diabatic prediction underestimates the vertical ozone gradient, for SCOUT-O3 in-situ observations the kinematic prediction shows a clear high bias above 390 K. We show that ozone predictions and vertical dispersion of the trajectories are highly correlated, rendering ozone an interesting tracer for aspects of transport to which water vapour is not sensitive. We show that dispersion and mean upwelling have similar effects on ozone profiles, with slower upwelling and larger dispersion both leading to higher ozone concentrations. Analyses of tropical upwelling based on mean transport characteristics, and model validation have to take into account this ambiguity. In turn, ozone may provide constraints on aspects of transport in the TTL and lower stratosphere that cannot be obtained from water vapour.

  8. Ice nucleation and cloud microphysical properties in tropical tropopause layer cirrus

    Directory of Open Access Journals (Sweden)

    E. J. Jensen

    2009-10-01

    Full Text Available In past modeling studies, it has generally been assumed that the predominant mechanism for nucleation of ice in the uppermost troposphere is homogeneous freezing of aqueous aerosols. However, recent in situ and remote-sensing measurements of the properties of cirrus clouds at very low temperatures in the tropical tropopause layer (TTL are broadly inconsistent with theoretial predictions based on the homogeneous freezing assumption. The nearly ubiquitous occurence of gravity waves in the TTL makes the predictions from homogeneous nucleation theory particularly difficult to reconcile with measurements. These measured properties include ice number concentrations, which are much lower than theory predicts; ice crystal size distributions, which are much broader than theory predicts; and cloud extinctions, which are much lower than theory predicts. Although other explanations are possible, one way to limit ice concentrations is to have on the order of 50 L−1 effective ice nuclei (IN that could nucleate ice at relatively low supersaturations. We suggest that ammonium sulfate particles, which would be dry much of the time in the cold TTL, are a potential IN candidate for TTL cirrus. Possible implications of the observed cloud microphysical properties for ice sedimentation, dehydration, and cloud persistence are also discussed.

  9. Ice nucleation and cloud microphysical properties in tropical tropopause layer cirrus

    Directory of Open Access Journals (Sweden)

    E. J. Jensen

    2010-02-01

    Full Text Available In past modeling studies, it has generally been assumed that the predominant mechanism for nucleation of ice in the uppermost troposphere is homogeneous freezing of aqueous aerosols. However, recent in situ and remote-sensing measurements of the properties of cirrus clouds at very low temperatures in the tropical tropopause layer (TTL are broadly inconsistent with theoretial predictions based on the homogeneous freezing assumption. The nearly ubiquitous occurence of gravity waves in the TTL makes the predictions from homogeneous nucleation theory particularly difficult to reconcile with measurements. These measured properties include ice number concentrations, which are much lower than theory predicts; ice crystal size distributions, which are much broader than theory predicts; and cloud extinctions, which are much lower than theory predicts. Although other explanations are possible, one way to limit ice concentrations is to have on the order of 50 L−1 effective ice nuclei (IN that could nucleate ice at relatively low supersaturations. We suggest that ammonium sulfate particles, which would be dry much of the time in the cold TTL, are a potential IN candidate for TTL cirrus. However, this mechanism remains to be fully quantified for the size distribution of ammonium sulfate (possibly internally mixed with organics actually present in the upper troposphere. Possible implications of the observed cloud microphysical properties for ice sedimentation, dehydration, and cloud persistence are also discussed.

  10. Nature, Origin, Potential Composition, and Climate Impact of the Asian Tropopause Aerosol Layer (ATAL)

    Science.gov (United States)

    Fairlie, T. D.; Vernier, J.-P.; Thomason, L. W.; Natarajan, M.; Bedka, K.; Wienhold, F.; Bian J.; Martinsson, B.

    2015-01-01

    Satellite observations from SAGE II and CALIPSO indicate that summertime aerosol extinction has more than doubled in the Asian Tropopause Aerosol Layer (ATAL) since the late 1990s. Here we show remote and in-situ observations, together with results from a chemical transport model (CTM), to explore the likely composition, origin, and radiative forcing of the ATAL. We show in-situ balloon measurements of aerosol backscatter, which support the high levels observed by CALIPSO since 2006. We also show in situ measurements from aircraft, which indicate a predominant carbonaceous contribution to the ATAL (Carbon/Sulfur ratios of 2- 10), which is supported by the CTM results. We show that the peak in ATAL aerosol lags by 1 month the peak in CO from MLS, associated with deep convection over Asia during the summer monsoon. This suggests that secondary formation and growth of aerosols in the upper troposphere on monthly timescales make a significant contribution to ATAL. Back trajectory calculations initialized from CALIPSO observations provide evidence that deep convection over India is a significant source for ATAL through the vertical transport of pollution to the upper troposphere.

  11. Clouds and the extratropical circulation response to global warming in a hierarchy of global atmosphere models

    Science.gov (United States)

    Voigt, Aiko

    2017-04-01

    Climate models project that global warming will lead to substantial changes in the position of the extratropical jet streams. Yet, many quantitative aspects of such jet stream changes remain uncertain among models, and recent work has indicated a potentially important role of cloud radiative interactions. Here, I will investigate how cloud-radiative changes impact the extratropical circulation response using a hierarchy of global atmosphere models. I will first focus on aquaplanet setups with prescribed sea-surface temperatures (SSTs), which reproduce the model spread found in realistic simulations with interactive SSTs. Simulations with two CMIP5 models MPI-ESM and IPSL-CM5A and prescribed clouds show that half of the circulation response can be attributed to cloud changes. The rise of tropical high-level clouds and the upward and poleward movement of midlatitude high-level clouds lead to poleward jet shifts. High-latitude low-level cloud changes shift the jet poleward in one model but not in the other. The impact of clouds on the jet operates via the atmospheric radiative forcing that is created by the cloud changes and is qualitatively reproduced in a dry Held-Suarez model, although the latter is too sensitive because of its simplified treatment of diabatic processes. I will then show that the aquaplanet results also hold when the models are used in a realistic setup that includes continents and seasonality. Finally, I will juxtapose these prescribed-SST simulations with interactive-SST simulations. This will allow for a comparison of the circulation impacts of atmospheric and surface cloud-radiative changes.

  12. Probing the subtropical lowermost stratosphere and the tropical upper troposphere and tropopause layer for inorganic bromine

    Science.gov (United States)

    Werner, Bodo; Stutz, Jochen; Spolaor, Max; Scalone, Lisa; Raecke, Rasmus; Festa, James; Fedele Colosimo, Santo; Cheung, Ross; Tsai, Catalina; Hossaini, Ryan; Chipperfield, Martyn P.; Taverna, Giorgio S.; Feng, Wuhu; Elkins, James W.; Fahey, David W.; Gao, Ru-Shan; Hintsa, Erik J.; Thornberry, Troy D.; Moore, Free Lee; Navarro, Maria A.; Atlas, Elliot; Daube, Bruce C.; Pittman, Jasna; Wofsy, Steve; Pfeilsticker, Klaus

    2017-01-01

    We report measurements of CH4 (measured in situ by the Harvard University Picarro Cavity Ringdown Spectrometer (HUPCRS) and NOAA Unmanned Aircraft System Chromatograph for Atmospheric Trace Species (UCATS) instruments), O3 (measured in situ by the NOAA dual-beam ultraviolet (UV) photometer), NO2, BrO (remotely detected by spectroscopic UV-visible (UV-vis) limb observations; see the companion paper of Stutz et al., 2016), and of some key brominated source gases in whole-air samples of the Global Hawk Whole Air Sampler (GWAS) instrument within the subtropical lowermost stratosphere (LS) and the tropical upper troposphere (UT) and tropopause layer (TTL). The measurements were performed within the framework of the NASA-ATTREX (National Aeronautics and Space Administration - Airborne Tropical Tropopause Experiment) project from aboard the Global Hawk (GH) during six deployments over the eastern Pacific in early 2013. These measurements are compared with TOMCAT/SLIMCAT (Toulouse Off-line Model of Chemistry And Transport/Single Layer Isentropic Model of Chemistry And Transport) 3-D model simulations, aiming at improvements of our understanding of the bromine budget and photochemistry in the LS, UT, and TTL.Changes in local O3 (and NO2 and BrO) due to transport processes are separated from photochemical processes in intercomparisons of measured and modeled CH4 and O3. After excellent agreement is achieved among measured and simulated CH4 and O3, measured and modeled [NO2] are found to closely agree with ≤ 15 ppt in the TTL (which is the detection limit) and within a typical range of 70 to 170 ppt in the subtropical LS during the daytime. Measured [BrO] ranges between 3 and 9 ppt in the subtropical LS. In the TTL, [BrO] reaches 0.5 ± 0.5 ppt at the bottom (150 hPa/355 K/14 km) and up to about 5 ppt at the top (70 hPa/425 K/18.5 km; see Fueglistaler et al., 2009 for the definition of the TTL used), in overall good agreement with the model simulations. Depending on the

  13. Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL

    Directory of Open Access Journals (Sweden)

    F. Ploeger

    2011-01-01

    Full Text Available We explore the potential of ozone observations to constrain transport processes in the tropical tropopause layer (TTL, and contrast it with insights that can be obtained from water vapour. Global fields from Halogen Occultation Experiment (HALOE and in-situ observations are predicted using a backtrajectory approach that captures advection, instantaneous freeze-drying and photolytical ozone production. Two different representations of transport (kinematic and diabatic 3-month backtrajectories based on ERA-Interim data are used to evaluate the sensitivity to differences in transport. Results show that mean profiles and seasonality of both tracers can be reasonably reconstructed. Water vapour predictions are similar for both transport representations, but predictions for ozone are systematically higher for kinematic transport. Compared to global HALOE observations, the diabatic model prediction underestimates the vertical ozone gradient. Comparison of the kinematic prediction with observations obtained during the tropical SCOUT-O3 campaign shows a large high bias above 390 K potential temperature. We show that ozone predictions and vertical dispersion of the trajectories are highly correlated, rendering ozone an interesting tracer for aspects of transport to which water vapour is not sensitive. We show that dispersion and mean upwelling have similar effects on ozone profiles, with slower upwelling and larger dispersion both leading to higher ozone concentrations. Analyses of tropical upwelling based on mean transport characteristics, and model validation have to take into account this ambiguity between tropical ozone production and in-mixing from the stratosphere. In turn, ozone provides constraints on transport in the TTL and lower stratosphere that cannot be obtained from water vapour.

  14. Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL)

    Science.gov (United States)

    Ploeger, F.; Fueglistaler, S.; Grooß, J.-U.; Günther, G.; Konopka, P.; Liu, Y. S.; Müller, R.; Ravegnani, F.; Schiller, C.; Ulanovski, A.; Riese, M.

    2011-01-01

    We explore the potential of ozone observations to constrain transport processes in the tropical tropopause layer (TTL), and contrast it with insights that can be obtained from water vapour. Global fields from Halogen Occultation Experiment (HALOE) and in-situ observations are predicted using a backtrajectory approach that captures advection, instantaneous freeze-drying and photolytical ozone production. Two different representations of transport (kinematic and diabatic 3-month backtrajectories based on ERA-Interim data) are used to evaluate the sensitivity to differences in transport. Results show that mean profiles and seasonality of both tracers can be reasonably reconstructed. Water vapour predictions are similar for both transport representations, but predictions for ozone are systematically higher for kinematic transport. Compared to global HALOE observations, the diabatic model prediction underestimates the vertical ozone gradient. Comparison of the kinematic prediction with observations obtained during the tropical SCOUT-O3 campaign shows a large high bias above 390 K potential temperature. We show that ozone predictions and vertical dispersion of the trajectories are highly correlated, rendering ozone an interesting tracer for aspects of transport to which water vapour is not sensitive. We show that dispersion and mean upwelling have similar effects on ozone profiles, with slower upwelling and larger dispersion both leading to higher ozone concentrations. Analyses of tropical upwelling based on mean transport characteristics, and model validation have to take into account this ambiguity between tropical ozone production and in-mixing from the stratosphere. In turn, ozone provides constraints on transport in the TTL and lower stratosphere that cannot be obtained from water vapour.

  15. The influence of solar wind on extratropical cyclones – Part 1: Wilcox effect revisited

    Directory of Open Access Journals (Sweden)

    M. Rybanský

    2009-01-01

    mean VAI response to SBP associated with the north-to-south reversal of BZ is leading by up to 2 days the mean VAI response to SBP associated with the south-to-north reversal of BZ. For the latter, less geoeffective events, the VAI minimum deepens (with the above exception of the Northern Hemisphere low-aerosol 500-mb VAI and the VAI maximum is delayed. The phase shift between the mean VAI responses obtained for these two subsets of SBP events may explain the reduced amplitude of the overall Wilcox effect. In a companion paper, Prikryl et al. (2009 propose a new mechanism to explain the Wilcox effect, namely that solar-wind-generated auroral atmospheric gravity waves (AGWs influence the growth of extratropical cyclones. It is also observed that severe extratropical storms, explosive cyclogenesis and significant sea level pressure deepenings of extratropical storms tend to occur within a few days of the arrival of high-speed solar wind. These observations are discussed in the context of the proposed AGW mechanism as well as the previously suggested atmospheric electrical current (AEC model (Tinsley et al., 1994, which requires the presence of stratospheric aerosols for a significant (Wilcox effect.

  16. New evidence and modeling studies of cross-tropopause transport of water substance by deep convective storms

    Science.gov (United States)

    Wang, P. K.

    2016-12-01

    Water vapor in the stratosphere can intercept substantial amount of terrestrial infrared radiation, thus causing exasperation of global warming at the surface due to increasing CO2. It also serves as the source material for making stratospheric odd hydrogen species that may cause ozone depletion through certain catalytic cycles. It is therefore very important to identify the process via which water vapor is transported across the tropopause into the stratosphere. Transport of water substance into the stratosphere by deep convective storms have been investigated by the author since around 2000, and in 2003 he proposed that it is the internal gravity wave breaking at the storm top that causes the water substance to penetrate through the tropopause and enter the stratosphere. Since then increasing evidence, including the observation of above-anvil cirrus plumes, jumping cirrus at the storm top, and the so-called pancake clouds, have been suggested as the manifestation of this wave breaking phenomenon. Cloud-resolving model studies did show the clear connection between these phenomena and wave breaking. Still there are several unresolved questions such as whether or not the jumping cirrus eventually evolves into plumes and whether the pancake clouds really exist. In this paper, I will show new aircraft and satellite observational evidence that confirm the above questions. These evidence demonstrate that the jumping cirrus can indeed evolve into plumes as observed by satellite storm images and that new rapid scan satellite storm images reveal the existence of the pancake clouds. New high resolution model simulations show cloud top features that match the observation very well and thus vindicating the role of gravity wave breaking in this process. Model results also give an estimate of the cross-tropopause transport of water substance that is much larger than previously thought.

  17. Traveling Weather Disturbances in Mars' Southern Extratropics: Sway of the Great Impact Basins

    Science.gov (United States)

    Hollingsworth, Jeffery L.

    2016-04-01

    As on Earth, between late autumn and early spring on Mars middle and high latitudes within its atmosphere support strong mean thermal contrasts between the equator and poles (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Within a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, such large-scale, extratropical weather disturbances are critical components of the global circulation. These wave-like disturbances act as agents in the transport of heat and momentum, and moreover generalized tracer quantities (e.g., atmospheric dust, water vapor and water-ice clouds) between low and high latitudes of the planet. The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a high-resolution Mars global climate model (Mars GCM). This global circulation model imposes interactively lifted (and radiatively active) dust based on a threshold value of the instantaneous surface stress. Compared to observations, the model exhibits a reasonable "dust cycle" (i.e., globally averaged, a more dusty atmosphere during southern spring and summer occurs). In contrast to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense synoptically. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather disturbances are examined. Simulations that adapt Mars' full topography compared to simulations that utilize synthetic topographies emulating essential large-scale features of the southern middle latitudes indicate that Mars

  18. The interannual leading modes of the extratropical variability in the Southern Hemisphere simulated by the ECHAM-4 atmospheric model

    Energy Technology Data Exchange (ETDEWEB)

    Carril, A.F. [ISAO, Istituto di Scienze dell' Atmosfera e dell' Oceano, Bologna (Italy); Navarra, A. [INGV, Istituto Nazionale di Geofisicae Vulcanologia, Rome (Italy)

    2001-11-01

    An ensemble of twenty-three 14-year experiments conducted with the ECHAM-4 GCM has been examined to test the model's capability to simulate the principal modes of interannual variability. The integrations were performed under specified monthly SST between 1979-1993. The analysis was focused on the Southern Hemisphere (SH) extratropics. Empirical orthogonal functions analysis (EOF) using seasonal anomaly fields has been performed to isolate the principal modes that dominate the southern extratropical variability at the interannual time scale. Leading patterns of 500 hPa geopotential height (z500) have been compared with those estimated from the ECMWF re-analysis dataset. The model is able to adequately reproduce the spatial pattern of the annular mode, but it represents the temporal variations of the oscillation less satisfactorily. The model simulation of the Pacific South American (PSA) pattern is better, both in the shape of the pattern and in the temporal evolution. To verify if the capability of the model to adequately simulate the temporal oscillation of the propagating patterns is related to the increased influence of the tropical external forcing, covarying SST-atmospheric modes have been identified by singular value decomposition (SVD). In winter (July-August-September, JAS) the tropical SST variability is highly correlated with the ENSO mode. In summer (January-February-March, JFM) the strength of the teleconnections is related to strong westerly anomalies, disrupted by a meridional out of phase relation near to South America. The large size of the ensemble was exploited by comparing the time-varying model spread and degrees of freedom of the simulated extratropical circulation. Results show that when the extratropical circulation has a few degrees of freedom, the reproducibility is relatively low and the ensemble is governed by a fairly robust zonally symmetric structure of dispersion. (orig.)

  19. WRF simulations of two extreme snowfall events associated with contrasting extratropical cyclones over the western and central Himalaya

    OpenAIRE

    2015-01-01

    © 2015. American Geophysical Union. All Rights Reserved. Two extreme snowfall events associated with extratropical cyclones, one interacting with the western and one with the central Himalaya, are simulated with the Weather Research and Forecasting (WRF) model over 8 days. One event in January 1999 was driven by a longwave trough over west Asia, with the cyclone becoming terrain-locked in the western Himalayan notch. Another event in March 2006 was driven by a trough further south and east, f...

  20. The role of the cold sector of extratropical cyclones in setting atmospheric mean state features of the Gulf Stream basin.

    Science.gov (United States)

    Vannière, Benoît; Czaja, Arnaud; Dacre, Helen; Woollings, Tim

    2016-04-01

    The mechanism by which the Gulf Stream SST front anchors a band of precipitation on its warm edge is still a matter of debate and little is known about how synoptic activity contributes to shape precipitation mean state pattern. In this talk, we introduce a new indicator for the cold sector of extratropical storms based on low-level PV. This indicator is used in ERA interim data to separate the cold sector contribution to precipitation and vertical wind from the contribution of the rest of the storm. We find that cold sector precipitation forms a band following the SST front closely. In contrast, the enhanced ascent on the warm edge of the front is set primarily by the warm sector and cannot be directly related to the precipitation band as proposed by previous studies. Numerical sensitivity experiments of an extratropical cyclone passing over different sets of SST further confirms that the anchoring effect of the SST front on precipitation comes exclusively from the cold sector. These results lead us to revisit the atmospheric boundary layer model proposed to describe air-sea interactions over the Gulf-Stream SST gradient. Finally, we explore the role of the cold sector convection in restoring baroclinicity in the wake of an extratropical cyclone.

  1. High resolution modelling results of the wind flow over Canary Islands during the meteorological situation of the extratropical storm Delta (28–30 November 2005

    Directory of Open Access Journals (Sweden)

    J. M. Baldasano

    2008-05-01

    Full Text Available On 28–29 November 2005 an extratropical storm affected the Canary Islands causing significant damage related to high average wind speeds and intense gusts over some islands of the archipelago. Delta was the twenty-sixth tropical or subtropical storm of the 2005 Atlantic hurricane season. It represents an unusual meteorological phenomenon for that region, and its impacts were underestimated by the different operational meteorological forecasts during the previous days of the arrival of the low near Canary Islands. The aim of this study is to reproduce the local effects of the flow that were observed over the Canary Islands during the travel of the Delta storm near the region using high-resolution mesoscale meteorological simulations. The Advanced Research Weather Research & Forecasting Model (WRF-ARW is applied at 9, 3 and 1 km horizontal resolution using ECMWF forecasts as initial and boundary conditions. The high-resolution simulation will outline the main features that contributed to the high wind speeds observed in the archipelago. Variations in vertical static stability, vertical windshear and the intense synoptic winds of the southwestern part of Delta with a warm core at 850 hPa were the main characteristics that contributed to the development and amplification of intense gravity waves while the large-scale flow interacted with the complex topography of the islands.

  2. Effects of melting ice sheets and orbital forcing on the early Holocene warming in extratropical Northern Hemisphere

    Science.gov (United States)

    zhang, yurui; Renssen, Hans; Seppä, Heikki

    2016-04-01

    The early Holocene is an important climatological period, as it marked the final transition from the last deglaciation to the relatively warm and stable Holocene. Previous studies have analyzed the influence of the demise of the ice sheets and other forcings on the climate system during the Holocene. However, the climate response to the forcings together with the internal feedbacks before 9 ka remains not fully comprehended. In this study, we therefore disentangle how these forcings contributed to climate change during the earliest part of Holocene (11.5-7 ka) by employing the LOVECLIM climate model for both equilibrium and transient experiments. The results of our equilibrium experiments for 11.5 ka reveal that the annual mean temperature at the onset of the Holocene was lower than in the preindustrial era over most of the extratropical Northern Hemisphere. The magnitude of this cooler climate varies regionally and this spatial pattern is suggested by the biologically based proxies as well. In eastern N America and NW Europe the temperatures were 2-5 °C lower than in the preindustrial era as the climate was strongly influenced by the cooling effects of the ice sheets at here. This cooling of the ice-sheet surface was caused both by the enhanced surface albedo and by the orography of the ice sheets. In contrast, in Alaska, temperatures in all seasons were 0.5-3 °C higher than in the control run primarily due to the orbitally induced positive insolation anomaly and the enhanced southerly winds which advected warm air from the South as a response to the high air pressure over the Laurentide Ice Sheet (LIS). Our transient experiments indicate that the Holocene temperature evolution and the early Holocene warming were also geographically heterogeneous. In Alaska, the climate is constantly cooling over the whole Holocene. In contrast, in N Canada, there was an overall warming during the early Holocene up to 1.88 °C ka-1 in summer as a consequence of the progressive

  3. Long-lived contrails and convective cirrus above the tropical tropopause

    Science.gov (United States)

    Schumann, Ulrich; Kiemle, Christoph; Schlager, Hans; Weigel, Ralf; Borrmann, Stephan; D'Amato, Francesco; Krämer, Martina; Matthey, Renaud; Protat, Alain; Voigt, Christiane; Volk, C. Michael

    2017-02-01

    This study has two objectives: (1) it characterizes contrails at very low temperatures and (2) it discusses convective cirrus in which the contrails occurred. (1) Long-lived contrails and cirrus from overshooting convection are investigated above the tropical tropopause at low temperatures down to -88 °C from measurements with the Russian high-altitude research aircraft M-55 Geophysica, as well as related observations during the SCOUT-O3 field experiment near Darwin, Australia, in 2005. A contrail was observed to persist below ice saturation at low temperatures and low turbulence in the stratosphere for nearly 1 h. The contrail occurred downwind of the decaying convective system Hector of 16 November 2005. The upper part of the contrail formed at 19 km altitude in the tropical lower stratosphere at ˜ 60 % relative humidity over ice at -82 °C. The ˜ 1 h lifetime is explained by engine water emissions, slightly enhanced humidity from Hector, low temperature, low turbulence, and possibly nitric acid hydrate formation. The long persistence suggests large contrail coverage in case of a potential future increase of air traffic in the lower stratosphere. (2) Cirrus observed above the strongly convective Hector cloud on 30 November 2005 was previously interpreted as cirrus from overshooting convection. Here we show that parts of the cirrus were caused by contrails or are mixtures of convective and contrail cirrus. The in situ data together with data from an upward-looking lidar on the German research aircraft Falcon, the CPOL radar near Darwin, and NOAA-AVHRR satellites provide a sufficiently complete picture to distinguish between contrail and convective cirrus parts. Plume positions are estimated based on measured or analyzed wind and parameterized wake vortex descent. Most of the non-volatile aerosol measured over Hector is traceable to aircraft emissions. Exhaust emission indices are derived from a self-match experiment of the Geophysica in the polar stratosphere

  4. GPS radio occultation with CHAMP and SAC-C: global monitoring of thermal tropopause parameters

    Directory of Open Access Journals (Sweden)

    T. Schmidt

    2005-01-01

    Full Text Available In this study the global lapse-rate tropopause (LRT pressure, temperature, potential temperature, and sharpness are discussed based on Global Positioning System (GPS radio occultations (RO from the German CHAMP (CHAllenging Minisatellite Payload and the U.S.-Argentinian SAC-C (Satelite de Aplicaciones Cientificas-C satellite missions. Results with respect to seasonal variations are compared with operational radiosonde data and ECMWF (European Centre for Medium-Range Weather Forecast operational analyses. Results on the tropical quasi-biennial oscillation (QBO are updated from an earlier study. CHAMP RO data are available continuously since May 2001 with on average 150 high resolution temperature profiles per day. SAC-C data are available for several periods in 2001 and 2002. In this study temperature data from CHAMP for the period May 2001-December 2004 and SAC-C data from August 2001-October 2001 and March 2002-November 2002 were used, respectively. The bias between GPS RO temperature profiles and radiosonde data was found to be less than 1.5K between 300 and 10hPa with a standard deviation of 2-3K. Between 200-20hPa the bias is even less than 0.5K (2K standard deviation. The mean deviations based on 167699 comparisons between CHAMP/SAC-C and ECMWF LRT parameters are (-2.1±37.1hPa for pressure and (0.1±4.2K for temperature. Comparisons of LRT pressure and temperature between CHAMP and nearby radiosondes (13230 resulted in (5.8±19.8hPa and (-0.1±3.3K, respectively. The comparisons between CHAMP/SAC-C and ECMWF show on average the largest differences in the vicinity of the jet streams with up to 700m in LRT altitude and 3K in LRT temperature, respectively. The CHAMP mission generates the first long-term RO data set. Other satellite missions will follow (GRACE, COSMIC, MetOp, TerraSAR-X, EQUARS generating together some thousand temperature profiles daily.

  5. Signals of El Niño Modoki in the tropical tropopause layer and stratosphere

    Directory of Open Access Journals (Sweden)

    F. Xie

    2012-06-01

    Full Text Available The effects of El Niño Modoki events on the tropical tropopause layer (TTL and on the stratosphere were investigated using European Center for Medium Range Weather Forecasting (ECMWF reanalysis data, oceanic El Niño indices, and general climate model outputs. El Niño Modoki events tend to depress convective activities in the western and eastern Pacific but enhance convective activities in the central and northern Pacific. Consequently, during El Niño Modoki events, negative water vapor anomalies occur in the western and eastern Pacific upper troposphere, whereas there are positive anomalies in the central and northern Pacific upper troposphere. The spatial patterns of the outgoing longwave radiation (OLR and upper tropospheric water vapor anomalies exhibit a tripolar form. The empirical orthogonal function (EOF analysis of the OLR and upper tropospheric water vapor anomalies reveals that canonical El Niño events are associated with the leading mode of the EOF, while El Niño Modoki events correspond to the second mode. The composite analysis based on ERA-interim data indicate that El Niño Modoki events have a reverse effect on middle-high latitudes stratosphere, as compared with the effect of typical El Niño events, i.e., the northern polar vortex is stronger and colder but the southern polar vortex is weaker and warmer during El Niño Modoki events. According to the simulation' results, we found that the reverse effect on the middle-high latitudes stratosphere is resulted from a complicated interaction between quasi-biennial oscillation (QBO signal of east phase and El Niño Modoki signal. This interaction is not a simply linear overlay of QBO signal and El Niño Modoki signal in the stratosphere, it is El Niño Modoki that leads to different tropospheric zonal wind anomalies with QBO forcing from that caused by typical El Niño, thus, the planetary wave propagation from troposphere to the stratosphere during El Niño Modoki events is

  6. Signals of El Niño Modoki in the tropical tropopause layer and stratosphere

    Directory of Open Access Journals (Sweden)

    F. Xie

    2012-02-01

    Full Text Available The effects of El Niño Modoki events on the tropical tropopause layer (TTL and on the stratosphere were investigated using European Center for Medium Range Weather Forecasting (ECMWF reanalysis data, satellite observations from the Aura satellite Microwave Limb Sounder (MLS, oceanic El Niño indices, and general climate model outputs. El Niño Modoki events tend to depress convective activities in the western and eastern Pacific but enhance convective activities in the central and northern Pacific. Consequently, during Modoki events, negative water vapor anomalies occur in the western and eastern Pacific upper troposphere, whereas there are positive anomalies in the central and northern Pacific upper troposphere. The spatial patterns of the outgoing longwave radiation (OLR and upper tropospheric water vapor anomalies exhibit a tripolar form. The empirical orthogonal function (EOF analysis of the OLR and upper tropospheric water vapor anomalies reveals that canonical El Niño events are associated with the leading mode of the EOF, while El Niño Modoki events correspond to the second mode. El Niño Modoki activities tend to moisten the lower and middle stratosphere, but dry the upper stratosphere. It was also found that the canonical El Niño signal can overlay linearly on the QBO signal in the stratosphere, whereas the interaction between the El Niño Modoki and QBO signals is non-linear. Because of these non-linear interactions, El Niño Modoki events have a reverse effect on high latitudes stratosphere, as compared with the effects of typical Modoki events, i.e. the northern polar vortex is stronger and colder but the southern polar vortex is weaker and warmer during El Niño Modoki events. However, simulations suggest that canonical El Niño and El Niño Modoki activities actually have the same influence on high latitudes stratosphere, in the absence of interactions between QBO and ENSO signals. The present results also reveal that canonical

  7. Partial Whitening SVD Analysis and its application to tropical-extratropical teleconnections

    Science.gov (United States)

    Swenson, Erik

    2014-05-01

    Various multivariate statistical methods have been established and proven useful for isolating relationships between datasets. Many popular linear methods are based on Singular Value Decomposition (SVD) and include Canonical Correlation Analysis (CCA), Maximum Covariance Analysis (MCA), and Redundancy Analysis (RDA). In this study, Partial Whitening SVD Analysis (PWSVD) is introduced as a new technique that maximizes the squared covariance between partially-whitened variables. Applied as a pre-filter, the partial whitening transformation acts to decorrelate and normalize individual variables to a fractional degree that is specified prior. Particular PWSVD solutions include a new and effective regularization for CCA as well a variance bias correction for MCA. Also, given some crude prior expectation of the signal-to-noise, asymmetric PWSVD solutions can provide significant benefit, and the full range of solutions bridges those of CCA, MCA and RDA. After deriving PWSVD, it is used to linearly relate precipitation in the tropical Pacific with Northern Hemisphere extratropical circulation during boreal winter, and solutions are contrasted with those of traditional methods. It is demonstrated that PWSVD produces a highly robust representation of the dominant teleconnections, namely ENSO and ENSO Modoki, or flavors of ENSO. Lastly, the practical use of PWSVD is encouraged for a range of applications.

  8. Objective determination of the extratropical transition of tropical cyclones in the Northern Hemisphere

    Directory of Open Access Journals (Sweden)

    Joshua Studholme

    2015-05-01

    Full Text Available Extratropical transition (ET has eluded objective identification since the realisation of its existence in the 1970s. Recent advances in numerical, computational models have provided data of higher resolution than previously available. In conjunction with this, an objective characterisation of the structure of a storm has now become widely accepted in the literature. Here we present a method of combining these two advances to provide an objective method for defining ET. The approach involves applying K-means clustering to isolate different life-cycle stages of cyclones and then analysing the progression through these stages. This methodology is then tested by applying it to five recent years from the European Centre of Medium-Range Weather Forecasting operational analyses. It is found that this method is able to determine the general characteristics for ET in the Northern Hemisphere. Between 2008 and 2012, 54% (±7, 32 of 59 of Northern Hemisphere tropical storms are estimated to undergo ET. There is great variability across basins and time of year. To fully capture all the instances of ET is necessary to introduce and characterise multiple pathways through transition. Only one of the three transition types needed has been previously well-studied. A brief description of the alternate types of transitions is given, along with illustrative storms, to assist with further study.

  9. Has influence of extratropical waves in modulating Indian summer monsoon rainfall (ISMR) increased?

    Indian Academy of Sciences (India)

    A K Srivastava; Somenath Dutta; S R Kshirsagar; Kavita Srivastava

    2014-04-01

    In the paper, influence of extratropical circulation features on Indian Summer Monsoon Rainfall (ISMR) is examined. Energetics of extra tropics, north of Indian subcontinent for deficient and nondeficient ISMR years, during two periods 1951–1978 and 1979–2005, are calculated and critically analyzed. It is observed that for the period 1951–1978, only two out of the 10 energetic parameters, viz., the zonal available potential energy (high) and conversion of zonal available potential with kinetic energy to eddy kinetic energy (low) differed significantly in JJA months of the deficient years from that of the nondeficient years. However, during the 1979–2005 period, as many as six out of the 10 energetic parameters, viz., eddy available potential energy, zonal available potential energy, eddy kinetic energy, generation of zonal available potential energy, conversion of zonal available potential energy to zonal kinetic energy and conversion of zonal kinetic energy to eddy kinetic energy differed significantly in JJA months of the deficient years from that of the nondeficient years. These results confirm growing influence of the transient stationary waves in deficient years after the climate shift year, 1979. Analysis of energetic parameters of the pre-monsoon season of the two periods also reveals similar results. This suggests that forcings apparently responsible for energetics in JJA months of the deficient years of the later period were present even before the advent of Indian summer monsoon season.

  10. The impact of the Asian summer monsoon on the composition of the extratropical lower stratosphere

    Science.gov (United States)

    Hoor, Peter; Müller, Stefan; Bozem, Heiko; Krause, Jens; Zahn, Andreas; Boenisch, Harald; Engel, Andreas; Vogel, Bärbel; Rolf, Christian; Ploeger, Felix; Krämer, Martina; Riese, Martin; Schlager, Hans

    2017-04-01

    We present tracer measurements from the German research aircraft HALO, which were obtained during the TACTS/ESMVal-project (Transport and Composition in the UT/LS and Earth System Model Validation) in September 2012 in the northern mid latitude lower stratosphere. We will focus on the distribution of CO, N2O and ozone in the extratropics between potential temperatures of 360 K and 410 K and their changes over the course of the campaign. Based on the distribution of N2O and CO, which constitute two tropospheric tracers of different lifetime one can quantify time scales of transport and chemical ageing of air masses. To account for mixing we analyze the distribution of CO relative to N2O. In geometrical coordinates we observed an increase of N2O and CO over a course of four weeks due to the increased impact of the monsoon system. When analyzing CO relative N2O to account for mixing we observe a decrease of the tropospheric fraction relative to N2O. These results are consistent with the fact that air in Asian monsoon anticyclone is trapped which allows for photochemical CO degradation. Based on the correlation of CO and N2O we estimate an upper limit for the degradation of CO relative to N2O of 30 days.

  11. The kinetic and available potential energy budget of a winter extratropical cyclone system

    Science.gov (United States)

    Smith, P. J.; Dare, P. M.

    1986-01-01

    The energy budget of an extratropical cyclone system which traversed North America and intensified through the period January 9-11, 1975 is presented. The objectives of the study are: (1) to document the complete energy budget of a significant winter cyclone event, and (2) to comment on the significance of latent heat release (LHR) in the cyclone's evolution. Results reveal an overall increase in both kinetic (K) and available potential energy (A). K increases are accounted for by boundary flux convergence of K, while A increases are due to generation by LHR and K to A conversion. In addition, the general A increase is accompanied by a 24 h oscillation that is explained largely by the flux quantity in the A budget equation and is correlated with a similar fluctuation in the K to A conversion. LHR does not appear to be critical in the development of this cyclone system. Rather, LHR acts to increase the intensity of the event. It is hypothesized that the direct influence that LHR had on the deepening cyclone's reduced mass was augmented by an indirect influence, in which pre-existing dry dynamical forcing was enhanced by diabatic heating, thus leading to accelerated cyclone development at a later time.

  12. A Dynamic Analysis and Numerical Simulation of Explosive Development of an Extratropical Cyclone Over Land

    Institute of Scientific and Technical Information of China (English)

    丁一汇; 朱彤

    1994-01-01

    The present paper has made a dynamic and diagnostic study of the process of explosive deepening of an extratropical cyclone over North China on April 25-26, 1983, in order to gain an insight into the physical mechanism of explosive development of cyclone over land. It turns out that this cyclone occurred in the strong baroclinic zone, and the vorticity and thermal advection triggered the initial development of the cyclone. Subsequently, as the rainfall increased, the effect of condensational heating became more and more important. During the time period of rapid intensification (from 1200GMT 25 to 0000GMT 26 April, 1983, the central surface pressure fell down from 998. 2 to 988. 3 hPa), the peak of diabatic heating profile continuously descended, leading to a rapid increase in heating amount in the lower troposphere. This condition is favorable to the explosive development of rotational circulation or vortex. The numerical simulations have further demonstrated the importance of the lowering of heating p

  13. The kinetic and available potential energy budget of a winter extratropical cyclone system

    Science.gov (United States)

    Smith, P. J.; Dare, P. M.

    1986-01-01

    The energy budget of an extratropical cyclone system which traversed North America and intensified through the period January 9-11, 1975 is presented. The objectives of the study are: (1) to document the complete energy budget of a significant winter cyclone event, and (2) to comment on the significance of latent heat release (LHR) in the cyclone's evolution. Results reveal an overall increase in both kinetic (K) and available potential energy (A). K increases are accounted for by boundary flux convergence of K, while A increases are due to generation by LHR and K to A conversion. In addition, the general A increase is accompanied by a 24 h oscillation that is explained largely by the flux quantity in the A budget equation and is correlated with a similar fluctuation in the K to A conversion. LHR does not appear to be critical in the development of this cyclone system. Rather, LHR acts to increase the intensity of the event. It is hypothesized that the direct influence that LHR had on the deepening cyclone's reduced mass was augmented by an indirect influence, in which pre-existing dry dynamical forcing was enhanced by diabatic heating, thus leading to accelerated cyclone development at a later time.

  14. Mixing in the Extratropical Stratosphere: Model-measurements Comparisons using MLM Diagnostics

    Science.gov (United States)

    Ma, Jun; Waugh, Darryn W.; Douglass, Anne R.; Kawa, Stephan R.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    We evaluate transport processes in the extratropical lower stratosphere for both models and measurements with the help of equivalent length diagnostic from the modified Lagrangian-mean (MLM) analysis. This diagnostic is used to compare measurements of long-lived tracers made by the Cryogenic Limb Array Etalon Spectrometer (CLAES) on the Upper Atmosphere Research Satellite (UARS) with simulated tracers. Simulations are produced in Chemical and Transport Models (CTMs), in which meteorological fields are taken from the Goddard Earth Observing System Data Assimilation System (GEOS DAS), the Middle Atmosphere Community Climate Model (MACCM2), and the Geophysical Fluid Dynamics Laboratory (GFDL) "SKYHI" model, respectively. Time series of isentropic equivalent length show that these models are able to capture major mixing and transport properties observed by CLAES, such as the formation and destruction of polar barriers, the presence of surf zones in both hemispheres. Differences between each model simulation and the observation are examined in light of model performance. Among these differences, only the simulation driven by GEOS DAS shows one case of the "top-down" destruction of the Antarctic polar vortex, as observed in the CLAES data. Additional experiments of isentropic advection of artificial tracer by GEOS DAS winds suggest that diabatic movement might have considerable contribution to the equivalent length field in the 3D CTM diagnostics.

  15. Southern Hemisphere Additional Ozonesondes (SHADOZ) Ozone Climatology (2005-2009): Tropospheric and Tropical Tropopause Layer (TTL) Profiles with Comparisons to Omi-based Ozone Products

    Science.gov (United States)

    Thompson, Anne M.; Miller, Sonya K.; Tilmes, Simone; Kollonige, Debra W.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Johnson, Brian J.; Fujiwara, Masatomo; Schmidlin, F. J.; Coetzee, G. J. R.; Komala, Ninong; Maata, Matakite; bt Mohammad, Maznorizan; Nguyo, J.; Mutai, C.; Ogino, S-Y; Da Silva, F. Raimundo; Paes Leme, N. M.; Posny, Francoise; Scheele, Rinus; Selkirk, Henry B.; Shiotani, Masato; Stubi, Rene; Levrat, Gilbert; Calpini, Bertrand; Thouret, Valerie; Tsuruta, Haruo; Canossa, Jessica Valverde; Voemel, Holger; Yonemura, S.; Andres Diaz, Jorge; Tan Thanh, Nguyen T.; Thuy Ha, Hoang T.

    2012-01-01

    We present a regional and seasonal climatology of SHADOZ ozone profiles in the troposphere and tropical tropopause layer (TTL) based on measurements taken during the first five years of Aura, 2005-2009, when new stations joined the network at Hanoi, Vietnam; Hilo, Hawaii; Alajuela Heredia, Costa Rica; Cotonou, Benin. In all, 15 stations operated during that period. A west-to-east progression of decreasing convective influence and increasing pollution leads to distinct tropospheric ozone profiles in three regions: (1) western Pacific eastern Indian Ocean; (2) equatorial Americas (San Cristobal, Alajuela, Paramaribo); (3) Atlantic and Africa. Comparisons in total ozone column from soundings, the Ozone Monitoring Instrument (OMI, on Aura, 2004-) satellite and ground-based instrumentation are presented. Most stations show better agreement with OMI than they did for EPTOMS comparisons (1998-2004; Earth-ProbeTotal Ozone Mapping Spectrometer), partly due to a revised above-burst ozone climatology. Possible station biases in the stratospheric segment of the ozone measurement noted in the first 7 years of SHADOZ ozone profiles are re-examined. High stratospheric bias observed during the TOMS period appears to persist at one station. Comparisons of SHADOZ tropospheric ozone and the daily Trajectory-enhanced Tropospheric Ozone Residual (TTOR) product (based on OMIMLS) show that the satellite-derived column amount averages 25 low. Correlations between TTOR and the SHADOZ sondes are quite good (typical r2 0.5-0.8), however, which may account for why some published residual-based OMI products capture tropospheric interannual variability fairly realistically. On the other hand, no clear explanations emerge for why TTOR-sonde discrepancies vary over a wide range at most SHADOZ sites.

  16. The transition from the tropical to the extra-tropical ozone-QBO signature in EMAC-ESCiMo, ERA interim and ozone CCI data

    Science.gov (United States)

    Kerzenmacher, Tobias; Joeckel, Patrick; Braesicke, Peter

    2016-04-01

    The quasi-biennial oscillation (QBO) in the tropical zonal mean stratospheric winds is a major driver of interannual ozone variability in the tropics. The associated ozone variability is clearly seen in the tropics. In addition, it affects the interannual ozone variability in sub-tropical and mid-latitude regions. The QBO influence on ozone in all latitudes can be diagnosed in climate model data (free running or nudged EMAC simulations from the ESCiMo project), reanalysis data (ERA-Interim) and satellite data (ozone CCI). We extract the ozone-QBO signature from the data by using a Fourier filtering technique so that the modelled and observed structures can be compared. Starting from the signal in total column ozone, we construct composite latitude height cross-sections of ozone to reveal the vertical structure of QBO related changes for different phases of the ozone-QBO. We discuss the differences between the modelled (EMAC) and observed (CCI) signatures and compare them to ERA-Interim (a data assimilation system). With this diagnostic we improve our understanding of the physical mechanisms that contribute to ozone variability and how an `ozone change signal' can migrate from the tropics to the extra-tropics. Understanding the main mechanisms involved in this signal transfer lays the foundation for an improved trend detection on decadal time scales.

  17. A Comparison of Precipitation Distribution of Two Landfalling Tropical Cyclones during the Extratropical Transition

    Institute of Scientific and Technical Information of China (English)

    CHEN Guanghua

    2011-01-01

    The precipitation distributions associated with two landfalling tropical cyclones (TCs) during extratropical transition (ET) were examined in this study.Their distinction is that the bulk of precipitation fell to the left of the TC track in one TC and to the right in the other.The analyses indicate that,for the TC Haima (2004) case,accompanied by the approach of a deep midlatitude trough throughout the depth of the troposphere,the warm and moist air advection by the southeasterly flow north of TC was favorable for warm advection and frontogenesis to the northwest of the TC.Due to the steepening of equivalent potential temperature (θe),the air-parcel uplift along the θe surface,in collaboration with thermally direct circulation related to frontogenesis,led to enhanced precipitation northwest of the TC.In contrast,for TC Matsa (2005)embedded within a moister environment,a weak midlatitude trough was situated at the mid-upper level.The convection was triggered by the conditional instability at the lower level and then sustained by dynamic forcing at the mid-upper level so that the heavy precipitation occurred to the northeast of TC.For the two TC cases,the precipitation enhancement was also linked to the upper-level anomalous divergence associated with the jet-related forcing on the right side of the jet entrance.From the quasigeostrophic perspective,the advection of geostrophic absolute vorticity by the thermal wind most likely served as an indication reflecting the displacement of the vertical motion relative to the center of the TC.

  18. Using data assimilation to study extratropical Northern Hemisphere climate over the last millennium

    Directory of Open Access Journals (Sweden)

    M. Widmann

    2009-09-01

    Full Text Available Climate proxy data provide noisy, and spatially incomplete information on some aspects of past climate states, whereas palaeosimulations with climate models provide global, multi-variable states, which may however differ from the true states due to unpredictable internal variability not related to climate forcings, as well as due to model deficiencies. Using data assimilation for combining the empirical information from proxy data with the physical understanding of the climate system represented by the equations in a climate model is in principle a promising way to obtain better estimates for the climate of the past.

    Data assimilation has been used for a long time in weather forecasting and atmospheric analyses to control the states in atmospheric General Circulation Models such that they are in agreement with observation from surface, upper air, and satellite measurements. Here we discuss the similarities and the differences between the data assimilation problem in palaeoclimatology and in weather forecasting, and present and conceptually compare three data assimilation methods that have been developed in recent years for applications in palaeoclimatology. All three methods (selection of ensemble members, Forcing Singular Vectors, and Pattern Nudging are illustrated by examples that are related to climate variability over the extratropical Northern Hemisphere during the last millennium. In particular it is shown that all three methods suggest that the cold period over Scandinavia during 1790–1820 is linked to anomalous northerly or easterly atmospheric flow, which in turn is related to a pressure anomaly that resembles a negative state of the Northern Annular Mode.

  19. Using data assimilation to study extratropical Northern Hemisphere climate over the last millennium

    Directory of Open Access Journals (Sweden)

    M. Widmann

    2010-09-01

    Full Text Available Climate proxy data provide noisy, and spatially incomplete information on some aspects of past climate states, whereas palaeosimulations with climate models provide global, multi-variable states, which may however differ from the true states due to unpredictable internal variability not related to climate forcings, as well as due to model deficiencies. Using data assimilation for combining the empirical information from proxy data with the physical understanding of the climate system represented by the equations in a climate model is in principle a promising way to obtain better estimates for the climate of the past.

    Data assimilation has been used for a long time in weather forecasting and atmospheric analyses to control the states in atmospheric General Circulation Models such that they are in agreement with observation from surface, upper air, and satellite measurements. Here we discuss the similarities and the differences between the data assimilation problem in palaeoclimatology and in weather forecasting, and present and conceptually compare three data assimilation methods that have been developed in recent years for applications in palaeoclimatology. All three methods (selection of ensemble members, Forcing Singular Vectors, and Pattern Nudging are illustrated by examples that are related to climate variability over the extratropical Northern Hemisphere during the last millennium. In particular it is shown that all three methods suggest that the cold period over Scandinavia during 1790–1820 is linked to anomalous northerly or easterly atmospheric flow, which in turn is related to a pressure anomaly that resembles a negative state of the Northern Annular Mode.

  20. Extratropical Weather Systems on Mars: Radiatively-Active Water Ice Effects

    Science.gov (United States)

    Hollingsworth, J. L.; Kahre, M. A.; Haberle, R. M.; Urata, R. A.; Montmessin, F.

    2017-01-01

    Extratropical, large-scale weather disturbances, namely transient, synoptic-period,baroclinic barotropic eddies - or - low- (high-) pressure cyclones (anticyclones), are components fundamental to global circulation patterns for rapidly rotating, differentially heated, shallow atmospheres such as Earth and Mars. Such "wave-like" disturbances that arise via (geophysical) fluid shear instability develop, mature and decay, and travel west-to-east in the middle and high latitudes within terrestrial-like planetary atmospheres. These disturbances serve as critical agents in the transport of heat and momentum between low and high latitudes of the planet. Moreover, they transport trace species within the atmosphere (e.g., water vapor/ice, other aerosols (dust), chemical species, etc). Between early autumn through early spring, middle and high latitudes on Mars exhibit strong equator-to-pole mean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that such strong baroclinicity supports vigorous, large-scale eastward traveling weather systems [Banfield et al., 2004; Barnes et al., 1993]. A good example of traveling weather systems, frontal wave activity and sequestered dust activity from MGS/MOC image analyses is provided in Figure 1 (cf. Wang et al. [2005]). Utilizing an upgraded and evolving version of the NASA Ames Research Center (ARC) Mars global climate model, investigated here are key dynamical and physical aspects of simulated northern hemisphere (NH) large-scale extratropica lweather systems,with and without radiatively-active water ice clouds. Mars Climate Model:

  1. The influence of extratropical cloud phase and amount feedbacks on climate sensitivity

    Science.gov (United States)

    Frey, William R.; Kay, Jennifer E.

    2017-07-01

    Global coupled climate models have large long-standing cloud and radiation biases, calling into question their ability to simulate climate and climate change. This study assesses the impact of reducing shortwave radiation biases on climate sensitivity within the Community Earth System Model (CESM). The model is modified by increasing supercooled cloud liquid to better match absorbed shortwave radiation observations over the Southern Ocean while tuning to reduce a compensating tropical shortwave bias. With a thermodynamic mixed-layer ocean, equilibrium warming in response to doubled CO2 increases from 4.1 K in the control to 5.6 K in the modified model. This 1.5 K increase in equilibrium climate sensitivity is caused by changes in two extratropical shortwave cloud feedbacks. First, reduced conversion of cloud ice to liquid at high southern latitudes decreases the magnitude of a negative cloud phase feedback. Second, warming is amplified in the mid-latitudes by a larger positive shortwave cloud feedback. The positive cloud feedback, usually associated with the subtropics, arises when sea surface warming increases the moisture gradient between the boundary layer and free troposphere. The increased moisture gradient enhances the effectiveness of mixing to dry the boundary layer, which decreases cloud amount and optical depth. When a full-depth ocean with dynamics and thermodynamics is included, ocean heat uptake preferentially cools the mid-latitude Southern Ocean, partially inhibiting the positive cloud feedback and slowing warming. Overall, the results highlight strong connections between Southern Ocean mixed-phase cloud partitioning, cloud feedbacks, and ocean heat uptake in a climate forced by greenhouse gas changes.

  2. The relevance of individual microphysical processes for potential vorticity anomalies in extratropical cyclones

    Science.gov (United States)

    Crezee, Bas; Joos, Hanna; Wernli, Heini

    2016-04-01

    Extratropical cyclones have a large impact on daily weather through their accompanying strong winds and precipitation. The latent heating and cooling associated with microphysical processes like condensation, freezing and melting, sublimation and evaporation leads to the formation of distinct cloud diabatic potential vorticity (CDPV) anomalies. Positive low-level CDPV anomalies - which typically are formed along the fronts and close to the cyclone center - have been shown to interact with upper-level PV anomalies thereby potentially enhancing storm intensification. Here a novel method is applied, which calculates backward trajectories from the mature storm stage, integrates cloud diabatic PV changes due to microphysical processes, and constructs a CDPV budget for each individual anomaly. Thereby we quantify the contributions of, e.g., cloud condensation, depositional growth of snow and melting of snow to the individual anomalies and in turn to the near-surface circulation. First, we apply this method to an idealized mid-latitude cyclone. The formation of the relatively small low-level negative CDPV anomalies is dominated each by one specific process, depending on their location relative to the front. For the large positive PV anomaly we find that the strongest contributions are from in-cloud condensation and below-cloud snow melting and rain evaporation. Although contributions of in-cloud depositional growth of ice are rather small, they cover a very large area and are therefore dynamically significant, i.e., they produce a fairly large-scale but low-amplitude anomaly. In addition the results from the idealized simulations are compared to a wintertime cyclone. It will be discussed how well the method works for real cyclones and how closely the results agree with those from the idealized channel model experiment.

  3. Which way will the circulation shift in a changing climate? Possible nonlinearity of extratropical cloud feedbacks

    Science.gov (United States)

    Tandon, Neil F.; Cane, Mark A.

    2017-06-01

    In a suite of idealized experiments with the Community Atmospheric Model version 3 coupled to a slab ocean, we show that the atmospheric circulation response to CO2 increase is sensitive to extratropical cloud feedback that is potentially nonlinear. Doubling CO2 produces a poleward shift of the Southern Hemisphere (SH) midlatitude jet that is driven primarily by cloud shortwave feedback and modulated by ice albedo feedback, in agreement with earlier studies. More surprisingly, for CO2 increases smaller than 25 %, the SH jet shifts equatorward. Nonlinearities are also apparent in the Northern Hemisphere, but with less zonal symmetry. Baroclinic instability theory and climate feedback analysis suggest that as the CO2 forcing amplitude is reduced, there is a transition from a regime in which cloud and circulation changes are largely decoupled to a regime in which they are highly coupled. In the dynamically coupled regime, there is an apparent cancellation between cloud feedback due to warming and cloud feedback due to the shifting jet, and this allows the ice albedo feedback to dominate in the high latitudes. The extent to which dynamical coupling effects exceed thermodynamic forcing effects is strongly influenced by cloud microphysics: an alternate model configuration with slightly increased cloud liquid (LIQ) produces poleward jet shifts regardless of the amplitude of CO2 forcing. Altering the cloud microphysics also produces substantial spread in the circulation response to CO2 doubling: the LIQ configuration produces a poleward SH jet shift approximately twice that produced under the default configuration. Analysis of large ensembles of the Canadian Earth System Model version 2 demonstrates that nonlinear, cloud-coupled jet shifts are also possible in comprehensive models. We still expect a poleward trend in SH jet latitude for timescales on which CO2 increases by more than 25 %. But on shorter timescales, our results give good reason to expect significant

  4. Scavenging of biomass burning refractory black carbon and ice nuclei in a Western Pacific extratropical storm

    Directory of Open Access Journals (Sweden)

    J. L. Stith

    2011-01-01

    Full Text Available In situ airborne sampling of refractory black carbon (rBC particles and Ice Nuclei (IN was conducted in and near an extratropical cyclonic storm in the Western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Cloud hydrometeors were evaporated by a counterflow virtual impactor and the residue was sampled by a single particle soot photometer (SP2 instrument and a continuous flow diffusion chamber ice nucleus detector. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. In storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here −24 to −29 °C, IN measurements from ice particle residues generally agreed well with simultaneous measurements of total ice concentrations provided that the measurements were made at ambient temperatures similar to those in the CFDC chamber, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures (−22 to −6.4 °C, ice particle concentrations were similar to IN concentrations at CFDC chamber temperatures representative of colder temperatures. This is consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by sedimentation to lower altitudes. Homogeneous freezing did not appear to contribute significantly to midlevel ice concentrations and rime-splintering was also unlikely due to the absence of significant supercooled liquid water in the warm sector clouds. IN number concentrations were typically about a~factor of five to ten lower than simultaneous measurements of rBC concentrations in cloud.

  5. Effects of melting ice sheets and orbital forcing on the early Holocene warming in extratropical Northern Hemisphere

    Science.gov (United States)

    Zhang, Y.; Renssen, H.; Seppä, H.

    2015-11-01

    The early Holocene is a critical period for climate change, as it marked the final transition from the last deglaciation to the relatively warm and stable Holocene. It is characterized by a warming trend that has been registered in numerous proxy records. This climatic warming was accompanied by major adjustments in different climate components, including the decaying of ice sheets in cryosphere, the perturbation of circulation in the ocean, the expansion of vegetation (over the high latitude) in biosphere. Previous studies have analyzed the influence of the demise of the ice sheets and other forcings on climate system. However, the climate response to the forcings together with the internal feedbacks before 9 ka remains not fully comprehended. In this study, we therefore disentangle how these forcings contributed to climate change during the earliest part of Holocene (11.5-7 ka) by employing the LOVECLIM climate model for both equilibrium and transient experiments. The results of our equilibrium experiments for 11.5 ka reveal that the annual mean temperature at the onset of the Holocene was lower than in the preindustrial era in the Northern extratropics, except in Alaska. The magnitude of this cool anomaly varies regionally as a response to varying climate forcings and diverse mechanisms. In eastern N America and NW Europe the temperatures throughout the whole year were 2-5 °C lower than in the preindustrial control, reaching the maximum cooling as here the climate was strongly influenced by the cooling effects of the ice sheets. This cooling of the ice-sheet surface was caused both by the enhanced surface albedo and by the orography of the ice sheets. For Siberia, a small deviation (-0.5-1.5 °C) in summer temperature and 0.5-1.5 °C cooler annual climate compared to the preindustrial run were caused by the counteraction of the high albedo associated with the tundra vegetation which was more southward extended at 11.5 ka than in the preindustrial period and the

  6. The Observed Relationship Between Water Vapor and Ozone in the Tropical Tropopause Saturation Layer and the Influence of Meridional Transport

    Science.gov (United States)

    Selkirk, Henry B.; Schoeberl, M. R.; Olsen, M. A.; Douglass, A. R.

    2011-01-01

    We examine balloonsonde observations of water vapor and ozone from three Ticosonde campaigns over San Jose, Costa Rica [10 N, 84 W] during northern summer and a fourth during northern winter. The data from the summer campaigns show that the uppermost portion of the tropical tropopause layer between 360 and 380 K, which we term the tropopause saturation layer or TSL, is characterized by water vapor mixing ratios from proximately 3 to 15 ppmv and ozone from approximately 50 ppbv to 250 ppbv. In contrast, the atmospheric water vapor tape recorder at 380 K and above displays a more restricted 4-7 ppmv range in water vapor mixing ratio. From this perspective, most of the parcels in the TSL fall into two classes - those that need only additional radiative heating to rise into the tape recorder and those requiring some combination of additional dehydration and mixing with drier air. A substantial fraction of the latter class have ozone mixing ratios greater than 150 ppbv, and with water vapor greater than 7 ppmv this air may well have been transported into the tropics from the middle latitudes in conjunction with high-amplitude equatorial waves. We examine this possibility with both trajectory analysis and transport diagnostics based on HIRDLS ozone data. We apply the same approach to study the winter season. Here a very different regime obtains as the ozone-water vapor scatter diagram of the sonde data shows the stratosphere and troposphere to be clearly demarcated with little evidence of mixing in of middle latitude air parcels.

  7. Modeling the inorganic bromine partitioning in the tropical tropopause layer over the eastern and western Pacific Ocean

    Directory of Open Access Journals (Sweden)

    M. A. Navarro

    2017-08-01

    Full Text Available The stratospheric inorganic bromine (Bry burden arising from the degradation of brominated very short-lived organic substances (VSLorg and its partitioning between reactive and reservoir species is needed for a comprehensive assessment of the ozone depletion potential of brominated trace gases. Here we present modeled inorganic bromine abundances over the Pacific tropical tropopause based on aircraft observations of VSLorg from two campaigns of the Airborne Tropical TRopopause EXperiment (ATTREX 2013, carried out over the eastern Pacific, and ATTREX 2014, carried out over the western Pacific and chemistry-climate simulations (along ATTREX flight tracks using the specific meteorology prevailing. Using the Community Atmosphere Model with Chemistry (CAM-Chem we model that BrO and Br are the daytime dominant species. Integrated across all ATTREX flights, BrO represents ∼ 43 and 48 % of daytime Bry abundance at 17 km over the western and eastern Pacific, respectively. The results also show zones where Br / BrO > 1 depending on the solar zenith angle (SZA, ozone concentration, and temperature. On the other hand, BrCl and BrONO2 were found to be the dominant nighttime species with ∼  61 and 56 % of abundance at 17 km over the western and eastern Pacific, respectively. The western-to-eastern differences in the partitioning of inorganic bromine are explained by different abundances of ozone (O3, nitrogen dioxide (NO2, total inorganic chlorine (Cly, and the efficiency of heterogeneous reactions of bromine reservoirs (mostly BrONO2 and HBr occurring on ice crystals.

  8. Modeling the inorganic bromine partitioning in the tropical tropopause layer over the eastern and western Pacific Ocean

    Science.gov (United States)

    Navarro, Maria A.; Saiz-Lopez, Alfonso; Cuevas, Carlos A.; Fernandez, Rafael P.; Atlas, Elliot; Rodriguez-Lloveras, Xavier; Kinnison, Douglas; Lamarque, Jean-Francois; Tilmes, Simone; Thornberry, Troy; Rollins, Andrew; Elkins, James W.; Hintsa, Eric J.; Moore, Fred L.

    2017-08-01

    The stratospheric inorganic bromine (Bry) burden arising from the degradation of brominated very short-lived organic substances (VSLorg) and its partitioning between reactive and reservoir species is needed for a comprehensive assessment of the ozone depletion potential of brominated trace gases. Here we present modeled inorganic bromine abundances over the Pacific tropical tropopause based on aircraft observations of VSLorg from two campaigns of the Airborne Tropical TRopopause EXperiment (ATTREX 2013, carried out over the eastern Pacific, and ATTREX 2014, carried out over the western Pacific) and chemistry-climate simulations (along ATTREX flight tracks) using the specific meteorology prevailing. Using the Community Atmosphere Model with Chemistry (CAM-Chem) we model that BrO and Br are the daytime dominant species. Integrated across all ATTREX flights, BrO represents ˜ 43 and 48 % of daytime Bry abundance at 17 km over the western and eastern Pacific, respectively. The results also show zones where Br / BrO > 1 depending on the solar zenith angle (SZA), ozone concentration, and temperature. On the other hand, BrCl and BrONO2 were found to be the dominant nighttime species with ˜ 61 and 56 % of abundance at 17 km over the western and eastern Pacific, respectively. The western-to-eastern differences in the partitioning of inorganic bromine are explained by different abundances of ozone (O3), nitrogen dioxide (NO2), total inorganic chlorine (Cly), and the efficiency of heterogeneous reactions of bromine reservoirs (mostly BrONO2 and HBr) occurring on ice crystals.

  9. Studying temperature and dynamical variations in the extratropical boreal atmosphere in the 2012-2013 winter

    Science.gov (United States)

    Vargin, Pavel; Medvedeva, Irina

    A major Sudden Stratospheric Warming (SSW) event in early January 2013 led to a large increase in the polar stratospheric temperature (up to 60 K at 44 km height), zonal circulation reversal, split of the stratospheric polar vortex (wavenumber 2 type of SSW), and effected temperature and dynamics of the mesosphere - lower thermosphere. We analyzed the SSW-related variations in thermo-dynamical parameters of the atmosphere within a height range from the troposphere to the lower thermosphere, using reanalysis data and data of ground-based spectrometric and satellite observations. Wave activity in the extratropical troposphere and stratosphere was studied using calculated three-day means of the three-dimensional Plumb fluxes. We revealed amplification in activity of planetary waves propagating from the troposphere to the stratosphere over Eastern Siberia - China two weeks prior to that SSW. The eastward propagating Rossby wave-trains observed in the upper troposphere one week before the SSW might have contributed to enhancement of the tropospheric anticyclone over the north-eastern Atlantic that, in turn, led to the splitting of the stratospheric polar vortex during the SSW. To investigate the SSW manifestations in the middle and upper atmosphere over Eastern Siberia, the data of ground-based spectrographic measurements of the OH (834.0 nm, band (6-2)) and O2 (864.5 nm, band (0-1)) emissions obtained at the Geophysical Observatory of the Institute of Solar-Terrestrial Physics (52N, 103E, near Irkutsk) and MLS Aura satellite data were used. An increase in the activity of planetary waves in the 2nd half of November and December 2012 was revealed. During the SSW evolution, an increase in temperature of the stratosphere ( 70 K at 10 hPa) was accompanied by mesospheric cooling which was observed in a narrow layer ( 50 K at 0.01 hPa). In late December - early January, there was significant increase of intensities of OH and O2 emissions originating at the mesosphere and low

  10. Estimating present day extreme water level exceedance probabilities around the coastline of Australia: tides, extra-tropical storm surges and mean sea level

    Science.gov (United States)

    Haigh, Ivan D.; Wijeratne, E. M. S.; MacPherson, Leigh R.; Pattiaratchi, Charitha B.; Mason, Matthew S.; Crompton, Ryan P.; George, Steve

    2014-01-01

    The occurrence of extreme water levels along low-lying, highly populated and/or developed coastlines can lead to considerable loss of life and billions of dollars of damage to coastal infrastructure. Therefore it is vitally important that the exceedance probabilities of extreme water levels are accurately evaluated to inform risk-based flood management, engineering and future land-use planning. This ensures the risk of catastrophic structural failures due to under-design or expensive wastes due to over-design are minimised. This paper estimates for the first time present day extreme water level exceedence probabilities around the whole coastline of Australia. A high-resolution depth averaged hydrodynamic model has been configured for the Australian continental shelf region and has been forced with tidal levels from a global tidal model and meteorological fields from a global reanalysis to generate a 61-year hindcast of water levels. Output from this model has been successfully validated against measurements from 30 tide gauge sites. At each numeric coastal grid point, extreme value distributions have been fitted to the derived time series of annual maxima and the several largest water levels each year to estimate exceedence probabilities. This provides a reliable estimate of water level probabilities around southern Australia; a region mainly impacted by extra-tropical cyclones. However, as the meteorological forcing used only weakly includes the effects of tropical cyclones, extreme water level probabilities are underestimated around the western, northern and north-eastern Australian coastline. In a companion paper we build on the work presented here and more accurately include tropical cyclone-induced surges in the estimation of extreme water level. The multi-decadal hindcast generated here has been used primarily to estimate extreme water level exceedance probabilities but could be used more widely in the future for a variety of other research and practical

  11. How well do CMIP5 climate models reproduce explosive cyclones in the extratropics of the Northern Hemisphere?

    Science.gov (United States)

    Seiler, C.; Zwiers, F. W.

    2016-02-01

    Extratropical explosive cyclones are rapidly intensifying low pressure systems with severe wind speeds and heavy precipitation, affecting livelihoods and infrastructure primarily in coastal and marine environments. This study evaluates how well the most recent generation of climate models reproduces extratropical explosive cyclones in the Northern Hemisphere for the period 1980-2005. An objective-feature tracking algorithm is used to identify and track cyclones from 25 climate models and three reanalysis products. Model biases are compared to biases in the sea surface temperature (SST) gradient, the polar jet stream, the Eady growth rate, and model resolution. Most models accurately reproduce the spatial distribution of explosive cyclones when compared to reanalysis data ( R = 0.94), with high frequencies along the Kuroshio Current and the Gulf Stream. Three quarters of the models however significantly underpredict explosive cyclone frequencies, by a third on average and by two thirds in the worst case. This frequency bias is significantly correlated with jet stream speed in the inter-model spread ( R ≥ 0.51), which in the Atlantic is correlated with a negative meridional SST gradient ( R = -0.56). The importance of the jet stream versus other variables considered in this study also applies to the interannual variability of explosive cyclone frequency. Furthermore, models with fewer explosive cyclones tend to underpredict the corresponding deepening rates ( R ≥ 0.88). A follow-up study will assess the impacts of climate change on explosive cyclones, and evaluate how model biases presented in this study affect the projections.

  12. Hurricane Force Winds in Explosive Maritime Extratropical Cyclones: A Modeling and Observational Study of Their Evolution and Dynamics

    Science.gov (United States)

    Albright, Benjamin Scott

    Extratropical cyclones can be as powerful as tropical cyclones with winds reaching 33 m s-1 or even stronger. They can also be very large in scale, and impact life and property on the oceans as well as over the land if the storms make a landfall. Two conceptual models exist that attempt to explain how the extreme winds in the bent-back frontal zone of these cyclones occur. The first is a jet associated with the cold conveyor belt and the second is through a phenomenon known as a sting jet. Some of the objectives this thesis will address are: (1) The role of gradient wind is during the life-cycle of the cyclone, (2) how model results compare to actual observations, and (3) if the sting jet or cold conveyor belt jet are the only causes for high winds within the bent-back frontal zone, among others. This thesis will examine two case studies of extreme, extratropical cyclones that occurred over the North Atlantic Ocean. Extensive observations including dropsondes, Stepped Frequency Microwave Radiometer (SFMR) measurements from a NOAA WP-3D aircraft and satellite scatterometer measurements are used to compare with modeled results of the two case studies. The Weather Research and Forecasting (WRF) Model Version 3.4.1 and the NOAA Environmental Modeling System (NEMS) NMM-B Launcher are used to model the two case studies and for high resolution and sensitivity testing. Trajectories calculated by the Read/Interpolate/Plot program and cross sections are additional tools used in the study. Some of the major conclusions included identifying sting jets in each storm but they were found not to be the major cause of the highest winds within the bent-back frontal zone. A secondary stream of air that accelerates from the west of the rapidly intensifying cyclone into a low-level jet located within a larger pressure gradient force and thermal gradient was found to be the major source of the high winds. It is suggested that the findings and conclusions based on the results of this

  13. Internal structure of ex-Typhoon Phanfone (2014) under an extratropical transition as observed by the research vessel Mirai

    Science.gov (United States)

    Katsumata, Masaki; Mori, Shuichi; Geng, Biao; Inoue, Jun

    2016-09-01

    The internal structure of Typhoon Phanfone (2014) undergoing "extratropical transition" over ocean was captured from the research vessel Mirai. The observed time series from world first shipboard polarimetric weather radar and frequent radiosonde launches revealed both dynamic and thermodynamic structure simultaneously in detail for four phases: cirrus shield, warm front, precipitation core, and western flank. To the east of the low-pressure center, a warm front developed along the midlatitude baroclinic zone. In the eastern vicinity of the center, remnants of the warm core worked to enhance precipitation through convergence and frontogenesis against cold ambient air. This frontogenesis and related latent heating/cooling are suggested to maintain/enhance convection in these phases. In contrast, the warm core suppressed convection in the northern/western vicinity of the low-pressure center.

  14. Modulation of air-sea fluxes by extratropical planetary waves and its impact during the recent surface warming slowdown

    Science.gov (United States)

    Molteni, Franco; Farneti, Riccardo; Kucharski, Fred; Stockdale, Timothy N.

    2017-02-01

    It is widely accepted that natural decadal variability played a major role in the slowdown in global warming observed in the 21st century, with sea surface cooling in the tropical Pacific recognized as a major contributor. However, the warming pause was most pronounced during boreal winter, with Northern Hemisphere flow anomalies also playing a role. Here we quantify the contribution of extratropical heat exchanges by comparing geopotential and temperature anomalies simulated by ensembles of seasonal forecasts with similar ocean temperature but different heat fluxes north of 40°N, as a result of planetary wave variability. We show that an important part of heat flux anomalies is associated with decadal variations in the phase of a specific planetary wave pattern. In model simulations covering the last three decades, this variability pattern accounts for a decrease of 0.35°C/decade in the post-1998 wintertime temperature trend over northern continents.

  15. On the role of extratropical air-sea interaction in the persistence of the Southern Annular Mode

    Science.gov (United States)

    Xiao, Bei; Zhang, Yang; Yang, Xiu-Qun; Nie, Yu

    2016-08-01

    Using the daily atmosphere and ocean reanalysis data, this study highlights the role of extratropical air-sea interaction in the variability of the Southern Annular Mode (SAM). Our analysis shows that the SAM-induced meridional dipolar sea surface temperature (SST) anomalies, through surface heat fluxes, can maintain persistent lower tropospheric temperature anomalies, which further results in anomalous eddy momentum forcing enhancing the persistence of the SAM. With the Finite Amplitude Wave Activity diagnosis, we illustrate that response of the eddy momentum forcing to SST anomalies can be attributed to changes in both baroclinic processes as baroclinic eddy generation and barotropic processes as wave breaking thus resultant diffusive eddy mixing, with the former confined at high latitudes and the latter strongest at midlatitudes. Spectral analysis further suggests that the above air-sea interactions are important for bimonthly and longer time scale SAM variations. The dipolar SST pattern may be an indicator for predicting subseasonal and interseasonal variabilities of the SAM.

  16. NUMERICAL EXPERIMENTS OF EFFECT OF SSTA OVER THE INDIAN OCEAN ON ATMOSPHERIC LOW-FREQUENCY OSCILLATION IN THE EXTRATROPICAL LATITUDE

    Institute of Scientific and Technical Information of China (English)

    QIU Ming-yu; LU Wei-song; CHEN Hui-lin; CAI Qin-bo

    2007-01-01

    Numerical experiments on forcing dissipation and heating response of dipole (unipole) are carried out using global spectral models with quasi-geostrophic barotropic vorticity equations. For each experiment nodel integration is run for 90 days on the condition of three-wave quasi-resonance. The results are given as follows: Under the effects of dipole (unipole) forcing source and basic flow intensity, there exist strong interactions among the three planetary waves and quasi-biweekly and intraseasonal oscillation of the three planetary waves. In the meantime, the changes in the intensity of dipole or unipole forcing source and basic flow have different frequency modulation effects on LFO in the middle and higher latitudes.The results of the stream function field of three quasi-resonant waves evolving with time confirm that the low-frequency oscillation exists in extratropical latitude.

  17. Cirrus and water vapor transport in the tropical tropopause layer – Part 1: A specific case modeling study

    Directory of Open Access Journals (Sweden)

    T. Dinh

    2012-10-01

    Full Text Available In a simulation of a tropical-tropopause-layer (TTL cirrus forced by a large-scale equatorial Kelvin wave, the radiatively induced mesoscale dynamics of the cloud actively contributes to the transport of water vapor in the vertical direction.

    In a typical TTL cirrus, the heating that results from absorption of radiation by ice crystals induces a mesoscale circulation. Advection of water vapor by the radiatively induced circulation leads to upward advection of the cloudy air. Upward advection of the cloudy air is equivalent to upward transport of water vapor when the air above the cloud is drier than the cloudy air. On the other hand, ice nucleation and depositional growth, followed by sedimentation and sublimation lead to downward transport of water vapor.

    Under the conditions specific to our simulation, the upward transport of water vapor by the mesoscale circulation dominates the downward transport by microphysical processes. The net result is upward transport of water vapor, which is equivalent to hydration of the lower stratosphere. Sensitivity to model conditions and parameters will be discussed in a follow-up paper.

  18. Long-term climatology of air mass transport through the Tropical Tropopause Layer (TTL during NH winter

    Directory of Open Access Journals (Sweden)

    K. Krüger

    2007-09-01

    Full Text Available A long-term climatology of air mass transport through the tropical tropopause layer (TTL is presented, covering the period from 1962–2005. The transport through the TTL is calculated with a Lagrangian approach using radiative heating rates as vertical velocities in an isentropic trajectory model. We demonstrate the improved performance of such an approach compared to previous studies using vertical winds from meteorological analyses. Within the TTL, the averaged diabatic ascent is 0.5 K/day during Northern Hemisphere (NH winters 1992–2001, close to observations from the tape recorder. Climatological maps show a cooling and strengthening of this part of the residual circulation during the late 1990s and early 2000s compared to the long-term mean. Lagrangian cold point (LCP fields show systematic differences for varying time periods and natural forcing components. The interannual variability of LCP temperature and density fields are found to be influenced by volcanic eruptions, ENSO, QBO and the solar cycle. The coldest and driest TTL is reached during QBOE and La Niña over the western Pacific, whereas during volcanic eruptions, El Niño and QBOW it is warmer and less dry.

  19. Long-term climatology of air mass transport through the Tropical Tropopause Layer (TTL during NH winter

    Directory of Open Access Journals (Sweden)

    K. Krüger

    2008-02-01

    Full Text Available A long-term climatology of air mass transport through the tropical tropopause layer (TTL is presented, covering the period from 1962–2005. The transport through the TTL is calculated with a Lagrangian approach using radiative heating rates as vertical velocities in an isentropic trajectory model. We demonstrate the improved performance of such an approach compared to previous studies using vertical winds from meteorological analyses. Within the upper part of the TTL, the averaged diabatic ascent is 0.5 K/day during Northern Hemisphere (NH winters 1992–2001. Climatological maps show a cooling and strengthening of this part of the residual circulation during the 1990s and early 2000s compared to the long-term mean. Lagrangian cold point (LCP fields show systematic differences for varying time periods and natural forcing components. The interannual variability of LCP temperature and density fields is found to be influenced by volcanic eruptions, El Niño Southern Oscillation (ENSO, Quasi-Biennial Oscillation (QBO and the solar cycle. The coldest and driest TTL is reached during QBO easterly phase and La Niña over the western Pacific, whereas during volcanic eruptions, El Niño and QBO westerly phase it is warmer and less dry.

  20. A Numerical Study on the Effect of an Extratropical Cyclone on the Evolution of a Midlatitude Front

    Institute of Scientific and Technical Information of China (English)

    CHEN Guanghua

    2013-01-01

    The extratropical transition (ET) of tropical cyclone (TC) Haima (2004) was simulated to understand the impact of TC on midlatitude frontal systems.Two experiments were conducted using the Advanced Research version of the Weather Research and Forecast (WRF) model.In the control run (CTL),a vortex was extracted from the 24-hour pre-run output and then inserted into the National Centers for Environmental Prediction (NCEP) global final (FNL) analysis as an initial condition,while TC circulation was removed from the initial conditions in the sensitivity run (NOTC).Comparisons of the experiments demonstrate that the midlatitude front has a wider meridional extent in the NOTC run than that in the CTL run.Furthermore,the CTL run produces convection suppression to the southern side of the front due to strong cold advection related to the TC circulation.The easterly flow north of the TC not only decelerates the eastward displacement of the front and contracts its zonal scale but also transports more moisture westward and lifts the air along equivalent potential temperature surfaces ahead of the front.As a result,the ascending motion and diabatic heating are enhanced in the northeastern edge of the front,and the anticyclonic outflow in the upper-level is intensified.The increased pressure gradient and divergent flow aloft strengthen the upper-level jet and distort the trough axis in a northwest-southeast orientation.The thermal contrast between the two systems and the dynamic contribution related to the TC circulation can facilitate scalar and rotational frontogenesis to modulate the frontal structure.

  1. The Extratropical Influence of the Madden-Julian Oscillation on Wintertime Blocking

    Science.gov (United States)

    Henderson, S. A.; Maloney, E. D.; Barnes, E. A.

    2016-12-01

    Wintertime atmospheric blocking is associated with severe long-lasting weather conditions in the Northern Hemisphere. Studies have shown that the primary mode of tropical intraseasonal variability, the Madden-Julian Oscillation (MJO), significantly influences important factors for blocking, including the North Atlantic Oscillation and Rossby wave breaking. However, the extent to which the MJO impacts the occurrence of winter blocking is not yet fully understood. The occurrence of North Pacific, North Atlantic, and European blocking is examined during the lifecycle of the MJO. Findings demonstrate a significant MJO influence on atmospheric blocking in all three regions, with a near doubling in east Pacific, Atlantic, and European blocking frequency following certain MJO phases. It is suggested that the increase in European blocking is a result of two conditions: 1) a pre-existing anomalous anticyclone in the North Atlantic, and 2) a preceding negative Pacific-North American (PNA) pattern triggered and influenced by MJO convection.

  2. 飓风“桑迪”温带变性过程特征分析%Characteristics of extratropical transition of hurricane Sandy

    Institute of Scientific and Technical Information of China (English)

    黄蔚薇; 董静舒; 王洁; 许映龙

    2015-01-01

    Based on the 1°×1°NCEP reanalysis data,characteristics of extratropical transition of hurricane Sandy were analyzed.The results indicate that thermal asymmetry of extratropical transition system is displayed directly u-sing thickness fields in low,middle and upper levels of the troposphere,which is favorable to diagnose the extrat-ropical transition of hurricane.Vorticity field could diagnose the coupling of upper-level trough and hurricane,and the extratropical transition begins because the hurricane is impacted by the baroclinic trough after the combination of their positive vorticity.The strong convection during the process of extratropical transition could be enhanced by forced rising of thickness deformation field,lifting of lower frontal zone,positive feedback of condensation and in-creasing upper divergence,which are also reasons of westerly deviation of strong upwarding zone.The warm core of hurricane Sandy falls to the middle and lower levels of the troposphere,which is associated with the sink of strong ascending motion.The warm core can be ruined by strong cold advection,but moderate cold air advection is in favor of Sandy′s redevelopment.Temperature advection distribution at 850 hPa is indicative to Sandy′s track during the extratropical transition process,which approximately parallels the connection between warm and cold ad-vection centers.%利用 NCEP 的1°×1°资料,分析飓风“桑迪”温带变性前后物理量的特征和变化。结果表明:利用对流层低层、中层及高层的厚度场可立体直观地展现热带气旋中心热力结构的对称性,便于进行飓风温带变性的诊断分析。涡度场可诊断高空槽和飓风耦合的情况,两者的正涡度场连接后使热带气旋受到高空槽的影响开始变性。厚度变形场动力强迫上升、低层锋区抬升、强降水区凝结潜热正反馈作用和高空辐散加强等有利于飓风“桑迪”变性过程中深对流的维持及发展

  3. Exploring alternative wind vulnerability and loss modeling methods - application to Europe extra-tropical cyclones

    Science.gov (United States)

    Peiris, N.

    2009-04-01

    Catastrophe models are used to assess the economic and insured loss to the built environment due to natural hazards such as earthquakes, windstorms, floods, storm surges, tsunamis, etc. A conventional catastrophe model estimating direct economic loss could be divided into three basic components; hazard, vulnerability and exposure. For a single event, the hazard component represents the best estimate realization of the hazard footprint over a region at the modeling resolution, i.e. variable grid, postalcode, cresta, etc. The vulnerability component represents the response of the buildings or any modeled structure to the hazard, quantified in terms of a loss ratio. The exposure component represents the value of the buildings in a portfolio covering a region or those underwritten by an insurer or a re-insurer. The exposure together with the vulnerability functions produces the expected economic loss of the hazard footprint for a given hazard event. In the case of estimating indirect economic losses and insured losses financial models are utilized with various financial structures applied on the economic loss estimates. The commonly used method of characterizing wind vulnerability of buildings is to develop functions of mean loss ratio or mean damage ratio (MDR) vs wind speed where the wind speed is often defined as the peak gust measured at a height of 10m above the ground elevation. The uncertainty associated with MDR due to the likelihood of the building experiencing a range of damage states and hence loss ratios at a given wind speed is quantified by a continuous statistical distribution with a mean (which is the MDR) and a standard deviation, SD. For a given event footprint a conventional catastrophe model calculates an MDR and associated SD for each location of a building portfolio. This together with the location exposure or insured value results in the location loss. The location losses are then aggregated together with their SDs to obtain the total expected

  4. A first global-scale hindcast of extreme sea levels induced by extra-tropical storms

    Science.gov (United States)

    Muis, Sanne; Verlaan, Martin; Winsemius, Hessel; Ward, Philip

    2015-04-01

    Flood risk in coastal areas has been increasing in past years. This can be partly attributed to climate change and rising sea levels that increase the likelihood of coastal flood hazards, but also to increasing flood exposure because the global population and capital is increasingly concentrated in coastal zones. Without action, the increasing trends in flood hazard and exposure will be associated with catastrophic flood losses in the future. The adequate allocation of global investments and prioritization of adaptation actions requires an accurate understanding of the current and future coastal flood risk on a global-scale. Despite this, global data on extreme sea levels are scarce. A few studies have assessed coastal flood risk at the global-scale. To date, these have been either based on extreme water levels in the DIVA database or on observations from tide gauges. Both datasets have limitations when assessing flood risk, including low-probability events, on a fully global scale. Hence, there is a need for an improved estimation of extreme sea level on a global-scale. Therefore, we are developing the first global hindcast of coastal water levels which covers the period 1979-2013. To do this, we apply a global hydrodynamic model which is based on the Delft3D Flexible Mesh software from Deltares. By forcing the model with the tidal potential and meteorological fields derived from the ERA-Interim global reanalysis, we are able to simulate the water levels resulting from tides and surges. Subsequently, we apply extreme value statistics to estimate exceedance probabilities. Similar hydrodynamic modelling efforts have been carried out at the regional scale, but as the modelling of surges in shallow coastal areas requires a high-resolution model grid, generally this approach is computationally too costly on a global-scale. However, the recent application of unstructured grids (or flexible mesh) in hydrodynamic models, allowing local refinement of the grid, has enabled

  5. Cold trap dehydration in the Tropical Tropopause Layer characterised by SOWER chilled-mirror hygrometer network data in the Tropical Pacific

    Directory of Open Access Journals (Sweden)

    F. Hasebe

    2013-04-01

    Full Text Available A network of balloon-borne radiosonde observations employing chilled-mirror hygrometers for water and electrochemical concentration cells for ozone has been operated since the late 1990s in the Tropical Pacific to capture the evolution of dehydration of air parcels advected quasi-horizontally in the Tropical Tropopause Layer (TTL. The analysis of this dataset is made on isentropes taking advantage of the conservative properties of tracers moving adiabatically. The existence of ice particles is diagnosed by lidars simultaneously operated with sonde flights. Characteristics of the TTL dehydration are presented on the basis of individual soundings and statistical features. Supersaturations close to 80% in relative humidity with respect to ice (RHice have been observed in subvisible cirrus clouds located near the cold point tropopause at extremely low temperatures around 180 K. Although further observational evidence is needed to confirm the credibility of such high values of RHice, the evolution of TTL dehydration is evident from the data in isentropic scatter plots between the sonde-observed mixing ratio (OMR and the minimum saturation mixing ratio (SMRmin along the back trajectories associated with the observed air mass. Supersaturation exceeding the critical value of homogeneous ice nucleation (OMR > 1.6 × SMRmin is frequently observed on the 360 and 365 K surfaces indicating that cold trap dehydration is in progress in the TTL. The near correspondence between the two (OMR ~ SMRmin at 380 K on the other hand implies that this surface is not sufficiently cold for the advected air parcels to be dehydrated. Above 380 K, cold trap dehydration would scarcely function while some moistening occurs before the air parcels reach the lowermost stratosphere at around 400 K where OMR is generally smaller than SMRmin.

  6. Are temperature reconstructions regionally biased?

    CERN Document Server

    Bothe, O

    2012-01-01

    Are temperature reconstructions possibly biased due to regionally differing density of utilized proxy-networks? This question is assessed utilizing a simple process-based forward model of tree growth in the virtual reality of two simulations of the climate of the last millennium with different amplitude of solar forcing variations. The pseudo-tree ring series cluster in high latitudes of the northern hemisphere and east Asia. Only weak biases are found for the full network. However, for a strong solar forcing amplitude the high latitudes indicate a warmer first half of the last millennium while mid-latitudes and Asia were slightly colder than the extratropical hemispheric average. Reconstruction skill is weak or non-existent for two simple reconstruction schemes, and comparison of virtual reality target and reconstructions reveals strong deficiencies. The temporal resolution of the proxies has an influence on the reconstruction task and results are sensitive to the construction of the proxy-network. Existing ...

  7. Diagnosing the Influence of Diabatic Processes on the Explosive Deepening of Extratropical Cyclones over the North Atlantic Ocean

    Science.gov (United States)

    Knippertz, P.; Fink, A. H.; Pohle, S.; Pinto, J. G.

    2012-04-01

    The relative roles of baroclinic and diabatic processes for explosive deepening of extratropical cyclones have been debated for a long time, mostly on the basis of case studies. Here we present a powerful diagnostic approach to the problem, which is based on a combination of an automatic cyclone tracking with a special version of the classical pressure tendency equation (PTE) that relates changes in surface pressure to contributions from horizontal and vertical temperature advection as well as diabatic processes, i.e., mainly latent heat release in clouds. Along the entire track of a cyclone, the PTE is evaluated in a 3°x3° box from the surface to 100 hPa centred on the location the storm is moving to within the next time step. The great advantage of this new approach is the easy applicability to large gridded datasets, even if diabatic tendencies are not explicitly available as in many reanalysis products. The strengths and limitations of the method are illustrated here through application to several explosively deepening, damaging winter storms over the North Atlantic Ocean. Data used are 6-hourly ERA-Interim re-analyses. For better interpretation of the results, the PTE analysis is complemented with other classical cyclogenetic factors, i.e., the strength of the polar jet and the equivalent-potential temperature θe at 850 hPa in the warm sector. The main conclusions from this analysis are: • The time evolutions of the actual core pressure of the storm and the 6-hourly pressure changes in the moving box used to evaluate the PTE show structural similarities that are dominated by the explosive deepening. • The vertical advection term is positive throughout the entire lifecycle of all storms indicating the dominance of ascent downstream of the cyclone center. It is (over-) compensated by negative contributions through warm advection and diabatic heating. • Storms "Martin" and "Kyrill" are dominated by baroclinic processes with contributions of diabatic

  8. 热带对流层顶层结构的变化特征和趋势%Variation Characteristics and Trends of the Tropical Tropopause Layer Structure

    Institute of Scientific and Technical Information of China (English)

    辛玉姣; 田文寿

    2011-01-01

    Using the ECMWF Interim Re-Analysis (ERA-Interim) data from 1989 to 2008 and the simulations from 1980 to 2019, which are produced by a chemistry- climate model, variation characteristics and trends of the tropical tropopause layer (TTL) structure are analyzed. It is found that the TTL characteristics have significant sea-sonal and spatial variations. The thickness of the TTL in summer and autumn is the thinnest in the Northern Hemi-sphere and it has the largest seasonal variability in winter in the Northern Hemisphere. ERA-Interim data indicates that the TTL temperature increased significantly in 1991 because of the Pinatubo volcanic eruption, and the tempera-ture decreased after that from 1992 to 1995. The TTL temperature has been increasing since 1996 without consider-ing the impact of Pinatubo volcanic eruption. In recent years the TTL is getting higher, warmer and thinner, and the stratospheric water vapor is also increasing. The chemistry - climate model simulations show the same trends.%利用1989~2008年欧洲中期天气预报中心高时空分辨率的再分析资料以及1980~2019年的大气化学—气候模式模拟资料分析了热带对流层顶层(Tropical Tropopause Layer,T TL)结构的变化特征,并且预测了其未来变化趋势.结果表明,TTL结构存在明显的季节和空间变化.其厚度在北半球的春、秋两季比较薄,其季节变率在北半球的冬季最大;再分析资料表明1991年皮纳图博(Pinatubo)火山爆发导致对流层顶温度大幅升高,1992~1995年之间对流层顶温度明显下降.不考虑火山爆发的影响,1996年后对流层顶温度有所升高.近年来热带对流层顶层有抬升增暖的趋势,厚度有所减小,平流层水汽含量增多.大气化学气候模式资料预测的TTL的特征从1980~2019年也是同样的趋势.

  9. Investigation of downscaling techniques for the linkage of global and regional air quality modeling

    Directory of Open Access Journals (Sweden)

    Y. F. Lam

    2009-07-01

    Full Text Available Recent year, downscaling global atmospheric model outputs for the USEPA Community Multiscale Air Quality (CMAQ Initial (IC and Boundary Conditions (BC have become practical because of the rapid growth of computational technologies that allow global simulations can be completed within a reasonable time and have better performance. The traditional method of generating IC/BC by profile data has lost its advocators due to the weakness of the limited horizontal and vertical variations found on the gridded boundary layers. In this paper, we are in effort to investigate the effects of using profile IC/BC and global atmospheric model data. We utilize the GEOS-Chem model outputs to generate time-varied and layer-varied IC/BC for year 2002 using our newly development of tropopause determining algorithm. The purpose of the study is to determine the tropopause effect to the downscaling process. From the results, we have found that without considering tropopause in the downscaling process created unrealistic O3 concentrations in IC/BC at the upper boundary conditions for regional tropospheric model. This phenomenon has caused over-prediction of surface O3 in CMAQ. And it is greatly affected by temperature and latitudinal location. With the implementation of our algorithm, we have successfully resolved the incompatibility issues in the vertical layer structure between global and regions chemistry models to yield better surface O3 predictions than profile IC/BC on both summer and winter conditions. At the same time, it improved the vertical O3 distribution of CMAQ outputs. The algorithm can be applied to a global atmospheric model which performs a reasonable outcome to determine the tropopause.

  10. Caractérisation de la tropopause extratropicale avec les données aéroportées
    MOZAIC : zone de mélange et d'échange

    OpenAIRE

    2006-01-01

    This thesis aims atMOZAIC data analyses and to improve understanding of Stratosphere-Troposphere Exchange (STE) on case study scale or global scale. The use of Lagrangiantechniques and the mesoscale model MESO-NH underlines importance of STE into a summertimecyclogenesis case study. It characterizes a deep stratospheric intrusion and theimpact of convective mixing across the tropopause on chemical distribution into the UTLSregion. A lagrangian analysis of a second case study shows that fronta...

  11. Cirrus clouds, humidity, and dehydration in the tropical tropopause layer observed at Paramaribo, Suriname (5.8°N, 55.2°W)

    Science.gov (United States)

    Immler, Franz; Krüger, Kirstin; Tegtmeier, Susann; Fujiwara, Masatomo; Fortuin, Paul; Verver, Gé; Schrems, Otto

    2007-02-01

    In the framework of the European Project STAR the Mobile Aerosol Raman Lidar (MARL) of the Alfred Wegener Institute (AWI) was operated in Paramaribo, Suriname (5.8°N, 55.2°W), and carried out extensive observations of tropical cirrus clouds during the local dry season from 28 September 2004 to 16 November 2004. The coverage with ice clouds was very high with 81% in the upper troposphere (above 12 km). The frequency of occurrence of subvisual clouds was found to be clearly enhanced compared to similar observations performed with the same instrument at a station in the midlatitudes. The extinction-to-backscatter ratio of thin tropical cirrus is with 26 ± 7 sr significantly higher than that of midlatitude cirrus (16 ± 9 sr). Subvisual cirrus clouds often occur in the tropical tropopause layer (TTL) above an upper tropospheric inversion. Our observations show that the ice-forming ability of the TTL is very high. The transport of air in this layer was investigated by means of a newly developed trajectory model. We found that the occurrence of clouds is highly correlated with the temperature and humidity history of the corresponding air parcel. Air that experienced a temperature minimum before the measurement took place was generally cloud free, while air that was at its temperature minimum during the observation and thus was saturated contained ice. We also detected extremely thin cloud layers slightly above the temperature minimum in subsaturated air. The solid particles of such clouds are likely to consist of nitric acid trihydrate (NAT) rather than ice.

  12. 北半球温带气旋客观研究方法及模拟和预估的研究进展%A Review of the Research on Objective Method and Simulation and Projection of Extratropical Cyclone over the Northern Hemisphere

    Institute of Scientific and Technical Information of China (English)

    张颖娴; 丁一汇

    2015-01-01

    reanalysis data and GCM, the research method of extratropical cyclones shifts from subjective analysis to objective identiifcation; (2) There are two main activity centers and two subordinate activity centers displayed by reanalysis and model data, with the main activity center located in the North Paciifc and North Atlantic region, and the subordinate activity center located in Mediterranean and Mongolian regions;(3) Under the inlfuence of climate change scenarios by human activities, extratropical cyclones will diminish in most parts of the Northern Hemisphere, and increase in individual districts; (4) Different thresholds, different physical quantities, and considerations of different atmospheric vertical levels add to a picture which can be combined to get an uncertainty view of cyclones, their variability, and trends, in the real world and in GCM studies. Hence, the urgent need for an in-depth understanding of cyclones is more speciifc intercomparison studies which can demonstrate the differences between the approaches and their results.

  13. Global large-scale stratosphere-troposphere exchange in modern reanalyses

    Science.gov (United States)

    Boothe, Alexander C.; Homeyer, Cameron R.

    2017-05-01

    Stratosphere-troposphere exchange (STE) has important impacts on the chemical and radiative properties of the upper troposphere and lower stratosphere. This study presents a 15-year climatology of global large-scale STE from four modern reanalyses: ERA-Interim, JRA-55, MERRA-2, and MERRA. STE is separated into three regions (tropics, subtropics, and extratropics) and two transport directions (stratosphere-to-troposphere transport or STT and troposphere-to-stratosphere transport or TST) in an attempt to identify the significance of known transport mechanisms. The extratropics and tropics are separated by the tropopause break. Any STE occurring between the tropics and the extratropics through the tropopause break is considered subtropical exchange (i.e., in the vicinity of the subtropical jet). In addition, this study employs a method to identify STE as that which crosses the lapse-rate tropopause (LRT), while most previous studies have used a potential vorticity (PV) isosurface as the troposphere-stratosphere boundary. PV-based and LRT-based STE climatologies are compared using the ERA-Interim reanalysis output. The comparison reveals quantitative and qualitative differences, particularly for TST in the polar regions. Based upon spatiotemporal integrations, we find STE to be STT dominant in ERA-Interim and JRA-55 and TST dominant in MERRA and MERRA-2. The sources of the differences are mainly attributed to inconsistencies in the representation of STE in the subtropics and extratropics. Time series during the 15-year analysis period show long-term changes that are argued to correspond with changes in the Brewer-Dobson circulation.

  14. Long-term trends in synoptic-scale Rossby wave-breaking and the jet strength at tropopause levels

    Science.gov (United States)

    Isotta, F.; Martius, O.; Sprenger, M.; Schwierz, C.

    2009-04-01

    Breaking synoptic-scale Rossby waves are frequent features of the upper troposphere and lower stratosphere (UTLS) which affect both global- and regional-scale dynamics. Furthermore, they directly influence ozone distribution through meridional transport of ozone-rich air towards the south and ozone-poor air towards the north. Here, trends in the frequency of these breaking waves are assessed by analysing a 44-year climatology (1958-2002) of potential vorticity (PV) streamers on isentropic surfaces from 310 to 350 K. These streamers are viewed as breaking Rossby waves. Two complementary techniques are used to analyse the trends. First, linear trends are computed using the least-squares regression technique. Statistically significant linear trends are found to vary in location and magnitude between isentropic levels and the four seasons. In winter significant trends are detected in the eastern Pacific between 340 and 350 K. A positive trend of stratospheric streamers in the Tropics is related to an increase of total column ozone, whereas the positive trend of tropospheric streamers in the mid-latitudes is associated with a decrease of total ozone. Secondly, a nonlinear trend analysis is performed using the seasonal-trend decomposition procedure based on Loess (STL). With this technique, the low-frequency variability of the time series is analysed during the 44-year period. For instance, over the eastern Atlantic on 350 K, a phase of decreasing PV streamer frequencies in the 1950s and 1960s is followed by a positive streamer tendency after the 1970s. Additionally, trends of the zonal wind are investigated. One prominent outcome of this analysis is the observation that equatorial easterlies over the Atlantic are weakening. A dynamically meaningful link exists between the trends observed in both wind velocity and PV streamers.

  15. Diagnostic analysis of the extratropical re-intensification of tropical cyclones over mainland of China%中国大陆上变性加强热带气旋的诊断分析

    Institute of Scientific and Technical Information of China (English)

    李侃; 徐海明

    2011-01-01

    Based on the Tropical Cyclone (TC) Yearbook's data of JMA from 1979 to 2007, statistical analyses were performed to study the extratropical transition ( ET) of tropical cyclones over mainland of China. Results indicated that there were 16 tropical cyclones over the mainland of China, which accounted for 8. 56% of the total number of tropical cyclones that made landfall on China during the 29 a, only 8 of these ET cases got strengthened after transition. In addition, the moist potential vorticity ( MPV ) and the dynamic, thermodynamic processes analyses of the 8 ET cases're-intensification revealed that the combination of the dynamic and thermodynamic processes was able to define a development region in which it was favorable for intensification of most ET cases over mainland of China during the 29 a. Moreover, the upper-level positive MPV propagated downward to low-level during the obvious re-intensification phase of ET, however, the upper-level positive MPV did not always propagate downward when the ET of TC was reinforced only a little.%利用1979-2007年日本气象厅热带气旋年鉴资料,对在中国大陆上发生变性的热带气旋进行了统计分析,结果表明:29 a间中国大陆上发生变性的热带气旋共有16个,占登陆中国热带气旋总数的8.56%,其中8个变性后加强.利用日本JRA-25再分析资料诊断分析了这8个变性加强热带气旋的湿位涡垂直分布特征以及影响热带气旋变性发展的热力、动力因子,结果表明:29 a间中国大陆上大部分变性热带气旋的再加强均与中高层动力因子和低层热力因子所组成的发展区密切相关;变性加强明显的热带气旋,其高层的正湿位涡下传至低层,而变性加强幅度较小的热带气旋,其高层正湿位涡并不一定会下传至低层.

  16. Comparing hurricane and extratropical storm surge for the Mid-Atlantic and Northeast Coast of the United States for 1979-2013

    Science.gov (United States)

    Booth, J. F.; Rieder, H. E.; Kushnir, Y.

    2016-09-01

    This letter examines the magnitude, spatial footprint, and paths of hurricanes and extratropical cyclones (ETCs) that caused strong surge along the east coast of the US between 1979 and 2013. Lagrangian cyclone track information, for hurricanes and ETCs, is used to associate surge events with individual storms. First, hurricane influence is examined using ranked surged events per site. The fraction of hurricanes among storms associated with surge decreases from 20%-60% for the top 10 events to 10%-30% for the top 50 events, and a clear latitudinal gradient of hurricane influence emerges for larger sets of events. Secondly, surges on larger spatial domains are examined by focusing on storms that cause exceedance of the probabilistic 1-year surge return level at multiple stations. Results show that if the strongest events in terms of surge amplitude and spatial extent are considered, then hurricanes are most likely to create the hazards. However, when slightly less strong events that still impact multiple areas during the storm life cycle are considered, the relative importance of hurricanes shrinks as that of ETCs grows. Furthermore we find distinct paths for ETCs causing multi-site surge at individual segments of the US east coast.

  17. Multiple signal propagation at the tropopause of the Venusian atmosphere: new insights from the Radio Science Experiment (VeRa) onboard Venus Express

    Science.gov (United States)

    Herrmann, Maren; Oschlisniok, Janusz; Remus, Stefan; Tellmann, Silvia; Häusler, Bernd; Pätzold, Martin

    2016-10-01

    The rapid change of the refractive index over a short altitude range in a planetary atmosphere can lead to multi-path effects when sounding the atmosphere with radio waves. The Radio Science Experiment (VeRa) [1,2] onboard Venus Express sounded the Venusian atmosphere from 90 km downward to 40 km altitude[3,4]. More than 800 profiles of temperature, pressure and neutral number density could be retrieved which cover almost all local times and latitudes. A specially developed analysis method based on the VeRa open loop receiving technique deciphers the multi-path effect and identifies an inversion layer near the tropopause at an altitude of about 60km. This layer is of particular interest - it separates the stratified troposphere from the highly variable mesosphere and can be a likely location for the formation of gravity waves [5]. The new retrieval method shows an inversion layer up to 15 K colder than commonly thought. Local time and latitude dependence including the influence of the spacecraft trajectory on this effect will be discussed. These results will contribute to a consistent picture of the Venus' thermal atmosphere structure and therefore help to improve atmospheric models.[1] Häusler, B. et al: 'Radio science investigations by VeRa onboard the Venus Express spacecraft' Planetary and Space Science 54, 2006[2] Häusler, B. et al, 'Venus Atmospheric, Ionospheric, Surface and Interplanetery Radio-Wave Propagation Studies with the VeRa Radio Science experiment' Eur. Space Agencys, Spec. Publ., ESA SP 1295, 2007[3] Pätzold, M. et al: 'The structure of Venus' middle atmosphere and ionosphere', Nature 450, 2007[4] Tellmann, S. et al : 'Structure of the Venus neutral atmosphere as observed by the Radio Science experiment VeRa on Venus Express', Journal of Geophysical Research 114, 2009[5] Tellmann, S. et al: 'Small-scale temperature fluctuations seen by the VeRa Radio Science Experiment on Venus Express' Icarus 221, 2012.

  18. Upscaling the impact of convective overshooting (COV) through BRAMS: a continental and wet-season scale study of the water vapour (WV) budget in the tropical tropopause layer (TTL).

    Science.gov (United States)

    Behera, Abhinna; Rivière, Emmanuel; Marécal, Virginie; Rysman, Jean-François; Claud, Chantal; Burgalat, Jérémie

    2017-04-01

    The stratospheric water vapour (WV) has a conceding impact on the radiative and chemical budget of Earth's atmosphere. The convective overshooting (COV) at the tropics is well admitted for playing a role in transporting directly WV to the stratosphere. Nonetheless, its impact on the lower stratosphere is yet to be determined at global scale, as the satellite and other air-borne measurements are not of having fine enough resolution to quantify this impact at large scale. Therefore, efforts have been made to quantify the influence of COV over the WV budget in the tropical tropopause layer (TTL) through modelling. Our approach is to build two synthetic tropical wet-seasons; where one would be having only deep convection (DC) but no COV at all, and the second one would be having the COV, and in both cases the WV budget in the TTL would be estimated. Before that, a French-Brazilian TRO-pico campaign was carried out at Bauru, Brazil in order to understand the influence of COV on the WV budget in the TTL. The radio-sounding, and the small balloon-borne WV measurements from the campaign are being utilized to validate the model simulation. Brazilian version of Regional Atmospheric Modeling System (BRAMS) is used with a single grid system to simulate a WV variability in a wet-season. Grell's convective parameterization with ensemble closure, microphysics with double moment scheme and 7 types of hydrometeors are incorporated to simulate the WV variability for a wet-season at the tropics. The grid size of simulation is chosen to be 20 km x 20 km horizontally and from surface to 30 km altitude, so that there cannot be COV at all, only DC due to such a relatively coarse resolution. The European Centre for Medium-range Weather Forecasts (ECMWF) operational analyses data are used every 6 hours for grid initialization and boundary conditions, and grid center nudging. The simulation is carried out for a full wet-season (Nov 2012 - Mar 2013) at Brazilian scale, so that it would

  19. The impact of the Arctic Sea Ice retreat on extratropical cyclones and anticyclones over Northern Eurasia: atmospheric model simulations

    Science.gov (United States)

    Akperov, Mirseid; Semenov, Vladimir; Mokhov, Igor; Lupo, Antony

    2015-04-01

    The Arctic region has been warming more than twice as fast as the other parts of the world during the last few decades. The rapid Arctic warming is accompanied with the dramatic change of Arctic sea ice cover. Recently, it has been suggested that such climatic changes might have led to the increase of anomalous weather events in winter over Northern Eurasia. One example is anomalous cold winters over Northern Eurasia associated with atmospheric blocking events. However, a large uncertainty remains concerning robustness of the observed relationship and associated mechanisms of impact. The main goal of this research is to explore the connection between the declining Arctic sea ice (most strongly expressed in the Barents-Kara Seas region) in the cold season and the change of cyclonic and anti-cyclonic activity over Northern Eurasia using simulations with atmospheric general circulation model (AGCM). The simulations were performed with the ECHAM5 AGCM using identical sea surface temperature climatology but different sea ice concentrations (SIC) for the periods corresponding to the high (1966-1969), low (1990-1995) and very low (2005-2012) SIC regimes in the Arctic as well as for the mean climatological SIC for 1971-2000. The duration of each simulation was 50 years. For the regimes with high and very low SIC, a statistically significant increase in the number of long-living anticyclones (with lifetime of more than 5 days) over Northern Eurasia was found. Long-living cyclones exhibited different changes in their number depending on their intensity. The analysis of the spatial patterns of cyclonic and anti-cyclonic activity over Eurasia was performed. We found an increase of the frequency of cyclones over the central region of the European part of Russia (EPR) and anticyclones over the northern region of the EPR for the regimes with a high sea ice concentration in the Arctic. For the regime with very low SIC the shift of the frequency of cyclones and anticyclones towards

  20. Regionalism, Regionalization and Regional Development

    Directory of Open Access Journals (Sweden)

    Liviu C. Andrei

    2016-03-01

    Full Text Available Sustained development is a concept associating other concepts, in its turn, in the EU practice, e.g. regionalism, regionalizing and afferent policies, here including structural policies. This below text, dedicated to integration concepts, will limit on the other hand to regionalizing, otherwise an aspect typical to Europe and to the EU. On the other hand, two aspects come up to strengthen this field of ideas, i.e. the region (al-regionalism-(regional development triplet has either its own history or precise individual outline of terms.

  1. Temperature decrease in the extratropics of South America in response to a tropical forcing during the austral winter

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, G.V. [Centro de Investigaciones Cientificas y Transferencia de Tecnologia a la Produccion (CICYTTP-CONICET), Diamante, Entre Rios (Argentina)

    2010-07-01

    This paper focuses on the dynamic mechanisms that create favorable conditions for the occurrence of frosts that affect large areas of Argentina and are denominated generalized frosts (GF). The hemispheric teleconnection patterns linked to extreme cold events affecting central and northeastern Argentina during winter are identified. The objective is to determine whether the conditions found in previous studies for the composite of winters with extreme (maximum and minimum) frequency of GF occurrence respond to typical characteristics of the austral winter or they are inherent to those particular winters. Taking the mean winter as basic state in the 1961-1990 period, a series of numerical experiments are run using a primitive equation model in which waves are excited with a thermal forcing. The positions of the thermal forcing are chosen according to observed convection anomalies in a basic state given by the austral winters with extreme frequency of GF occurrence. The wave trains excited by anomalous convection situated in specific regions may propagate across the Pacific Ocean and reach South America with the appropriate phase, creating the local favorable conditions for the occurrence of GF. However, the anomalous convection is, by itself, not sufficient since the response also depends on the basic state configuration. This is proved by placing the forcing over the region of significant anomalous convection for maximum and minimum frequency of GF occurrence and the response was very different in comparison to the mean winter. It is concluded that the conditions for a greater GF frequency of occurrence are inherent to these particular winters, so that such conditions are not present in the average winter. (orig.)

  2. European extra-tropical storm damage risk from a multi-model ensemble of dynamically-downscaled global climate models

    Directory of Open Access Journals (Sweden)

    M. R. Haylock

    2011-10-01

    Full Text Available Uncertainty in the return levels of insured loss from European wind storms was quantified using storms derived from twenty-two 25 km regional climate model runs driven by either the ERA40 reanalyses or one of four coupled atmosphere-ocean global climate models. Storms were identified using a model-dependent storm severity index based on daily maximum 10 m wind speed. The wind speed from each model was calibrated to a set of 7 km historical storm wind fields using the 70 storms with the highest severity index in the period 1961–2000, employing a two stage calibration methodology. First, the 25 km daily maximum wind speed was downscaled to the 7 km historical model grid using the 7 km surface roughness length and orography, also adopting an empirical gust parameterisation. Secondly, downscaled wind gusts were statistically scaled to the historical storms to match the geographically-dependent cumulative distribution function of wind gust speed.

    The calibrated wind fields were run through an operational catastrophe reinsurance risk model to determine the return level of loss to a European population density-derived property portfolio. The risk model produced a 50-yr return level of loss of between 0.025% and 0.056% of the total insured value of the portfolio.

  3. Impact of the Asian Summer Monsoon on the Lower Stratosphere: Results from TACTS/ESMVal 2012

    Science.gov (United States)

    Hoor, Peter; Müller, Stefan; Vogel, Bärbel; Bozem, Heiko; Fischer, Horst; Bönisch, Harald; Engel, Andreas; Keber, Timo; Krämer, Martina; Riese, Martin; Gute, Ellen; Schlager, Hans; Ziereis, Helmut; Zahn, Andreas

    2016-04-01

    We present results from the German research aircraft HALO during the TACTS/ESMVal project (Transport and Composition in the UTLS and Earth System Model Validation). We focus on the distribution of CO, N2O and ozone as well as water vapour. The measurements took place in the extratropical UTLS (upper troposphere/lower stratosphere) region over Europe from August to September 2012. Here, we focus on the northern hemispheric trace gas composition above potential temperatures of 370 K. In this region we could for the first time identify mixing lines, which indicate mixing between stratospheric air masses of different origin. Introducing a new pair of correlation species (N2O-CO) we could identify air masses, which do not involve mixing directly at the tropopause. Based on a case study we show, that the atmospheric region between the extratropical tropopause and potential temperatures up to Θ = 405 K is affected by mixing of 'young' stratospheric air from the monsoon region with aged stratospheric air. Based on the distribution of CO and N2O we show that the lower stratosphere over Europe becomes more tropospheric from August to September with enhanced CO, N2O and water vapour as well as decreasing ozone. Using comprehensive trajectory calculations our results particularly indicate that the Asian summer monoon is the main contributor to this composition change and that mixing from the tropical tropopause layer becomes weaker over time. Therefore we conclude that the monsoon significantly contributes to the flushing of the extratropical UTLS during summer and autumn.

  4. Influences of tropical-extratropical interaction on the multidecadal AMOC variability in the NCEP climate forecast system

    Science.gov (United States)

    Huang, Bohua; Hu, Zeng-Zhen; Schneider, Edwin K.; Wu, Zhaohua; Xue, Yan; Klinger, Barry

    2012-08-01

    We have examined the mechanisms of a multidecadal oscillation of the Atlantic Meridional Overturning Circulation (AMOC) in a 335-year simulation of the Climate Forecast System (CFS), the climate prediction model developed at the National Centers for Environmental Prediction (NCEP). Both the mean and seasonal cycle of the AMOC in the CFS are generally consistent with observation-based estimates with a maximum northward volume transport of 16 Sv (106 m3/s) near 35°N at 1.2 km. The annual mean AMOC shows an intermittent quasi 30-year oscillation. Its dominant structure includes a deep anomalous overturning cell (referred to as the anomalous AMOC) with amplitude of 0.6 Sv near 35°N and an anomalous subtropical cell (STC) of shallow overturning spanning across the equator. The mechanism for the oscillation includes a positive feedback between the anomalous AMOC and surface wind stress anomalies in mid-latitudes and a negative feedback between the anomalous STC and AMOC. A strong AMOC is associated with warm sea surface temperature anomaly (SSTA) centered near 45°N, which generates an anticyclonic easterly surface wind anomaly. This anticyclonic wind anomaly enhances the regional downwelling and reinforces the anomalous AMOC. In the mean time, a wind-evaporation-SST (WES) feedback extends the warm SSTA to the tropics and induces a cyclonic wind stress anomaly there, which drives a tropical upwelling and weakens the STC north of the equator. The STC anomaly, in turn, drives a cold upper ocean heat content anomaly (HCA) in the northern tropical Atlantic and weakens the meridional heat transport from the tropics to the mid-latitude through an anomalous southward western boundary current. The anomalous STC transports cold HCA from the subtropics to the mid-latitudes, weakening the mid-latitude deep overturning.

  5. Influences of tropical-extratropical interaction on the multidecadal AMOC variability in the NCEP climate forecast system

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohua; Schneider, Edwin K.; Klinger, Barry [Gorge Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Institute of Global Environment and Society, Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Hu, Zeng-Zhen; Xue, Yan [National Centers for Environmental Prediction/NOAA, Climate Prediction Center, Camp Springs, MD (United States); Wu, Zhaohua [Florida State University, Department of Earth, Ocean, and Atmospheric Science, Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL (United States)

    2012-08-15

    We have examined the mechanisms of a multidecadal oscillation of the Atlantic Meridional Overturning Circulation (AMOC) in a 335-year simulation of the Climate Forecast System (CFS), the climate prediction model developed at the National Centers for Environmental Prediction (NCEP). Both the mean and seasonal cycle of the AMOC in the CFS are generally consistent with observation-based estimates with a maximum northward volume transport of 16 Sv (10{sup 6} m{sup 3}/s) near 35 N at 1.2 km. The annual mean AMOC shows an intermittent quasi 30-year oscillation. Its dominant structure includes a deep anomalous overturning cell (referred to as the anomalous AMOC) with amplitude of 0.6 Sv near 35 N and an anomalous subtropical cell (STC) of shallow overturning spanning across the equator. The mechanism for the oscillation includes a positive feedback between the anomalous AMOC and surface wind stress anomalies in mid-latitudes and a negative feedback between the anomalous STC and AMOC. A strong AMOC is associated with warm sea surface temperature anomaly (SSTA) centered near 45 N, which generates an anticyclonic easterly surface wind anomaly. This anticyclonic wind anomaly enhances the regional downwelling and reinforces the anomalous AMOC. In the mean time, a wind-evaporation-SST (WES) feedback extends the warm SSTA to the tropics and induces a cyclonic wind stress anomaly there, which drives a tropical upwelling and weakens the STC north of the equator. The STC anomaly, in turn, drives a cold upper ocean heat content anomaly (HCA) in the northern tropical Atlantic and weakens the meridional heat transport from the tropics to the mid-latitude through an anomalous southward western boundary current. The anomalous STC transports cold HCA from the subtropics to the mid-latitudes, weakening the mid-latitude deep overturning. (orig.)

  6. Possible Causes of Total Ozone Depletion over the Qinghai-Xizang Plateau and Its Relation to Tropopause Height in Recent 30 Years%近30年青藏高原臭氧总量亏损的可能原因及其与对流层顶高度的联系

    Institute of Scientific and Technical Information of China (English)

    周顺武; 杨双艳; 张人禾; 李慧; 王美蓉

    2012-01-01

    基于总臭氧测绘光谱计TOMS和太阳向后紫外线散射仪SBUV结合得到的30年(1979-2008年)全球月平均臭氧总量资料,首先分析了近30年青藏高原(下称高原)上空臭氧总量的下降趋势,然后讨论了高原动力抬升作用对臭氧总量的影响,最后探讨了高原臭氧总量亏损与高原对流层顶高度的联系。结果表明,高原臭氧总量及其下降趋势均存在着明显的季节差异,与同纬度非高原区相比,高原地区各月的臭氧总量均偏低,特别是在3-9月臭氧亏损严重;近30年高原地区臭氧总量在各季节均呈现出下降趋势,除了秋季外,其下降幅度均超过同纬度其他地区;春、夏季高原动力抬升有利于对流层低浓度的臭氧含量向平流层输送,从而导致高原臭氧总量的减少。近30年春、夏季高原臭氧总量亏损与夏季高原第二对流层顶高度的抬升存在着密切关系。%Using the monthly total ozone data from the Total Ozone Mapping Spectrometer and the Solar Backscatter Ultraviolet Radiometer from 1979to 2008,the total ozone depletion over the Qinghai-Xizang Plateau is revealed,and the influences of the terrain lifting activities on total ozone are discussed.Finally,the influence of the total ozone depletion on the lifting at tropopause height of the Qinghai-Xizang Plateau is analyzed.The results suggest that there are significant seasonal differences both total ozone over the Qinghai-Xizang Plateau and its declining trend.What′s more,comparing with the same latitude but nomountain region,the total ozone amount over the Qinghai-Xizang Plateau is lower in each month,especially from March to September.The lose is serious.In recently 30 years,the total ozone over the QinghaiXizang Plateau declines in each season and the decline range is larger than no-mountain region except for autumn.The strong upward movement over the Qinghai-Xizang Plateau in spring and summer is conducive to transport the low

  7. Satellite observations of cirrus clouds in the Northern Hemisphere lowermost stratosphere

    Directory of Open Access Journals (Sweden)

    R. Spang

    2014-05-01

    Full Text Available Here we present observations of the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA of cirrus cloud and water vapour in August 1997 in the upper troposphere and lower stratosphere (UTLS region. The observations indicate a considerable flux of moisture from the upper tropical troposphere into the extra-tropical lowermost stratosphere (LMS, resulting in the occurrence of high altitude optically thin cirrus clouds in the LMS. The locations of the LMS cloud events observed by CRISTA are consistent with the tropopause height determined from coinciding radiosonde data. For a hemispheric analysis in tropopause relative coordinates an improved tropopause determination has been applied to the ECMWF temperature profiles. We found that a significant fraction of the cloud occurrences in the tropopause region are located in the LMS, even if a conservative overestimate of the cloud top height (CTH determination by CRISTA of 500 m is assumed. The results show rather high occurrence frequencies (∼5% up to high northern latitudes (70° N and altitudes well above the tropopause (>500 m at ∼350 K and above in large areas at mid and high latitudes. Comparisons with model runs of the Chemical Lagragian Model of the Stratosphere (CLaMS over the CRISTA period show a reasonable consistency for the retrieved cloud pattern. For this purpose a limb ray tracing approach was applied through the 3-D model fields to obtain integrated measurement information through the atmosphere along the limb path of the instrument. The simplified cirrus scheme implemented in CLaMS seems to cause a systematic underestimation in the CTH occurrence frequencies in the LMS with respect to the observations. The observations together with the model results demonstrate the importance of isentropic, quasi-horizontal transport of water vapour from the sub-tropics and the potential for the occurrence of cirrus clouds in the lowermost stratosphere and tropopause region.

  8. Sediment Transport Processes in a West-central Florida Open Marine Marsh Tidal Creek; the Role of Tides and Extra-tropical Storms

    Science.gov (United States)

    Leonard, Lynn A.; Hine, Albert C.; Luther, Mark E.; Stumpf, Richard P.; Wright, Eric E.

    1995-08-01

    The extensive open marine marshes on Florida's Gulf of Mexico coast constitute one of the largest continuous coastal marsh systems in the U.S.A. and are characterized by (1) the absence of an apparent modern or relict sediment supply, (2) a thin 1-2 m sediment veneer overlying highly karstified bedrock and (3) both low wave and low tidal energy regimes. More importantly, the Florida open marine marsh system appears to be keeping pace with current rates of sea-level rise in spite of a limited inorganic sediment supply and low tidal energies. Although the magnitudes and directions of suspended solid transport and the processes controlling these transports have been rigorously documented for other U.S.A. marsh systems, they have not been documented in the Florida marsh system. Total suspended solid (TSS) concentrations, current speeds and water levels were monitored in Cedar Creek, Florida, so that the TSS loads could be calculated and the processes exerting control over material exchange could be determined. Both TSS concentration and load are modulated by spring/neap variations and time-velocity asymmetries in the tidal currents. Concentrations at the creek mouth increase by as much as two orders of magnitude during strong wind events due to the presence of waves; however, large net sediment loads appear to be related to the coupled effects of waves and large tidal prisms. Waves initially mobilize sediments in the adjacent embayment but increased tidal prisms, and the associated higher velocities, are requisite for transport of this material further into the creek. Large tidal prisms may be the result of astronomically high tides or meteorologically forced tides. In Cedar Creek, the most important meteorological events affecting sedimentary processes are extra-tropical storms. This is because they occur at much higher frequencies than tropical storms and hurricanes, even though the latter are more potent and potentially could transport greater amounts of material

  9. Horizontal Variability of Water and Its Relationship to Cloud Fraction near the Tropical Tropopause: Using Aircraft Observations of Water Vapor to Improve the Representation of Grid-scale Cloud Formation in GEOS-5

    Science.gov (United States)

    Selkirk, Henry B.; Molod, Andrea M.

    2014-01-01

    Large-scale models such as GEOS-5 typically calculate grid-scale fractional cloudiness through a PDF parameterization of the sub-gridscale distribution of specific humidity. The GEOS-5 moisture routine uses a simple rectangular PDF varying in height that follows a tanh profile. While below 10 km this profile is informed by moisture information from the AIRS instrument, there is relatively little empirical basis for the profile above that level. ATTREX provides an opportunity to refine the profile using estimates of the horizontal variability of measurements of water vapor, total water and ice particles from the Global Hawk aircraft at or near the tropopause. These measurements will be compared with estimates of large-scale cloud fraction from CALIPSO and lidar retrievals from the CPL on the aircraft. We will use the variability measurements to perform studies of the sensitivity of the GEOS-5 cloud-fraction to various modifications to the PDF shape and to its vertical profile.

  10. The Relative Frequency of Rossby Wave Train Triggering Mechanisms Associated with Downstream Development Over Europe

    Science.gov (United States)

    2014-06-01

    diabatic Rossby vortices. 14. SUBJECT TERMS Rossby wave train, downstream development, tropopause polar vortex, warm conveyor belt, diabatic Rossby...extratropical transition of tropical cyclones, and six (16%) by diabatic Rossby vortices. vi THIS PAGE INTENTIONALLY LEFT BLANK vii TABLE OF CONTENTS...9  3.  Diabatic Rossby Vortex .....................................................................12  4.  Extratropical

  11. Impact of the Assimilation of Hyperspectral Infrared Retrieved Profiles on Advanced Weather and Research Model Simulations of a Non-Convective Wind Event

    Science.gov (United States)

    Berndt, E. B.; Zavodsky, B. T.; Folmer, M. J.; Jedlovec, G. J.

    2014-01-01

    Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), 32-km North American Regional Reanalysis (NARR) interpolated to a 12-km grid, and 13-km Rapid Refresh analyses.

  12. Photochemistry and aerosol in alpine region: mixing and transport; Photochimie et aerosol en region alpine: melange et transport

    Energy Technology Data Exchange (ETDEWEB)

    Chaxel, E

    2006-11-15

    The Alpine arc deeply interacts with general circulation of atmosphere. By studying configurations in summer and winter over various Alpine areas, this work explains how mixing and transport of airborne pollutants happen, both gaseous and particulate matter, from their emission sources to free troposphere. Using observational results and a comprehensive Eulerian modelling system, one focuses on mechanisms of pollution by ozone in summer and by particulate matter and benzene in winter. After having validated the modelling system using datasets from field experiments POVA, GRENOPHOT and ESCOMPTE, it is applied on two periods with principal interest in the Grenoble area: one is the heat-wave August 2003 and the other is a long episode of thermal inversion in February 2005. Uncertainties are also calculated. One finishes by applying the modelling chain to understand how a stratospheric intrusion following a tropopause fold affected the Alpine region in July 2004. (author)

  13. Vertical transport rates and concentrations of OH and Cl radicals in the Tropical Tropopause Layer from observations of CO2 and halocarbons: implications for distributions of long- and short-lived chemical species

    Directory of Open Access Journals (Sweden)

    T. P. Bui

    2010-07-01

    Full Text Available Rates for large-scale vertical transport of air in the Tropical Tropopause Layer (TTL were determined using high-resolution, in situ observations of CO2 concentrations in the tropical upper troposphere and lower stratosphere during the NASA Tropical Composition, Cloud and Climate Coupling (TC4 campaign in August 2007. Upward movement of trace gases in the deep tropics was notably slower in TC4 than during the Costa Rica AURA Validation Experiment (CR-AVE, in January 2006. Transport rates in the TTL were combined with in situ measurements of chlorinated and brominated organic compounds from whole air samples to determine chemical loss rates for reactive chemical species, providing empirical vertical profiles for 24-h mean concentrations of hydroxyl radicals (OH and chlorine atoms in the TTL. The analysis shows that important short-lived species such as CHCl3, CH2Cl2, and CH2Br2 have longer chemical lifetimes than the time for transit of the TTL, implying that these species, which are not included in most models, could readily reach the stratosphere and make significant contributions of chlorine and/or bromine to stratospheric loading.

  14. Vertical transport rates and concentrations of OH and Cl radicals in the Tropical Tropopause Layer from Observations of CO2 and halocarbons: implications for distributions of long- and short-lived chemical species

    Directory of Open Access Journals (Sweden)

    T. P. Bui

    2010-03-01

    Full Text Available Rates for large-scale vertical transport of air in the Tropical Tropopause Layer (TTL were determined using high-resolution, in situ observations of CO2 concentrations in the tropical upper troposphere and lower stratosphere during the NASA Tropical Composition, Cloud and Climate Coupling (TC4 campaign in August 2007. Upward movement of trace gases in the deep tropics was notably slower in TC4 than during the Costa Rica AURA Validation Experiment (CR-AVE, in January 2006. Transport rates in the TTL were combined with in situ measurements of chlorinated and brominated organic compounds from whole air samples to determine chemical loss rates for reactive chemical species, providing empirical vertical profiles for 24-h mean concentrations of hydroxyl radicals (OH and chlorine atoms in the TTL. The analysis shows that important short-lived species such as CHCl3, CH2Cl2, and CH2Br2 have longer chemical lifetimes than the time for transit of the TTL, implying that these species, which are not included in most models, could readily reach the stratosphere and make significant contributions of chlorine and/or bromine to stratospheric loading.

  15. Cyclogenesis Frequency Changes of Extratropical Cyclones in the Northern Hemisphere and East Asia Revealed by ERA40 Reanalysis Data%ERA40再分析资料揭示的北半球和东亚地区温带气旋生成频率变化

    Institute of Scientific and Technical Information of China (English)

    张颖娴; 丁一汇; 李巧萍

    2012-01-01

    本文利用欧洲中心再分析数据ERA40的6小时间隔海平面气压场和一种改进的客观判定和追踪方法研究1958—2001年北半球和东亚地区温带气旋生成频率的气候态、年代际变化及可能原因。结果表明:(1)北半球温带气旋的源地主要位于北美东部(落基山下游地区)、西北大西洋地区、格陵兰至欧洲北部地区、蒙古地区和日本至西北太平洋地区。大洋的西岸和陡峭地形的背风坡有利于大气斜压性的增强和正涡度的发展,从而有利于地面气旋的形成。(2)年、冬季和春季30°~60°N气旋生成数目呈现减少的变化趋势,60°~90°N地区的气旋生成数呈增加的变化趋势。这在一定程度上支持了北半球风暴路径北移的观点。60°N以南和以北的温带气旋数目同北极涛动指数(AO)分别呈现负相关和正相关,这种相关性在年、春季和秋季最为显著。(3)1958--2001年东亚地区的年气旋数目呈现明显的年代际变化。20世纪60年代至80年代中期40°~60°N、80°~140°E地区气旋数目呈增加趋势,而80年代中期之后温带气旋数目则锐减,主要原因是80年代以后该地区大气斜压性减弱,更高纬度地区的大气斜压性增强,从而导致了气旋源地的北移。在较低纬带的20°~40°N、110°~160°E地区气旋数目线性增加,这主要是由于位于40°~55°N的北太平洋风暴轴有向低纬度偏移的变化趋势造成的。%A climatology of cyclogenesis frequency of extratropical cyclones in the Northern Hemisphere and East Asia for the years of 1958 to 2001, and the interdecadal variation and possible causes, were ana- lyzed by applying an improved objective detecting and tracking algorithm to the six-hourly sea-level pres- sure fields in the European Center for Medium-range Weather Forecasts reanalysis data ERA40. The result shows that: (1) major source regions of

  16. Corrigendum to "A novel downscaling technique for the linkage of global and regional air quality modeling" published in Atmos. Chem. Phys., 9, 9169–9185, 2009

    Directory of Open Access Journals (Sweden)

    Y. F. Lam

    2010-04-01

    Full Text Available Recently, downscaling global atmospheric model outputs (GCTM for the USEPA Community Multiscale Air Quality (CMAQ Initial (IC and Boundary Conditions (BC have become practical because of the rapid growth of computational technologies that allow global simulations to be completed within a reasonable time. The traditional method of generating IC/BC by profile data has lost its advocates due to the weakness of the limited horizontal and vertical variations found on the gridded boundary layers. Theoretically, high quality GCTM IC/BC should yield a better result in CMAQ. Unfortunately, several researchers have found that the outputs from GCTM IC/BC are not necessarily better than profile IC/BC due to the excessive transport of O3 aloft in GCTM IC/BC. In this paper, we intend to investigate the effects of using profile IC/BC and global atmospheric model data. In addition, we are suggesting a novel approach to resolve the existing issue in downscaling.

    In the study, we utilized the GEOS-Chem model outputs to generate time-varied and layer-varied IC/BC for year 2002 with the implementation of tropopause determining algorithm in the downscaling process (i.e., based on chemical (O3 tropopause definition. The comparison between the implemented tropopause approach and the profile IC/BC approach is performed to demonstrate improvement of considering tropopause. It is observed that without using tropopause information in the downscaling process, unrealistic O3 concentrations are created at the upper layers of IC/BC. This phenomenon has caused over-prediction of surface O3 in CMAQ. In addition, the amount of over-prediction is greatly affected by temperature and latitudinal location of the study domain. With the implementation of the algorithm, we have successfully resolved the incompatibility issues in the vertical layer structure between global and regional chemistry models to yield better surface O3

  17. Simulating Turbulent Wind Fields for Offshore Turbines in Hurricane-Prone Regions (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Damiani, R.; Musial, W.

    2014-04-01

    Extreme wind load cases are one of the most important external conditions in the design of offshore wind turbines in hurricane prone regions. Furthermore, in these areas, the increase in load with storm return-period is higher than in extra-tropical regions. However, current standards have limited information on the appropriate models to simulate wind loads from hurricanes. This study investigates turbulent wind models for load analysis of offshore wind turbines subjected to hurricane conditions. Suggested extreme wind models in IEC 61400-3 and API/ABS (a widely-used standard in oil and gas industry) are investigated. The present study further examines the wind turbine response subjected to Hurricane wind loads. Three-dimensional wind simulator, TurbSim, is modified to include the API wind model. Wind fields simulated using IEC and API wind models are used for an offshore wind turbine model established in FAST to calculate turbine loads and response.

  18. Studying the impact of overshooting convection on the tropopause tropical layer (TTL) water vapor budget at the continental scale using a mesoscale model

    Science.gov (United States)

    Behera, Abhinna; Rivière, Emmanuel; Marécal, Virginie; Claud, Chantal; Rysman, Jean-François; Geneviève, Seze

    2016-04-01

    Water vapour budget is a key component in the earth climate system. In the tropical upper troposphere, lower stratosphere (UTLS), it plays a central role both on the radiative and the chemical budget. Its abundance is mostly driven by slow ascent above the net zero radiative heating level followed by ice crystals' formation and sedimentation, so called the cold trap. In contrast to this large scale temperature driven process, overshooting convection penetrating the stratosphere could be one piece of the puzzle. It has been proven to hydrate the lower stratosphere at the local scale. Satellite-borne H2O instruments can not measure with a fine enough resolution the water vapour enhancements caused by overshooting convection. The consequence is that it is difficult to estimate the role of overshooting deep convection at the global scale. Using a mesoscale model i.e., Brazilian Regional Atmospheric Modelling System (BRAMS), past atmospheric conditions have been simulated for the full wet season i.e., Nov 2012 to Mar 2013 having a single grid with horizontal resolution of 20 km × 20km over a large part of Brazil and South America. This resolution is too coarse to reproduce overshooting convection in the model, so that this simulation should be used as a reference (REF) simulation, without the impact of overshooting convection in the TTL water budget. For initialisation, as well as nudging the grid boundary in every 6 hours, European Centre for Medium-Range Weather Forecasts (ECMWF) analyses has been used. The size distribution of hydrometeors and number of cloud condensation nuclei (CCN) are fitted in order to best reproduce accumulated precipitations derived from Tropical Rainfall Measuring Mission (TRMM). Similarly, GOES and MSG IR mages have been thoroughly compared with model's outputs, using image correlation statistics for the position of the clouds. The model H2O variability during the wet season, is compared with the in situ balloon-borne measurements during

  19. Climate impact of volcanic aerosol in the stratosphere and upper troposphere - CALIPSO observations from 2006-2015

    Science.gov (United States)

    Friberg, Johan; Martinsson, Bengt G.; Andersson, Sandra M.; Sandvik, Oscar S.; Hermann, Markus; van Velthoven, Peter F. J.; Zahn, Andreas

    2017-04-01

    We have investigated the climate impact of volcanic eruptions in the period 2006-2015, and found that the volcanic perturbations of the stratospheric aerosol is stronger and lasts longer than previously thought. Recent studies (Ridley et al., 2014, Andersson et al., 2015) show that a large portion of volcanic climate impact stems from aerosol in the LMS (lowermost stratosphere). Although the LMS holds >40% of the stratospheric mass (Appenzeller et al., 1996) it is generally neglected in estimations of the stratospheric AOD (aerosol optical depth). In the past decade the stratospheric aerosol load was perturbed by a number of volcanic eruptions. We cover that period by using the CALIPSO level 1b night-time data to study the volcanic influence on the global and regional climate. CALIPSO data were averaged to a resolution of 180 m vertically and 1×1° horizontally, cleaned from ice clouds by means of the depolarization ratio (Vernier et al., 2009), and a method was developed to remove polar stratospheric clouds (PSC). This approach enables identification of aerosol also at low altitudes (currently using 4 km minimum altitude) and in the Antarctic region (60 to 90°S) where PSCs are frequent during winter. In the current study, we estimate the total stratospheric AOD and radiative forcing and find that significant fractions of volcanic aerosol were located below the static tropopause after volcanic eruptions. Volcanic aerosol was generally observed down to the dynamic tropopause, and detected down to potential vorticities of 1.5-2 PVU (almost 1 km below the static tropopause). Hence, the dynamic tropopause was found to better enclose the volcanic aerosol. Furthermore, large concentrations of aerosol from the Kasatochi eruption (Aug 2008) is found to linger in the extratropical UT (upper troposphere) for several months after the eruption. Sulphate-rich volcanic aerosol transported from the LMS may influence cirrus clouds in the extratropical UT, inducing an indirect

  20. Measurements of NO, NOy, N2O, and O3 during SPURT: implications for transport and chemistry in the lowermost stratosphere

    Directory of Open Access Journals (Sweden)

    M. I. Hegglin

    2006-01-01

    Full Text Available We present measurements of NO, NOy, O3, and N2O within the lowermost stratosphere (LMS over Europe obtained during the SPURT project. The measurements cover all seasons between November 2001 and July 2003. They span a broad band of latitudes from 30° N to 75° N and a potential temperature range from 290 to 380 K. The measurements represent a comprehensive data set of these tracers and reveal atmospheric transport processes that influence tracer distributions in the LMS. Median mixing ratios of stratospheric tracers in equivalent latitude-potential temperature coordinates show a clear seasonal cycle related to the Brewer-Dobson circulation, with highest values in spring and lowest values in autumn. Vertical tracer profiles show strong gradients at the extratropical tropopause, suggesting that vertical (cross-isentropic mixing is reduced above the tropopause. Pronounced meridional gradients in the tracer mixing ratios are found on potential temperature surfaces in the LMS. This suggests strongly reduced mixing along isentropes. Concurrent large gradients in static stability in the vertical direction, and of PV in the meridional direction, suggest the presence of a mixing barrier. Seasonal cycles were found in the correlation slopes ΔO3/ΔN2O and ΔNOy/ΔN2O well above the tropopause. Absolute slope values are smallest in spring indicating chemically aged stratospheric air originating from high altitudes and latitudes. Larger values were measured in summer and autumn suggesting that a substantial fraction of air takes a 'short-cut' from the tropical tropopause region into the extratropical LMS. The seasonal change in the composition of the LMS has direct implications for the ozone chemistry in this region. Comparisons of measured NO with the critical NO value at which net ozone production changes from negative to positive, imply ozone production up to 20 K above the local tropopause in spring, up to 30 K in summer, and up to 40 K in autumn

  1. The Influence of Regional SSTs on the Interdecadal Shift of the East Asian Summer Monsoon

    Institute of Scientific and Technical Information of China (English)

    FU Jianjian; LI Shuanglin

    2013-01-01

    East Asia has experienced a significant interdecadal climate shift since the late 1970s.This shift was accompanied by a decadal change of global SST.Previous studies have suggested that the decadal shift of global SST background status played a substantial role in such a climatic shift.However,the individual roles of different regional SSTs remain unclear.In this study,we investigated these roles using ensemble experiments of an atmospheric general circulation model,GFDL (Geophysical Fluid Dynamics Laboratory) AM2.Two kinds of ensembles were performed.The first was a control ensemble in which the model was driven with the observed climatological SSTs.The second was an experimental ensemble in which the model was driven with the observed climatological SSTs plus interdecadal SST background shifts in separate ocean regions.The results suggest that the SST shift in the tropics exerted more important influence than those in the extratropics,although the latter contribute to the shift modestly.The variations of summer monsoonal circulation systems,including the South Asian High,the West Pacific Subtropical High,and the lower-level air flow,were analyzed.The results show that,in comparison with those induced by extratropical SSTs,the shifts induced by tropical SSTs bear more similarity to the observations and to the simulations with global SSTs prescribed.In particular,the observed SST shift in the tropical Pacific Ocean,rather than the Indian Ocean,contributed significantly to the shift of East Asian summer monsoon since the 1970s.

  2. Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM

    Science.gov (United States)

    Dogar, Muhammad Mubashar; Kucharski, Fred; Azharuddin, Syed

    2017-03-01

    ENSO is considered as a strong atmospheric teleconnection that has pronounced global and regional circulation effects. It modifies global monsoon system, especially, Asian and African monsoons. Previous studies suggest that both the frequency and magnitude of ENSO events have increased over the last few decades resulting in a need to study climatic impacts of ENSO magnitude both at global and regional scales. Hence, to better understand the impact of ENSO amplitude over the tropical and extratropical regions focussing on the Asian and African domains, ENSO sensitivity experiments are conducted using ICTPAGCM (`SPEEDY'). It is anticipated that the tropical Pacific SST forcing will be enough to produce ENSO-induced teleconnection patterns; therefore, the model is forced using NINO3.4 regressed SST anomalies over the tropical Pacific only. SPEEDY reproduces the impact of ENSO over the Pacific, North and South America and African regions very well. However, it underestimates ENSO teleconnection patterns and associated changes over South Asia, particularly in the Indian region, which suggests that the tropical Pacific SST forcing is not sufficient to represent ENSO-induced teleconnection patterns over South Asia. Therefore, SST forcing over the tropical Indian Ocean together with air-sea coupling is also required for better representation of ENSO-induced changes in these regions. Moreover, results obtained by this pacemaker experiment show that ENSO impacts are relatively stronger over the Inter-Tropical Convergence Zone (ITCZ) compared to extratropics and high latitude regions. The positive phase of ENSO causes weakening in rainfall activity over African tropical rain belt, parts of South and Southeast Asia, whereas, the La Niña phase produces more rain over these regions during the summer season. Model results further reveal that ENSO magnitude has a stronger impact over African Sahel and South Asia, especially over the Indian region because of its significant impact

  3. Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM

    Indian Academy of Sciences (India)

    Muhammad Mubashar Dogar; Fred Kucharski; Syed Azharuddin

    2017-03-01

    ENSO is considered as a strong atmospheric teleconnection that has pronounced global and regional circulation effects. It modifies global monsoon system, especially, Asian and African monsoons. Previous studies suggest that both the frequency and magnitude of ENSO events have increased over the last fewdecades resulting in a need to study climatic impacts of ENSO magnitude both at global and regional scales. Hence, to better understand the impact of ENSO amplitude over the tropical and extratropical regions focussing on the Asian and African domains, ENSO sensitivity experiments are conducted using ICTPAGCM (‘SPEEDY’). It is anticipated that the tropical Pacific SST forcing will be enough to produce ENSO-induced teleconnection patterns; therefore, the model is forced using NINO3.4 regressed SST anomalies over the tropical Pacific only. SPEEDY reproduces the impact of ENSO over the Pacific, North and South America and African regions very well. However, it underestimates ENSO teleconnectionpatterns and associated changes over South Asia, particularly in the Indian region, which suggests that the tropical Pacific SST forcing is not sufficient to represent ENSO-induced teleconnection patterns over South Asia. Therefore, SST forcing over the tropical Indian Ocean together with air–sea coupling is alsorequired for better representation of ENSO-induced changes in these regions. Moreover, results obtained by this pacemaker experiment show that ENSO impacts are relatively stronger over the Inter-Tropical Convergence Zone (ITCZ) compared to extratropics and high latitude regions. The positive phase ofENSO causes weakening in rainfall activity over African tropical rain belt, parts of South and Southeast Asia, whereas, the La Ni˜na phase produces more rain over these regions during the summer season. Model results further reveal that ENSO magnitude has a stronger impact over African Sahel and South Asia, especially over the Indian region because of its significant

  4. Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM

    KAUST Repository

    Dogar, Muhammad Mubashar

    2017-03-09

    ENSO is considered as a strong atmospheric teleconnection that has pronounced global and regional circulation effects. It modifies global monsoon system, especially, Asian and African monsoons. Previous studies suggest that both the frequency and magnitude of ENSO events have increased over the last few decades resulting in a need to study climatic impacts of ENSO magnitude both at global and regional scales. Hence, to better understand the impact of ENSO amplitude over the tropical and extratropical regions focussing on the Asian and African domains, ENSO sensitivity experiments are conducted using ICTPAGCM (‘SPEEDY’). It is anticipated that the tropical Pacific SST forcing will be enough to produce ENSO-induced teleconnection patterns; therefore, the model is forced using NINO3.4 regressed SST anomalies over the tropical Pacific only. SPEEDY reproduces the impact of ENSO over the Pacific, North and South America and African regions very well. However, it underestimates ENSO teleconnection patterns and associated changes over South Asia, particularly in the Indian region, which suggests that the tropical Pacific SST forcing is not sufficient to represent ENSO-induced teleconnection patterns over South Asia. Therefore, SST forcing over the tropical Indian Ocean together with air–sea coupling is also required for better representation of ENSO-induced changes in these regions. Moreover, results obtained by this pacemaker experiment show that ENSO impacts are relatively stronger over the Inter-Tropical Convergence Zone (ITCZ) compared to extratropics and high latitude regions. The positive phase of ENSO causes weakening in rainfall activity over African tropical rain belt, parts of South and Southeast Asia, whereas, the La Niña phase produces more rain over these regions during the summer season. Model results further reveal that ENSO magnitude has a stronger impact over African Sahel and South Asia, especially over the Indian region because of its significant

  5. SOWER (Soundings of Ozone and Water in the Equatorial Region): Overview and Highlights

    Science.gov (United States)

    Hasebe, F.; Shiotani, M.; Fujiwara, M.; Shibata, T.; Inai, Y.

    2014-12-01

    The Soundings of Ozone and Water in the Equatorial Region (SOWER) has been accumulating observational evidences of atmospheric dehydration taking place in the Tropical Tropopause Layer (TTL) since initiation in 1998. SOWER data successfully characterize the nature of TTL dehydration in which the cold-trap is effectively functioning between 360 K and 380 K isentropes while some moistening taking place before the air parcel reaches 400 K. The first attempts of the TTL water vapor 'match' suggest the threshold of nucleation being 146 ± 19 % in relative humidity with respect to ice with the typical dehydration time scale of about an hour in the lower TTL. Simultaneous observations by lidar and Optical Particle Counters near the cold point tropopause reveale cirrus clouds within the aerosol layer composed of liquid phase aqueous sulfuric acid particles. The estimated concentrations of cloud particles and aerosols are not consistent with the interpretation of cloud formation in liquid phase aerosol particles. In February 2014, a series of ozone (ECC) and water vapor (CFH) sonde observations was conducted at Biak (1.2oS, 136.1oE) collaborating with LAPAN, Indonesia. The sea surface temperature in the western tropical Pacific showed positive anomalies. The convective activities were relatively low in the eastern Indian Ocean to the Maritime Continent, while an eastward propagation of active convection associated with intraseasonal oscillation was observed. This campaign was not simply an extension of the previous ones, but was intended to provide correlative data for ATTREX/CONTRAST/CAST aircraft campaigns. Unfortunately the coordination did not run as originally intended. A sequence of independent sonde data, however, may provide some useful information for airborne observations. This paper presents an overview of the project and introduces the highlights of the findings obtained.

  6. Climatic variability of river outflow in the Pantanal region and the influence of sea surface temperature

    Science.gov (United States)

    Silva, Carlos Batista; Silva, Maria Elisa Siqueira; Ambrizzi, Tércio

    2016-03-01

    This paper investigates possible linear relationships between climate, hydrology, and oceanic surface variability in the Pantanal region (in South America's central area), over interannual and interdecadal time ranges. In order to verify the mentioned relations, lagged correlation analysis and linear adjustment between river discharge at the Pantanal region and sea surface temperature were used. Composite analysis for atmospheric fields, air humidity flux divergence, and atmospheric circulation at low and high levels, for the period between 1970 and 2003, was analyzed. Results suggest that the river discharge in the Pantanal region is linearly associated with interdecadal and interannual oscillations in the Pacific and Atlantic oceans, making them good predictors to continental hydrological variables. Considering oceanic areas, 51 % of the annual discharge in the Pantanal region can be linearly explained by mean sea surface temperature (SST) in the Subtropical North Pacific, Tropical North Pacific, Extratropical South Pacific, and Extratropical North Atlantic over the period. Considering a forecast approach in seasonal scale, 66 % of the monthly discharge variance in Pantanal, 3 months ahead of SST, is explained by the oceanic variables, providing accuracy around 65 %. Annual discharge values in the Pantanal region are strongly related to the Pacific Decadal Oscillation (PDO) variability (with 52 % of linear correlation), making it possible to consider an interdecadal variability and a consequent subdivision of the whole period in three parts: 1st (1970-1977), 2nd (1978-1996), and 3rd (1997-2003) subperiods. The three subperiods coincide with distinct PDO phases: negative, positive, and negative, respectively. Convergence of humidity flux at low levels and the circulation pattern at high levels help to explain the drier and wetter subperiods. During the wetter 2nd subperiod, the air humidity convergence at low levels is much more evident than during the other two

  7. The 2014 southeast Brazil austral summer drought: regional scale mechanisms and teleconnections

    Science.gov (United States)

    Coelho, Caio A. S.; de Oliveira, Cristiano Prestrelo; Ambrizzi, Tércio; Reboita, Michelle Simões; Carpenedo, Camila Bertoletti; Campos, José Leandro Pereira Silveira; Tomaziello, Ana Carolina Nóbile; Pampuch, Luana Albertani; Custódio, Maria de Souza; Dutra, Lívia Marcia Mosso; Da Rocha, Rosmeri P.; Rehbein, Amanda

    2016-06-01

    The southeast region of Brazil experienced in austral summer 2014 a major drought event leading to a number of impacts in water availability for human consumption, agricultural irrigation and hydropower production. This study aims to perform a diagnostic analysis of the observed climate conditions during this event, including an inspection of the occurred precipitation anomalies in the context of previous years, and an investigation of possible relationships with sea surface temperatures and atmospheric circulation patterns. The sea surface temperature analysis revealed that the southwestern South Atlantic Ocean region near the coast of southeast Brazil showed strong negative association with precipitation over southeast Brazil, indicating that increased sea temperatures in this ocean region are consistent with reduced precipitation as observed in summer 2014. The circulation analysis revealed prevailing anti-cyclonic anomalies at lower levels (850 hPa) with northerly anomalies to the west of southeast Brazil, channeling moisture from the Amazon towards Paraguay, northern Argentina and southern Brazil, and drier than normal air from the South Atlantic Ocean towards the southeast region of Brazil. This circulation pattern was found to be part of a large-scale teleconnection wave train linked with the subsidence branch of the Walker circulation in the tropical east Pacific, which in turn was generated by an anomalous tropical heat source in north/northeastern Australia. A regional Hadley circulation with an ascending branch to the south of the subsidence branch of the Walker circulation in the tropical east Pacific was identified as an important component connecting the tropical and extratropical circulation. The ascending branch of this Hadley circulation in the south Pacific coincided with an identified Rossby wave source region, which contributed to establishing the extratropical component of the large-scale wave train connecting the south Pacific and the Atlantic

  8. Climatic variability of river outflow in the Pantanal region and the influence of sea surface temperature

    Science.gov (United States)

    Silva, Carlos Batista; Silva, Maria Elisa Siqueira; Ambrizzi, Tércio

    2017-07-01

    This paper investigates possible linear relationships between climate, hydrology, and oceanic surface variability in the Pantanal region (in South America's central area), over interannual and interdecadal time ranges. In order to verify the mentioned relations, lagged correlation analysis and linear adjustment between river discharge at the Pantanal region and sea surface temperature were used. Composite analysis for atmospheric fields, air humidity flux divergence, and atmospheric circulation at low and high levels, for the period between 1970 and 2003, was analyzed. Results suggest that the river discharge in the Pantanal region is linearly associated with interdecadal and interannual oscillations in the Pacific and Atlantic oceans, making them good predictors to continental hydrological variables. Considering oceanic areas, 51 % of the annual discharge in the Pantanal region can be linearly explained by mean sea surface temperature (SST) in the Subtropical North Pacific, Tropical North Pacific, Extratropical South Pacific, and Extratropical North Atlantic over the period. Considering a forecast approach in seasonal scale, 66 % of the monthly discharge variance in Pantanal, 3 months ahead of SST, is explained by the oceanic variables, providing accuracy around 65 %. Annual discharge values in the Pantanal region are strongly related to the Pacific Decadal Oscillation (PDO) variability (with 52 % of linear correlation), making it possible to consider an interdecadal variability and a consequent subdivision of the whole period in three parts: 1st (1970-1977), 2nd (1978-1996), and 3rd (1997-2003) subperiods. The three subperiods coincide with distinct PDO phases: negative, positive, and negative, respectively. Convergence of humidity flux at low levels and the circulation pattern at high levels help to explain the drier and wetter subperiods. During the wetter 2nd subperiod, the air humidity convergence at low levels is much more evident than during the other two

  9. Discussing the role of tropical and subtropical moisture sources in extreme precipitation events in the Mediterranean region from a climate change perspective

    Directory of Open Access Journals (Sweden)

    S. O. Krichak

    2015-06-01

    Full Text Available Extreme precipitation events in the Mediterranean region during the cool season are strongly affected by the export of moist air from tropical and subtropical areas into the extratropics. The aim of this paper is to present a discussion of the major research efforts on this subject and to formulate a summary of our understanding of this phenomenon, along with its recent past trends from a climate change perspective. The issues addressed are: a discussion of several case studies; the origin of the air moisture and the important role of atmospheric rivers for fueling the events; the mechanism responsible for the intensity of precipitation during the events, and the possible role of global warming in recent past trends in extreme weather events over the Mediterranean region.

  10. Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and South-East Asia during 2009-2013

    Science.gov (United States)

    Wisher, A.; Oram, D. E.; Laube, J. C.; Mills, G. P.; van Velthoven, P.; Zahn, A.; Brenninkmeijer, C. A. M.

    2013-11-01

    Short-lived organic brominated compounds make up a significant part (~20%) of the organic bromine budget in the atmosphere. Emissions of these compounds are highly variable and there are limited measurements, particularly in the extra-tropical upper troposphere/lower stratosphere and tropical troposphere. Measurements of five short-lived bromomethanes (VSLB) were made in air samples collected on the CARIBIC project aircraft over three flight routes; Germany to Venezuela/Columbia during 2009-2011, Germany to South Africa during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during 2012 and 2013. In the tropical troposphere, as the most important entrance region to the stratosphere, we observe a total mean organic bromine derived from these compounds across all flights at 10-12 km altitude of 3.4 ± 1.5 ppt. Individual mean tropical tropospheric mixing ratios across all flights were 0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The highest levels of VSLS-derived bromine (4.20 ± 0.56 ppt) were observed in flights between Bangkok and Kuala Lumpur indicating that the South China Sea is an important source region for these compounds. Across all routes, CHBr3 and CH2Br2 accounted for 34% (4.7-71) and 48% (14-73) respectively of total bromine derived from the analysed VSLB in the tropical mid-upper troposphere totalling 82% (54-89). In samples collected between Germany and Venezuela/Columbia, we find decreasing mean mixing ratios with increasing potential temperature in the extra-tropics. Tropical mean mixing ratios are higher than extra-tropical values between 340-350 K indicating that rapid uplift is important in determining mixing ratios in the lower tropical tropopause layer in the West Atlantic tropics. O3 was used as a tracer for stratospherically influenced air and we detect rapidly decreasing mixing ratios for all VSLB above ~100 ppb O3 corresponding to the extra-tropical tropopause layer.

  11. Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and Southeast Asia during 2009-2013

    Science.gov (United States)

    Wisher, A.; Oram, D. E.; Laube, J. C.; Mills, G. P.; van Velthoven, P.; Zahn, A.; Brenninkmeijer, C. A. M.

    2014-04-01

    Short-lived organic brominated compounds make up a significant part of the organic bromine budget in the atmosphere. Emissions of these compounds are highly variable and there are limited measurements, particularly in the extra-tropical upper troposphere/lower stratosphere and tropical troposphere. Measurements of five very short-lived bromomethanes (VSLB) were made in air samples collected on the CARIBIC project aircraft over three flight routes; Germany to Venezuela/Columbia during 2009-2011, Germany to South Africa during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during 2012 and 2013. In the tropical troposphere, as the most important entrance region to the stratosphere, we observe a total mean organic bromine derived from these compounds across all flights at 10-12 km altitude of 3.4 ± 1.5 ppt. Individual mean tropical tropospheric mixing ratios across all flights were 0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The highest levels of VSLB-derived bromine (4.20 ± 0.56 ppt) were observed in flights between Bangkok and Kuala Lumpur indicating that the South China Sea is an important source region for these compounds. Across all routes, CHBr3 and CH2Br2 accounted for 34% (4.7-71) and 48% (14-73) respectively of total bromine derived from the analysed VSLB in the tropical mid-upper troposphere totalling 82% (54-89). In samples collected between Germany and Venezuela/Columbia, we find decreasing mean mixing ratios with increasing potential temperature in the extra-tropics. Tropical mean mixing ratios are higher than extra-tropical values between 340-350 K indicating that rapid uplift is important in determining mixing ratios in the lower tropical tropopause layer in the West Atlantic tropics. O3 was used as a tracer for stratospherically influenced air and we detect rapidly decreasing mixing ratios for all VSLB above ∼100 ppb O3 corresponding to the extra-tropical tropopause layer.

  12. Regional Competition in Maghreb Region

    Institute of Scientific and Technical Information of China (English)

    EL AMOURI ALLAL

    2016-01-01

    Great powers focus on cooperation instead of competition in their regions in order to maintain stability and develop the economy of their regions and the world in general. The United States for example created the North American Free Trade Agreement (NAFT

  13. Africa Region

    African Journals Online (AJOL)

    Impact of HIV/AIDS on» Gross Domestic Product (GGP) in the WHO. Africa Region ... methods) and for economic evaluations of treatment, prevention and promotion. , programmes. ..... develop new products), for which we could not find data ...

  14. Regional odontodysplasia.

    Science.gov (United States)

    Mehta, D N; Bailoor, D; Patel, B

    2011-01-01

    Regional odontodysplasia is an unusual developmental anomaly in which ectodermal and mesodermal tooth components are affected. We present a rare case of a developmental anomaly called regional odontodysplasia or 'ghost teeth' in a 12-year-old Indian girl. The anomaly affected right maxillary permanent teeth. The mandibular teeth were unaffected. The clinical, radiographic and histological features are reviewed. The management of affected patients is discussed.

  15. Regional odontodysplasia

    Directory of Open Access Journals (Sweden)

    D N Mehta

    2011-01-01

    Full Text Available Regional odontodysplasia is an unusual developmental anomaly in which ectodermal and mesodermal tooth components are affected. We present a rare case of a developmental anomaly called regional odontodysplasia or ′ghost teeth′ in a 12-year-old Indian girl. The anomaly affected right maxillary permanent teeth. The mandibular teeth were unaffected. The clinical, radiographic and histological features are reviewed. The management of affected patients is discussed.

  16. Indirect Radiative Forcing and Climatic Effect of the Anthropogenic Nitrate Aerosol on Regional Climate of China

    Institute of Scientific and Technical Information of China (English)

    LI Shu; WANG Wijian; ZHUANG Bingliang; HAN Yong

    2009-01-01

    The regional climate model (RegCM3) and a tropospheric atmosphere chemistry model (TACM) were couplcd, thus a regional climate chemistry modeling system (RegCCMS) was constructed, which was applied to investigate the spatial distribution of anthropogenic nitrate aerosols, indirect radiative forcing, as well as its climatic effect over China. TACM includes the thermodynamic equilibrium model ISORROPIA and a condensed gas-phase chemistry model. Investigations show that the concentration of nitrate aerosols is relatively high over North and East China with a maximum of 29μg m-3 in January and 8 μg m-3 in July.Due to the influence of air temperature on thermodynamic equilibrium, wet scavenging of precipitation and the monsoon climate, there are obvious seasonal differences in nitrate concentrations. The average indirect radiative forcing at the tropopause due to nitrate aerosols is -1.63 W m-2 in January and -2.65 W m-2 in July, respectively. In some areas, indirect radiative forcing reaches -10 W m-2. Sensitivity tests show that nitrate aerosols make the surface air temperature drop and the precipitation reduce on the national level. The mean changes in surface air temperature and precipitation are -0.13 K and -0.01 mm d-1 in January and -0.09 K and -0.11 mm d-1 in July, respectively, showing significant differences in different regions.

  17. Lengthening of the growing season in wheat and maize producing regions

    Directory of Open Access Journals (Sweden)

    Brigitte Mueller

    2015-09-01

    Full Text Available Human-induced increases in atmospheric greenhouse gas concentrations have led to rising global temperatures. Here we investigate changes in an annual temperature-based index, the growing season length, defined as the number of days with temperature above 5 °C. We show that over extratropical regions where wheat and maize are harvested, the increase in growing season length from 1956 to 2005 can be attributed to increasing greenhouse gas concentrations. Our analyses also show that climate change has increased the probability of extremely long growing seasons by a factor of 25, and decreased the probability of extremely short growing seasons. A lengthening of the growing season in regions with these mostly rain-fed crops could improve yields, provided that water availability does not become an issue. An expansion of areas with more than 150 days of growing season into the northern latitudes makes more land potentially available for planting wheat and maize. Furthermore, double-cropping can become an alternative to current practices in areas with very long growing seasons which are also shown to increase with a warming climate. These results suggest that there is a strong impact of anthropogenic climate change on growing season length. However, in some regions and with further exacerbated climate change, high temperatures may already be or may become a limiting factor for plant productivity.

  18. Regional Wave Climates along Eastern Boundary Currents

    Science.gov (United States)

    Semedo, Alvaro; Soares, Pedro

    2016-04-01

    Two types of wind-generated gravity waves coexist at the ocean surface: wind sea and swell. Wind sea waves are waves under growing process. These young growing waves receive energy from the overlaying wind and are strongly coupled to the local wind field. Waves that propagate away from their generation area and no longer receive energy input from the local wind are called swell. Swell waves can travel long distances across entire ocean basins. A qualitative study of the ocean waves from a locally vs. remotely generation perspective is important, since the air sea interaction processes is strongly modulated by waves and vary accordingly to the prevalence of wind sea or swell waves in the area. A detailed climatology of wind sea and swell waves along eastern boundary currents (EBC; California Current, Canary Current, in the Northern Hemisphere, and Humboldt Current, Benguela Current, and Western Australia Current, in the Southern Hemisphere), based on the ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis will be presented. The wind regime along EBC varies significantly from winter to summer. The high summer wind speeds along EBC generate higher locally generated wind sea waves, whereas lower winter wind speeds in these areas, along with stronger winter extratropical storms far away, lead to a predominance of swell waves there. In summer, the coast parallel winds also interact with coastal headlands, increasing the wind speed through a process called "expansion fan", which leads to an increase in the height of locally generated waves downwind of capes and points. Hence the spatial patterns of the wind sea or swell regional wave fields are shown to be different from the open ocean along EBC, due to coastal geometry and fetch dimensions. Swell waves will be shown to be considerably more prevalent and to carry more energy in winter along EBC, while in summer locally generated wind sea waves are either more comparable to swell waves or

  19. Filamentary structure in chemical tracer distributions near the subtropical jet following a wave breaking event

    Directory of Open Access Journals (Sweden)

    J. Ungermann

    2013-10-01

    Full Text Available This paper presents a set of observations and analyses of trace gas cross sections in the extratropical upper troposphere/lower stratosphere (UTLS. The spatially highly resolved (≈0.5 km vertically and 12.5 km horizontally cross sections of ozone (O3, nitric acid (HNO3, and peroxyacetyl nitrate (PAN, retrieved from the measurements of the CRISTA-NF infrared limb sounder flown on the Russian M55-Geophysica, revealed intricate layer structures in the region of the subtropical tropopause break. The chemical structure in this region shows an intertwined stratosphere and troposphere. The observed filaments in all discussed trace gases are of a spatial scale of less than 0.8 km vertically and about 200 km horizontally across the jet stream. Backward trajectory calculations confirm that the observed filaments are the result of a breaking Rossby wave in the preceding days. An analysis of the trace gas relationships between PAN and O3 identifies four distinct groups of air mass: polluted subtropical tropospheric air, clean tropical upper-tropospheric air, the lowermost stratospheric air, and air from the deep stratosphere. The tracer relationships further allow the identification of tropospheric, stratospheric, and the transitional air mass made of a mixture of UT and LS air. Mapping of these air mass types onto the geo-spatial location in the cross sections reveals a highly structured extratropical transition layer (ExTL. Finally, the ratio between the measured reactive nitrogen species (HNO3 + PAN + ClONO2 and O3 is analysed to estimate the influence of tropospheric pollution on the extratropical UTLS. In combination, these diagnostics provide the first example of a multi-species two-dimensional picture of the inhomogeneous distribution of chemical species within the UTLS region. Since Rossby wave breaking occurs frequently in the region of the tropopause break, these observed fine-scale filaments are likely ubiquitous in the region. The

  20. Filamentary structure in chemical tracer distributions near the subtropical jet following a wave breaking event

    Directory of Open Access Journals (Sweden)

    J. Ungermann

    2013-02-01

    Full Text Available This paper presents a set of observations and analyses of trace gas cross-sections in the extratropical upper troposphere/lower stratosphere (UTLS. The spatially highly-resolved (≈0.5 km vertically and 12.5 km horizontally cross-sections of ozone (O3, nitric acid (HNO3, and peroxyacetyl nitrate (PAN, retrieved from the measurements of the CRISTA-NF infrared limb sounder flown on the Russian M55-Geophysica, revealed intricate layer structures in the region of the subtropical tropopause break. The chemical structure in this region shows an intertwined stratosphere and troposphere. The observed filaments in all discussed trace gases are of a spatial scale of less than 0.8 km vertically and about 200 km horizontally across the jet-stream. Backward trajectory calculations confirm that the observed filaments are the result of a breaking Rossby wave in the preceding days. An analysis of the trace gas relationships between PAN and O3 identifies four distinct groups of air mass: polluted subtropical tropospheric air, clean tropical upper-tropospheric air, the lowermost stratospheric air, and air from the deep stratosphere. The tracer relationships further allow the identification of tropospheric, stratospheric, and the transitional air mass made of a mixture of UT and LS air. Mapping of these air mass types onto the geo-spatial location in the cross-sections reveals a highly structured extratropical transition layer (ExTL. Finally, the ratio between the measured reactive nitrogen species (HNO3 + PAN + ClONO2 and O3 is analysed to estimate the influence of tropospheric pollution on the extratropical UTLS.

    In combination, these diagnostics provide the first example of a multi-species two-dimensional picture of a chemically inhomogeneous UTLS region. Since Rossby wave breaking occurs frequently in the region of the tropopause break, these observed fine scale filaments are

  1. Planetary wave signatures in the equatorial atmosphere ionosphere system, and mesosphere- E- and F-region coupling

    Science.gov (United States)

    Abdu, M. A.; Ramkumar, T. K.; Batista, I. S.; Brum, C. G. M.; Takahashi, H.; Reinisch, B. W.; Sobral, J. H. A.

    2006-02-01

    Upward transport of wave energy and momentum due to gravity, tidal and planetary waves from below and extra-tropics controls the phenomenology of the equatorial atmosphere ionosphere system. An important aspect of this phenomenology is the development of small- and large-scale structures including thin layers in the mesosphere and E-region, and the formation of wide spectrum plasma structures of the equatorial F-region, widely known as equatorial spread F/plasma bubble irregularities (that are known to have significant impact on space application systems based on trans-ionospheric radio waves propagation). It seems that the effects of tidal and gravity waves at mesospheric and thermospheric heights and their control of ionospheric densities, electric fields and currents are relatively better known than are the effects originating from vertical coupling due to planetary waves. Results from airglow, radar and ionospheric sounding observations demonstrate the existence of significant planetary wave influence on plasma parameters at E- and F-region heights over equatorial latitudes. We present and discuss here some results showing planetary wave oscillations in concurrent mesospheric winds and equatorial electrojet intensity variations in the Indian sector as well as in the mesospheric airglow and F-layer height variation in Brazil. Also presented are evidences of planetary wave-scale oscillations in equatorial evening pre-reversal electric field (F-region vertical drift) and their effects on equatorial spread F /plasma bubble irregularity development and day-to-day variability.

  2. Regional odontodysplasia

    Directory of Open Access Journals (Sweden)

    Thimma Reddy B

    2010-01-01

    Full Text Available Regional odontodysplasia (ROD is a rare developmental anomaly involving both mesodermal and ectodermal components in a group of contiguous teeth. It affects the primary and permanent dentitions in the maxilla and the mandible or both, however, the maxilla is frequently involved. Although the etiology of the ROD is uncertain, it has been suggested that numerous other factors play a role. The treatment plan should be based on the degree of involvement as well as the functional and esthetic needs in each case. This article reports the case of a 5-year-old boy presenting a rare anomaly on the right side of the maxillary arch. The treatment performed was rehabilitation with temporary partial acrylic denture and periodic checkups. The extraction was followed by rehabilitation with dental implants. The main aim of this article is to provide valuable information to pediatric dentists about the review and treatment alternatives for ROD.

  3. Observations of PAN and its confinement in the Asian Monsoon Anticyclone in high spatial resolution

    Science.gov (United States)

    Ungermann, Joern; Ploeger, Felix; Spang, Reinhold; Riese, Martin

    2016-04-01

    This talk presents a set of observations by the CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) infrared limb sounder on the SPAS platform in low-earth orbit. The spatially highly resolved trace gas measurements of six days in August 1997 allow a close look on the confinement of air masses within the Asian Summer Monsoon (ASM) anticyclone. Peroxyacetyl nitrate (PAN) is a secondary pollutant without sources in the stratosphere and acts as a tropospheric tracer. In combination with ozone as a stratospheric tracer, an eddy-shedding event of the ASM could be observed. The measured PAN volume mixing ratios (VMR) correlate well with potential vorticity (PV) derived from ECMWF ERA-Interim model data. Computing the gradient of PAN over PV on isentropes reveals that PAN VMR exhibit the strongest decrease at each isentrope for an increasing value of PV, which may be used to identify the extent of the ASM on that isentrope. CRISTA measurements also provide the temperature of measured air parcels and thus allow to derive the location of the thermal tropopause. We find that the thermal tropopause coincides with the border of the positive PAN anomaly both horizontally and vertically within the ASM anticyclone. In contrast, the shed eddy exhibits enhanced PAN VMRs for 1 to 2 km above the thermal tropopause. The amount of mixing may also be characterised by projecting the derived air parcels into tracer-tracer space using PAN and ozone as tropospheric and stratospheric tracer, respectively. This reveals that the anticyclone contains few mixed parcels in contrast to the region between the anticyclone and the shed eddy. This implies that while the anticyclone confines polluted air masses well, eddy shedding provides a very rapid horizontal transport pathway of Asian pollution into the extratropical lowermost stratosphere with a time scale of only a few days.

  4. Comparison of the CMAM30 data set with ACE-FTS and OSIRIS: polar regions

    Directory of Open Access Journals (Sweden)

    D. Pendlebury

    2015-04-01

    Full Text Available CMAM30 is a 30 year data set extending from 1979 to 2010 that is generated using a version of the Canadian Middle Atmosphere Model (CMAM in which the winds and temperatures are relaxed to the Interim Reanalysis product from the European Centre Medium-Range for Weather Forecasts (ERA-Interim. The data set has dynamical fields that are very close to the reanalysis below 1 hPa and chemical tracers that are self-consistent with respect to the model winds and temperature. The chemical tracers are expected to be close to actual observations. The data set is here compared to two satellite records – the Atmospheric Chemistry Experiment Fourier Transform Spectometer and the Odin Optical Spectrograph and InfraRed Imaging System – for the purpose of validating the temperature, ozone, water vapour and methane fields. Data from the Aura Microwave Limb Sounder is also used for validation of the chemical processing in the polar vortex. It is found that the CMAM30 temperature is warm by up to 5 K in the stratosphere, with a low bias in the mesosphere of ~ 5–15 K. Ozone is reasonable (± 15% except near the tropopause globally, and in the Southern Hemisphere winter polar vortex. Water vapour is consistently low by 10–20%, with corresponding high methane of 10–20%, except in the Southern Hemisphere polar vortex. Discrepancies in this region are shown to stem from the treatment of polar stratospheric cloud formation in the model.

  5. Regional cooling caused recent New Zealand glacier advances in a period of global warming

    Science.gov (United States)

    Mackintosh, Andrew N.; Anderson, Brian M.; Lorrey, Andrew M.; Renwick, James A.; Frei, Prisco; Dean, Sam M.

    2017-02-01

    Glaciers experienced worldwide retreat during the twentieth and early twenty first centuries, and the negative trend in global glacier mass balance since the early 1990s is predominantly a response to anthropogenic climate warming. The exceptional terminus advance of some glaciers during recent global warming is thought to relate to locally specific climate conditions, such as increased precipitation. In New Zealand, at least 58 glaciers advanced between 1983 and 2008, and Franz Josef and Fox glaciers advanced nearly continuously during this time. Here we show that the glacier advance phase resulted predominantly from discrete periods of reduced air temperature, rather than increased precipitation. The lower temperatures were associated with anomalous southerly winds and low sea surface temperature in the Tasman Sea region. These conditions result from variability in the structure of the extratropical atmospheric circulation over the South Pacific. While this sequence of climate variability and its effect on New Zealand glaciers is unusual on a global scale, it remains consistent with a climate system that is being modified by humans.

  6. Regional and global sea-surface temperatures during the last interglaciation.

    Science.gov (United States)

    Hoffman, Jeremy S; Clark, Peter U; Parnell, Andrew C; He, Feng

    2017-01-20

    The last interglaciation (LIG, 129 to 116 thousand years ago) was the most recent time in Earth's history when global mean sea level was substantially higher than it is at present. However, reconstructions of LIG global temperature remain uncertain, with estimates ranging from no significant difference to nearly 2°C warmer than present-day temperatures. Here we use a network of sea-surface temperature (SST) records to reconstruct spatiotemporal variability in regional and global SSTs during the LIG. Our results indicate that peak LIG global mean annual SSTs were 0.5 ± 0.3°C warmer than the climatological mean from 1870 to 1889 and indistinguishable from the 1995 to 2014 mean. LIG warming in the extratropical latitudes occurred in response to boreal insolation and the bipolar seesaw, whereas tropical SSTs were slightly cooler than the 1870 to 1889 mean in response to reduced mean annual insolation. Copyright © 2017, American Association for the Advancement of Science.

  7. Regional cooling caused recent New Zealand glacier advances in a period of global warming.

    Science.gov (United States)

    Mackintosh, Andrew N; Anderson, Brian M; Lorrey, Andrew M; Renwick, James A; Frei, Prisco; Dean, Sam M

    2017-02-14

    Glaciers experienced worldwide retreat during the twentieth and early twenty first centuries, and the negative trend in global glacier mass balance since the early 1990s is predominantly a response to anthropogenic climate warming. The exceptional terminus advance of some glaciers during recent global warming is thought to relate to locally specific climate conditions, such as increased precipitation. In New Zealand, at least 58 glaciers advanced between 1983 and 2008, and Franz Josef and Fox glaciers advanced nearly continuously during this time. Here we show that the glacier advance phase resulted predominantly from discrete periods of reduced air temperature, rather than increased precipitation. The lower temperatures were associated with anomalous southerly winds and low sea surface temperature in the Tasman Sea region. These conditions result from variability in the structure of the extratropical atmospheric circulation over the South Pacific. While this sequence of climate variability and its effect on New Zealand glaciers is unusual on a global scale, it remains consistent with a climate system that is being modified by humans.

  8. Regional cooling caused recent New Zealand glacier advances in a period of global warming

    Science.gov (United States)

    Mackintosh, Andrew N.; Anderson, Brian M.; Lorrey, Andrew M.; Renwick, James A.; Frei, Prisco; Dean, Sam M.

    2017-01-01

    Glaciers experienced worldwide retreat during the twentieth and early twenty first centuries, and the negative trend in global glacier mass balance since the early 1990s is predominantly a response to anthropogenic climate warming. The exceptional terminus advance of some glaciers during recent global warming is thought to relate to locally specific climate conditions, such as increased precipitation. In New Zealand, at least 58 glaciers advanced between 1983 and 2008, and Franz Josef and Fox glaciers advanced nearly continuously during this time. Here we show that the glacier advance phase resulted predominantly from discrete periods of reduced air temperature, rather than increased precipitation. The lower temperatures were associated with anomalous southerly winds and low sea surface temperature in the Tasman Sea region. These conditions result from variability in the structure of the extratropical atmospheric circulation over the South Pacific. While this sequence of climate variability and its effect on New Zealand glaciers is unusual on a global scale, it remains consistent with a climate system that is being modified by humans. PMID:28195582

  9. Development of Distributed Research Center for analysis of regional climatic and environmental changes

    Science.gov (United States)

    Gordov, E.; Shiklomanov, A.; Okladnikov, I.; Prusevich, A.; Titov, A.

    2016-11-01

    We present an approach and first results of a collaborative project being carried out by a joint team of researchers from the Institute of Monitoring of Climatic and Ecological Systems, Russia and Earth Systems Research Center UNH, USA. Its main objective is development of a hardware and software platform prototype of a Distributed Research Center (DRC) for monitoring and projecting of regional climatic and environmental changes in the Northern extratropical areas. The DRC should provide the specialists working in climate related sciences and decision-makers with accurate and detailed climatic characteristics for the selected area and reliable and affordable tools for their in-depth statistical analysis and studies of the effects of climate change. Within the framework of the project, new approaches to cloud processing and analysis of large geospatial datasets (big geospatial data) inherent to climate change studies are developed and deployed on technical platforms of both institutions. We discuss here the state of the art in this domain, describe web based information-computational systems developed by the partners, justify the methods chosen to reach the project goal, and briefly list the results obtained so far.

  10. Impact of freeze-drying, mixing and horizontal transport on water vapor in the upper troposphere and lower stratosphere (UTLS)

    Science.gov (United States)

    Poshyvailo, Liubov; Ploeger, Felix; Müller, Rolf; Tao, Mengchu; Konopka, Paul; Abdoulaye Diallo, Mohamadou; Grooß, Jens-Uwe; Günther, Gebhard; Riese, Martin

    2017-04-01

    Water vapor in the upper troposphere and lower stratosphere (UTLS) is a key player in the global radiation budget. Therefore, a realistic representation of the water vapor distribution in this region and the involved control processes is critical for climate models, but largely uncertain hitherto. It is known that the extremely low temperatures around the tropical tropopause cause the dominant factor controlling water vapor in the lower stratosphere. Here, we focus on additional processes, such as horizontal transport between tropics and extratropics, small-scale mixing, and freeze-drying. We assess the sensitivities of simulated water vapor in the UTLS from simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS). CLaMS is a Lagrangian transport model, with a parameterization of small-scale mixing (model diffusion) which is coupled to deformations in the large-scale flow. First, to assess the robustness of water vapor with respect to the meteorological datasets we examine CLaMS driven by ECMWF ERA-Interim and the Japanese 55-year reanalysis. Second, to investigate the effects of small-scale mixing we vary the parameterized mixing strength in the CLaMS model between the reference case with the mixing strength optimized to reproduce atmospheric trace gas observations and a purely advective simulation with parameterized mixing turned off. Also calculation of Lagrangian cold points gives further insight of the processes involved. Third, to assess the effects of horizontal transport between the tropics and extratropics we carry out sensitivity simulations with horizontal transport barriers along latitude circles at the equator, 15°N/S and 35°N/S. Finally, the impact of Antarctic dehydration is estimated from additional sensitivity simulations with switched off freeze-drying in the model at high latitudes of 50°N/S. Our results show that the uncertainty in the tropical tropopause temperatures between current reanalysis datasets causes significant

  11. A PBL-radiation model for application to regional numerical weather prediction

    Science.gov (United States)

    Chang, Chia-Bo

    1989-01-01

    Often in the short-range limited-area numerical weather prediction (NWP) of extratropical weather systems the effects of planetary boundary layer (PBL) processes are considered secondarily important. However, it may not be the case for the regional NWP of mesoscale convective systems over the arid and semi-arid highlands of the southwestern and south-central United States in late spring and summer. Over these dry regions, the PBL can grow quite high up into the lower middle troposphere (600 mb) due to very effective solar heating and hence a vigorous air-land thermal interaction can occur. The interaction representing a major heat source for regional dynamical systems can not be ignored. A one-dimensional PBL-radiation model was developed. The model PBL consists of a constant-flux surface layer superposed with a well-mixed (Ekman) layer. The vertical eddy mixing coefficients for heat and momentum in the surface layer are determined according to the surface similarity theory, while their vertical profiles in the Ekman layer are specified with a cubic polynomial. Prognostic equations are used for predicting the height of the nonneutral PBL. The atmospheric radiation is parameterized to define the surface heat source/sink for the growth and decay of the PBL. A series of real-data numerical experiments has been carried out to obtain a physical understanding how the model performs under various atmospheric and surface conditions. This one-dimensional model will eventually be incorporated into a mesoscale prediction system. The ultimate goal of this research is to improve the NWP of mesoscale convective storms over land.

  12. Scaling from Flux Towers to Ecosystem Models: Regional Constraints on GPP from Atmospheric Carbonyl Sulfide

    Science.gov (United States)

    Abu-Naser, M.; Campbell, J.; Berry, J. A.; Seibt, U.; Maseyk, K. S.; Torn, M. S.; Biraud, S. C.; Fischer, M. L.; Billesbach, D. P.; Baker, I. T.; Collatz, G. J.; Chen, H.; Montzka, S. A.; Sweeney, C.

    2012-12-01

    Process-level information on terrestrial carbon fluxes are typically observed at small spatial scales (e.g. eddy flux towers) but critical applications exist at much larger spatial scales (e.g. global ecosystem models). New methodologies are needed to fill this spatial gap. Recent work suggests that analysis of atmospheric carbonyl sulfide (COS) could fill this gap by providing constraints on GPP fluxes at large scales. This proposal is based on evidence that COS plant uptake is quantitatively related to photosynthesis and that COS plant uptake is the dominant COS budget flux influencing atmospheric concentrations over northern extratropical continents. Previous atmospheric analysis of COS has focused on continental or larger scales and only one ecosystem model. Here we explore the spatial and temporal COS variation within North America and their relationship to a range of ecosystem models using regional and global atmospheric transport models. Airborne COS observations are examined from the NOAA-ESRL network including 13 North American airborne sites and a total of 1,447 vertical profiles from years 2004 to 2012. In addition to COS plant uptake, we examined the influence of atmospheric transport treatments, boundary conditions, soil fluxes (mechanistic and empirical), and anthropogenic emissions. The atmospheric COS simulations were consistent with the primary observed spatial and temporal variations in the US mid-continent. This consistency is supportive of ecosystem models because the dominant input for these atmospheric COS simulations is ecosystem model GPP data. However, only the COS simulations driven by a subset of the ecosystem models were able to reproduce the observed COS seasonality in a semiarid cultivated region (ARM/SGP). This subset of ecosystem models produced GPP seasonality that was similar to eddy flux estimates, suggesting a role for COS observations in extending flux tower data to regional spatial scales.

  13. Desenvolvimento regional: a diversidade regional como potencialidade

    Directory of Open Access Journals (Sweden)

    José Odim Degrandi

    2013-04-01

    Full Text Available Throughout the second half of the twentieth century the debate on regional development in Brazil received special attention, especially among economists and geographers. Two main approaches stand out in the debate: one that understands the promotion of regional development from the reduction / elimination of regional inequalities, and the other proposes the understanding of regional diversity and potentiality for developing regions. The first was and still remains hegemonic, being evidenced both in scientific papers and in documents guiding public policies in the area. The latter is evidenced most clearly from the 1990s on, a period when the concept of region is resumed under a new approach. This paper aims to clarify the meaning of each of these concepts in order to contribute to the qualification of the discussion on regional development.

  14. Desenvolvimento regional: a diversidade regional como potencialidade

    Directory of Open Access Journals (Sweden)

    Virginia Elisabeta Etges

    2013-03-01

    Full Text Available Ao longo da segunda metade do século XX o debate sobre desenvolvimento regional no Brasil recebeu atenção especial, principalmente, entre economistas e geógrafos. Dois enfoques principais se destacam no debate: um, que entende a promoção do desenvolvimento regional a partir da redução/eliminação das desigualdades regionais; outro, que propõe a compreensão da diversidade regional como potencialidade para o desenvolvimento de regiões. O primeiro foi e continua sendo hegemônico, evidenciado tanto em trabalhos científicos quanto em documentos norteadores das políticas públicas na área. Já o segundo evidencia-se mais claramente a partir da década de 1990, período em que o conceito de região é retomado sob um novo enfoque. Neste trabalho pretende-se explicitar o significado de cada uma dessas concepções, no intuito de contribuir para a qualificação da discussão sobre desenvolvimento regional.Palavras-chave | Desenvolvimento regional; diversidade regional; potencialidades; região.Código JEL | O18; R11; R58. REGIONAL DEVELOPMENT: REGIONAL DIVERSITY AS POTENTIALAbstractThroughout the second half of the twentieth century the debate on regional development in Brazil received special attention, especially among economists and geographers. Two main approaches stand out in the debate: one that understands the promotion of regional development from the reduction / elimination of regional inequalities, and the other proposes the understanding of regional diversity and potentiality for developing regions. The first was and still remains hegemonic, being evidenced both in scientific papers and in documents guiding public policies in the area. The latter is evidenced most clearly from the 1990s on, a period when the concept of region is resumed under a new approach. This paper aims to clarify the meaning of each of these concepts in order to contribute to the qualification of the discussion on regional development.Keywords | Regional

  15. Variability of ozone near the tropopause from GASP data

    Science.gov (United States)

    Nastrom, G. D.

    1978-01-01

    The first 22 months of ozone data from the Global Atmospheric Sampling Program are summarized. Variations in space and time were examined at nearly all scales permitted by the data. Case studies in the tropics suggest that local ozone maxima may be found in or near clouds. Preliminary seasonal mean maps of ozone during spring are presented for the Northern Hemisphere. In the troposphere over the United States during summer there is a distinct midcontinental ozone maximum. There is a diurnal variation in ozone in the upper troposphere and the daily range is about 5 ppbv. Correlations between ozone and other variables are given for the synoptic-scale and on a hemispheric scale. The possible bearing of these results on ozone transport computations is discussed.

  16. Consistent regional fluxes of CH4 and CO2 inferred from GOSAT proxy XCH4 : XCO2 retrievals, 2010-2014

    Science.gov (United States)

    Feng, Liang; Palmer, Paul I.; Bösch, Hartmut; Parker, Robert J.; Webb, Alex J.; Correia, Caio S. C.; Deutscher, Nicholas M.; Domingues, Lucas G.; Feist, Dietrich G.; Gatti, Luciana V.; Gloor, Emanuel; Hase, Frank; Kivi, Rigel; Liu, Yi; Miller, John B.; Morino, Isamu; Sussmann, Ralf; Strong, Kimberly; Uchino, Osamu; Wang, Jing; Zahn, Andreas

    2017-04-01

    We use the GEOS-Chem global 3-D model of atmospheric chemistry and transport and an ensemble Kalman filter to simultaneously infer regional fluxes of methane (CH4) and carbon dioxide (CO2) directly from GOSAT retrievals of XCH4 : XCO2, using sparse ground-based CH4 and CO2 mole fraction data to anchor the ratio. This work builds on the previously reported theory that takes into account that (1) these ratios are less prone to systematic error than either the full-physics data products or the proxy CH4 data products; and (2) the resulting CH4 and CO2 fluxes are self-consistent. We show that a posteriori fluxes inferred from the GOSAT data generally outperform the fluxes inferred only from in situ data, as expected. GOSAT CH4 and CO2 fluxes are consistent with global growth rates for CO2 and CH4 reported by NOAA and have a range of independent data including new profile measurements (0-7 km) over the Amazon Basin that were collected specifically to help validate GOSAT over this geographical region. We find that large-scale multi-year annual a posteriori CO2 fluxes inferred from GOSAT data are similar to those inferred from the in situ surface data but with smaller uncertainties, particularly over the tropics. GOSAT data are consistent with smaller peak-to-peak seasonal amplitudes of CO2 than either the a priori or in situ inversion, particularly over the tropics and the southern extratropics. Over the northern extratropics, GOSAT data show larger uptake than the a priori but less than the in situ inversion, resulting in small net emissions over the year. We also find evidence that the carbon balance of tropical South America was perturbed following the droughts of 2010 and 2012 with net annual fluxes not returning to an approximate annual balance until 2013. In contrast, GOSAT data significantly changed the a priori spatial distribution of CH4 emission with a 40 % increase over tropical South America and tropical Asia and a smaller decrease over Eurasia and temperate

  17. Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data

    Directory of Open Access Journals (Sweden)

    F. Deng

    2013-10-01

    Full Text Available We have examined the utility of retrieved column-averaged, dry-air mole fractions of CO2 (XCO2 from the Greenhouse Gases Observing Satellite (GOSAT for quantifying monthly, regional flux estimates of CO2, using the GEOS-Chem four-dimensional variational (4D-Var data assimilation system. We focused on assessing the potential impact of biases in the GOSAT CO2 data on the regional flux estimates. Using different screening and bias correction approaches, we selected three different subsets of the GOSAT XCO2 data for the 4D-Var inversion analyses, and found that the inferred global fluxes were consistent across the three XCO2 inversions. However, the GOSAT observational coverage was a challenge for the regional flux estimates. In the northern extratropics, the inversions were more sensitive to North American fluxes than to European and Asian fluxes due to the lack of observations over Eurasia in winter and over eastern and southern Asia in summer. The regional flux estimates were also sensitive to the treatment of the residual bias in the GOSAT XCO2 data. The largest differences obtained were for Temperate North America and Temperate South America, for which the largest spread between the inversions was 1.02 Pg C and 0.96 Pg C, respectively. In the case of Temperate North America, one inversion suggested a strong source, whereas the second and third XCO2 inversions produced a weak and strong sink, respectively. Despite the discrepancies in the regional flux estimates between the three XCO2 inversions, the a posteriori CO2 distributions were in good agreement (with a mean difference between the three inversions of typically less than 0.5 ppm with independent data from the Total Carbon Column Observing Network (TCCON, the surface flask network, and from the HIAPER Pole-to-Pole Observations (HIPPO aircraft campaign. The discrepancy in the regional flux estimates from the different inversions, despite the agreement of the global flux estimates, suggests

  18. An early onset of ENSO influence in the extra-tropics of the southwest Pacific inferred from a 14, 600 year high resolution multi-proxy record from Paddy's Lake, northwest Tasmania

    Science.gov (United States)

    Beck, Kristen K.; Fletcher, Michael-Shawn; Gadd, Patricia S.; Heijnis, Henk; Jacobsen, Geraldine E.

    2017-02-01

    Tropical El Niño Southern Oscillation (ENSO) is an important influence on natural systems and cultural change across the Pacific Ocean basin. El Niño events result in negative moisture anomalies in the southwest Pacific and are implicated in droughts and catastrophic wildfires across eastern Australia. An amplification of tropical El Niño activity is reported in the east Pacific after ca. 6.7 ka; however, proxy data for ENSO-driven environmental change in Australia suggest an initial influence only after ca. 5 ka. Here, we reconstruct changes in vegetation, fire activity and catchment dynamics (e.g. erosion) over the last 14.6 ka from part of the southwest Pacific in which ENSO is the main control of interannual hydroclimatic variability: Paddy's Lake, in northwest Tasmania (1065 masl), Australia. Our multi-proxy approach includes analyses of charcoal, pollen, geochemistry and radioactive isotopes. Our results reveal a high sensitivity of the local and regional vegetation to climatic change, with an increase of non-arboreal pollen between ca. 14.6-13.3 ka synchronous with the Antarctic Cold Reversal, and a sensitivity of the local vegetation and fire activity to ENSO variability recorded in the tropical east Pacific through the Holocene. We detect local-scale shifts in vegetation, fire and sediment geochemistry at ca. 6.3, 4.8 and 3.4 ka, simultaneous with increases in El Niño activity in the tropical Pacific. Finally, we observe a fire-driven shift in vegetation from a pyrophobic association dominated by rainforest elements to a pyrogenic association dominated by sclerophyllous taxa following a prolonged (>1 ka) phase of tropical ENSO-amplification and a major local fire event at ca. 3.4 ka. Our results reveal the following key insights: (1) that ENSO has been a persistent modulator of southwest Pacific climate and fire activity through the Holocene; (2) that the climate of northwest Tasmania is sensitive to long-term shifts in tropical ENSO variability; and

  19. Central Region Regionally Ecological Significant Areas

    Data.gov (United States)

    Minnesota Department of Natural Resources — This is an analysis of regionally significant Terrestrial and Wetland Ecological Areas in the seven county metropolitan area. Individual forest, grassland and...

  20. A study of simulation and prediction of extratropical cyclones over the Northern Hemisphere partⅡ:Future changes under RCP4.5 projected by the 6 CMIP5 coupled models%北半球温带气旋的模拟和预估研究Ⅱ∶6个 CMIP5耦合模式预估的未来 RCP4.5情景下的变化

    Institute of Scientific and Technical Information of China (English)

    张颖娴; 丁一汇

    2014-01-01

    The simulation results of the 6 climate coupled models of CMIP5 under the secondary emission scenarion RCP4.5 (Representative Concentration Pathway 4.5)are used to estimate the changes of the extratropical cyclone (EC)numbers and EC intensity,as well as the storm track and its strength in the future.The results indicate that:(1)although each model dif¯ fers in the simulations of the regional cyclogenesis during 2053—2100 under RCP4.5 relative to the second half of the 20th cen¯ tury,it is similarly found that ECs would decrease integrally in the Northern Hemisphere,especially in the lower latitudes.(2) The central pressure of ECs over the Northern Hemisphere would depress and the vorticity intensity would weaken in the future reproduced by models consistently.The simulated Atlantic storm track would move polewards sequentially but with weakened strength as are shown by most of the models in the future;the simulated Pacific storm track would also migrate polewards by more than half the models,but with intensity changes differing in the different seasons.And,(3)a poleward movement of the future baroclinic zone in the middle¯upper troposphere is detected in all the 6 models,and this change in the Southern Hemi¯ sphere would be more significant.The changes of the baroclinic zone reflect the similar changes of storm track to some extent, which supports for the conclusion of possible poleward shift of the two storm tracks.That could be a significant reduction in EC activities over the Northern Hemisphere under RCP4.5,while the poleward movements of baroclinic zone and storm path would cause more remarkable reduction of EC activities over the lower latitudes in the future.%利用 CMIP5(Coupled Model Intercomparison Project Phase 5)的6个气候耦合模式中等排放情景———RCP4•5(典型浓度路径4•5)下的模拟结果对北半球温带气旋数目、风暴路径和强度的未来变化进行了研究分析。结果表明:(1)相对于20

  1. Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

    Directory of Open Access Journals (Sweden)

    F. Ploeger

    2017-06-01

    Full Text Available Pollution transport from the surface to the stratosphere within the Asian monsoon circulation may cause harmful effects on stratospheric chemistry and climate. Here, we investigate air mass transport from the monsoon anticyclone into the stratosphere using a Lagrangian chemistry transport model. We show how two main transport pathways from the anticyclone emerge: (i into the tropical stratosphere (tropical pipe, and (ii into the Northern Hemisphere (NH extratropical lower stratosphere. Maximum anticyclone air mass fractions reach around 5 % in the tropical pipe and 15 % in the extratropical lowermost stratosphere over the course of a year. The anticyclone air mass fraction correlates well with satellite hydrogen cyanide (HCN and carbon monoxide (CO observations, confirming that pollution is transported deep into the tropical stratosphere from the Asian monsoon anticyclone. Cross-tropopause transport occurs in a vertical chimney, but with the pollutants transported quasi-horizontally along isentropes above the tropopause into the tropics and NH.

  2. Climatic variability between SST and river discharge at Amazon region

    Science.gov (United States)

    Silva, M. E.; Silva, E. R. L.

    2012-04-01

    Climatic variability, related both to precipitation and river discharge, has been associated to ocean variability. Authors commonly relate Pacific sea surface temperature (SST) variation to South America (SA) precipitation. Zonal displacement of Walker cell, with intensified subsidence over northern portion of SA, Subtropical Jet strengthening/weakening over extratropical latitudes of SA are, respectively, dynamical reasons scientifically accepted for increasing and depletion of precipitation at the respective areas. Many studies point out the influence of tropical Atlantic SST anomalies in relation to precipitation/river discharge variability over northeast of Brazil. Aliseos variability at tropical Atlantic is also a physic process that contributes to explain precipitation and river flow variability over SA, mainly over the north portion. In this study, we aim to investigate the temporal correlation between SST, mainly from Pacific and Atlantic oceans, and rivers discharge at the Amazon region. Ji-Parana, Madeira and Tapajós river discharge in monthly and annual scale, between 1968 and 2008, were the time series selected to reach the purpose. Time series for river discharge were obtained from Agência Nacional de Águas (ANA, in Portuguese) and, SST data were obtained from CDC/NOAA. Before linear correlation computations between river discharge and SST have been made, seasonal cycle and linear tendency were removed from all original time series. Areas better correlated to river discharge at Amazon region show oceanic patterns apparently associated to PDO (Pacific Decadal Oscillation) and ENSO (El Niño-South Oscillation) variability, with absolute values greater than 0.3 and reaching 0.5 or 0.6. The spatial pattern observed at Pacific basin is similar to that showed by the first mode of PCA (Principal Component Analysis), such seen in many studies (the "horse shoe" pattern). In general, negative correlation values appear far more to the west of Pacific basin

  3. The Regional Dimension

    DEFF Research Database (Denmark)

    Eskjær, Mikkel Fugl

    2013-01-01

    is largely dependent on regional media systems, yet the role this regional dimension plays has been largely overlooked. This article presents a comparative study of climate-change coverage in three geo-cultural regions, The Middle East, Scandinavia, and North America, and explores the link between global...... climate-change communication and regional media systems. It finds that regional variations in climate-change communication carry important communicative implications concerning perceptions of climate change's relevance and urgency...

  4. EVALUATING FUNCTIONAL REGIONS

    Directory of Open Access Journals (Sweden)

    Samo Drobne

    2012-12-01

    Full Text Available In the paper, we suggest an approach to evaluate the number and composition of functional regions. Suggested approach is based on basic characteristics of functional regions, that are (1 more intensive intra-regional than the inter-regional interactions and (2 internal social and economic heterogeneity. Those characteristics are measured by factors estimated in spatial interaction model. The approach to evaluate functional regions was applied to Slovenia for three time periods.

  5. 3-D evaluation of tropospheric ozone simulations by an ensemble of regional Chemistry Transport Model

    Directory of Open Access Journals (Sweden)

    D. Zyryanov

    2011-10-01

    Full Text Available A detailed 3-D evaluation of an ensemble of five regional CTM's and one global CTM with focus on free tropospheric ozone over Europe is presented. It is performed over a summer period (June to August 2008 in the context of the GEMS-RAQ project. A data set of about 400 vertical ozone profiles from balloon soundings and commercial aircraft at 11 different locations is used for model evaluation, in addition to satellite measurements with the infrared nadir IASI sounder showing largest sensitivity to free tropospheric ozone. In the free troposphere, models using the same top and boundary conditions from MOZART-IFS exhibit a systematic negative bias with respect to observed profiles of about −20%. RMSE values are constantly growing with altitude, from 22% to 32% to 53%, respectively for 0–2 km, 2–8 km and 8–10 km height ranges. Lowest correlation is found in the free troposphere, with minimum coefficients (R between 0.2 to 0.45 near 8 km, as compared to 0.7 near the surface and similar values around 10 km. Use of hourly instead of monthly chemical boundary conditions generally improves the model skill. Lower tropospheric 0–6 km partial ozone columns derived from IASI show a clear North-South gradient over Europe, which is qualitatively reproduced by the models. Also the temporal variability showing decreasing ozone concentrations in the lower troposphere (0–6 km columns during summer is well catched by models even if systematic bias remains (the value of the bias being also controlled by the type of BC used. A multi-day case study of a through with low tropopause was conducted and showed that both IASI and models were able to resolve strong horizontal gradients of middle and upper tropospheric ozone occurring in the vicinity of an upper tropospheric frontal zone.

  6. Regional Alternative Transportation Evaluation, Region 6

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Region 6 (Colorado, Kansas, Montana, Nebraska, North Dakota, South Dakota, Utah, and Wyoming) RATE found that visitors to many stations enjoy activities that...

  7. Regional difference of the start time of the recent warming in Eastern China: prompted by a 165-year temperature record deduced from tree rings in the Dabie Mountains

    Science.gov (United States)

    Cai, Qiufang; Liu, Yu; Duan, Bingchuang; Sun, Changfeng

    2017-06-01

    Tree-ring studies from tropical to subtropical regions are rarer than that from extratropical regions, which greatly limit our understanding of some critical climate change issues. Based on the tree-ring-width chronology of samples collected from the Dabie Mountains, we reconstructed the April-June mean temperature for this region with an explained variance of 46.8%. Five cold (1861-1869, 1889-1899, 1913-1920, 1936-1942 and 1952-1990) and three warm (1870-1888, 1922-1934 and 2000-2005) periods were identified in the reconstruction. The reconstruction not only agreed well with the instrumental records in and around the study area, but also showed good resemblance to previous temperature reconstructions from nearby regions, indicating its spatial and temporal representativeness of the temperature variation in the central part of eastern China. Although no secular warming trend was found, the warming trend since 1970 was unambiguous in the Dabie Mountains (0.064 °C/year). Further temperature comparison indicated that the start time of the recent warming in eastern China was regional different. It delayed gradually from north to south, starting at least around 1940 AD in the north part, around 1970 AD in the central part and around 1980s in the south part. This work enriches the high-resolution temperature reconstructions in eastern China. We expect that climate warming in the future would promote the radial growth of alpine Pinus taiwanensis in the subtropical areas of China, therefore promote the carbon capture and carbon storage in the Pinus taiwanensis forest. It also helps to clarify the regional characteristic of recent warming in eastern China.

  8. Region 9 RTOC Charter

    Science.gov (United States)

    U.S. EPA Pacific Southwest (Region 9) Regional Tribal Operations Committee (RTOC) Charter as amended 11/13/2014: Mission, Goals, Scope, Structure & Membership, Meetings, Administration, Charter Amendment/Review, and Current Working Draft.

  9. CONCEPTS OF REGIONALIZATION, REGIONAL SUBSYSTEMS, REGIONAL COMPLEXES AND REGIONAL TRANSFORMATIONS IN CONTEMPORARY IR

    Directory of Open Access Journals (Sweden)

    Alexei D. Voskressenski

    2012-01-01

    Full Text Available Abstract: The article examines theoretical aspects of regional dimension in international relations and the ways to apply in practice the results of world politics’ analysis from the viewpoint of regional and macro-regional levels. It also considers the key discussion points on regions and macro-regions in the world and Russian research literature. The author concludes that this is exactly the new IR concepts of regional level which should become the prototype of original Russian regional and country studies. These studies need to have a higher degree of theoretical conceptualization of regional level as their basis. Such an approach will enable the researchers to draw deep and unconventional conclusions of practical use especially as far as the non-Western parts of the world which are traditionally less examined by Western researchers, theorists and practitioners are concerned.

  10. Drycleaner Database - Region 7

    Data.gov (United States)

    U.S. Environmental Protection Agency — THIS DATA ASSET NO LONGER ACTIVE: This is metadata documentation for the Region 7 Drycleaner Database (R7DryClnDB) which tracks all Region7 drycleaners who notify...

  11. Development of Distributed Research Center for monitoring and projecting regional climatic and environmental changes: first results

    Science.gov (United States)

    Gordov, Evgeny; Shiklomanov, Alexander; Okladinikov, Igor; Prusevich, Alex; Titov, Alexander

    2016-04-01

    Description and first results of the cooperative project "Development of Distributed Research Center for monitoring and projecting of regional climatic and environmental changes" recently started by SCERT IMCES and ESRC UNH are reported. The project is aimed at development of hardware and software platform prototype of Distributed Research Center (DRC) for monitoring and projecting regional climatic and environmental changes over the areas of mutual interest and demonstration the benefits of such collaboration that complements skills and regional knowledge across the northern extratropics. In the framework of the project, innovative approaches of "cloud" processing and analysis of large geospatial datasets will be developed on the technical platforms of two U.S. and Russian leading institutions involved in research of climate change and its consequences. Anticipated results will create a pathway for development and deployment of thematic international virtual research centers focused on interdisciplinary environmental studies by international research teams. DRC under development will comprise best features and functionality of earlier developed by the cooperating teams' information-computational systems RIMS (http://rims.unh.edu) and CLIMATE(http://climate.scert.ru/), which are widely used in Northern Eurasia environment studies. The project includes several major directions of research (Tasks) listed below. 1. Development of architecture and defining major hardware and software components of DRC for monitoring and projecting of regional environmental changes. 2. Development of an information database and computing software suite for distributed processing and analysis of large geospatial data hosted at ESRC and IMCES SB RAS. 3. Development of geoportal, thematic web client and web services providing international research teams with an access to "cloud" computing resources at DRC; two options will be executed: access through a basic graphical web browser and

  12. HRM: HII Region Models

    Science.gov (United States)

    Wenger, Trey V.; Kepley, Amanda K.; Balser, Dana S.

    2017-07-01

    HII Region Models fits HII region models to observed radio recombination line and radio continuum data. The algorithm includes the calculations of departure coefficients to correct for non-LTE effects. HII Region Models has been used to model star formation in the nucleus of IC 342.

  13. Redefining Regional Economic Layout

    Institute of Scientific and Technical Information of China (English)

    Yan Manman

    2010-01-01

    @@ In 2009, the Chinese government approved planning for 9 regional development zones, including plans for the Taiwan Strait West Bank Economic Zone, the Guanzhong-Tianshui Economic Zone, the Jiangsu Coastal Region, the Tumen River Region and Yellow River High-efficient Ecological Economic Zone, among others.

  14. Redefining Regional Economic Layout

    Institute of Scientific and Technical Information of China (English)

    Yan Manman

    2011-01-01

    @@ In 2009, the Chinese government approved planning for 9 regional development zones, including plans for the Taiwan Strait West Bank Economic Zone, the Guanzhong-Tianshui Economic Zone, the Jiangsu Coastal Region, the Tumen River Region and Yellow River High-efficient Ecological Economic Zone, among others.

  15. Balancing Regional Development

    Institute of Scientific and Technical Information of China (English)

    LAN XINZHEN

    2010-01-01

    @@ An early version of a regional economic plan for the Xinjiang Uygur Autonomous Region is under scrutiny by the State Council,China's cabinet.The draft,which could be passed and implemented by May,will focus on the energy,tourism,iron and steel,new agriculture and recycling economy sectors in the autonomous region.

  16. Observations of PAN and its confinement in the Asian summer monsoon anticyclone in high spatial resolution

    Science.gov (United States)

    Ungermann, Jörn; Ern, Mandfred; Kaufmann, Martin; Müller, Rolf; Spang, Reinhold; Ploeger, Felix; Vogel, Bärbel; Riese, Martin

    2016-07-01

    This paper presents an analysis of trace gases in the Asian summer monsoon (ASM) region on the basis of observations by the CRISTA infrared limb sounder taken in low-earth orbit in August 1997. The spatially highly resolved measurements of peroxyacetyl nitrate (PAN) and O3 allow a detailed analysis of an eddy-shedding event of the ASM anticyclone. We identify enhanced PAN volume mixing ratios (VMRs) within the main anticyclone and within the eddy, which are suitable as a tracer for polluted air originating in India and China. Plotting the retrieved PAN VMRs against potential vorticity (PV) and potential temperature reveals that the PV value at which the PAN VMRs exhibit the strongest decrease with respect to PV increases with potential temperature. These PV values might be used to identify the extent of the ASM. Using temperature values also derived from CRISTA measurements, we also computed the location of the thermal tropopause according to the WMO criterion and find that it confines the PAN anomaly vertically within the main ASM anticyclone. In contrast, the shed eddy exhibits enhanced PAN VMRs for 1 to 2 km above the thermal tropopause. Using the relationship between PAN as a tropospheric tracer and O3 as a stratospheric tracer to identify mixed air parcels, we further found the anticyclone to contain few such air parcels, whereas the region between the anticyclone and the eddy as well as the eddy itself contains many mixed air parcels. In combination, this implies that while the anticyclone confines polluted air masses well, eddy shedding provides a very rapid horizontal transport pathway of Asian pollution into the extratropical lowermost stratosphere with a timescale of only a few days.

  17. Local, Regional or Global?

    DEFF Research Database (Denmark)

    Geisler Asmussen, Christian

    This paper proposes a multidimensional index of regional and global orientation which can be used in confirmatory studies with econometric methodologies. Unlike extant measures, the index is objectively scaled and controls for home country orientation and market size differences. The index is shown...... in fact reflects strong home country biases.Keywords: globalization; regional integration; global strategy; regional strategy; local strategy; triad; liability of foreignness...... to be consistent with models of internationalization that incorporate different assumptions about strategic choice and global competition. Preliminary results show that large multinationals follow home region oriented internationalization paths, although much of the regional effect reported by previous studies...

  18. Evaluation of Model Microphysics Within Precipitation Bands of Extratropical Cyclones

    Science.gov (United States)

    Colle, Brian A.; Yu, Ruyi; Molthan, Andrew L.; Nesbitt, Steven

    2014-01-01

    It is hypothesized microphysical predictions have greater uncertainties/errors when there are complex interactions that result from mixed phased processes like riming. Use Global Precipitation Measurement (GPM) Mission ground validation studies in Ontario, Canada to verify and improve parameterizations. The WRF realistically simulated the warm frontal snowband at relatively short lead times (1014 h). The snowband structire is sensitive to the microphysical parameterization used in WRF. The Goddard and SBUYLin most realistically predicted the band structure, but overpredicted snow content. The double moment Morrison scheme best produced the slope of the snow distribution, but it underpredicted the intercept. All schemes and the radar derived (which used dry snow ZR) underpredicted the surface precipitation amount, likely because there was more cloud water than expected. The Morrison had the most cloud water and the best precipitation prediction of all schemes.

  19. A Climatological Study of Hurricane Force Extratropical Cyclones

    Science.gov (United States)

    2012-03-01

    to weaken. There is some indication that diabatic processes serve as an additional energy source. Brief examination of predictability using ECMWF...Shortly after this time, the storm begins to weaken. There is some indication that diabatic processes serve as an additional energy source. Brief...Their primary energy source comes in the form of a baroclinic zone (meridional temperature gradient). While not a necessary ingredient, diabatic

  20. Detection of merger and splitting of extra-tropical cyclones

    Science.gov (United States)

    Kew, Sarah; Hanley, John

    2013-04-01

    Results from the project IMILAST (Intercomparison of mid-latitude storm diagnostics) show that, despite a wide variety in the 15 cyclone identification and tracking techniques considered, a reasonable agreement on tracks of intense cyclones can be reached, at least in the central intensifying stage of the cyclone life cycle. In contrast, diagnostics of cyclone genesis and lysis events show reduced agreement amongst the methods with genesis and lysis density maps exhibiting coherence over smaller spatial scales. Recent work by Hanley and Caballero claims that multi-centre cyclones occur more frequently as storm intensity increases, with an associated increase in the probability of spurious splittings by single-centre tracking routines. We investigate whether the methodological differences in handling of cyclone merger and splitting are responsible for the range in genesis/lysis outcomes exhibited in IMILAST results or whether other factors, such as cyclone definition, have more influence over the spread. The study is focussed on a number of selected cases of intense cyclones that undergo a clear merger or splitting. Of the methods contributing to the IMILAST project, three explicitly handle cyclone merger and splitting. In demonstrating the differences between the techniques, we explore what each approach has to offer.

  1. Evaluation of Model Microphysics Within Precipitation Bands of Extratropical Cyclones

    Science.gov (United States)

    Colle, B.; Molthan, A.; Yu, R.; Stark, D.; Yuter, S. E.; Nesbitt, S. W.

    2013-12-01

    Recent studies evaluating the bulk microphysical schemes (BMPs) within cloud resolving models (CRMs) have indicated large uncertainties and errors in the amount and size distributions of snow and cloud ice aloft. The snow prediction is sensitive to the snow densities, habits, and degree of riming within the BMPs. Improving these BMPs is a crucial step toward improving both weather forecasting and climate predictions. Several microphysical schemes in the Weather Research and Forecasting (WRF) model down to 1.33-km grid spacing are evaluated using aircraft, radar, and ground in situ data from the Global Precipitation Mission Cold-season Precipitation Experiment (GCPEx) experiment, as well as a few years (15 winter storms) of surface measurements of riming, crystal habit, snow density, and radar measurements at Stony Brook, NY (SBNY on north shore of Long Island) during the 2009-2012 winter seasons. Surface microphysical measurements at SBNY were taken every 15 to 30 minutes using a stereo microscope and camera, and snow depth and snow density were also recorded. During these storms, a vertically-pointing Ku-band radar was used to observe the vertical evolution of reflectivity and Doppler vertical velocities. A Particle Size and Velocity (PARSIVEL) disdrometer was also used to measure the surface size distribution and fall speeds of snow at SBNY. For the 15 cases at SBNY, the WSM6, Morrison (MORR), Thompson (THOM2), and Stony Brook (SBU-YLIN) BMPs were validated. A non-spherical snow assumption (THOM2 and SBU-YLIN) simulated a more realistic distribution of reflectivity than spherical snow assumptions in the WSM6 and MORR schemes. The MORR, WSM6, and SBU-YLIN schemes are comparable to the observed velocity distribution in light and moderate riming periods. The THOM2 is ~0.25 m s-1 too slow with its velocity distribution in these periods. In heavier riming, the vertical Doppler velocities in the WSM6, THOM2, and MORR schemes were ~0.25 m s-1 too slow, while the SBU-YLIN was 0.25 to 0.5 m s-1 too fast. Overall, the BMPs simulate a size distribution close to the observed for D 6 mm in the dendrites, side planes, and mixed habit periods, the BMPs are likely not simulating enough aggregation to create a larger size distribution, although the MORR (double moment) scheme seemed to perform best. These SBNY results will be compared with some results from GCPEx for a warm frontal snow band observed at 18 February 2012.

  2. Climatology of extratropical atmospheric wave packets in the northern hemisphere

    CERN Document Server

    Grazzini, Federico

    2010-01-01

    Planetary and synoptic scale wave-packets represents one important component of the atmospheric large-scale circulation. These dissipative structures are able to rapidly transport eddy kinetic energy, generated locally (e.g. by baroclinic conversion), downstream along the upper tropospheric flow. The transported energy, moving faster than individual weather systems, will affect the development of the next meteorological system on the leading edge of the wave packet, creating a chain of connections between systems that can be far apart in time and space, with important implications on predictability. In this work we present a different and novel approach to investigate atmospheric variability, based on the objective recognition of planetary and synoptic wave packets. We have developed an objective tracking algorithm which allows to extract relevant statistical properties of the wave trains as a function of their dominant wavelength. We have applied the algorithm to the daily analysis (every 12h) from 1958-2009...

  3. Winter Extratropical Cyclogenesis Over The Northern Gulf of Mexico

    Science.gov (United States)

    2011-07-21

    Ahlquist Committee Member Paul H. Ruscher Committee Member ACKNOWLEDGMENTS Many thanks go to my major professor, Dr. Kevin Kloesel, whose...Weather School. I would also like to thank my committee members, Dr. Jon Ahlquist and Dr. Paul Ruscher, for their helpful comments. Dr. Chris Herbster...IN FRICTION LAYER EKMAN PUMPING CUMULUS CONVECTION LATENT HEAT RELEASE MORE RISING MOTION MORE LOW-LEVEL CONVERGENCE Figure 5.2. Schematic diagram of

  4. ANALYSIS OF EXTRATROPICAL TRANSITION OF TROPICAL CYCLONE OVER MAINLAND CHINA

    Institute of Scientific and Technical Information of China (English)

    朱佩君; 郑永光; 陶祖钰

    2003-01-01

    Typhoon Winnie (1997) experienced three stages after landfall on China: weakening, transition, and re-intensification. The transition is similar to the "complex transition" model proposed by Matano and Sekioka. During the re-intensification stage, the transformed cyclone developed into a pattern of Shapiro-Keyser Cyclone model. From the diagnosis we can find that the cause of Winnie's transition is the intrusion of cold air from the mid- and upper- troposphere and the warm temperature advection in the lower. Winnie redeveloped after transition,which is the result of three vital factors: the warm temperature advection in the lower troposphere, the divergence on the right side of the upper jet entry and the cyclonic vorticity advection in the upper.

  5. Reduced models of extratropical low-frequency variability

    Science.gov (United States)

    Strounine, Kirill

    Low-frequency variability (LFV) of the atmosphere refers to its behavior on time scales of 10-100 days, longer than the life cycle of a mid-latitude cyclone but shorter than a season. This behavior is still poorly understood and hard to predict. It has been helpful in gaining understanding that might improve prediction to use various simplified models. The present study compares and contrasts various mode reduction strategies that help derive systematically such simplified models of LFV. Three major strategies have been applied to reduce a fairly realistic, high-dimensional, quasi-geostrophic, 3-level (QG3) atmospheric model to lower dimensions: (i) a purely empirical, multi-level regression procedure, which specifies the functional form of the reduced model and finds the model coefficients by multiple polynomial regression; (ii) an empirical-dynamical method, which retains only a few components in the projection of the full QG3 model equations onto a specified basis (the so-called bare truncation), and finds the linear deterministic and additive stochastic corrections empirically; and (iii) a dynamics-based technique, employing the stochastic mode reduction strategy of Majda et al. (2001; MTV). Subject to the assumption of significant time-scale separation in the physical system under consideration, MTV derives the form of the reduced model and finds its coefficients with minimal statistical fitting. The empirical-dynamical and dynamical reduced models were further improved by sequential parameter estimation and benchmarked against multi-level regression models; the extended Kalman filter (EKF) was used for the parameter estimation. In constructing the reduced models, the choice of basis functions is also important. We considered as basis functions a set of empirical orthogonal functions (EOFs). These EOFs were computed using (a) an energy norm; and (b) a potential-enstrophy norm. We also devised a method, using singular value decomposition of the full-model's linearized propagator, to rotate the EOF basis in a way that emphasizes the low-frequency modes. The reduced model's performance for a given basis was judged by how well that model reproduces statistical properties of the leading LFV modes of the full model, in the same basis. The statistical properties considered included one dimensional probability density functions (PDFs) and autocorrelation functions. We also used Gaussian mixtures to estimate a multi-dimensional PDF in a subspace of leading EOFs to study the regime behavior of the full and reduced models considered. Overall, the reduced models perform better when more statistical information is used in model construction. Thus, the purely empirical stochastic models with quadratic nonlinearity and additive noise reproduce very well the linear properties of the full QG3 model's LFV, i.e. its autocorrelations and spectra, as well as the nonlinear properties, i.e. the persistent flow regimes that induce non-Gaussian features in the model's PDF. The empirical-dynamical models capture the basic statistical properties of the full model's LFV, such as the variance and integral correlation time scales of the leading LFV modes, as well as some of the regime-behavior features, but fail to reproduce the detailed structure of autocorrelations and distort the statistics of the regimes. Dynamical models that use data-assimilation corrections do capture the linear statistics to a degree comparable with that of empirical-dynamical models, but do much less well on the full QG3 model's nonlinear dynamics. There is no appreciable difference between the performance of the models constructed using the energy norm or the potential-vorticity norm in defining the EOFs. The rotated bases were shown to emphasize the system's linear dynamics, which makes them unsuitable for studies of nonlinear behavior of mid-latitude LFV. The analysis of and comparisons between all the reduced models showed that the cubic nonlinear corrections suggested by the MTV stochastic mode reduction approach are not important in modeling the dynamics of the QG3 model and can be neglected when constructing reduced models. Doing so renders the application of mode reduction techniques to realistic atmospheric models with a very large number of variables more feasible. Our results emphasize the need for a robust theory of mid-latitude atmospheric LFV, which does not depend on the restrictive assumption of time-scale separation between low-frequency and synoptic modes. The feasibility of such a theory is illustrated by the apparent success of our purely empirical, proof-of-concept models. While short of providing a comprehensive LFV theory, several ways to improve the mode reduction techniques used in this study are discussed.

  6. Evolving Regional Security in the Andean Region

    Science.gov (United States)

    2004-03-19

    security forces or judicial systems reduces the effectiveness of regional cooperation. Past efforts to achieve consensus among the Andean states have...Trimestre 2001. Nuñez, Joseph. Una Arquitectura para la Seguridad del Siglo XXI par alas Américas: Cooperación Multilateral, Paz y Poder Flexible

  7. Critical Environmental Regions

    Directory of Open Access Journals (Sweden)

    VICTOR SOROCOVSCHI

    2005-01-01

    Full Text Available A short etymological interpretation of the notion of regions (Rette Lineatte, etc.. The region is: R= f (S+P, where S is space and P is power. There follows an evaluation of the characteristics of the region and the presentation of different approaches to the region. From the classic ideas (von Humboldt, 1885, Dokuceaev, 1899, Herbertson, 1905, and others we get to a wide interpretative array of what we accept as organizational spatial units of geographical reality. The environmental region has important connotations with regard to the system as a surrounded element (man, society and the adjacent system. Critical environmental regions are areas where there already exists interactive degradation. The critical character may be physical, hence the “geocritical regions” or the result of human impact, hence the “anthropocritical regions.” Critical situations are differentiated at the local, regional, and global level. In order to understand critical regional situations we must refer to the following characteristics: fragility, resilience, and vulnerability. Still there are few environmental studies on critical regions and work must be done in this field.

  8. Robotics and regional anesthesia.

    Science.gov (United States)

    Wehbe, Mohamad; Giacalone, Marilu; Hemmerling, Thomas M

    2014-10-01

    Robots in regional anesthesia are used as a tool to automate the performance of regional techniques reducing the anesthesiologist's workload and improving patient care. The purpose of this review is to show the latest findings in robotic regional anesthesia. The literature separates robots in anesthesia into two groups: pharmacological robots and manual robots. Pharmacological robots are mainly closed-loop systems that help in the titration of anesthetic drugs to patients undergoing surgery. Manual robots are mechanical robots that are used to support or replace the manual gestures performed by anesthesiologists. Although in the last decade researchers have focused on the development of decision support systems and closed-loop systems, more recent evidence supports the concept that robots can also be useful in performing regional anesthesia techniques. Robots can improve the performance and safety in regional anesthesia. In this review, we present the developments made in robotic and automated regional anesthesia, and discuss the current state of research in this field.

  9. Urban and regional planning

    OpenAIRE

    Pinson, Gilles

    2007-01-01

    Urban and regional planning is a notion that encompasses the whole set of social activities aimed at anticipating, representing and regulating the development of an urban or a regional area. It thus articulates intellectual activities of study and prospective, of social and economic forecasting with more concrete activities such as infrastructure programming, land reservation and land use regulation. Planning operates at different scales: neighborhood, city or region. The concept of governanc...

  10. Entrepreneurship and regional development

    DEFF Research Database (Denmark)

    Müller, Sabine

    This literature review examines how entrepreneurship and regional development has been previously addressed theoretically and empirically. Regional Science and Entrepreneurship are two fields with their own distinct literature's. The question is therefore, how do these two fields talk about...... the respective other? What are the commonalities and differences? The purpose of this article is to create an analytical synthesis by combining the insights of the two literature's in order to gain a fuller understanding of the relation between entrepreneurship and regional development....

  11. Connecting to Regional Markets?

    DEFF Research Database (Denmark)

    Coulibaly, Souleymane; Thomsen, Lotte

    2016-01-01

    Central Asian food processors face a number of constraints when they attempt to export to the region and beyond. The Central Asian economies in focus here are landlocked, and thus lack easy access to sea transport. In addition, the region's transport network was built to reinforce the interdepend......, and makes a novel attempt to examine how these factors lead to challenges for local food processing producers trying to sell their products in the region and beyond....

  12. Regions in Slovenia

    Directory of Open Access Journals (Sweden)

    Andrej Čokert

    1999-12-01

    Full Text Available The reasons behind the need to prepare a law on regions are both internal and external in nature. We need regions as a second level of local government primarily to counter internal development problems and the need for decentralisation in Slovenia. Developmentaly stagnant and depressed areas account for more than 70% of Slovene territory. The share of founds earmarked directly from central government for regional promotion is falling and is lower than the average in European Union countries. Analyses of population and employment, and of the economic, infrastructure and educational capacities of the Slovene regions reveal serious regional differences. The reasons for the establishment of regions in Slovenia also lie in the diversity of regional problems, which are different in Zasavje, Pomurje, Gorenjska or Primorska. Any restriction to an administrative territorial division would blur the special regional features which, even by Europe-wide comparision, are characteristic of Slovenia. And we cannot simplify the tackling of urgent regional problems as being a matter for relations between the central government and a large number of very diverse municipalities.

  13. Border region studies

    DEFF Research Database (Denmark)

    Makkonen, Teemu; Williams, Allan

    2016-01-01

    The contemporary conditions of academic capitalism exert pressures on researchers to avoid ‘peripheral’ journals and ‘unfashionable’ topics. Here an attempt is made to shed light onto the structure of one such ‘offbeat’ field, namely ‘border region studies’, by discussing its geographical...... distribution, key themes, significance and impact. The review suggests that border region studies can be considered a significant and important ‘branch’ of regional studies, which accounts for a small but increasing proportion of regional studies research particularly in Europe and North America. Four main...

  14. Regional Redistribution and Migration

    DEFF Research Database (Denmark)

    Manasse, Paolo; Schultz, Christian

    We study a model with free migration between a rich and a poor region. Since there is congestion, the rich region has an incentive to give the poor region a transfer in order to reduce immigration. Faced with free migration, the rich region voluntarily chooses a transfer, which turns out...... to be equal to that a social planner would choose. Provided migration occurs in equilibrium, this conclusion holds even in the presence of moderate mobility costs. However, large migration costs will lead to suboptimal transfers in the market solution...

  15. Regional Redistribution and Migration

    DEFF Research Database (Denmark)

    Manasse, Paolo; Schultz, Christian

    We study a model with free migration between a rich and a poor region. Since there is congestion, the rich region has an incentive to give the poor region a transfer in order to reduce immigration. Faced with free migration, the rich region voluntarily chooses a transfer, which turns out...... to be equal to that a social planner would choose. Provided migration occurs in equilibrium, this conclusion holds even in the presence of moderate mobility costs. However, large migration costs will lead to suboptimal transfers in the market solution...

  16. European Regional Modernism

    Directory of Open Access Journals (Sweden)

    Vincent Brian Canizaro

    2014-03-01

    Full Text Available In recent years, beginning with the publication in 2003 of Liane Lefaivre and Alexander Tzonis’ 'Critical Regionalism', followed by my 'Architectural Regionalism: Collected Writings on Place, Identity, Modernity and Tradition 'in 2007, there has been a quiet resurgence in the discourse of architectural regionalism.' 'Leuven University Press’s 'Regionalism and Modernity: Architecture in Western Europe 1914–1940 'continues in this direction, with eleven chapters devoted to variations of the regionalist tendency in European architecture focused primarily on Belgium and France, but also Great Britain, Italy, and Germany.

  17. Regional Innovation Clusters

    Data.gov (United States)

    Small Business Administration — The Regional Innovation Clusters serve a diverse group of sectors and geographies. Three of the initial pilot clusters, termed Advanced Defense Technology clusters,...

  18. Impact of geographic variations of the convective and dehydration center on stratospheric water vapor over the Asian monsoon region

    Science.gov (United States)

    Zhang, Kai; Fu, Rong; Wang, Tao; Liu, Yimin

    2016-06-01

    The Asian monsoon region is the most prominent moisture center of water vapor in the lower stratosphere (LS) during boreal summer. Previous studies have suggested that the transport of water vapor to the Asian monsoon LS is controlled by dehydration temperatures and convection mainly over the Bay of Bengal and Southeast Asia. However, there is a clear geographic variation of convection associated with the seasonal and intra-seasonal variations of the Asian monsoon circulation, and the relative influence of such a geographic variation of convection vs. the variation of local dehydration temperatures on water vapor transport is still not clear. Using satellite observations from the Aura Microwave Limb Sounder (MLS) and a domain-filling forward trajectory model, we show that almost half of the seasonal water vapor increase in the Asian monsoon LS are attributable to geographic variations of convection and resultant variations of the dehydration center, of which the influence is comparable to the influence of the local dehydration temperature increase. In particular, dehydration temperatures are coldest over the southeast and warmest over the northwest Asian monsoon region. Although the convective center is located over Southeast Asia, an anomalous increase of convection over the northwest Asia monsoon region increases local diabatic heating in the tropopause layer and air masses entering the LS are dehydrated at relatively warmer temperatures. Due to warmer dehydration temperatures, anomalously moist air enters the LS and moves eastward along the northern flank of the monsoon anticyclonic flow, leading to wet anomalies in the LS over the Asian monsoon region. Likewise, when convection increases over the Southeast Asia monsoon region, dry anomalies appear in the LS. On a seasonal scale, this feature is associated with the monsoon circulation, convection and diabatic heating marching towards the northwest Asia monsoon region from June to August. The march of convection

  19. Regional Size, Wealth and EU Regional Policy

    Directory of Open Access Journals (Sweden)

    José M. Pavía

    2012-01-01

    Full Text Available Los fondos de convergencia tienen como objetivo estimular el crecimiento de las regiones menos desarrolladas dentro de la Unión Europea. Para que una región pueda ser elegida debe ser catalogada como NUTS-2. Sin embargo, como es bien conocido, el valor que toma cualquier variable no es independiente de la escala espacial (y temporal utilizada. El objetivo de este artículo es mostrar la gran sensibilidad que muestra el criterio utilizado en la UE para seleccionar regiones de convergencia y evaluar el impacto que tendría en la distribución del presupuesto entre los diferentes países la utilización de una división territorial diferente.

  20. macro-regional, local y micro- regional

    Directory of Open Access Journals (Sweden)

    José Guadalupe Vargas Hernández

    2006-01-01

    Full Text Available Este trabajo se propone analizar las implicaciones del desarrollo en los niveles macro-regional, local y micro- regional, a partir de la hipótesis central de la teoría del desarrollo que plantea que el desarrollo económico traerá consigo el desarrollo político y social. Después de hacer de un acercamiento conceptual al desarrollo, se repasan brevemente las teorías del desarrollo existentes como herramientas de análisis de la realidad. En la discusión se concluye que los procesos de desarrollo locales y regionales requieren de una transformación sustancial de las relaciones negociadas entre los agentes económicos y los actores políticos. Ante el paulatino retroceso que en las sociedades contemporáneas está teniendo el Estado de bienestar, uno de los principales retos es el empoderamiento de las organizaciones sociales y comunitarias para que desempeñen activamente su rol en los procesos de desarrollo local y regional.

  1. Tourism of Khmelnytskyi region

    Directory of Open Access Journals (Sweden)

    Інна Шоробура

    2017-09-01

    Full Text Available The peculiarities of tourism in Khmelnytskyi region, its priority areas, types, including cultural-educational, environmental, sportrecreative and others have been revealed in the article. The basic tasks of tourism development in the region, aimed at the formation and protection of the tourism-recreational sector, market of competitive services, attraction of maximum number of tourists to the region, etc. have been cleared out. The attention is focused on the main tourist potential of Khmelnytskyi region, including National Nature Park «Podilski Tovtry», National historical-cultural nature reserve «Kamianets», «Samchyky», Medzhybizh regional historical-ethnographic museum-fortress, sanatorium-resort facilities based on mineral waters and others. The attention is paid to the increase in income from tourism. Traditional hospitality of the population of the region, especially in rural areas, provides the possibility to combine tourists’ accommodation with the study of rural customs and traditions directly in the villages. Tourism in Khmelnytskyi region will be attractive to all tourists who want to eat healthy food, to stay outdoors and enjoy the beauty of the region. Also the article tells us about the development of other directions and familiarizes tourists with other enticements of Khmelnytskyi region using the positive brand of Kamianets-Podilskyi. All three potential areas of tourism development (historical tourism in Kamianets-Podilskyi, recreational tourism on rivers, lakes and in the forests, as well as rural tourism can be combined within the global promotion of nature and traditions of the region. It is indicated that Khmelnytskyi is a promising tourist region of Ukraine. The main problems of the region are inadequate tourism infrastructure, accommodation facilities, food and roads. The experience of the tourism cluster «Oberih» (Protective Charm proves the perspectives of agritourism. Developing these two areas together, we

  2. Stratospheric age of air computed with trajectories based on various 3D-Var and 4D-Var data sets

    Directory of Open Access Journals (Sweden)

    M. P. Scheele

    2005-01-01

    Full Text Available The age of stratospheric air is computed with a trajectory model, using ECMWF ERA-40 3D-Var and operational 4D-Var winds. Analysis as well as forecast data are used. In the latter case successive forecast segments are put together to get a time series of the wind fields. This is done for different forecast segment lengths. The sensitivity of the computed age to the forecast segment length and assimilation method are studied, and the results are compared with observations and with results from a chemistry transport model that uses the same data sets. A large number of backward trajectories are started in the stratosphere, and from the fraction of these trajectories that has passed the tropopause the age of air is computed. First, for ten different data sets 50-day backward trajectories starting in the tropical lower stratosphere are computed. The results show that in this region the computed cross-tropopause transport decreases with increasing forecast segment length. Next, for three selected data sets (3D-Var 24-h and 4D-Var 72-h forecast segments, and 4D-Var analyses 5-year backward trajectories are computed that start all over the globe at an altitude of 20km. For all data sets the computed ages of air in the extratropics are smaller than the observation-based age. For 4D-Var forecast series they are closest to the observation-based values, but still 0.5-1.5 year too small. Compared to the difference in age between the results for the different data sets, the difference in age between the trajectory and the chemistry transport model results is small.

  3. Seasonal cycles and variability of O3 and H2O in the UT/LMS during SPURT

    Directory of Open Access Journals (Sweden)

    M. Krebsbach

    2006-01-01

    Full Text Available Airborne high resolution in situ measurements of a large set of trace gases including ozone (O3 and total water (H2O in the upper troposphere and the lowermost stratosphere (UT/LMS have been performed above Europe within the SPURT project. SPURT provides an extensive data coverage of the UT/LMS in each season within the time period between November 2001 and July 2003. In the LMS a distinct spring maximum and autumn minimum is observed in O3, whereas its annual cycle in the UT is shifted by 2–3 months later towards the end of the year. The more variable H2O measurements reveal a maximum during summer and a minimum during autumn/winter with no phase shift between the two atmospheric compartments. For a comprehensive insight into trace gas composition and variability in the UT/LMS several statistical methods are applied using chemical, thermal and dynamical vertical coordinates. In particular, 2-dimensional probability distribution functions serve as a tool to transform localised aircraft data to a more comprehensive view of the probed atmospheric region. It appears that both trace gases, O3 and H2O, reveal the most compact arrangement and are best correlated in the view of potential vorticity (PV and distance to the local tropopause, indicating an advanced mixing state on these surfaces. Thus, strong gradients of PV seem to act as a transport barrier both in the vertical and the horizontal direction. The alignment of trace gas isopleths reflects the existence of a year-round extra-tropical tropopause transition layer. The SPURT measurements reveal that this layer is mainly affected by stratospheric air during winter/spring and by tropospheric air during autumn/summer. Normalised mixing entropy values for O3 and H2O in the LMS appear to be maximal during spring and summer, respectively, indicating highest variability of these trace gases during the respective seasons.

  4. Regional utvikling og partnerskap

    DEFF Research Database (Denmark)

    Halkier, H.; Gjertsen, A.

    2004-01-01

    in European matters as envisaged in the ?Europe of the Regions? slogan. The aim of this chapter is to examine the transformation of regional policy in Denmark from the perspective of political decentralization and Europeanization in order to establish to what extent recent changes have increased the capacity...

  5. Emergence of regional clusters

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Østergaard, Christian Richter; Dalum, Bent

    2010-01-01

    The literature on regional clusters has increased considerably during the last decade. The emergence and growth patterns are usually explained by such factors as unique local culture, regional capabilities, tacit knowledge or the existence of location-specific externalities (knowledge spillovers,...

  6. toward star forming regions

    Directory of Open Access Journals (Sweden)

    Evan Jordan

    2008-01-01

    Full Text Available En este artículo se reportan observaciones de la línea J= 1 → 0 de 12CS en 20 regiones de formación estelar utilizando el telescopio Haystack de 37m del MIT. También se observaron tres regiones en la línea J= 1 → 0 de 13CS, y cinco regiones en la transición de 44 GHz de CH3OH (JK = 70 → 61 A+. Las emisiones de 13CS y CH3OH fueron detectadas en todas las regiones observadas, y la emisión de 12CS fue detectada en 19 de las 20 regiones, 11 de las cuales son nuevas detecciones. Se encontró una alta correlación entre el ancho de la línea de 12CS y la distancia a las regiones, lo que indica que la emisión de 12CS J= 1 → 0 podrá ser utilizada para estimar las distancias a regiones de formación estelar. Asimismo se reporta la detección de variabilidad de los máseres de CH3OH (44 GHz en la mayoría de las regiones observadas.

  7. Forest regions of Montana

    Science.gov (United States)

    Stephen F. Arno

    1979-01-01

    In this paper, Montana is divided into eight geographic subdivisions called "forest regions," based on distributions of tree and undergrowth species and the relationship of these patterns to climate and topography. The regions serve as a geographic reference for describing patterns of forest vegetation across the State. Data on the distributions of plant...

  8. The Wealth of Regions

    DEFF Research Database (Denmark)

    Nistotskaya, Marina; Charron, Nicholas; Lapuente, Victor

    2015-01-01

    . Using original survey data on QoG from 172 regions in eighteen European Union countries, we find that regions where governments are perceived by their citizens as impartial and free from corruption have on average significantly more SMEs. We also find that in less corrupt countries the spatial...

  9. Regionalism, Devolution and Education

    Science.gov (United States)

    Bogdanor, Vernon

    1977-01-01

    Described are effects of political decentralization in the United Kingdom on political and social institutions, particularly education. The author concludes that regionalism could yield advantages of power decentralization, diversity of decision making, and educational systems which are more closely connected to regional and local traditions.…

  10. Politics, Planning and Regionalism.

    Science.gov (United States)

    Zukosky, Jerome

    The concept of regionalism identifies the issues in public affairs pertaining to a region and develops structures through which citizens can participate in the decisionmaking process. This speech describes educational decisions in the State of New York as affected by local decentralization and by concentration of power at the State level. Relevant…

  11. Ad Hoc Rural Regionalism

    Science.gov (United States)

    Hamin, Elisabeth M.; Marcucci, Daniel J.

    2008-01-01

    A new regionalism has been much documented and researched for metropolitan areas; this article documents that there is a new rural regionalism as well. In the United States, these groups appear most likely to emerge in areas that are challenged by outcomes characterizing globalization's effects on the rural condition: namely, exurban or…

  12. The Scandinavian regional model

    DEFF Research Database (Denmark)

    Torfing, Jacob; Lidström, Anders; Røiseland, Asbjørn

    2015-01-01

    This article maps how the sub-national regional levels of governance in Denmark, Norway and Sweden have changed from a high degree of institutional convergence to a pattern of institutional divergence. It analyses the similarities and differences in the changes in regional governance and discusses...

  13. Bridging regional innovation

    DEFF Research Database (Denmark)

    Hansen, Teis

    2013-01-01

    The topics of regional innovation systems (RIS) and cross-border regions attract increasing attention, but few studies combine the themes. Further, the existing empirical studies of cross-border innovation and knowledge creation analyse one case at one point in time, thus, making it difficult...... to assess the progress of integration in the regions, as well as the effect of cross-border innovation policies. Consequently, important questions are left unanswered, including the central research question of this paper: does the sudden removal of significant physical barriers directly impacts...... collaboration activity in cross-border innovation systems? This paper examines regional integration in the Oresund Region over time. It deals with a specific part of the RIS, as it analyses research collaboration between actors from the Danish and Swedish sides, with a specific emphasis on the biotech industry...

  14. Comparisons of cirrus cloud properties between polluted and pristine air based on in-situ observations from the NSF HIPPO, EU INCA and NASA ATTREX campaigns

    Science.gov (United States)

    Diao, M.; Schumann, U.; Jensen, J. B.; Minikin, A.

    2015-12-01

    The radiative forcing of cirrus clouds is influenced by microphysical (e.g., ice crystal number concentration and size distribution) and macroscopic properties. Currently it is still unclear how the formation of cirrus clouds and their microphysical properties are influenced by anthropogenic emissions. In this work, we use airborne in-situ observations to compare cirrus cloud properties between polluted and pristine regions. Our dataset includes: the NSF HIAPER Pole-to-Pole Observations (HIPPO) Global campaign (2009-2011), the EU Interhemispheric Differences In Cirrus Properties from Anthropogenic Emissions (INCA) campaign (2000) and the NASA Airborne Tropical Tropopause Experiment (ATTREX) campaign (2014). The combined dataset include observations of both extratropical (HIPPO and INCA) and tropical (ATTREX) cirrus, over the Northern and Southern Hemispheres. We use the in-situ measured carbon monoxide (CO) mixing ratio as a pollution indicator, and compare ice microphysical properties (i.e., ice crystal number concentration (Nc) and number-weighted mean diameter (Dc)) between air masses with higher and lower CO. All analyses are restricted to T ≤ -40°C. By analyzing ice crystals (Fast-2DC, 87.5-1600 µm) in HIPPO, we found that Dc decreases with increasing CO concentration at multiple constant pressure levels. In addition, analysis of INCA data shows that Nc and extinction of small ice particles (FSSP 3-20 µm) increases with increasing CO. Particles < 87.5 µm in Fast-2DC data are not considered due to uncertainty in sample volume, and the FSSP measurements are subject to possible shattering. We further analyze the ice crystals (SPEC FCDP, 1-50 µm) in the tropical tropopause layer in ATTREX. At -70°C to -90°C, we found that the average Nc (Dc) increases (decreases) at higher CO. Overall, our results suggest that extratropical and tropical cirrus are likely to have more numerous small ice particles, when sampled in the more polluted background. Back

  15. Crisis and Regional Integration

    DEFF Research Database (Denmark)

    Dosenrode, Søren

    ‘Crisis’ has been a word frequently heard of over the last couple of years, both in a global meaning (e.g. the environmental crisis, the financial crisis) and also in a more regional or national meaning, many times related to Africa (Horn of Africa, Ivory Coast, DR Congo, Zimbabwe, Ivory Coast...... at the processes of regional integration in relation to ‘crisis’ in Africa and Europe. First, this paper will look at the concept of ‘crisis’, before it moves on to discuss ‘regional integration’ and the correlation between the two, emphasizing the approaches of neo-functionalism and federal theory...

  16. Constructing Regional advantage

    DEFF Research Database (Denmark)

    Asheim, Bjørn T.; Boschma, Ron; Cooke, Phil

    2011-01-01

    This paper presents a regional innovation policy model based on the idea of constructing regional advantage. This policy model brings together concepts like related variety, knowledge bases and policy platforms. Related variety attaches importance to knowledge spillovers across complementary...... economic development within and between regions in action lines appropriate to incorporate the basic principles behind related variety and differentiated knowledge bases....... sectors. The paper categorizes knowledge into ‘analytical’ (science based), ‘synthetic’ (engineering based) and ‘symbolic’ (arts based) in nature, with different requirements of ‘virtual’ and real proximity mixes. The implications of this are traced for evolving ‘platform policies’ that facilitate...

  17. Connecting to Regional Markets?

    DEFF Research Database (Denmark)

    Coulibaly, Souleymane; Thomsen, Lotte

    2016-01-01

    Central Asian food processors face a number of constraints when they attempt to export to the region and beyond. The Central Asian economies in focus here are landlocked, and thus lack easy access to sea transport. In addition, the region's transport network was built to reinforce...... the interdependence of the then Soviet republics, while conflicting economic interests make cross-border cooperation difficult. Based on extensive fieldwork on infrastructure systems and firm export strategies, this paper identifies contemporary infrastructure and transportation issues within the Central Asian region...

  18. Regional ocean data assimilation.

    Science.gov (United States)

    Edwards, Christopher A; Moore, Andrew M; Hoteit, Ibrahim; Cornuelle, Bruce D

    2015-01-01

    This article reviews the past 15 years of developments in regional ocean data assimilation. A variety of scientific, management, and safety-related objectives motivate marine scientists to characterize many ocean environments, including coastal regions. As in weather prediction, the accurate representation of physical, chemical, and/or biological properties in the ocean is challenging. Models and observations alone provide imperfect representations of the ocean state, but together they can offer improved estimates. Variational and sequential methods are among the most widely used in regional ocean systems, and there have been exciting recent advances in ensemble and four-dimensional variational approaches. These techniques are increasingly being tested and adapted for biogeochemical applications.

  19. Regional Ocean Data Assimilation

    KAUST Repository

    Edwards, Christopher A.

    2015-01-03

    This article reviews the past 15 years of developments in regional ocean data assimilation. A variety of scientific, management, and safety-related objectives motivate marine scientists to characterize many ocean environments, including coastal regions. As in weather prediction, the accurate representation of physical, chemical, and/or biological properties in the ocean is challenging. Models and observations alone provide imperfect representations of the ocean state, but together they can offer improved estimates. Variational and sequential methods are among the most widely used in regional ocean systems, and there have been exciting recent advances in ensemble and four-dimensional variational approaches. These techniques are increasingly being tested and adapted for biogeochemical applications.

  20. Stratospheric ozone intrusion events and their impacts on tropospheric ozone in the Southern Hemisphere

    Directory of Open Access Journals (Sweden)

    J. W. Greenslade

    2017-09-01

    Full Text Available Stratosphere-to-troposphere transport (STT provides an important natural source of ozone to the upper troposphere, but the characteristics of STT events in the Southern Hemisphere extratropics and their contribution to the regional tropospheric ozone budget remain poorly constrained. Here, we develop a quantitative method to identify STT events from ozonesonde profiles. Using this method we estimate the seasonality of STT events and quantify the ozone transported across the tropopause over Davis (69° S, 2006–2013, Macquarie Island (54° S, 2004–2013, and Melbourne (38° S, 2004–2013. STT seasonality is determined by two distinct methods: a Fourier bandpass filter of the vertical ozone profile and an analysis of the Brunt–Väisälä frequency. Using a bandpass filter on 7–9 years of ozone profiles from each site provides clear detection of STT events, with maximum occurrences during summer and minimum during winter for all three sites. The majority of tropospheric ozone enhancements owing to STT events occur within 2.5 and 3 km of the tropopause at Davis and Macquarie Island respectively. Events are more spread out at Melbourne, occurring frequently up to 6 km from the tropopause. The mean fraction of total tropospheric ozone attributed to STT during STT events is  ∼ 1. 0–3. 5 % at each site; however, during individual events, over 10 % of tropospheric ozone may be directly transported from the stratosphere. The cause of STTs is determined to be largely due to synoptic low-pressure frontal systems, determined using coincident ERA-Interim reanalysis meteorological data. Ozone enhancements can also be caused by biomass burning plumes transported from Africa and South America, which are apparent during austral winter and spring and are determined using satellite measurements of CO. To provide regional context for the ozonesonde observations, we use the GEOS-Chem chemical transport model, which is too coarsely

  1. High resolution modeling of the upper troposphere and lower stratosphere region over the Arctic - GEM-AC simulations for the future climate with and without aviation emissions.

    Science.gov (United States)

    Porebska, Magdalena; Struzewska, Joanna; Kaminski, Jacek W.

    2016-04-01

    Upper troposphere and lower stratosphere (UTLS) region is a layer around the tropopause. Perturbation of the chemical composition in the UTLS region can impact physical and dynamical processes that can lead to changes in cloudiness, precipitation, radiative forcing, stratosphere-troposphere exchange and zonal flow. The objective of this study is to investigate the potential impacts of aviation emissions on the upper troposphere and lower stratosphere. In order to assess the impact of the aviation emissions we will focus on changes in atmospheric dynamic due to changes in chemical composition in the UTLS over the Arctic. Specifically, we will assess perturbations in the distribution of the wind, temperature and pressure fields in the UTLS region. Our study will be based on simulations using a high resolution chemical weather model for four scenarios of current (2006) and future (2050) climate: with and without aircraft emissions. The tool that we use is the GEM-AC (Global Environmental Multiscale with Atmospheric Chemistry) chemical weather model where air quality, free tropospheric and stratospheric chemistry processes are on-line and interactive in an operational weather forecast model of Environment Canada. In vertical, the model domain is defined on 70 hybrid levels with model top at 0.1 mb. The gas-phase chemistry includes detailed reactions of Ox, NOx, HOx, CO, CH4, ClOx and BrO. Also, the model can address aerosol microphysics and gas-aerosol partitioning. Aircraft emissions are from the AEDT 2006 database developed by the Federal Aviation Administration (USA) and the future climate simulations are based on RCP8.5 projection presented by the IPCC in the fifth Assessment Report AR5. Results from model simulations on a global variable grid with 0.5o x 0.5o uniform resolution over the Arctic will be presented.

  2. Spearheading Regional Integration

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Shortly after the ASEAN Regional Forum in Kuala Lumpur, Thai Ambassador and rotating Chairman of the ASEAN Beijing Committee, Jullapong Nonsrichai, answered questions from Beijing Review reporter Yan Wei on ASEAN's role and the China-ASEAN relationship.

  3. Regional Air Quality Data

    Data.gov (United States)

    U.S. Environmental Protection Agency — This asset provides data on regional air quality, including trace level SO2, nitric acid, ozone, carbon monoxide, and NOy; and particulate sulfate, nitrate, and...

  4. Regional Snowfall Index (RSI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Climatic Data Center is now producing the Regional Snowfall Index (RSI) for significant snowstorms that impact the eastern two thirds of the U.S. The...

  5. From corridor to region

    DEFF Research Database (Denmark)

    Jensen, Anne; Jespersen, Per Homann

    2006-01-01

    The corridor between Oslo and Berlin is by the politicians of the regional authorities in the Scandinavian part of the corridor seen a region with unique qualities and a large innovation and growth potential. In order to explore and develop this potential an In-terreg project has been launched. E...... this task by applying principles of participative planning and with action research methodology are involving stakeholders in the process of defining, developing and disseminating the idea of the Corridor of Innovation and Cooperation - COINCO.......The corridor between Oslo and Berlin is by the politicians of the regional authorities in the Scandinavian part of the corridor seen a region with unique qualities and a large innovation and growth potential. In order to explore and develop this potential an In-terreg project has been launched...

  6. Region 9 Tribal Lands

    Data.gov (United States)

    U.S. Environmental Protection Agency — Dataset of all Indian Reservations in US EPA Region 9 (California, Arizona and Nevada) with some reservation border areas of adjacent states included (adjacent areas...

  7. Vestnorden. A functional region?

    Directory of Open Access Journals (Sweden)

    Grétar Þór Eyþórsson

    2013-06-01

    Full Text Available This article discusses the issue of what kind of a region Vestnorden is. The need for such a discussion arises from the challenges posed by globalisation for the idea and construction of the West Nordic space, and the need to observe how this regional unit counters these processes. The article is based on an analytical framework which presupposes that a functional region has to consist of four elements. First, whether the space has its own institutions for decision making; second, how far there is economic complementarities among the involved nations and territories; third, to what degree they have common economic interests; and finally, to what extent social, cultural and historical ties exist between the territories involved. The article argues that there is an urgent need to discuss and reorient the institutional functionality of Vestnorden as a regional unit.

  8. Regional National Cooperative Observer

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA publication dedicated to issues, news and recognition of observers in the National Weather Service Cooperative Observer program. Issues published regionally...

  9. Complex Regional Pain Syndrome

    Science.gov (United States)

    Complex regional pain syndrome (CRPS) is a chronic pain condition. It causes intense pain, usually in the arms, hands, legs, or feet. ... in skin temperature, color, or texture Intense burning pain Extreme skin sensitivity Swelling and stiffness in affected ...

  10. Regional Entrepreneurial Scorecard

    Directory of Open Access Journals (Sweden)

    JOSÉ DANIEL LORENZO GÓMEZ

    2008-12-01

    Full Text Available This paper examines the relationship between regional development and the creation of new companies from a micro perspective of institutional approach, focusing on the most relevant stakeholders involved in the process. The contribution of entrepreneurs to regional economic growth has been subject of special attention by the authorities, what is needed for a system of references to assess the adequacy of public programs for the promotion of entrepreneurial activity. Based on the concept of Balanced Scorecard, which provides a logical structure that relates and integrates and allows indicators refl ect the interests of stakeholders in shaping the Balanced Scorecard, the authors propose a Regional Entrepreneurship Scorecard (RES, as a tool for monitoring policies and programmes aimed at promoting start-ups. This RES uses information from international GEM project, which offers a vision of reality enterprising in different countries and regions.

  11. Aeromagnetic Regional Grid Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Several regions are represented in this unique collection of earth surface measurements of magnetic field parameters and their related anomalies. The DNAG Magnetics...

  12. Regional monitoring program

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, B.V.; Soldat, J.K.

    1957-08-26

    The purpose of the Regional Monitoring program is to conduct surveys to detect, measure, and to evaluate environmental radiation, particularly that of HAPO origin. Estimations of total environmental dose and HAPO's contribution to this dose, in units of fraction of public exposure limits, are calculated. Corollary functions include the use of Regional Monitoring data to establish and predict trends in environmental exposure components, and to facilitate correlation of environmental radioactivity with plant processes, process changes, and waste disposal practices.

  13. Regional anesthesia for pediatrics

    OpenAIRE

    Türk, Hacer Şebnem; Işıl, Canan Tülay; Açık, Mehmet Eren; Ediz, Naim; Sayın, Pınar; Tombul, Merih; Oba, Sibel

    2015-01-01

    Objectives: Relevancy to regional anesthesia in pediatrics has increased, because it is complementary to general anesthesia, allows conscious postoperative analgesia without respiratory depression, technical difficulties have been defeated and new local anesthetics have been improved. Therefore we reported data of patients who underwent pediatric surgery and received regional anesthesia.Patients and methods: We retrospectively analyzed data of all patients, who were operated in the pediatric ...

  14. On regional geomagnetic charts

    Science.gov (United States)

    Alldredge, L.R.

    1987-01-01

    When regional geomagnetic charts for areas roughly the size of the US were compiled by hand, some large local anomalies were displayed in the isomagnetic lines. Since the late 1960s, when the compilation of charts using computers and mathematical models was started, most of the details available in the hand drawn regional charts have been lost. One exception to this is the Canadian magnetic declination chart for 1980. This chart was constructed using a 180 degrees spherical harmonic model. -from Author

  15. 3-D evaluation of tropospheric ozone simulations by an ensemble of regional Chemistry Transport Model

    Directory of Open Access Journals (Sweden)

    D. Zyryanov

    2012-04-01

    Full Text Available A detailed 3-D evaluation of an ensemble of five regional Chemistry Transport Models (RCTM and one global CTM with focus on free tropospheric ozone over Europe is presented. It is performed over a summer period (June to August 2008 in the context of the GEMS-RAQ project. A data set of about 400 vertical ozone profiles from balloon soundings and commercial aircraft at 11 different locations is used for model evaluation, in addition to satellite measurements with the infrared nadir sounder (IASI showing largest sensitivity to free tropospheric ozone. In the middle troposphere, the four regional models using the same top and boundary conditions from IFS-MOZART exhibit a systematic negative bias with respect to observed profiles of about −20%. Root Mean Square Error (RMSE values are constantly growing with altitude, from 22% to 32% to 53%, respectively for 0–2 km, 2–8 km and 8–10 km height ranges. Lowest correlation is found in the middle troposphere, with minimum coefficients (R between 0.2 to 0.45 near 8 km, as compared to 0.7 near the surface and similar values around 10 km. A sensitivity test made with the CHIMERE mode also shows that using hourly instead of monthly chemical boundary conditions generally improves the model skill (i.e. improve RMSE and correlation. Lower tropospheric 0–6 km partial ozone columns derived from IASI show a clear North-South gradient over Europe, which is qualitatively reproduced by the models. Also the temporal variability showing decreasing ozone concentrations in the lower troposphere (0–6 km columns during summer is well reproduced by models even if systematic bias remains (the value of the bias being also controlled by the type of used boundary conditions. A multi-day case study of a trough with low tropopause was conducted and showed that both IASI and models were able to resolve strong horizontal gradients of middle and upper tropospheric ozone occurring in the vicinity of an upper

  16. Regional moisture change over India during the past Millennium: A comparison of multi-proxy reconstructions and climate model simulations

    Science.gov (United States)

    Polanski, Stefan; Fallah, Bijan; Befort, Daniel J.; Prasad, Sushma; Cubasch, Ulrich

    2014-11-01

    The Indian Monsoon Variability during the past Millennium has been simulated with the ECHAM5 model in two different time slices: Medieval Climate Anomaly and the Little Ice Age. The simulations are compared with new centennial-resolving paleo-reconstructions inferred from various well-dated multi-proxies from two core regions, the Himalaya and Central India. A qualitative moisture index is derived from the proxies and compared with simulated moisture anomalies. The reconstructed paleo-hydrological changes between the Little Ice Age and the Medieval Climate Anomaly depict a dipole pattern between Himalaya and Central India, which is also captured by the model. In the Medieval Climate Anomaly the model exhibits stronger (weaker) dipole signals during summer (winter) compared to Little Ice Age. In summer (winter) months of "Medieval Climate Anomaly minus Little Ice Age" the model simulates wetter conditions over eastern (western and central) Himalaya. Over Central India, a simulated weakening of Indian Summer Monsoon during warmer climate is coincident with reconstructed drying signal in the Lonar Lake record. Based on the model simulations, we can differentiate three physical mechanisms which can lead to the moisture anomalies: (i) the western and central Himalaya are influenced by extra-tropical Westerlies during winter, (ii) the eastern Himalaya is affected by summer variations of temperature gradient between Bay of Bengal and Indian subcontinent and by a zonal band of intensified Indian-East Asian monsoon link north of 25°N, and (iii) Central India is dominated by summer sea surface temperature anomalies in the northern Arabian Sea which have an effect on the large-scale advection of moist air masses. The temperatures in the Arabian Sea are linked to the Indo Pacific Warm Pool, which modulates the Indian monsoon strength.

  17. Global and regional ocean carbon uptake and climate change: sensitivity to a substantial mitigation scenario

    Energy Technology Data Exchange (ETDEWEB)

    Vichi, Marcello; Masina, Simona; Navarra, Antonio [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy); Manzini, Elisa [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy); Max Planck Institute for Meteorology, Hamburg (Germany); Fogli, Pier Giuseppe [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Alessandri, Andrea [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); ENEA, Rome (Italy); Patara, Lavinia [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Leibniz Institute of Marine Sciences (IFM-GEOMAR), Kiel (Germany); Scoccimarro, Enrico [Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy)

    2011-11-15

    Under future scenarios of business-as-usual emissions, the ocean storage of anthropogenic carbon is anticipated to decrease because of ocean chemistry constraints and positive feedbacks in the carbon-climate dynamics, whereas it is still unknown how the oceanic carbon cycle will respond to more substantial mitigation scenarios. To evaluate the natural system response to prescribed atmospheric ''target'' concentrations and assess the response of the ocean carbon pool to these values, 2 centennial projection simulations have been performed with an Earth System Model that includes a fully coupled carbon cycle, forced in one case with a mitigation scenario and the other with the SRES A1B scenario. End of century ocean uptake with the mitigation scenario is projected to return to the same magnitude of carbon fluxes as simulated in 1960 in the Pacific Ocean and to lower values in the Atlantic. With A1B, the major ocean basins are instead projected to decrease the capacity for carbon uptake globally as found with simpler carbon cycle models, while at the regional level the response is contrasting. The model indicates that the equatorial Pacific may increase the carbon uptake rates in both scenarios, owing to enhancement of the biological carbon pump evidenced by an increase in Net Community Production (NCP) following changes in the subsurface equatorial circulation and enhanced iron availability from extratropical regions. NCP is a proxy of the bulk organic carbon made available to the higher trophic levels and potentially exportable from the surface layers. The model results indicate that, besides the localized increase in the equatorial Pacific, the NCP of lower trophic levels in the northern Pacific and Atlantic oceans is projected to be halved with respect to the current climate under a substantial mitigation scenario at the end of the twenty-first century. It is thus suggested that changes due to cumulative carbon emissions up to present and the

  18. Global and regional ocean carbon uptake and climate change: sensitivity to a substantial mitigation scenario

    Science.gov (United States)

    Vichi, Marcello; Manzini, Elisa; Fogli, Pier Giuseppe; Alessandri, Andrea; Patara, Lavinia; Scoccimarro, Enrico; Masina, Simona; Navarra, Antonio

    2011-11-01

    Under future scenarios of business-as-usual emissions, the ocean storage of anthropogenic carbon is anticipated to decrease because of ocean chemistry constraints and positive feedbacks in the carbon-climate dynamics, whereas it is still unknown how the oceanic carbon cycle will respond to more substantial mitigation scenarios. To evaluate the natural system response to prescribed atmospheric "target" concentrations and assess the response of the ocean carbon pool to these values, 2 centennial projection simulations have been performed with an Earth System Model that includes a fully coupled carbon cycle, forced in one case with a mitigation scenario and the other with the SRES A1B scenario. End of century ocean uptake with the mitigation scenario is projected to return to the same magnitude of carbon fluxes as simulated in 1960 in the Pacific Ocean and to lower values in the Atlantic. With A1B, the major ocean basins are instead projected to decrease the capacity for carbon uptake globally as found with simpler carbon cycle models, while at the regional level the response is contrasting. The model indicates that the equatorial Pacific may increase the carbon uptake rates in both scenarios, owing to enhancement of the biological carbon pump evidenced by an increase in Net Community Production (NCP) following changes in the subsurface equatorial circulation and enhanced iron availability from extratropical regions. NCP is a proxy of the bulk organic carbon made available to the higher trophic levels and potentially exportable from the surface layers. The model results indicate that, besides the localized increase in the equatorial Pacific, the NCP of lower trophic levels in the northern Pacific and Atlantic oceans is projected to be halved with respect to the current climate under a substantial mitigation scenario at the end of the twenty-first century. It is thus suggested that changes due to cumulative carbon emissions up to present and the projected concentration

  19. Heatwaves in Europe: areas of homogeneous variability and links with the regional to large-scale atmospheric and SSTs anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Carril, Andrea F.; Gualdi, Silvio; Cherchi, Annalisa; Navarra, Antonio [Istituto Nazionale di Geofisica e Vulcanologia, INGV, Centro Euro-Mediterraneo per i Cambiamenti Climatici, CMCC, Bologna (Italy)

    2008-01-15

    This work presents a methodology to study the interannual variability associated with summertime months in which extremely hot temperatures are frequent. Daily time series of maximum and minimum temperature fields (T{sub max} and T{sub min}, respectively) are used to define indexes of extreme months based on the number of days crossing thresholds. An empirical orthogonal function (EOF) analysis is applied to the monthly indexes. EOF loadings give information about the geographical areas where the number of days per month with extreme temperatures has the largest variability. Correlations between the EOF principal components and the time series of other fields allow plotting maps highlighting the anomalies in the large scale circulation and in the SSTs that are associated with the occurrence of extreme events. The methodology is used to construct the ''climatology'' of the extremely hot summertime months over Europe. In terms of both interannual and intraseasonal variability, there are three regions in which the frequency of the extremely hot days per month homogeneously varies: north-west Europe, Euro-Mediterranean and Eurasia region. Although extremes over those regions occur during the whole summer (June to August), the anomalous climatic conditions associated with frequent heatwaves present some intraseasonal variability. Extreme climate events over the north-west Europe and Eurasia are typically related to the occurrence of blocking situations. The intraseasonal variability of those patterns is related to the amplitude of the blocking, the relative location of the action centre and the wavetrain of anomalies downstream or upstream of the blocking. During June and July, blocking situations which give extremely hot climate conditions over north-west Europe are also associated with cold conditions over the eastern Mediterranean sector. The Euro-Mediterranean region is a transition area in which extratropical and tropical systems compete

  20. Transient regional osteoporosis

    Directory of Open Access Journals (Sweden)

    F. Trotta

    2011-09-01

    Full Text Available Transient osteoporosis of the hip and regional migratory osteoporosis are uncommon and probably underdiagnosed bone diseases characterized by pain and functional limitation mainly affecting weight-bearing joints of the lower limbs. These conditions are usually self-limiting and symptoms tend to abate within a few months without sequelae. Routine laboratory investigations are unremarkable. Middle aged men and women during the last months of pregnancy or in the immediate post-partum period are principally affected. Osteopenia with preservation of articular space and transitory edema of the bone marrow provided by magnetic resonance imaging are common to these two conditions, so they are also known by the term regional transitory osteoporosis. The appearance of bone marrow edema is not specific to regional transitory osteoporosis but can be observed in several diseases, i.e. trauma, reflex sympathetic dystrophy, avascular osteonecrosis, infections, tumors from which it must be differentiated. The etiology of this condition is unknown. Pathogenesis is still debated in particular the relationship with reflex sympathetic dystrophy, with which regional transitory osteoporosis is often identified. The purpose of the present review is to remark on the relationship between transient osteoporosis of the hip and regional migratory osteoporosis with particular attention to the bone marrow edema pattern and relative differential diagnosis.

  1. North American Regional Report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-11-15

    North America is an energy community fortunate to be endowed with a rich and varied resource base. It consumes about a third of the world's energy and produces about one quarter of world energy supply. North America depends on a mix of complementary energy sources that should remain competitive but not in conflict. The current supply mix varies between Canada, the United States and Mexico, but fossil fuels are dominant across the region, leaving the three member countries vulnerable to a myriad of risks associated with traditional supply sources. Energy trade between all three countries is also a major contributor to the region's economy. Thus, the impetus for collaboration across the region has grown out of the common goals of energy security and economic prosperity. The goal of the WEC regional group was to discuss avenues for advancing North American cooperation and coordination on a range of energy issues. An additional objective was to develop policy recommendations that will facilitate effective development and use of the region's energy resources. Results and recommendtaions are summarized from three forums that focused on the pertinent issues of energy trade, energy efficiency and energy diversification. The inaugural forum (Energy Trade) was held in Washington, D.C. in the fall of 2005. The following summer, the second forum (Energy Efficiency) took place in Mexico City. The third forum (Energy Diversification) was hosted in Halifax, Nova Scotia.

  2. Northeast Regional Biomass Program

    Energy Technology Data Exchange (ETDEWEB)

    Lusk, P.D.

    1992-12-01

    The Northeast Regional Biomass Program has been in operation for a period of nine years. During this time, state managed programs and technical programs have been conducted covering a wide range of activities primarily aim at the use and applications of wood as a fuel. These activities include: assessments of available biomass resources; surveys to determine what industries, businesses, institutions, and utility companies use wood and wood waste for fuel; and workshops, seminars, and demonstrations to provide technical assistance. In the Northeast, an estimated 6.2 million tons of wood are used in the commercial and industrial sector, where 12.5 million cords are used for residential heating annually. Of this useage, 1504.7 mw of power has been generated from biomass. The use of wood energy products has had substantial employment and income benefits in the region. Although wood and woodwaste have received primary emphasis in the regional program, the use of municipal solid waste has received increased emphasis as an energy source. The energy contribution of biomass will increase as potentia users become more familiar with existing feedstocks, technologies, and applications. The Northeast Regional Biomass Program is designed to support region-specific to overcome near-term barriers to biomass energy use.

  3. Regionalization Lessons from Denmark

    DEFF Research Database (Denmark)

    Vrangbæk, Karsten

    2016-01-01

    Denmark is a small Northern European country with an extensive welfare state and a strong commitment to maintaining a universal healthcare system. Like the other countries in the Nordic region, Denmark has a long tradition of democratically governed local and regional governments with extensive...... and coordination. Regions and municipalities in Denmark are governed by directly elected democratic councils. The Danish case is thus an example of democratic decentralization, but within a framework of national coordination and fiscal control. In spite of the difference in size and historical traditions...... there are also many similarities between Canada and Denmark, particularly in terms of health and social policy goals and aspirations, and in terms of the commitment to a comprehensive, universal healthcare system. These similarities provide interesting opportunities for comparison....

  4. Entrepreneurship and Regional Development:

    DEFF Research Database (Denmark)

    Müller, Sabine

    of entrepreneurship). This study sets out to obtain an in-depth understanding of the micro-, community-, and regional-level localized entrepreneurial processes as well as the way in which these processes are intertwined with the spatial context. The contribution of this dissertation lies in the illustration of how...... influenced by such interactions? In approaching these questions, this dissertation focuses on why entrepreneurs act (the causes of entrepreneurship, anchored in the context), how they act (the entrepreneurial practices, action, and activities), and what happens when they act (the outcomes and impact......, culture, history, and natural resources. The insights of this thesis are believed to be vital for understanding why certain types of local entrepreneurship prevail in certain regions. This can further our knowledge of how to foster and enable entrepreneurship in lagging regions. In addition, this study...

  5. From corridor to region

    DEFF Research Database (Denmark)

    Jensen, Anne; Jespersen, Per Homann

    2006-01-01

    The corridor between Oslo and Berlin is by the politicians of the regional authorities in the Scandinavian part of the corridor seen a region with unique qualities and a large innovation and growth potential. In order to explore and develop this potential an In-terreg project has been launched. E...... this task by applying principles of participative planning and with action research methodology are involving stakeholders in the process of defining, developing and disseminating the idea of the Corridor of Innovation and Cooperation - COINCO....

  6. Regional utvikling og partnerskap

    DEFF Research Database (Denmark)

    Halkier, H.; Gjertsen, A.

    2004-01-01

    Since the beginning of the 1990s, Danish regional policy has changed dramatically. As of January 1991, all central government incentive schemes were terminated, and since then the main components of spatial economic policy have been a host of subnational initiatives and the European Structural...... of Danish regions to pursue their own agendas with regard to economic development, and explore the organizational strategies pursued by varies tiers of government in this process of rapid and profound policy change. The text is divided into three parts. The following section provides a brief outline...... to the possible role of the European and other tiers of government in the process....

  7. Cold regions isotope applications

    Energy Technology Data Exchange (ETDEWEB)

    Perrigo, L.D.; Divine, T.E.

    1976-04-01

    Pacific Northwest Laboratories (PNL) started the Cold Regions Isotope Applications Program in FY-1975 to identify special conditions in the Arctic and similar geographic areas (Cold Regions) where radioisotope power, heater, or sterilization systems would be desirable and economically viable. Significant progress was made in the first year of this program and all objectives for this initial 12-month period were achieved. The major conclusions and recommendations resulting for this effort are described below. The areas of interest covered include: radiosterilization of sewage; heating of septic tanks; and radioisotope thermoelectric generators as power sources for meteorological instruments and navigational aids. (TFD)

  8. Constructing Regional advantage

    DEFF Research Database (Denmark)

    Asheim, Bjørn T.; Boschma, Ron; Cooke, Phil

    2011-01-01

    sectors. The paper categorizes knowledge into ‘analytical’ (science based), ‘synthetic’ (engineering based) and ‘symbolic’ (arts based) in nature, with different requirements of ‘virtual’ and real proximity mixes. The implications of this are traced for evolving ‘platform policies’ that facilitate......This paper presents a regional innovation policy model based on the idea of constructing regional advantage. This policy model brings together concepts like related variety, knowledge bases and policy platforms. Related variety attaches importance to knowledge spillovers across complementary...

  9. Regione “Test”

    Directory of Open Access Journals (Sweden)

    Roberto Gasparini

    2012-11-01

    Full Text Available In “Test” region 75% of women (aged 24-64 are screened regularly, meaning every 3 years. A cost-effectiveness analysis shows that, considering regional tariffs, the multiple cohort (12-year-old + 25-year-old women vaccination strategy with a 50% coverage, even if the coverage is much lower than 90%, could prevent 8 cases of cervicocarcinoma and 4 related deaths more than the vaccination of only 12-year-old girls, and thus proves to be cost-effective (8,721 €/QALY.

  10. REGIONAL DEVELOPMENT STRATEGY

    Directory of Open Access Journals (Sweden)

    Vaduva Maria

    2011-01-01

    Full Text Available Regional development policies in the EU Member States have included tools whoseimportance varied from one country to another. Can be identified by negative incentives forregional development policy towards location in crowded areas or control over the location,the reallocation of economic activities in national territory, creation of adequateinfrastructure, measures to enhance development, financial incentives granted toenterprises. Sustainable business development, rehabilitation of social infrastructure,including social housing and improved social services. Improved regional and localtransportation are key areas of intervention rehabilitation and upgrading of county roads,city streets, including road construction and rehabilitation of belt.

  11. Platforms to Regional Economy

    Institute of Scientific and Technical Information of China (English)

    Guo Yan

    2008-01-01

    @@ Besides Canton Fair,China has many other important export and import fairs.Among them,three regional fairs,namely East China Fair(ECF),China Kunming Import & Export Commodities Fair(known as Kunming Fair),and Dalian Import & Export Commodities Fair(DIECF)ale worth the focus.

  12. Promoting regional mobility

    DEFF Research Database (Denmark)

    Jensen, Anne

    Pricing of transport has been part of EU's common transport policy since this gained momentum in the early 1990s. Since then, it has been closely connected to the trans-European transport network (TEN-T) and to rising demands of efficient mobility systems at a local, regional and Community scale....

  13. Modern regional innovation policy

    NARCIS (Netherlands)

    McCann, Philip; Ortega-Argiles, Raquel

    2013-01-01

    This paper analyses the evolution of regional innovation policy into the mainstream of public policy. The paper examines the empirical and theoretical developments which have shifted much of the focus on innovation-related issues to matters of economic geography. As well as academic material we also

  14. Regionalizing global climate models

    NARCIS (Netherlands)

    Pitman, A.J.; Arneth, A.; Ganzeveld, L.N.

    2012-01-01

    Global climate models simulate the Earth's climate impressively at scales of continents and greater. At these scales, large-scale dynamics and physics largely define the climate. At spatial scales relevant to policy makers, and to impacts and adaptation, many other processes may affect regional and

  15. Global, Local, or Regional?

    DEFF Research Database (Denmark)

    Verbeke, Alain; Geisler Asmussen, Christian

    2016-01-01

    of analysis, in addition to the country-level and the global level. Regional strategy analysis requires a fundamental rethink of mainstream theories in the international strategy sphere. This rethink involves, inter alia, internalization theory, with its resource-based view and transaction cost economics...

  16. Eastern Baltic Sea Region

    DEFF Research Database (Denmark)

    Jakobsen, Johnny Grandjean Gøgsig

    2016-01-01

    Kort over den østlige Østersøregion i middelalderen med angivelse af lokaliteter omtalt i antologien, placeret på s.8 i bogen "Church and Belief in the Middle Ages", red. Kirsi Salonen & Sari Katajala-Peltomaa (Amsterdam, 2016)....

  17. Regionalizing global climate models

    NARCIS (Netherlands)

    Pitman, A.J.; Arneth, A.; Ganzeveld, L.N.

    2012-01-01

    Global climate models simulate the Earth's climate impressively at scales of continents and greater. At these scales, large-scale dynamics and physics largely define the climate. At spatial scales relevant to policy makers, and to impacts and adaptation, many other processes may affect regional and

  18. Regionalism and Secession

    Science.gov (United States)

    2015-03-01

    Sobre Cataluña (Madrid: Los Libros de la Catarata, 2014), 112. 269 Ibid. 60 autonomy and not independence.270 Catalan nationalists, aided by the media...de Escritos Sobre Cataluña. Madrid: Los Libros de la Catarata, 2014. Domorenok, Ekaterina,. “The Committee of the Regions: In Search of Identity

  19. Migration and regional inequality

    DEFF Research Database (Denmark)

    Peng, Lianqing; Swider, Sarah

    2017-01-01

    rising, regional inequality has actually decreased, and most recently, remained stable. Our study suggests that China’s unique migratory regime is crucial to understanding these findings. We conduct a counterfactual simulation to demonstrate how migration and remittances have mitigated income inequality...

  20. Australia's Regional Youth Exodus.

    Science.gov (United States)

    Gabriel, M.

    2002-01-01

    Examines media coverage of youth outmigration from Tasmania in the context of Australia's regional crisis. Focuses on how young people are constructed by others and positioned in others' visions of their rural home towns. Discusses two recurring narratives: strategies to keep youth at home, and preoccupation with the "best and brightest"…

  1. Benchmarks: WICHE Region 2012

    Science.gov (United States)

    Western Interstate Commission for Higher Education, 2013

    2013-01-01

    Benchmarks: WICHE Region 2012 presents information on the West's progress in improving access to, success in, and financing of higher education. The information is updated annually to monitor change over time and encourage its use as a tool for informed discussion in policy and education communities. To establish a general context for the…

  2. REGIONAL CUSTOMS DIRECTORATES MANAGEMENT

    Directory of Open Access Journals (Sweden)

    CABA STEFAN

    2009-05-01

    Full Text Available The management of a regional customs directorate is analyzed. A new approach of the managerial system, in the European integration context, is presented. The customs system is one of the first “doors” to a new economic, social and cultural community. For

  3. Regionalism in Scottish Universities

    Science.gov (United States)

    Hutchison, Dougal

    1976-01-01

    It is well-known that Scottish universities are highly local institutions and that over two-fifth of Scottish university students live at home. Attempts to ascertain if this regionalism has relaxed over the past twenty years with student grant regulations, improvement in communications and the increasing affluence of today's society. (Author/RK)

  4. Regionalism. Clip and Save.

    Science.gov (United States)

    Hubbard, Guy

    2002-01-01

    Focuses on the art movement, called Regionalism, discussing the painters involved and describing the characteristics of the art movement. Provides a set of learning activities and background information on John Steuart Curry. Includes a discussion of Curry's painting, "Tornado Over Kansas," and a reproduction of the painting. (CMK)

  5. Approaching Regional Coherence

    DEFF Research Database (Denmark)

    Vestenskov, David; Shah, Ali; Kazmi, Atia

    The report contains ideas on enhanced cooperation on both security and economy. It is a particular relevant read for regional political decision makers, institutions, private companies, and researchers that wish to gain insight into the present and future political and economic developments...

  6. Airborne differential absorption lidar for water vapour measurements in the upper troposphere and lower stratosphere in the spectral region around 940 nm

    Energy Technology Data Exchange (ETDEWEB)

    Poberaj, G.

    2000-07-01

    Two all-solid-state laser systems were developed and studied in detail to optimise their performance for an airborne water vapour differential absorption lidar (DIAL). Their special features are high average output powers and excellent spectral properties in the 940-nm spectral region relevant for monitoring very low water vapour contents in the upper troposphere and lower stratosphere. One system is an injection-seeded pulsed Ti:sapphire ring laser with a spectral bandwidth of 105 MHz and an average power of 1.1 W. The other system is an injection-seeded optical parametric oscillator (OPO) in a ring configuration. Using KTP as nonlinear crystal, a signal output with a spectral bandwidth of 140 MHz and an average power of 1.2 W was achieved. Both systems, the Ti:sapphire ring laser and the KTP OPO, possess spectral purity values higher than 99%. The pump source for these systems is a frequency doubled diode-pumped Nd:YAG laser operating at a repetition rate of 100 Hz. The KTP OPO system has been used as a transmitter in a new airborne water vapour DIAL instrument. For the first time, measurements of two-dimensional water vapour distributions with a high vertical (500 m) and horizontal (20 km) resolution across several potential vorticity streamers were performed. Very low water vapour mixing ratios (10-50 ppmv) and strong gradients were observed in the tropopause region. The sensitivity of the DIAL instrument in the centre of a stratospheric intrusion ranges from 3% in the near field to 12% in the far field (4 km). The first comparison experiments with in situ measuring instruments show a good agreement. Considerable differences are found between DIAL measurements and data obtained from the ECMWF operational analyses and a mesoscale numerical model. (orig.)

  7. Banks, regions and development

    Directory of Open Access Journals (Sweden)

    Pietro Alessandrini

    2003-03-01

    Full Text Available From the 1980s onwards the banking sectors in all the industrialised countries have been experiencing intense restructuring, aggregation and consolidation, radically changing their ownership structures and geography. Whatever the reasons behind such restructuring processes, the globalisation of the credit markets, the consolidation of banking structures, the removal of barriers to the free location of banks and their penetration of peripheral markets pose two main questions. Will integration of the banking systems lead to a narrowing or a widening of the development gap between regions? What relations will there be between financial centres and the periphery, and how will financial labour be divided between national (international banks and local (regional banks? The aim of this paper is to address such questions in the light of recent developments in the theoretical and empirical literature on financial integration.

  8. Regional Stability & Peacebuilding

    DEFF Research Database (Denmark)

    It seems that regional decision makers during the last two decades has been unable to produce a sustainable peacebuilding plan for the region and it is questionable whether any remarkable change will occur in the near future. Some would argue that the political differences are simply too far apart...... continue to face, internal challenges even if agreements with a conflicting state are settled. This only underlines the necessity of initiating sustainable initiatives that are capable of affecting politicians from within, or even to some extent have the capability to bypass the political level....... With contributions from leading international scholars within the field of security studies this book sets out to explain the main security knots preventing stability to emerge and on that basis to test whether a different approach in addressing these knots. By pursuing an innovative and different approach...

  9. Regional Renewable Energy Cooperatives

    Science.gov (United States)

    Hazendonk, P.; Brown, M. B.; Byrne, J. M.; Harrison, T.; Mueller, R.; Peacock, K.; Usher, J.; Yalamova, R.; Kroebel, R.; Larsen, J.; McNaughton, R.

    2014-12-01

    We are building a multidisciplinary research program linking researchers in agriculture, business, earth science, engineering, humanities and social science. Our goal is to match renewable energy supply and reformed energy demands. The program will be focused on (i) understanding and modifying energy demand, (ii) design and implementation of diverse renewable energy networks. Geomatics technology will be used to map existing energy and waste flows on a neighbourhood, municipal, and regional level. Optimal sites and combinations of sites for solar and wind electrical generation (ridges, rooftops, valley walls) will be identified. Geomatics based site and grid analyses will identify best locations for energy production based on efficient production and connectivity to regional grids and transportation. Design of networks for utilization of waste streams of heat, water, animal and human waste for energy production will be investigated. Agriculture, cities and industry produce many waste streams that are not well utilized. Therefore, establishing a renewable energy resource mapping and planning program for electrical generation, waste heat and energy recovery, biomass collection, and biochar, biodiesel and syngas production is critical to regional energy optimization. Electrical storage and demand management are two priorities that will be investigated. Regional scale cooperatives may use electric vehicle batteries and innovations such as pump storage and concentrated solar molten salt heat storage for steam turbine electrical generation. Energy demand management is poorly explored in Canada and elsewhere - our homes and businesses operate on an unrestricted demand. Simple monitoring and energy demand-ranking software can easily reduce peaks demands and move lower ranked uses to non-peak periods, thereby reducing the grid size needed to meet peak demands. Peak demand strains the current energy grid capacity and often requires demand balancing projects and

  10. Regional Strategic Estimate

    Science.gov (United States)

    1992-01-01

    nation’s productivity. b. Guatemala. Several leftist guerrilla groups continue to challenge Guatemala’s fragile democracy ( Organizacion Revolucionario de...light industry and textiles. Mexico’s industrial sector is much greater than that of the rest of the region. The Pan American Highway is a good...boon to the local economy, we may consume scarce resources normally available to domestic industry at its peril. Second, local resources may be rapidly

  11. Regional Seismic Wave Propagation

    Science.gov (United States)

    1979-07-31

    Baikal to the Pamirs, earthquakes occuring in the Baikal region, Sinkiang , the Gobi desert, southwest China and the Himalayas generated Lg/P ratios...data were obtained from stations within the USSR from earthquake events occuring in Baikal, Sinkiang , the Gobi desert, Southwest China and the...earthquakes originating in the Sinkiang province and recorded by seismo- graphic stations along the Pamir-Lena River profile [25] 0 - recorded by short

  12. Northwest Regional Climate Assessment

    Science.gov (United States)

    Lipschultz, Fred

    2011-01-01

    Objectives are to establish a continuing, inclusive National process that: 1) synthesizes relevant science and information 2) increases understanding of what is known & not known 3) identifies information needs related to preparing for climate variability and change, and reducing climate impacts and vulnerability 4) evaluates progress of adaptation & mitigation activities 5) informs science priorities 6) builds assessment capacity in regions and sectors 7) builds understanding & skilled use of findings

  13. Andean region study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-10-01

    New opportunities for climate change mitigation arising from a higher energy integration among Andean Pact nations were analysed within the framework of the UNEP/GEF Project. Apart from the search for regional mitigation actions, the study was mainly aimed at detecting methodological problems which arise when passing from a strictly national view to the co-ordination of regional actions to deal with climate change. In accordance with the available resources and data, and in view of the mainly methodological nature of the project, it was decided to analyse the opportunities to delve into the energy integration of the Region as regards electricity and natural gas industries and their eventual impact on the emission of greenhouse gases. Although possibilities of setting up electricity and natural gas markets are real, their impacts on GHG emission from the energy system would not prove substantially higher than those which the nations could achieve through the use of their own energy resources, in view that the Andean systems are competitive rather than complementary. More in-depth studies and detail information will be required - unavailable for the present study - to be able to properly evaluate all benefits associated with higher energy integration. Nevertheless, the supply of natural gas to Ecuador seems to be the alternative with the highest impact on GHG emission. If we were to analyse the supply and final consumption of energy jointly, we would most certainly detect additional mitigation options resulting from higher co-operation and co-ordination in the energy field. (EHS)

  14. Regional Shelter Analysis Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, Michael B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dennison, Deborah [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kane, Jave [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Walker, Hoyt [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Miller, Paul [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-08-01

    The fallout from a nuclear explosion has the potential to injure or kill 100,000 or more people through exposure to external gamma (fallout) radiation. Existing buildings can reduce radiation exposure by placing material between fallout particles and exposed people. Lawrence Livermore National Laboratory was tasked with developing an operationally feasible methodology that could improve fallout casualty estimates. The methodology, called a Regional Shelter Analysis, combines the fallout protection that existing buildings provide civilian populations with the distribution of people in various locations. The Regional Shelter Analysis method allows the consideration of (a) multiple building types and locations within buildings, (b) country specific estimates, (c) population posture (e.g., unwarned vs. minimally warned), and (d) the time of day (e.g., night vs. day). The protection estimates can be combined with fallout predictions (or measurements) to (a) provide a more accurate assessment of exposure and injury and (b) evaluate the effectiveness of various casualty mitigation strategies. This report describes the Regional Shelter Analysis methodology, highlights key operational aspects (including demonstrating that the methodology is compatible with current tools), illustrates how to implement the methodology, and provides suggestions for future work.

  15. SERVICES AND REGIONAL DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Sven ILLERIS

    2009-12-01

    Full Text Available The purpose of this contribution is to discuss what roles the different economic sectors, and in particular services activities (the tertiary sector play in regional development, understood as growth in production, incomes and employment in weakly developedregions. This question is approached in two ways. The contribution first contains a – primarily theoretical – re-examination of the so-called economic base model, which states that services play a passive role in regional development. The discussion leads to substantial modifications of the model. The second approach is more empirical. It will take as its point of departure the proposition – often heard, but rarely examined – that since service activities are more concentrated in big cities than other activities and in recent decades have shown higher growth rates than other economic activities, it follows that the economic development is now pulled towards big city regions. Examined by way of a statistical analysisin Denmark and France, this proposition could not be verified.

  16. Regionalization Lessons from Denmark.

    Science.gov (United States)

    Vrangbaek, Karsten

    2016-01-01

    Denmark is a small Northern European country with an extensive welfare state and a strong commitment to maintaining a universal healthcare system. Like the other countries in the Nordic region, Denmark has a long tradition of democratically governed local and regional governments with extensive responsibilities in organizing welfare state services. The Danish healthcare system has demonstrated an ability to increase productivity, while at the same time maintaining a high level of patient satisfaction. Ongoing reforms have contributed to these results, as well as a firm commitment to innovation and coordination. Regions and municipalities in Denmark are governed by directly elected democratic councils. The Danish case is thus an example of democratic decentralization, but within a framework of national coordination and fiscal control. In spite of the difference in size and historical traditions there are also many similarities between Canada and Denmark, particularly in terms of health and social policy goals and aspirations, and in terms of the commitment to a comprehensive, universal healthcare system. These similarities provide interesting opportunities for comparison.

  17. Warm Greenland during the last interglacial: the role of regional changes in sea ice cover

    Science.gov (United States)

    Merz, Niklaus; Born, Andreas; Raible, Christoph C.; Stocker, Thomas F.

    2016-10-01

    The last interglacial, also known as the Eemian, is characterized by warmer than present conditions at high latitudes. This is implied by various Eemian proxy records as well as by climate model simulations, though the models mostly underestimate the warming with respect to proxies. Simulations of Eemian surface air temperatures (SAT) in the Northern Hemisphere extratropics further show large variations between different climate models, and it has been hypothesized that this model spread relates to diverse representations of the Eemian sea ice cover. Here we use versions 3 and 4 of the Community Climate System Model (CCSM3 and CCSM4) to highlight the crucial role of sea ice and sea surface temperatures changes for the Eemian climate, in particular in the North Atlantic sector and in Greenland. A substantial reduction in sea ice cover results in an amplified atmospheric warming and thus a better agreement with Eemian proxy records. Sensitivity experiments with idealized lower boundary conditions reveal that warming over Greenland is mostly due to a sea ice retreat in the Nordic Seas. In contrast, sea ice changes in the Labrador Sea have a limited local impact. Changes in sea ice cover in either region are transferred to the overlying atmosphere through anomalous surface energy fluxes. The large-scale spread of the warming resulting from a Nordic Seas sea ice retreat is mostly explained by anomalous heat advection rather than by radiation or condensation processes. In addition, the sea ice perturbations lead to changes in the hydrological cycle. Our results consequently imply that both temperature and snow accumulation records from Greenland ice cores are sensitive to sea ice changes in the Nordic Seas but insensitive to sea ice changes in the Labrador Sea. Moreover, the simulations suggest that the uncertainty in the Eemian sea ice cover accounts for 1.6 °C of the Eemian warming at the NEEM ice core site. The estimated Eemian warming of 5 °C above present day

  18. Distributed Research Center for Analysis of Regional Climatic Changes and Their Impacts on Environment

    Science.gov (United States)

    Shiklomanov, A. I.; Okladnikov, I.; Gordov, E. P.; Proussevitch, A. A.; Titov, A. G.

    2016-12-01

    Presented is a collaborative project carrying out by joint team of researchers from the Institute of Monitoring of Climatic and Ecological Systems, Russia and Earth Systems Research Center, University of New Hampshire, USA. Its main objective is development of a hardware and software prototype of Distributed Research Center (DRC) for monitoring and projecting of regional climatic and and their impacts on the environment over the Northern extratropical areas. In the framework of the project new approaches to "cloud" processing and analysis of large geospatial datasets (big geospatial data) are being developed. It will be deployed on technical platforms of both institutions and applied in research of climate change and its consequences. Datasets available at NCEI and IMCES include multidimensional arrays of climatic, environmental, demographic, and socio-economic characteristics. The project is aimed at solving several major research and engineering tasks: 1) structure analysis of huge heterogeneous climate and environmental geospatial datasets used in the project, their preprocessing and unification; 2) development of a new distributed storage and processing model based on a "shared nothing" paradigm; 3) development of a dedicated database of metadata describing geospatial datasets used in the project; 4) development of a dedicated geoportal and a high-end graphical frontend providing intuitive user interface, internet-accessible online tools for analysis of geospatial data and web services for interoperability with other geoprocessing software packages. DRC will operate as a single access point to distributed archives of spatial data and online tools for their processing. Flexible modular computational engine running verified data processing routines will provide solid results of geospatial data analysis. "Cloud" data analysis and visualization approach will guarantee access to the DRC online tools and data from all over the world. Additionally, exporting of data

  19. Hawaii Regional Sediment Management (RSM): Regional Sediment Budget for the West Maui Region

    Science.gov (United States)

    2016-06-01

    Regional Sediment Management (RSM) Program Hawaii Regional Sediment Management (RSM): Regional Sediment Budget...for the West Maui Region Co as ta l a nd H yd ra ul ic s La bo ra to ry Jessica H. Podoski, Thomas D. Smith, Zeki Demirbilek, Lihwa Lin, and...acwc.sdp.sirsi.net/client/default. Regional Sediment Management (RSM) Program ERDC/CHL TR-16-5 June 2016 Hawaii Regional Sediment

  20. OECD Reviews of Regional Innovation

    DEFF Research Database (Denmark)

    Maguire, Karen; Marsan, Giulia Ajmone; Nauwelaers, Claire;

    This book examines regional innovation in central and southern Denmark, looking at its role in the economy, its governance and policy context and regional strategies for innovation driven growth.......This book examines regional innovation in central and southern Denmark, looking at its role in the economy, its governance and policy context and regional strategies for innovation driven growth....

  1. OECD Reviews of Regional Innovation

    DEFF Research Database (Denmark)

    Maguire, Karen; Marsan, Giulia Ajmone; Nauwelaers, Claire

    This book examines regional innovation in central and southern Denmark, looking at its role in the economy, its governance and policy context and regional strategies for innovation driven growth.......This book examines regional innovation in central and southern Denmark, looking at its role in the economy, its governance and policy context and regional strategies for innovation driven growth....

  2. Contribution of the North Atlantic subtropical high to regional climate model (RCM) skill in simulating southeastern United States summer precipitation

    Science.gov (United States)

    Li, Laifang; Li, Wenhong; Jin, Jiming

    2015-07-01

    This study assesses the skill of advanced regional climate models (RCMs) in simulating southeastern United States (SE US) summer precipitation and explores the physical mechanisms responsible for the simulation skill at a process level. Analysis of the RCM output for the North American Regional Climate Change Assessment Program indicates that the RCM simulations of summer precipitation show the largest biases and a remarkable spread over the SE US compared to other regions in the contiguous US. The causes of such a spread are investigated by performing simulations using the Weather Research and Forecasting (WRF) model, a next-generation RCM developed by the US National Center for Atmospheric Research. The results show that the simulated biases in SE US summer precipitation are due mainly to the misrepresentation of the modeled North Atlantic subtropical high (NASH) western ridge. In the WRF simulations, the NASH western ridge shifts 7° northwestward when compared to that in the reanalysis ensemble, leading to a dry bias in the simulated summer precipitation according to the relationship between the NASH western ridge and summer precipitation over the southeast. Experiments utilizing the four dimensional data assimilation technique further suggest that the improved representation of the circulation patterns (i.e., wind fields) associated with the NASH western ridge substantially reduces the bias in the simulated SE US summer precipitation. Our analysis of circulation dynamics indicates that the NASH western ridge in the WRF simulations is significantly influenced by the simulated planetary boundary layer (PBL) processes over the Gulf of Mexico. Specifically, a decrease (increase) in the simulated PBL height tends to stabilize (destabilize) the lower troposphere over the Gulf of Mexico, and thus inhibits (favors) the onset and/or development of convection. Such changes in tropical convection induce a tropical-extratropical teleconnection pattern, which modulates the

  3. Regiones cognitivas en Colombia

    Directory of Open Access Journals (Sweden)

    Robayo Camilo Alberto

    1996-06-01

    Full Text Available

    Como parte del proyecto en curso: "regiones cognitivas en Colombia", respaldado por Colciencias y el Centro de Investigaciones de la Universidad Pedagógica, este libro constituye el primer informe y sienta las bases para la segunda etapa en la que se están examinando las correlaciones entre estilos cognitivos, comprensión de lenguaje y procesamiento matemático. Redactado en estilo transparente y conciso, este libro asume el reto de explorar y dar consistencia experimental a una regionalización ecocultural de Colombia, enfocándose desde la problemática de la educación. El bajo nivel en logros específicos por área curricular y la concentración de dicha situación por regiones en el país permiten que esta investigación se proyecte desde el inicio como una crítica a los modelos pedagógicos vigentes y una propuesta para su renovación.

  4. Transient regional osteoporosis.

    Science.gov (United States)

    Cano-Marquina, Antonio; Tarín, Juan J; García-Pérez, Miguel-Ángel; Cano, Antonio

    2014-04-01

    Transient regional osteoporosis (TRO) is a disease that predisposes to fragility fracture in weight bearing joints of mid-life women and men. Pregnant women may also suffer the process, usually at the hip. The prevalence of TRO is lower than the systemic form, associated with postmenopause and advanced age, but may be falsely diminished by under-diagnosis. The disease may be uni- or bilateral, and may migrate to distinct joints. One main feature of TRO is spontaneous recovery. Pain and progressive limitation in the functionality of the affected joint(s) are key symptoms. In the case of the form associated with pregnancy, difficulties in diagnosis derive from the relatively young age at presentation and from the clinical overlapping with the frequent aches during gestation. Densitometric osteoporosis in the affected region is not always present, but bone marrow edema, with or without joint effusion, is detected by magnetic resonance. There are not treatment guidelines, but the association of antiresorptives to symptomatic treatment seems to be beneficial. Surgery or other orthopedic interventions can be required for specific indications, like hip fracture, intra-medullary decompression, or other.

  5. Regional migratory osteoporosis

    Energy Technology Data Exchange (ETDEWEB)

    Cahir, John G. [Department of Radiology, Norfolk and Norwich University Hospital, Colney Lane, Norwich, Norfolk NR4 7UY (United Kingdom)], E-mail: john.cahir@nnuh.nhs.uk; Toms, Andoni P. [Department of Radiology, Norfolk and Norwich University Hospital, Colney Lane, Norwich, Norfolk NR4 7UY (United Kingdom)

    2008-07-15

    Regional migratory osteoporosis (RMO) is an uncommon disease characterised by a migrating arthralgia involving the weight bearing joints of the lower limb. The typical imaging findings on radiographs, magnetic resonance imaging, computed tomography and bone scintigraphy are described and illustrated. Men in their fifth and sixth decades of life are most commonly affected. The most common presentation is with proximal to distal spread in the lower limb. The world literature has been reviewed which has revealed 63 documented cases of regional osteoporosis or bone marrow oedema with migratory symptoms. Most of these cases have not been labelled as RMO and therefore the condition is probably under-diagnosed. The radiology of RMO is indistinguishable from transient osteoporosis of the hip (TOH) except for the migratory symptoms and the two conditions are likely to be part of the same spectrum of disease. Systemic osteoporosis is a more recently recognised accompanying feature that hints at an underlying aetiology and an approach to the management of this condition.

  6. Regional Healthcare Effectiveness

    Directory of Open Access Journals (Sweden)

    Olga Vladimirovna Kudelina

    2016-03-01

    Full Text Available An evaluation of healthcare systems effectiveness of the regions of the Russian Federation (federal districts was conducted using the Minmax method based on the data available at the United Interdepartmental Statistical Information System. Four groups of components (i.e. availability of resources; use of resources; access to resources and medical effectiveness decomposed into 17 items were analyzed. The resource availability was measured by four indicators, including the provision of doctors, nurses, hospital beds; agencies providing health care to the population. Use of resources was measured by seven indicators: the average hospital stay, days; the average bed occupancy, days; the number of operations per 1 physician surgical; the cost per unit volume of medical care: in outpatient clinics, day hospitals, inpatient and emergency care. Access to the resources was measured by three indicators: the satisfaction of the population by medical care; the capacity of outpatient clinics; the average number of visits to health facility. The medical effectiveness was also measured by three indicators: incidence with the "first-ever diagnosis of malignancy"; life expectancy at birth, years; the number of days of temporary disability. The study of the dynamics of the components and indexes for 2008–2012 allows to indicate a multidirectional influence on the regional healthcare system. In some federal districts (e.g. North Caucasian, the effectiveness decreases due to resource availability, in others (South, North Caucasian — due to the use of resources, in others (Far Eastern, Ural — due to access to resources. It is found that the effectiveness of the healthcare systems of the federal districts differs significantly. In addition, the built matrix proves the variability the of effectiveness (comparison of expenditures and results of healthcare systems of the federal districts of the Russian Federation: the high results can be obtained at high costs

  7. Strengthening regional safeguards

    Energy Technology Data Exchange (ETDEWEB)

    Palhares, L.; Almeida, G.; Mafra, O. [Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials, Rio de Janeiro (Brazil)] [and others

    1996-08-01

    Nuclear cooperation between Argentina and Brazil has been growing since the early 1980`s and as it grew, so did cooperation with the US Department of Energy (DOE). The Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC) was formed in December 1991 to operate the Common System of Accounting and Control of Nuclear Materials (SCCC). In April 1994, ABACC and the DOE signed an Agreement of Cooperation in nuclear material safeguards. This cooperation has included training safeguards inspectors, exchanging nuclear material measurement and containment and surveillance technology, characterizing reference materials, and studying enrichment plant safeguards. The goal of the collaboration is to exchange technology, evaluate new technology in Latin American nuclear facilities, and strengthen regional safeguards. This paper describes the history of the cooperation, its recent activities, and future projects. The cooperation is strongly supported by all three governments: the Republics of Argentina and Brazil and the United States.

  8. Regional transmission subsystem planning

    Energy Technology Data Exchange (ETDEWEB)

    Costa Bortoni, Edson da [Quadrante Softwares Especializados Ltda., Itajuba, MG (Brazil); Bajay, Sergio Valdir; Barros Correia, Paulo de [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Santos, Afonso Henriques Moreira; Haddad, Jamil [Escola Federal de Engenharia de Itajuba, MG (Brazil)

    1994-12-31

    This work presents an approach for the planning of transmission systems by employing mixed--integer linear programming to obtain a cost and operating characteristics optimized system. The voltage loop equations are written in a modified form, so that, at the end of the analysis, the model behaves as a DC power flow, with the help of the two Kirchhoff`s laws, exempting the need of interaction with an external power flow program for analysis of the line loading. The model considers the occurrence of contingencies, so that the final result is a network robust to the most severe contingencies. This whole technique is adapted to the regional electric power transmission subsystems. (author) 9 refs., 4 figs.

  9. Moldova. Historic regional conference.

    Science.gov (United States)

    Moshin, V

    1995-05-01

    The Directorate of Maternal and Child Health and the Family Planning Association of Moldova organized a regional conference, which was held October 18-19, 1994, in Kishinev, Moldova, with the support of the United Nations Population Fund (UNFPA), the World Health Organization (WHO), and the International Planned Parenthood Federation (IPPF). The conference,"Problems of Family Planning in Eastern Europe," was attended by approximately 400 Moldovan delegates of governmental and nongovernmental organizations (NGOs), and by 25 delegates from Romania, Russia, Belarus, the Ukraine, and Georgia. The President of Moldova and the Ministry of Public Health of Moldova gave their approval. The main objectives of the conference were to inform the public about the recommendations of the ICPD, to analyze the status of women's reproductive health and family planning in Eastern Europe, and to find ways of implementing the ICPD Plan of Action. Major problems identified during the conference were: 1) the social and economic problems facing most families; 2) the high rate of morbidity and mortality; 3) the decrease in birth rate; 4) the increase in abortions; 5) the rising incidence of venereal disease; and 6) the absence of an effective family planning system. It was agreed that cooperation between governments and NGOs is essential in designing population programs for each country. The following goals were set: 1) to provide populations with sufficient contraceptives; 2) to actively promote family planning concepts through the mass media; 3) to train specialists and to open family planning offices and centers; 4) to introduce sex education in the curricula of Pedagogical Institutes; and 5) to create national and regional statistical and sociological databases on population issues.

  10. EPA Regional Boundaries (EPA.EPA_REGIONS) GIS Layer

    Data.gov (United States)

    U.S. Environmental Protection Agency — Each EPA Regional Office is responsible within its states for the execution of the Agency's programs. EPA has ten regional offices, each of which is responsible for...

  11. Challenges Towards Sustainable Tourism for Regional Development of Vlore Region

    OpenAIRE

    Aleks Prifti; Engjellushe Zenelaj

    2013-01-01

    Vlora has great potential for regional development. Tourism can be as a catalyst for theeconomic growth but still have many challenges for sustainable tourism regionaldevelopment. Regional development is one ofthe most important dimensions and key ofEU policy, which is designedto: ensure convergence between the different member statesand regions; ensure regional competitiveness and employment;ensure territorialcooperation. Vlora has all the potential to bean attractive tourismdestination. Res...

  12. Regional brain hypometabolism is unrelated to regional amyloid plaque burden

    Science.gov (United States)

    Altmann, Andre; Ng, Bernard; Landau, Susan M.; Jagust, William J.

    2015-01-01

    See Sorg and Grothe (doi:10.1093/brain/awv302) for a scientific commentary on this article. In its original form, the amyloid cascade hypothesis of Alzheimer’s disease holds that fibrillar deposits of amyloid are an early, driving force in pathological events leading ultimately to neuronal death. Early clinicopathological investigations highlighted a number of inconsistencies leading to an updated hypothesis in which amyloid plaques give way to amyloid oligomers as the driving force in pathogenesis. Rather than focusing on the inconsistencies, amyloid imaging studies have tended to highlight the overlap between regions that show early amyloid plaque signal on positron emission tomography and that also happen to be affected early in Alzheimer’s disease. Recent imaging studies investigating the regional dependency between metabolism and amyloid plaque deposition have arrived at conflicting results, with some showing regional associations and other not. We extracted multimodal neuroimaging data from the Alzheimer’s disease neuroimaging database for 227 healthy controls and 434 subjects with mild cognitive impairment. We analysed regional patterns of amyloid deposition, regional glucose metabolism and regional atrophy using florbetapir (18F) positron emission tomography, 18F-fluordeoxyglucose positron emission tomography and T1-weighted magnetic resonance imaging, respectively. Specifically, we derived grey matter density and standardized uptake value ratios for both positron emission tomography tracers in 404 functionally defined regions of interest. We examined the relation between regional glucose metabolism and amyloid plaques using linear models. For each region of interest, correcting for regional grey matter density, age, education and disease status, we tested the association of regional glucose metabolism with (i) cortex-wide florbetapir uptake; (ii) regional (i.e. in the same region of interest) florbetapir uptake; and (iii) regional florbetapir uptake

  13. Regional Sociological Research Experience

    Directory of Open Access Journals (Sweden)

    Mikhail Vladimirovich Morev

    2015-11-01

    Full Text Available The article presents the experience of the Institute of Socio-Economic Development of Territories of RAS in conducting sociological research on the territory of the Vologda Oblast and the Northwestern Federal District. It describes the historical aspects of formation of the system for public opinion monitoring and examines its theoretical and methodological foundations. The author of the article analyzes the structure of monitoring indicators and provides a brief interpretation of research findings that reflect social wellbeing and social perception trends. In addition, the paper analyzes people’s attitude toward the activities of federal and regional authorities, trends in social well-being, consumer sentiment and also the complex indicator – the index of public sentiment in the region – developed by ISEDT RAS researchers. The results of sociological studies carried out at ISEDT RAS correlate with the dynamics of the all-Russian public opinion polls conducted by the Institute of Sociology of the Russian Academy of Sciences, the Russian Public Opinion Research Center (VCIOM, Levada-Center, etc. They indicate that Russian society gradually adapts to new conditions of life after the collapse of the USSR. Besides, opinion polls show the most important features of the post-Soviet Russian history at its present stage; they are associated with the intensification of international political relations, the consequences of the “Crimean spring” and the new challenges Russia’s economy is facing now. The article concludes that as global community, of which Russian society is part, is evolving, sociological knowledge begins to play an increasingly important role in administration and national security; this is associated with the greater importance attached to intangible development factors. Therefore, a necessary prerequisite for administration effectiveness in all its stages is to implement the results of sociological research on social

  14. American Red Cross Chapter Regions

    Data.gov (United States)

    Department of Homeland Security — The Regions are part of the national field level structure to support chapters. The Regions role is admistrative as well as provides oversight and program technical...

  15. Distances to star forming regions

    CERN Document Server

    Loinard, Laurent

    2014-01-01

    The determination of accurate distances to star-forming regions are discussed in the broader historical context of astronomical distance measurements. We summarize recent results for regions within 1 kpc and present perspectives for the near and more distance future.

  16. Regional Employment Growth, Shocks and Regional Industrial Resilience

    DEFF Research Database (Denmark)

    Holm, J.R.; Østergaard, Christian Richter

    2015-01-01

    The resilience of regional industries to economic shocks has gained a lot of attention in evolutionary economic geography recently. This paper uses a novel quantitative approach to investigate the regional industrial resilience of the Danish information and communication technology (ICT) sector...... to the shock following the burst of the dot.com bubble. It is shown that regions characterized by small and young ICT service companies were more adaptable and grew more than others, while diversity and urbanization increased the sensitivity to the business cycle after the shock. Different types of resilient...... regions are found: adaptively resilient, rigidly resilient, entrepreneurially resilient and non-resilient regions....

  17. Regional employment growth, shocks and regional industrial resilience

    DEFF Research Database (Denmark)

    Holm, Jacob Rubæk; Østergaard, Christian Richter

    2013-01-01

    The resilience of regional industries to economic shocks has gained a lot of attention in evolutionary economic geography recently. This paper uses a novel quantitative approach to investigate the regional industrial resilience of the Danish ICT sector to the shock following the burst of the dot......-com bubble. It is shown that regions characterised by small and young ICT service companies were more adaptable and grew more than others, while diversity and urbanisation increased the sensitivity to the business cycle after the shock. Different types of resilient regions are found: adaptively resilient......, rigidly resilient, entrepreneurially resilient and non-resilient regions....

  18. An Intercomparison of Semi-Eulerian and Lagrangian Based Cyclone Tracking Methods for the North Pacific and Alaskan Regions

    Science.gov (United States)

    Shippee, N. J.; Atkinson, D. E.

    2014-12-01

    The idea of considering the "end user perspective" regarding storm activity and objective tracking methods used to compile information on their behaviour is particularly important in the Alaskan region. Annually, coastal regions in the North are exposed to stormy conditions, though most impacts occur during periods where multiple storms track over the same area in a short period of time (serial cyclones) or where strong storms occur without the presence of a protective sea ice buffer. From a fixed perspective (i.e. Eulerian), a storm may be identified more by the impacts that it generates at that location (winds, sea state, erosion). From a Lagrangian (tracking) view, the intensity, duration, and characteristics of the synoptic environment may prove more relevant for understanding. The overall "effectiveness" of an objective tracking method depends on the intended use of the provided information. While pitting different methods against each other is not necessarily a fruitful exercise (Mesquita et al. 2009), the reality is that one method may better reflect the reality of storm activity and impacts to those experiencing the weather first hand. One of the more subtle points in extra-tropical cyclone tracking and comparison work is the method by which a storm is defined. Most cyclones are analyzed on MSLP fields; others define a cyclone by relative vorticity (ζ) maxima at 850 hPa (NH) and minima (SH). Storms can also be defined by wind events, or even impacts, at a location. Using counts of strong wind events at a grid point or location can account for pressure gradients both associated with storms and absent of a synoptic event. Three separate tracking algorithms are analyzed to determine the method most likely to produce a long-term homogeneous dataset that can be used to train a statistical seasonal prediction method. These methods include the Serreze algorithm, Hodges TRACK algorithm, and Atkinson algorithm. Both the Serreze and Hodges methods provide a tracking

  19. RISK REGION. POINTS OF VIEW

    Directory of Open Access Journals (Sweden)

    VICTOR SOROCOVSCHI

    2016-03-01

    Full Text Available The paper deals with three fundamental issues related to natural risks. The first issue concerns the definition and characteristics of the risk region. The second issue talks about identification of criteria that underly risk regions demarcation and ranking. The analyze of European risk regions exposed to major natural risks and the frequency identification of natural risks affecting major regions of Romania are the topics addressed in the last part of the paper.

  20. regional economic development

    Directory of Open Access Journals (Sweden)

    Robert J. Stimson

    2005-01-01

    Full Text Availab