Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets

Energy Technology Data Exchange (ETDEWEB)

Davis, K J; Richardson, S J; Miles, N L

2007-03-07

Inversions of atmospheric CO2 mixing ratio measurements to determine CO2 sources and sinks are typically limited to coarse spatial and temporal resolution. This limits our ability to evaluate efforts to upscale chamber- and stand-level CO2 flux measurements to regional scales, where coherent climate and ecosystem mechanisms govern the carbon cycle. As a step towards the goal of implementing atmospheric budget or inversion methodology on a regional scale, a network of five relatively inexpensive CO2 mixing ratio measurement systems was deployed on towers in northern Wisconsin. Four systems were distributed on a circle of roughly 150-km radius, surrounding one centrally located system at the WLEF tower near Park Falls, WI. All measurements were taken at a height of 76 m AGL. The systems used single-cell infrared CO2 analyzers (Licor, model LI-820) rather than the siginificantly more costly two-cell models, and were calibrated every two hours using four samples known to within ± 0.2 ppm CO2. Tests prior to deployment in which the systems sampled the same air indicate the precision of the systems to be better than ± 0.3 ppm and the accuracy, based on the difference between the daily mean of one system and a co-located NOAA-ESRL system, is consistently better than ± 0.3 ppm. We demonstrate the utility of the network in two ways. We interpret regional CO2 differences using a Lagrangian parcel approach. The difference in the CO2 mixing ratios across the network is at least 2-3 ppm, which is large compared to the accuracy and precision of the systems. Fluxes estimated assuming Lagrangian parcel transport are of the same sign and magnitude as eddy-covariance flux measurements at the centrally-located WLEF tower. These results indicate that the network will be useful in a full inversion model. Second, we present a case study involving a frontal passage through the region. The progression of a front across the network is evident; changes as large as four ppm in one minute

Atlantic Coast Unique Regional Atmospheric Tracer Experiment (ACURATE)

International Nuclear Information System (INIS)

Schubert, J.F.; Heffter, J.L.; Mead, G.A.

1983-05-01

The Atlantic Coast Unique Regional Atmospheric Tracer Experiment (ACURATE) is a program designed to obtain data necessary to evaluate atmospheric transport and diffusion models used to calculate regional population doses caused by nuclear facility emissions to the atmosphere. This experiment will significantly improve the basis for evaluating the cost effectiveness of different methods of managing airborne nuclear wastes. During the period from March 1982 through September 1982, twice daily air samples have been collected at each of five sampling stations located on a radial from the SRP to Murray Hill, NJ (1000 km). Kr-85 emitted from the F and H area chemical separations facilities is being used as a tracer to determine the transport and diffusion of atmospheric releases from the SRP. The Kr-85 concentrations in the air samples will be compared with the calculated concentrations as predicted by the transport and diffusion models. The Kr-85 data and the meteorological data are being archived and will be made available to the modeling community

Evaluation of a Regional Atmospheric Model Using Measurements of Surface Heat Exchange Processes from a Site in Antarctica

NARCIS (Netherlands)

Lipzig, N.P.M. van; Meijgaard, E. van; Oerlemans, J.

1999-01-01

A regional atmospheric climate model with a horizontal grid spacing of 55 km has been used to simulate the Antarctic atmosphere during an austral summer period. ECMWF reanalyses were used to force the atmospheric prognostic variables from the lateral boundaries. Sea surface temperatures and the sea

Medicanes in an ocean-atmosphere coupled regional climate model

Science.gov (United States)

Akhtar, N.; Brauch, J.; Dobler, A.; Béranger, K.; Ahrens, B.

2014-08-01

So-called medicanes (Mediterranean hurricanes) are meso-scale, marine, and warm-core Mediterranean cyclones that exhibit some similarities to tropical cyclones. The strong cyclonic winds associated with medicanes threaten the highly populated coastal areas around the Mediterranean basin. To reduce the risk of casualties and overall negative impacts, it is important to improve the understanding of medicanes with the use of numerical models. In this study, we employ an atmospheric limited-area model (COSMO-CLM) coupled with a one-dimensional ocean model (1-D NEMO-MED12) to simulate medicanes. The aim of this study is to assess the robustness of the coupled model in simulating these extreme events. For this purpose, 11 historical medicane events are simulated using the atmosphere-only model, COSMO-CLM, and coupled model, with different setups (horizontal atmospheric grid spacings of 0.44, 0.22, and 0.08°; with/without spectral nudging, and an ocean grid spacing of 1/12°). The results show that at high resolution, the coupled model is able to not only simulate most of medicane events but also improve the track length, core temperature, and wind speed of simulated medicanes compared to the atmosphere-only simulations. The results suggest that the coupled model is more proficient for systemic and detailed studies of historical medicane events, and that this model can be an effective tool for future projections.

Modeling concentrations and fluxes of atmospheric CO₂ in the North East Atlantic region

DEFF Research Database (Denmark)

Geels, C.; Christensen, J.H.; Hansen, A.W.

2001-01-01

As part of the Danish NEAREX project a three-dimensional Eulerian hemispheric air pollution model is used to study the transport and concentrations of atmospheric CO2 in the North East Atlantic region. The model domain covers the major part of the Northern Hemisphere and currently the model...

Influence of emissions on regional atmospheric mercury concentrations

Directory of Open Access Journals (Sweden)

Bieser J.

2013-04-01

Full Text Available Mercury is a global pollutant that is rapidly transported in the atmosphere. Unlike the majority of air pollutants the background concentrations of mercury play a major role for the atmospheric concentrations on a hemispheric scale. In this study the influence of regional anthropogenic emissions in comparison to the global emissions on mercury concentrations over Europe are investigated. For this purpose an advanced threedimensional model system is used that consists of three components. The emission model SMOKE-EU, the meteorological model COSMO-CLM, and the chemistry transport model (CTM CMAQ. A variety of sensitivity runs is performed in order to determine the influence of different driving factors (i.e. boundary conditions, anthropogenic and natural emissions, emission factors, meteorological fields on the atmoshperic concentrations of different mercury species. This study is part of the European FP7 project GMOS (Global Mercury Observation System. The aim is to identify the most important drivers for atmospheric mercury in order to optimize future regional modelling studies in the course of the GMOS project. Moreover, the model results are used to determine areas of interest for air-plane based in-situ measurements which are also part of GMOS.

Regional forecasting with global atmospheric models

International Nuclear Information System (INIS)

Crowley, T.J.; North, G.R.; Smith, N.R.

1994-05-01

This report was prepared by the Applied Research Corporation (ARC), College Station, Texas, under subcontract to Pacific Northwest Laboratory (PNL) as part of a global climate studies task. The task supports site characterization work required for the selection of a potential high-level nuclear waste repository and is part of the Performance Assessment Scientific Support (PASS) Program at PNL. The work is under the overall direction of the Office of Civilian Radioactive Waste Management (OCRWM), US Department of Energy Headquarters, Washington, DC. The scope of the report is to present the results of the third year's work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain several studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals

[Regional atmospheric environment risk source identification and assessment].

Science.gov (United States)

Zhang, Xiao-Chun; Chen, Wei-Ping; Ma, Chun; Zhan, Shui-Fen; Jiao, Wen-Tao

2012-12-01

Identification and assessment for atmospheric environment risk source plays an important role in regional atmospheric risk assessment and regional atmospheric pollution prevention and control. The likelihood exposure and consequence assessment method (LEC method) and the Delphi method were employed to build a fast and effective method for identification and assessment of regional atmospheric environment risk sources. This method was applied to the case study of a large coal transportation port in North China. The assessment results showed that the risk characteristics and the harm degree of regional atmospheric environment risk source were in line with the actual situation. Fast and effective identification and assessment of risk source has laid an important foundation for the regional atmospheric environmental risk assessment and regional atmospheric pollution prevention and control.

Improving estimations of greenhouse gas transfer velocities by atmosphere-ocean couplers in Earth-System and regional models

Science.gov (United States)

Vieira, V. M. N. C. S.; Sahlée, E.; Jurus, P.; Clementi, E.; Pettersson, H.; Mateus, M.

2015-09-01

Earth-System and regional models, forecasting climate change and its impacts, simulate atmosphere-ocean gas exchanges using classical yet too simple generalizations relying on wind speed as the sole mediator while neglecting factors as sea-surface agitation, atmospheric stability, current drag with the bottom, rain and surfactants. These were proved fundamental for accurate estimates, particularly in the coastal ocean, where a significant part of the atmosphere-ocean greenhouse gas exchanges occurs. We include several of these factors in a customizable algorithm proposed for the basis of novel couplers of the atmospheric and oceanographic model components. We tested performances with measured and simulated data from the European coastal ocean, having found our algorithm to forecast greenhouse gas exchanges largely different from the forecasted by the generalization currently in use. Our algorithm allows calculus vectorization and parallel processing, improving computational speed roughly 12× in a single cpu core, an essential feature for Earth-System models applications.

Simulation of atmospheric CO2 over Europe and western Siberia using the regional scale model REMO

International Nuclear Information System (INIS)

Chevillard, A.; Ciais, P.; Lafont, S.

2002-01-01

The spatial distribution and the temporal variability of atmospheric CO 2 over Europe and western Siberia are investigated using the regional atmospheric model, REMO. The model, of typical horizontal resolution 50 km, is part of a nested modelling framework that has been established as a concerted action during the EUROSIBERIAN CARBONFLUX project. In REMO, the transport of CO 2 is simulated together with climate variables, which offers the possibility of calculating at each time step the land atmosphere CO 2 fluxes as driven by the modelled meteorology. The uptake of CO 2 by photosynthesis is calculated using a light use efficiency formulation, where the absorbed photosynthetically active solar radiation is inferred from satellite measurements. The release of CO 2 from plant and soil respiration is driven by the simulated climate and assumed to be in equilibrium with photosynthesis over the course of one year. Fossil CO 2 emissions and air-sea fluxes within the model domain are prescribed, whereas the influence of sources outside the model domain is computed from as a boundary condition CO 2 fields determined a global transport model. The modelling results are compared against pointwise eddy covariance fluxes, and against atmospheric CO 2 records. We show that a necessary condition to simulate realistically the variability of atmospheric CO 2 over continental Europe is to account for the diurnal cycle of biospheric exchange. Overall, for the study period of July 1998, REMO realistically simulates the short-term variability of fluxes and of atmospheric mixing ratios. However, the mean CO 2 gradients from western Europe to western Siberia are not correctly reproduced. This latter deficiency points out the key role of boundary conditions in a limited-area model, as well as the need for using more realistic geographic mean patterns of biospheric carbon fluxes

Regionally strong feedbacks between the atmosphere and terrestrial biosphere

Science.gov (United States)

Green, Julia K.; Konings, Alexandra G.; Alemohammad, Seyed Hamed; Berry, Joseph; Entekhabi, Dara; Kolassa, Jana; Lee, Jung-Eun; Gentine, Pierre

2017-06-01

The terrestrial biosphere and atmosphere interact through a series of feedback loops. Variability in terrestrial vegetation growth and phenology can modulate fluxes of water and energy to the atmosphere, and thus affect the climatic conditions that in turn regulate vegetation dynamics. Here we analyse satellite observations of solar-induced fluorescence, precipitation, and radiation using a multivariate statistical technique. We find that biosphere-atmosphere feedbacks are globally widespread and regionally strong: they explain up to 30% of precipitation and surface radiation variance in regions where feedbacks occur. Substantial biosphere-precipitation feedbacks are often found in regions that are transitional between energy and water limitation, such as semi-arid or monsoonal regions. Substantial biosphere-radiation feedbacks are often present in several moderately wet regions and in the Mediterranean, where precipitation and radiation increase vegetation growth. Enhancement of latent and sensible heat transfer from vegetation accompanies this growth, which increases boundary layer height and convection, affecting cloudiness, and consequently incident surface radiation. Enhanced evapotranspiration can increase moist convection, leading to increased precipitation. Earth system models underestimate these precipitation and radiation feedbacks mainly because they underestimate the biosphere response to radiation and water availability. We conclude that biosphere-atmosphere feedbacks cluster in specific climatic regions that help determine the net CO2 balance of the biosphere.

Statistical modeling of temperature, humidity and wind fields in the atmospheric boundary layer over the Siberian region

Science.gov (United States)

Lomakina, N. Ya.

2017-11-01

The work presents the results of the applied climatic division of the Siberian region into districts based on the methodology of objective classification of the atmospheric boundary layer climates by the "temperature-moisture-wind" complex realized with using the method of principal components and the special similarity criteria of average profiles and the eigen values of correlation matrices. On the territory of Siberia, it was identified 14 homogeneous regions for winter season and 10 regions were revealed for summer. The local statistical models were constructed for each region. These include vertical profiles of mean values, mean square deviations, and matrices of interlevel correlation of temperature, specific humidity, zonal and meridional wind velocity. The advantage of the obtained local statistical models over the regional models is shown.

Identification of potential regional sources of atmospheric total gaseous mercury in Windsor, Ontario, Canada using hybrid receptor modeling

Directory of Open Access Journals (Sweden)

X. Xu

2010-08-01

Full Text Available Windsor (Ontario, Canada experiences trans-boundary air pollution as it is located on the border immediately downwind of industrialized regions of the United States of America. A study was conducted in 2007 to identify the potential regional sources of total gaseous mercury (TGM and investigate the effects of regional sources and other factors on seasonal variability of TGM concentrations in Windsor.

TGM concentration was measured at the University of Windsor campus using a Tekran® 2537A Hg vapour analyzer. An annual mean of 2.02±1.63 ng/m³ was observed in 2007. The average TGM concentration was high in the summer (2.48±2.68 ng/m³ and winter (2.17±2.01 ng/m³, compared to spring (1.88±0.78 ng/m³ and fall (1.76±0.58 ng/m³. Hybrid receptor modeling potential source contribution function (PSCF was used by incorporating 72-h backward trajectories and measurements of TGM in Windsor. The results of PSCF were analyzed in conjunction with the Hg emissions inventory of North America (by state/province to identify regions affecting Windsor. In addition to annual modeling, seasonal PSCF modeling was also conducted. The potential source region was identified between 24–61° N and 51–143° W. Annual PSCF modeling identified major sources southwest of Windsor, stretching from Ohio to Texas. The emissions inventory also supported the findings, as Hg emissions were high in those regions. Results of seasonal PSCF modeling were analyzed to find the combined effects of regional sources, meteorological conditions, and surface re-emissions, on seasonal variability of Hg concentrations. It was found that the summer and winter highs of atmospheric Hg can be attributed to areas where large numbers of coal fired power plants are located in the USA. Weak atmospheric dispersion due to low winds and high re-emission from surfaces due to higher temperatures also contributed to high concentrations in

Influence of the orographic roughness of glacier valleys across the Transantarctic Mountains in an atmospheric regional model

Energy Technology Data Exchange (ETDEWEB)

Jourdain, Nicolas C.; Gallee, Hubert [Laboratoire de Glaciologie et Geophysique de l' Environnement, Saint Martin d' Heres (France)

2011-03-15

Glacier valleys across the Transantarctic Mountains are not properly taken into account in climate models, because of their coarse resolution. Nonetheless, glacier valleys control katabatic winds in this region, and the latter are thought to affect the climate of the Ross Sea sector, frsater formation to snow mass balance. The purpose of this paper is to investigate the role of the production of turbulent kinetic energy by the subgrid-scale orography in the Transantarctic Mountains using a 20-km atmospheric regional model. A classical orographic roughness length parametrization is modified to produce either smooth or rough valleys. A one-year simulation shows that katabatic winds in the Transantarctic Mountains are strongly improved using smooth valleys rather than rough valleys. Pressure and temperature fields are affected by the representation of the orographic roughness, specifically in the Transantarctic Mountains and over the Ross Ice Shelf. A smooth representation of escarpment regions shows better agreement with automatic weather station observations than a rough representation. This work stresses the need to improve the representation of subgrid-scale orography to simulate realistic katabatic flows. This paper also provides a way of improving surface winds in an atmospheric model without increasing its resolution. (orig.)

Observations and Modeling of Atmospheric Radiance Structure

National Research Council Canada - National Science Library

Wintersteiner, Peter

2001-01-01

The overall purpose of the work that we have undertaken is to provide new capabilities for observing and modeling structured radiance in the atmosphere, particularly the non-LTE regions of the atmosphere...

Modeling land-surface/atmosphere dynamics for CHAMMP

International Nuclear Information System (INIS)

Gutowski, W.J. Jr.

1993-01-01

Project progress is described on a DOE CHAMP project to model the land-surface/atmosphere coupling in a heterogeneous environment. This work is a collaboration between scientists at Iowa State University and the University of New Hampshire. Work has proceeded in two areas: baseline model coupling and data base development for model validation. The core model elements (land model, atmosphere model) have been ported to the Principal Investigator's computing system and baseline coupling has commenced. The initial target data base is the set of observations from the FIFE field campaign, which is in the process of being acquired. For the remainder of the project period, additional data from the region surrounding the FIFE site and from other field campaigns will be acquired to determine how to best extrapolate results from the initial target region to the rest of the globe. In addition, variants of the coupled model will be used to perform experiments examining resolution requirements and coupling strategies for land-atmosphere coupling in a heterogeneous environment

Understanding Mesoscale Land-Atmosphere Interactions in Arctic Region

Science.gov (United States)

Hong, X.; Wang, S.; Nachamkin, J. E.

2017-12-01

Land-atmosphere interactions in Arctic region are examined using the U.S. Navy Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS©*) with the Noah Land Surface Model (LSM). Initial land surface variables in COAMPS are interpolated from the real-time NASA Land Information System (LIS). The model simulations are configured for three nest grids with 27-9-3 km horizontal resolutions. The simulation period is set for October 2015 with 12-h data assimilation update cycle and 24-h integration length. The results are compared with those simulated without using LSM and evaluated with observations from ONR Sea State R/V Sikuliaq cruise and the North Slope of Alaska (NSA). There are complex soil and vegetation types over the surface for simulation with LSM, compared to without LSM simulation. The results show substantial differences in surface heat fluxes between bulk surface scheme and LSM, which may have an important impact on the sea ice evolution over the Arctic region. Evaluations from station data show surface air temperature and relative humidity have smaller biases for simulation using LSM. Diurnal variation of land surface temperature, which is necessary for physical processes of land-atmosphere, is also better captured than without LSM.

Spatial Variation of Soil Type and Soil Moisture in the Regional Atmospheric Modeling System

Energy Technology Data Exchange (ETDEWEB)

Buckley, R.

2001-06-27

Soil characteristics (texture and moisture) are typically assumed to be initially constant when performing simulations with the Regional Atmospheric Modeling System (RAMS). Soil texture is spatially homogeneous and time-independent, while soil moisture is often spatially homogeneous initially, but time-dependent. This report discusses the conversion of a global data set of Food and Agriculture Organization (FAO) soil types to RAMS soil texture and the subsequent modifications required in RAMS to ingest this information. Spatial variations in initial soil moisture obtained from the National Center for Environmental Predictions (NCEP) large-scale models are also introduced. Comparisons involving simulations over the southeastern United States for two different time periods, one during warmer, more humid summer conditions, and one during cooler, dryer winter conditions, reveals differences in surface conditions related to increases or decreases in near-surface atmospheric moisture con tent as a result of different soil properties. Three separate simulation types were considered. The base case assumed spatially homogeneous soil texture and initial soil moisture. The second case assumed variable soil texture and constant initial soil moisture, while the third case allowed for both variable soil texture and initial soil moisture. The simulation domain was further divided into four geographically distinct regions. It is concluded there is a more dramatic impact on thermodynamic variables (surface temperature and dewpoint) than on surface winds, and a more pronounced variability in results during the summer period. While no obvious trends in surface winds or dewpoint temperature were found relative to observations covering all regions and times, improvement in surface temperatures in most regions and time periods was generally seen with the incorporation of variable soil texture and initial soil moisture.

Verification of atmospheric diffusion models using data of long term atmospheric diffusion experiments

International Nuclear Information System (INIS)

Tamura, Junji; Kido, Hiroko; Hato, Shinji; Homma, Toshimitsu

2009-03-01

Straight-line or segmented plume models as atmospheric diffusion models are commonly used in probabilistic accident consequence assessment (PCA) codes due to cost and time savings. The PCA code, OSCAAR developed by Japan Atomic Energy Research Institute (Present; Japan Atomic Energy Agency) uses the variable puff trajectory model to calculate atmospheric transport and dispersion of released radionuclides. In order to investigate uncertainties involved with the structure of the atmospheric dispersion/deposition model in OSCAAR, we have introduced the more sophisticated computer codes that included regional meteorological models RAMS and atmospheric transport model HYPACT, which were developed by Colorado State University, and comparative analyses between OSCAAR and RAMS/HYPACT have been performed. In this study, model verification of OSCAAR and RAMS/HYPACT was conducted using data of long term atmospheric diffusion experiments, which were carried out in Tokai-mura, Ibaraki-ken. The predictions by models and the results of the atmospheric diffusion experiments indicated relatively good agreements. And it was shown that model performance of OSCAAR was the same degree as it of RAMS/HYPACT. (author)

Influence of the Atmospheric Model on Hanle Diagnostics

Science.gov (United States)

Ishikawa, Ryohko; Uitenbroek, Han; Goto, Motoshi; Iida, Yusuke; Tsuneta, Saku

2018-05-01

We clarify the uncertainty in the inferred magnetic field vector via the Hanle diagnostics of the hydrogen Lyman-α line when the stratification of the underlying atmosphere is unknown. We calculate the anisotropy of the radiation field with plane-parallel semi-empirical models under the nonlocal thermal equilibrium condition and derive linear polarization signals for all possible parameters of magnetic field vectors based on an analytical solution of the atomic polarization and Hanle effect. We find that the semi-empirical models of the inter-network region (FAL-A) and network region (FAL-F) show similar degrees of anisotropy in the radiation field, and this similarity results in an acceptable inversion error ( e.g., {˜} 40 G instead of 50 G in field strength and {˜} 100° instead of 90° in inclination) when FAL-A and FAL-F are swapped. However, the semi-empirical models of FAL-C (averaged quiet-Sun model including both inter-network and network regions) and FAL-P (plage regions) yield an atomic polarization that deviates from all other models, which makes it difficult to precisely determine the magnetic field vector if the correct atmospheric model is not known ( e.g., the inversion error is much larger than 40% of the field strength; {>} 70 G instead of 50 G). These results clearly demonstrate that the choice of model atmosphere is important for Hanle diagnostics. As is well known, one way to constrain the average atmospheric stratification is to measure the center-to-limb variation of the linear polarization signals. The dependence of the center-to-limb variations on the atmospheric model is also presented in this paper.

Sensitivity model study of regional mercury dispersion in the atmosphere

Science.gov (United States)

Gencarelli, Christian N.; Bieser, Johannes; Carbone, Francesco; De Simone, Francesco; Hedgecock, Ian M.; Matthias, Volker; Travnikov, Oleg; Yang, Xin; Pirrone, Nicola

2017-01-01

Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, transport and chemical interactions of atmospheric Hg have been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high-resolution three-dimensional chemical transport models (CTMs), varying the anthropogenic emission datasets, atmospheric Br input fields, Hg oxidation schemes and modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg0(g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution are crucial to the simulated concentration and deposition fields, as is also the choice of Hg0(g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black seas, the English Channel, the Skagerrak Strait and the northern German coast. Considerable influence was found also evident over the Mediterranean, the North Sea and Baltic Sea and some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more HgII(g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O3 / OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg and to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat

Precipitation recycling in West Africa - regional modeling, evaporation tagging and atmospheric water budget analysis

Science.gov (United States)

Arnault, Joel; Kunstmann, Harald; Knoche, Hans-Richard

2015-04-01

Many numerical studies have shown that the West African monsoon is highly sensitive to the state of the land surface. It is however questionable to which extend a local change of land surface properties would affect the local climate, especially with respect to precipitation. This issue is traditionally addressed with the concept of precipitation recycling, defined as the contribution of local surface evaporation to local precipitation. For this study the West African monsoon has been simulated with the Weather Research and Forecasting (WRF) model using explicit convection, for the domain (1°S-21°N, 18°W-14°E) at a spatial resolution of 10 km, for the period January-October 2013, and using ERA-Interim reanalyses as driving data. This WRF configuration has been selected for its ability to simulate monthly precipitation amounts and daily histograms close to TRMM (Tropical Rainfall Measuring Mission) data. In order to investigate precipitation recycling in this WRF simulation, surface evaporation tagging has been implemented in the WRF source code as well as the budget of total and tagged atmospheric water. Surface evaporation tagging consists in duplicating all water species and the respective prognostic equations in the source code. Then, tagged water species are set to zero at the lateral boundaries of the simulated domain (no inflow of tagged water vapor), and tagged surface evaporation is considered only in a specified region. All the source terms of the prognostic equations of total and tagged water species are finally saved in the outputs for the budget analysis. This allows quantifying the respective contribution of total and tagged atmospheric water to atmospheric precipitation processes. The WRF simulation with surface evaporation tagging and budgets has been conducted two times, first with a 100 km2 tagged region (11-12°N, 1-2°W), and second with a 1000 km2 tagged region (7-16°N, 6°W -3°E). In this presentation we will investigate hydro-atmospheric

Global Coupled Model Studies of The Jovian Upper Atmosphere In Response To Electron Precipitation and Ionospheric Convection Within The Auroral Region.

Science.gov (United States)

Millward, G. H.; Miller, S.; Aylward, A. D.

The Jovian Ionospheric Model (JIM) is a global three-dimensional model of Jupiter's coupled ionosphere and thermosphere, developed at University College London. Re- cently, the model has been used to investigate the atmospheric response to electron precipitation within the high-latitude auroral region. A series of simulations have been performed in which the model atmosphere is subjected to monochromatic precipitat- ing electrons of varying number flux and initial energy and, in addition, to various degrees of ionospheric convection. The auroral ionospheric conductivity which re- sults is shown to be strongly non-linear with respect to the incoming electron energy, with a maximum observed for incident particles of initial energy 60 KeV. Electrons with higher energies penetrate the thermospheric region completely, whilst electrons of lower energy (say 10 keV) produce ionisation at higher levels in the atmosphere which are less less condusive to the creation of ionospheric conductivity. Studies of the thermospheric winds with the auroral region show that zonal winds (around the auroral oval) can attain values of around 70% of the driving zonal ion velocity. Also the results show that these large neutral winds are limited in vertical extent to the region of large ionospheric conductivity, tailing off markedly at altitudes above this. The latest results from this work will be presented, and the implications for Jovian magnetospheric-ionospheric coupling will be discussed.

Modelling of the diffusion of pollutants in the atmosphere under varying conditions in large cultivated regions

International Nuclear Information System (INIS)

Wueneke, C.D.; Schultz, H.

1975-01-01

The most important routines of a numerical code based on the particle-in-cell-method for calculating the transport and the turbulent dispersion of inert and radio-active pollutants in the atmosphere have been programmed and have been tested successfully on the CDC computer CYBER 73/76 of the Regional Computer Centre for Niedersachsen in Hanover. Compared to the Gaussian plume model such a numerical code based on the particle-in-cell-method offers several advantages for the computation of the diffusion under varying conditions in large cultivated regions. (orig.) [de

Regional emission and loss budgets of atmospheric methane (2002-2012)

Science.gov (United States)

Saeki, T.; Patra, P. K.; Dlugokencky, E. J.; Ishijima, K.; Umezawa, T.; Ito, A.; Aoki, S.; Morimoto, S.; Kort, E. A.; Crotwell, A. M.; Ravi Kumar, K.; Nakazawa, T.

2015-12-01

Methane (CH4) plays important roles in atmospheric chemistry and short-term forcing of climate. Clear understanding of atmospheric CH4's budget of emissions and losses is required to aid sustainable development of Earth's future environment. We used an atmospheric chemistry-transport model (JAMSTEC's ACTM) for simulating atmospheric CH4. An inverse modeling system has been developed for estimating CH4 emissions (7 ensemble cases) from 53 land regions for 2002-2012 using measurements at 39 sites. Global net CH4 emissions varied between 505-509 and 524-545 Tg/yr during 2002-2004 and 2010-2012, respectively (ranges based on 6 inversion cases), with a step like increase in 2007 in agreement with atmospheric measurement. The inversion system did not account for interannual variations in radicals reacting with CH4 in atmosphere. Our results suggest that the recent update of EDGAR inventory (version 4.2FT2010) overestimated global total emissions by at least 25 Tg/yr in 2010. Increase in CH4 emission since 2004 originated in the tropical and southern hemisphere regions, with timing consistent with an increase of non-dairy cattle stocks by ~10% in 2012 from 1056 million heads in 2002, leading to ~10 Tg/yr increase in emissions from enteric fermentation. All 7 inversions robustly estimated the interannual variations in emissions, but poorly constrained the seasonal cycle amplitude or phase consistently for all regions due to sparse observational network. Forward simulation results using both the a priori and a posteriori emissions are compared with independent aircraft measurements for validation. By doing that we are able to reject the upper limit (545 Tg/yr) of global total emissions as 14 Tg/yr too high during 2008-2012, which allows us to further conclude that CH4 emission increase rate over the East Asia (China mainly) region was 7-8 Tg/yr between the 2002-2006 and 2008-2012 periods, contrary to 1-17 Tg/yr in the a priori emissions.

ESTIMATION AND PROGNOSIS OF QUALITY OF ATMOSPHERIC AIR AT REGIONAL LEVEL

Directory of Open Access Journals (Sweden)

POLISCHUK S. Z.

2016-08-01

Full Text Available Raising of problem. The problem of quality of atmospheric air takes a special place among problems of protection of a surrounding environment. It is caused first of all by vital necessity of atmospheric air for all alive on the Earth, influence of a condition of an atmosphere on global climatic processes and biosphere as a whole due to huge mobility of air weights with which harmful impurity can be transferred. These questions for industrial regions where the level of anthropogenous influence has reached critical size are especially actual. The Dnepropetrovsk area concerns to such regions also. By development of scripts of development of such regions and their territorial components there is a necessity for definition of possible consequences of anthropogenous processes, which occur (or can occur in atmospheric air. It demands strengthening прогнозных functions of ecological monitoring, in particular on atmospheric air, at planning and building of territories, at a choice of the optimum script of town-planning. Purpose. To improve a subsystem of an estimation and the forecast of a condition of atmospheric air on an example of system of ecological monitoring «Pridneprov'e» the Dnepropetrovsk area by means of introduction of a complex of the mathematical models focused on large industrial region which will allow at presence of criteria and parameters to receive as statistical (for the short-term forecast during steady atmospheric processes, and dynamic estimations of a condition of atmospheric air, the forecast of changes of parameters of atmospheric air and distribution of polluting substances, and also their influence on an environment and the person. Conclusion. The offered approach allows to consider complex parameters of steady development, territorial, branch, social, economic and ecological, time aspects, opportunities of atmospheric air as a polyresource, provides the forecast and an estimation of a condition of atmospheric air

Modelling land surface - atmosphere interactions

DEFF Research Database (Denmark)

Rasmussen, Søren Højmark

representation of groundwater in the hydrological model is found to important and this imply resolving the small river valleys. Because, the important shallow groundwater is found in the river valleys. If the model does not represent the shallow groundwater then the area mean surface flux calculation......The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...... by the hydrological model is found to be insensitive to model resolution. Furthermore, this study highlights the effect of bias precipitation by regional climate model and it implications for hydrological modelling....

Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: a multi model linear feedback analysis

International Nuclear Information System (INIS)

Roy, Tilla; Bopp, Laurent; Gehlen, Marion; Cadule, Patricia; Schneider, Birgit; Frolicher, Thomas L.; Segschneider, Joachim; Tjiputra, Jerry; Heinze, Christoph; Joos, Fortunat

2011-01-01

The increase in atmospheric CO 2 over this century depends on the evolution of the oceanic air-sea CO 2 uptake, which will be driven by the combined response to rising atmospheric CO 2 itself and climate change. Here, the future oceanic CO 2 uptake is simulated using an ensemble of coupled climate-carbon cycle models. The models are driven by CO 2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO 2 uptake into a CO 2 -induced component, due to rising atmospheric CO 2 concentrations, and a climate-induced component, due to global warming. The models capture the observation based magnitude and distribution of anthropogenic CO 2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO 2 uptake in the sub polar Southern Ocean and the equatorial regions, owing to decreased CO 2 solubility; and reduced CO 2 uptake in the mid-latitudes, owing to decreased CO 2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extra-tropics, to large freshwater fluxes in the extra-tropical North Atlantic Ocean, and to small changes in the CO 2 solubility in the equatorial regions. In key anthropogenic CO 2 uptake regions, the climate-induced component offsets the CO 2 - induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extra-tropics and 25% in the southern extra-tropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO 2 uptake may be difficult without monitoring additional tracers, such as oxygen. (authors)

Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: a multi model linear feedback analysis

International Nuclear Information System (INIS)

Roy, Tilla; Bopp, Laurent; Gehlen, Marion; Cadule, Patricia

2011-01-01

The increase in atmospheric CO 2 over this century depends on the evolution of the oceanic air-sea CO 2 uptake, which will be driven by the combined response to rising atmospheric CO 2 itself and climate change. Here, the future oceanic CO 2 uptake is simulated using an ensemble of coupled climate-carbon cycle models. The models are driven by CO 2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO 2 uptake into a CO 2 -induced component, due to rising atmospheric CO 2 concentrations, and a climate-induced component, due to global warming. The models capture the observation based magnitude and distribution of anthropogenic CO 2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO 2 uptake in the sub-polar Southern Ocean and the equatorial regions, owing to decreased CO 2 solubility; and reduced CO 2 uptake in the mid latitudes, owing to decreased CO 2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extra tropics, to large freshwater fluxes in the extra tropical North Atlantic Ocean, and to small changes in the CO 2 solubility in the equatorial regions. In key anthropogenic CO 2 uptake regions, the climate-induced component offsets the CO 2 - induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extra tropics and 25% in the southern extra tropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO 2 uptake may be difficult without monitoring additional tracers, such as oxygen. (authors)

Global Atmosphere Watch Workshop on Measurement-Model ...

Science.gov (United States)

The World Meteorological Organization’s (WMO) Global Atmosphere Watch (GAW) Programme coordinates high-quality observations of atmospheric composition from global to local scales with the aim to drive high-quality and high-impact science while co-producing a new generation of products and services. In line with this vision, GAW’s Scientific Advisory Group for Total Atmospheric Deposition (SAG-TAD) has a mandate to produce global maps of wet, dry and total atmospheric deposition for important atmospheric chemicals to enable research into biogeochemical cycles and assessments of ecosystem and human health effects. The most suitable scientific approach for this activity is the emerging technique of measurement-model fusion for total atmospheric deposition. This technique requires global-scale measurements of atmospheric trace gases, particles, precipitation composition and precipitation depth, as well as predictions of the same from global/regional chemical transport models. The fusion of measurement and model results requires data assimilation and mapping techniques. The objective of the GAW Workshop on Measurement-Model Fusion for Global Total Atmospheric Deposition (MMF-GTAD), an initiative of the SAG-TAD, was to review the state-of-the-science and explore the feasibility and methodology of producing, on a routine retrospective basis, global maps of atmospheric gas and aerosol concentrations as well as wet, dry and total deposition via measurement-model

A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry MechanismsChemistry Mechanisms

Science.gov (United States)

We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RAC...

Causes and consequences of mid–21st-century rapid ice loss events simulated by the Rossby centre regional atmosphere-ocean model

Directory of Open Access Journals (Sweden)

Jean-Philippe Paquin

2013-08-01

Full Text Available Recent observations and modelling studies suggest that the Arctic climate is undergoing important transition. One manifestation of this change is seen in the rapid sea-ice cover decrease as experienced in 2007 and 2012. Although most numerical climate models cannot adequately reproduce the recent changes, some models produce similar Rapid Ice Loss Events (RILEs during the mid–21st-century. This study presents an analysis of four specific RILEs clustered around 2040 in three transient climate projections performed with the coupled Rossby Centre regional Atmosphere-Ocean model (RCAO. The analysis shows that long-term thinning causes increased vulnerability of the Arctic Ocean sea-ice cover. In the Atlantic sector, pre-conditioning (thinning of sea ice combined with anomalous atmospheric and oceanic heat transport causes large ice loss, while in the Pacific sector of the Arctic Ocean sea-ice albedo feedback appears important, particularly along the retreating sea-ice margin. Although maximum sea-ice loss occurs in the autumn, response in surface air temperature occurs in early winter, caused by strong increase in ocean-atmosphere surface energy fluxes, mainly the turbulent fluxes. Synchronicity of the events around 2040 in the projections is caused by a strong large-scale atmospheric circulation anomaly at the Atlantic lateral boundary of the regional model. The limited impact on land is caused by vertical propagation of the surface heat anomaly rather than horizontal, caused by the absence of low-level temperature inversion over the ocean.

Developing a high-resolution regional atmospheric reanalysis for Australia

Science.gov (United States)

White, Christopher; Fox-Hughes, Paul; Su, Chun-Hsu; Jakob, Dörte; Kociuba, Greg; Eisenberg, Nathan; Steinle, Peter; Harris, Rebecca; Corney, Stuart; Love, Peter; Remenyi, Tomas; Chladil, Mark; Bally, John; Bindoff, Nathan

2017-04-01

A dynamically consistent, long-term atmospheric reanalysis can be used to support high-quality assessments of environmental risk and likelihood of extreme events. Most reanalyses are presently based on coarse-scale global systems that are not suitable for regional assessments in fire risk, water and natural resources, amongst others. The Australian Bureau of Meteorology is currently working to close this gap by producing a high-resolution reanalysis over the Australian and New Zealand region to construct a sequence of atmospheric conditions at sub-hourly intervals over the past 25 years from 1990. The Australia reanalysis consists of a convective-scale analysis nested within a 12 km regional-scale reanalysis, which is bounded by a coarse-scale ERA-Interim reanalysis that provides the required boundary and initial conditions. We use an unchanging atmospheric modelling suite based on the UERRA system used at the UK Met Office and the more recent version of the Bureau of Meteorology's operational numerical prediction model used in ACCESS-R (Australian Community Climate and Earth-System Simulator-Regional system). An advanced (4-dimensional variational) data assimilation scheme is used to optimally combine model physics with multiple observations from aircrafts, sondes, surface observations and satellites to create a best estimate of state of the atmosphere over a 6-hour moving window. This analysis is in turn used to drive a higher-resolution (1.5 km) downscaling model over selected subdomains within Australia, currently eastern New South Wales and Tasmania, with the capability to support this anywhere in the Australia-New Zealand domain. The temporal resolution of the gridded analysis fields for both the regional and higher-resolution subdomains are generally one hour, with many fields such as 10 m winds and 2 m temperatures available every 10 minutes. The reanalysis also produces many other variables that include wind, temperature, moisture, pressure, cloud cover

Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET)

International Nuclear Information System (INIS)

Ramsdell, J.V. Jr.; Simonen, C.A.; Burk, K.W.

1994-02-01

The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses that individuals may have received from operations at the Hanford Site since 1944. This report deals specifically with the atmospheric transport model, Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET). RATCHET is a major rework of the MESOILT2 model used in the first phase of the HEDR Project; only the bookkeeping framework escaped major changes. Changes to the code include (1) significant changes in the representation of atmospheric processes and (2) incorporation of Monte Carlo methods for representing uncertainty in input data, model parameters, and coefficients. To a large extent, the revisions to the model are based on recommendations of a peer working group that met in March 1991. Technical bases for other portions of the atmospheric transport model are addressed in two other documents. This report has three major sections: a description of the model, a user's guide, and a programmer's guide. These sections discuss RATCHET from three different perspectives. The first provides a technical description of the code with emphasis on details such as the representation of the model domain, the data required by the model, and the equations used to make the model calculations. The technical description is followed by a user's guide to the model with emphasis on running the code. The user's guide contains information about the model input and output. The third section is a programmer's guide to the code. It discusses the hardware and software required to run the code. The programmer's guide also discusses program structure and each of the program elements

RAMS - Regional Atmospheric Modelling System for decision support system SWD-WJ/RODOS

International Nuclear Information System (INIS)

Borysiewicz, M.; Potemski, S.; Galkowski, A.; Zelazinska, B.

1999-01-01

Presented is report aimed at implementation of RAMS (Regional Atmospheric Modelling System) to the decision support system SWD-WJ/RODOS. A comprehensive analysis has been made of different meteorological codes, both local and regional. RAMS code, developed at Colorado State University and Aster Division of Mission Research Corporation, has been selected for reasons presented in this report. RAMS has been adjusted to Polish conditions. Necessary data as topography and surface characteristics (roughness, land percentage, see surface temperature, land cover, soil type, etc.) have been obtained from US Geological Survey and NOAA ARL, Washington DC. Numerical tests have been performed on two nested grids, one covering large part of Europe, the other one covering Polish territory. RAMS requires meteorological input from global model and/or from local meteorological stations. Use has been made of data from the Institute of Meteorology and Water Management, Warsaw, and from European Center for Medium Range Forecast (ECMWF, Reading). For the later RAMS acted operationally what means that global data were delivered every 12 h from Reading via Internet to Swierk and subsequently 12 h weather forecast was calculated by RAMS. In a separate experiment RAMS forecast has been benchmarked with a forecast by UMPL code operated routinely at Warsaw University. Results of all of those test are presented in the report. Finally, some suggestions concerning further work has been put forward. (author)

Estimating the sensitivity of a regional atmospheric model to a sea state dependent roughness using ensemble calculations

Energy Technology Data Exchange (ETDEWEB)

Weisse, R.; Heyen, H.; Storch, H. von [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik

1999-07-01

The sensitivity of an atmospheric high resolution limited area model to a sea state dependent roughness is examined. Two sets of Monte Carlo experiments are compared with each other, one set with a sea state dependent roughness, the other with a roughness parameterized by the standard Charnock relation. From the climatic point of view, i.e., on time scales of months and longer, the differences of mean and standard deviation between the two sets are small and exceed, for instance in winter, where the differences are largest, rarely 0.4 hPa. From the forecasters' point of view, i.e., locally and on a daily time scale, differences of several hPa may occur, but generally differences are smaller than 1 hPa, too. It is concluded that on longer time scales the Charnock relation is a reasonable parameterization in global and regional atmospheric climate models. It is illustrated, too, that the comparison of single realizations, a common practice in regional sensitivity studies, can be misleading. Large differences were found between individual realizations, suggesting a considerable impact of the sea state dependent roughness on the atmosphere. However, it is shown that these differences are to a large fraction caused by internal variability of the atmospheric model itself. (orig.) [German] Die Sensitivitaet eines atmosphaerischen Regionalmodells bezueglich einer seegangsabhaengigen Rauhigkeit wird mittels Ensemblerechnungen untersucht. Dazu werden eine Reihe von Monte-Carlo-Experimenten mit und ohne seegangsabhaengige Rauhigkeit verglichen. Im letzten Fall wird die Charnock-Relation zur Bestimmung der Rauhigkeit verwendet. Auf Zeitskalen von Monaten und laenger sind die Unterschiede zwischen den Experimenten mit und denen ohne seegangsabhaengige Rauhigkeit gering. Auf der lokalen und der taeglichen Skala koennen jedoch Unterschiede von einigen hPa im Bodenluftdruckfeld auftreten. Es wird gezeigt, dass diese Unterschiede jedoch weniger eine Reaktion des

Do regions outside the tropical Pacific influence ENSO through atmospheric teleconnections?

Digital Repository Service at National Institute of Oceanography (India)

Dayan, H.; Izumo, T.; Vialard, J.; Lengaigne, M.; Masson, S

This paper aims at identifying oceanic regions outside the tropical Pacific, which may influence the El Ni�o Southern Oscillation (ENSO) through interannual modulation of equatorial Pacific winds An Atmospheric General Circulation Model (AGCM) 7...

Regional Ocean Modeling System (ROMS): CNMI

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 7-day, 3-hourly forecast for the region surrounding the Commonwealth of the Northern Mariana Islands (CNMI) at approximately...

Simulation of atmospheric dispersion of radionuclides using an Eulerian-Lagrangian modelling system.

Science.gov (United States)

Basit, Abdul; Espinosa, Francisco; Avila, Ruben; Raza, S; Irfan, N

2008-12-01

In this paper we present an atmospheric dispersion scenario for a proposed nuclear power plant in Pakistan involving the hypothetical accidental release of radionuclides. For this, a concept involving a Lagrangian stochastic particle model (LSPM) coupled with an Eulerian regional atmospheric modelling system (RAMS) is used. The atmospheric turbulent dispersion of radionuclides (represented by non-buoyant particles/neutral traces) in the LSPM is modelled by applying non-homogeneous turbulence conditions. The mean wind velocities governed by the topography of the region and the surface fluxes of momentum and heat are calculated by the RAMS code. A moving least squares (MLS) technique is introduced to calculate the concentration of radionuclides at ground level. The numerically calculated vertical profiles of wind velocity and temperature are compared with observed data. The results obtained demonstrate that in regions of complex terrain it is not sufficient to model the atmospheric dispersion of particles using a straight-line Gaussian plume model, and that by utilising a Lagrangian stochastic particle model and regional atmospheric modelling system a much more realistic estimation of the dispersion in such a hypothetical scenario was ascertained. The particle dispersion results for a 12 h ground release show that a triangular area of about 400 km(2) situated in the north-west quadrant of release is under radiological threat. The particle distribution shows that the use of a Gaussian plume model (GPM) in such situations will yield quite misleading results.

Regional Ocean Modeling System (ROMS): Samoa

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 7-day, 3-hourly forecast for the region surrounding the islands of Samoa at approximately 3-km resolution. While considerable...

Regional Ocean Modeling System (ROMS): Guam

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 6-day, 3-hourly forecast for the region surrounding Guam at approximately 2-km resolution. While considerable effort has been...

Regional Ocean Modeling System (ROMS): Oahu

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 7-day, 3-hourly forecast for the region surrounding the island of Oahu at approximately 1-km resolution. While considerable...

Comparing atmospheric transport models for future regional inversions over Europe - Part 1: mapping the atmospheric CO2 signals

International Nuclear Information System (INIS)

Geels, C.; Brandt, J.; Christensen, J.H.; Frohn, L.M.; Gloor, M.; Ciais, P.; Bousquet, P.; Peylin, P.; Dargaville, R.; Ramonet, M.; Vermeulen, A.T.; Aalto, T.; Haszpra, L.; Karstens, U.; Rodenbeck, C.; Carboni, G.; Santaguida, R.

2007-01-01

The CO 2 source and sink distribution across Europe can be estimated in principle through inverse methods by combining CO 2 observations and atmospheric transport models. Uncertainties of such estimates are mainly due to insufficient spatio-temporal coverage of CO 2 observations and biases of the models. In order to assess the biases related to the use of different models the CO 2 concentration field over Europe has been simulated with five different Eulerian atmospheric transport models as part of the EU-funded AEROCARB project, which has the main goal to estimate the carbon balance of Europe. In contrast to previous comparisons, here both global coarse-resolution and regional higher-resolution models are included. Continuous CO 2 observations from continental, coastal and mountain sites as well as flasks sampled on aircraft are used to evaluate the models ability to capture the spatio-temporal variability and distribution of lower troposphere CO 2 across Europe. 14 CO 2 is used in addition to evaluate separately fossil fuel signal predictions. The simulated concentrations show a large range of variation, with up to similar to 10 ppm higher surface concentrations over Western and Central Europe in the regional models with highest (mesoscale) spatial resolution. The simulation-data comparison reveals that generally high-resolution models are more successful than coarse models in capturing the amplitude and phasing of the observed short-term variability. At high-altitude stations the magnitude of the differences between observations and models and in between models is less pronounced, but the timing of the diurnal cycle is not well captured by the models. The data comparisons show also that the timing of the observed variability on hourly to daily time scales at low-altitude stations is generally well captured by all models. However, the amplitude of the variability tends to be underestimated. While daytime values are quite well predicted, nighttime values are

Automated Detection of Oscillating Regions in the Solar Atmosphere

Science.gov (United States)

Ireland, J.; Marsh, M. S.; Kucera, T. A.; Young, C. A.

2010-01-01

Recently observed oscillations in the solar atmosphere have been interpreted and modeled as magnetohydrodynamic wave modes. This has allowed for the estimation of parameters that are otherwise hard to derive, such as the coronal magnetic-field strength. This work crucially relies on the initial detection of the oscillations, which is commonly done manually. The volume of Solar Dynamics Observatory (SDO) data will make manual detection inefficient for detecting all of the oscillating regions. An algorithm is presented that automates the detection of areas of the solar atmosphere that support spatially extended oscillations. The algorithm identifies areas in the solar atmosphere whose oscillation content is described by a single, dominant oscillation within a user-defined frequency range. The method is based on Bayesian spectral analysis of time series and image filtering. A Bayesian approach sidesteps the need for an a-priori noise estimate to calculate rejection criteria for the observed signal, and it also provides estimates of oscillation frequency, amplitude, and noise, and the error in all of these quantities, in a self-consistent way. The algorithm also introduces the notion of quality measures to those regions for which a positive detection is claimed, allowing for simple post-detection discrimination by the user. The algorithm is demonstrated on two Transition Region and Coronal Explorer (TRACE) datasets, and comments regarding its suitability for oscillation detection in SDO are made.

Impact of absorbing aerosols on the simulation of climate over the Indian region in an atmospheric general circulation model

Directory of Open Access Journals (Sweden)

A. Chakraborty

2004-04-01

Full Text Available The impact of anthropogenic absorbing aerosols (such as soot on the climate over the Indian region has been studied using the NCMRWF general circulation model. The absorbing aerosols increase shortwave radiative heating of the lower troposphere and reduce the heating at the surface. These effects have been incorporated as heating of the lower troposphere (up to 700hPa and cooling over the continental surface based on INDOEX measurements. The heating effect is constant in the pre-monsoon season and reduces to zero during the monsoon season. It is shown that even in the monsoon season when the aerosol forcing is zero, there is an overall increase in rainfall and a reduction in surface temperature over the Indian region. The rainfall averaged over the Tropics shows a small reduction in most of the months during the January to September period. The impact of aerosol forcing, the model's sensitivity to this forcing and its interaction with model-physics has been studied by changing the cumulus parameterization from the Simplified Arakawa-Schubert (SAS scheme to the Kuo scheme. During the pre-monsoon season the major changes in precipitation occur in the oceanic Inter Tropical Convergence Zone (ITCZ, where both the schemes show an increase in precipitation. This result is similar to that reported in Chung2002. On the other hand, during the monsoon season the changes in precipitation in the continental region are different in the SAS and Kuo schemes. It is shown that the heating due to absorbing aerosols changes the vertical moist-static stability of the atmosphere. The difference in the precipitation changes in the two cumulus schemes is on account of the different responses in the two parameterization schemes to changes in vertical stability. Key words. Atmospheric composition and structure (aerosols and particles – Meteorology and atmospheric dynamics (tropical meteorology; precipitation

Sensitivity of modeled atmospheric nitrogen species and nitrogen deposition to variations in sea salt emissions in the North Sea and Baltic Sea regions

Directory of Open Access Journals (Sweden)

D. Neumann

2016-03-01

Full Text Available Coarse sea salt particles are emitted ubiquitously from the ocean surface by wave-breaking and bubble-bursting processes. These particles impact the atmospheric chemistry by affecting the condensation of gas-phase species and, thus, indirectly the nucleation of new fine particles, particularly in regions with significant air pollution. In this study, atmospheric particle concentrations are modeled for the North Sea and Baltic Sea regions in northwestern Europe using the Community Multiscale Air Quality (CMAQ modeling system and are compared to European Monitoring and Evaluation Programme (EMEP measurement data. The sea salt emission module is extended by a salinity-dependent scaling of the sea salt emissions because the salinity in large parts of the Baltic Sea is very low, which leads to considerably lower sea salt mass emissions compared to other oceanic regions. The resulting improvement in predicted sea salt concentrations is assessed. The contribution of surf zone emissions is considered separately. Additionally, the impacts of sea salt particles on atmospheric nitrate and ammonium concentrations and on nitrogen deposition are evaluated. The comparisons with observational data show that sea salt concentrations are commonly overestimated at coastal stations and partly underestimated farther inland. The introduced salinity scaling improves the predicted Baltic Sea sea salt concentrations considerably. The dates of measured peak concentrations are appropriately reproduced by the model. The impact of surf zone emissions is negligible in both seas. Nevertheless, they might be relevant because surf zone emissions were cut at an upper threshold in this study. Deactivating sea salt leads to minor increases in NH3 +  NH4+ and HNO3 +  NO3− and a decrease in NO3− concentrations. However, the overall effect on NH3 +  NH4+ and HNO3 +  NO3− concentrations is smaller than the deviation from the measurements. Nitrogen wet deposition is

Regional Atmospheric Transport Code for Hanford Emission Tracking, Version 2 (RATCHET2)

International Nuclear Information System (INIS)

Ramsdell, James V.; Rishel, Jeremy P.

2006-01-01

This manual describes the atmospheric model and computer code for the Atmospheric Transport Module within SAC. The Atmospheric Transport Module, called RATCHET2, calculates the time-integrated air concentration and surface deposition of airborne contaminants to the soil. The RATCHET2 code is an adaptation of the Regional Atmospheric Transport Code for Hanford Emissions Tracking (RATCHET). The original RATCHET code was developed to perform the atmospheric transport for the Hanford Environmental Dose Reconstruction Project. Fundamentally, the two sets of codes are identical; no capabilities have been deleted from the original version of RATCHET. Most modifications are generally limited to revision of the run-specification file to streamline the simulation process for SAC.

Regional Atmospheric Transport Code for Hanford Emission Tracking, Version 2(RATCHET2)

Energy Technology Data Exchange (ETDEWEB)

Ramsdell, James V.; Rishel, Jeremy P.

2006-07-01

This manual describes the atmospheric model and computer code for the Atmospheric Transport Module within SAC. The Atmospheric Transport Module, called RATCHET2, calculates the time-integrated air concentration and surface deposition of airborne contaminants to the soil. The RATCHET2 code is an adaptation of the Regional Atmospheric Transport Code for Hanford Emissions Tracking (RATCHET). The original RATCHET code was developed to perform the atmospheric transport for the Hanford Environmental Dose Reconstruction Project. Fundamentally, the two sets of codes are identical; no capabilities have been deleted from the original version of RATCHET. Most modifications are generally limited to revision of the run-specification file to streamline the simulation process for SAC.

Regional forecasting with global atmospheric models; Third year report

Energy Technology Data Exchange (ETDEWEB)

Crowley, T.J.; North, G.R.; Smith, N.R. [Applied Research Corp., College Station, TX (United States)

1994-05-01

This report was prepared by the Applied Research Corporation (ARC), College Station, Texas, under subcontract to Pacific Northwest Laboratory (PNL) as part of a global climate studies task. The task supports site characterization work required for the selection of a potential high-level nuclear waste repository and is part of the Performance Assessment Scientific Support (PASS) Program at PNL. The work is under the overall direction of the Office of Civilian Radioactive Waste Management (OCRWM), US Department of Energy Headquarters, Washington, DC. The scope of the report is to present the results of the third year`s work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain several studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals.

Analyzing and leveraging self-similarity for variable resolution atmospheric models

Science.gov (United States)

O'Brien, Travis; Collins, William

2015-04-01

Variable resolution modeling techniques are rapidly becoming a popular strategy for achieving high resolution in a global atmospheric models without the computational cost of global high resolution. However, recent studies have demonstrated a variety of resolution-dependent, and seemingly artificial, features. We argue that the scaling properties of the atmosphere are key to understanding how the statistics of an atmospheric model should change with resolution. We provide two such examples. In the first example we show that the scaling properties of the cloud number distribution define how the ratio of resolved to unresolved clouds should increase with resolution. We show that the loss of resolved clouds, in the high resolution region of variable resolution simulations, with the Community Atmosphere Model version 4 (CAM4) is an artifact of the model's treatment of condensed water (this artifact is significantly reduced in CAM5). In the second example we show that the scaling properties of the horizontal velocity field, combined with the incompressibility assumption, necessarily result in an intensification of vertical mass flux as resolution increases. We show that such an increase is present in a wide variety of models, including CAM and the regional climate models of the ENSEMBLES intercomparision. We present theoretical arguments linking this increase to the intensification of precipitation with increasing resolution.

Estimating regional carbon exchange in New England and Quebec by combining atmospheric, ground-based and satellite data

International Nuclear Information System (INIS)

Matross, Daniel M.; Pathmathevan, Mahadevan; Wofsy, Steven C.; Daube, Bruce C.; Gottlieb, Elaine W.; Chow, Victoria Y.; Munger, J.William; Lin, John C.

2006-01-01

We derive regional-scale (∼104 km 2 ) CO 2 flux estimates for summer 2004 in the northeast United States and southern Quebec by assimilating extensive data into a receptor-oriented model-data fusion framework. Surface fluxes are specified using the Vegetation Photosynthesis and Respiration Model (VPRM), a simple, readily optimized biosphere model driven by satellite data, AmeriFlux eddy covariance measurements and meteorological fields. The surface flux model is coupled to a Lagrangian atmospheric adjoint model, the Stochastic Time-Inverted Lagrangian Transport Model (STILT) that links point observations to upwind sources with high spatiotemporal resolution. Analysis of CO 2 concentration data from the NOAA-ESRL tall tower at Argyle, ME and from extensive aircraft surveys, shows that the STILT-VPRM framework successfully links model flux fields to regionally representative atmospheric CO 2 data, providing a bridge between 'bottom-up' and 'top-down' methods for estimating regional CO 2 budgets on timescales from hourly to monthly. The surface flux model, with initial calibration to eddy covariance data, produces an excellent a priori condition for inversion studies constrained by atmospheric concentration data. Exploratory optimization studies show that data from several sites in a region are needed to constrain model parameters for all major vegetation types, because the atmosphere commingles the influence of regional vegetation types, and even high-resolution meteorological analysis cannot disentangle the associated contributions. Airborne data are critical to help define uncertainty within the optimization framework, showing for example, that in summertime CO 2 concentration at Argyle (107 m) is ∼0.6 ppm lower than the mean in the planetary boundary layer

Development of regional atmospheric dynamic and air pollution models for nuclear emergency response system WSPEEDI

International Nuclear Information System (INIS)

Furuno, Akiko; Yamazawa, Hiromi; Lee, Soon-Hwan; Tsujita, Yuichi; Takemiya, Hiroshi; Chino, Masamichi

2000-01-01

WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information) is a computer-based emergency response system to predict long-range atmospheric dispersion of radionuclides discharged into the atmosphere due to a nuclear accident. WSPEEDI has been applied to several international exercises and real events. Through such experiences, the new version of WSPEEDI aims to employ a combination of an atmospheric dynamic model and a particle random walk model for more accurate predictions. This paper describes these models, improvement of prediction and computational techniques for quick responses. (author)

Comparing atmospheric transport models for future regional inversions over Europe - Part 1: mapping the atmospheric CO{sub 2} signals

Energy Technology Data Exchange (ETDEWEB)

Geels, C.; Brandt, J.; Christensen, J.H.; Frohn, L.M. [Univ Aarhus, Natl Environm Res Inst, DK-4000 Roskilde, (Denmark); Gloor, M. [Univ Leeds, Leeds, W Yorkshire, (United Kingdom); Ciais, P.; Bousquet, P.; Peylin, P.; Dargaville, R.; Ramonet, M. [CEA, CNRS, UMR 1572, Lab Sci Climat and Environm, F-91191 Gif Sur Yvette, (France); Vermeulen, A.T. [ECN, NL-1755 ZG Petten, (Netherlands); Aalto, T. [Finnish Meteorol Inst Air Qual Res, Helsinki 00810, (Finland); Haszpra, L. [Hungarian Meteorol Serv, H-1675 Budapest, (Hungary); Karstens, U.; Rodenbeck, C. [Max Planck Inst Biogeochem, D-07701 Jena, (Germany); Carboni, G. [CESI ApA, I-20134 Milan, (Italy); Santaguida, R. [Italian AF Meteorol Serv, I-41029 Sestola, MO, (Italy)

2007-07-01

The CO{sub 2} source and sink distribution across Europe can be estimated in principle through inverse methods by combining CO{sub 2} observations and atmospheric transport models. Uncertainties of such estimates are mainly due to insufficient spatio-temporal coverage of CO{sub 2} observations and biases of the models. In order to assess the biases related to the use of different models the CO{sub 2} concentration field over Europe has been simulated with five different Eulerian atmospheric transport models as part of the EU-funded AEROCARB project, which has the main goal to estimate the carbon balance of Europe. In contrast to previous comparisons, here both global coarse-resolution and regional higher-resolution models are included. Continuous CO{sub 2} observations from continental, coastal and mountain sites as well as flasks sampled on aircraft are used to evaluate the models ability to capture the spatio-temporal variability and distribution of lower troposphere CO{sub 2} across Europe. {sup 14}CO{sub 2} is used in addition to evaluate separately fossil fuel signal predictions. The simulated concentrations show a large range of variation, with up to similar to 10 ppm higher surface concentrations over Western and Central Europe in the regional models with highest (mesoscale) spatial resolution. The simulation-data comparison reveals that generally high-resolution models are more successful than coarse models in capturing the amplitude and phasing of the observed short-term variability. At high-altitude stations the magnitude of the differences between observations and models and in between models is less pronounced, but the timing of the diurnal cycle is not well captured by the models. The data comparisons show also that the timing of the observed variability on hourly to daily time scales at low-altitude stations is generally well captured by all models. However, the amplitude of the variability tends to be underestimated. While daytime values are quite

Comparing atmospheric transport models for future regional inversions over Europe ─ Part 1: mapping the atmospheric CO2 signals

Directory of Open Access Journals (Sweden)

M. Ramonet

2007-07-01

Full Text Available The CO2 source and sink distribution across Europe can be estimated in principle through inverse methods by combining CO2 observations and atmospheric transport models. Uncertainties of such estimates are mainly due to insufficient spatiotemporal coverage of CO2 observations and biases of the models. In order to assess the biases related to the use of different models the CO2 concentration field over Europe has been simulated with five different Eulerian atmospheric transport models as part of the EU-funded AEROCARB project, which has the main goal to estimate the carbon balance of Europe. In contrast to previous comparisons, here both global coarse-resolution and regional higher-resolution models are included. Continuous CO2 observations from continental, coastal and mountain sites as well as flasks sampled on aircrafts are used to evaluate the models' ability to capture the spatiotemporal variability and distribution of lower troposphere CO2 across Europe. 14CO2 is used in addition to evaluate separately fossil fuel signal predictions. The simulated concentrations show a large range of variation, with up to ~10 ppm higher surface concentrations over Western and Central Europe in the regional models with highest (mesoscale spatial resolution. The simulation – data comparison reveals that generally high-resolution models are more successful than coarse models in capturing the amplitude and phasing of the observed short-term variability. At high-altitude stations the magnitude of the differences between observations and models and in between models is less pronounced, but the timing of the diurnal cycle is not well captured by the models. The data comparisons show also that the timing of the observed variability on hourly to daily time scales at low-altitude stations is generally well captured by all models. However, the amplitude of the variability tends to be underestimated. While daytime values are quite well predicted, nighttime values are

AN ANALYTIC RADIATIVE-CONVECTIVE MODEL FOR PLANETARY ATMOSPHERES

International Nuclear Information System (INIS)

Robinson, Tyler D.; Catling, David C.

2012-01-01

We present an analytic one-dimensional radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power-law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric-pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries; (2) worlds with some attenuation of sunlight throughout the atmosphere, which we show can produce either shallow or deep radiative-convective boundaries, depending on the strength of sunlight attenuation; and (3) strongly irradiated giant planets (including hot Jupiters), where we explore the conditions under which these worlds acquire detached convective regions in their mid-tropospheres. Finally, we validate our model and demonstrate its utility through comparisons to the average observed thermal structure of Venus, Jupiter, and Titan, and by comparing computed flux profiles to more complex models.

Molecular absorption by atmospheric gases in the 100-1000 GHz region

Science.gov (United States)

Llewellyn-Jones, D. T.; Knight, R. J.

The two principal atmospheric absorbers in the near-mm wavelength region are oxygen and water vapor. In order to measure the degree of water vapor absorption with the required precision, a large untuned resonator was constructed, consisting of a copper cylindrical structure with a Q-value close to one million at 100 GHz. A comparison of observed absorption values with theoretical predictions show a marked discrepancy. Without laboratory measurements such as the present, existing atmospheric attenuation models are likely to be inaccurate and misleading, especially at the lower range of tropospheric temperatures.

Application of numerical environment system to regional atmospheric radioactivity transport simulations

International Nuclear Information System (INIS)

Yamazawa, H.; Ohkura, T.; Iida, T.; Chino, M.; Nagai, H.

2003-01-01

Main functions of the Numerical Environment System (NES), as a part of the Information Technology Based Laboratory (ITBL) project implemented by Japan Atomic Energy Research Institute, became available for test use purposes although the development of the system is still underway. This system consists of numerical models of meteorology and atmospheric dispersion, database necessary for model simulations, post- and pre-processors such as data conversion and visualization, and a suite of system software which provide the users with system functions through a web page access. The system utilizes calculation servers such as vector- and scalar-parallel processors for numerical model execution, a EWS which serves as a hub of the system. This system provides users in the field of nuclear emergency preparedness and atmospheric environment with easy-to-use functions of atmospheric dispersion simulations including input meteorological data preparation and visualization of simulation results. The performance of numerical models in the system was examined with observation data of long-range transported radon-222. The models in the system reproduced quite well temporal variations in the observed radon-222 concentrations in air which were caused by changes in the meteorological field in the synoptic scale. By applying the NES models in combination with the idea of backward-in-time atmospheric dispersion simulation, seasonal shift of source areas of radon-222 in the eastern Asian regions affecting the concentrations in Japan was quantitatively illustrated. (authors)

The increased atmospheric greenhouse effect and regional climate change

Energy Technology Data Exchange (ETDEWEB)

Groenaas, S. [Bergen Univ. (Norway)

1996-03-01

This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. The main information for predicting future climate changes comes from integrating coupled climate models of the atmosphere, ocean and cryosphere. Regional climate change may be studied from the global integrations, however, resolution is coarse because of insufficient computer power. Attempts are being made to get more regional details out of the global integrations by ``downscaling`` the latter. This can be done in two ways. Firstly, limited area models with high resolution are applied, driven by the global results as boundary values. Secondly, statistical relationships have been found between observed meteorological parameters, like temperature and precipitation, and analyzed large scale gridded fields. The derived relations are then used on similar data from climate runs to give local interpretations. A review is given of literature on recent observations of climate variations and on predicted regional climate change. 18 refs., 4 figs.

Improving Regional Forecast by Assimilating Atmospheric InfraRed Sounder (AIRS) Profiles into WRF Model

Science.gov (United States)

Chou, Shih-Hung; Zavodsky, Brad; Jedlovec, Gary J.

2009-01-01

In data sparse regions, remotely-sensed observations can be used to improve analyses and produce improved forecasts. One such source comes from the Atmospheric InfraRed Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), represents one of the most advanced space-based atmospheric sounding systems. The purpose of this paper is to describe a procedure to optimally assimilate high resolution AIRS profile data into a regional configuration of the Advanced Research WRF (ARW) version 2.2 using WRF-Var. The paper focuses on development of background error covariances for the regional domain and background type, and an optimal methodology for ingesting AIRS temperature and moisture profiles as separate overland and overwater retrievals with different error characteristics. The AIRS thermodynamic profiles are derived from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm and contain information about the quality of each temperature layer. The quality indicators were used to select the highest quality temperature and moisture data for each profile location and pressure level. The analyses were then used to conduct a month-long series of regional forecasts over the continental U.S. The long-term impacts of AIRS profiles on forecast were assessed against verifying NAM analyses and stage IV precipitation data.

Atmospheric circulation in regional climate models over Central Europe: links to surface air temperature and the influence of driving data

Czech Academy of Sciences Publication Activity Database

Plavcová, Eva; Kyselý, Jan

2012-01-01

Roč. 39, 7-8 (2012), s. 1681-1695 ISSN 0930-7575 R&D Project s: GA ČR GAP209/10/2265 Grant - others:ENSEMBLES: EU-FP6(XE) 505539 Program:FP6 Institutional support: RVO:68378289 Keywords : Regional climate models * Global climate models * Atmospheric circulation * Surface air temperature * ENSEMBLES * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 4.231, year: 2012 http://link.springer.com/article/10.1007%2Fs00382-011-1278-8#

Sensitivity of simulated regional Arctic climate to the choice of coupled model domain

Directory of Open Access Journals (Sweden)

Dmitry V. Sein

2014-07-01

Full Text Available The climate over the Arctic has undergone changes in recent decades. In order to evaluate the coupled response of the Arctic system to external and internal forcing, our study focuses on the estimation of regional climate variability and its dependence on large-scale atmospheric and regional ocean circulations. A global ocean–sea ice model with regionally high horizontal resolution is coupled to an atmospheric regional model and global terrestrial hydrology model. This way of coupling divides the global ocean model setup into two different domains: one coupled, where the ocean and the atmosphere are interacting, and one uncoupled, where the ocean model is driven by prescribed atmospheric forcing and runs in a so-called stand-alone mode. Therefore, selecting a specific area for the regional atmosphere implies that the ocean–atmosphere system can develop ‘freely’ in that area, whereas for the rest of the global ocean, the circulation is driven by prescribed atmospheric forcing without any feedbacks. Five different coupled setups are chosen for ensemble simulations. The choice of the coupled domains was done to estimate the influences of the Subtropical Atlantic, Eurasian and North Pacific regions on northern North Atlantic and Arctic climate. Our simulations show that the regional coupled ocean–atmosphere model is sensitive to the choice of the modelled area. The different model configurations reproduce differently both the mean climate and its variability. Only two out of five model setups were able to reproduce the Arctic climate as observed under recent climate conditions (ERA-40 Reanalysis. Evidence is found that the main source of uncertainty for Arctic climate variability and its predictability is the North Pacific. The prescription of North Pacific conditions in the regional model leads to significant correlation with observations, even if the whole North Atlantic is within the coupled model domain. However, the inclusion of the

Regional contributions of ocean iron fertilization to atmospheric CO2 changes during the last glacial termination

Science.gov (United States)

Opazo, N. E.; Lambert, F.

2017-12-01

Mineral dust aerosols affect climate directly by changing the radiative balance of the Earth, and indirectly by acting as cloud condensation nuclei and by affecting biogeochemical cycles. The impact on marine biogeochemical cycles is primarily through the supply of micronutrients such as iron to nutrient-limited regions of the oceans. Iron fertilization of High Nutrient Low Chlorophyll (HNLC) regions of the oceans is thought to have significantly affected the carbon cycle on glacial-interglacial scales and contributed about one fourth of the 80-100 ppm lowering of glacial atmospheric CO2 concentrations.In this study, we quantify the effect of global dust fluxes on atmospheric CO2 using the cGENIE model, an Earth System Model of Intermediate Complexity with emphasis on the carbon cycle. Global Holocene and Last Glacial Maximum (LGM) dust flux fields were obtained from both dust model simulations and reconstructions based on observational data. The analysis was performed in two stages. In the first instance, we produced 8 global intermediate dust flux fields between Holocene and LGM and simulated the atmospheric CO2 drawdown due to these 10 dust levels. In the second stage, we only changed dust flux levels in specific HNLC regions to isolate the effect of these ocean basins. We thus quantify the contribution of the South Atlantic, the South Pacific, the North Pacific, and the Central Pacific HNLC regions to the total atmospheric CO2 difference due to iron fertilization of the Earth's oceans.

Atmospheric Transport Modeling with 3D Lagrangian Dispersion Codes Compared with SF6 Tracer Experiments at Regional Scale

Directory of Open Access Journals (Sweden)

François Van Dorpe

2007-01-01

Full Text Available The results of four gas tracer experiments of atmospheric dispersion on a regional scale are used for the benchmarking of two atmospheric dispersion modeling codes, MINERVE-SPRAY (CEA, and NOSTRADAMUS (IBRAE. The main topic of this comparison is to estimate the Lagrangian code capability to predict the radionuclide atmospheric transfer on a large field, in the case of risk assessment of nuclear power plant for example. For the four experiments, the results of calculations show a rather good agreement between the two codes, and the order of magnitude of the concentrations measured on the soil is predicted. Simulation is best for sampling points located ten kilometers from the source, while we note a divergence for more distant points results (difference in concentrations by a factor 2 to 5. This divergence may be explained by the fact that, for these four experiments, only one weather station (near the point source was used on a field of 10 000 km2, generating the simulation of a uniform wind field throughout the calculation domain.

Modeling the global atmospheric transport and deposition of mercury to the Great Lakes

Directory of Open Access Journals (Sweden)

Mark D. Cohen

2016-07-01

Full Text Available Abstract Mercury contamination in the Great Lakes continues to have important public health and wildlife ecotoxicology impacts, and atmospheric deposition is a significant ongoing loading pathway. The objective of this study was to estimate the amount and source-attribution for atmospheric mercury deposition to each lake, information needed to prioritize amelioration efforts. A new global, Eulerian version of the HYSPLIT-Hg model was used to simulate the 2005 global atmospheric transport and deposition of mercury to the Great Lakes. In addition to the base case, 10 alternative model configurations were used to examine sensitivity to uncertainties in atmospheric mercury chemistry and surface exchange. A novel atmospheric lifetime analysis was used to characterize fate and transport processes within the model. Model-estimated wet deposition and atmospheric concentrations of gaseous elemental mercury (Hg(0 were generally within ∼10% of measurements in the Great Lakes region. The model overestimated non-Hg(0 concentrations by a factor of 2–3, similar to other modeling studies. Potential reasons for this disagreement include model inaccuracies, differences in atmospheric Hg fractions being compared, and the measurements being biased low. Lake Erie, downwind of significant local/regional emissions sources, was estimated by the model to be the most impacted by direct anthropogenic emissions (58% of the base case total deposition, while Lake Superior, with the fewest upwind local/regional sources, was the least impacted (27%. The U.S. was the largest national contributor, followed by China, contributing 25% and 6%, respectively, on average, for the Great Lakes. The contribution of U.S. direct anthropogenic emissions to total mercury deposition varied between 46% for the base case (with a range of 24–51% over all model configurations for Lake Erie and 11% (range 6–13% for Lake Superior. These results illustrate the importance of atmospheric

Regional Ocean Modeling System (ROMS): Main Hawaiian Islands

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 7-day, 3-hourly forecast for the region surrounding the main Hawaiian islands at approximately 4-km resolution. While...

Regional Ocean Modeling System (ROMS): CNMI: Data Assimilating

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 3-day, 3-hourly data assimilating hindcast for the region surrounding the Commonwealth of the Northern Mariana Islands (CNMI)...

Impact of surface waves in a Regional Climate Model

DEFF Research Database (Denmark)

Rutgersson, Anna; Sætra, Oyvind; Semedo, Alvaro

2010-01-01

A coupled regional atmosphere-wave model system is developed with the purpose of investigating the impact of climate changes on the wave field, as well as feed-back effects of the wave field on the atmospheric parameters. This study focuses on the effects of introducing a two-way atmosphere...

Impact of marine mercury cycling on coastal atmospheric mercury concentrations in the North- and Baltic Sea region

Directory of Open Access Journals (Sweden)

Johannes Bieser

2016-06-01

Full Text Available Abstract The cycling of mercury between ocean and atmosphere is an important part of the global Hg cycle. Here we study the regional contribution of the air-sea exchange in the North- and Baltic Sea region. We use a newly developed coupled regional chemistry transport modeling (CTM system to determine the flux between atmosphere and ocean based on the meteorological model COSMO-CLM, the ocean-ecosystem model ECOSMO, the atmospheric CTM CMAQ and a newly developed module for mercury partitioning and speciation in the ocean (MECOSMO. The model was evaluated using atmospheric observations of gaseous elemental mercury (GEM, surface concentrations of dissolved gaseous mercury (DGM, and air-sea flux (ASF calculations based on observations made on seven cruises in the western and central Baltic Sea and three cruises in the North Sea performed between 1991 and 2006. It was shown that the model is in good agreement with observations: DGM (Normalized Mean Bias NMB=-0.27 N=413, ASF (NMB=-0.32, N=413, GEM (NMB=0.07, N=2359. Generally, the model was able to reproduce the seasonal DGM cycle with the best agreement during winter and autumn (NMBWinter=-0.26, NMBSpring=-0.41, NMBSummer=-0.29, NMBAutumn=-0.03. The modelled mercury evasion from the Baltic Sea ranged from 3400 to 4000 kg/a for the simulation period 1994–2007 which is on the lower end of previous estimates. Modelled atmospheric deposition, river inflow and air-sea exchange lead to an annual net Hg accumulation in the Baltic Sea of 500 to 1000 kg/a. For the North Sea the model calculates an annual mercury flux into the atmosphere between 5700 and 6000 kg/a. The mercury flux from the ocean influenced coastal atmospheric mercury concentrations. Running CMAQ coupled with the ocean model lead to better agreement with GEM observations. Directly at the coast GEM concentrations could be increased by up to 10% on annual average and observed peaks could be reproduced much better. At stations 100km downwind

ESA STSE “SST Diurnal Variability: Regional Extend - Implications in Atmospheric Modelling”

DEFF Research Database (Denmark)

Karagali, Ioanna

The diurnal variability of SST, driven by the coincident occurrence of low enough wind and solar heating, has been observed in various regions of the global ocean [4, 5, 6]. Atmospheric, oceanic and climate models are not adequately resolving the daily SST cycle, resulting in biases of the total...

Regional Ocean Modeling System (ROMS): Samoa: Data Assimilating

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 3-day, 3-hourly data assimilating hindcast for the region surrounding the islands of Samoa at approximately 3-km resolution....

Regional Ocean Modeling System (ROMS): Oahu: Data Assimilating

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 2-day, 3-hourly data assimilating hindcast for the region surrounding the island of Oahu at approximately 1-km resolution....

The Brazilian Developments on the Regional Atmospheric Modeling System (BRAMS 5.2): An Integrated Environmental Model Tuned for Tropical Areas

Science.gov (United States)

Freitas, Saulo R.; Panetta, Jairo; Longo, Karla M.; Rodrigues, Luiz F.; Moreira, Demerval S.; Rosario, Nilton E.; Silva Dias, Pedro L.; Silva Dias, Maria A. F.; Souza, Enio P.; Freitas, Edmilson D.;

A conceptual prediction model for seasonal drought processes using atmospheric and oceanic standardized anomalies: application to regional drought processes in China

Science.gov (United States)

Liu, Zhenchen; Lu, Guihua; He, Hai; Wu, Zhiyong; He, Jian

2018-01-01

Reliable drought prediction is fundamental for water resource managers to develop and implement drought mitigation measures. Considering that drought development is closely related to the spatial-temporal evolution of large-scale circulation patterns, we developed a conceptual prediction model of seasonal drought processes based on atmospheric and oceanic standardized anomalies (SAs). Empirical orthogonal function (EOF) analysis is first applied to drought-related SAs at 200 and 500 hPa geopotential height (HGT) and sea surface temperature (SST). Subsequently, SA-based predictors are built based on the spatial pattern of the first EOF modes. This drought prediction model is essentially the synchronous statistical relationship between 90-day-accumulated atmospheric-oceanic SA-based predictors and SPI3 (3-month standardized precipitation index), calibrated using a simple stepwise regression method. Predictor computation is based on forecast atmospheric-oceanic products retrieved from the NCEP Climate Forecast System Version 2 (CFSv2), indicating the lead time of the model depends on that of CFSv2. The model can make seamless drought predictions for operational use after a year-to-year calibration. Model application to four recent severe regional drought processes in China indicates its good performance in predicting seasonal drought development, despite its weakness in predicting drought severity. Overall, the model can be a worthy reference for seasonal water resource management in China.

Southeast Atmosphere Studies: learning from model-observation syntheses

Directory of Open Access Journals (Sweden)

J. Mao

2018-02-01

Full Text Available Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and

Southeast Atmosphere Studies: learning from model-observation syntheses

Science.gov (United States)

Mao, Jingqiu; Carlton, Annmarie; Cohen, Ronald C.; Brune, William H.; Brown, Steven S.; Wolfe, Glenn M.; Jimenez, Jose L.; Pye, Havala O. T.; Ng, Nga Lee; Xu, Lu; McNeill, V. Faye; Tsigaridis, Kostas; McDonald, Brian C.; Warneke, Carsten; Guenther, Alex; Alvarado, Matthew J.; de Gouw, Joost; Mickley, Loretta J.; Leibensperger, Eric M.; Mathur, Rohit; Nolte, Christopher G.; Portmann, Robert W.; Unger, Nadine; Tosca, Mika; Horowitz, Larry W.

2018-02-01

Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS) conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA) and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and elsewhere. Here we

Simulating forest productivity and surface-atmosphere carbon exchange in the BOREAS study region

Energy Technology Data Exchange (ETDEWEB)

Kimball, J.S.; Thornton, P.E.; White, M.A.; Running, S.W. [Montana Univ., Missoula, MT (United States). School of Forestry

1997-12-31

Studies have shown that the boreal forest region is in danger of experiencing significant warming and drying in response to increases in atmospheric CO{sub 2} concentration and other greenhouse gases. Since the boreal forest region contains 16-24 per cent of the world`s soil carbon, warming in this region could result in a rapid, large-scale displacement and redistribution of boreal forest, enhanced release of CO{sub 2} to the atmosphere, and an intensification of global warming. A study was conducted in which a process-based, general ecosystem model (BIOME-BGC) was used to simulate daily gross primary production, maintenance and heterotrophic respiration, net primary production and net ecosystem carbon exchange of boreal aspen, jack pine and black spruce. The objective was to integrate point measurements across multiple spatial and temporal scales using process level models of the boreal forest water, energy and biogeochemical cycles. Climate characteristics that control simulated carbon fluxes were also studied. Results showed that trees with large daily evapotranspiration rates and those situated on sandy soils with low water holding capacities were especially vulnerable to increased temperature and drought conditions. Trees subject to frequent water stress during the growing season, particularly older trees that exhibit low photosynthetic and high respiration rates, were on the margin between being annual net sources or sinks for atmospheric carbon. 71 refs., 3 tabs., 5 figs.

Regional Ocean Modeling System (ROMS): Oahu South Shore

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 2-day, 3-hourly forecast for the region surrounding the south shore of the island of Oahu at approximately 200-m resolution....

Atmospheric Environment Vulnerability Cause Analysis for the Beijing-Tianjin-Hebei Metropolitan Region.

Science.gov (United States)

Zhang, Yang; Shen, Jing; Li, Yu

2018-01-13

Assessing and quantifying atmospheric vulnerability is a key issue in urban environmental protection and management. This paper integrated the Analytical hierarchy process (AHP), fuzzy synthesis evaluation and Geographic Information System (GIS) spatial analysis into an Exposure-Sensitivity-Adaptive capacity (ESA) framework to quantitatively assess atmospheric environment vulnerability in the Beijing-Tianjin-Hebei (BTH) region with spatial and temporal comparisons. The elaboration of the relationships between atmospheric environment vulnerability and indices of exposure, sensitivity, and adaptive capacity supports enable analysis of the atmospheric environment vulnerability. Our findings indicate that the atmospheric environment vulnerability of 13 cities in the BTH region exhibits obvious spatial heterogeneity, which is caused by regional diversity in exposure, sensitivity, and adaptive capacity indices. The results of atmospheric environment vulnerability assessment and the cause analysis can provide guidance to pick out key control regions and recognize vulnerable indicators for study sites. The framework developed in this paper can also be replicated at different spatial and temporal scales using context-specific datasets to support environmental management.

Retrieval Assimilation and Modeling of Atmospheric Water Vapor from Ground- and Space-Based GPS Networks: Investigation of the Global and Regional Hydrological Cycles

Science.gov (United States)

Dickey, Jean O.

1999-01-01

Uncertainty over the response of the atmospheric hydrological cycle (particularly the distribution of water vapor and cloudiness) to anthropogenic forcing is a primary source of doubt in current estimates of global climate sensitivity, which raises severe difficulties in evaluating its likely societal impact. Fortunately, a variety of advanced techniques and sensors are beginning to shed new light on the atmospheric hydrological cycle. One of the most promising makes use of the sensitivity of the Global Positioning System (GPS) to the thermodynamic state, and in particular the water vapor content, of the atmosphere through which the radio signals propagate. Our strategy to derive the maximum benefit for hydrological studies from the rapidly increasing GPS data stream will proceed in three stages: (1) systematically analyze and archive quality-controlled retrievals using state-of-the-art techniques; (2) employ both currently available and innovative assimilation procedures to incorporate these determinations into advanced regional and global atmospheric models and assess their effects; and (3) apply the results to investigate selected scientific issues of relevance to regional and global hydrological studies. An archive of GPS-based estimation of total zenith delay (TZD) data and water vapor where applicable has been established with expanded automated quality control. The accuracy of the GPS estimates is being monitored; the investigation of systematic errors is ongoing using comparisons with water vapor radiometers. Meteorological packages have been implemented. The accuracy and utilization of the TZD estimates has been improved by implementing a troposphere gradient model. GPS-based gradients have been validated as real atmospheric moisture gradients, establishing a link between the estimated gradients and the passage of weather fronts. We have developed a generalized ray tracing inversion scheme that can be used to analyze occultation data acquired from space

Users guide to REGIONAL-1: a regional assessment model

International Nuclear Information System (INIS)

Davis, W.E.; Eadie, W.J.; Powell, D.C.

1979-09-01

A guide was prepared to allow a user to run the PNL long-range transport model, REGIONAL 1. REGIONAL 1 is a computer model set up to run atmospheric assessments on a regional basis. The model has the capability of being run in three modes for a single time period. The three modes are: (1) no deposition, (2) dry deposition, (3) wet and dry deposition. The guide provides the physical and mathematical basis used in the model for calculating transport, diffusion, and deposition for all three modes. Also the guide includes a program listing with an explanation of the listings and an example in the form of a short-term assessment for 48 hours. The purpose of the example is to allow a person who has past experience with programming and meteorology to operate the assessment model and compare his results with the guide results. This comparison will assure the user that the program is operating in a proper fashion

Multiple climate regimes in an idealized lake-ice-atmosphere model

Science.gov (United States)

Sugiyama, Noriyuki; Kravtsov, Sergey; Roebber, Paul

2018-01-01

In recent decades, the Laurentian Great Lakes have undergone rapid surface warming with the summertime trends substantially exceeding the warming rates of surrounding land. Warming of the deepest (Lake Superior) was the strongest, and that of the shallowest (Lake Erie)—the weakest of all lakes. To investigate the dynamics of accelerated lake warming, we considered single-column and multi-column thermodynamic lake-ice models coupled to an idealized two-layer atmosphere. The variable temperature of the upper atmospheric layer—a proxy for the large-scale atmospheric forcing—consisted, in the most general case, of a linear trend mimicking the global warming and atmospheric interannual variability, both on top of the prescribed seasonal cycle of the upper-air temperature. The atmospheric boundary layer of the coupled model exchanged heat with the lake and exhibited lateral diffusive heat transports between the adjacent atmospheric columns. In simpler single-column models, we find that, for a certain range of periodic atmospheric forcing, each lake possesses two stable equilibrium seasonal cycles, which we call "regimes"—with and without lake-ice occurrence in winter and with corresponding cold and warm temperatures in the following summer, respectively, all under an identical seasonally varying external forcing. Deeper lakes exhibit larger differences in their summertime surface water temperature between the warm and cold regimes, due to their larger thermal and dynamical inertia. The regime behavior of multi-column coupled models is similar but more complex, and in some cases, they admit more than two stable equilibrium seasonal cycles, with varying degrees of wintertime ice-cover. The simulated lake response to climate change in the presence of the atmospheric noise rationalizes the observed accelerated warming of the lakes, the correlation between wintertime ice cover and next summer's lake-surface temperature, as well as higher warming trends of the

Greenhouse gases regional fluxes estimated from atmospheric measurements

International Nuclear Information System (INIS)

Messager, C.

2007-07-01

build up a new system to measure continuously CO 2 (or CO), CH 4 , N 2 O and SF 6 mixing ratios. It is based on a commercial gas chromatograph (Agilent 6890N) which have been modified to reach better precision. Reproducibility computed with a target gas on a 24 hours time step gives: 0.06 ppm for CO 2 , 1.4 ppb for CO, 0.7 ppb for CH 4 , 0.2 ppb for N 2 O and 0.05 ppt for SF 6 . The instrument's run is fully automated, an air sample analysis takes about 5 minutes. In July 2006, I install instrumentation on a telecommunication tall tower (200 m) situated near Orleans forest in Trainou, to monitor continuously greenhouse gases (CO 2 , CH 4 , N 2 O, SF 6 ), atmospheric tracers (CO, Radon-222) and meteorological parameters. Intake lines were installed at 3 levels (50, 100 and 180 m) and allow us to sample air masses along the vertical. Continuous measurement started in January 2007. I used Mace Head (Ireland) and Gif-sur-Yvette continuous measurements to estimate major greenhouse gases emission fluxes at regional scale. To make the link between atmospheric measurements and surface fluxes, we need to quantify dilution due to atmospheric transport. I used Radon-222 as tracer (radon tracer method) and planetary boundary layer heights estimates from ECMWF model (boundary layer budget method) to parameterize atmospheric transport. In both cases I compared results to available emission inventories. (author)

Atmospheric water budget over the South Asian summer monsoon region

Science.gov (United States)

Unnikrishnan, C. K.; Rajeevan, M.

2018-04-01

High resolution hybrid atmospheric water budget over the South Asian monsoon region is examined. The regional characteristics, variability, regional controlling factors and the interrelations of the atmospheric water budget components are investigated. The surface evapotranspiration was created using the High Resolution Land Data Assimilation System (HRLDAS) with the satellite-observed rainfall and vegetation fraction. HRLDAS evapotranspiration shows significant similarity with in situ observations and MODIS satellite-observed evapotranspiration. Result highlights the fundamental importance of evapotranspiration over northwest and southeast India on atmospheric water balance. The investigation shows that the surface net radiation controls the annual evapotranspiration over those regions, where the surface evapotranspiration is lower than 550 mm. The rainfall and evapotranspiration show a linear relation over the low-rainfall regions (forcing (like surface net radiation). The lead and lag correlation of water budget components show that the water budget anomalies are interrelated in the monsoon season even up to 4 months lead. These results show the important regional interrelation of water budget anomalies on south Asian monsoon.

The use of an atmospheric dispersion model to determine influence regions in the Prince George, B.C. airshed from the burning of open wood waste piles.

Science.gov (United States)

Ainslie, B; Jackson, P L

2009-06-01

A means of determining air emission source regions adversely influencing the city of Prince George, British Columbia, Canada from potential burning of isolated piles of mountain pine beetle-killed lodge pole pine is presented. The analysis uses the CALPUFF atmospheric dispersion model to identify safe burning regions based on atmospheric stability and wind direction. Model results show that the location and extent of influence regions is sensitive to wind speed, wind direction, atmospheric stability and a threshold used to quantify excessive concentrations. A concentration threshold based on the Canada Wide PM(2.5) Standard is used to delineate the influence regions while Environment Canada's (EC) daily ventilation index (VI) is used to quantify local atmospheric stability. Results from the analysis, to be used by air quality meteorologists in assessing daily requests for burning permits, are presented as a series of maps delineating acceptable burning locations for sources placed at various distances from the city center and under different ventilation conditions. The results show that no burning should be allowed within 10 km of the city center; under poor ventilation conditions, no burning should be allowed within 20 km of the city center; under good ventilation conditions, burning can be allowed within 10-15 km of the city center; under good to fair ventilation conditions, burning can be allowed beyond 15 km of the city center; and if the wind direction can be reliably forecast, burning can be allowed between 5 and 10 km downwind of the city center under good ventilation conditions.

Atmospheric correction using near-infrared bands for satellite ocean color data processing in the turbid western Pacific region.

Science.gov (United States)

Wang, Menghua; Shi, Wei; Jiang, Lide

2012-01-16

A regional near-infrared (NIR) ocean normalized water-leaving radiance (nL(w)(λ)) model is proposed for atmospheric correction for ocean color data processing in the western Pacific region, including the Bohai Sea, Yellow Sea, and East China Sea. Our motivation for this work is to derive ocean color products in the highly turbid western Pacific region using the Geostationary Ocean Color Imager (GOCI) onboard South Korean Communication, Ocean, and Meteorological Satellite (COMS). GOCI has eight spectral bands from 412 to 865 nm but does not have shortwave infrared (SWIR) bands that are needed for satellite ocean color remote sensing in the turbid ocean region. Based on a regional empirical relationship between the NIR nL(w)(λ) and diffuse attenuation coefficient at 490 nm (K(d)(490)), which is derived from the long-term measurements with the Moderate-resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, an iterative scheme with the NIR-based atmospheric correction algorithm has been developed. Results from MODIS-Aqua measurements show that ocean color products in the region derived from the new proposed NIR-corrected atmospheric correction algorithm match well with those from the SWIR atmospheric correction algorithm. Thus, the proposed new atmospheric correction method provides an alternative for ocean color data processing for GOCI (and other ocean color satellite sensors without SWIR bands) in the turbid ocean regions of the Bohai Sea, Yellow Sea, and East China Sea, although the SWIR-based atmospheric correction approach is still much preferred. The proposed atmospheric correction methodology can also be applied to other turbid coastal regions.

Improved PPP Ambiguity Resolution Considering the Stochastic Characteristics of Atmospheric Corrections from Regional Networks

Science.gov (United States)

Li, Yihe; Li, Bofeng; Gao, Yang

2015-01-01

With the increased availability of regional reference networks, Precise Point Positioning (PPP) can achieve fast ambiguity resolution (AR) and precise positioning by assimilating the satellite fractional cycle biases (FCBs) and atmospheric corrections derived from these networks. In such processing, the atmospheric corrections are usually treated as deterministic quantities. This is however unrealistic since the estimated atmospheric corrections obtained from the network data are random and furthermore the interpolated corrections diverge from the realistic corrections. This paper is dedicated to the stochastic modelling of atmospheric corrections and analyzing their effects on the PPP AR efficiency. The random errors of the interpolated corrections are processed as two components: one is from the random errors of estimated corrections at reference stations, while the other arises from the atmospheric delay discrepancies between reference stations and users. The interpolated atmospheric corrections are then applied by users as pseudo-observations with the estimated stochastic model. Two data sets are processed to assess the performance of interpolated corrections with the estimated stochastic models. The results show that when the stochastic characteristics of interpolated corrections are properly taken into account, the successful fix rate reaches 93.3% within 5 min for a medium inter-station distance network and 80.6% within 10 min for a long inter-station distance network. PMID:26633400

Critical review of studies on atmospheric dispersion in coastal regions

International Nuclear Information System (INIS)

Shearer, D.L.; Kaleel, R.J.

1982-09-01

This study effort was required as a preliminary step prior to initiation of field measurements of atmospheric dispersion in coastal regions. The Nuclear Regulatory Commission (NRC) is in the process of planning an extensive field measurement program to generate data which will serve as improved data bases for licensing decisions, confirmation of regulations, standards, and guides, and for site characterizations. The study being reported here is an effort directed to obtaining as much information as is possible from existing studies that is relevant toward NRC's objectives. For this study, reports covering research and meteorological measurements conducted for industrial purposes, utility needs, military objectives, and academic studies were obtained and critically reviewed in light of NRC's current data needs. This report provides an interpretation of the extent of existing usable information, an indication of the potential for tailoring existing research toward current NRC information needs, and recommendations for several follow-on studies which could provide valuable additional information through reanalysis of the data. Recommendations are also offered regarding new measurement programs. Emphasis is placed on the identification and acquisition of data from atmospheric tracer studies conducted in coastal regions. A total of 225 references were identified which deal with the coastal atmosphere, including meteorological and tracer measurement programs, theoretical descriptions of the relevant processes, and dispersion models

Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

Energy Technology Data Exchange (ETDEWEB)

Al Razi, Khandakar Md Habib; Hiroshi, Moritomi; Shinji, Kambara [Environmental and Renewable Energy System (ERES), Graduate School of Engineering, Gifu University, Yanagido, Gifu City, 501-1193 (Japan)

2012-07-01

The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environmental concern. Identification of sources contributing to the high atmospheric mercury levels will be useful for formulating pollution control and mitigation strategies in the region. In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of 'Substances Requiring Priority Action' published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 ?g/m3. Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER) that estimates regional atmospheric concentration and distribution. The second is the Hybrid Single Particle Lagrangian Integrated trajectory Model (HYSPLIT) that estimates the atmospheric

North American Carbon Project (NACP) Regional Model-Model and Model-Data Intercomparison Project

Science.gov (United States)

Huntzinger, D. N.; Post, W. M.; Jacobson, A. R.; Cook, R. B.

2009-05-01

Available observations are localized and widely separated in both space and time, so we depend heavily on models to characterize, understand, and predict carbon fluxes at regional and global scales. The results from each model differ because they use different approaches (forward vs. inverse), modeling strategies (detailed process, statistical, observation based), process representation, boundary conditions, initial conditions, and driver data. To investigate these differences we conducted a model-model and model-data comparison using available forward ecosystem model and atmospheric inverse output, along with regional scale inventory data. Forward or "bottom-up" models typically estimate carbon fluxes through a set of physiological relationships, and are based on our current mechanistic understanding of how carbon is exchanged within ecosystems. Inverse or "top-down" analyses use measured atmospheric concentrations of CO2, coupled with an atmospheric transport model to infer surface flux distributions. Although bottom-up models do fairly well at reproducing measured fluxes (i.e., net ecosystem exchange) at a given location, they vary considerably in their estimates of carbon flux over regional or continental scales, suggesting difficulty in scaling mechanistic relationships to large areas and/or timescales. Conversely, top-down inverse models predict fluxes that are quantitatively consistent with atmospheric measurements, suggesting that they are capturing large scale variability in flux quite well, but offer limited insights into the processes controlling this variability and how fluxes vary at fine spatial scales. The analyses focused on identifying and quantifying spatial and temporal patterns of carbon fluxes among the models; quantifying across-model variability, as well as comparing simulated or estimated surface fluxes and biomass to observed values at regional to continental scales for the period 2000-2005. The analysis focused on the following three

Preliminary assessment of the performance of a global coupled atmosphere-ocean model

International Nuclear Information System (INIS)

Cubasch, U.

1990-01-01

A low-resolution version of the ECMWF global atmosphere model has been coupled to a global ocean model developed at the Max Planck Institute in Hamburg. The atmosphere model is driven by the sea surface temperature and the ice thickness calculated by the ocean model, which, in return, is driven by the wind stress, the heat flux and the freshwater flux diagnosed by the atmosphere model. Even though each model reaches stationarity when integrated on its own, the coupling of both creates problems, since the fields calculated by each model are not consistent with the ones the other model has to have in order to stay stationary, because some of the fluxes are not balanced. In the coupled experiment the combined ocean-atmosphere system drifts toward a colder state. To counteract this problem, a flux correction has been applied which balances the mean biases of each model. This method almost eliminates the climate drift of the coupled model. Problems still arise over ice covered regions

Impacts of regional land-grab on regional hydroclimate in southeastern Africa via modeling and remote sensing

Science.gov (United States)

Maksimowicz, M.; Masarik, M. T.; Brandt, J.; Flores, A. N.

2017-12-01

Land use/land cover (LULC) change directly impacts the partitioning of surface mass and energy fluxes. Regional-scale weather and climate are potentially altered by LULC if the resultant changes in partitioning of surface energy fluxes are significant enough to induce changes in the evolution of the planetary boundary layer and its interaction with the atmosphere above. Dynamics of land use, particularly those related to the social dimensions of the Earth System, are often simplified or not represented in regional land-atmosphere models or Earth System Models. This study explores the role of LULC change on a regional hydroclimate system, focusing on potential hydroclimate changes arising from timber harvesting due to a land grab boom in Mozambique. We also focus more narrowly at quantifying regional impacts on Gorongosa National Park, a nationally important economic and biodiversity resource in southeastern Africa. After nationalizing all land in 1975 after Mozambique gained independence, complex social processes, including an extended low intensity conflict civil war and economic hardships, led to an escalation of land use rights grants to foreign governments. Between 2004 and 2009, large tracts of land were requested for timber. Here we use existing tree cover loss datasets to more accurately represent land cover within a regional weather model. LULC in a region encompassing Gorongosa is updated at three instances between 2001 and 2014 using a tree cover loss dataset. We use these derived LULC datasets to inform lower boundary conditions in the Weather Research and Forecasting (WRF) model. To quantify potential hydrometeorological changes arising from land use change, we performed a factorial-like experiment by mixing input LULC maps and atmospheric forcing data from before, during, and after the land grab. Results suggest that the land grab has impacted microclimate parameters in a significant way via direct and indirect impacts on land-atmosphere interactions

The 1-way on-line coupled atmospheric chemistry model system MECO(n – Part 1: Description of the limited-area atmospheric chemistry model COSMO/MESSy

Directory of Open Access Journals (Sweden)

A. Kerkweg

2012-01-01

Full Text Available The numerical weather prediction model of the Consortium for Small Scale Modelling (COSMO, maintained by the German weather service (DWD, is connected with the Modular Earth Submodel System (MESSy. This effort is undertaken in preparation of a new, limited-area atmospheric chemistry model. Limited-area models require lateral boundary conditions for all prognostic variables. Therefore the quality of a regional chemistry model is expected to improve, if boundary conditions for the chemical constituents are provided by the driving model in consistence with the meteorological boundary conditions. The new developed model is as consistent as possible, with respect to atmospheric chemistry and related processes, with a previously developed global atmospheric chemistry general circulation model: the ECHAM/MESSy Atmospheric Chemistry (EMAC model. The combined system constitutes a new research tool, bridging the global to the meso-γ scale for atmospheric chemistry research. MESSy provides the infrastructure and includes, among others, the process and diagnostic submodels for atmospheric chemistry simulations. Furthermore, MESSy is highly flexible allowing model setups with tailor made complexity, depending on the scientific question. Here, the connection of the MESSy infrastructure to the COSMO model is documented and also the code changes required for the generalisation of regular MESSy submodels. Moreover, previously published prototype submodels for simplified tracer studies are generalised to be plugged-in and used in the global and the limited-area model. They are used to evaluate the TRACER interface implementation in the new COSMO/MESSy model system and the tracer transport characteristics, an important prerequisite for future atmospheric chemistry applications. A supplementary document with further details on the technical implementation of the MESSy interface into COSMO with a complete list of modifications to the COSMO code is provided.

Refining multi-model projections of temperature extremes by evaluation against land-atmosphere coupling diagnostics

Science.gov (United States)

Sippel, Sebastian; Zscheischler, Jakob; Mahecha, Miguel D.; Orth, Rene; Reichstein, Markus; Vogel, Martha; Seneviratne, Sonia I.

2017-05-01

The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land-atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land-atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T) and evapotranspiration (ET) benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land-atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5) archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET) are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T-ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T-ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand, the differences between projected

Quality assessment of atmospheric surface fields over the Baltic Sea from an ensemble of regional climate model simulations with respect to ocean dynamics

Directory of Open Access Journals (Sweden)

H. E. Markus Meier

2011-05-01

Full Text Available Climate model results for the Baltic Sea region from an ensemble of eight simulations using the Rossby Centre Atmosphere model version 3 (RCA3 driven with lateral boundary data from global climate models (GCMs are compared with results from a downscaled ERA40 simulation and gridded observations from 1980-2006. The results showed that data from RCA3 scenario simulations should not be used as forcing for Baltic Sea models in climate change impact studies because biases of the control climate significantly affect the simulated changes of future projections. For instance, biases of the sea ice cover in RCA3 in the present climate affect the sensitivity of the model's response to changing climate due to the ice-albedo feedback. From the large ensemble of available RCA3 scenario simulations two GCMs with good performance in downscaling experiments during the control period 1980-2006 were selected. In this study, only the quality of atmospheric surface fields over the Baltic Sea was chosen as a selection criterion. For the greenhouse gas emission scenario A1B two transient simulations for 1961-2100 driven by these two GCMs were performed using the regional, fully coupled atmosphere-ice-ocean model RCAO. It was shown that RCAO has the potential to improve the results in downscaling experiments driven by GCMs considerably, because sea surface temperatures and sea ice concentrations are calculated more realistically with RCAO than when RCA3 has been forced with surface boundary data from GCMs. For instance, the seasonal 2 m air temperature cycle is closer to observations in RCAO than in RCA3 downscaling simulations. However, the parameterizations of air-sea fluxes in RCAO need to be improved.

Estimation of Regional Carbon Balance from Atmospheric Observations

Science.gov (United States)

Denning, S.; Uliasz, M.; Skidmore, J.

2002-12-01

Variations in the concentration of CO2 and other trace gases in time and space contain information about sources and sinks at regional scales. Several methods have been developed to quantitatively extract this information from atmospheric measurements. Mass-balance techniques depend on the ability to repeatedly sample the same mass of air, which involves careful attention to airmass trajectories. Inverse and adjoint techniques rely on decomposition of the source field into quasi-independent "basis functions" that are propagated through transport models and then used to synthesize optimal linear combinations that best match observations. A recently proposed method for regional flux estimation from continuous measurements at tall towers relies on time-mean vertical gradients, and requires careful trajectory analysis to map the estimates onto regional ecosystems. Each of these techniques is likely to be applied to measurements made during the North American Carbon Program. We have also explored the use of Bayesian synthesis inversion at regional scales, using a Lagrangian particle dispersion model driven by mesoscale transport fields. Influence functions were calculated for each hypothetical observation in a realistic diurnally-varying flow. These influence functions were then treated as basis functions for the purpose of separate inversions for daytime photosynthesis and 24-hour mean ecosystem respiration. Our results highlight the importance of estimating CO2 fluxes through the lateral boundaries of the model. Respiration fluxes were well constrained by one or two hypothetical towers, regardless of inflow fluxes. Time-varying assimilation fluxes were less well constrained, and much more dependent on knowledge of inflow fluxes. The small net difference between respiration and photosynthesis was the most difficult to determine, being extremely sensitive to knowledge of inflow fluxes. Finally, we explored the feasibility of directly incorporating mid-day concentration

Grassland/atmosphere response to changing climate: Coupling regional and local scales

International Nuclear Information System (INIS)

Coughenour, M.B.; Kittel, T.G.F.; Pielke, R.A.; Eastman, J.

1993-10-01

The objectives of the study were: to evaluate the response of grassland ecosystems to atmospheric change at regional and site scales, and to develop multiscaled modeling systems to relate ecological and atmospheric models with different spatial and temporal resolutions. A menu-driven shell was developed to facilitate use of models at different temporal scales and to facilitate exchange information between models at different temporal scales. A detailed ecosystem model predicted that C 3 temperate grasslands wig respond more strongly to elevated CO 2 than temperate C 4 grasslands in the short-term while a large positive N-PP response was predicted for a C 4 Kenyan grassland. Long-term climate change scenarios produced either decreases or increases in Colorado plant productivity (NPP) depending on rainfall, but uniform increases in N-PP were predicted in Kenya. Elevated CO 2 is likely to have little effect on ecosystem carbon storage in Colorado while it will increase carbon storage in Kenya. A synoptic climate classification processor (SCP) was developed to evaluate results of GCM climate sensitivity experiments. Roughly 80% agreement was achieved with manual classifications. Comparison of lx and 2xCO 2 GCM Simulations revealed relatively small differences

Sources of Sahelian-Sudan moisture: Insights from a moisture-tracing atmospheric model

Science.gov (United States)

Salih, Abubakr A. M.; Zhang, Qiong; Pausata, Francesco S. R.; Tjernström, Michael

2016-07-01

The summer rainfall across Sahelian-Sudan is one of the main sources of water for agriculture, human, and animal needs. However, the rainfall is characterized by large interannual variability, which has attracted extensive scientific efforts to understand it. This study attempts to identify the source regions that contribute to the Sahelian-Sudan moisture budget during July through September. We have used an atmospheric general circulation model with an embedded moisture-tracing module (Community Atmosphere Model version 3), forced by observed (1979-2013) sea-surface temperatures. The result suggests that about 40% of the moisture comes with the moisture flow associated with the seasonal migration of the Intertropical Convergence Zone (ITCZ) and originates from Guinea Coast, central Africa, and the Western Sahel. The Mediterranean Sea, Arabian Peninsula, and South Indian Ocean regions account for 10.2%, 8.1%, and 6.4%, respectively. Local evaporation and the rest of the globe supply the region with 20.3% and 13.2%, respectively. We also compared the result from this study to a previous analysis that used the Lagrangian model FLEXPART forced by ERA-Interim. The two approaches differ when comparing individual regions, but are in better agreement when neighboring regions of similar atmospheric flow features are grouped together. Interannual variability with the rainfall over the region is highly correlated with contributions from regions that are associated with the ITCZ movement, which is in turn linked to the Atlantic Multidecadal Oscillation. Our result is expected to provide insights for the effort on seasonal forecasting of the rainy season over Sahelian Sudan.

Measurements of atmospheric and gamma rays-balloon experiments at subantartic region

International Nuclear Information System (INIS)

Jayanthi, U.B.; Correa, R.V.; Blanco, F.G.

1986-01-01

The results of two stratospheric balloon experiments conducted to measure the atmospheric X and gamma rays are presented. These experiments, conducted at Comandante Ferraz base in subantarctic region, have provided the spectrum of ground radioactivity in gamma rays (0.2 to 2.9 MeV) and atmospheric X-ray spectra at different altitudes. We specifically chose to discuss the observed ceiling spectrum of X-rays in the 28 to 180KeV region observed at 7.0 g. cm -2 . We have utilized the data of other experiments with different telescope geometries, to evaluate the builup effects due to cosmic ray secondaries in atmosphere. This behaviour, previoulsy studied for atmospheric gamma rays, permitted to compare the up/down flux rations to explain the observed atmospheric X-ray spectrum. (Author) [pt

Regional Scale/Regional Climate Model Development and Its Applications at Goddard

Science.gov (United States)

Tao, W.-K.; Lau, W.; Qian, J.; Jia, Y.; Wetzel, P.; Chou, M.-D.; Wang, Y.; Lynn, B.

2000-01-01

A Regional Land-Atmosphere Climate Simulation System (RELACS) is being developed and implemented at NASA Goddard Space Flight Center. One of the major goals of RELACS is to use a regional scale model (Penn State/NCAR MM5) with improved physical processes and in particular land-related processes, to understand the role of the land surface and its interaction with convection and radiation as well as the water/energy cycles in the Indo-China/South China Sea (SCS)/China, N. America and S. America region.

Assessing uncertainty and sensitivity of model parameterizations and parameters in WRF affecting simulated surface fluxes and land-atmosphere coupling over the Amazon region

Science.gov (United States)

Qian, Y.; Wang, C.; Huang, M.; Berg, L. K.; Duan, Q.; Feng, Z.; Shrivastava, M. B.; Shin, H. H.; Hong, S. Y.

2016-12-01

This study aims to quantify the relative importance and uncertainties of different physical processes and parameters in affecting simulated surface fluxes and land-atmosphere coupling strength over the Amazon region. We used two-legged coupling metrics, which include both terrestrial (soil moisture to surface fluxes) and atmospheric (surface fluxes to atmospheric state or precipitation) legs, to diagnose the land-atmosphere interaction and coupling strength. Observations made using the Department of Energy's Atmospheric Radiation Measurement (ARM) Mobile Facility during the GoAmazon field campaign together with satellite and reanalysis data are used to evaluate model performance. To quantify the uncertainty in physical parameterizations, we performed a 120 member ensemble of simulations with the WRF model using a stratified experimental design including 6 cloud microphysics, 3 convection, 6 PBL and surface layer, and 3 land surface schemes. A multiple-way analysis of variance approach is used to quantitatively analyze the inter- and intra-group (scheme) means and variances. To quantify parameter sensitivity, we conducted an additional 256 WRF simulations in which an efficient sampling algorithm is used to explore the multiple-dimensional parameter space. Three uncertainty quantification approaches are applied for sensitivity analysis (SA) of multiple variables of interest to 20 selected parameters in YSU PBL and MM5 surface layer schemes. Results show consistent parameter sensitivity across different SA methods. We found that 5 out of 20 parameters contribute more than 90% total variance, and first-order effects dominate comparing to the interaction effects. Results of this uncertainty quantification study serve as guidance for better understanding the roles of different physical processes in land-atmosphere interactions, quantifying model uncertainties from various sources such as physical processes, parameters and structural errors, and providing insights for

Coupled atmosphere ocean climate model simulations in the Mediterranean region: effect of a high-resolution marine model on cyclones and precipitation

Directory of Open Access Journals (Sweden)

A. Sanna

2013-06-01

Full Text Available In this study we investigate the importance of an eddy-permitting Mediterranean Sea circulation model on the simulation of atmospheric cyclones and precipitation in a climate model. This is done by analyzing results of two fully coupled GCM (general circulation models simulations, differing only for the presence/absence of an interactive marine module, at very high-resolution (~ 1/16°, for the simulation of the 3-D circulation of the Mediterranean Sea. Cyclones are tracked by applying an objective Lagrangian algorithm to the MSLP (mean sea level pressure field. On annual basis, we find a statistically significant difference in vast cyclogenesis regions (northern Adriatic, Sirte Gulf, Aegean Sea and southern Turkey and in lifetime, giving evidence of the effect of both land–sea contrast and surface heat flux intensity and spatial distribution on cyclone characteristics. Moreover, annual mean convective precipitation changes significantly in the two model climatologies as a consequence of differences in both air–sea interaction strength and frequency of cyclogenesis in the two analyzed simulations.

ESA STSE Project “Sea Surface Temperature Diurnal Variability: Regional Extend – Implications in Atmospheric Modelling”

DEFF Research Database (Denmark)

Karagali, Ioanna

of the vertical extend of diurnal signals. Drifting buoys provide measurements close to the surface but are not always available. Moored buoys are generally not able to resolve the daily SST signal, which strongly weakens with depth within the upper water column. For such reasons, the General Ocean Turbulence......, atmospheric and oceanic modelling, bio-chemical processes and oceanic CO2 studies. The diurnal variability of SST, driven by the coincident occurrence of low enough wind and solar heating, is currently not properly understood. Atmospheric, oceanic and climate models are currently not adequately resolving...... the daily SST variability, resulting in biases of the total heat budget estimates and therefore, demised model accuracies. The ESA STSE funded project SSTDV:R.EX.-IM.A.M. aimed at characterising the regional extend of diurnal SST signals and their impact in atmospheric modelling. This study will briefly...

Regional Ocean Modeling System (ROMS): Main Hawaiian Islands: Data Assimilating

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Regional Ocean Modeling System (ROMS) 3-day, 3-hourly data assimilating hindcast for the region surrounding the main Hawaiian islands at approximately 4-km...

Modelling and tracer studies of atmospheric dispersion and deposition in regions of complex topography

International Nuclear Information System (INIS)

Norden, C.E.

1981-11-01

An indium tracer aerosol generating apparatus based on an alcohol/oxygen burner, and an analytical procedure by which filter samples containing tracer material could be analysed quantitatively by means of neutron activation analysis, were developed for use in atmospheric dispersion and deposition studies. A number of series of atmospheric dispersion experiments were conducted in the Richards Bay and Koeberg- Cape Town areas. The results are given, comparing the airbone tracer concentrations measured at ground level with values predicted by means of a numerical model, utilising two to three schemes, varying in sophistication, for calculating the dispersion coefficients. Recommendations are given regarding a dispersion model and dispersion coefficients for regular use in the Koeberg area, and ways for estimating plume trajectories

Modeling the atmospheric chemistry of TICs

Science.gov (United States)

Henley, Michael V.; Burns, Douglas S.; Chynwat, Veeradej; Moore, William; Plitz, Angela; Rottmann, Shawn; Hearn, John

2009-05-01

An atmospheric chemistry model that describes the behavior and disposition of environmentally hazardous compounds discharged into the atmosphere was coupled with the transport and diffusion model, SCIPUFF. The atmospheric chemistry model was developed by reducing a detailed atmospheric chemistry mechanism to a simple empirical effective degradation rate term (keff) that is a function of important meteorological parameters such as solar flux, temperature, and cloud cover. Empirically derived keff functions that describe the degradation of target toxic industrial chemicals (TICs) were derived by statistically analyzing data generated from the detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. To assess and identify areas to improve the developed atmospheric chemistry model, sensitivity and uncertainty analyses were performed to (1) quantify the sensitivity of the model output (TIC concentrations) with respect to changes in the input parameters and (2) improve, where necessary, the quality of the input data based on sensitivity results. The model predictions were evaluated against experimental data. Chamber data were used to remove the complexities of dispersion in the atmosphere.

The Swedish Regional Climate Modelling Programme, SWECLIM: a review.

Science.gov (United States)

Rummukainen, Markku; Bergström, Sten; Persson, Gunn; Rodhe, Johan; Tjernström, Michael

2004-06-01

The Swedish Regional Climate Modelling Programme, SWECLIM, was a 6.5-year national research network for regional climate modeling, regional climate change projections and hydrological impact assessment and information to a wide range of stakeholders. Most of the program activities focussed on the regional climate system of Northern Europe. This led to the establishment of an advanced, coupled atmosphere-ocean-hydrology regional climate model system, a suite of regional climate change projections and progress on relevant data and process studies. These were, in turn, used for information and educational purposes, as a starting point for impact analyses on different societal sectors and provided contributions also to international climate research.

Atmospheric sulfur and climate changes: a modelling study at mid and high-southern latitudes

International Nuclear Information System (INIS)

Castebrunet, H.

2007-09-01

The mid and high-southern latitudes are still marginally affected by anthropogenic sulfur emissions. They are the only regions in the world where the natural cycle of the atmospheric sulfur may still be observed. Sulfur aerosols are well-known for their radiative impact, and thus interact with climate. Climate can in turn affect atmospheric sulfur sources, distribution and chemistry. Antarctic ice cores provide information on the evolution of climate and sulfur deposition at the surface of the ice sheet at glacial-interglacial time scales. The aim of this thesis is to develop and use modeling towards a better understanding of the atmospheric sulfur cycle in antarctic and sub-antarctic regions. Ice core data are used to validate model results under glacial climate conditions. An Atmospheric General Circulation Model (AGCM) coupled to a sulfur chemistry module is used: the LMD-ZTSulfur model, version 4. An update of both the physical and chemical parts of the model. The model was first performed. The impact of there changes on modelled sulfur cycle are evaluated for modern climate. Further, boundary conditions are adapted to simulate the atmospheric circulation and sulfur cycle at the Last Glacial Maximum, approximately 20,000 years ago. In the model, sulfur is found to be highly sensitive to antarctic sea-ice coverage, which is still poorly known during the ice age. An original dataset of ice-age sea-ice coverage was developed. Its impact on the oceanic emissions of dimethyl sulfide, main precursor of sulfur aerosols at high-southern latitudes, is discussed. Using the same oceanic sulfur reservoirs as for present day climate, the model broadly reproduces the glacial deposits of sulfur aerosols on the Antarctic plateau, suggesting little impact of climate on oceanic sulfur production in the Antarctic region. Sensitivity tests were carried out to draw an up-to-date status of major uncertainties and difficulties facing future progress in understanding atmospheric

Climatic features of the Red Sea from a regional assimilative model

KAUST Repository

Viswanadhapalli, Yesubabu

2016-08-16

The Advanced Research version of Weather Research and Forecasting (WRF-ARW) model was used to generate a downscaled, 10-km resolution regional climate dataset over the Red Sea and adjacent region. The model simulations are performed based on two, two-way nested domains of 30- and 10-km resolutions assimilating all conventional observations using a cyclic three-dimensional variational approach over an initial 12-h period. The improved initial conditions are then used to generate regional climate products for the following 24 h. We combined the resulting daily 24-h datasets to construct a 15-year Red Sea atmospheric downscaled product from 2000 to 2014. This 15-year downscaled dataset is evaluated via comparisons with various in situ and gridded datasets. Our analysis indicates that the assimilated model successfully reproduced the spatial and temporal variability of temperature, wind, rainfall, relative humidity and sea level pressure over the Red Sea region. The model also efficiently simulated the seasonal and monthly variability of wind patterns, the Red Sea Convergence Zone and associated rainfall. Our results suggest that dynamical downscaling and assimilation of available observations improve the representation of regional atmospheric features over the Red Sea compared to global analysis data from the National Centers for Environmental Prediction. We use the dataset to describe the atmospheric climatic conditions over the Red Sea region. © 2016 Royal Meteorological Society.

Ecosystem feedbacks to climate change in California: Development, testing, and analysis using a coupled regional atmosphere and land-surface model (WRF3-CLM3.5)

Energy Technology Data Exchange (ETDEWEB)

Subin, Z.M.; Riley, W.J.; Kueppers, L.M.; Jin, J.; Christianson, D.S.; Torn, M.S.

2010-11-01

A regional atmosphere model [Weather Research and Forecasting model version 3 (WRF3)] and a land surface model [Community Land Model, version 3.5 (CLM3.5)] were coupled to study the interactions between the atmosphere and possible future California land-cover changes. The impact was evaluated on California's climate of changes in natural vegetation under climate change and of intentional afforestation. The ability of WRF3 to simulate California's climate was assessed by comparing simulations by WRF3-CLM3.5 and WRF3-Noah to observations from 1982 to 1991. Using WRF3-CLM3.5, the authors performed six 13-yr experiments using historical and future large-scale climate boundary conditions from the Geophysical Fluid Dynamics Laboratory Climate Model version 2.1 (GFDL CM2.1). The land-cover scenarios included historical and future natural vegetation from the Mapped Atmosphere-Plant-Soil System-Century 1 (MC1) dynamic vegetation model, in addition to a future 8-million-ha California afforestation scenario. Natural vegetation changes alone caused summer daily-mean 2-m air temperature changes of -0.7 to +1 C in regions without persistent snow cover, depending on the location and the type of vegetation change. Vegetation temperature changes were much larger than the 2-m air temperature changes because of the finescale spatial heterogeneity of the imposed vegetation change. Up to 30% of the magnitude of the summer daily-mean 2-m air temperature increase and 70% of the magnitude of the 1600 local time (LT) vegetation temperature increase projected under future climate change were attributable to the climate-driven shift in land cover. The authors projected that afforestation could cause local 0.2-1.2 C reductions in summer daily-mean 2-m air temperature and 2.0-3.7 C reductions in 1600 LT vegetation temperature for snow-free regions, primarily because of increased evapotranspiration. Because some of these temperature changes are of comparable magnitude to those

A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations

Science.gov (United States)

Rummukainen, M.; Räisänen, J.; Bringfelt, B.; Ullerstig, A.; Omstedt, A.; Willén, U.; Hansson, U.; Jones, C.

This work presents a regional climate model, the Rossby Centre regional Atmospheric model (RCA1), recently developed from the High Resolution Limited Area Model (HIRLAM). The changes in the HIRLAM parametrizations, necessary for climate-length integrations, are described. A regional Baltic Sea ocean model and a modeling system for the Nordic inland lake systems have been coupled with RCA1. The coupled system has been used to downscale 10-year time slices from two different general circulation model (GCM) simulations to provide high-resolution regional interpretation of large-scale modeling. A selection of the results from the control runs, i.e. the present-day climate simulations, are presented: large-scale free atmospheric fields, the surface temperature and precipitation results and results for the on-line simulated regional ocean and lake surface climates. The regional model modifies the surface climate description compared to the GCM simulations, but it is also substantially affected by the biases in the GCM simulations. The regional model also improves the representation of the regional ocean and the inland lakes, compared to the GCM results.

A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations

Energy Technology Data Exchange (ETDEWEB)

Rummukainen, M.; Raeisaenen, J.; Bringfelt, B.; Ullerstig, A.; Omstedt, A.; Willen, U.; Hansson, U.; Jones, C. [Rossby Centre, Swedish Meteorological and Hydrological Inst., Norrkoeping (Sweden)

2001-03-01

This work presents a regional climate model, the Rossby Centre regional Atmospheric model (RCA1), recently developed from the High Resolution Limited Area Model (HIRLAM). The changes in the HIRLAM parametrizations, necessary for climate-length integrations, are described. A regional Baltic Sea ocean model and a modeling system for the Nordic inland lake systems have been coupled with RCA1. The coupled system has been used to downscale 10-year time slices from two different general circulation model (GCM) simulations to provide high-resolution regional interpretation of large-scale modeling. A selection of the results from the control runs, i.e. the present-day climate simulations, are presented: large-scale free atmospheric fields, the surface temperature and precipitation results and results for the on-line simulated regional ocean and lake surface climates. The regional model modifies the surface climate description compared to the GCM simulations, but it is also substantially affected by the biases in the GCM simulations. The regional model also improves the representation of the regional ocean and the inland lakes, compared to the GCM results. (orig.)

Refining multi-model projections of temperature extremes by evaluation against land–atmosphere coupling diagnostics

Directory of Open Access Journals (Sweden)

S. Sippel

2017-05-01

Full Text Available The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land–atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land–atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T and evapotranspiration (ET benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land–atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5 archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T–ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T–ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand

Ensemble atmospheric dispersion modeling for emergency response consequence assessments

International Nuclear Information System (INIS)

Addis, R.P.; Buckley, R.L.

2003-01-01

models. This provides a better understanding of the atmosphere and plume behavior than would a single model output. Atmospheric models often give the impression of greater accuracy than the science is capable of delivering. The ensemble approach is a powerful way to reassert the concept of having a family of equally valid solutions, while enabling outliers to be identified. The U.S. Department of Energy's Savannah River Technology Center (SRTC) has participated in RTMOD and ENSEMBLE. SRTC uses the Regional Atmospheric Modeling System (RAMS) and Lagrangian Particle Dispersion Model (LPDM) to provide plume forecasts in real-time for the European grid as described in the figure. The NOAA northern hemispheric model, Global Forecast System (a combination of the medium range forecast and aviation forecast models), is used to provide the initial and boundary conditions for RAMS. The model plume forecast data are sent to the ENSEMBLE WEB page in real-time where they may be compared with other model outputs. SRTC has participated in all the ENSEMBLE exercises in real-time. An example of the ensemble output is shown in the figure, which shows an overlay of the SRTC (crosshatched) initial 60-hour forecast for the plume overlaid on an ensemble of 5 other model outputs. The plume shadings show the level of consensus for a minimum threshold, enabling modelers to determine consensus between models and identify possible outliers. The traditional approach to provide atmospheric consequence assessment tools to aid decision-makers in response to a release from a nuclear facility is to provide a plume output from a particular model. However, the non-unique nature of solutions to the non-linear equations that govern the atmosphere, and the sensitivity of such equations to perturbations in the initial and boundary conditions, results in any single model output being simply one of many viable solutions. As such, the traditional approach does a disservice to decision-makers by inferring greater

Soil-vegetation-atmosphere transfer modeling

Energy Technology Data Exchange (ETDEWEB)

Ikonen, J P; Sucksdorff, Y [Finnish Environment Agency, Helsinki (Finland)

1997-12-31

In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

Soil-vegetation-atmosphere transfer modeling

Energy Technology Data Exchange (ETDEWEB)

Ikonen, J.P.; Sucksdorff, Y. [Finnish Environment Agency, Helsinki (Finland)

1996-12-31

In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

Evaluating Land-Atmosphere Moisture Feedbacks in Earth System Models With Spaceborne Observations

Science.gov (United States)

Levine, P. A.; Randerson, J. T.; Lawrence, D. M.; Swenson, S. C.

2016-12-01

We have developed a set of metrics for measuring the feedback loop between the land surface moisture state and the atmosphere globally on an interannual time scale. These metrics consider both the forcing of terrestrial water storage (TWS) on subsequent atmospheric conditions as well as the response of TWS to antecedent atmospheric conditions. We designed our metrics to take advantage of more than one decade's worth of satellite observations of TWS from the Gravity Recovery and Climate Experiment (GRACE) along with atmospheric variables from the Atmospheric Infrared Sounder (AIRS), the Global Precipitation Climatology Project (GPCP), and Clouds and the Earths Radiant Energy System (CERES). Metrics derived from spaceborne observations were used to evaluate the strength of the feedback loop in the Community Earth System Model (CESM) Large Ensemble (LENS) and in several models that contributed simulations to Phase 5 of the Coupled Model Intercomparison Project (CMIP5). We found that both forcing and response limbs of the feedback loop were generally stronger in tropical and temperate regions in CMIP5 models and even more so in LENS compared to satellite observations. Our analysis suggests that models may overestimate the strength of the feedbacks between the land surface and the atmosphere, which is consistent with previous studies conducted across different spatial and temporal scales.

Mean atmospheric temperature model estimation for GNSS meteorology using AIRS and AMSU data

Directory of Open Access Journals (Sweden)

Rata Suwantong

2017-03-01

Full Text Available In this paper, the problem of modeling the relationship between the mean atmospheric and air surface temperatures is addressed. Particularly, the major goal is to estimate the model parameters at a regional scale in Thailand. To formulate the relationship between the mean atmospheric and air surface temperatures, a triply modulated cosine function was adopted to model the surface temperature as a periodic function. The surface temperature was then converted to mean atmospheric temperature using a linear function. The parameters of the model were estimated using an extended Kalman filter. Traditionally, radiosonde data is used. In this paper, satellite data from an atmospheric infrared sounder, and advanced microwave sounding unit sensors was used because it is open source data and has global coverage with high temporal resolution. The performance of the proposed model was tested against that of a global model via an accuracy assessment of the computed GNSS-derived PWV.

The thermal structure of Triton's atmosphere - Pre-Voyager models

Science.gov (United States)

Mckay, Christopher P.; Pollack, James B.; Zent, Aaron P.; Cruikshank, Dale P.; Courtin, Regis

1989-01-01

Spectral data from earth observations have indicated the presence of N2 and CH4 on Triton. This paper outlines the use of the 1-D radiative-convective model developed for Titan to calculate the current pressure of N2 and CH4 on Triton. The production of haze material is obtained by scaling down from the Titan value. Results and predictions for the Voyager Triton encounter are as follows: A N2-CH4 atmosphere on Triton is thermodynamically self consistent and would have a surface pressure of approximately 50 millibar; due to the chemically produced haze, Triton has a hot atmosphere with a temperature of approximately 130 K; Triton's troposphere is a region of saturation of the major constituent of the atmosphere, N2.

Preliminary results from the ESA STSE project on SST diurnal variability, its regional extent and implications in atmospheric modelling (SSTDV:R.EX.–IM.A.M.)

DEFF Research Database (Denmark)

Karagali, Ioanna; Hasager, Charlotte Bay; Høyer, Jacob L.

2013-01-01

This study presents some preliminary results of the ESA Support To Science Element (STSE) funded project on the Diurnal Variability of the Sea Surface Temperature, regarding its Regional Extend and Implications in Atmospheric Modelling (SSTDV:R.EX.–IM.A.M.). Comparisons of SEVIRI SST with AATSR...

Improved Meteorological Input for Atmospheric Release Decision support Systems and an Integrated LES Modeling System for Atmospheric Dispersion of Toxic Agents: Homeland Security Applications

Energy Technology Data Exchange (ETDEWEB)

Arnold, E; Simpson, M; Larsen, S; Gash, J; Aluzzi, F; Lundquist, J; Sugiyama, G

2010-04-26

When hazardous material is accidently or intentionally released into the atmosphere, emergency response organizations look to decision support systems (DSSs) to translate contaminant information provided by atmospheric models into effective decisions to protect the public and emergency responders and to mitigate subsequent consequences. The Department of Homeland Security (DHS)-led Interagency Modeling and Atmospheric Assessment Center (IMAAC) is one of the primary DSSs utilized by emergency management organizations. IMAAC is responsible for providing 'a single piont for the coordination and dissemination of Federal dispersion modeling and hazard prediction products that represent the Federal position' during actual or potential incidents under the National Response Plan. The Department of Energy's (DOE) National Atmospheric Release Advisory Center (NARAC), locatec at the Lawrence Livermore National Laboratory (LLNL), serves as the primary operations center of the IMAAC. A key component of atmospheric release decision support systems is meteorological information - models and data of winds, turbulence, and other atmospheric boundary-layer parameters. The accuracy of contaminant predictions is strongly dependent on the quality of this information. Therefore, the effectiveness of DSSs can be enhanced by improving the meteorological options available to drive atmospheric transport and fate models. The overall goal of this project was to develop and evaluate new meteorological modeling capabilities for DSSs based on the use of NASA Earth-science data sets in order to enhance the atmospheric-hazard information provided to emergency managers and responders. The final report describes the LLNL contributions to this multi-institutional effort. LLNL developed an approach to utilize NCAR meteorological predictions using NASA MODIS data for the New York City (NYC) region and demonstrated the potential impact of the use of different data sources and data

The effect of regional-scale soil-moisture deficits on mesoscale atmospheric dynamics that influence fire severity

Energy Technology Data Exchange (ETDEWEB)

Fast, J.D.

1994-09-30

This study employs a three-dimensional, nonhydrostatic mesoscale model to evaluate the effects of horizontally heterogeneous soil moisture and vegetation type on the atmosphere during two periods in which wildland fires occurred. Numerical sensitivity simulations demonstrate that evapotranspiration significantly affects the boundary-layer structure embedded in the synoptic-scale circulations. In regions with sufficiently moist soils, evapotranspiration increases the humidity and modifies the diurnally varying temperature near the surface. Occasionally, changes in the humidity and temperature fields can also be seen a significant distance downwind of the moist soil regions. The perturbations in the temperature fields ultimately affect the wind speed and direction over or at the boundaries of the moist-soil regions, but only at certain times during the simulation period. The higher humidity also increases the cloudiness and changes the precipitation amounts, indicating that soil moisture and vegetation may play an important role in modifying the spatial distribution and intensity of precipitation. A lower atmospheric stability index, that is an indicator of the potential for wildland fire, is also calculated from the model results. This index is also sensitive to the horizontal distribution of soil moisture and vegetation, especially in regions with relatively moist soils. While only two periods are examined in this study, the impact of surface inhomogeneities in soil moisture and vegetation type on the atmosphere is expected to be highly dependent on the particular synoptic conditions and upon the distribution of soil moisture.

Modeling the influence of atmospheric leading modes on the variability of the Arctic freshwater cycle

Science.gov (United States)

Niederdrenk, L.; Sein, D.; Mikolajewicz, U.

2013-12-01

Global general circulation models show remarkable differences in modeling the Arctic freshwater cycle. While they agree on the general sinks and sources of the freshwater budget, they differ largely in the magnitude of the mean values as well as in the variability of the freshwater terms. Regional models can better resolve the complex topography and small scale processes, but they are often uncoupled, thus missing the air-sea interaction. Additionally, regional models mostly use some kind of salinity restoring or flux correction, thus disturbing the freshwater budget. Our approach to investigate the Arctic hydrologic cycle and its variability is a regional atmosphere-ocean model setup, consisting of the global ocean model MPIOM with high resolution in the Arctic coupled to the regional atmosphere model REMO. The domain of the atmosphere model covers all catchment areas of the rivers draining into the Arctic. To account for all sinks and sources of freshwater in the Arctic, we include a discharge model providing terrestrial lateral waterflows. We run the model without salinity restoring but with freshwater correction, which is set to zero in the Arctic. This allows for the analysis of a closed freshwater budget in the Artic region. We perform experiments for the second half of the 20th century and use data from the global model MPIOM/ECHAM5 performed with historical conditions, that was used within the 4th Assessment Report of the IPCC, as forcing for our regional model. With this setup, we investigate how the dominant modes of large-scale atmospheric variability impact the variability in the freshwater components. We focus on the two leading empirical orthogonal functions of winter mean sea level pressure, as well as on the North Atlantic Oscillation and the Siberian High. These modes have a large impact on the Arctic Ocean circulation as well as on the solid and liquid export through Fram Strait and through the Canadian archipelago. However, they cannot explain

Intercomparison of the seasonal cycle of tropical surface stress in 17 AMIP atmospheric general circulation models

Energy Technology Data Exchange (ETDEWEB)

Saji, N.H.; Goswami, B.N. [Indian Inst. of Sci., Bangalore (India). Centre for Atmos. and Oceanic Sci.

1997-08-01

The mean state of the tropical atmosphere is important as the nature of the coupling between the ocean and the atmosphere depends nonlinearly on the basic state of the coupled system. The simulation of the annual cycle of the tropical surface wind stress by 17 atmospheric general circulation models (AGCMs) is examined and intercompared. The models considered were part of the atmospheric model intercomparison project (AMIP) and were integrated with observed sea surface temperature (SST) for the decade 1979-1988. Several measures have been devised to intercompare the performance of the 17 models on global tropical as well as regional scales. Within the limits of observational uncertainties, the models under examination simulate realistic tropical area-averaged zonal and meridional annual mean stresses. This is a noteworthy improvement over older generation low resolution models which were noted for their simulation of surface stresses considerably weaker than the observations. The models also simulate realistic magnitudes of the spatial distribution of the annual mean surface stress field and are seen to reproduce realistically its observed spatial pattern. Similar features are observed in the simulations of the annual variance field. The models perform well over almost all the tropical regions apart from a few. Of these, the simulations over Somali are interesting. Over this region, the models are seen to underestimate the annual mean zonal and meridional stresses. There is also wide variance between the different models in simulating these quantities. 44 refs.

Spectra calculations in central and wing regions of CO2 IR bands between 10 and 20 μm. III: atmospheric emission spectra

International Nuclear Information System (INIS)

Niro, F.; Clarmann, T. von; Jucks, K.; Hartmann, J.-M.

2005-01-01

A theoretical model for the prediction of CO 2 absorption in both central and wing regions of infrared absorption bands was presented in the companion paper I. It correctly accounts for line-mixing effects and was validated by comparisons with laboratory spectra in the 600-1000 cm -1 region. This quality was confirmed using atmospheric transmissions measured by solar occultation experiments in the second paper. The present work completes these studies by now considering atmospheric emission in the 10-20 μm range. Comparisons are made between computed atmospheric radiances and measurements obtained using four different Fourier transform experiments collecting spectra for nadir, up-looking, as well as limb (from balloon and satellite) geometries. Our results confirm that using a Voigt model can lead to very large errors that affect the spectrum more than 300 cm -1 away from the center of the CO 2 ν 2 band. They also demonstrate the capability of our model to represent accurately the radiances in the entire region for a variety of atmospheric paths. This success opens interesting perspectives for the sounding of pressure and temperature profiles, particularly at low altitudes. Another benefit of the quality of the model should be an increased accuracy in the retrieval of atmospheric state parameters from broad features in the measured spectra (clouds, aerosols, heavy trace gases)

Contribution of lateral terrestrial water flows to the regional hydrological cycle: A joint soil-atmospheric moisture tagging procedure with WRF-Hydro

Science.gov (United States)

Arnault, Joel; Wei, Jianhui; Zhang, Zhenyu; Wagner, Sven; Kunstmann, Harald

2017-04-01

Water resources management requires an accurate knowledge of the behavior of the regional hydrological cycle components, including precipitation, evapotranspiration, river discharge and soil water storage. Atmospheric models such as the Weather Research and Forecasting (WRF) model provide a tool to evaluate these components. The main drawback of these atmospheric models, however, is that the terrestrial segment of the hydrological cycle is reduced to vertical infiltration, and that lateral terrestrial water flows are neglected. Recent model developments have focused on coupled atmospheric-hydrological modeling systems, such as WRF-hydro, in order to take into account subsurface, overland and river flow. The aim of this study is to investigate the contribution of lateral terrestrial water flows to the regional hydrological cycle, with the help of a joint soil-atmospheric moisture tagging procedure. This procedure is the extended version of an existing atmospheric moisture tagging method developed in WRF and WRF-Hydro (Arnault et al. 2017). It is used to quantify the partitioning of precipitation into water stored in the soil, runoff, evapotranspiration, and potentially subsequent precipitation through regional recycling. An application to a high precipitation event on 23 June 2009 in the upper Danube river basin, Germany and Austria, is presented. Precipitating water during this day is tagged for the period 2009-2011. Its contribution to runoff and evapotranspiration decreases with time, but is still not negligible in the summer 2011. At the end of the study period, less than 5 % of the precipitating water on 23 June 2009 remains in the soil. The additionally resolved lateral terrestrial water flows in WRF-Hydro modify the partitioning between surface and underground runoff, in association with a slight increase of evapotranspiration and recycled precipitation. Reference: Arnault, J., R. Knoche, J. Wei, and H. Kunstmann (2016), Evaporation tagging and atmospheric

Description and Evaluation of IAP-AACM: A Global-regional Aerosol Chemistry Model for the Earth System Model CAS-ESM

Science.gov (United States)

Wei, Y.; Chen, X.

2017-12-01

We present a first description and evaluation of the IAP Atmospheric Aerosol Chemistry Model (IAP-AACM) which has been integrated into the earth system model CAS-ESM. In this way it is possible to research into interaction of clouds and aerosol by its two-way coupling with the IAP Atmospheric General Circulation Model (IAP-AGCM). The model has a nested global-regional grid based on the Global Environmental Atmospheric Transport Model (GEATM) and the Nested Air Quality Prediction Modeling System (NAQPMS). The AACM provides two optional gas chemistry schemes, the CBM-Z gas chemistry as well as a sulfur oxidize box designed specifically for the CAS-ESM. Now the model driven by AGCM has been applied to a 1-year simulation of tropospheric chemistry both on global and regional scales for 2014, and been evaluated against various observation datasets, including aerosol precursor gas concentration, aerosol mass and number concentrations. Furthermore, global budgets in AACM are compared with other global aerosol models. Generally, the AACM simulations are within the range of other global aerosol model predictions, and the model has a reasonable agreement with observations of gases and particles concentration both on global and regional scales.

Spectral model for clear sky atmospheric longwave radiation

Science.gov (United States)

Li, Mengying; Liao, Zhouyi; Coimbra, Carlos F. M.

2018-04-01

An efficient spectrally resolved radiative model is used to calculate surface downwelling longwave (DLW) radiation (0 ∼ 2500 cm-1) under clear sky (cloud free) conditions at the ground level. The wavenumber spectral resolution of the model is 0.01 cm-1 and the atmosphere is represented by 18 non-uniform plane-parallel layers with pressure in each layer determined on a pressure-based coordinate system. The model utilizes the most up-to-date (2016) HITRAN molecular spectral data for 7 atmospheric gases: H2O, CO2, O3, CH4, N2O, O2 and N2. The MT_CKD model is used to calculate water vapor and CO2 continuum absorption coefficients. Longwave absorption and scattering coefficients for aerosols are modeled using Mie theory. For the non-scattering atmosphere (aerosol free), the surface DLW agrees within 2.91% with mean values from the InterComparison of Radiation Codes in Climate Models (ICRCCM) program, with spectral deviations below 0.035 W cm m-2. For a scattering atmosphere with typical aerosol loading, the DLW calculated by the proposed model agrees within 3.08% relative error when compared to measured values at 7 climatologically diverse SURFRAD stations. This relative error is smaller than a calibrated parametric model regressed from data for those same 7 stations, and within the uncertainty (+/- 5 W m-2) of pyrgeometers commonly used for meteorological and climatological applications. The DLW increases by 1.86 ∼ 6.57 W m-2 when compared with aerosol-free conditions, and this increment decreases with increased water vapor content due to overlap with water vapor bands. As expected, the water vapor content at the layers closest to the surface contributes the most to the surface DLW, especially in the spectral region 0 ∼ 700 cm-1. Additional water vapor content (mostly from the lowest 1 km of the atmosphere) contributes to the spectral range of 400 ∼ 650 cm-1. Low altitude aerosols ( ∼ 3.46 km or less) contribute to the surface value of DLW mostly in the

1D Atmosphere Models from Inversion of Fe i 630 nm Observations with an Application to Solar Irradiance Studies

Energy Technology Data Exchange (ETDEWEB)

Cristaldi, Alice; Ermolli, Ilaria, E-mail: alice.cristaldi@oaroma.inaf.it [INAF Osservatorio Astronomico di Roma, via Frascati 33, Monte Porzio Catone, I-00078 (Italy)

2017-06-01

Present-day semi-empirical models of solar irradiance (SI) variations reconstruct SI changes measured on timescales greater than a day by using spectra computed in one dimensional atmosphere models (1D models), which are representative of various solar surface features. Various recent studies have pointed out, however, that the spectra synthesized in 1D models do not reflect the radiative emission of the inhomogenous atmosphere revealed by high-resolution solar observations. We aimed to derive observation-based atmospheres from such observations and test their accuracy for SI estimates. We analyzed spectropolarimetric data of the Fe i 630 nm line pair in photospheric regions that are representative of the granular quiet-Sun pattern (QS) and of small- and large-scale magnetic features, both bright and dark with respect to the QS. The data were taken on 2011 August 6, with the CRisp Imaging Spectropolarimeter at the Swedish Solar Telescope, under excellent seeing conditions. We derived atmosphere models of the observed regions from data inversion with the SIR code. We studied the sensitivity of results to spatial resolution and temporal evolution, and discuss the obtained atmospheres with respect to several 1D models. The atmospheres derived from our study agree well with most of the 1D models we compare our results with, both qualitatively and quantitatively (within 10%), except for pore regions. Spectral synthesis computations of the atmosphere obtained from the QS observations return an SI between 400 and 2400 nm that agrees, on average, within 2.2% with standard reference measurements, and within −0.14% with the SI computed on the QS atmosphere employed by the most advanced semi-empirical model of SI variations.

Regional Atmospheric CO2 Inversion Reveals Seasonal and Geographic Differences in Amazon Net Biome Exchange

Science.gov (United States)

Alden, Caroline B.; Miller, John B.; Gatti, Luciana V.; Gloor, Manuel M.; Guan, Kaiyu; Michalak, Anna M.; van der Laan-Luijkx, Ingrid; Touma, Danielle; Andrews, Arlyn; Basso, Luana G.;

Local-scale high-resolution atmospheric dispersion model using large-eddy simulation. LOHDIM-LES

International Nuclear Information System (INIS)

Nakayama, Hiromasa; Nagai, Haruyasu

2016-03-01

We developed LOcal-scale High-resolution atmospheric DIspersion Model using Large-Eddy Simulation (LOHDIM-LES). This dispersion model is designed based on LES which is effective to reproduce unsteady behaviors of turbulent flows and plume dispersion. The basic equations are the continuity equation, the Navier-Stokes equation, and the scalar conservation equation. Buildings and local terrain variability are resolved by high-resolution grids with a few meters and these turbulent effects are represented by immersed boundary method. In simulating atmospheric turbulence, boundary layer flows are generated by a recycling turbulent inflow technique in a driver region set up at the upstream of the main analysis region. This turbulent inflow data are imposed at the inlet of the main analysis region. By this approach, the LOHDIM-LES can provide detailed information on wind velocities and plume concentration in the investigated area. (author)

Numberical Calculations of Atmospheric Conditions over Tibetan Plateau by Using WRF Model

International Nuclear Information System (INIS)

Qian, Xuan; Yao, Yongqiang; Wang, Hongshuai; Liu, Liyong; Li, Junrong; Yin, Jia

2015-01-01

The wind field, precipitable water vapor are analyzed by using the mesoscale numerical model WRF over Tibetan Plateau, and the aerosol is analyzed by using WRF- CHEM model. The spatial and vertical distributions of the relevant atmospheric factors are summarized, providing truth evidence for selecting and further evaluating an astronomical site. It has been showed that this method could provide good evaluation of atmospheric conditions. This study serves as a further demonstration towards astro-climate regionalization, and provides with essential database for astronomical site survey over Tibetan Plateau. (paper)

Toward a Unified Representation of Atmospheric Convection in Variable-Resolution Climate Models

Energy Technology Data Exchange (ETDEWEB)

Walko, Robert [Univ. of Miami, Coral Gables, FL (United States)

2016-11-07

The purpose of this project was to improve the representation of convection in atmospheric weather and climate models that employ computational grids with spatially-variable resolution. Specifically, our work targeted models whose grids are fine enough over selected regions that convection is resolved explicitly, while over other regions the grid is coarser and convection is represented as a subgrid-scale process. The working criterion for a successful scheme for representing convection over this range of grid resolution was that identical convective environments must produce very similar convective responses (i.e., the same precipitation amount, rate, and timing, and the same modification of the atmospheric profile) regardless of grid scale. The need for such a convective scheme has increased in recent years as more global weather and climate models have adopted variable resolution meshes that are often extended into the range of resolving convection in selected locations.

Dust measurement campaign in the Mantes region atmosphere; Campagne de mesures ``poussieres`` dans l`atmosphere de la region Mantaise

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-12-31

A measurement campaign have been carried out in the Mantes region (West of Paris) in order to determine particulate concentrations and types in the city atmosphere: granulometric particulate concentrations and concentration levels of the various types of airborne particulates (metals and metalloids, black smoke, polycyclic aromatic hydrocarbons, mono-cyclic aromatic hydrocarbons) are presented. The wind direction and speed have been taken into consideration

Advances in understanding, models and parameterizations of biosphere-atmosphere ammonia exchange

Science.gov (United States)

Flechard, C. R.; Massad, R.-S.; Loubet, B.; Personne, E.; Simpson, D.; Bash, J. O.; Cooter, E. J.; Nemitz, E.; Sutton, M. A.

2013-07-01

Atmospheric ammonia (NH3) dominates global emissions of total reactive nitrogen (Nr), while emissions from agricultural production systems contribute about two-thirds of global NH3 emissions; the remaining third emanates from oceans, natural vegetation, humans, wild animals and biomass burning. On land, NH3 emitted from the various sources eventually returns to the biosphere by dry deposition to sink areas, predominantly semi-natural vegetation, and by wet and dry deposition as ammonium (NH4+) to all surfaces. However, the land/atmosphere exchange of gaseous NH3 is in fact bi-directional over unfertilized as well as fertilized ecosystems, with periods and areas of emission and deposition alternating in time (diurnal, seasonal) and space (patchwork landscapes). The exchange is controlled by a range of environmental factors, including meteorology, surface layer turbulence, thermodynamics, air and surface heterogeneous-phase chemistry, canopy geometry, plant development stage, leaf age, organic matter decomposition, soil microbial turnover, and, in agricultural systems, by fertilizer application rate, fertilizer type, soil type, crop type, and agricultural management practices. We review the range of processes controlling NH3 emission and uptake in the different parts of the soil-canopy-atmosphere continuum, with NH3 emission potentials defined at the substrate and leaf levels by different [NH4+] / [H+] ratios (Γ). Surface/atmosphere exchange models for NH3 are necessary to compute the temporal and spatial patterns of emissions and deposition at the soil, plant, field, landscape, regional and global scales, in order to assess the multiple environmental impacts of airborne and deposited NH3 and NH4+. Models of soil/vegetation/atmosphere NH3 exchange are reviewed from the substrate and leaf scales to the global scale. They range from simple steady-state, "big leaf" canopy resistance models, to dynamic, multi-layer, multi-process, multi-chemical species schemes

Advances in understanding, models and parameterizations of biosphere-atmosphere ammonia exchange

Directory of Open Access Journals (Sweden)

C. R. Flechard

2013-07-01

Full Text Available Atmospheric ammonia (NH3 dominates global emissions of total reactive nitrogen (Nr, while emissions from agricultural production systems contribute about two-thirds of global NH3 emissions; the remaining third emanates from oceans, natural vegetation, humans, wild animals and biomass burning. On land, NH3 emitted from the various sources eventually returns to the biosphere by dry deposition to sink areas, predominantly semi-natural vegetation, and by wet and dry deposition as ammonium (NH4+ to all surfaces. However, the land/atmosphere exchange of gaseous NH3 is in fact bi-directional over unfertilized as well as fertilized ecosystems, with periods and areas of emission and deposition alternating in time (diurnal, seasonal and space (patchwork landscapes. The exchange is controlled by a range of environmental factors, including meteorology, surface layer turbulence, thermodynamics, air and surface heterogeneous-phase chemistry, canopy geometry, plant development stage, leaf age, organic matter decomposition, soil microbial turnover, and, in agricultural systems, by fertilizer application rate, fertilizer type, soil type, crop type, and agricultural management practices. We review the range of processes controlling NH3 emission and uptake in the different parts of the soil-canopy-atmosphere continuum, with NH3 emission potentials defined at the substrate and leaf levels by different [NH4+] / [H+] ratios (Γ. Surface/atmosphere exchange models for NH3 are necessary to compute the temporal and spatial patterns of emissions and deposition at the soil, plant, field, landscape, regional and global scales, in order to assess the multiple environmental impacts of airborne and deposited NH3 and NH4+. Models of soil/vegetation/atmosphere NH3 exchange are reviewed from the substrate and leaf scales to the global scale. They range from simple steady-state, "big leaf" canopy resistance models, to dynamic, multi-layer, multi-process, multi

Pluto's atmosphere

International Nuclear Information System (INIS)

Elliot, J.L.; Dunham, E.W.; Bosh, A.S.; Slivan, S.M.; Young, L.A.

1989-01-01

Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references

Multi-year Estimates of Methane Fluxes in Alaska from an Atmospheric Inverse Model

Science.gov (United States)

Miller, S. M.; Commane, R.; Chang, R. Y. W.; Miller, C. E.; Michalak, A. M.; Dinardo, S. J.; Dlugokencky, E. J.; Hartery, S.; Karion, A.; Lindaas, J.; Sweeney, C.; Wofsy, S. C.

2015-12-01

We estimate methane fluxes across Alaska over a multi-year period using observations from a three-year aircraft campaign, the Carbon Arctic Reservoirs Vulnerability Experiment (CARVE). Existing estimates of methane from Alaska and other Arctic regions disagree in both magnitude and distribution, and before the CARVE campaign, atmospheric observations in the region were sparse. We combine these observations with an atmospheric particle trajectory model and a geostatistical inversion to estimate surface fluxes at the model grid scale. We first use this framework to estimate the spatial distribution of methane fluxes across the state. We find the largest fluxes in the south-east and North Slope regions of Alaska. This distribution is consistent with several estimates of wetland extent but contrasts with the distribution in most existing flux models. These flux models concentrate methane in warmer or more southerly regions of Alaska compared to the estimate presented here. This result suggests a discrepancy in how existing bottom-up models translate wetland area into methane fluxes across the state. We next use the inversion framework to explore inter-annual variability in regional-scale methane fluxes for 2012-2014. We examine the extent to which this variability correlates with weather or other environmental conditions. These results indicate the possible sensitivity of wetland fluxes to near-term variability in climate.

An Overview of Modeling Middle Atmospheric Odd Nitrogen

Science.gov (United States)

Jackman, Charles H.; Kawa, S. Randolph; Einaudi, Franco (Technical Monitor)

2001-01-01

Odd nitrogen (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, and BrONO2) constituents are important components in the control of middle atmospheric ozone. Several processes lead to the production of odd nitrogen (NO(sub y)) in the middle atmosphere (stratosphere and mesosphere) including the oxidation of nitrous oxide (N2O), lightning, downflux from the thermosphere, and energetic charged particles (e.g., galactic cosmic rays, solar proton events, and energetic electron precipitation). The dominant production mechanism of NO(sub y) in the stratosphere is N2O oxidation, although other processes contribute. Mesospheric NO(sub y) is influenced by N2O oxidation, downflux from the thermosphere, and energetic charged particles. NO(sub y) is destroyed in the middle atmosphere primarily via two processes: 1) dissociation of NO to form N and O followed by N + NO yielding N2 + O to reform even nitrogen; and 2) transport to the troposphere where HNO3 can be rapidly scavenged in water droplets and rained out of the atmosphere. There are fairly significant differences among global models that predict NO(sub y). NO(sub y) has a fairly long lifetime in the stratosphere (months to years), thus disparate transport in the models probably contributes to many of these differences. Satellite and aircraft measurement provide modeling tests of the various components of NO(sub y). Although some recent reaction rate measurements have led to improvements in model/measurement agreement, significant differences do remain. This presentation will provide an overview of several proposed sources and sinks of NO(sub y) and their regions of importance. Multi-dimensional modeling results for NO(sub y) and its components with comparisons to observations will also be presented.

Evaluation of the atmospheric transport modeling tools used at the Ignalina NPP

International Nuclear Information System (INIS)

Jasiulionis, R.

2004-01-01

The atmospheric transport modeling system at the Ignalina NPP is part of the radionuclide monitoring system and is designed to help associate radionuclide network signals with possible source regions. The evaluation of the Atmospheric Transport Modeling Tools Used at the Ignalina NPP was based on results published in last years. The model based on semi-empirical formulae of turbulent diffusion in the air and local meteorological data were used for calculation of concentration of radionuclides emitted through the Ignalina NPP stack. Meteorological data (wind velocity and direction as well as temperature at a height of 2 and 30 meters) were obtained from the meteorological station of the Ignalina NPP at Visaginas. Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, trajectories of air masses transport to the Ignalina NPP region (56.55 N, 26.57 E) during 95 hours at heights of 100, 500 and 1000 m were calculated. The dispersion in the ground-level air of emissions through the Ignalina NPP stack can also be calculated using the HYSPLIT model. The data on the radionuclide activity concentrations in the air at the measurements site and results of calculation can used for the establishment of their field in the Ignalina NPP region. (author)

Initial conditions and ENSO prediction using a coupled ocean-atmosphere model

Science.gov (United States)

Larow, T. E.; Krishnamurti, T. N.

1998-01-01

A coupled ocean-atmosphere initialization scheme using Newtonian relaxation has been developed for the Florida State University coupled ocean-atmosphere global general circulation model. The initialization scheme is used to initialize the coupled model for seasonal forecasting the boreal summers of 1987 and 1988. The atmosphere model is a modified version of the Florida State University global spectral model, resolution T-42. The ocean general circulation model consists of a slightly modified version of the Hamburg's climate group model described in Latif (1987) and Latif et al. (1993). The coupling is synchronous with information exchanged every two model hours. Using ECMWF atmospheric daily analysis and observed monthly mean SSTs, two, 1-year, time-dependent, Newtonian relaxation were performed using the coupled model prior to conducting the seasonal forecasts. The coupled initializations were conducted from 1 June 1986 to 1 June 1987 and from 1 June 1987 to 1 June 1988. Newtonian relaxation was applied to the prognostic atmospheric vorticity, divergence, temperature and dew point depression equations. In the ocean model the relaxation was applied to the surface temperature. Two, 10-member ensemble integrations were conducted to examine the impact of the coupled initialization on the seasonal forecasts. The initial conditions used for the ensembles are the ocean's final state after the initialization and the atmospheric initial conditions are ECMWF analysis. Examination of the SST root mean square error and anomaly correlations between observed and forecasted SSTs in the Niño-3 and Niño-4 regions for the 2 seasonal forecasts, show closer agreement between the initialized forecast than two, 10-member non-initialized ensemble forecasts. The main conclusion here is that a single forecast with the coupled initialization outperforms, in SST anomaly prediction, against each of the control forecasts (members of the ensemble) which do not include such an initialization

Fair weather atmospheric electricity

International Nuclear Information System (INIS)

Harrison, R G

2011-01-01

Not long after Franklin's iconic studies, an atmospheric electric field was discovered in 'fair weather' regions, well away from thunderstorms. The origin of the fair weather field was sought by Lord Kelvin, through development of electrostatic instrumentation and early data logging techniques, but was ultimately explained through the global circuit model of C.T.R. Wilson. In Wilson's model, charge exchanged by disturbed weather electrifies the ionosphere, and returns via a small vertical current density in fair weather regions. New insights into the relevance of fair weather atmospheric electricity to terrestrial and planetary atmospheres are now emerging. For example, there is a possible role of the global circuit current density in atmospheric processes, such as cloud formation. Beyond natural atmospheric processes, a novel practical application is the use of early atmospheric electrostatic investigations to provide quantitative information on past urban air pollution.

Atmospheric tracer experiments for regional dispersion studies

International Nuclear Information System (INIS)

Heffter, J.L.; Ferber, G.J.

1980-01-01

Tracer experiments are being conducted to verify atmospheric transport and dispersion calculations at distances from tens to hundreds of km from pollutant sources. In one study, a 2 1/2 year sampling program has been carried out at 13 sites located 30 to 140 km from a source of 85 Kr at the Savannah River Plant in South Carolina. Average weekly concentrations as well as twice-daily concentrations were obtained. Sampling data and meteorological data, including surface, tower, and rawinsonde observations are available on magnetic tape for model verification studies. Some verification results for the Air Resources Laboratories Atmospheric Transort and Dispersion Model (ARL-ATAD) are shown for averaging periods from one week to two years

Improving InSAR geodesy using Global Atmospheric Models

Science.gov (United States)

Jolivet, Romain; Agram, Piyush Shanker; Lin, Nina Y.; Simons, Mark; Doin, Marie-Pierre; Peltzer, Gilles; Li, Zhenghong

2014-03-01

Spatial and temporal variations of pressure, temperature, and water vapor content in the atmosphere introduce significant confounding delays in interferometric synthetic aperture radar (InSAR) observations of ground deformation and bias estimates of regional strain rates. Producing robust estimates of tropospheric delays remains one of the key challenges in increasing the accuracy of ground deformation measurements using InSAR. Recent studies revealed the efficiency of global atmospheric reanalysis to mitigate the impact of tropospheric delays, motivating further exploration of their potential. Here we explore the effectiveness of these models in several geographic and tectonic settings on both single interferograms and time series analysis products. Both hydrostatic and wet contributions to the phase delay are important to account for. We validate these path delay corrections by comparing with estimates of vertically integrated atmospheric water vapor content derived from the passive multispectral imager Medium-Resolution Imaging Spectrometer, onboard the Envisat satellite. Generally, the performance of the prediction depends on the vigor of atmospheric turbulence. We discuss (1) how separating atmospheric and orbital contributions allows one to better measure long-wavelength deformation and (2) how atmospheric delays affect measurements of surface deformation following earthquakes, and (3) how such a method allows us to reduce biases in multiyear strain rate estimates by reducing the influence of unevenly sampled seasonal oscillations of the tropospheric delay.

Modeling of hydrological processes in arid agricultural regions

Directory of Open Access Journals (Sweden)

Jiang LI,Xiaomin MAO,Shaozhong KANG,David A. BARRY

2015-12-01

Full Text Available Understanding of hydrological processes, including consideration of interactions between vegetation growth and water transfer in the root zone, underpins efficient use of water resources in arid-zone agriculture. Water transfers take place in the soil-plant-atmosphere continuum, and include groundwater dynamics, unsaturated zone flow, evaporation/transpiration from vegetated/bare soil and surface water, agricultural canal/surface water flow and seepage, and well pumping. Models can be categorized into three classes: (1 regional distributed hydrological models with various land uses, (2 groundwater-soil-plant-atmosphere continuum models that neglect lateral water fluxes, and (3 coupled models with groundwater flow and unsaturated zone water dynamics. This review highlights, in addition, future research challenges in modeling arid-zone agricultural systems, e.g., to effectively assimilate data from remote sensing, and to fully reflect climate change effects at various model scales.

Atmospheric Modeling of the Martian Polar Regions: One Mars Year of CRISM EPF Observations of the South Pole

Science.gov (United States)

Brown, A. J.; Wolff, M. J.

2009-03-01

We have used CRISM Emission Phase Function gimballed observations to investigate atmospheric dust/ice opacity and surface albedo in the south polar region for the first Mars year of MRO operations. This covers the MY28 "dust event" and cap recession.

Coupled atmosphere-wildland fire modelling

Directory of Open Access Journals (Sweden)

Jacques Henri Balbi

2009-10-01

Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.

Atmospheric Transport of Arid Aerosol from Desert Regions of Central Asia

Science.gov (United States)

Chen, Boris; Solomon, Paul; Sitnov, Sergei; Grechko, Evgeny; Maximenkov, Leonid; Artamonova, Maria; Pogarski, Fedor

2010-05-01

Investigation of atmospheric transport of arid aerosol from Central Asia was held within the ISTC project 3715. Particular attention was paid to the removal of aerosol from the Aral Sea region and its further transport, because aerosol and pollutants emission from Central Asia affect the airspace of the entire Asian continent. At the same time measurements of aerosols in the atmosphere of Central Asia are holding in a small number of stations, and currently available data are insufficient to define the initial conditions and/or verification of models of long-range transport. To identify sources of pollution transported from Central Asia, in Kyrgyzstan measurement and sampling of air were organized: at the station on the northern slope of the Kirgiz Range, 30 km south of Bishkek, at an altitude of 1700 m above sea level (Bishkek Site, 42,683N; 74,694E ), and on permanent alpine Teploklyuchenka lidar station in the Central Tien Shan at an altitude of 2000 m above sea level (Lidar Site, 42,467N; 78,533E). The chemical analysis of collected aerosol and soils samples was carried out. Measurements of aerosol at these stations have been merged with the simulation of the trajectories of air masses in the study region and with the satellite (the Terra and Aqua satellites) observations of aerosol optical thickness in this region. Satellite data for the region 43-47 N, and 58-62 E (Aral Sea) from April 2008 to September 2009 were analyzed. The moments were selected, when the value of aerosol optical thickness (AOT) was greatest (more than 0.5), and the transport from the Aral Sea region to the observation sites took place. For each of these days, the forward trajectories, which started at 6 points within the region, were calculated using the HYSPLIT model. The days, on which the trajectories reached the BISHKEK and LIDAR sites, were determined from the data obtained. Calculations on the basis of the RAMS model were performed for these days. These calculations were performed

Combined eye-atmosphere visibility model

Science.gov (United States)

Kaufman, Y. J.

1981-01-01

Existing models of the optical characteristics of the eye are combined with a recent model of optical characteristics of the atmosphere given by its modulation transfer function. This combination results in the combined eye-atmosphere performance given by the product of their modulation transfer functions. An application for the calculation of visibility thresholds in the case of a two-halves field is given.

Single-Column Modeling, GCM Parameterizations and Atmospheric Radiation Measurement Data

International Nuclear Information System (INIS)

Somerville, R.C.J.; Iacobellis, S.F.

2005-01-01

Our overall goal is identical to that of the Atmospheric Radiation Measurement (ARM) Program: the development of new and improved parameterizations of cloud-radiation effects and related processes, using ARM data at all three ARM sites, and the implementation and testing of these parameterizations in global and regional models. To test recently developed prognostic parameterizations based on detailed cloud microphysics, we have first compared single-column model (SCM) output with ARM observations at the Southern Great Plains (SGP), North Slope of Alaska (NSA) and Topical Western Pacific (TWP) sites. We focus on the predicted cloud amounts and on a suite of radiative quantities strongly dependent on clouds, such as downwelling surface shortwave radiation. Our results demonstrate the superiority of parameterizations based on comprehensive treatments of cloud microphysics and cloud-radiative interactions. At the SGP and NSA sites, the SCM results simulate the ARM measurements well and are demonstrably more realistic than typical parameterizations found in conventional operational forecasting models. At the TWP site, the model performance depends strongly on details of the scheme, and the results of our diagnostic tests suggest ways to develop improved parameterizations better suited to simulating cloud-radiation interactions in the tropics generally. These advances have made it possible to take the next step and build on this progress, by incorporating our parameterization schemes in state-of-the-art 3D atmospheric models, and diagnosing and evaluating the results using independent data. Because the improved cloud-radiation results have been obtained largely via implementing detailed and physically comprehensive cloud microphysics, we anticipate that improved predictions of hydrologic cycle components, and hence of precipitation, may also be achievable. We are currently testing the performance of our ARM-based parameterizations in state-of-the--art global and regional

Theoretical oscillation frequencies for solar-type dwarfs from stellar models with <3D >-atmospheres

DEFF Research Database (Denmark)

Jørgensen, Andreas Christ Sølvsten; Weiss, Achim; Mosumgaard, Jakob Rorsted

2017-01-01

We present a new method for replacing the outermost layers of stellar models with interpolated atmospheres based on results from 3D simulations, in order to correct for structural inadequacies of these layers. This replacement is known as patching. Tests, based on 3D atmospheres from three......, and the mismatch in T-eff and log g between the un-patched model and patched 3D atmosphere. We find the eigen frequencies to be unaltered by the patching depth deep within the adiabatic region, while changing the patching quantity or the employed atmosphere grid leads to frequency shifts that may exceed 1 mu Hz....... Likewise, the eigen frequencies are sensitive to mismatches in T-eff or log g. A thorough investigation of the accuracy of a new scheme, for interpolating mean 3D stratifications within the atmosphere grids, is furthermore performed. Throughout large parts of the atmosphere grids, our interpolation scheme...

Hyperspectral material identification on radiance data using single-atmosphere or multiple-atmosphere modeling

Science.gov (United States)

Mariano, Adrian V.; Grossmann, John M.

2010-11-01

Reflectance-domain methods convert hyperspectral data from radiance to reflectance using an atmospheric compensation model. Material detection and identification are performed by comparing the compensated data to target reflectance spectra. We introduce two radiance-domain approaches, Single atmosphere Adaptive Cosine Estimator (SACE) and Multiple atmosphere ACE (MACE) in which the target reflectance spectra are instead converted into sensor-reaching radiance using physics-based models. For SACE, known illumination and atmospheric conditions are incorporated in a single atmospheric model. For MACE the conditions are unknown so the algorithm uses many atmospheric models to cover the range of environmental variability, and it approximates the result using a subspace model. This approach is sometimes called the invariant method, and requires the choice of a subspace dimension for the model. We compare these two radiance-domain approaches to a Reflectance-domain ACE (RACE) approach on a HYDICE image featuring concealed materials. All three algorithms use the ACE detector, and all three techniques are able to detect most of the hidden materials in the imagery. For MACE we observe a strong dependence on the choice of the material subspace dimension. Increasing this value can lead to a decline in performance.

Description and evaluation of the Earth System Regional Climate Model (RegCM-ES)

Science.gov (United States)

Farneti, Riccardo; Sitz, Lina; Di Sante, Fabio; Fuentes-Franco, Ramon; Coppola, Erika; Mariotti, Laura; Reale, Marco; Sannino, Gianmaria; Barreiro, Marcelo; Nogherotto, Rita; Giuliani, Graziano; Graffino, Giorgio; Solidoro, Cosimo; Giorgi, Filippo

2017-04-01

The increasing availability of satellite remote sensing data, of high temporal frequency and spatial resolution, has provided a new and enhanced view of the global ocean and atmosphere, revealing strong air-sea coupling processes throughout the ocean basins. In order to obtain an accurate representation and better understanding of the climate system, its variability and change, the inclusion of all mechanisms of interaction among the different sub-components, at high temporal and spatial resolution, becomes ever more desirable. Recently, global coupled models have been able to progressively refine their horizontal resolution to attempt to resolve smaller-scale processes. However, regional coupled ocean-atmosphere models can achieve even finer resolutions and provide additional information on the mechanisms of air-sea interactions and feedbacks. Here we describe a new, state-of-the-art, Earth System Regional Climate Model (RegCM-ES). RegCM-ES presently includes the coupling between atmosphere, ocean, land surface and sea-ice components, as well as an hydrological and ocean biogeochemistry model. The regional coupled model has been implemented and tested over some of the COordinated Regional climate Downscaling Experiment (CORDEX) domains. RegCM-ES has shown improvements in the representation of precipitation and SST fields over the tested domains, as well as realistic representations of coupled air-sea processes and interactions. The RegCM-ES model, which can be easily implemented over any regional domain of interest, is open source making it suitable for usage by the large scientific community.

Atmospheric dispersion models of radioactivity releases

International Nuclear Information System (INIS)

Oza, R.B.

2016-01-01

In view of the rapid industrialization in recent time, atmospheric dispersion models have become indispensible 'tools' to ensure that the effects of releases are well within the acceptable limits set by the regulatory authority. In the case of radioactive releases from the nuclear facility, though negligible in quantity and many a times not even measurable, it is required to demonstrate the compliance of these releases to the regulatory limits set by the regulatory authority by carrying out radiological impact assessment. During routine operations of nuclear facility, the releases are so low that environmental impact is usually assessed with the help of atmospheric dispersion models as it is difficult to distinguish negligible contribution of nuclear facility to relatively high natural background radiation. The accidental releases from nuclear facility, though with negligible probability of occurrence, cannot be ruled out. In such cases, the atmospheric dispersion models are of great help to emergency planners for deciding the intervention actions to minimize the consequences in public domain and also to workout strategies for the management of situation. In case of accidental conditions, the atmospheric dispersion models are also utilized for the estimation of probable quantities of radionuclides which might have got released to the atmosphere. Thus, atmospheric dispersion models are an essential tool for nuclear facility during routine operation as well as in the case of accidental conditions

Examining Interior Grid Nudging Techniques Using Two-Way Nesting in the WRF Model for Regional Climate Modeling

Science.gov (United States)

This study evaluates interior nudging techniques using the Weather Research and Forecasting (WRF) model for regional climate modeling over the conterminous United States (CONUS) using a two-way nested configuration. NCEP–Department of Energy Atmospheric Model Intercomparison Pro...

Modelling of nonhomogeneous atmosphere in NPP containment using lumped-parameter model based on CFD calculations

International Nuclear Information System (INIS)

Kljenak, I.; Mavko, B.; Babic, M.

2005-01-01

Full text of publication follows: The modelling and simulation of atmosphere mixing and stratification in nuclear power plant containments is a topic, which is currently being intensely investigated. With the increase of computer power, it has now become possible to model these phenomena with a local instantaneous description, using so-called Computational Fluid Dynamics (CFD) codes. However, calculations with these codes still take relatively long times. An alternative faster approach, which is also being applied, is to model nonhomogeneous atmosphere with lumped-parameter codes by dividing larger control volumes into smaller volumes, in which conditions are modelled as homogeneous. The flow between smaller volumes is modelled using one-dimensional approaches, which includes the prescription of flow loss coefficients. However, some authors have questioned this approach, as it appears that atmosphere stratification may sometimes be well simulated only by adjusting flow loss coefficients to adequate 'artificial' values that are case-dependent. To start the resolution of this issue, a modelling of nonhomogeneous atmosphere with a lumped-parameter code is proposed, where the subdivision of a large volume into smaller volumes is based on results of CFD simulations. The basic idea is to use the results of a CFD simulation to define regions, in which the flow velocities have roughly the same direction. These regions are then modelled as control volumes in a lumped-parameter model. In the proposed work, this procedure was applied to a simulation of an experiment of atmosphere mixing and stratification, which was performed in the TOSQAN facility. The facility is located at the Institut de Radioprotection et de Surete Nucleaire (IRSN) in Saclay (France) and consists of a cylindrical vessel (volume: 7 m3), in which gases are injected. In the experiment, which was also proposed for the OECD/NEA International Standard Problem No.47, air was initially present in the vessel, and

Assessing filtering of mountaintop CO2 mole fractions for application to inverse models of biosphere-atmosphere carbon exchange

Directory of Open Access Journals (Sweden)

S. L. Heck

2012-02-01

Full Text Available There is a widely recognized need to improve our understanding of biosphere-atmosphere carbon exchanges in areas of complex terrain including the United States Mountain West. CO2 fluxes over mountainous terrain are often difficult to measure due to unusual and complicated influences associated with atmospheric transport. Consequently, deriving regional fluxes in mountain regions with carbon cycle inversion of atmospheric CO2 mole fraction is sensitive to filtering of observations to those that can be represented at the transport model resolution. Using five years of CO2 mole fraction observations from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON, five statistical filters are used to investigate a range of approaches for identifying regionally representative CO2 mole fractions. Test results from three filters indicate that subsets based on short-term variance and local CO2 gradients across tower inlet heights retain nine-tenths of the total observations and are able to define representative diel variability and seasonal cycles even for difficult-to-model sites where the influence of local fluxes is much larger than regional mole fraction variations. Test results from two other filters that consider measurements from previous and following days using spline fitting or sliding windows are overly selective. Case study examples showed that these windowing-filters rejected measurements representing synoptic changes in CO2, which suggests that they are not well suited to filtering continental CO2 measurements. We present a novel CO2 lapse rate filter that uses CO2 differences between levels in the model atmosphere to select subsets of site measurements that are representative on model scales. Our new filtering techniques provide guidance for novel approaches to assimilating mountain-top CO2 mole fractions in carbon cycle inverse models.

The Regional Earth System Model (RegESM) using RegCM4 coupled with the MITgcm ocean model: First assessments over the MED-CORDEX domain

Science.gov (United States)

Mariotti, Laura; Utku Turunçoǧlu, Ufuk; Farneti, Riccardo; Sannino, Gianmaria; Vittoria Struglia, Maria; Carillo, Adriana; Giorgi, Filippo

2016-04-01

In the framework of global climate studies, there is an increasingly growing concern about the vulnerability of the Mediterranean region, where high population density and intense exploitation activities pose severe questions on the sustainability of terrestrial water management, both for the present and the future. Ocean modeling studies suggest that the Mediterranean thermohaline circulation could be weakened in conditions of global greenhouse warming, an event which would undoubtedly affect regional climate, possibly triggering global feedback processes. Experiments with the atmosphere-ocean coupled system confirmed that a good comprehension of Mediterranean processes requires the explicit inclusion of the feedbacks between the atmospheric and the oceanic components, thus achieving a complete, fully coupled description of the Mediterranean hydrological cycle, at the same time gaining new insights in our current ability to reproduce the atmospheric hydrological processes and to close the hydrological balance. These issues are addressed by the upgraded PROTHEUS system which was jointly developed by ENEA and ICTP. Here we present a first evaluation of the performances of the new PROTHEUS system (called PROTHEUS 2.0) composed by the regional climate model RegCM4 (Giorgi et al. 2012) coupled with both the ocean model MITgcm (Marshall J. et al. 1997a,b) and the HD river model (Max-Planck's HD model; Hagemann and Dümenil, 1998) using RegESM (Regional Earth System Model) as a driver. The three-component (atmosphere, ocean and river routing) fully coupled model exchanges sea surface temperature (SST) from the ocean to the atmospheric model, surface wind stress, energy and freshwater fluxes from the atmosphere to the ocean model, surface and sub-surface runoff from the atmospheric component to the river routing model (Max-Planck's HD model; Hagemann and Dümenil, 1998). In order to have water conservation within the system, the river routing component sends the

Representation of fine scale atmospheric variability in a nudged limited area quasi-geostrophic model: application to regional climate modelling

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Omrani, H.; Drobinski, P.; Dubos, T.

2009-09-01

In this work, we consider the effect of indiscriminate nudging time on the large and small scales of an idealized limited area model simulation. The limited area model is a two layer quasi-geostrophic model on the beta-plane driven at its boundaries by its « global » version with periodic boundary condition. This setup mimics the configuration used for regional climate modelling. Compared to a previous study by Salameh et al. (2009) who investigated the existence of an optimal nudging time minimizing the error on both large and small scale in a linear model, we here use a fully non-linear model which allows us to represent the chaotic nature of the atmosphere: given the perfect quasi-geostrophic model, errors in the initial conditions, concentrated mainly in the smaller scales of motion, amplify and cascade into the larger scales, eventually resulting in a prediction with low skill. To quantify the predictability of our quasi-geostrophic model, we measure the rate of divergence of the system trajectories in phase space (Lyapunov exponent) from a set of simulations initiated with a perturbation of a reference initial state. Predictability of the "global", periodic model is mostly controlled by the beta effect. In the LAM, predictability decreases as the domain size increases. Then, the effect of large-scale nudging is studied by using the "perfect model” approach. Two sets of experiments were performed: (1) the effect of nudging is investigated with a « global » high resolution two layer quasi-geostrophic model driven by a low resolution two layer quasi-geostrophic model. (2) similar simulations are conducted with the two layer quasi-geostrophic LAM where the size of the LAM domain comes into play in addition to the first set of simulations. In the two sets of experiments, the best spatial correlation between the nudge simulation and the reference is observed with a nudging time close to the predictability time.

Surface-Atmosphere Moisture Interactions in the Frozen Ground Regions of Eurasia.

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Ford, Trent W; Frauenfeld, Oliver W

2016-01-18

Climate models simulate an intensifying Arctic hydrologic cycle in response to climatic warming, however the role of surface-atmosphere interactions from degrading frozen ground is unclear in these projections. Using Modern-Era Retrospective Analysis for Research and Applications (MERRA) data in high-latitude Eurasia, we examine long-term variability in surface-atmosphere coupling as represented by the statistical relationship between surface evaporative fraction (EF) and afternoon precipitation. Changes in EF, precipitation, and their statistical association are then related to underlying permafrost type and snow cover. Results indicate significant positive trends in July EF in the Central Siberian Plateau, corresponding to significant increases in afternoon precipitation. The positive trends are only significant over continuous permafrost, with non-significant or negative EF and precipitation trends over isolated, sporadic, and discontinuous permafrost areas. Concurrently, increasing EF and subsequent precipitation are found to coincide with significant trends in May and June snowmelt, which potentially provides the moisture source for the observed enhanced latent heating and moisture recycling in the region. As climate change causes continuous permafrost to transition to discontinuous, discontinuous to sporadic, sporadic to isolated, and isolated permafrost disappears, this will also alter patterns of atmospheric convection, moisture recycling, and hence the hydrologic cycle in high-latitude land areas.

Assessment of the Suitability of High Resolution Numerical Weather Model Outputs for Hydrological Modelling in Mountainous Cold Regions

Science.gov (United States)

Rasouli, K.; Pomeroy, J. W.; Hayashi, M.; Fang, X.; Gutmann, E. D.; Li, Y.

2017-12-01

The hydrology of mountainous cold regions has a large spatial variability that is driven both by climate variability and near-surface process variability associated with complex terrain and patterns of vegetation, soils, and hydrogeology. There is a need to downscale large-scale atmospheric circulations towards the fine scales that cold regions hydrological processes operate at to assess their spatial variability in complex terrain and quantify uncertainties by comparison to field observations. In this research, three high resolution numerical weather prediction models, namely, the Intermediate Complexity Atmosphere Research (ICAR), Weather Research and Forecasting (WRF), and Global Environmental Multiscale (GEM) models are used to represent spatial and temporal patterns of atmospheric conditions appropriate for hydrological modelling. An area covering high mountains and foothills of the Canadian Rockies was selected to assess and compare high resolution ICAR (1 km × 1 km), WRF (4 km × 4 km), and GEM (2.5 km × 2.5 km) model outputs with station-based meteorological measurements. ICAR with very low computational cost was run with different initial and boundary conditions and with finer spatial resolution, which allowed an assessment of modelling uncertainty and scaling that was difficult with WRF. Results show that ICAR, when compared with WRF and GEM, performs very well in precipitation and air temperature modelling in the Canadian Rockies, while all three models show a fair performance in simulating wind and humidity fields. Representation of local-scale atmospheric dynamics leading to realistic fields of temperature and precipitation by ICAR, WRF, and GEM makes these models suitable for high resolution cold regions hydrological predictions in complex terrain, which is a key factor in estimating water security in western Canada.

Online coupled regional meteorology chemistry models in Europe : Current status and prospects

NARCIS (Netherlands)

Baklanov, A.; Schlünzen, K.; Suppan, P.; Baldasano, J.; Brunner, D.; Aksoyoglu, S.; Carmichael, G.; Douros, J.; Flemming, J.; Forkel, R.; Galmarini, S.; Gauss, M.; Grell, G.; Hirtl, M.; Joffre, S.; Jorba, O.; Kaas, E.; Kaasik, M.; Kallos, G.; Kong, X.; Korsholm, U.; Kurganskiy, A.; Kushta, J.; Lohmann, U.; Mahura, A.; Manders-Groot, A.; Maurizi, A.; Moussiopoulos, N.; Rao, S.T.; Savage, N.; Seigneur, C.; Sokhi, R.S.; Solazzo, E.; Solomos, S.; Sørensen, B.; Tsegas, G.; Vignati, E.; Vogel, B.; Zhang, Y.

2014-01-01

Online coupled mesoscale meteorology atmospheric chemistry models have undergone a rapid evolution in recent years. Although mainly developed by the air quality modelling community, these models are also of interest for numerical weather prediction and regional climate modelling as they can consider

Modelling of pollution dispersion in atmosphere

International Nuclear Information System (INIS)

Borysiewicz, M.; Stankiewicz, R.

1994-01-01

The paper contains the review of the mathematical foundation of atmospheric dispersion models. The atmospheric phenomena relevant to atmospheric dispersion model are discussed. In particular the parametrization of processes with time and space scales smaller than numerical grid size, limited by available computer power, is presented. The special attention was devoted to similarity theory and parametrization of boundary layer. The numerical methods are analysed and the drawbacks of the method are presented. (author). 99 refs, 15 figs, 3 tabs

Simulation of a Large Wildfire in a Coupled Fire-Atmosphere Model

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Jean-Baptiste Filippi

2018-06-01

Full Text Available The Aullene fire devastated more than 3000 ha of Mediterranean maquis and pine forest in July 2009. The simulation of combustion processes, as well as atmospheric dynamics represents a challenge for such scenarios because of the various involved scales, from the scale of the individual flames to the larger regional scale. A coupled approach between the Meso-NH (Meso-scale Non-Hydrostatic atmospheric model running in LES (Large Eddy Simulation mode and the ForeFire fire spread model is proposed for predicting fine- to large-scale effects of this extreme wildfire, showing that such simulation is possible in a reasonable time using current supercomputers. The coupling involves the surface wind to drive the fire, while heat from combustion and water vapor fluxes are injected into the atmosphere at each atmospheric time step. To be representative of the phenomenon, a sub-meter resolution was used for the simulation of the fire front, while atmospheric simulations were performed with nested grids from 2400-m to 50-m resolution. Simulations were run with or without feedback from the fire to the atmospheric model, or without coupling from the atmosphere to the fire. In the two-way mode, the burnt area was reproduced with a good degree of realism at the local scale, where an acceleration in the valley wind and over sloping terrain pushed the fire line to locations in accordance with fire passing point observations. At the regional scale, the simulated fire plume compares well with the satellite image. The study explores the strong fire-atmosphere interactions leading to intense convective updrafts extending above the boundary layer, significant downdrafts behind the fire line in the upper plume, and horizontal wind speeds feeding strong inflow into the base of the convective updrafts. The fire-induced dynamics is induced by strong near-surface sensible heat fluxes reaching maximum values of 240 kW m − 2 . The dynamical production of turbulent kinetic

Differences in rain rate intensities between TRMM observations and community atmosphere model simulations

Science.gov (United States)

Deng, Yi; Bowman, Kenneth P.; Jackson, Charles

2007-01-01

Precipitation related latent heating is important in driving the atmospheric general circulation and in generating intraseasonal to decadal atmospheric variability. Our ability to project future climate change, especially trends in costly precipitation extremes, hinges upon whether coupled GCMs capture processes that affect precipitation characteristics. Our study compares the tropical-subtropical precipitation characteristics of simulations by the NCAR CAM3.1 atmospheric GCM and observations derived from the NASA Tropical Rainfall Measuring Mission (TRMM) satellite. Despite a fairly good simulation of the annual mean rain rate, CAM rains about 10-50% more often than the real world and fails to capture heavy rainfall associated with deep convective systems over subtropical South America and U.S. Southern Plains. When it rains, there is a likelihood of 0.96-1.0 that it rains lightly in the model, compared to values of 0.84-1.0 in TRMM data. On the other hand, the likelihood of the occurrence of moderate to heavy rainfall is an order of magnitude higher in observations (0.12-0.2) than that in the model (model compensates for the lack of heavy precipitation through raining more frequently within the light rain category, which leads to an annual rainfall amount close to what is observed. CAM captures the qualitative change of rain rate PDF from a "dry" oceanic to a "wet" oceanic region, but it fails to simulate the change of precipitation characteristics from an oceanic region to a land region where thunderstorm rainfall dominates.

Advances in understanding, models and parameterisations of biosphere-atmosphere ammonia exchange

Science.gov (United States)

Flechard, C. R.; Massad, R.-S.; Loubet, B.; Personne, E.; Simpson, D.; Bash, J. O.; Cooter, E. J.; Nemitz, E.; Sutton, M. A.

2013-03-01

Atmospheric ammonia (NH3) dominates global emissions of total reactive nitrogen (Nr), while emissions from agricultural production systems contribute about two thirds of global NH3 emissions; the remaining third emanates from oceans, natural vegetation, humans, wild animals and biomass burning. On land, NH3 emitted from the various sources eventually returns to the biosphere by dry deposition to sink areas, predominantly semi-natural vegetation, and by wet and dry deposition as ammonium (NH4+) to all surfaces. However, the land/atmosphere exchange of gaseous NH3 is in fact bi-directional over unfertilized as well as fertilized ecosystems, with periods and areas of emission and deposition alternating in time (diurnal, seasonal) and space (patchwork landscapes). The exchange is controlled by a range of environmental factors, including meteorology, surface layer turbulence, thermodynamics, air and surface heterogeneous-phase chemistry, canopy geometry, plant development stage, leaf age, organic matter decomposition, soil microbial turnover, and, in agricultural systems, by fertilizer application rate, fertilizer type, soil type, crop type, and agricultural management practices. We review the range of processes controlling NH3 emission and uptake in the different parts of the soil-canopy-atmosphere continuum, with NH3 emission potentials defined at the substrate and leaf levels by different [NH4+] / [H+] ratios (Γ). Surface/atmosphere exchange models for NH3 are necessary to compute the temporal and spatial patterns of emissions and deposition at the soil, plant, field, landscape, regional and global scales, in order to assess the multiple environmental impacts of air-borne and deposited NH3 and NH4+. Models of soil/vegetation/atmosphereem NH3 exchange are reviewed from the substrate and leaf scales to the global scale. They range from simple steady-state, "big leaf" canopy resistance models, to dynamic, multi-layer, multi-process, multi

Nuclear analytical techniques applied to characterization of atmospheric aerosols in Amazon Region

International Nuclear Information System (INIS)

Gerab, Fabio; Artaxo, Paulo

1996-01-01

This work presents the atmospheric aerosols characterization that exist in different regions of Amazon basin. The biogenic aerosol emission by forest, as well as the atmospheric emissions of particulate materials due to biomass burning, were analyzed. Samples of aerosol particles were collected during three years in two different locations of Amazon region using Stacked Unit Filters. In order to study these samples some analytical nuclear techniques were used. The high concentrations of aerosols as a result of biomass burning process were observed in the period of june-september

Experiments with a Regional Vector-Vorticity Model, and Comparison with Other Models

Science.gov (United States)

Konor, C. S.; Dazlich, D. A.; Jung, J.; Randall, D. A.

2017-12-01

The Vector-Vorticity Model (VVM) is an anelastic model with a unique dynamical core that predicts the three-dimensional vorticity instead of the three-dimensional momentum. The VVM is used in the CRMs of the Global Quasi-3D Multiscale Modeling Framework, which is discussed by Joon-Hee Jung and collaborators elsewhere in this session. We are updating the physics package of the VVM, replacing it with the physics package of the System for Atmosphere Modeling (SAM). The new physics package includes a double-moment microphysics, Mellor-Yamada turbulence, Monin-Obukov surface fluxes, and the RRTMG radiation parameterization. We briefly describe the VVM and show results from standard test cases, including TWP-ICE. We compare the results with those obtained using the earlier physics. We also show results from experiments on convection aggregation in radiative-convective equilibrium, and compare with those obtained using both SAM and the Regional Atmospheric Modeling System (RAMS).

Recent advances in non-LTE stellar atmosphere models

Science.gov (United States)

Sander, Andreas A. C.

2017-11-01

In the last decades, stellar atmosphere models have become a key tool in understanding massive stars. Applied for spectroscopic analysis, these models provide quantitative information on stellar wind properties as well as fundamental stellar parameters. The intricate non-LTE conditions in stellar winds dictate the development of adequate sophisticated model atmosphere codes. The increase in both, the computational power and our understanding of physical processes in stellar atmospheres, led to an increasing complexity in the models. As a result, codes emerged that can tackle a wide range of stellar and wind parameters. After a brief address of the fundamentals of stellar atmosphere modeling, the current stage of clumped and line-blanketed model atmospheres will be discussed. Finally, the path for the next generation of stellar atmosphere models will be outlined. Apart from discussing multi-dimensional approaches, I will emphasize on the coupling of hydrodynamics with a sophisticated treatment of the radiative transfer. This next generation of models will be able to predict wind parameters from first principles, which could open new doors for our understanding of the various facets of massive star physics, evolution, and death.

Methane Fluxes in West Siberia: 3-D Regional Model Simulation

International Nuclear Information System (INIS)

Jagovkina, S. V.; Karol, I. L.; Zubov, V. A.; Lagun, V. E.; Reshetnikov, A. I.; Rozanov, E. V.

2001-01-01

The West Siberian region is one of the main contributors of the atmospheric greenhouse gas methane due to the large areas of wetlands, rivers, lakes and numerous gas deposits situated there.But there are no reliable estimations of integral methane flux from this area into the atmosphere. For assessment of methane fluxes in West Siberia the specially constructed 3-D regional chemical transport model was applied. The 3-D distribution of methane is calculated on the basis of the current meteorological data fields(wind, temperature, geopotential) updated 4 times a day. The methane concentrations measured near the main gas fields of West Siberia in the summer season of 1999, were used for correction of methane flux intensity estimates obtained previously by comparison of measurements carried out in summer 1993 and 1996 with modelled methane mixing ratio distribution. This set of field and model experiments confirmed the preliminary conclusion about low leakage intensity: anthropogenic methane flux does not exceed 5-15% of total summer methane flux, estimated as 11-12 Mt CH 4 in summer from this region, in spite of the large areas of gas deposits located there

Atmospheric water vapor transport: Estimation of continental precipitation recycling and parameterization of a simple climate model. M.S. Thesis

Science.gov (United States)

Brubaker, Kaye L.; Entekhabi, Dara; Eagleson, Peter S.

1991-01-01

The advective transport of atmospheric water vapor and its role in global hydrology and the water balance of continental regions are discussed and explored. The data set consists of ten years of global wind and humidity observations interpolated onto a regular grid by objective analysis. Atmospheric water vapor fluxes across the boundaries of selected continental regions are displayed graphically. The water vapor flux data are used to investigate the sources of continental precipitation. The total amount of water that precipitates on large continental regions is supplied by two mechanisms: (1) advection from surrounding areas external to the region; and (2) evaporation and transpiration from the land surface recycling of precipitation over the continental area. The degree to which regional precipitation is supplied by recycled moisture is a potentially significant climate feedback mechanism and land surface-atmosphere interaction, which may contribute to the persistence and intensification of droughts. A simplified model of the atmospheric moisture over continents and simultaneous estimates of regional precipitation are employed to estimate, for several large continental regions, the fraction of precipitation that is locally derived. In a separate, but related, study estimates of ocean to land water vapor transport are used to parameterize an existing simple climate model, containing both land and ocean surfaces, that is intended to mimic the dynamics of continental climates.

Infrared radiation models for atmospheric methane

Science.gov (United States)

Cess, R. D.; Kratz, D. P.; Caldwell, J.; Kim, S. J.

1986-01-01

Mutually consistent line-by-line, narrow-band and broad-band infrared radiation models are presented for methane, a potentially important anthropogenic trace gas within the atmosphere. Comparisons of the modeled band absorptances with existing laboratory data produce the best agreement when, within the band models, spurious band intensities are used which are consistent with the respective laboratory data sets, but which are not consistent with current knowledge concerning the intensity of the infrared fundamental band of methane. This emphasizes the need for improved laboratory band absorptance measurements. Since, when applied to atmospheric radiation calculations, the line-by-line model does not require the use of scaling approximations, the mutual consistency of the band models provides a means of appraising the accuracy of scaling procedures. It is shown that Curtis-Godson narrow-band and Chan-Tien broad-band scaling provide accurate means of accounting for atmospheric temperature and pressure variations.

Development of a regional hydrologic soil model and application to the Beerze-Reusel drainage basin

International Nuclear Information System (INIS)

Kolditz, O.; Du, Y.; Buerger, C.; Delfs, J.; Kuntz, D.; Beinhorn, M.; Hess, M.; Wang, W.; Grift, B. van der; Stroet, C. te

2007-01-01

The soil compartment is an important interface between the atmosphere and the subsurface hydrosphere. In this paper a conceptual approach for regional hydrologic soil modelling (RHSM) is presented, which provides two important qualities for modelling. First, the soil compartment is directly coupled to the atmosphere via the land surface and to the aquifers. Second, extremely fine (5 cm vertical) resolutions of the soil system can be realized at regional scales (several hundreds of km 2 ). This high-resolution modelling could be achieved by parallel computation techniques. The RHSM approach is applied to the Beerze-Reusel drainage basin, which belongs to the Meuse River basin. Moisture transport in the soil system was calculated with extremely high vertical resolution at a regional scale based on rainfall-evaporation data for the year 2000. As a result, highly resolved regional groundwater recharge pattern addressing the heterogeneity of soil systems could be determined. - A real case application of concept of regional hydrologic soil modelling is presented

Recent developments in the applications of the Regional Atmospheric Modeling System (RAMS) for emergency response planning and operational forecasting at the Kennedy Space Center

International Nuclear Information System (INIS)

Lyons, W.A.; Tremback, C.J.

1996-01-01

The authors will summarize ten years of developing and applying the Regional Atmospheric Modeling System (RAMS) to emergency response and operational dispersion forecasting at the Kennedy Space Center (KSC). RAMS forms the core of two workstation-based operational systems, ERDAS (the Emergency Response Dose Assessment System) and PROWESS (Parallelized RAMS Operational Weather Simulation System) which are undergoing extensive operational testing prior to potential deployment as part of the range forecasting system at KSC. RAMS has been interfaced with HYPACT (the Hybrid Particle and Concentration Transport Model) to produce detailed 3-D dispersion forecasts from a variety of sources including cold spills, routine launch operations, and explosive conflagrations of launch vehicles

Modelling the mid-Pliocene Warm Period climate with the IPSL coupled model and its atmospheric component LMDZ5A

Directory of Open Access Journals (Sweden)

C. Contoux

2012-06-01

Full Text Available This paper describes the experimental design and model results of the climate simulations of the mid-Pliocene Warm Period (mPWP, ca. 3.3–3 Ma using the Institut Pierre Simon Laplace model (IPSLCM5A, in the framework of the Pliocene Model Intercomparison Project (PlioMIP. We use the IPSL atmosphere ocean general circulation model (AOGCM, and its atmospheric component alone (AGCM, to simulate the climate of the mPWP. Boundary conditions such as sea surface temperatures (SSTs, topography, ice-sheet extent and vegetation are derived from the ones imposed by the Pliocene Model Intercomparison Project (PlioMIP, described in Haywood et al. (2010, 2011. We first describe the IPSL model main features, and then give a full description of the boundary conditions used for atmospheric model and coupled model experiments. The climatic outputs of the mPWP simulations are detailed and compared to the corresponding control simulations. The simulated warming relative to the control simulation is 1.94 °C in the atmospheric and 2.07 °C in the coupled model experiments. In both experiments, warming is larger at high latitudes. Mechanisms governing the simulated precipitation patterns are different in the coupled model than in the atmospheric model alone, because of the reduced gradients in imposed SSTs, which impacts the Hadley and Walker circulations. In addition, a sensitivity test to the change of land-sea mask in the atmospheric model, representing a sea-level change from present-day to 25 m higher during the mid-Pliocene, is described. We find that surface temperature differences can be large (several degrees Celsius but are restricted to the areas that were changed from ocean to land or vice versa. In terms of precipitation, impact on polar regions is minor although the change in land-sea mask is significant in these areas.

Interannual modes of variability of Southern Hemisphere atmospheric circulation in CMIP3 models

International Nuclear Information System (INIS)

Grainger, S; Frederiksen, C S; Zheng, X

2010-01-01

The atmospheric circulation acts as a bridge between large-scale sources of climate variability, and climate variability on regional scales. Here a statistical method is applied to monthly mean Southern Hemisphere 500hPa geopotential height to separate the interannual variability of the seasonal mean into intraseasonal and slowly varying (time scales of a season or longer) components. Intraseasonal and slow modes of variability are estimated from realisations of models from the Coupled Model Intercomparison Project Phase 3 (CMIP3) twentieth century coupled climate simulation (20c3m) and are evaluated against those estimated from reanalysis data. The intraseasonal modes of variability are generally well reproduced across all CMIP3 20c3m models for both Southern Hemisphere summer and winter. The slow modes are in general less well reproduced than the intraseasonal modes, and there are larger differences between realisations than for the intraseasonal modes. New diagnostics are proposed to evaluate model variability. It is found that differences between realisations from each model are generally less than inter-model differences. Differences between model-mean diagnostics are found. The results obtained are applicable to assessing the reliability of changes in atmospheric circulation variability in CMIP3 models and for their suitability for further studies of regional climate variability.

Atmospheric circulation in regional climate models over Central Europe: links to surface air temperature and the influence of driving data

Energy Technology Data Exchange (ETDEWEB)

Plavcova, Eva [Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic, Prague 4 (Czech Republic); Technical University, Department of Applied Mathematics, Liberec (Czech Republic); Charles University, Faculty of Mathematics and Physics, Prague (Czech Republic); Kysely, Jan [Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic, Prague 4 (Czech Republic); Technical University, Department of Applied Mathematics, Liberec (Czech Republic)

2012-10-15

The study examines simulation of atmospheric circulation, represented by circulation indices (flow direction, strength and vorticity), and links between circulation and daily surface air temperatures in regional climate models (RCMs) over Central Europe. We explore control simulations of five high-resolution RCMs from the ENSEMBLES project driven by re-analysis (ERA-40) and the same global climate model (ECHAM5 GCM) plus of one RCM (RCA) driven by different GCMs. The aims are to (1) identify errors in RCM-simulated distributions of circulation indices in individual seasons, (2) identify errors in simulated temperatures under particular circulation indices, and (3) compare performance of individual RCMs with respect to the driving data. Although most of the RCMs qualitatively reflect observed distributions of the airflow indices, each produces distributions significantly different from the observations. General biases include overestimation of the frequency of strong flow days and of strong cyclonic vorticity. Some circulation biases obviously propagate from the driving data. ECHAM5 and all simulations driven by ECHAM5 underestimate frequency of easterly flow, mainly in summer. Except for HIRHAM, however, all RCMs driven by ECHAM5 improve on the driving GCM in simulating atmospheric circulation. The influence on circulation characteristics in the nested RCM differs between GCMs, as demonstrated in a set of RCA simulations with different driving data. The driving data control on circulation in RCA is particularly weak for the BCM GCM, in which case RCA substantially modifies (but does not improve) the circulation from the driving data in both winter and summer. Those RCMs with the most distorted atmospheric circulation are HIRHAM driven by ECHAM5 and RCA driven by BCM. Relatively strong relationships between circulation indices and surface air temperatures were found in the observed data for Central Europe. The links differ by season and are usually stronger for

Atmospheric circulation in regional climate models over Central Europe: links to surface air temperature and the influence of driving data

International Nuclear Information System (INIS)

Plavcova, Eva; Kysely, Jan

2012-01-01

The study examines simulation of atmospheric circulation, represented by circulation indices (flow direction, strength and vorticity), and links between circulation and daily surface air temperatures in regional climate models (RCMs) over Central Europe. We explore control simulations of five high-resolution RCMs from the ENSEMBLES project driven by re-analysis (ERA-40) and the same global climate model (ECHAM5 GCM) plus of one RCM (RCA) driven by different GCMs. The aims are to (1) identify errors in RCM-simulated distributions of circulation indices in individual seasons, (2) identify errors in simulated temperatures under particular circulation indices, and (3) compare performance of individual RCMs with respect to the driving data. Although most of the RCMs qualitatively reflect observed distributions of the airflow indices, each produces distributions significantly different from the observations. General biases include overestimation of the frequency of strong flow days and of strong cyclonic vorticity. Some circulation biases obviously propagate from the driving data. ECHAM5 and all simulations driven by ECHAM5 underestimate frequency of easterly flow, mainly in summer. Except for HIRHAM, however, all RCMs driven by ECHAM5 improve on the driving GCM in simulating atmospheric circulation. The influence on circulation characteristics in the nested RCM differs between GCMs, as demonstrated in a set of RCA simulations with different driving data. The driving data control on circulation in RCA is particularly weak for the BCM GCM, in which case RCA substantially modifies (but does not improve) the circulation from the driving data in both winter and summer. Those RCMs with the most distorted atmospheric circulation are HIRHAM driven by ECHAM5 and RCA driven by BCM. Relatively strong relationships between circulation indices and surface air temperatures were found in the observed data for Central Europe. The links differ by season and are usually stronger for

Regional modelling of polycyclic aromatic hydrocarbons: WRF-Chem-PAH model development and East Asia case studies

Science.gov (United States)

Mu, Qing; Lammel, Gerhard; Gencarelli, Christian N.; Hedgecock, Ian M.; Chen, Ying; Přibylová, Petra; Teich, Monique; Zhang, Yuxuan; Zheng, Guangjie; van Pinxteren, Dominik; Zhang, Qiang; Herrmann, Hartmut; Shiraiwa, Manabu; Spichtinger, Peter; Su, Hang; Pöschl, Ulrich; Cheng, Yafang

2017-10-01

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere are not yet well understood. We extended the regional atmospheric chemistry model WRF-Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low-concentration, slowly degrading semivolatile compounds. The WRF-Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity, i.e. phenanthrene, chrysene and benzo[a]pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF-Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new species and to correct the transport problems can be applied to other newly implemented species in WRF-Chem.

Regional modelling of anthropogenic sulphur in Southeast Asia

Science.gov (United States)

Engardt, M.; Leong, C. P.

A co-operative research project between the Malaysian Meteorological Service (MMS) and the Swedish Meteorological and Hydrological Institute (SMHI) focussing on the usage of an atmospheric transport and chemistry model, has just been initiated. Here, we describe the main features of the dispersion model and discuss a first set of calculations in light of available measurements of sulphuric species in Southeast Asia. According to our results, anthropogenic sulphur concentrations and depositions are particularly high near the large cities of the region, around a metal smelter in the southern Philippines, and in a region extending from northern Vietnam into southeastern China. These areas coincide with the high-emissions regions of Southeast Asia and we tentatively conclude that regional transport of acidifying species is not as far-reaching as in the mid-latitudes. From our calculations, and from supporting measurements we conclude that most of rural Southeast Asia is not yet severely affected by anthropogenic sulphur, but given the rapid rate of economical development in this region the situation may deteriorate quickly. Areas that are particularly at risk include the large cities, northern Vietnam, most of central Thailand, most of peninsular Malaysia, eastern Sumatra and parts of Java, all of which receive total-sulphur depositions in excess of 0.5 g S m -2 yr -1. Our model simulates sulphate in precipitation in accordance with measurements, but it has a tendency to overestimate atmospheric SO 2. It remains to be investigated whether this is a problem in the model formulation or a result of unrepresentative sampling. An immediate continuation of this study should be performed with higher spatial resolution than the currently used 100×100 km 2. Other imperfections in this model study, which should be addressed in future work, include parameterised vertical transport in deep convective clouds, the influence of natural emissions (primarily from volcanoes) on the

Multi-model global assessment of subseasonal prediction skill of atmospheric rivers

Science.gov (United States)

Deflorio, M. J.

2017-12-01

Atmospheric rivers (ARs) are global phenomena that are characterized by long, narrow plumes of water vapor transport. They are most often observed in the midlatitudes near climatologically active storm track regions. Because of their frequent association with floods, landslides, and other hydrological impacts on society, there is significant incentive at the intersection of academic research, water management, and policymaking to understand the skill with which state-of-the-art operational weather models can predict ARs weeks-to-months in advance. We use the newly assembled Subseasonal-to-Seasonal (S2S) database, which includes extensive hindcast records of eleven operational weather models, to assess global prediction skill of atmospheric rivers on S2S timescales. We develop a metric to assess AR skill that is suitable for S2S timescales by counting the total number of AR days which occur over each model and observational grid cell during a 2-week time window. This "2-week AR occurrence" metric is suitable for S2S prediction skill assessment because it does not consider discrete hourly or daily AR objects, but rather a smoothed representation of AR occurrence over a longer period of time. Our results indicate that several of the S2S models, especially the ECMWF model, show useful prediction skill in the 2-week forecast window, with significant interannual variation in some regions. We also present results from an experimental forecast of S2S AR prediction skill using the ECMWF and NCEP models.

GPS atmosphere sounding project - An innovative approach for the recovery of atmospheric parameters. WP 232 - Validation of regional models - BALTEX - and contributions to WP 341 and WP 344

Energy Technology Data Exchange (ETDEWEB)

Johnsen, K.P.

2003-07-01

The atmospheric water vapor content is one of the most important parameters for the hydrological cycle. In order to investigate the energy and water balance over the BALTEX study region this report describes comparisons of specific humidity profiles of the hydrostatic High resolution Regional weather forecast Model HRM of the Deutscher Wetterdienst (DWD) with profiles derived from spaceborne radio occultation data of GPS/MET and CHAMP and comparisons with the vertically integrated water vapor (IWV) of different networks of groundbased GPS receivers within Europe. High correlations (with a correlation coefficient around 0.9) between the HRM IWV and GPS IWV were found. It is shown that the analysis data used to initialize the HRM model can explain a large part of the mean difference between the IWV from the model and the GPS data. Specific humidities and the IWVs were determined from the refractivity profiles of the radio occultations of GPS/MET and CHAMP/GPS using an iterative algorithm of Gorbunov and Sokolovski (1993). The comparisons of the specific humidity profiles have shown that both receivers, GPS/MET and CHAMP/GPS, measure significantly lower mean specific humidities below about 4 km than HRM. This is e.g. supported by comparisons between the HRM model and the ECMWF analysis data, between the HRM model and radiosonde ascents at Lindenberg/Germany (which have shown lower mean absolute differences of about 0.2 g/kg) as well as between HRM and further spaceborne data like AMSU-A/B and TERRA/MODIS. Comparisons between CHAMP/GPS and AMSU-A over oceans and AMSU-B over Antarctica show the high value of GPS radio occultations for applications worldwide. (orig.)

A conceptual prediction model for seasonal drought processes using atmospheric and oceanic standardized anomalies and its application to four recent severe regional drought events in China

Science.gov (United States)

Liu, Z.; LU, G.; He, H.; Wu, Z.; He, J.

2017-12-01

Reliable drought prediction is fundamental for seasonal water management. Considering that drought development is closely related to the spatio-temporal evolution of large-scale circulation patterns, we develop a conceptual prediction model of seasonal drought processes based on atmospheric/oceanic Standardized Anomalies (SA). It is essentially the synchronous stepwise regression relationship between 90-day-accumulated atmospheric/oceanic SA-based predictors and 3-month SPI updated daily (SPI3). It is forced with forecasted atmospheric and oceanic variables retrieved from seasonal climate forecast systems, and it can make seamless drought prediction for operational use after a year-to-year calibration. Simulation and prediction of four severe seasonal regional drought processes in China were forced with the NCEP/NCAR reanalysis datasets and the NCEP Climate Forecast System Version 2 (CFSv2) operationally forecasted datasets, respectively. With the help of real-time correction for operational application, model application during four recent severe regional drought events in China revealed that the model is good at development prediction but weak in severity prediction. In addition to weakness in prediction of drought peak, the prediction of drought relief is possible to be predicted as drought recession. This weak performance may be associated with precipitation-causing weather patterns during drought relief. Based on initial virtual analysis on predicted 90-day prospective SPI3 curves, it shows that the 2009/2010 drought in Southwest China and 2014 drought in North China can be predicted and simulated well even for the prospective 1-75 day. In comparison, the prospective 1-45 day may be a feasible and acceptable lead time for simulation and prediction of the 2011 droughts in Southwest China and East China, after which the simulated and predicted developments clearly change.

Parameterization of dust emissions in the global atmospheric chemistry-climate model EMAC: impact of nudging and soil properties

OpenAIRE

Astitha, M.; Lelieveld, J.; Kader, M. Abdel; Pozzer, A.; de Meij, A.

2012-01-01

Airborne desert dust influences radiative transfer, atmospheric chemistry and dynamics, as well as nutrient transport and deposition. It directly and indirectly affects climate on regional and global scales. Two versions of a parameterization scheme to compute desert dust emissions are incorporated into the atmospheric chemistry general circulation model EMAC (ECHAM5/MESSy2.41 Atmospheric Chemistry). One uses a global...

Med-CORDEX: a first coordinated inter-comparison of high-resolution and fully coupled regional climate models for the Mediterranean

Science.gov (United States)

Somot, Samuel

2015-04-01

Due to its geographical, meteorological and oceanographic features, the Mediterranean region can be considered as one of the best place to test and use regional climate modelling tools. It has been chosen as one of the CORDEX sub-domain (MED) leading to the Med-CORDEX initiative. This open and voluntary initiative, financially supported by MISTRALS/HyMeX, has been proposed by the Mediterranean climate modelling research community as a follow-up of previous initiatives. In addition to the CORDEX-like simulations (Atmosphere-RCM, 50 km, ERA-Interim and GCM driven runs), Med-CORDEX includes additional simulations to experiment some of the regional climate modelling current challenges. We present here the status and results of these additional simulations dedicated to the use of (1) very high-resolution Regional Climate Models (RCM, up to 10 km) and (2) fully coupled Regional Climate System Models (RCSM), coupling the various components of the regional climate (atmosphere, land surface and hydrology, river and ocean). Today, Med-CORDEX gathers 23 different modelling groups from 9 different countries (France, Italy, Spain, Serbia, Turkey, Greece, Tunisia, Germany, Hungary) in Europe, Middle-East and North-Africa. They use 12 different atmosphere RCMs including land-surface representation, 4 river models, 10 regional ocean models and 12 different Regional Climate System Models. Almost all the simulations planned (Evaluation, Historical and Scenarios modes) have been completed by the modelling teams. More than half of the runs are archived and freely available for non-commercial use through a dedicated database hosted at ENEA at www.medcordex.eu in common and standardized netcdf format (265,000 files and 3.6 Tb uploaded). This includes atmosphere-only, ocean-only and fully coupled regional climate models. In particular multi-model regional ocean simulations have been archived in a common and standardized format for the first time in the history of the Mediterranean Sea

Regional Climate Modeling and Remote Sensing to Characterize Impacts of Civil War Driven Land Use Change on Regional Hydrology and Climate

Science.gov (United States)

Maksimowicz, M.; Masarik, M. T.; Brandt, J.; Flores, A. N.

2016-12-01

Land use/land cover (LULC) change directly impacts the partitioning of surface mass and energy fluxes. Regional-scale weather and climate are potentially altered by LULC if the resultant changes in partitioning of surface energy fluxes are extensive enough. Dynamics of land use, particularly those related to the social dimensions of the Earth System, are often simplified or not represented in regional land-atmosphere models. This study explores the role of LULC change on a regional hydroclimate system, focusing on potential hydroclimate changes arising from an extended civil conflict in Mozambique. Civil war from 1977-1992 in Mozambique led to land use change at a regional scale as a result of the collapse of large herbivore populations due to poaching. Since the war ended, farming has increased, poaching was curtailed, and animal populations were reintroduced. In this study LULC in a region encompassing Gorongosa is classified at three instances between 1977 to 2015 using Landsat imagery. We use these derived LULC datasets to inform lower boundary conditions in the Weather Research and Forecasting (WRF) model. To quantify potential hydrometeorological changes arising from conflict-driven land use change, we performed a factorial-like experiment by mixing input LULC maps and atmospheric forcing data from before, during, and after the civil war. Analysis of the Landsat data shows measurable land cover change from 1977-present as tree cover encroached into grasslands. Initial tests show corresponding sensitivities to different LULC schemes within the WRF model. Preliminary results suggest that the war did indeed impact regional hydroclimate in a significant way via its direct and indirect impacts on land-atmosphere interactions. Results of this study suggest that LULC change arising from regional conflicts are a potentially understudied, yet important human process to capture in both regional reanalyses and climate change projections.

Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

Energy Technology Data Exchange (ETDEWEB)

Katata, G.; Chino, M.; Kobayashi, T. [Japan Atomic Energy Agency (JAEA), Ibaraki (Japan); and others

2015-07-01

Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric and oceanic transport, dispersion and deposition models. The atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition scheme, which deals with dry and fog-water depositions, cloud condensation nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I{sub 2} and CH{sub 3}I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The results revealed that the major releases of radionuclides due to the FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, midnight of 14 March when the SRV (safety relief valve) was opened three times at Unit 2, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of release rates. The simulation by WSPEEDI-II using the new source term reproduced the local and regional patterns of

Lithosphere-Surfacesphere–Atmosphere-Ionosphere coupling model for Vrancea seismic zone in Romania

Energy Technology Data Exchange (ETDEWEB)

Zoran, Maria; Savastru, Roxana; Savastru, Dan [National Institute of R& D for Optoelectronics, MG5 Bucharest -Magurele, 077125 Romania, maria@dnt.ro (Romania)

2016-03-25

This paper presents a complex multidisciplinary approach concept to explain the nature of short-term earthquake precursors observed in land surface, atmosphere, ionosphere and magnetosphere for strong intermediate depth earthquakes recorded in Vrancea region in Romania. A developed Lithosphere-Surfacesphere-Atmosphere-Ionosphere (LSAI) coupling model can explain most of these presignals as a synergy between different anomalies of geophysical/geochemical parameters. These anomalies prior to medium to strong earthquakes are attributed to the thermodynamic, degassing and ionization processes in the Earth-Atmosphere system and micro-fracturing in the rocks especially along area’s active faults. The main outcome of this paper is an unified concept for systematic validation of different types of earthquake precursors of which Land Surface Temperature (LST), outgoing Long wave Radiation (OLR), Surface Latent Heat Flux (SLHF), Air Temperature (AT), radon gas concentration, ionospheric Total Electron Content (TEC) are the most reliable parameters within the chain of the processes described by LSAI model.

Modeling the wind-fields of accidental releases with an operational regional forecast model

International Nuclear Information System (INIS)

Albritton, J.R.; Lee, R.L.; Sugiyama, G.

1995-01-01

The Atmospheric Release Advisory Capability (ARAC) is an operational emergency preparedness and response organization supported primarily by the Departments of Energy and Defense. ARAC can provide real-time assessments of atmospheric releases of radioactive materials at any location in the world. ARAC uses robust three-dimensional atmospheric transport and dispersion models, extensive geophysical and dose-factor databases, meteorological data-acquisition systems, and an experienced staff. Although it was originally conceived and developed as an emergency response and assessment service for nuclear accidents, the ARAC system has been adapted to also simulate non-radiological hazardous releases. For example, in 1991 ARAC responded to three major events: the oil fires in Kuwait, the eruption of Mt. Pinatubo in the Philippines, and the herbicide spill into the upper Sacramento River in California. ARAC's operational simulation system, includes two three-dimensional finite-difference models: a diagnostic wind-field scheme, and a Lagrangian particle-in-cell transport and dispersion scheme. The meteorological component of ARAC's real-time response system employs models using real-time data from all available stations near the accident site to generate a wind-field for input to the transport and dispersion model. Here we report on simulation studies of past and potential release sites to show that even in the absence of local meteorological observational data, readily available gridded analysis and forecast data and a prognostic model, the Navy Operational Regional Atmospheric Prediction System, applied at an appropriate grid resolution can successfully simulate complex local flows

Uncertainties in United States agricultural N2O emissions: comparing forward model simulations to atmospheric N2O data.

Science.gov (United States)

Nevison, C. D.; Saikawa, E.; Dlugokencky, E. J.; Andrews, A. E.; Sweeney, C.

2014-12-01

Atmospheric N2O concentrations have increased from 275 ppb in the preindustrial to about 325 ppb in recent years, a ~20% increase with important implications for both anthropogenic greenhouse forcing and stratospheric ozone recovery. This increase has been driven largely by synthetic fertilizer production and other perturbations to the global nitrogen cycle associated with human agriculture. Several recent regional atmospheric inversion studies have quantified North American agricultural N2O emissions using top-down constraints based on atmospheric N2O data from the National Oceanic and Atmospheric Administration (NOAA) Global Greenhouse Gas Reference Network, including surface, aircraft and tall tower platforms. These studies have concluded that global N2O inventories such as EDGAR may be underestimating the true U.S. anthropogenic N2O source by a factor of 3 or more. However, simple back-of-the-envelope calculations show that emissions of this magnitude are difficult to reconcile with the basic constraints of the global N2O budget. Here, we explore some possible reasons why regional atmospheric inversions might overestimate the U.S. agricultural N2O source. First, the seasonality of N2O agricultural sources is not well known, but can have an important influence on inversion results, particularly when the inversions are based on data that are concentrated in the spring/summer growing season. Second, boundary conditions can strongly influence regional inversions but the boundary conditions used may not adequately account for remote influences on surface data such as the seasonal stratospheric influx of N2O-depleted air. We will present a set of forward model simulations, using the Community Land Model (CLM) and two atmospheric chemistry tracer transport models, MOZART and the Whole Atmosphere Community Climate Model (WACCM), that examine the influence of terrestrial emissions and atmospheric chemistry and dynamics on atmospheric variability in N2O at U.S. and

Sensitivity of boreal-summer circulation and precipitation to atmospheric aerosols in selected regions – Part 2: The Americas

Directory of Open Access Journals (Sweden)

G. Walker

2009-10-01

Full Text Available Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4 general circulation model (GCM to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Africa, and North and South America. Part 1 of this paper addresses the responses to aerosol perturbations in India and Africa. This paper presents the same for aerosol perturbations over the Americas. GEOS-4 is forced with prescribed aerosols based on climatological data, which interact with clouds using a prognostic scheme for cloud microphysics including aerosol nucleation of water and ice cloud hydrometeors. In clear-sky conditions the aerosols interact with radiation. Thus the model includes comprehensive physics describing the aerosol direct and indirect effects on climate (hereafter ADE and AIE respectively. Each simulation is started from analyzed initial conditions for 1 May and was integrated through June-July-August of each of the six years: 1982–1987 to provide a 6-ensemble set. Results are presented for the difference between simulations with double the climatological aerosol concentration and one-half the climatological aerosol concentration for three experiments: two where the ADE and AIE are applied separately and one in which both the ADE and AIE are applied. The ADE and AIE both yield reductions in net radiation at the top of the atmosphere and surface while the direct absorption of shortwave radiation contributes a net radiative heating in the atmosphere. A large net heating of the atmosphere is also apparent over the subtropical North Atlantic Ocean that is attributable to the large aerosol perturbation imposed over Africa. This atmospheric warming and the depression of the surface pressure over North America contribute to a northward shift of the inter-Tropical Convergence Zone over northern South America, an increase in

Sensitivity of boreal-summer circulation and precipitation to atmospheric aerosols in selected regions &ndash Part 2: The Americas

Directory of Open Access Journals (Sweden)

E. M. Wilcox

2009-10-01

Full Text Available Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4 general circulation model (GCM to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Africa, and North and South America. Part 1 of this paper addresses the responses to aerosol perturbations in India and Africa. This paper presents the same for aerosol perturbations over the Americas. GEOS-4 is forced with prescribed aerosols based on climatological data, which interact with clouds using a prognostic scheme for cloud microphysics including aerosol nucleation of water and ice cloud hydrometeors. In clear-sky conditions the aerosols interact with radiation. Thus the model includes comprehensive physics describing the aerosol direct and indirect effects on climate (hereafter ADE and AIE respectively. Each simulation is started from analyzed initial conditions for 1 May and was integrated through June-July-August of each of the six years: 1982–1987 to provide a 6-ensemble set. Results are presented for the difference between simulations with double the climatological aerosol concentration and one-half the climatological aerosol concentration for three experiments: two where the ADE and AIE are applied separately and one in which both the ADE and AIE are applied. The ADE and AIE both yield reductions in net radiation at the top of the atmosphere and surface while the direct absorption of shortwave radiation contributes a net radiative heating in the atmosphere. A large net heating of the atmosphere is also apparent over the subtropical North Atlantic Ocean that is attributable to the large aerosol perturbation imposed over Africa. This atmospheric warming and the depression of the surface pressure over North America contribute to a northward shift of the inter-Tropical Convergence Zone over northern South America, an increase in

Water Vapor Tacers as Diagnostics of the Regional Atmospheric Hydrologic Cycle

Science.gov (United States)

Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

2000-01-01

Understanding of the local and remote sources of water vapor can be a valuable diagnostic in understanding the regional atmospheric hydrologic cycle, especially in North America where moisture transport and local evaporation are important sources of water for precipitation. In the present study, we have implemented passive tracers as prognostic variables to follow water vapor evaporated in predetermined regions until the water tracer precipitates. All evaporative sources of water are accounted for by tracers, and the water vapor variable provides the validation of the tracer water and the formulation of the sources and sinks. The Geostationary Operational Environmental Satellites General Circulation Model (GEOS GCM) is used to simulate several summer periods to determine the source regions of precipitation for the United States and India. Using this methodology, a detailed analysis of the recycling of water, interannual variability of the sources of water and links to the Great Plains low-level jet and North American monsoon will be presented. Potential uses in GCM sensitivity studies, predictability studies and data assimilation especially regarding the North American monsoon and GEWEX America Prediction Project (GAPP) will be discussed.

Implementing earth observation and advanced satellite based atmospheric sounders for water resource and climate modelling

DEFF Research Database (Denmark)

Boegh, E.; Dellwik, Ebba; Hahmann, Andrea N.

2010-01-01

This paper discusses preliminary remote sensing (MODIS) based hydrological modelling results for the Danish island Sjælland (7330 km2) in relation to project objectives and methodologies of a new research project “Implementing Earth observation and advanced satellite based atmospheric sounders....... For this purpose, a) internal catchment processes will be studied using a Distributed Temperature Sensing (DTS) system, b) Earth observations will be used to upscale from field to regional scales, and c) at the largest scale, satellite based atmospheric sounders and meso-scale climate modelling will be used...

Stellar atmosphere modeling of extremely hot, compact stars

Science.gov (United States)

Rauch, Thomas; Ringat, Ellen; Werner, Klaus

Present X-ray missions like Chandra and XMM-Newton provide excellent spectra of extremely hot white dwarfs, e.g. burst spectra of novae. Their analysis requires adequate NLTE model atmospheres. The Tuebingen Non-LTE Model-Atmosphere Package (TMAP) can calculate such model at-mospheres and spectral energy distributions at a high level of sophistication. We present a new grid of models that is calculated in the parameter range of novae and supersoft X-ray sources and show examples of their application.

Immersion freezing by natural dust based on a soccer ball model with the Community Atmospheric Model version 5: climate effects

Science.gov (United States)

Wang, Yong; Liu, Xiaohong

2014-12-01

We introduce a simplified version of the soccer ball model (SBM) developed by Niedermeier et al (2014 Geophys. Res. Lett. 41 736-741) into the Community Atmospheric Model version 5 (CAM5). It is the first time that SBM is used in an atmospheric model to parameterize the heterogeneous ice nucleation. The SBM, which was simplified for its suitable application in atmospheric models, uses the classical nucleation theory to describe the immersion/condensation freezing by dust in the mixed-phase cloud regime. Uncertain parameters (mean contact angle, standard deviation of contact angle probability distribution, and number of surface sites) in the SBM are constrained by fitting them to recent natural dust (Saharan dust) datasets. With the SBM in CAM5, we investigate the sensitivity of modeled cloud properties to the SBM parameters, and find significant seasonal and regional differences in the sensitivity among the three SBM parameters. Changes of mean contact angle and the number of surface sites lead to changes of cloud properties in Arctic in spring, which could be attributed to the transport of dust ice nuclei to this region. In winter, significant changes of cloud properties induced by these two parameters mainly occur in northern hemispheric mid-latitudes (e.g., East Asia). In comparison, no obvious changes of cloud properties caused by changes of standard deviation can be found in all the seasons. These results are valuable for understanding the heterogeneous ice nucleation behavior, and useful for guiding the future model developments.

Immersion freezing by natural dust based on a soccer ball model with the Community Atmospheric Model version 5: climate effects

International Nuclear Information System (INIS)

Wang, Yong; Liu, Xiaohong

2014-01-01

We introduce a simplified version of the soccer ball model (SBM) developed by Niedermeier et al (2014 Geophys. Res. Lett. 41 736–741) into the Community Atmospheric Model version 5 (CAM5). It is the first time that SBM is used in an atmospheric model to parameterize the heterogeneous ice nucleation. The SBM, which was simplified for its suitable application in atmospheric models, uses the classical nucleation theory to describe the immersion/condensation freezing by dust in the mixed-phase cloud regime. Uncertain parameters (mean contact angle, standard deviation of contact angle probability distribution, and number of surface sites) in the SBM are constrained by fitting them to recent natural dust (Saharan dust) datasets. With the SBM in CAM5, we investigate the sensitivity of modeled cloud properties to the SBM parameters, and find significant seasonal and regional differences in the sensitivity among the three SBM parameters. Changes of mean contact angle and the number of surface sites lead to changes of cloud properties in Arctic in spring, which could be attributed to the transport of dust ice nuclei to this region. In winter, significant changes of cloud properties induced by these two parameters mainly occur in northern hemispheric mid-latitudes (e.g., East Asia). In comparison, no obvious changes of cloud properties caused by changes of standard deviation can be found in all the seasons. These results are valuable for understanding the heterogeneous ice nucleation behavior, and useful for guiding the future model developments. (letter)

Quantifying regional changes in terrestrial carbon storage by extrapolation from local ecosystem models

Energy Technology Data Exchange (ETDEWEB)

King, A W

1991-12-31

A general procedure for quantifying regional carbon dynamics by spatial extrapolation of local ecosystem models is presented Monte Carlo simulation to calculate the expected value of one or more local models, explicitly integrating the spatial heterogeneity of variables that influence ecosystem carbon flux and storage. These variables are described by empirically derived probability distributions that are input to the Monte Carlo process. The procedure provides large-scale regional estimates based explicitly on information and understanding acquired at smaller and more accessible scales.Results are presented from an earlier application to seasonal atmosphere-biosphere CO{sub 2} exchange for circumpolar ``subarctic`` latitudes (64{degree}N-90{degree}N). Results suggest that, under certain climatic conditions, these high northern ecosystems could collectively release 0.2 Gt of carbon per year to the atmosphere. I interpret these results with respect to questions about global biospheric sinks for atmospheric CO{sub 2} .

Midlatitude D region variations measured from broadband radio atmospherics

Science.gov (United States)

Han, Feng

The high power, broadband very low frequency (VLF, 3--30 kHz) and extremely low frequency (ELF, 3--3000 Hz) electromagnetic waves generated by lightning discharges and propagating in the Earth-ionosphere waveguide can be used to measure the average electron density profile of the lower ionosphere (D region) across the wave propagation path due to several reflections by the upper boundary (lower ionosphere) of the waveguide. This capability makes it possible to frequently and even continuously monitor the D region electron density profile variations over geographically large regions, which are measurements that are essentially impossible by other means. These guided waves, usually called atmospherics (or sferics for short), are recorded by our sensors located near Duke University. The purpose of this work is to develop and implement algorithms to derive the variations of D region electron density profile which is modeled by two parameters (one is height and another is sharpness), by comparing the recorded sferic spectra to a series of model simulated sferic spectra from using a finite difference time domain (FDTD) code. In order to understand the time scales, magnitudes and sources for the midlatitude nighttime D region variations, we analyzed the sferic data of July and August 2005, and extracted both the height and sharpness of the D region electron density profile. The heights show large temporal variations of several kilometers on some nights and the relatively stable behavior on others. Statistical calculations indicate that the hourly average heights during the two months range between 82.0 km and 87.2 km with a mean value of 84.9 km and a standard deviation of 1.1 km. We also observed spatial variations of height as large as 2.0 km over 5 degrees latitudes on some nights, and no spatial variation on others. In addition, the measured height variations exhibited close correlations with local lightning occurrence rate on some nights but no correlation with local

Coupled Photochemical and Condensation Model for the Venus Atmosphere

Science.gov (United States)

Bierson, Carver; Zhang, Xi; Mendonca, Joao; Liang, Mao-Chang

2017-10-01

Ground based and Venus Express observations have provided a wealth of information on the vertical and latitudinal distribution of many chemical species in the Venus atmosphere [1,2]. Previous 1D models have focused on the chemistry of either the lower [3] or middle atmosphere [4,5]. Photochemical models focusing on the sulfur gas chemistry have also been independent from models of the sulfuric acid haze and cloud formation [6,7]. In recent years sulfur-bearing particles have become important candidates for the observed SO2 inversion above 80 km [5]. To test this hypothesis it is import to create a self-consistent model that includes photochemistry, transport, and cloud condensation.In this work we extend the domain of the 1D chemistry model of Zhang et al. (2012) [5] to encompass the region between the surface to 110 km. This model includes a simple sulfuric acid condensation scheme with gravitational settling. It simultaneously solves for the chemistry and condensation allowing for self-consistent cloud formation. We compare the resulting chemical distributions to observations at all altitudes. We have also validated our model cloud mass against pioneer Venus observations [8]. This updated full atmosphere chemistry model is also being applied in our 2D solver (altitude and altitude). With this 2D model we can model how the latitudinal distribution of chemical species depends on the meridional circulation. This allows us to use the existing chemical observations to place constraints on Venus GCMs [9-11].References: [1] Arney et al., JGR:Planets, 2014 [2] Vandaele et al., Icarus 2017 (pt. 1 & 2) [3] Krasnopolsky, Icarus, 2007 [4] Krasnopolsky, Icarus, 2012 [5] Zhang et al., Icarus 2012 [6] Gao et al., Icarus, 2014 [7] Krasnopolsky, Icarus, 2015 [8] Knollenberg and Hunten, JGR:Space Physics, 1980 [9] Lee et al., JGR:Planets, 2007 [10] Lebonnois et al., Towards Understanding the Climate of Venus, 2013 [11] Mendoncca and Read, Planetary and Space Science, 2016

Inter-annual variabilities in biogeophysical feedback of terrestrial ecosystem to atmosphere using a land surface model

Science.gov (United States)

Seo, C.; Hong, S.; Jeong, H. M.; Jeon, J.

2017-12-01

Biogeophysical processes of terrestrial ecosystem such as water vapor and energy flux are the key features to understand ecological feedback to atmospheric processes and thus role of terrestrial ecosystem in climate system. For example, it has been recently known that the ecological feedback through water vapor and energy flux results in regulating regional weathers and climates which is one of the fundamental functions of terrestrial ecosystem. In regional scale, water vapor flux has been known to give negative feedback to atmospheric warming, while energy flux from the surface has been known to positive feedback. In this study, we explored the inter-annual variabilities in these two biogeophysical features to see how the climate regulating functions of terrestrial ecosystem have been changed with climate change. We selected a land surface model involving vegetation dynamics that is forced by atmospheric data from NASA including precipitation, temperature, wind, surface pressure, humidity, and incoming radiations. From the land surface model, we simulated 60-year water vapor and energy fluxes from 1961 to 2010, and calculates feedbacks of terrestrial ecosystem as in radiation amount into atmosphere. Then, we analyzed the inter-annual variabilities in the feedbacks. The results showed that some mid-latitude areas showing very high variabilities in precipitation showed higher positive feedback and/or lower negative feedback. These results suggest deterioration of the biogeophyisical factor of climate regulating function over those regions.

Atmospheric weighting functions and surface partial derivatives for remote sensing of scattering planetary atmospheres in thermal spectral region: general adjoint approach

International Nuclear Information System (INIS)

Ustinov, Eugene A.

2005-01-01

An approach to formulation of inversion algorithms for remote sensing in the thermal spectral region in the case of a scattering planetary atmosphere, based on the adjoint equation of radiative transfer (Ustinov (JQSRT 68 (2001) 195; JQSRT 73 (2002) 29); referred to as Papers 1 and 2, respectively, in the main text), is applied to the general case of retrievals of atmospheric and surface parameters for the scattering atmosphere with nadir viewing geometry. Analytic expressions for corresponding weighting functions for atmospheric parameters and partial derivatives for surface parameters are derived. The case of pure atmospheric absorption with a scattering underlying surface is considered and convergence to results obtained for the non-scattering atmospheres (Ustinov (JQSRT 74 (2002) 683), referred to as Paper 3 in the main text) is demonstrated

Models for infrared atmospheric radiation

Science.gov (United States)

Tiwari, S. N.

1976-01-01

Line and band models for infrared spectral absorption are discussed. Radiative transmittance and integrated absorptance of Lorentz, Doppler, and voigt line profiles were compared for a range of parameters. It was found that, for the intermediate path lengths, the combined Lorentz-Doppler (Voigt) profile is essential in calculating the atmospheric transmittance. Narrow band model relations for absorptance were used to develop exact formulations for total absorption by four wide band models. Several continuous correlations for the absorption of a wide band model were compared with the numerical solutions of the wide band models. By employing the line-by-line and quasi-random band model formulations, computational procedures were developed for evaluating transmittance and upwelling atmospheric radiance. Homogeneous path transmittances were calculated for selected bands of CO, CO2, and N2O and compared with experimental measurements. The upwelling radiance and signal change in the wave number interval of the CO fundamental band were also calculated.

Sensitivity of regional meteorology and atmospheric composition during the DISCOVER-AQ period to subgrid-scale cloud-radiation interactions

Science.gov (United States)

Huang, X.; Allen, D. J.; Herwehe, J. A.; Alapaty, K. V.; Loughner, C.; Pickering, K. E.

2014-12-01

Subgrid-scale cloudiness directly influences global and regional atmospheric radiation budgets by attenuating shortwave radiation, leading to suppressed convection, decreased surface precipitation as well as other meteorological parameter changes. We use the latest version of WRF (v3.6, Apr 2014), which incorporates the Kain-Fritsch (KF) convective parameterization to provide subgrid-scale cloud fraction and condensate feedback to the rapid radiative transfer model-global (RRTMG) shortwave and longwave radiation schemes. We apply the KF scheme to simulate the DISCOVER-AQ Maryland field campaign (July 2011), and compare the sensitivity of meteorological parameters to the control run that does not include subgrid cloudiness. Furthermore, we will examine the chemical impact from subgrid cloudiness using a regional chemical transport model (CMAQ). There are several meteorological parameters influenced by subgrid cumulus clouds that are very important to air quality modeling, including changes in surface temperature that impact biogenic emission rates; changes in PBL depth that affect pollutant concentrations; and changes in surface humidity levels that impact peroxide-related reactions. Additionally, subgrid cumulus clouds directly impact air pollutant concentrations by modulating photochemistry and vertical mixing. Finally, we will compare with DISCOVER-AQ flight observation data and evaluate how well this off-line CMAQ simulation driven by WRF with the KF scheme simulates the effects of regional convection on atmospheric composition.

Atmospheric pollution. From processes to modelling

International Nuclear Information System (INIS)

Sportisse, B.

2008-01-01

Air quality, greenhouse effect, ozone hole, chemical or nuclear accidents.. All these phenomena are tightly linked to the chemical composition of atmosphere and to the atmospheric dispersion of pollutants. This book aims at supplying the main elements of understanding of 'atmospheric pollutions': stakes, physical processes involved, role of scientific expertise in decision making. Content: 1 - classifications and scales: chemical composition of the atmosphere, vertical structure, time scales (transport, residence); 2 - matter/light interaction: notions of radiative transfer, application to the Earth's atmosphere; 3 - some elements about the atmospheric boundary layer: notion of scales in meteorology, atmospheric boundary layer (ABL), thermal stratification and stability, description of ABL turbulence, elements of atmospheric dynamics, some elements about the urban climate; 4 - notions of atmospheric chemistry: characteristics, ozone stratospheric chemistry, ozone tropospheric chemistry, brief introduction to indoor air quality; 5 - aerosols, clouds and rains: aerosols and particulates, aerosols and clouds, acid rains and leaching; 6 - towards numerical simulation: equation of reactive dispersion, numerical methods for chemistry-transport models, numerical resolution of the general equation of aerosols dynamics (GDE), modern simulation chains, perspectives. (J.S.)

Modeling of atmospheric pollutant transfers

International Nuclear Information System (INIS)

Jourdain, F.

2007-01-01

Modeling is today a common tool for the evaluation of the environmental impact of atmospheric pollution events, for the design of air monitoring networks or for the calculation of pollutant concentrations in the ambient air. It is even necessary for the a priori evaluation of the consequences of a pollution plume. A large choice of atmospheric transfer codes exist but no ideal tool is available which allows to model all kinds of situations. The present day approach consists in combining different types of modeling according to the requested results and simulations. The CEA has a solid experience in this domain and has developed independent tools for the impact and safety studies relative to industrial facilities and to the management of crisis situations. (J.S.)

Modeling of spectral atmosphere transmission for infrared radiation

International Nuclear Information System (INIS)

Wiecek, B.; Olbrycht, R.

2009-01-01

IR radiation transmission of the atmosphere is an important factor during the thermovision remote sensing and measurement. Transmission coefficient of the atmosphere depends on its content and it is attenuated mainly due to the vapor concentration. Every calibrated thermal camera should be equipped with the digital system which implements the transmission model of the atmosphere. The model presented in this work is based on Beer and Bouguer laws. The proposed simplified model of transmission atmosphere is suitable for implementation in the thermal cameras. A simple digital controller of the camera can calculate the transmission coefficient and correct the temperature measurement. The model takes in account both scattering and absorption due the quantum effects when the photons are interacting with the molecules. (author)

Analysis of the Effects of SST and Model Resolutions on the Identification of the 1993 Superstorm Using an Ocean-Atmosphere Coupled Regional System

Science.gov (United States)

Aktas, D.; Velissariou, P.; Chassignet, E.; Bourassa, M. A.

2014-12-01

The non-tropical storm, the 12-14 March 1993 Superstorm, which called the Storm of the Century had a wide reaching effect on the Northern Gulf of Mexico region and the East Coast of the United States. Previous studies show that the initial development of the storm could not be simulated accurately enough to represent the intensity and the evolution of the storm over the Gulf of Mexico region. The aim of this study is to identify the effects of the air-sea fluxes, the sea surface temperature (SST) and the model resolution on determining the intensity and the track of the storm more accurately. To this end, the outputs from two-way coupled model runs were examined to analyze the storm characteristics. Model configurations have been set within a coupled system framework that includes the atmospheric model Weather Research & Forecasting Model (WRF) and the ocean model Regional Ocean Model (ROMS). Three WRF domains assigned 15 km, 5 km and ~1.6 km resolutions, respectively and an 8 km resolution ROMS domain were used in the coupled system. The initial and boundary conditions for WRF were extracted from the NCEP Climate Forecast System Reanalysis (CFSR) products and the Hybrid Coordinate Ocean Model (HYCOM) generated SSTs while, the conditions for ROMS were extracted from HYCOM. Comparisons were performed against NOAA buoys and GridSAT brightness temperatures. Minimum mean sea level pressure (MSLP), maximum wind speed and storm locations were examined. Time series for MSLP and wind speed were used to illustrate how air-sea interaction and resolution changes storm intensity along the track. The results showing the RMS differences on the storm location and intensity of the storm are also presented.

Interannual Tropical Rainfall Variability in General Circulation Model Simulations Associated with the Atmospheric Model Intercomparison Project.

Science.gov (United States)

Sperber, K. R.; Palmer, T. N.

1996-11-01

The interannual variability of rainfall over the Indian subcontinent, the African Sahel, and the Nordeste region of Brazil have been evaluated in 32 models for the period 1979-88 as part of the Atmospheric Model Intercomparison Project (AMIP). The interannual variations of Nordeste rainfall are the most readily captured, owing to the intimate link with Pacific and Atlantic sea surface temperatures. The precipitation variations over India and the Sahel are less well simulated. Additionally, an Indian monsoon wind shear index was calculated for each model. Evaluation of the interannual variability of a wind shear index over the summer monsoon region indicates that the models exhibit greater fidelity in capturing the large-scale dynamic fluctuations than the regional-scale rainfall variations. A rainfall/SST teleconnection quality control was used to objectively stratify model performance. Skill scores improved for those models that qualitatively simulated the observed rainfall/El Niño- Southern Oscillation SST correlation pattern. This subset of models also had a rainfall climatology that was in better agreement with observations, indicating a link between systematic model error and the ability to simulate interannual variations.A suite of six European Centre for Medium-Range Weather Forecasts (ECMWF) AMIP runs (differing only in their initial conditions) have also been examined. As observed, all-India rainfall was enhanced in 1988 relative to 1987 in each of these realizations. All-India rainfall variability during other years showed little or no predictability, possibly due to internal chaotic dynamics associated with intraseasonal monsoon fluctuations and/or unpredictable land surface process interactions. The interannual variations of Nordeste rainfall were best represented. The State University of New York at Albany/National Center for Atmospheric Research Genesis model was run in five initial condition realizations. In this model, the Nordeste rainfall

Characterization of regional atmospheric aerosols over Hungary by PIXE elemental analysis

International Nuclear Information System (INIS)

Koltay, E.; Szabo, G.; Borbely Kiss, I.; Somorjai, E.; Kiss, A.Z.

1994-01-01

Studying the characteristic features of atmospheric aerosols emitted by natural and anthropogenic sources is of basic importance for a detailed understanding of the physics and chemistry of the atmosphere. Environmental pollution by atmospheric aerosols and their impact can be tested in the same way, too. The separation of natural and anthropogenic components of the aerosol can be done through enrichment factors and size distribution curves deduced from analytical information. The Particle Induced X-ray Emission (PIXE) technique has been applied in aerosol studies by the authors. Results obtained on atmospheric aerosols collected over Hungary and presented in terms of concentrations, enrichment factors, regional signatures, deposition velocities, transport properties and apportionment of sources illustrate the scope and proportions of the potential contribution of PIXE to the methodology of atmospheric aerosol studies. Continued activity planned in the framework of the present CRP may widen the scope of the investigations mainly in the field of size-fractioned sampling and - possibly - in the direction of individual characterization of aerosol particles. (author). 14 refs

[Characteristics of Winter Atmospheric Mixing Layer Height in Beijing-Tianjin-Hebei Region and Their Relationship with the Atmospheric Pollution].

Science.gov (United States)

Li, Meng; Tang, Gui-qian; Huang, Jun; Liu, Zi-rui; An, Jun-lin; Wang, Yue-si

2015-06-01

Atmospheric mixing layer height (MLH) is one of the main factors affecting the atmospheric diffusion and plays an important role in air quality assessment and distribution of the pollutants. Based on the ceilometers data, this paper has made synchronous observation on MLH in Beijing-Tianjin-Hebei region (Beijing, Tianjin, Shijiazhuang and Qinhuangdao) in heavy polluted February 2014 and analyzed the respective overall change and its regional features. Results show that in February 2014,the average of mixing layer height in Qinhuangdao is the highest, up to 865 +/- 268 m, and in Shijiazhuang is the lowest (568 +/- 207 m), Beijing's and Tianjin's are in between, 818 +/- 319 m and 834 +/- 334 m respectively; Combined with the meteorological data, we find that radiation and wind speed are main factors of the mixing layer height; The relationship between the particle concentration and mixing layer height in four sites suggests that mixing layer is less than 800 m, concentration of fine particulate matter in four sites will exceed the national standard (GB 3095-2012, 75 microg x m(-3)). During the period of observation, the proportion of days that mixing layer is less than 800 m in Beijing, Tianjin, Shijiazhuang and Qinhuangdao are 50%, 43%, 80% and 50% respectively. Shijiazhuang though nearly formation contaminant concentration is high, within the atmospheric mixed layer pollutant load is not high. Unfavorable atmospheric diffusion conditions are the main causes of heavy pollution in Shijiazhuang for a long time. The results of the study are of great significance for cognitive Beijing-Tianjin-Hebei area pollution distribution, and can provide a scientific reference for reasonable distribution of regional pollution sources.

Nitrous Oxide Emissions from Biofuel Crops and Atmospheric Aerosols: Associations with Air Quality and Regional Climate

Science.gov (United States)

Pillai, Priya Ramachandran

Emissions of greenhouse gases (GHG) and primary release and secondary formation of aerosols alter the earth's radiative balance and therefore have important climatic implications. Savings in carbon dioxide (CO2) emissions accomplished by replacing fossil fuels with biofuels may increase the nitrous oxide (N2O) emissions. Among various atmospheric trace gases, N2O, irrespective of its low atmospheric concentration, is the fourth most important gas in causing the global greenhouse effect. Major processes, those affect the concentration of atmospheric N2O, are soil microbial activities leading to nitrification and denitrification. Therefore, anthropogenic activities such as industrial emissions, and agricultural practices including application of nitrogenous fertilizers, land use changes, biomass combustion all contribute to the atmospheric N2O concentration. The emission rates of N2O related to biofuel production depend on the nitrogen (N) fertilizer uptake efficiency of biofuel crops. However, crops with less N demand, such as switchgrass may have more favorable climate impacts when compared to crops with high N demands, such as corn. Despite its wide environmental tolerance, the regional adaptability of the potential biofuel crop switch grass varies considerably. Therefore, it is important to regionally quantify the GHG emissions and crop yield in response to N-fertilization. A major objective of this study is to quantify soil emissions of N2O from switchgrass and corn fields as a function of N-fertilization. The roles of soil moisture and soil temperature on N2O fluxes were analyzed. These N2O observations may be used to parameterize the biogeochemical models to better understand the impact of different N2O emission scenarios. This study allows for improvements in climate models that focus on understanding the environmental impacts of the climate change mitigation strategy of replacing fossil fuels with biofuels. As a second major objective, the top of the

The Role of Temporal Evolution in Modeling Atmospheric Emissions from Tropical Fires

Science.gov (United States)

Marlier, Miriam E.; Voulgarakis, Apostolos; Shindell, Drew T.; Faluvegi, Gregory S.; Henry, Candise L.; Randerson, James T.

2014-01-01

Fire emissions associated with tropical land use change and maintenance influence atmospheric composition, air quality, and climate. In this study, we explore the effects of representing fire emissions at daily versus monthly resolution in a global composition-climate model. We find that simulations of aerosols are impacted more by the temporal resolution of fire emissions than trace gases such as carbon monoxide or ozone. Daily-resolved datasets concentrate emissions from fire events over shorter time periods and allow them to more realistically interact with model meteorology, reducing how often emissions are concurrently released with precipitation events and in turn increasing peak aerosol concentrations. The magnitude of this effect varies across tropical ecosystem types, ranging from smaller changes in modeling the low intensity, frequent burning typical of savanna ecosystems to larger differences when modeling the short-term, intense fires that characterize deforestation events. The utility of modeling fire emissions at a daily resolution also depends on the application, such as modeling exceedances of particulate matter concentrations over air quality guidelines or simulating regional atmospheric heating patterns.

Infrared radiation models for atmospheric ozone

Science.gov (United States)

Kratz, David P.; Ces, Robert D.

1988-01-01

A hierarchy of line-by-line, narrow-band, and broadband infrared radiation models are discussed for ozone, a radiatively important atmospheric trace gas. It is shown that the narrow-band (Malkmus) model is in near-precise agreement with the line-by-line model, thus providing a means of testing narrow-band Curtis-Godson scaling, and it is found that this scaling procedure leads to errors in atmospheric fluxes of up to 10 percent. Moreover, this is a direct consequence of the altitude dependence of the ozone mixing ratio. Somewhat greater flux errors arise with use of the broadband model, due to both a lesser accuracy of the broadband scaling procedure and to inherent errors within the broadband model, despite the fact that this model has been tuned to the line-by-line model.

Performance engineering in the community atmosphere model

International Nuclear Information System (INIS)

Worley, P; Mirin, A; Drake, J; Sawyer, W

2006-01-01

The Community Atmosphere Model (CAM) is the atmospheric component of the Community Climate System Model (CCSM) and is the primary consumer of computer resources in typical CCSM simulations. Performance engineering has been an important aspect of CAM development throughout its existence. This paper briefly summarizes these efforts and their impacts over the past five years

Impacts of spectral nudging on the simulated surface air temperature in summer compared with the selection of shortwave radiation and land surface model physics parameterization in a high-resolution regional atmospheric model

Science.gov (United States)

Park, Jun; Hwang, Seung-On

2017-11-01

The impact of a spectral nudging technique for the dynamical downscaling of the summer surface air temperature in a high-resolution regional atmospheric model is assessed. The performance of this technique is measured by comparing 16 analysis-driven simulation sets of physical parameterization combinations of two shortwave radiation and four land surface model schemes of the model, which are known to be crucial for the simulation of the surface air temperature. It is found that the application of spectral nudging to the outermost domain has a greater impact on the regional climate than any combination of shortwave radiation and land surface model physics schemes. The optimal choice of two model physics parameterizations is helpful for obtaining more realistic spatiotemporal distributions of land surface variables such as the surface air temperature, precipitation, and surface fluxes. However, employing spectral nudging adds more value to the results; the improvement is greater than using sophisticated shortwave radiation and land surface model physical parameterizations. This result indicates that spectral nudging applied to the outermost domain provides a more accurate lateral boundary condition to the innermost domain when forced by analysis data by securing the consistency with large-scale forcing over a regional domain. This consequently indirectly helps two physical parameterizations to produce small-scale features closer to the observed values, leading to a better representation of the surface air temperature in a high-resolution downscaled climate.

Modeling of air currents in the Gulf Region

International Nuclear Information System (INIS)

Sullivan, T.J.; Ellis, J.S.; Foster, C.S.; Foster, K.T.; Baskett, R.L.; Nasstrom, J.S.; Schalk, W.W.

1992-01-01

The Atmospheric Release Advisory Capability modeled the wind flow in the Gulf Region in order to make projections of the Kuwait oil fires pollution dispersion. Extensive meteorological models incorporating explicit terrain influences to the flow fields were routinely employed through a six month international assessment support effort organized by the World Meteorological Organization and US scientific research agencies. Results show generally close agreement with visible imagery of the smoke plumes as detected by meteorological satellites. However, there are some examples of significant disagreement or failure of the meteorological models. These failures are most likely directly linked to missing or unavailable weather observations

Modeling the effects of atmospheric emissions on groundwater composition

International Nuclear Information System (INIS)

Brown, T.J.

1994-01-01

A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable pattern in the groundwater system. The model also provides a way for quantifying the significance of uncertainties in the tracer source term and transport parameters on the contaminant distribution in the groundwater system, an essential step in using the distribution of contaminants from local, point source atmospheric emissions to examine conceptual models of groundwater flow and transport

Critical review of hydraulic modeling on atmospheric heat dissipation

International Nuclear Information System (INIS)

Onishi, Y.; Brown, S.M.

1977-01-01

Objectives of this study were: to define the useful roles of hydraulic modeling in understanding the predicting atmospheric effects of heat dissipation systems; to assess the state-of-the-art of hydraulic modeling of atmospheric phenomena; to inventory potentially useful existing hydraulic modeling facilities both in the United States and abroad; and to scope hydraulic model studies to assist the assessment of atmospheric effects of nuclear energy centers

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

Calculation of atmospheric neutrino flux using the interaction model calibrated with atmospheric muon data

International Nuclear Information System (INIS)

Honda, M.; Kajita, T.; Kasahara, K.; Midorikawa, S.; Sanuki, T.

2007-01-01

Using the 'modified DPMJET-III' model explained in the previous paper [T. Sanuki et al., preceding Article, Phys. Rev. D 75, 043005 (2007).], we calculate the atmospheric neutrino flux. The calculation scheme is almost the same as HKKM04 [M. Honda, T. Kajita, K. Kasahara, and S. Midorikawa, Phys. Rev. D 70, 043008 (2004).], but the usage of the 'virtual detector' is improved to reduce the error due to it. Then we study the uncertainty of the calculated atmospheric neutrino flux summarizing the uncertainties of individual components of the simulation. The uncertainty of K-production in the interaction model is estimated using other interaction models: FLUKA'97 and FRITIOF 7.02, and modifying them so that they also reproduce the atmospheric muon flux data correctly. The uncertainties of the flux ratio and zenith angle dependence of the atmospheric neutrino flux are also studied

A NEW ASTROBIOLOGICAL MODEL OF THE ATMOSPHERE OF TITAN

International Nuclear Information System (INIS)

Willacy, K.; Allen, M.; Yung, Y.

2016-01-01

We present results of an investigation into the formation of nitrogen-bearing molecules in the atmosphere of Titan. We extend a previous model to cover the region below the tropopause, so the new model treats the atmosphere from Titan’s surface to an altitude of 1500 km. We consider the effects of condensation and sublimation using a continuous, numerically stable method. This is coupled with parameterized treatments of the sedimentation of the aerosols and their condensates, and the formation of haze particles. These processes affect the abundances of heavier species such as the nitrogen-bearing molecules, but have less effect on the abundances of lighter molecules. Removal of molecules to form aerosols also plays a role in determining the mixing ratios, particularly of HNC, HC 3 N, and HCN. We find good agreement with the recently detected mixing ratios of C 2 H 5 CN, with condensation playing an important role in determining the abundance of this molecule below 500 km. Of particular interest is the chemistry of acrylonitrile (C 2 H 3 CN) which has been suggested by Stevenson et al. as a molecule that could form biological membranes in an oxygen-deficient environment. With the inclusion of haze formation, we find good agreement of our model predictions of acrylonitrile with the available observations.

Ability of the CCSR-NIES atmospheric general circulation model in the stratosphere. Chapter 3

International Nuclear Information System (INIS)

Sugata, S.

1997-01-01

A quantitative evaluation of climate change such as global warming is impossible without a high-quality numerical model which describes the dynamics of the climate system and the circulation of energy and materials. The Center for Climate Research - National Institute for Environmental Studies (CCSR-NIES) atmospheric general circulation model (hereafter, GCM for a general circulation model) has been developed to obtain such a high-quality model. The emphasis of the development has been laid on the troposphere and the lower stratosphere below about 30 km altitude. This is natural because human beings live on the Earth's surface and the condition of the lower atmosphere directly affects human life. However, the stratosphere and the upper atmosphere beyond it have recently been the focus even in investigations of climate change, because they are relevant to many issues which relate closely to tropospheric climate change, such as the ozone hole, material exchange between the stratosphere and the troposphere, and physical interaction between the stratosphere and troposphere. This study extended the region of the CCSR-NIES GCM to the lower mesosphere (about 70 km from the surface). This is our first attempt to investigate this GCM's climatology in the upper atmosphere, although some studies for QBO in the middle and lower stratosphere had been done with the GCM

Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: A multi-model linear feedback analysis

OpenAIRE

Roy Tilla; Bopp Laurent; Gehlen Marion; Schneider Birgitt; Cadule Patricia; Frölicher Thomas; Segschneider Jochen; Tijputra Jerry; Heinze Christoph; Joos Fortunat

2011-01-01

The increase in atmospheric CO2 over this century depends on the evolution of the oceanic air–sea CO2 uptake which will be driven by the combined response to rising atmospheric CO2 itself and climate change. Here the future oceanic CO2 uptake is simulated using an ensemble of coupled climate–carbon cycle models. The models are driven by CO2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high emission scenario. A linear feedback analysis successfully sep...

Regional Precipitation Forecast with Atmospheric InfraRed Sounder (AIRS) Profile Assimilation

Science.gov (United States)

Chou, S.-H.; Zavodsky, B. T.; Jedloved, G. J.

2010-01-01

Advanced technology in hyperspectral sensors such as the Atmospheric InfraRed Sounder (AIRS; Aumann et al. 2003) on NASA's polar orbiting Aqua satellite retrieve higher vertical resolution thermodynamic profiles than their predecessors due to increased spectral resolution. Although these capabilities do not replace the robust vertical resolution provided by radiosondes, they can serve as a complement to radiosondes in both space and time. These retrieved soundings can have a significant impact on weather forecasts if properly assimilated into prediction models. Several recent studies have evaluated the performance of specific operational weather forecast models when AIRS data are included in the assimilation process. LeMarshall et al. (2006) concluded that AIRS radiances significantly improved 500 hPa anomaly correlations in medium-range forecasts of the Global Forecast System (GFS) model. McCarty et al. (2009) demonstrated similar forecast improvement in 0-48 hour forecasts in an offline version of the operational North American Mesoscale (NAM) model when AIRS radiances were assimilated at the regional scale. Reale et al. (2008) showed improvements to Northern Hemisphere 500 hPa height anomaly correlations in NASA's Goddard Earth Observing System Model, Version 5 (GEOS-5) global system with the inclusion of partly cloudy AIRS temperature profiles. Singh et al. (2008) assimilated AIRS temperature and moisture profiles into a regional modeling system for a study of a heavy rainfall event during the summer monsoon season in Mumbai, India. This paper describes an approach to assimilate AIRS temperature and moisture profiles into a regional configuration of the Advanced Research Weather Research and Forecasting (WRF-ARW) model using its three-dimensional variational (3DVAR) assimilation system (WRF-Var; Barker et al. 2004). Section 2 describes the AIRS instrument and how the quality indicators are used to intelligently select the highest-quality data for assimilation

Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation in the mid-troposphere – Part 1: 2-D modeling in mean atmosphere

Directory of Open Access Journals (Sweden)

J. Ma

2010-08-01

Full Text Available In the first part of this study for revisiting the cold condensation effect on global distribution of semi-volatile organic chemicals (SVOCs, the atmospheric transport of SVOCs to the Arctic in the mid-troposphere in a mean meridional atmospheric circulation over the Northern Hemisphere was simulated by a two-dimensional (2-D atmospheric transport model. Results show that under the mean meridional atmospheric circulation the long-range atmospheric transport of SVOCs from warm latitudes to the Arctic occurs primarily in the mid-troposphere. Although major sources are in low and mid-latitude soils, the modeled air concentration of SVOCs in the mid-troposphere is of the same order as or higher than that near the surface, demonstrating that the mid-troposphere is an important pathway and reservoir of SVOCs. The cold condensation of the chemicals is also likely to take place in the mid-troposphere over a source region of SVOCs in warm low latitudes through interacting with clouds. We demonstrate that the temperature dependent vapour pressure and atmospheric degradation rate of SVOCs exhibit similarities between lower atmosphere over the Arctic and the mid-troposphere over a tropical region. Frequent occurrence of atmospheric ascending motion and convection over warm latitudes carry the chemicals to a higher altitude where some of these chemicals may partition onto solid or aqueous phase through interaction with atmospheric aerosols, cloud water droplets and ice particles, and become more persistent at lower temperatures. Stronger winds in the mid-troposphere then convey solid and aqueous phase chemicals to the Arctic where they sink by large-scale descending motion and wet deposition. Using calculated water droplet-air partitioning coefficient of several persistent organic semi-volatile chemicals under a mean air temperature profile from the equator to the North Pole we propose that clouds are likely important sorbing media for SVOCs and pathway of

Verification of atmospheric diffusion models with data of atmospheric diffusion experiments

International Nuclear Information System (INIS)

Hato, Shinji; Homma, Toshimitsu

2009-02-01

The atmospheric diffusion experiments were implemented by Japan Atomic Energy Research Institute (JAERI) around Mount Tsukuba in 1989 and 1990, and the tracer gas concentration were monitored. In this study, the Gauss Plume Model and RAMS/HYPACT that are meteorological forecast code and atmospheric diffusion code with detailed physical law are made a comparison between monitored concentration. In conclusion, the Gauss Plume Model is better than RAM/HYPACT even complex topography if the estimation is around tens of kilometer form release point and the change in weather is constant for short time. This reason is difference of wind between RAMS and observation. (author)

Estimating the Greenland ice sheet surface mass balance contribution to future sea level rise using the regional atmospheric climate model MAR

Directory of Open Access Journals (Sweden)

X. Fettweis

2013-03-01

Full Text Available To estimate the sea level rise (SLR originating from changes in surface mass balance (SMB of the Greenland ice sheet (GrIS, we present 21st century climate projections obtained with the regional climate model MAR (Modèle Atmosphérique Régional, forced by output of three CMIP5 (Coupled Model Intercomparison Project Phase 5 general circulation models (GCMs. Our results indicate that in a warmer climate, mass gain from increased winter snowfall over the GrIS does not compensate mass loss through increased meltwater run-off in summer. Despite the large spread in the projected near-surface warming, all the MAR projections show similar non-linear increase of GrIS surface melt volume because no change is projected in the general atmospheric circulation over Greenland. By coarsely estimating the GrIS SMB changes from GCM output, we show that the uncertainty from the GCM-based forcing represents about half of the projected SMB changes. In 2100, the CMIP5 ensemble mean projects a GrIS SMB decrease equivalent to a mean SLR of +4 ± 2 cm and +9 ± 4 cm for the RCP (Representative Concentration Pathways 4.5 and RCP 8.5 scenarios respectively. These estimates do not consider the positive melt–elevation feedback, although sensitivity experiments using perturbed ice sheet topographies consistent with the projected SMB changes demonstrate that this is a significant feedback, and highlight the importance of coupling regional climate models to an ice sheet model. Such a coupling will allow the assessment of future response of both surface processes and ice-dynamic changes to rising temperatures, as well as their mutual feedbacks.

ARTEAM - Advanced ray tracing with earth atmospheric models

NARCIS (Netherlands)

Kunz, G.J.; Moerman, M.M.; Eijk, A.M.J. van

2002-01-01

The Advanced Ray Tracing with Earth Atmospheric Models (ARTEAM) aims at a description of the electro-optical propagation environment in the marine atmospheric surface layer. For given meteorological conditions, the model evaluates height- and range-resolved transmission losses, refraction and

Model for Atmospheric Propagation of Spatially Combined Laser Beams

Science.gov (United States)

2016-09-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS MODEL FOR ATMOSPHERIC PROPAGATION OF SPATIALLY COMBINED LASER BEAMS by Kum Leong Lee September...MODEL FOR ATMOSPHERIC PROPAGATION OF SPATIALLY COMBINED LASER BEAMS 5. FUNDING NUMBERS 6. AUTHOR(S) Kum Leong Lee 7. PERFORMING ORGANIZATION NAME(S) AND...BLANK ii Approved for public release. Distribution is unlimited. MODEL FOR ATMOSPHERIC PROPAGATION OF SPATIALLY COMBINED LASER BEAMS Kum Leong Lee

Evaluating 20th Century precipitation characteristics between multi-scale atmospheric models with different land-atmosphere coupling

Science.gov (United States)

Phillips, M.; Denning, A. S.; Randall, D. A.; Branson, M.

2016-12-01

Multi-scale models of the atmosphere provide an opportunity to investigate processes that are unresolved by traditional Global Climate Models while at the same time remaining viable in terms of computational resources for climate-length time scales. The MMF represents a shift away from large horizontal grid spacing in traditional GCMs that leads to overabundant light precipitation and lack of heavy events, toward a model where precipitation intensity is allowed to vary over a much wider range of values. Resolving atmospheric motions on the scale of 4 km makes it possible to recover features of precipitation, such as intense downpours, that were previously only obtained by computationally expensive regional simulations. These heavy precipitation events may have little impact on large-scale moisture and energy budgets, but are outstanding in terms of interaction with the land surface and potential impact on human life. Three versions of the Community Earth System Model were used in this study; the standard CESM, the multi-scale `Super-Parameterized' CESM where large-scale parameterizations have been replaced with a 2D cloud-permitting model, and a multi-instance land version of the SP-CESM where each column of the 2D CRM is allowed to interact with an individual land unit. These simulations were carried out using prescribed Sea Surface Temperatures for the period from 1979-2006 with daily precipitation saved for all 28 years. Comparisons of the statistical properties of precipitation between model architectures and against observations from rain gauges were made, with specific focus on detection and evaluation of extreme precipitation events.

Regional scale variations of atmospheric CO2 and CH4 from satellite observation

International Nuclear Information System (INIS)

Ru, F; Lei, L; Guan, X; Bu, R; Qi, J

2014-01-01

To identify the sources, sinks and changes of atmospheric CO 2 and CH 4 , this study investigates the spatio-temporal changes of atmospheric CO 2 and CH 4 concentration on the regional scale by the satellite observations. In this paper, choosing the land region of China as the study area, we investigate the spatio-temporal changes of atmospheric CO 2 and CH 4 concentrations using the data of the CO 2 dry air mixing ratio (XCO 2 ), and the CH 4 dry air mixing ratio (XCH 4 ), retrieved by the Greenhouse Gases Observing Satellite (GOSAT) from Jan. 2010 to Dec. 2012. The results show that (1) both XCO 2 and XCH 4 show higher concentrations in southeastern regions than that in the northwestern, and tend to yearly increasing from 2010 to 2013; (2) XCO 2 shows obvious seasonal change with higher values in the spring than that in summer. The seasonal peak-to-peak amplitude is 8 ppm and the annual growth is about 2 ppm. XCH 4 , however, does not show a seasonal change; (3) With regard to different land-use backgrounds, XCO 2 shows larger concentrations over the areas of urban agglomeration than that over the grasslands and deserts, and XCH 4 shows lower concentrations over deserts than that over the Yangtze River Delta region and Sichuan Basin

An investigation of tropical Atlantic bias in a high-resolution coupled regional climate model

Energy Technology Data Exchange (ETDEWEB)

Patricola, Christina M.; Saravanan, R.; Hsieh, Jen-Shan [Texas A and M University, Department of Atmospheric Sciences, College Station, TX (United States); Li, Mingkui; Xu, Zhao [Texas A and M University, Department of Oceanography, College Station, TX (United States); Ocean University of China, Key Laboratory of Physical Oceanography of Ministry of Education, Qingdao (China); Chang, Ping [Texas A and M University, Department of Oceanography, College Station, TX (United States); Ocean University of China, Key Laboratory of Physical Oceanography of Ministry of Education, Qingdao (China); Second Institute of Oceanography, State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou, Zhejiang (China)

2012-11-15

Coupled atmosphere-ocean general circulation models (AOGCMs) commonly fail to simulate the eastern equatorial Atlantic boreal summer cold tongue and produce a westerly equatorial trade wind bias. This tropical Atlantic bias problem is investigated with a high-resolution (27-km atmosphere represented by the Weather Research and Forecasting Model, 9-km ocean represented by the Regional Ocean Modeling System) coupled regional climate model. Uncoupled atmospheric simulations test climate sensitivity to cumulus, land-surface, planetary boundary layer, microphysics, and radiation parameterizations and reveal that the radiation scheme has a pronounced impact in the tropical Atlantic. The CAM radiation simulates a dry precipitation (up to -90%) and cold land-surface temperature (up to -8 K) bias over the Amazon related to an over-representation of low-level clouds and almost basin-wide westerly trade wind bias. The Rapid Radiative Transfer Model and Goddard radiation simulates doubled Amazon and Congo Basin precipitation rates and a weak eastern Atlantic trade wind bias. Season-long high-resolution coupled regional model experiments indicate that the initiation of the warm eastern equatorial Atlantic sea surface temperature (SST) bias is more sensitive to the local rather than basin-wide trade wind bias and to a wet Congo Basin instead of dry Amazon - which differs from AOGCM simulations. Comparisons between coupled and uncoupled simulations suggest a regional Bjerknes feedback confined to the eastern equatorial Atlantic amplifies the initial SST, wind, and deepened thermocline bias, while barrier layer feedbacks are relatively unimportant. The SST bias in some CRCM simulations resembles the typical AOGCM bias indicating that increasing resolution is unlikely a simple solution to this problem. (orig.)

Atmospheric statistical dynamic models. Model performance: the Lawrence Livermore Laboratoy Zonal Atmospheric Model

International Nuclear Information System (INIS)

Potter, G.L.; Ellsaesser, H.W.; MacCracken, M.C.; Luther, F.M.

1978-06-01

Results from the zonal model indicate quite reasonable agreement with observation in terms of the parameters and processes that influence the radiation and energy balance calculations. The model produces zonal statistics similar to those from general circulation models, and has also been shown to produce similar responses in sensitivity studies. Further studies of model performance are planned, including: comparison with July data; comparison of temperature and moisture transport and wind fields for winter and summer months; and a tabulation of atmospheric energetics. Based on these preliminary performance studies, however, it appears that the zonal model can be used in conjunction with more complex models to help unravel the problems of understanding the processes governing present climate and climate change. As can be seen in the subsequent paper on model sensitivity studies, in addition to reduced cost of computation, the zonal model facilitates analysis of feedback mechanisms and simplifies analysis of the interactions between processes

Future projections of the surface heat and water budgets of the Mediterranean Sea in an ensemble of coupled atmosphere-ocean regional climate models

Energy Technology Data Exchange (ETDEWEB)

Dubois, C.; Somot, S.; Deque, M.; Sevault, F. [CNRM-GAME, Meteo-France, CNRS, Toulouse (France); Calmanti, S.; Carillo, A.; Dell' Aquilla, A.; Sannino, G. [ENEA, Rome (Italy); Elizalde, A.; Jacob, D. [Max Planck Institute for Meteorology, Hamburg (Germany); Gualdi, S.; Oddo, P.; Scoccimarro, E. [INGV, Bologna (Italy); L' Heveder, B.; Li, L. [Laboratoire de Meteorologie Dynamique, Paris (France)

2012-10-15

Within the CIRCE project ''Climate change and Impact Research: the Mediterranean Environment'', an ensemble of high resolution coupled atmosphere-ocean regional climate models (AORCMs) are used to simulate the Mediterranean climate for the period 1950-2050. For the first time, realistic net surface air-sea fluxes are obtained. The sea surface temperature (SST) variability is consistent with the atmospheric forcing above it and oceanic constraints. The surface fluxes respond to external forcing under a warming climate and show an equivalent trend in all models. This study focuses on the present day and on the evolution of the heat and water budget over the Mediterranean Sea under the SRES-A1B scenario. On the contrary to previous studies, the net total heat budget is negative over the present period in all AORCMs and satisfies the heat closure budget controlled by a net positive heat gain at the strait of Gibraltar in the present climate. Under climate change scenario, some models predict a warming of the Mediterranean Sea from the ocean surface (positive net heat flux) in addition to the positive flux at the strait of Gibraltar for the 2021-2050 period. The shortwave and latent flux are increasing and the longwave and sensible fluxes are decreasing compared to the 1961-1990 period due to a reduction of the cloud cover and an increase in greenhouse gases (GHGs) and SSTs over the 2021-2050 period. The AORCMs provide a good estimates of the water budget with a drying of the region during the twenty-first century. For the ensemble mean, he decrease in precipitation and runoff is about 10 and 15% respectively and the increase in evaporation is much weaker, about 2% compared to the 1961-1990 period which confirm results obtained in recent studies. Despite a clear consistency in the trends and results between the models, this study also underlines important differences in the model set-ups, methodology and choices of some physical parameters inducing

Lichens as indicators of the atmosphere state in the oil exploration district of Tomsk Region

Science.gov (United States)

Bolshunova, Tatiana; Ivan, Podkozlin

2013-04-01

Lichens are widespread in the vegetative cover of West Siberia, particularly in the north. They play an important role in the migration and transformation of chemical pollutants. Lichens lack waxy cuticles and are largely dependent on the atmosphere for their water and nutrient uptake. Lichens are not only studied and used as indicators, but also as accumulators, e.g. for trace and heavy metals. In fact, lichens are known for their ability to accumulate airborne substances to concentrations far greater those in the atmosphere, and the element contents of lichen thalli proved to be directly correlated with environmental levels. Monitoring of the atmosphere pollution using lichens is more efficient than that using snow cover. Because of the long lichen life it is possible to obtain persistent mean characteristics of the ecosystems state. Epiphytic lichens, growing on tree stems are more appropriate to use than that which grow on soil. Epiphytic lichens are more sensitive to changes of the chemical composition of the atmosphere. Pollutants penetrate in the lichen thalli from the atmosphere together with precipitations and dust. Moreover the precipitations are saturated with pollutants when going through crowns of trees and trickling down the steams and branches. Lichen studies are especially important in territories subjected to excessive human activity. Because a great part of Tomsk region (West Siberia, Russia) is the territory of the oil-field exploration, there the atmosphere monitoring is a necessary part of the whole environmental monitoring. The aim of this investigation is the estimation of the influence of oil exploration industry in Tomsk region on the atmosphere by means of the study of epiphytic lichens. Lichen samples were collected in August and September 2010-2011. Sampling net included seven areas distributed inside the oil-exploration districts of Tomsk region. In total 27 samples were collected. In these samples 53 chemical elements were detected by

Accident consequence assessments with different atmospheric dispersion models

International Nuclear Information System (INIS)

Panitz, H.J.

1989-11-01

An essential aim of the improvements of the new program system UFOMOD for Accident Consequence Assessments (ACAs) was to substitute the straight-line Gaussian plume model conventionally used in ACA models by more realistic atmospheric dispersion models. To identify improved models which can be applied in ACA codes and to quantify the implications of different dispersion models on the results of an ACA, probabilistic comparative calculations with different atmospheric dispersion models have been performed. The study showed that there are trajectory models available which can be applied in ACAs and that they provide more realistic results of ACAs than straight-line Gaussian models. This led to a completely novel concept of atmospheric dispersion modelling in which two different distance ranges of validity are distinguished: the near range of some ten kilometres distance and the adjacent far range which are assigned to respective trajectory models. (orig.) [de

Key features of the IPSL ocean atmosphere model and its sensitivity to atmospheric resolution

Energy Technology Data Exchange (ETDEWEB)

Marti, Olivier; Braconnot, P.; Bellier, J.; Brockmann, P.; Caubel, A.; Noblet, N. de; Friedlingstein, P.; Idelkadi, A.; Kageyama, M. [Unite Mixte CEA-CNRS-UVSQ, IPSL/LSCE, Gif-sur-Yvette Cedex (France); Dufresne, J.L.; Bony, S.; Codron, F.; Fairhead, L.; Grandpeix, J.Y.; Hourdin, F.; Musat, I. [Unite Mixte CNRS-Ecole Polytechnique-ENS-UPCM, IPSL/LMD, Paris Cedex 05 (France); Benshila, R.; Guilyardi, E.; Levy, C.; Madec, G.; Mignot, J.; Talandier, C. [unite mixte CNRS-IRD-UPMC, IPLS/LOCEAN, Paris Cedex 05 (France); Cadule, P.; Denvil, S.; Foujols, M.A. [Institut Pierre Simon Laplace des Sciences de l' Environnement (IPSL), Paris Cedex 05 (France); Fichefet, T.; Goosse, H. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); Krinner, G. [Unite mixte CNRS-UJF Grenoble, LGGE, BP96, Saint-Martin-d' Heres (France); Swingedouw, D. [CNRS/CERFACS, Toulouse (France)

2010-01-15

This paper presents the major characteristics of the Institut Pierre Simon Laplace (IPSL) coupled ocean-atmosphere general circulation model. The model components and the coupling methodology are described, as well as the main characteristics of the climatology and interannual variability. The model results of the standard version used for IPCC climate projections, and for intercomparison projects like the Paleoclimate Modeling Intercomparison Project (PMIP 2) are compared to those with a higher resolution in the atmosphere. A focus on the North Atlantic and on the tropics is used to address the impact of the atmosphere resolution on processes and feedbacks. In the North Atlantic, the resolution change leads to an improved representation of the storm-tracks and the North Atlantic oscillation. The better representation of the wind structure increases the northward salt transports, the deep-water formation and the Atlantic meridional overturning circulation. In the tropics, the ocean-atmosphere dynamical coupling, or Bjerknes feedback, improves with the resolution. The amplitude of ENSO (El Nino-Southern oscillation) consequently increases, as the damping processes are left unchanged. (orig.)

Meteorological Modeling Using the WRF-ARW Model for Grand Bay Intensive Studies of Atmospheric Mercury

Directory of Open Access Journals (Sweden)

Fong Ngan

2015-02-01

Full Text Available Measurements at the Grand Bay National Estuarine Research Reserve support a range of research activities aimed at improving the understanding of the atmospheric fate and transport of mercury. Routine monitoring was enhanced by two intensive measurement periods conducted at the site in summer 2010 and spring 2011. Detailed meteorological data are required to properly represent the weather conditions, to determine the transport and dispersion of plumes and to understand the wet and dry deposition of mercury. To describe the mesoscale features that might influence future plume calculations for mercury episodes during the Grand Bay Intensive campaigns, fine-resolution meteorological simulations using the Weather Research and Forecasting (WRF model were conducted with various initialization and nudging configurations. The WRF simulations with nudging generated reasonable results in comparison with conventional observations in the region and measurements obtained at the Grand Bay site, including surface and sounding data. The grid nudging, together with observational nudging, had a positive effect on wind prediction. However, the nudging of mass fields (temperature and moisture led to overestimates of precipitation, which may introduce significant inaccuracies if the data were to be used for subsequent atmospheric mercury modeling. The regional flow prediction was also influenced by the reanalysis data used to initialize the WRF simulations. Even with observational nudging, the summer case simulation results in the fine resolution domain inherited features of the reanalysis data, resulting in different regional wind patterns. By contrast, the spring intensive period showed less influence from the reanalysis data.

Modeling of atmospheric dispersion of radionuclides

International Nuclear Information System (INIS)

Baklouti, Nada

2010-01-01

This work is a prediction of atmospheric dispersion of radionuclide from a chronic rejection of the nuclear power generating plant that can be located in one of the Tunisian sites: Skhira or Bizerte. Also it contains a study of acute rejection 'Chernobyl accident' which was the reference for the validation of GENII the code of modeling of atmospheric dispersion.

Propagation of cosmic rays through the atmosphere in the quark-gluon strings model

Science.gov (United States)

Erlykin, A. D.; Krutikova, N. P.; Shabelski, Y. M.

1985-01-01

The quark-gluon strings model succeeds in the description of multiple hadron production in the central rapidity region of nucleon-nucleon interctions. This model was developed for hadron-nucleus interactions and used for calculation of the cosmic ray propagation through the atmosphere. It is shown that at energies 10 to the 11th power to the 12th power eV, this model gives a satisfactory description of experimental data. But with the increase of the energy up to approximately 10 to the 14th power eV, results of calculations and of experiments begin to differ and this difference rises with the energy. It may indicate that the scaling violation in the fragmentation region of inclusive spectra for hadron-nucleus interactions is stronger than in the quark-gluon strings model.

Interlaboratory model comparisons of atmospheric concentrations with and without deposition

International Nuclear Information System (INIS)

Kern, C.D.; Cooper, R.E.

1978-01-01

To calculate the dose to the regional and U.S. populations, the pollutant concentration both with and without deposition and the amount of material deposited on the ground and watersheds around such a facility must be known. The following report (Article 50) of this document contains some initial estimates of population exposure from atmospheric effluents. The expertise of laboratories supported by U.S. Department of Energy funds ensures that the latest methods and data are available. Lawrence Livermore Laboratory (LLL) performed regional calculations (out to distances of the order of 200 km from a hypothetical fuel reprocessing plant). The Air Resources Laboratory (ARL) of the National Oceanic and Atmospheric Administration (NOAA), and Battelle Pacific Northwest Laboratories (PNL) performed U.S. scale calculations, and ARL also did the global calculations. Data from a winter and summer period were used to make comparisons of calculations by LLL, ARL, and PNL to determine which model should be used for the final calculations and to determine if a 200-km square area centered on the site would be large enough for dose calculations via the water and food pathways

Atmosphere-soil-vegetation model including CO2 exchange processes: SOLVEG2

International Nuclear Information System (INIS)

Nagai, Haruyasu

2004-11-01

A new atmosphere-soil-vegetation model named SOLVEG2 (SOLVEG version 2) was developed to study the heat, water, and CO 2 exchanges between the atmosphere and land-surface. The model consists of one-dimensional multilayer sub-models for the atmosphere, soil, and vegetation. It also includes sophisticated processes for solar and long-wave radiation transmission in vegetation canopy and CO 2 exchanges among the atmosphere, soil, and vegetation. Although the model usually simulates only vertical variation of variables in the surface-layer atmosphere, soil, and vegetation canopy by using meteorological data as top boundary conditions, it can be used by coupling with a three-dimensional atmosphere model. In this paper, details of SOLVEG2, which includes the function of coupling with atmosphere model MM5, are described. (author)

Atlantic multidecadal oceanic variability and its influence on the atmosphere in a climate model

Energy Technology Data Exchange (ETDEWEB)

Msadek, Rym; Frankignoul, Claude [Universite Pierre et Marie Curie, Paris 6, LOCEAN/IPSL, Paris (France)

2009-07-15

The mechanisms controlling the decadal to multidecadal variability of the Atlantic Meridional Overturning Circulation (MOC) and its influence on the atmosphere are investigated using a control simulation with the IPSL-CM4 climate model. The multidecadal fluctuations of the MOC are mostly driven by deep convection in the subpolar gyre, which occurs south of Iceland in the model. The latter is primarily influenced by the anomalous advection of salinity due to changes in the East Atlantic Pattern (EAP), which is the second mode of atmospheric variability in the North Atlantic region. The North Atlantic Oscillation is the dominant mode, but it plays a secondary role in the MOC fluctuations. During summer, the MOC variability is shown to have a significant impact on the atmosphere in the North Atlantic-European sector. The MOC influence is due to an interhemispheric sea surface temperature (SST) anomaly with opposite signs in the two hemispheres but largest amplitude in the northern one. The SST pattern driven by the MOC mostly resembles the model Atlantic Multidecadal Oscillation (AMO) and bears some similarity with the observed one. It is shown that the AMO reflects both the MOC influence and the local atmospheric forcing. Hence, the MOC influence on climate is best detected using lagged relations between climatic fields. The atmospheric response resembles the EAP, in a phase that might induce a weak positive feedback on the MOC. (orig.)

Extracting Urban Morphology for Atmospheric Modeling from Multispectral and SAR Satellite Imagery

Science.gov (United States)

Wittke, S.; Karila, K.; Puttonen, E.; Hellsten, A.; Auvinen, M.; Karjalainen, M.

2017-05-01

This paper presents an approach designed to derive an urban morphology map from satellite data while aiming to minimize the cost of data and user interference. The approach will help to provide updates to the current morphological databases around the world. The proposed urban morphology maps consist of two layers: 1) Digital Elevation Model (DEM) and 2) land cover map. Sentinel-2 data was used to create a land cover map, which was realized through image classification using optical range indices calculated from image data. For the purpose of atmospheric modeling, the most important classes are water and vegetation areas. The rest of the area includes bare soil and built-up areas among others, and they were merged into one class in the end. The classification result was validated with ground truth data collected both from field measurements and aerial imagery. The overall classification accuracy for the three classes is 91 %. TanDEM-X data was processed into two DEMs with different grid sizes using interferometric SAR processing. The resulting DEM has a RMSE of 3.2 meters compared to a high resolution DEM, which was estimated through 20 control points in flat areas. Comparing the derived DEM with the ground truth DEM from airborne LIDAR data, it can be seen that the street canyons, that are of high importance for urban atmospheric modeling are not detectable in the TanDEM-X DEM. However, the derived DEM is suitable for a class of urban atmospheric models. Based on the numerical modeling needs for regional atmospheric pollutant dispersion studies, the generated files enable the extraction of relevant parametrizations, such as Urban Canopy Parameters (UCP).

EXTRACTING URBAN MORPHOLOGY FOR ATMOSPHERIC MODELING FROM MULTISPECTRAL AND SAR SATELLITE IMAGERY

Directory of Open Access Journals (Sweden)

S. Wittke

2017-05-01

Full Text Available This paper presents an approach designed to derive an urban morphology map from satellite data while aiming to minimize the cost of data and user interference. The approach will help to provide updates to the current morphological databases around the world. The proposed urban morphology maps consist of two layers: 1 Digital Elevation Model (DEM and 2 land cover map. Sentinel-2 data was used to create a land cover map, which was realized through image classification using optical range indices calculated from image data. For the purpose of atmospheric modeling, the most important classes are water and vegetation areas. The rest of the area includes bare soil and built-up areas among others, and they were merged into one class in the end. The classification result was validated with ground truth data collected both from field measurements and aerial imagery. The overall classification accuracy for the three classes is 91 %. TanDEM-X data was processed into two DEMs with different grid sizes using interferometric SAR processing. The resulting DEM has a RMSE of 3.2 meters compared to a high resolution DEM, which was estimated through 20 control points in flat areas. Comparing the derived DEM with the ground truth DEM from airborne LIDAR data, it can be seen that the street canyons, that are of high importance for urban atmospheric modeling are not detectable in the TanDEM-X DEM. However, the derived DEM is suitable for a class of urban atmospheric models. Based on the numerical modeling needs for regional atmospheric pollutant dispersion studies, the generated files enable the extraction of relevant parametrizations, such as Urban Canopy Parameters (UCP.

Assessment of model estimates of land-atmosphere CO2 exchange across northern Eurasia

Science.gov (United States)

Rawlins, M.A.; McGuire, A.D.; Kimball, J.S.; Dass, P.; Lawrence, D.; Burke, E.; Chen, X.; Delire, C.; Koven, C.; MacDougall, A.; Peng, S.; Rinke, A.; Saito, K.; Zhang, W.; Alkama, R.; Bohn, T. J.; Ciais, P.; Decharme, B.; Gouttevin, I.; Hajima, T.; Ji, D.; Krinner, G.; Lettenmaier, D.P.; Miller, P.; Moore, J.C.; Smith, B.; Sueyoshi, T.

2015-01-01

A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960–2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m−2 yr−2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960–1969 vs. 2000–2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model

On Verifying Currents and Other Features in the Hawaiian Islands Region Using Fully Coupled Ocean/Atmosphere Mesoscale Prediction System Compared to Global Ocean Model and Ocean Observations

Science.gov (United States)

Jessen, P. G.; Chen, S.

2014-12-01

This poster introduces and evaluates features concerning the Hawaii, USA region using the U.S. Navy's fully Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS-OS™) coupled to the Navy Coastal Ocean Model (NCOM). It also outlines some challenges in verifying ocean currents in the open ocean. The system is evaluated using in situ ocean data and initial forcing fields from the operational global Hybrid Coordinate Ocean Model (HYCOM). Verification shows difficulties in modelling downstream currents off the Hawaiian islands (Hawaii's wake). Comparing HYCOM to NCOM current fields show some displacement of small features such as eddies. Generally, there is fair agreement from HYCOM to NCOM in salinity and temperature fields. There is good agreement in SSH fields.

Organochlorine pesticides in the atmosphere of Guangzhou and Hong Kong: Regional sources and long-range atmospheric transport

Science.gov (United States)

Li, Jun; Zhang, Gan; Guo, Lingli; Xu, Weihai; Li, Xiangdong; Lee, Celine S. L.; Ding, Aijun; Wang, Tao

Organochlorine pesticides (OCPs) were measured in the atmosphere over the period of December 2003-December 2004 at four sampling sites in Guangzhou and Hong Kong. Gas phase and particle phase concentrations of 8 OCP species, including trans-chlordane ( t-CHL), cis-chlordane ( c-CHL), p, p'-DDT, p, p'-DDE, o, p'-DDT, α-endosulfan, α- and γ-hexachlorocyclohexane (HCH), were studied. OCPs were found predominantly in the gas phase in all seasons. t-CHL, c-CHL, o, p'-DDT, p, p'-DDT and α-endosulfan had significantly ( pGuangzhou could be attributed to the present usage of lindane and dicofol in the Pearl River Delta (PRD) region. The very high concentrations of p, p'-DDT and α-endosulfan were observed at all sampling sites. The results of 7 days air back trajectory analysis indicated that the unusual high p, p'-DDT levels in summer in both cities could be related to the seasonal usage of DDT containing antifouling paints for fishing ships in the upwind seaports of the region. The high concentrations of α-endosulfan in winter in the study area suggested an atmospheric transport by the winter monsoon from the East China, where endosulfan is being used as insecticide in cotton fields. The consistency of the seasonal variation of concentrations and isomeric ratios of DDTs and α-endosulfan with the alternation of winter monsoon and summer monsoon suggested that the Asian monsoon plays an important role in the long-range atmospheric transport of OCPs.

Model for Simulation Atmospheric Turbulence

DEFF Research Database (Denmark)

Lundtang Petersen, Erik

1976-01-01

A method that produces realistic simulations of atmospheric turbulence is developed and analyzed. The procedure makes use of a generalized spectral analysis, often called a proper orthogonal decomposition or the Karhunen-Loève expansion. A set of criteria, emphasizing a realistic appearance...... eigenfunctions and estimates of the distributions of the corresponding expansion coefficients. The simulation method utilizes the eigenfunction expansion procedure to produce preliminary time histories of the three velocity components simultaneously. As a final step, a spectral shaping procedure is then applied....... The method is unique in modeling the three velocity components simultaneously, and it is found that important cross-statistical features are reasonably well-behaved. It is concluded that the model provides a practical, operational simulator of atmospheric turbulence....

Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

Science.gov (United States)

Liu, Lei; Zhang, Xiuying; Xu, Wen; Liu, Xuejun; Li, Yi; Lu, Xuehe; Zhang, Yuehan; Zhang, Wuting

2017-08-01

China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen (Nr). Atmospheric ammonia (NH3) and nitrogen dioxide (NO2) are the most important precursors for Nr compounds (including N2O5, HNO3, HONO and particulate NO3- and NH4+) in the atmosphere. Understanding the changes in NH3 and NO2 has important implications for the regulation of anthropogenic Nr emissions and is a requirement for assessing the consequence of environmental impacts. We conducted the temporal trend analysis of atmospheric NH3 and NO2 on a national scale since 1980 based on emission data (during 1980-2010), satellite observation (for NH3 since 2008 and for NO2 since 2005) and atmospheric chemistry transport modeling (during 2008-2015).Based on the emission data, during 1980-2010, significant continuous increasing trends in both NH3 and NOx were observed in REAS (Regional Emission inventory in Asia, for NH3 0.17 and for NOx 0.16 kg N ha-1 yr-2) and EDGAR (Emissions Database for Global Atmospheric Research, for NH3 0.24 and for NOx 0.17 kg N ha-1 yr-2) over China. Based on the satellite data and atmospheric chemistry transport model (CTM) MOZART-4 (Model for Ozone and Related chemical Tracers, version 4), the NO2 columns over China increased significantly from 2005 to 2011 and then decreased significantly from 2011 to 2015; the satellite-retrieved NH3 columns from 2008 to 2014 increased at a rate of 2.37 % yr-1. The decrease in NO2 columns since 2011 may result from more stringent strategies taken to control NOx emissions during the 12th Five Year Plan, while no control policy has focused on NH3 emissions. Our findings provided an overall insight into the temporal trends of both NO2 and NH3 since 1980 based on emission data, satellite observations and atmospheric transport modeling. These findings can provide a scientific background for policy makers that are attempting to control atmospheric pollution in China. Moreover, the multiple datasets

NASA's Upper Atmosphere Research Program (UARP) and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1997-1999

Science.gov (United States)

Kurylo, M. J.; DeCola, P. L.; Kaye, J. A.

2000-01-01

Under the mandate contained in the FY 1976 NASA Authorization Act, the National Aeronautics and Space Administration (NASA) has developed and is implementing a comprehensive program of research, technology development, and monitoring of the Earth's upper atmosphere, with emphasis on the upper troposphere and stratosphere. This program aims at expanding our chemical and physical understanding to permit both the quantitative analysis of current perturbations as well as the assessment of possible future changes in this important region of our environment. It is carried out jointly by the Upper Atmosphere Research Program (UARP) and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP), both managed within the Research Division in the Office of Earth Science at NASA. Significant contributions to this effort have also been provided by the Atmospheric Effects of Aviation Project (AEAP) of NASA's Office of Aero-Space Technology. The long-term objectives of the present program are to perform research to: understand the physics, chemistry, and transport processes of the upper troposphere and the stratosphere and their control on the distribution of atmospheric chemical species such as ozone; assess possible perturbations to the composition of the atmosphere caused by human activities and natural phenomena (with a specific emphasis on trace gas geographical distributions, sources, and sinks and the role of trace gases in defining the chemical composition of the upper atmosphere); understand the processes affecting the distributions of radiatively active species in the atmosphere, and the importance of chemical-radiative-dynamical feedbacks on the meteorology and climatology of the stratosphere and troposphere; and understand ozone production, loss, and recovery in an atmosphere with increasing abundances of greenhouse gases. The current report is composed of two parts. Part 1 summarizes the objectives, status, and accomplishments of the research tasks supported

A review of operational, regional-scale, chemical weather forecasting models in Europe

Directory of Open Access Journals (Sweden)

J. Kukkonen

2012-01-01

Full Text Available Numerical models that combine weather forecasting and atmospheric chemistry are here referred to as chemical weather forecasting models. Eighteen operational chemical weather forecasting models on regional and continental scales in Europe are described and compared in this article. Topics discussed in this article include how weather forecasting and atmospheric chemistry models are integrated into chemical weather forecasting systems, how physical processes are incorporated into the models through parameterization schemes, how the model architecture affects the predicted variables, and how air chemistry and aerosol processes are formulated. In addition, we discuss sensitivity analysis and evaluation of the models, user operational requirements, such as model availability and documentation, and output availability and dissemination. In this manner, this article allows for the evaluation of the relative strengths and weaknesses of the various modelling systems and modelling approaches. Finally, this article highlights the most prominent gaps of knowledge for chemical weather forecasting models and suggests potential priorities for future research directions, for the following selected focus areas: emission inventories, the integration of numerical weather prediction and atmospheric chemical transport models, boundary conditions and nesting of models, data assimilation of the various chemical species, improved understanding and parameterization of physical processes, better evaluation of models against data and the construction of model ensembles.

Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

Science.gov (United States)

Murguia-Flores, Fabiola; Arndt, Sandra; Ganesan, Anita L.; Murray-Tortarolo, Guillermo; Hornibrook, Edward R. C.

2018-06-01

Soil bacteria known as methanotrophs are the sole biological sink for atmospheric methane (CH4), a potent greenhouse gas that is responsible for ˜ 20 % of the human-driven increase in radiative forcing since pre-industrial times. Soil methanotrophy is controlled by a plethora of factors, including temperature, soil texture, moisture and nitrogen content, resulting in spatially and temporally heterogeneous rates of soil methanotrophy. As a consequence, the exact magnitude of the global soil sink, as well as its temporal and spatial variability, remains poorly constrained. We developed a process-based model (Methanotrophy Model; MeMo v1.0) to simulate and quantify the uptake of atmospheric CH4 by soils at the global scale. MeMo builds on previous models by Ridgwell et al. (1999) and Curry (2007) by introducing several advances, including (1) a general analytical solution of the one-dimensional diffusion-reaction equation in porous media, (2) a refined representation of nitrogen inhibition on soil methanotrophy, (3) updated factors governing the influence of soil moisture and temperature on CH4 oxidation rates and (4) the ability to evaluate the impact of autochthonous soil CH4 sources on uptake of atmospheric CH4. We show that the improved structural and parametric representation of key drivers of soil methanotrophy in MeMo results in a better fit to observational data. A global simulation of soil methanotrophy for the period 1990-2009 using MeMo yielded an average annual sink of 33.5 ± 0.6 Tg CH4 yr-1. Warm and semi-arid regions (tropical deciduous forest and open shrubland) had the highest CH4 uptake rates of 602 and 518 mg CH4 m-2 yr-1, respectively. In these regions, favourable annual soil moisture content ( ˜ 20 % saturation) and low seasonal temperature variations (variations < ˜ 6 °C) provided optimal conditions for soil methanotrophy and soil-atmosphere gas exchange. In contrast to previous model analyses, but in agreement with recent observational data

Intraseasonal variability in the far-east pacific: investigation of the role of air-sea coupling in a regional coupled model

Energy Technology Data Exchange (ETDEWEB)

Small, R.J. [Naval Research Laboratory, Jacobs Technology, Stennis Space Center, MS (United States); University of Hawaii, International Pacific Research Center, POST 401, Honolulu, HI (United States); Xie, Shang-Ping [University of Hawaii, International Pacific Research Center, POST 401, Honolulu, HI (United States); University of Hawaii, Department of Meteorology, School of Ocean and Earth Science and Technology, Honolulu, HI (United States); Maloney, Eric D. [Colorado State University, Department of Atmospheric Science, Fort Collins, CO (United States); Szoeke, Simon P. de [Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR (United States); Miyama, Toru [Frontier Research for Global Change, Yokohama (Japan)

2011-03-15

Intraseasonal variability in the eastern Pacific warm pool in summer is studied, using a regional ocean-atmosphere model, a linear baroclinic model (LBM), and satellite observations. The atmospheric component of the model is forced by lateral boundary conditions from reanalysis data. The aim is to quantify the importance to atmospheric deep convection of local air-sea coupling. In particular, the effect of sea surface temperature (SST) anomalies on surface heat fluxes is examined. Intraseasonal (20-90 day) east Pacific warm-pool zonal wind and outgoing longwave radiation (OLR) variability in the regional coupled model are correlated at 0.8 and 0.6 with observations, respectively, significant at the 99% confidence level. The strength of the intraseasonal variability in the coupled model, as measured by the variance of outgoing longwave radiation, is close in magnitude to that observed, but with a maximum located about 10 further west. East Pacific warm pool intraseasonal convection and winds agree in phase with those from observations, suggesting that remote forcing at the boundaries associated with the Madden-Julian oscillation determines the phase of intraseasonal convection in the east Pacific warm pool. When the ocean model component is replaced by weekly reanalysis SST in an atmosphere-only experiment, there is a slight improvement in the location of the highest OLR variance. Further sensitivity experiments with the regional atmosphere-only model in which intraseasonal SST variability is removed indicate that convective variability has only a weak dependence on the SST variability, but a stronger dependence on the climatological mean SST distribution. A scaling analysis confirms that wind speed anomalies give a much larger contribution to the intraseasonal evaporation signal than SST anomalies, in both model and observations. A LBM is used to show that local feedbacks would serve to amplify intraseasonal convection and the large-scale circulation. Further

Interannual variability in the atmospheric CO2 rectification over a boreal forest region

Science.gov (United States)

Chen, Baozhang; Chen, Jing M.; Worthy, Douglas E. J.

2005-08-01

Ecosystem CO2 exchange with the atmosphere and the planetary boundary layer (PBL) dynamics are correlated diurnally and seasonally. The strength of this kind of covariation is quantified as the rectifier effect, and it affects the vertical gradient of CO2 and thus the global CO2 distribution pattern. An 11-year (1990-1996, 1999-2002), continuous CO2 record from Fraserdale, Ontario (49°52'29.9″N, 81°34'12.3″W), along with a coupled vertical diffusion scheme (VDS) and ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS), are used to investigate the interannual variability of the rectifier effect over a boreal forest region. The coupled model performed well (r2 = 0.70 and 0.87, at 40 m at hourly and daily time steps, respectively) in simulating CO2 vertical diffusion processes. The simulated annual atmospheric rectifier effect varies from 3.99 to 5.52 ppm, while the diurnal rectifying effect accounted for about a quarter of the annual total (22.8˜28.9%).The atmospheric rectification of CO2 is not simply influenced by terrestrial source and sink strengths, but by seasonal and diurnal variations in the land CO2 flux and their interaction with PBL dynamics. Air temperature and moisture are found to be the dominant climatic factors controlling the rectifier effect. The annual rectifier effect is highly correlated with annual mean temperature (r2 = 0.84), while annual mean air relative humidity can explain 51% of the interannual variation in rectification. Seasonal rectifier effect is also found to be more sensitive to climate variability than diurnal rectifier effect.

A NEW ASTROBIOLOGICAL MODEL OF THE ATMOSPHERE OF TITAN

Energy Technology Data Exchange (ETDEWEB)

Willacy, K. [MS 169-507, Caltech/Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Allen, M. [Caltech/Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Yung, Y., E-mail: Karen.Willacy@jpl.nasa.gov [Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125 (United States)

2016-10-01

We present results of an investigation into the formation of nitrogen-bearing molecules in the atmosphere of Titan. We extend a previous model to cover the region below the tropopause, so the new model treats the atmosphere from Titan’s surface to an altitude of 1500 km. We consider the effects of condensation and sublimation using a continuous, numerically stable method. This is coupled with parameterized treatments of the sedimentation of the aerosols and their condensates, and the formation of haze particles. These processes affect the abundances of heavier species such as the nitrogen-bearing molecules, but have less effect on the abundances of lighter molecules. Removal of molecules to form aerosols also plays a role in determining the mixing ratios, particularly of HNC, HC{sub 3}N, and HCN. We find good agreement with the recently detected mixing ratios of C{sub 2}H{sub 5}CN, with condensation playing an important role in determining the abundance of this molecule below 500 km. Of particular interest is the chemistry of acrylonitrile (C{sub 2}H{sub 3}CN) which has been suggested by Stevenson et al. as a molecule that could form biological membranes in an oxygen-deficient environment. With the inclusion of haze formation, we find good agreement of our model predictions of acrylonitrile with the available observations.

Land-atmosphere interaction patterns in southeastern South America using satellite products and climate models

Science.gov (United States)

Spennemann, P. C.; Salvia, M.; Ruscica, R. C.; Sörensson, A. A.; Grings, F.; Karszenbaum, H.

2018-02-01

In regions of strong Land-Atmosphere (L-A) interaction, soil moisture (SM) conditions can impact the atmosphere through modulating the land surface fluxes. The importance of the identification of L-A interaction regions lies in the potential improvement of the weather/seasonal forecast and the better understanding of the physical mechanisms involved. This study aims to compare the terrestrial segment of the L-A interaction from satellite products and climate models, motivated by previous modeling studies pointing out southeastern South America (SESA) as a L-A hotspot during austral summer. In addition, the L-A interaction under dry or wet anomalous conditions over SESA is analyzed. To identify L-A hotspots the AMSRE-LPRM SM and MODIS land surface temperature products; coupled climate models and uncoupled land surface models were used. SESA highlights as a strong L-A interaction hotspot when employing different metrics, temporal scales and independent datasets, showing consistency between models and satellite estimations. Both AMSRE-LPRM bands (X and C) are consistent showing a strong L-A interaction hotspot over the Pampas ecoregion. Intensification and a larger spatial extent of the L-A interaction for dry summers was observed in both satellite products and models compared to wet summers. These results, which were derived from measured physical variables, are encouraging and promising for future studies analyzing L-A interactions. L-A interaction analysis is proposed here as a meeting point between remote sensing and climate modelling communities of Argentina, within a region with the highest agricultural and livestock production of the continent, but with an important lack of in-situ SM observations.

Applications of the Regional Atmospheric Modeling System (RAMS) to provide input to photochemical grid models for the Lake Michigan Ozone Study (LMOS)

Energy Technology Data Exchange (ETDEWEB)

Lyons, W.A.; Tremback, C.J.; Pielke, R.A. [ASTeR, Inc., Ft. Collins, CO (United States); Eastman, J.L. [Colorado State Univ., Ft. Collins, CO (United States)

1994-12-31

In spite of stringent emission controls, numerous exceedances of the US ozone air quality standard have continued in the Lake Michigan region, especially during the very hot summers of 1987 and 1988. Analyses revealed that exceedances of the 120 PPB hourly standard were 400% more likely at monitors located within 20 km of the lakeshore. While the role of Lake Michigan in exacerbating regional air quality problems has been investigated for almost 20 years, the relative impacts of various phenomena upon regional photochemical air quality have yet to be quantified. In order to design a defensible regional emission control policy, LMOS sponsored the development of a comprehensive regional photochemical modeling system. This is comprised of an emission model, an advanced regional photochemical model, and a prognostic meteorological model.

A comparison of the WIND System atmospheric models and RASCAL

International Nuclear Information System (INIS)

Fast, J.D.

1991-01-01

A detailed comparison of the characteristics of the WIND System atmospheric models and the NRC's RASCAL code was made. The modeling systems differ substantially in the way input is entered and the way output is displayed. Nevertheless, using the same source term and meteorological input parameters, the WIND System atmospheric models and RASCAL produce similar results in most situations. The WIND System atmospheric model predictions and those made by RASCAL are within a factor of two at least 70% of the time and are within a factor of four 89% of the time. Significant differences in the dose between the models may occur during conditions of low wind speeds, strong atmospheric stability, and/or wet deposition as well as for many atmospheric cases involving cloud shine. Even though the numerical results are similar in most cases, there are many site-specific and operational characteristics that have been incorporated into the WIND System atmospheric models to provide SRS emergency response personnel with a more effective emergency response tool than is currently available from using RASCAL

Towards grid-converged wall-modeled LES of atmospheric boundary layer flows

Science.gov (United States)

Yellapantula, Shashank; Vijayakumar, Ganesh; Henry de Frahan, Marc; Churchfield, Matthew; Sprague, Michael

2017-11-01

Accurate characterization of incoming atmospheric boundary layer (ABL) turbulence is a critical factor in improving accuracy and predictive nature of simulation of wind farm flows. Modern commercial wind turbines operate in the log layer of the ABL that are typically simulated using wall-modeled large-eddy simulation (WMLES). One of the long-standing issues associated with wall modeling for LES and hybrid RANS-LES for atmospheric boundary layers is the over-prediction of the mean-velocity gradient, commonly referred to as log-layer mismatch. Kawai and Larsson in 2012, identified under-resolution of the near-wall region and the incorrect information received by the wall model as potential causes for the log-layer mismatch in WMLES of smooth-wall boundary-layer flows. To solve the log layer mismatch issue, they proposed linking the wall model to the LES solution at a physical of height of ym, instead of the first grid point. In this study, we extend their wall modeling approach to LES of the rough-wall ABL to investigate issues of log-layer mismatch and grid convergence. This work was funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Wind Energy Technologies Office, under Contract No. DE-AC36-08-GO28308 with the National Renewable Energy Laboratory.

Fire Influences on Atmospheric Composition, Air Quality, and Climate

Science.gov (United States)

Voulgarakis, Apostolos; Field, Robert D.

2015-01-01

Fires impact atmospheric composition through their emissions, which range from long-lived gases to short-lived gases and aerosols. Effects are typically larger in the tropics and boreal regions but can also be substantial in highly populated areas in the northern mid-latitudes. In all regions, fire can impact air quality and health. Similarly, its effect on large-scale atmospheric processes, including regional and global atmospheric chemistry and climate forcing, can be substantial, but this remains largely unexplored. The impacts are primarily realised in the boundary layer and lower free troposphere but can also be noticeable in upper troposphere/lower stratosphere (UT/LS) region, for the most intense fires. In this review, we summarise the recent literature on findings related to fire impact on atmospheric composition, air quality and climate. We explore both observational and modelling approaches and present information on key regions and on the globe as a whole. We also discuss the current and future directions in this area of research, focusing on the major advances in emission estimates, the emerging efforts to include fire as a component in Earth system modelling and the use of modelling to assess health impacts of fire emissions.

Experiments of reconstructing discrete atmospheric dynamic models from data (I)

Science.gov (United States)

Lin, Zhenshan; Zhu, Yanyu; Deng, Ziwang

1995-03-01

In this paper, we give some experimental results of our study in reconstructing discrete atmospheric dynamic models from data. After a great deal of numerical experiments, we found that the logistic map, x n + 1 = 1- μx {2/n}, could be used in monthly mean temperature prediction when it was approaching the chaotic region, and its predictive results were in reverse states to the practical data. This means that the nonlinear developing behavior of the monthly mean temperature system is bifurcating back into the critical chaotic states from the chaotic ones.

Regional climate model sensitivity to domain size

Energy Technology Data Exchange (ETDEWEB)

Leduc, Martin [Universite du Quebec a Montreal, Canadian Regional Climate Modelling and Diagnostics (CRCMD) Network, ESCER Centre, Montreal (Canada); UQAM/Ouranos, Montreal, QC (Canada); Laprise, Rene [Universite du Quebec a Montreal, Canadian Regional Climate Modelling and Diagnostics (CRCMD) Network, ESCER Centre, Montreal (Canada)

2009-05-15

Regional climate models are increasingly used to add small-scale features that are not present in their lateral boundary conditions (LBC). It is well known that the limited area over which a model is integrated must be large enough to allow the full development of small-scale features. On the other hand, integrations on very large domains have shown important departures from the driving data, unless large scale nudging is applied. The issue of domain size is studied here by using the ''perfect model'' approach. This method consists first of generating a high-resolution climatic simulation, nicknamed big brother (BB), over a large domain of integration. The next step is to degrade this dataset with a low-pass filter emulating the usual coarse-resolution LBC. The filtered nesting data (FBB) are hence used to drive a set of four simulations (LBs for Little Brothers), with the same model, but on progressively smaller domain sizes. The LB statistics for a climate sample of four winter months are compared with BB over a common region. The time average (stationary) and transient-eddy standard deviation patterns of the LB atmospheric fields generally improve in terms of spatial correlation with the reference (BB) when domain gets smaller. The extraction of the small-scale features by using a spectral filter allows detecting important underestimations of the transient-eddy variability in the vicinity of the inflow boundary, which can penalize the use of small domains (less than 100 x 100 grid points). The permanent ''spatial spin-up'' corresponds to the characteristic distance that the large-scale flow needs to travel before developing small-scale features. The spin-up distance tends to grow in size at higher levels in the atmosphere. (orig.)

Results of an interactively coupled atmospheric chemistry – general circulation model: Comparison with observations

Directory of Open Access Journals (Sweden)

R. Hein

Full Text Available The coupled climate-chemistry model ECHAM4.L39(DLR/CHEM is presented which enables a simultaneous treatment of meteorology and atmospheric chemistry and their feedbacks. This is the first model which interactively combines a general circulation model with a chemical model, employing most of the important reactions and species necessary to describe the stratospheric and upper tropospheric ozone chemistry, and which is computationally fast enough to allow long-term integrations with currently available computer resources. This is possible as the model time-step used for the chemistry can be chosen as large as the integration time-step for the dynamics. Vertically the atmosphere is discretized by 39 levels from the surface up to the top layer which is centred at 10 hPa, with a relatively high vertical resolution of approximately 700 m near the extra-tropical tropopause. We present the results of a control simulation representing recent conditions (1990 and compare it to available observations. The focus is on investigations of stratospheric dynamics and chemistry relevant to describe the stratospheric ozone layer. ECHAM4.L39(DLR/CHEM reproduces main features of stratospheric dynamics in the arctic vortex region, including stratospheric warming events. This constitutes a major improvement compared to earlier model versions. However, apparent shortcomings in Antarctic circulation and temperatures persist. The seasonal and interannual variability of the ozone layer is simulated in accordance with observations. Activation and deactivation of chlorine in the polar stratospheric vortices and their inter-hemispheric differences are reproduced. Considering methane oxidation as part of the dynamic-chemistry feedback results in an improved representation of the spatial distribution of stratospheric water vapour concentrations. The current model constitutes a powerful tool to investigate, for instance, the combined direct and indirect effects of anthropogenic

Technical discussions on Emissions and Atmospheric Modeling (TEAM)

Science.gov (United States)

Frost, G. J.; Henderson, B.; Lefer, B. L.

2017-12-01

A new informal activity, Technical discussions on Emissions and Atmospheric Modeling (TEAM), aims to improve the scientific understanding of emissions and atmospheric processes by leveraging resources through coordination, communication and collaboration between scientists in the Nation's environmental agencies. TEAM seeks to close information gaps that may be limiting emission inventory development and atmospheric modeling and to help identify related research areas that could benefit from additional coordinated efforts. TEAM is designed around webinars and in-person meetings on particular topics that are intended to facilitate active and sustained informal communications between technical staff at different agencies. The first series of TEAM webinars focuses on emissions of nitrogen oxides, a criteria pollutant impacting human and ecosystem health and a key precursor of ozone and particulate matter. Technical staff at Federal agencies with specific interests in emissions and atmospheric modeling are welcome to participate in TEAM.

Extracted atmospheric impairments on earth-sky signal quality in tropical regions at Ku-band

Science.gov (United States)

Al-Saegh, Ali Mohammed; Sali, Aduwati; Mandeep, J. S.; Ismail, Alyani

2013-11-01

Atmospheric condition variations were shown to have a major effect on the earth sky signal quality at Ku band. Moreover, such variations increased in the tropical regions as compared to temperate areas due to their different weather parameters. With the increase of recent satellite communication technology applications throughout the tropical countries and lack of information regarding the atmospheric impairments analysis, simulation and mitigation techniques, there is an ever increasing need for extracting a unique and accurate performance of the signal quality effects during highly natural tropical weather impairments. This paper presents a new method developed for proper analysis with distinctive and highly realistic performance evaluation for signal quality during the atmospheric conditions variations in 14 tropical areas from the four continents analyzed based on actual measured parameters. The method implementation includes signal attenuation, carrier to noise ratio, symbol energy to noise ratio, and symbol error rate at different areas and different modulation schemes. Furthermore, for improvement in analysis in terms of covering more remarkable regions in tropics, the paper provides new measurements data with analysis for certain region in tropics used as a test bed and to add measurement data of such area to the world's data base for future researchers. The results show a significant investigation and performance observation in terms of weather impairments in tropical regions in general and each region in that area in particular regarding the signal attenuation and error rates accompanied for several transmission schemes.

Electrical model of cold atmospheric plasma gun

Science.gov (United States)

Slutsker, Ya. Z.; Semenov, V. E.; Krasik, Ya. E.; Ryzhkov, M. A.; Felsteiner, J.; Binenbaum, Y.; Gil, Z.; Shtrichman, R.; Cohen, J. T.

2017-10-01

We present an analytical model of cold atmospheric plasma formed by a dielectric barrier discharge (DBD), which is based on the lumped and distributed elements of an equivalent electric circuit of this plasma. This model is applicable for a wide range of frequencies and amplitudes of the applied voltage pulses, no matter whether or not the generated plasma plume interacts with a target. The model allows quantitative estimation of the plasma plume length and the energy delivered to the plasma. Also, the results of this model can be used for the design of DBD guns which efficiently generate cold atmospheric plasma. A comparison of the results of the model with those obtained in experiments shows a fairly good agreement.

ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Heng, Kevin [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Workman, Jared, E-mail: kevin.heng@csh.unibe.ch, E-mail: jworkman@coloradomesa.edu [Colorado Mesa University, 1260 Kennedy Avenue, Grand Junction, CO 81501 (United States)

2014-08-01

Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

Cryosphere-hydrosphere interactions: numerical modeling using the Regional Ocean Modeling System (ROMS) at different scales

Science.gov (United States)

Bergamasco, A.; Budgell, W. P.; Carniel, S.; Sclavo, M.

2005-03-01

Conveyor belt circulation controls global climate through heat and water fluxes with atmosphere and from tropical to polar regions and vice versa. This circulation, commonly referred to as thermohaline circulation (THC), seems to have millennium time scale and nowadays--a non-glacial period--appears to be as rather stable. However, concern is raised by the buildup of CO2 and other greenhouse gases in the atmosphere (IPCC, Third assessment report: Climate Change 2001. A contribution of working group I, II and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge Univ. Press, UK) 2001, http://www.ipcc.ch) as these may affect the THC conveyor paths. Since it is widely recognized that dense-water formation sites act as primary sources in strengthening quasi-stable THC paths (Stommel H., Tellus131961224), in order to simulate properly the consequences of such scenarios a better understanding of these oceanic processes is needed. To successfully model these processes, air-sea-ice-integrated modelling approaches are often required. Here we focus on two polar regions using the Regional Ocean Modeling System (ROMS). In the first region investigated, the North Atlantic-Arctic, where open-ocean deep convection and open-sea ice formation and dispersion under the intense air-sea interactions are the major engines, we use a new version of the coupled hydrodynamic-ice ROMS model. The second area belongs to the Antarctica region inside the Southern Ocean, where brine rejections during ice formation inside shelf seas origin dense water that, flowing along the continental slope, overflow becoming eventually abyssal waters. Results show how nowadays integrated-modelling tasks have become more and more feasible and effective; numerical simulations dealing with large computational domains or challenging different climate scenarios can be run on multi-processors platforms and on systems like LINUX clusters, made of the same hardware as PCs, and

Cryosphere-hydrosphere interactions: Numerical modeling using the Regional Ocean Modeling System (ROMS) at different scales

International Nuclear Information System (INIS)

Bergamasco, A.; Carniel, S.; Sclavo, M.; Budgell, W.P.

2005-01-01

Conveyor belt circulation controls global climate through heat and water fluxes with atmosphere and from tropical to polar regions and vice versa. This circulation, commonly referred to as thermohaline circulation (THC), seems to have millennium time scale and nowadays-a non-glacial period-appears to be as rather stable. However, concern is raised by the buildup of CO 2 and other greenhouse gases in the atmosphere (IPCC, Third assessment report: Climate Change 2001. A contribution 01 working group I, n and In to the Third Assessment Report of the intergovernmental Panel on Climate Change (Cambridge Univ. Press, UK) 2001, http://www.ipcc.ch) as these may affect the THC conveyor paths. Since it is widely recognized that dense water formation sites ad as primary sources in strengthening quasi-stable THC paths (Stommel H., Tellus, 13 (1961) 224), in order to simulate properly the consequences of such scenarios a better understanding of these oceanic processes is needed. To successfully model these processes, air sea-ice-integrated modelling approaches are often required. Here we focus on two polar regions using the Regional Ocean Modeling System (ROMS). In the first region investigated, the North Atlantic-Arctic, where open-ocean Jeep convection and open-sea ire formation and dispersion under the intense air-sea interactions are the major engines, we use a new version of the coupled hydrodynamic-ice ROMS model. The second area belongs to the Antarctica region inside the Southern Ocean, where brine rejections during ice formation inside shelf seas origin dense water that, flowing along the continental slope, overflow becoming eventually abyssal waters. Results show how nowadays integrated-modelling tasks have become more and more feasible and effective; numerical simulations dealing with large computational domains or challenging different climate scenarios can be run on multi-processors platforms and on systems like LINUX clusters, made of the same hardware as PCs, and

A fusion of top-down and bottom-up modeling techniques to constrain regional scale carbon budgets

Science.gov (United States)

Goeckede, M.; Turner, D. P.; Michalak, A. M.; Vickers, D.; Law, B. E.

2009-12-01

The effort to constrain regional scale carbon budgets benefits from assimilating as many high quality data sources as possible in order to reduce uncertainties. Two of the most common approaches used in this field, bottom-up and top-down techniques, both have their strengths and weaknesses, and partly build on very different sources of information to train, drive, and validate the models. Within the context of the ORCA2 project, we follow both bottom-up and top-down modeling strategies with the ultimate objective of reconciling their surface flux estimates. The ORCA2 top-down component builds on a coupled WRF-STILT transport module that resolves the footprint function of a CO2 concentration measurement in high temporal and spatial resolution. Datasets involved in the current setup comprise GDAS meteorology, remote sensing products, VULCAN fossil fuel inventories, boundary conditions from CarbonTracker, and high-accuracy time series of atmospheric CO2 concentrations. Surface fluxes of CO2 are normally provided through a simple diagnostic model which is optimized against atmospheric observations. For the present study, we replaced the simple model with fluxes generated by an advanced bottom-up process model, Biome-BGC, which uses state-of-the-art algorithms to resolve plant-physiological processes, and 'grow' a biosphere based on biogeochemical conditions and climate history. This approach provides a more realistic description of biomass and nutrient pools than is the case for the simple model. The process model ingests various remote sensing data sources as well as high-resolution reanalysis meteorology, and can be trained against biometric inventories and eddy-covariance data. Linking the bottom-up flux fields to the atmospheric CO2 concentrations through the transport module allows evaluating the spatial representativeness of the BGC flux fields, and in that way assimilates more of the available information than either of the individual modeling techniques alone

Model coupler for coupling of atmospheric, oceanic, and terrestrial models

International Nuclear Information System (INIS)

Nagai, Haruyasu; Kobayashi, Takuya; Tsuduki, Katsunori; Kim, Keyong-Ok

2007-02-01

A numerical simulation system SPEEDI-MP, which is applicable for various environmental studies, consists of dynamical models and material transport models for the atmospheric, terrestrial, and oceanic environments, meteorological and geographical databases for model inputs, and system utilities for file management, visualization, analysis, etc., using graphical user interfaces (GUIs). As a numerical simulation tool, a model coupling program (model coupler) has been developed. It controls parallel calculations of several models and data exchanges among them to realize the dynamical coupling of the models. It is applicable for any models with three-dimensional structured grid system, which is used by most environmental and hydrodynamic models. A coupled model system for water circulation has been constructed with atmosphere, ocean, wave, hydrology, and land-surface models using the model coupler. Performance tests of the coupled model system for water circulation were also carried out for the flood event at Saudi Arabia in January 2005 and the storm surge case by the hurricane KATRINA in August 2005. (author)

Aerosol impacts on regional trends in atmospheric stagnation

Science.gov (United States)

Mascioli, N. R.; Fiore, A. M.; Previdi, M. J.

2017-12-01

Extreme pollution events pose a significant threat to human health and are a leading cause of premature mortality worldwide. While emissions of atmospheric pollutants and their precursors are projected to decrease in the future due to air quality legislation, future climate change may affect the underlying meteorological conditions that contribute to extreme pollution events. Stagnation events, characterized by weak winds and an absence of precipitation, contribute to extreme pollution by halting the removal of pollutants via advection and wet deposition. Here, we use a global climate model (GFDL-CM3) to show that regional stagnation trends over the historical period (1860-2005) are driven by changes in anthropogenic aerosol emissions, rather than rising greenhouse gases. In the northeastern and central United States, aerosol-induced changes in surface and upper level winds have produced significant decreases in the number of stagnant summer days, while decreasing precipitation in the southeast US has increased the number of stagnant summer days. Significant drying over eastern China in response to aerosol forcing contributed to increased stagnation. Additionally, this region was found to be particularly sensitive to changes in local emissions, indicating that improving air quality will also lessen stagnation. In Europe, we find a dipole pattern wherein stagnation decreases over southern Europe and increases over northern Europe in response to global increases in aerosol emissions. We hypothesize that this is due to changes in the large-scale circulation patterns associated with a poleward shift of the North Atlantic storm track. We find that in the future, the combination of declining aerosol emissions and the continued rise of greenhouse gas emissions will lead to a reversal of the historical stagnation trends.

Ocean-atmosphere dynamics during Hurricane Ida and Nor'Ida: An application of the coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system

Science.gov (United States)

Olabarrieta, Maitane; Warner, John C.; Armstrong, Brandy N.; Zambon, Joseph B.; He, Ruoying

2012-01-01

The coupled ocean–atmosphere–wave–sediment transport (COAWST) modeling system was used to investigate atmosphere–ocean–wave interactions in November 2009 during Hurricane Ida and its subsequent evolution to Nor’Ida, which was one of the most costly storm systems of the past two decades. One interesting aspect of this event is that it included two unique atmospheric extreme conditions, a hurricane and a nor’easter storm, which developed in regions with different oceanographic characteristics. Our modeled results were compared with several data sources, including GOES satellite infrared data, JASON-1 and JASON-2 altimeter data, CODAR measurements, and wave and tidal information from the National Data Buoy Center (NDBC) and the National Tidal Database. By performing a series of numerical runs, we were able to isolate the effect of the interaction terms between the atmosphere (modeled with Weather Research and Forecasting, the WRF model), the ocean (modeled with Regional Ocean Modeling System (ROMS)), and the wave propagation and generation model (modeled with Simulating Waves Nearshore (SWAN)). Special attention was given to the role of the ocean surface roughness. Three different ocean roughness closure models were analyzed: DGHQ (which is based on wave age), TY2001 (which is based on wave steepness), and OOST (which considers both the effects of wave age and steepness). Including the ocean roughness in the atmospheric module improved the wind intensity estimation and therefore also the wind waves, surface currents, and storm surge amplitude. For example, during the passage of Hurricane Ida through the Gulf of Mexico, the wind speeds were reduced due to wave-induced ocean roughness, resulting in better agreement with the measured winds. During Nor’Ida, including the wave-induced surface roughness changed the form and dimension of the main low pressure cell, affecting the intensity and direction of the winds. The combined wave age- and wave steepness

The Whole Atmosphere Community Climate Model

Science.gov (United States)

Boville, B. A.; Garcia, R. R.; Sassi, F.; Kinnison, D.; Roble, R. G.

The Whole Atmosphere Community Climate Model (WACCM) is an upward exten- sion of the National Center for Atmospheric Research Community Climate System Model. WACCM simulates the atmosphere from the surface to the lower thermosphere (140 km) and includes both dynamical and chemical components. The salient points of the model formulation will be summarized and several aspects of its performance will be discussed. Comparison with observations indicates that WACCM produces re- alistic temperature and zonal wind distributions. Both the mean state and interannual variability will be summarized. Temperature inversions in the midlatitude mesosphere have been reported by several authors and are also found in WACCM. These inver- sions are formed primarily by planetary wave forcing, but the background state on which they form also requires gravity wave forcing. The response to sea surface temperature (SST) anomalies will be examined by com- paring simulations with observed SSTs for 1950-1998 to a simulation with clima- tological annual cycle of SSTs. The response to ENSO events is found to extend though the winter stratosphere and mesosphere and a signal is also found at the sum- mer mesopause. The experimental framework allows the ENSO signal to be isolated, because no other forcings are included (e.g. solar variability and volcanic eruptions) which complicate the observational record. The temperature and wind variations asso- ciated with ENSO are large enough to generate significant perturbations in the chem- ical composition of the middle atmosphere, which will also be discussed.

A model of the primordial lunar atmosphere

Science.gov (United States)

Saxena, Prabal; Elkins-Tanton, Lindy; Petro, Noah; Mandell, Avi

2017-09-01

We create the first quantitative model for the early lunar atmosphere, coupled with a magma ocean crystallization model. Immediately after formation, the moon's surface was subject to a radiative environment that included contributions from the early Sun, a post-impact Earth that radiated like a mid-type M dwarf star, and a cooling global magma ocean. This radiative environment resulted in a largely Earth-side atmosphere on the Moon, ranging from ∼104 to ∼102 pascals, composed of heavy volatiles (Na and SiO). This atmosphere persisted through lid formation and was additionally characterized by supersonic winds that transported significant quantities of moderate volatiles and likely generated magma ocean waves. The existence of this atmosphere may have influenced the distribution of some moderate volatiles and created temperature asymmetries which influenced ocean flow and cooling. Such asymmetries may characterize young, tidally locked rocky bodies with global magma oceans and subject to intense irradiation.

Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model

International Nuclear Information System (INIS)

Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B.; Hao, Jiming

2014-01-01

China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35–50% of THg concentration and 50–70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. - Highlights: • China's anthropogenic mercury emission was 643.1 t in 2007. • GEOS-Chem model well reproduces the background Hg concentrations. • Anthropogenic emissions contribute 35–50% of Hg concentrations in polluted regions. • The priorities for mercury control in polluted regions are identified. - Anthropogenic Hg emissions are updated and their impacts on atmospheric mercury concentrations and depositions are quantified for China

Inception of the Laurentide Ice Sheet using asynchronous coupling of a regional atmospheric model and an ice model

Science.gov (United States)

Birch, L.; Cronin, T.; Tziperman, E.

2017-12-01

The climate over the past 0.8 million years has been dominated by ice ages. Ice sheets have grown about every 100 kyrs, starting from warm interglacials, until they spanned continents. State-of-the-art global climate models (GCMs) have difficulty simulating glacial inception, or the transition of Earth's climate from an interglacial to a glacial state. It has been suggested that this failure may be related to their poorly resolved local mountain topography, due to their coarse spatial resolution. We examine this idea as well as the possible role of ice flow dynamics missing in GCMs. We investigate the growth of the Laurentide Ice Sheet at 115 kya by focusing on the mountain glaciers of Canada's Baffin Island, where geologic evidence indicates the last inception occurred. We use the Weather Research and Forecasting model (WRF) in a regional, cloud-resolving configuration with resolved mountain terrain to explore how quickly Baffin Island could become glaciated with the favorable yet realizable conditions of 115 kya insolation, cool summers, and wet winters. Using the model-derived mountain glacier mass balance, we force an ice sheet model based on the shallow-ice approximation, capturing the ice flow that may be critical to the spread of ice sheets away from mountain ice caps. The ice sheet model calculates the surface area newly covered by ice and the change in the ice surface elevation, which we then use to run WRF again. Through this type of iterated asynchronous coupling, we investigate how the regional climate responds to both larger areas of ice cover and changes in ice surface elevation. In addition, we use the NOAH-MP Land model to characterize the importance of land processes, like refreezing. We find that initial ice growth on the Penny Ice Cap causes regional cooling that increases the accumulation on the Barnes Ice Cap. We investigate how ice and topography changes on Baffin Island may impact both the regional climate and the large-scale circulation.

Air Quality Modeling for the Urban Jackson, Mississippi Region Using a High Resolution WRF/Chem Model

Directory of Open Access Journals (Sweden)

Shelton J. Swanier

2011-06-01

Full Text Available In this study, an attempt was made to simulate the air quality with reference to ozone over the Jackson (Mississippi region using an online WRF/Chem (Weather Research and Forecasting–Chemistry model. The WRF/Chem model has the advantages of the integration of the meteorological and chemistry modules with the same computational grid and same physical parameterizations and includes the feedback between the atmospheric chemistry and physical processes. The model was designed to have three nested domains with the inner-most domain covering the study region with a resolution of 1 km. The model was integrated for 48 hours continuously starting from 0000 UTC of 6 June 2006 and the evolution of surface ozone and other precursor pollutants were analyzed. The model simulated atmospheric flow fields and distributions of NO2 and O3 were evaluated for each of the three different time periods. The GIS based spatial distribution maps for ozone, its precursors NO, NO2, CO and HONO and the back trajectories indicate that all the mobile sources in Jackson, Ridgeland and Madison contributing significantly for their formation. The present study demonstrates the applicability of WRF/Chem model to generate quantitative information at high spatial and temporal resolution for the development of decision support systems for air quality regulatory agencies and health administrators.

Understanding the Effect of Land Cover Classification on Model Estimates of Regional Carbon Cycling in the Boreal Forest Biome

Science.gov (United States)

Kimball, John; Kang, Sinkyu

2003-01-01

The original objectives of this proposed 3-year project were to: 1) quantify the respective contributions of land cover and disturbance (i.e., wild fire) to uncertainty associated with regional carbon source/sink estimates produced by a variety of boreal ecosystem models; 2) identify the model processes responsible for differences in simulated carbon source/sink patterns for the boreal forest; 3) validate model outputs using tower and field- based estimates of NEP and NPP; and 4) recommend/prioritize improvements to boreal ecosystem carbon models, which will better constrain regional source/sink estimates for atmospheric C02. These original objectives were subsequently distilled to fit within the constraints of a 1 -year study. This revised study involved a regional model intercomparison over the BOREAS study region involving Biome-BGC, and TEM (A.D. McGuire, UAF) ecosystem models. The major focus of these revised activities involved quantifying the sensitivity of regional model predictions associated with land cover classification uncertainties. We also evaluated the individual and combined effects of historical fire activity, historical atmospheric CO2 concentrations, and climate change on carbon and water flux simulations within the BOREAS study region.

Development of regional meteorological and atmospheric diffusion simulation system

International Nuclear Information System (INIS)

Kubota, Ryuji; Iwashige, Kengo; Kasano, Toshio

2002-01-01

Regional atmospheric diffusion online network (RADON) with atmospheric diffusion analysis code (ADAC) : a simulation program of diffusion of radioactive materials, volcanic ash, pollen, NOx and SOx was developed. This system can be executed in personal computer (PC) and note PC on Windows. Emission data consists of online, offline and default data. It uses the meteorology data sources such as meteorological forecasting mesh data, automated meteorological data acquisition system (AMeDAS) data, meteorological observation data in site and municipality observation data. The meteorological forecasting mesh data shows forecasting value of temperature, wind speed, wind direction and humidity in about two days. The nuclear environmental monitoring center retains the online data (meteorological data, emission source data, monitoring station data) in its PC server and can run forecasting or repeating calculation using these data and store and print out the calculation results. About 30 emission materials can be calculated simultaneously. This system can simulate a series of weather from the past and real time to the future. (S.Y.)

Improving the Ni I atomic model for solar and stellar atmospheric models

International Nuclear Information System (INIS)

Vieytes, M. C.; Fontenla, J. M.

2013-01-01

Neutral nickel (Ni I) is abundant in the solar atmosphere and is one of the important elements that contribute to the emission and absorption of radiation in the spectral range between 1900 and 3900 Å. Previously, the Solar Radiation Physical Modeling (SRPM) models of the solar atmosphere only considered a few levels of this species. Here, we improve the Ni I atomic model by taking into account 61 levels and 490 spectral lines. We compute the populations of these levels in full NLTE using the SRPM code and compare the resulting emerging spectrum with observations. The present atomic model significantly improves the calculation of the solar spectral irradiance at near-UV wavelengths, which is important for Earth atmospheric studies, and particularly for ozone chemistry.

Improving the Ni I atomic model for solar and stellar atmospheric models

Energy Technology Data Exchange (ETDEWEB)

Vieytes, M. C. [Instituto de de Astronomía y Física del Espacio, CONICET and UNTREF, Buenos Aires (Argentina); Fontenla, J. M., E-mail: mariela@iafe.uba.ar, E-mail: johnf@digidyna.com [North West Research Associates, 3380 Mitchell Lane, Boulder, CO 80301 (United States)

2013-06-01

Neutral nickel (Ni I) is abundant in the solar atmosphere and is one of the important elements that contribute to the emission and absorption of radiation in the spectral range between 1900 and 3900 Å. Previously, the Solar Radiation Physical Modeling (SRPM) models of the solar atmosphere only considered a few levels of this species. Here, we improve the Ni I atomic model by taking into account 61 levels and 490 spectral lines. We compute the populations of these levels in full NLTE using the SRPM code and compare the resulting emerging spectrum with observations. The present atomic model significantly improves the calculation of the solar spectral irradiance at near-UV wavelengths, which is important for Earth atmospheric studies, and particularly for ozone chemistry.

Wildfire potential evaluation during a drought event with a regional climate model and NDVI

Science.gov (United States)

Y. Liu; J. Stanturf; S. Goodrick

2010-01-01

Regional climate modeling is a technique for simulating high-resolution physical processes in the atmosphere, soil and vegetation. It can be used to evaluate wildfire potential by either providing meteorological conditions for computation of fire indices or predicting soil moisture as a direct measure of fire potential. This study examines these roles using a regional...

Atmospheric greenhouse effect - simple model; Atmosfaerens drivhuseffekt - enkel modell

Energy Technology Data Exchange (ETDEWEB)

Kanestroem, Ingolf; Henriksen, Thormod

2011-07-01

The article shows a simple model for the atmospheric greenhouse effect based on consideration of both the sun and earth as 'black bodies', so that the physical laws that apply to them, may be used. Furthermore, explained why some gases are greenhouse gases, but other gases in the atmosphere has no greenhouse effect. But first, some important concepts and physical laws encountered in the article, are repeated. (AG)

MODELING ATMOSPHERIC EMISSION FOR CMB GROUND-BASED OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Errard, J.; Borrill, J. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Ade, P. A. R. [School of Physics and Astronomy, Cardiff University, Cardiff CF10 3XQ (United Kingdom); Akiba, Y.; Chinone, Y. [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Arnold, K.; Atlas, M.; Barron, D.; Elleflot, T. [Department of Physics, University of California, San Diego, CA 92093-0424 (United States); Baccigalupi, C.; Fabbian, G. [International School for Advanced Studies (SISSA), Trieste I-34014 (Italy); Boettger, D. [Department of Astronomy, Pontifica Universidad Catolica de Chile (Chile); Chapman, S. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, B3H 4R2 (Canada); Cukierman, A. [Department of Physics, University of California, Berkeley, CA 94720 (United States); Delabrouille, J. [AstroParticule et Cosmologie, Univ Paris Diderot, CNRS/IN2P3, CEA/Irfu, Obs de Paris, Sorbonne Paris Cité (France); Dobbs, M.; Gilbert, A. [Physics Department, McGill University, Montreal, QC H3A 0G4 (Canada); Ducout, A.; Feeney, S. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Feng, C. [Department of Physics and Astronomy, University of California, Irvine (United States); and others

2015-08-10

Atmosphere is one of the most important noise sources for ground-based cosmic microwave background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3D-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive a new analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using an original numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the polarbear-i project first season data set. We derive a new 1.0% upper limit on the linear polarization fraction of atmospheric emission. We also compare our results to previous studies and weather station measurements. The proposed model can be used for realistic simulations of future ground-based CMB observations.

Experimental and Numerical Modelling of CO2 Atmospheric Dispersion in Hazardous Gas Emission Sites.

Science.gov (United States)

Gasparini, A.; sainz Gracia, A. S.; Grandia, F.; Bruno, J.

2015-12-01

Under stable atmospheric conditions and/or in presence of topographic depressions, CO2 concentrations can reach high values resulting in lethal effect to living organisms. The distribution of denser than air gases released from the underground is governed by gravity, turbulence and dispersion. Once emitted, the gas distribution is initially driven by buoyancy and a gas cloud accumulates on the ground (gravitational phase); with time the density gradient becomes less important due to dispersion or mixing and gas distribution is mainly governed by wind and atmospheric turbulence (passive dispersion phase). Natural analogues provide evidences of the impact of CO2 leakage. Dangerous CO2 concentration in atmosphere related to underground emission have been occasionally reported although the conditions favouring the persistence of such a concentration are barely studied.In this work, the dynamics of CO2 in the atmosphere after ground emission is assessed to quantify their potential risk. Two approaches have been followed: (1) direct measurement of air concentration in a natural emission site, where formation of a "CO2 lake" is common and (2) numerical atmospheric modelling. Two sites with different morphology were studied: (a) the Cañada Real site, a flat terrain in the Volcanic Field of Campo de Calatrava (Spain); (b) the Solforata di Pomezia site, a rough terrain in the Alban Hills Volcanic Region (Italy). The comparison between field data and model calculations reveal that numerical dispersion models are capable of predicting the formation of CO2 accumulation over the ground as a consequence of underground gas emission. Therefore, atmospheric modelling could be included as a valuable methodology in the risk assessment of leakage in natural degassing systems and in CCS projects. Conclusions from this work provide clues on whether leakage may be a real risk for humans and under which conditions this risk needs to be included in the risk assessment.

TMAP: Tübingen NLTE Model-Atmosphere Package

Science.gov (United States)

Werner, Klaus; Dreizler, Stefan; Rauch, Thomas

2012-12-01

The Tübingen NLTE Model-Atmosphere Package (TMAP) is a tool to calculate stellar atmospheres in spherical or plane-parallel geometry in hydrostatic and radiative equilibrium allowing departures from local thermodynamic equilibrium (LTE) for the population of atomic levels. It is based on the Accelerated Lambda Iteration (ALI) method and is able to account for line blanketing by metals. All elements from hydrogen to nickel may be included in the calculation with model atoms which are tailored for the aims of the user.

Combining super-ensembles and statistical emulation to improve a regional climate and vegetation model

Science.gov (United States)

Hawkins, L. R.; Rupp, D. E.; Li, S.; Sarah, S.; McNeall, D. J.; Mote, P.; Betts, R. A.; Wallom, D.

2017-12-01

Changing regional patterns of surface temperature, precipitation, and humidity may cause ecosystem-scale changes in vegetation, altering the distribution of trees, shrubs, and grasses. A changing vegetation distribution, in turn, alters the albedo, latent heat flux, and carbon exchanged with the atmosphere with resulting feedbacks onto the regional climate. However, a wide range of earth-system processes that affect the carbon, energy, and hydrologic cycles occur at sub grid scales in climate models and must be parameterized. The appropriate parameter values in such parameterizations are often poorly constrained, leading to uncertainty in predictions of how the ecosystem will respond to changes in forcing. To better understand the sensitivity of regional climate to parameter selection and to improve regional climate and vegetation simulations, we used a large perturbed physics ensemble and a suite of statistical emulators. We dynamically downscaled a super-ensemble (multiple parameter sets and multiple initial conditions) of global climate simulations using a 25-km resolution regional climate model HadRM3p with the land-surface scheme MOSES2 and dynamic vegetation module TRIFFID. We simultaneously perturbed land surface parameters relating to the exchange of carbon, water, and energy between the land surface and atmosphere in a large super-ensemble of regional climate simulations over the western US. Statistical emulation was used as a computationally cost-effective tool to explore uncertainties in interactions. Regions of parameter space that did not satisfy observational constraints were eliminated and an ensemble of parameter sets that reduce regional biases and span a range of plausible interactions among earth system processes were selected. This study demonstrated that by combining super-ensemble simulations with statistical emulation, simulations of regional climate could be improved while simultaneously accounting for a range of plausible land-atmosphere

EMMA model: an advanced operational mesoscale air quality model for urban and regional environments

International Nuclear Information System (INIS)

Jose, R.S.; Rodriguez, M.A.; Cortes, E.; Gonzalez, R.M.

1999-01-01

Mesoscale air quality models are an important tool to forecast and analyse the air quality in regional and urban areas. In recent years an increased interest has been shown by decision makers in these types of software tools. The complexity of such a model has grown exponentially with the increase of computer power. Nowadays, medium workstations can run operational versions of these modelling systems successfully. Presents a complex mesoscale air quality model which has been installed in the Environmental Office of the Madrid community (Spain) in order to forecast accurately the ozone, nitrogen dioxide and sulphur dioxide air concentrations in a 3D domain centred on Madrid city. Describes the challenging scientific matters to be solved in order to develop an operational version of the atmospheric mesoscale numerical pollution model for urban and regional areas (ANA). Some encouraging results have been achieved in the attempts to improve the accuracy of the predictions made by the version already installed. (Author)

Impact of atmospheric components on solar clear-sky models at different elevation: Case study Canary Islands

International Nuclear Information System (INIS)

Antonanzas-Torres, F.; Antonanzas, J.; Urraca, R.; Alia-Martinez, M.; Martinez-de-Pison, F.J.

2016-01-01

Highlights: • Assessment on the performance of solar clear-sky models at different altitude. • SOLIS and REST2 clear-sky models were superior with fine atmospheric inputs. • ESRA proved more robust with low spatial resolution atmospheric inputs. • Over-estimation occurred at the lower site when using inputs from the upper site. - Abstract: The estimation of clear-sky solar irradiance via clear-sky models depends on reliable values of aerosol optical depth, water vapor and ozone content. These atmospheric variables are rarely on-site measured and are generally provided as gridded estimates in very low spatial resolution (1°). The high spatial variability of atmospheric variables within the grid resolution (pixel) leads to important errors in those areas with great atmospheric variability, such as in mountainous regions. In this paper, the performance of three clear-sky solar irradiance models was evaluated in a site with especially great elevation range, the Izana station from the Baseline Surface Radiation Network (Tenerife, Canary Islands) located at a high elevation (2373 m) and just 14 km from the ocean. Aerosols data were obtained from measurements from the Aerosol Robotic Network (AERONET) at the same site. The evaluation was also compared with global horizontal irradiance estimations with clear-sky models in the Guimar station, located at a lower elevation (156 m) and only 11.5 km away from Izana. Results showed a strong influence of elevation on solar radiation estimation under clear-sky conditions.

Development of scheme for predicting atmospheric dispersion of radionuclides during nuclear emergency by using atmospheric dynamic model

Energy Technology Data Exchange (ETDEWEB)

Nagai, Haruyasu; Chino, Masamichi; Yamazawa, Hiromi (Japan Atomic Energy Research Inst., Tokyo (Japan))

1999-07-01

The meteorological forecast models are critically important for the accuracy of predicting the atmospheric dispersion of radionuclides discharged into atmosphere during nuclear emergencies. Thus, this paper describes a new scheme for predicting environmental impacts due to accidental release of radionuclides by using an atmospheric dynamic model PHYSIC. The advantages of introducing PHYSIC are, (1) three-dimensional local meteorological forecasts can be conducted, (2) synoptic meteorological changes can be considered by inputting grid data of synoptic forecasts from Japan Meteorological Agency to PHYSIC as initial and boundary conditions, (3) forecasts can be improved by nudging method using local meteorological observations, and (4) atmospheric dispersion model can consider the variation of the mixed layer. (author)

Development of scheme for predicting atmospheric dispersion of radionuclides during nuclear emergency by using atmospheric dynamic model

International Nuclear Information System (INIS)

Nagai, Haruyasu; Chino, Masamichi; Yamazawa, Hiromi

1999-01-01

The meteorological forecast models are critically important for the accuracy of predicting the atmospheric dispersion of radionuclides discharged into atmosphere during nuclear emergencies. Thus, this paper describes a new scheme for predicting environmental impacts due to accidental release of radionuclides by using an atmospheric dynamic model PHYSIC. The advantages of introducing PHYSIC are, (1) three-dimensional local meteorological forecasts can be conducted, (2) synoptic meteorological changes can be considered by inputting grid data of synoptic forecasts from Japan Meteorological Agency to PHYSIC as initial and boundary conditions, (3) forecasts can be improved by nudging method using local meteorological observations, and (4) atmospheric dispersion model can consider the variation of the mixed layer. (author)

NLTE Model Atmospheres for Super-Soft X-ray Sources

Science.gov (United States)

Rauch, Thomas; Werner, Klaus

2009-09-01

Spectral analysis by means of fully line-blanketed Non-LTE model atmospheres has arrived at a high level of sophistication. The Tübingen NLTE Model Atmosphere Package (TMAP) is used to calculate plane-parallel NLTE model atmospheres which are in radiative and hydrostatic equilibrium. Although TMAP is not especially designed for the calculation of burst spectra of novae, spectral energy distributions (SEDs) calculated from TMAP models are well suited e.g. for abundance determinations of Super Soft X-ray Sources like nova V4743 Sgr or line identifications in observations of neutron stars with low magnetic fields in low-mass X-ray binaries (LMXBs) like EXO 0748-676.

A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms

Directory of Open Access Journals (Sweden)

G. Sarwar

2013-10-01

Full Text Available We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2 into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 enhances ozone compared to CB05TU at all ambient levels. Although it exhibited greater overestimates at lower observed concentrations, it displayed an improved performance at higher observed concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. Any air pollution control strategies developed using the two mechanisms do not differ appreciably.

Use of MODIS Satellite Images and an Atmospheric Dust Transport Model To Evaluate Juniperus spp. Pollen Phenology and Dispersal

Science.gov (United States)

Luvall, J. C.; Sprigg, W. A.; Levetin, Estelle; Huete, Alfredo; Nickovic, S.; Pejanovic, G. A.; Vukovic, A.; VandeWater, P. K.; Myers, O. B.; Budge, A. M.;

Recent global CO2 flux inferred from atmospheric CO2 observations and its regional analyses

Directory of Open Access Journals (Sweden)

J. M. Chen

2011-11-01

Full Text Available The net surface exchange of CO2 for the years 2002–2007 is inferred from 12 181 atmospheric CO2 concentration data with a time-dependent Bayesian synthesis inversion scheme. Monthly CO2 fluxes are optimized for 30 regions of the North America and 20 regions for the rest of the globe. Although there have been many previous multiyear inversion studies, the reliability of atmospheric inversion techniques has not yet been systematically evaluated for quantifying regional interannual variability in the carbon cycle. In this study, the global interannual variability of the CO2 flux is found to be dominated by terrestrial ecosystems, particularly by tropical land, and the variations of regional terrestrial carbon fluxes are closely related to climate variations. These interannual variations are mostly caused by abnormal meteorological conditions in a few months in the year or part of a growing season and cannot be well represented using annual means, suggesting that we should pay attention to finer temporal climate variations in ecosystem modeling. We find that, excluding fossil fuel and biomass burning emissions, terrestrial ecosystems and oceans absorb an average of 3.63 ± 0.49 and 1.94 ± 0.41 Pg C yr−1, respectively. The terrestrial uptake is mainly in northern land while the tropical and southern lands contribute 0.62 ± 0.47, and 0.67 ± 0.34 Pg C yr−1 to the sink, respectively. In North America, terrestrial ecosystems absorb 0.89 ± 0.18 Pg C yr−1 on average with a strong flux density found in the south-east of the continent.

Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

Directory of Open Access Journals (Sweden)

L. Liu

2017-08-01

Full Text Available China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen (Nr. Atmospheric ammonia (NH3 and nitrogen dioxide (NO2 are the most important precursors for Nr compounds (including N2O5, HNO3, HONO and particulate NO3− and NH4+ in the atmosphere. Understanding the changes in NH3 and NO2 has important implications for the regulation of anthropogenic Nr emissions and is a requirement for assessing the consequence of environmental impacts. We conducted the temporal trend analysis of atmospheric NH3 and NO2 on a national scale since 1980 based on emission data (during 1980–2010, satellite observation (for NH3 since 2008 and for NO2 since 2005 and atmospheric chemistry transport modeling (during 2008–2015.Based on the emission data, during 1980–2010, significant continuous increasing trends in both NH3 and NOx were observed in REAS (Regional Emission inventory in Asia, for NH3 0.17 and for NOx 0.16 kg N ha−1 yr−2 and EDGAR (Emissions Database for Global Atmospheric Research, for NH3 0.24 and for NOx 0.17 kg N ha−1 yr−2 over China. Based on the satellite data and atmospheric chemistry transport model (CTM MOZART-4 (Model for Ozone and Related chemical Tracers, version 4, the NO2 columns over China increased significantly from 2005 to 2011 and then decreased significantly from 2011 to 2015; the satellite-retrieved NH3 columns from 2008 to 2014 increased at a rate of 2.37 % yr−1. The decrease in NO2 columns since 2011 may result from more stringent strategies taken to control NOx emissions during the 12th Five Year Plan, while no control policy has focused on NH3 emissions. Our findings provided an overall insight into the temporal trends of both NO2 and NH3 since 1980 based on emission data, satellite observations and atmospheric transport modeling. These findings can provide a scientific background for policy makers that are attempting to control atmospheric

Soil Methanotrophy Model (MeMo v1.0: a process-based model to quantify global uptake of atmospheric methane by soil

Directory of Open Access Journals (Sweden)

F. Murguia-Flores

2018-06-01

Full Text Available Soil bacteria known as methanotrophs are the sole biological sink for atmospheric methane (CH4, a potent greenhouse gas that is responsible for  ∼  20 % of the human-driven increase in radiative forcing since pre-industrial times. Soil methanotrophy is controlled by a plethora of factors, including temperature, soil texture, moisture and nitrogen content, resulting in spatially and temporally heterogeneous rates of soil methanotrophy. As a consequence, the exact magnitude of the global soil sink, as well as its temporal and spatial variability, remains poorly constrained. We developed a process-based model (Methanotrophy Model; MeMo v1.0 to simulate and quantify the uptake of atmospheric CH4 by soils at the global scale. MeMo builds on previous models by Ridgwell et al. (1999 and Curry (2007 by introducing several advances, including (1 a general analytical solution of the one-dimensional diffusion–reaction equation in porous media, (2 a refined representation of nitrogen inhibition on soil methanotrophy, (3 updated factors governing the influence of soil moisture and temperature on CH4 oxidation rates and (4 the ability to evaluate the impact of autochthonous soil CH4 sources on uptake of atmospheric CH4. We show that the improved structural and parametric representation of key drivers of soil methanotrophy in MeMo results in a better fit to observational data. A global simulation of soil methanotrophy for the period 1990–2009 using MeMo yielded an average annual sink of 33.5 ± 0.6 Tg CH4 yr−1. Warm and semi-arid regions (tropical deciduous forest and open shrubland had the highest CH4 uptake rates of 602 and 518 mg CH4 m−2 yr−1, respectively. In these regions, favourable annual soil moisture content ( ∼  20 % saturation and low seasonal temperature variations (variations  <   ∼  6 °C provided optimal conditions for soil methanotrophy and soil–atmosphere gas exchange

Neutron activation analysis of the atmosphere content in the Central Asia south regions

International Nuclear Information System (INIS)

Niyazova, O.A.; Turaev, Eh.Yu.

2001-01-01

By the method of neutron activation analysis a atmospheric air elementary content of south regions of Uzbekistan and Turkmenistan during the 'Afghan' dust-storm were studied. Comparison with data for atmospheric air before nad after this phenomenon was carried out.It shown, that during the 'Afghan' dust-storm the elements concentration of Au, La, Na, Sm, Hg, Cs, Zn, Co is increased in to 3-4 times. Concentration of Sc and Fe is increasing into 8-9 times. In the atmosphere with the storm beginning the Ce and Cr elements are appealing, its are absent before the 'Afghan' dust-storm. The surprise result, that Br element in air during the dust storm is disappearing

Meteorological uncertainty of atmospheric dispersion model results (MUD)

International Nuclear Information System (INIS)

Havskov Soerensen, J.; Amstrup, B.; Feddersen, H.

2013-08-01

The MUD project addresses assessment of uncertainties of atmospheric dispersion model predictions, as well as possibilities for optimum presentation to decision makers. Previously, it has not been possible to estimate such uncertainties quantitatively, but merely to calculate the 'most likely' dispersion scenario. However, recent developments in numerical weather prediction (NWP) include probabilistic forecasting techniques, which can be utilised also for long-range atmospheric dispersion models. The ensemble statistical methods developed and applied to NWP models aim at describing the inherent uncertainties of the meteorological model results. These uncertainties stem from e.g. limits in meteorological observations used to initialise meteorological forecast series. By perturbing e.g. the initial state of an NWP model run in agreement with the available observational data, an ensemble of meteorological forecasts is produced from which uncertainties in the various meteorological parameters are estimated, e.g. probabilities for rain. Corresponding ensembles of atmospheric dispersion can now be computed from which uncertainties of predicted radionuclide concentration and deposition patterns can be derived. (Author)

Modeling the Impacts of Global Climate and Regional Land Use Change on Regional Climate, Air Quality and Public Health in the New York Metropolitan Region

Science.gov (United States)

Rosenthal, J. E.; Knowlton, K. M.; Kinney, P. L.

2002-12-01

exposures and responses to heat stress and air quality differ as a function of socio-economic status and race/ethnicity across the region? The model systems used for this study are the Goddard Institute for Space Studies (GISS) Global Atmosphere-Ocean Model; the Regional Atmospheric Modeling System (RAMS) and PennState/NCAR MM5 mesoscale meteorological models; the SLEUTH land use model; the Sparse Matrix Operator Kernel Emissions Modeling System (SMOKE); the Community Multiscale Air Quality (CMAQ) and Comprehensive Air Quality Model with Extensions (CAMx) models for simulating regional air quality; and exposure-risk coefficients for assessing population health impacts based on exposure to extreme heat, fine particulates (PM2.5) and ozone. Two different IPCC global emission scenarios and two different regional land use growth scenarios are considered in the simulations, spanning a range of possible futures. In addition to base simulations for selected time periods in the decade 1990 - 2000, the integrated model is used to simulate future scenarios in the 2020s, 2050s, and 2080s. Predictions from both the meteorological models and the air quality models are compared against available observations for the simulations in the 1990s to establish baseline model performance. A series of sensitivity tests will address whether changes in meteorology due to global climate change, changes in regional land use, or changes in emissions have the largest impact on predicted ozone and particulate matter concentrations.

Two centuries of observed atmospheric variability and change over the North Sea region

Science.gov (United States)

Stendel, Martin; van den Besselaar, Else; Hannachi, Abdel; Kent, Elizabeth; Lefebvre, Christiana; Rosenhagen, Gudrun; Schenk, Frederik; van der Schrier, Gerard; Woollings, Tim

2016-04-01

In the upcoming North Sea Region Climate Change Assessment (NOSCCA), we present a synthesis of current knowledge about past, present and possible future climate change in the North Sea region. A climate change assessment from published scientific work has been conducted as a kind of regional IPCC report, and a book has been produced that will be published by Springer in 2016. In the framework of the NOSCCA project, we examine past and present studies of variability and changes in atmospheric variables within the North Sea region over the instrumental period, roughly the past 200 years, based on observations and reanalyses. The variables addressed in this presentation are large-scale circulation, pressure and wind, surface air temperature, precipitation and radiative properties (clouds, solar radiation, and sunshine duration). While air temperature over land, not unexpectedly, has increased everywhere in the North Sea region, with strongest trends in spring and in the north of the region, a precipitation increase has been observed in the north and a decrease in the south of the region. This pattern goes along with a north-eastward shift of storm tracks and is in agreement with climate model projections under enhanced greenhouse gas concentrations. For other variables, it is not obvious which part of the observed changes may be due to anthropogenic activities and which is internally forced. It remains also unclear to what extent atmospheric circulation over the North Sea region is influenced by distant factors, in particular Arctic sea-ice decline in recent decades. There are indications of an increase in the number of deep cyclones (but not in the total number of cyclones), while storminess since the late 19th century shows no robust trends. The persistence of circulation types appears to have increased over the last century, and consequently, there is an indication for 'more extreme' extreme events. However, changes in extreme weather events are difficult to assess

Model Stellar Atmospheres and Real Stellar Atmospheres and Status of the ATLAS12 Opacity Sampling Program and of New Programs for Rosseland and for Distribution Function Opacity

Science.gov (United States)

Kurucz, Robert L.

1996-01-01

I discuss errors in theory and in interpreting observations that are produced by the failure to consider resolution in space, time, and energy. I discuss convection in stellar model atmospheres and in stars. Large errors in abundances are possible such as the factor of ten error in the Li abundance for extreme Population II stars. Finally I discuss the variation of microturbulent velocity with depth, effective temperature, gravity, and abundance. These variations must be dealt with in computing models and grids and in any type of photometric calibration. I have also developed a new opacity-sampling version of my model atmosphere program called ATLAS12. It recognizes more than 1000 atomic and molecular species, each in up to 10 isotopic forms. It can treat all ions of the elements up through Zn and the first 5 ions of heavier elements up through Es. The elemental and isotopic abundances are treated as variables with depth. The fluxes predicted by ATLAS12 are not accurate in intermediate or narrow bandpass intervals because the sample size is too small. A special stripped version of the spectrum synthesis program SYNTHE is used to generate the surface flux for the converged model using the line data on CD-ROMs 1 and 15. ATLAS12 can be used to produce improved models for Am and Ap stars. It should be very useful for investigating diffusion effects in atmospheres. It can be used to model exciting stars for H II regions with abundances consistent with those of the H II region. These programs and line files will be distributed on CD-ROMs.

Atmospheric Composition Change: Climate-Chemistry Interactions

Science.gov (United States)

Isaksen, I.S.A.; Granier, C.; Myhre, G.; Bernsten, T. K.; Dalsoren, S. B.; Gauss, S.; Klimont, Z.; Benestad, R.; Bousquet, P.; Collins, W.;

A global hybrid coupled model based on atmosphere-SST feedbacks

Energy Technology Data Exchange (ETDEWEB)

Cimatoribus, Andrea A.; Drijfhout, Sybren S. [Royal Netherlands Meteorological Institute, De Bilt (Netherlands); Dijkstra, Henk A. [Utrecht University, Institute for Marine and Atmospheric Research Utrecht, Utrecht (Netherlands)

2012-02-15

A global hybrid coupled model is developed, with the aim of studying the effects of ocean-atmosphere feedbacks on the stability of the Atlantic meridional overturning circulation. The model includes a global ocean general circulation model and a statistical atmosphere model. The statistical atmosphere model is based on linear regressions of data from a fully coupled climate model on sea surface temperature both locally and hemispherically averaged, being the footprint of Atlantic meridional overturning variability. It provides dynamic boundary conditions to the ocean model for heat, freshwater and wind-stress. A basic but consistent representation of ocean-atmosphere feedbacks is captured in the hybrid coupled model and it is more than 10 times faster than the fully coupled climate model. The hybrid coupled model reaches a steady state with a climate close to the one of the fully coupled climate model, and the two models also have a similar response (collapse) of the Atlantic meridional overturning circulation to a freshwater hosing applied in the northern North Atlantic. (orig.)

An Empirical Study of Atmospheric Correction Procedures for Regional Infrasound Amplitudes with Ground Truth.

Science.gov (United States)

Howard, J. E.

2014-12-01

This study focusses on improving methods of accounting for atmospheric effects on infrasound amplitudes observed on arrays at regional distances in the southwestern United States. Recordings at ranges of 150 to nearly 300 km from a repeating ground truth source of small HE explosions are used. The explosions range in actual weight from approximately 2000-4000 lbs. and are detonated year-round which provides signals for a wide range of atmospheric conditions. Three methods of correcting the observed amplitudes for atmospheric effects are investigated with the data set. The first corrects amplitudes for upper stratospheric wind as developed by Mutschlecner and Whitaker (1999) and uses the average wind speed between 45-55 km altitudes in the direction of propagation to derive an empirical correction formula. This approach was developed using large chemical and nuclear explosions and is tested with the smaller explosions for which shorter wavelengths cause the energy to be scattered by the smaller scale structure of the atmosphere. The second approach isa semi-empirical method using ray tracing to determine wind speed at ray turning heights where the wind estimates replace the wind values in the existing formula. Finally, parabolic equation (PE) modeling is used to predict the amplitudes at the arrays at 1 Hz. The PE amplitudes are compared to the observed amplitudes with a narrow band filter centered at 1 Hz. An analysis is performed of the conditions under which the empirical and semi-empirical methods fail and full wave methods must be used.

Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

Science.gov (United States)

Katata, G.; Chino, M.; Kobayashi, T.; Terada, H.; Ota, M.; Nagai, H.; Kajino, M.; Draxler, R.; Hort, M. C.; Malo, A.; Torii, T.; Sanada, Y.

2014-06-01

release rates associated with reactor pressure changes in Units 2 and 3. The modified WSPEEDI-II simulation using the new source term reproduced local and regional patterns of cumulative surface deposition of total 131I and 137Cs and air dose rate obtained by airborne surveys. The new source term was also tested using three atmospheric dispersion models (MLDP0, HYSPLIT, and NAME) for regional and global calculations and showed good agreement between calculated and observed air concentration and surface deposition of 137Cs in East Japan. Moreover, HYSPLIT model using the new source term also reproduced the plume arrivals at several countries abroad showing a good correlation with measured air concentration data. A large part of deposition pattern of total 131I and 137Cs in East Japan was explained by in-cloud particulate scavenging. However, for the regional scale contaminated areas, there were large uncertainties due to the overestimation of rainfall amounts and the underestimation of fogwater and drizzle depositions. The computations showed that approximately 27% of 137Cs discharged from FNPS1 deposited to the land in East Japan, mostly in forest areas.

Portable University Model of the Atmosphere (PUMA)

Energy Technology Data Exchange (ETDEWEB)

Fraedrich, K.; Kirk, E.; Lunkeit, F. [Hamburg Univ. (Germany). Meteorologisches Inst.

1998-10-01

The Portable University Model of the Atmosphere (PUMA) is based on the Reading multi-level spectral model SGCM (Simple Global Circulation Model) described by Hoskins and Simmons (1975) and James and Gray (1986). Originally developed as a numerical prediction model, it was changed to perform as a circulation model. For example, James and Gray (1986) studied the influence of surface friction on the circulation of a baroclinic atmosphere, James and James (1992), and James et al. (1994) investigated ultra-low-frequency variability, and Mole and James (1990) analyzed the baroclinic adjustment in the context of a zonally varying flow. Frisius et al. (1998) simulated an idealized storm track by embedding a dipole structure in a zonally symmetric forcing field and Lunkeit et al. (1998) investigated the sensitivity of GCM (General Circulation Model) scenarios by an adaption technique applicapable to SGCMs. (orig.)

Atmospheric residence times of continental aerosols

International Nuclear Information System (INIS)

Balkanski, Y.J.

1991-01-01

The global atmospheric distributions of Rn-222 are simulated with a three-dimensional model of atmospheric transport based on the meteorology of the NASA Goddard Institute for Space Studies (GISS) general circulation model. The short-lived radioactive gas Rn-222 (half-life = 3.8d) is emitted almost exclusively from land, at a relatively uniform rate; hence it is an excellent tracer of continental influences. Lead-210 is produced by decay of Rn-222 and immediately condenses to preexisting aerosol surfaces. It provides an excellent measure of aerosol residence times in the atmosphere because its source is accurately defined by the Rn-222 distribution. Results from the three-dimensional model are compared to measurements of Rn-222 and Pb-210 atmospheric concentrations to evaluate model's long-range transport over oceanic regions and to study the deposition mechanisms of atmospheric aerosols. Model results for Rn-222 are used to examine the long-range transport of continental air over two selected oceanic regions, the subantarctic Indian Ocean and the North Pacific. It is shown that the fast transport of air from southern Africa causes substantial continental pollution at southern mid-latitudes, a region usually regarded as pristine. Air over the North Pacific is heavily impacted by continental influences year round, but the altitude at which the transport occurs varies seasonally. Observations of aerosols at island sites, which are commonly used as diagnostics of continental influences, may be misleading because they do not account for influences at high altitude and because aerosols are efficiently scavenged by deposition during transport. The study of Pb-210 focuses on defining the residence times of submicron aerosols in the troposphere. Scavenging in wet convective updrafts is found to provide the dominant sink on a global scale

Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-12-31

This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-31

This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

Multi-scale dynamic modeling of atmospheric pollution in urban environment

International Nuclear Information System (INIS)

Thouron, Laetitia

2017-01-01

Urban air pollution has been identified as an important cause of health impacts, including premature deaths. In particular, ambient concentrations of gaseous pollutants such as nitrogen dioxide (NO 2 ) and particulate matter (PM10 and PM2.5) are regulated, which means that emission reduction strategies must be put in place to reduce these concentrations in places where the corresponding regulations are not respected. Besides, air pollution can contribute to the contamination of other media, for example through the contribution of atmospheric deposition to runoff contamination. The multifactorial and multi-scale aspects of urban make the pollution sources difficult to identify. Indeed, the urban environment is a heterogeneous space characterized by complex architectural structures (old buildings alongside a more modern building, residential, commercial, industrial zones, roads, etc.), non-uniform atmospheric pollutant emissions and therefore the population exposure to pollution is variable in space and time. The modeling of urban air pollution aims to understand the origin of pollutants, their spatial extent and their concentration/deposition levels. Some pollutants have long residence times and can stay several weeks in the atmosphere (PM2.5) and therefore be transported over long distances, while others are more local (NO x in the vicinity of traffic). The spatial distribution of a pollutant will therefore depend on several factors, and in particular on the surfaces encountered. Air quality depends strongly on weather, buildings (canyon-street) and emissions. The aim of this thesis is to address some of these aspects by modeling: (1) urban background pollution with a transport-chemical model (Polyphemus / POLAIR3D), which makes it possible to estimate atmospheric pollutants by type of urban surfaces (roofs, walls and roadways), (2) street-level pollution by explicitly integrating the effects of the building in a three-dimensional way with a multi-scale model of

Nuclear analytical techniques applied to the large scale measurements of atmospheric aerosols in the amazon region

International Nuclear Information System (INIS)

Gerab, Fabio

1996-03-01

This work presents the characterization of the atmosphere aerosol collected in different places of the Amazon Basin. We studied both the biogenic emission from the forest and the particulate material which is emitted to the atmosphere due to the large scale man-made burning during the dry season. The samples were collected during a three year period at two different locations in the Amazon, namely the Alta Floresta (MT) and Serra do Navio (AP) regions, using stacked unit filters. These regions represent two different atmospheric compositions: the aerosol is dominated by the forest natural biogenic emission at Serra do Navio, while at Alta Floresta it presents an important contribution from the man-made burning during the dry season. At Alta Floresta we took samples in gold in order to characterize mercury emission to the atmosphere related to the gold prospection activity in Amazon. Airplanes were used for aerosol sampling during the 1992 and 1993 dry seasons to characterize the atmospheric aerosol contents from man-made burning in large Amazonian areas. The samples were analyzed using several nuclear analytic techniques: Particle Induced X-ray Emission for the quantitative analysis of trace elements with atomic number above 11; Particle Induced Gamma-ray Emission for the quantitative analysis of Na; and Proton Microprobe was used for the characterization of individual particles of the aerosol. Reflectancy technique was used in the black carbon quantification, gravimetric analysis to determine the total atmospheric aerosol concentration and Cold Vapor Atomic Absorption Spectroscopy for quantitative analysis of mercury in the particulate from the Alta Floresta gold shops. Ionic chromatography was used to quantify ionic contents of aerosols from the fine mode particulate samples from Serra do Navio. Multivariate statistical analysis was used in order to identify and characterize the sources of the atmospheric aerosol present in the sampled regions. (author)

Regional climate model sensitivity to domain size

Science.gov (United States)

Leduc, Martin; Laprise, René

2009-05-01

Regional climate models are increasingly used to add small-scale features that are not present in their lateral boundary conditions (LBC). It is well known that the limited area over which a model is integrated must be large enough to allow the full development of small-scale features. On the other hand, integrations on very large domains have shown important departures from the driving data, unless large scale nudging is applied. The issue of domain size is studied here by using the “perfect model” approach. This method consists first of generating a high-resolution climatic simulation, nicknamed big brother (BB), over a large domain of integration. The next step is to degrade this dataset with a low-pass filter emulating the usual coarse-resolution LBC. The filtered nesting data (FBB) are hence used to drive a set of four simulations (LBs for Little Brothers), with the same model, but on progressively smaller domain sizes. The LB statistics for a climate sample of four winter months are compared with BB over a common region. The time average (stationary) and transient-eddy standard deviation patterns of the LB atmospheric fields generally improve in terms of spatial correlation with the reference (BB) when domain gets smaller. The extraction of the small-scale features by using a spectral filter allows detecting important underestimations of the transient-eddy variability in the vicinity of the inflow boundary, which can penalize the use of small domains (less than 100 × 100 grid points). The permanent “spatial spin-up” corresponds to the characteristic distance that the large-scale flow needs to travel before developing small-scale features. The spin-up distance tends to grow in size at higher levels in the atmosphere.

Multi-Year Estimates of Regional Alaskan Net CO2 Exchange: Constraining a Remote-Sensing Based Model with Aircraft Observations

Science.gov (United States)

Lindaas, J.; Commane, R.; Luus, K. A.; Chang, R. Y. W.; Miller, C. E.; Dinardo, S. J.; Henderson, J.; Mountain, M. E.; Karion, A.; Sweeney, C.; Miller, J. B.; Lin, J. C.; Daube, B. C.; Pittman, J. V.; Wofsy, S. C.

2014-12-01

The Alaskan region has historically been a sink of atmospheric CO2, but permafrost currently stores large amounts of carbon that are vulnerable to release to the atmosphere as northern high-latitudes continue to warm faster than the global average. We use aircraft CO2 data with a remote-sensing based model driven by MODIS satellite products and validated by CO2 flux tower data to calculate average daily CO2 fluxes for the region of Alaska during the growing seasons of 2012 and 2013. Atmospheric trace gases were measured during CARVE (Carbon in Arctic Reservoirs Vulnerability Experiment) aboard the NASA Sherpa C-23 aircraft. For profiles along the flight track, we couple the Weather Research and Forecasting (WRF) model with the Stochastic Time-Inverted Lagrangian Transport (STILT) model, and convolve these footprints of surface influence with our remote-sensing based model, the Polar Vegetation Photosynthesis Respiration Model (PolarVPRM). We are able to calculate average regional fluxes for each month by minimizing the difference between the data and model column integrals. Our results provide a snapshot of the current state of regional Alaskan growing season net ecosystem exchange (NEE). We are able to begin characterizing the interannual variation in Alaskan NEE and to inform future refinements in process-based modeling that will produce better estimates of past, present, and future pan-Arctic NEE. Understanding if/when/how the Alaskan region transitions from a sink to a source of CO2 is crucial to predicting the trajectory of future climate change.

The Middle Miocene climate as modelled in an atmosphere-ocean-biosphere model

Directory of Open Access Journals (Sweden)

M. Krapp

2011-11-01

Full Text Available We present simulations with a coupled atmosphere-ocean-biosphere model for the Middle Miocene 15 million years ago. The model is insofar more consistent than previous models because it captures the essential interactions between ocean and atmosphere and between atmosphere and vegetation. The Middle Miocene topography, which alters both large-scale ocean and atmospheric circulations, causes a global warming of 0.7 K compared to present day. Higher than present-day CO₂ levels of 480 and 720 ppm cause a global warming of 2.8 and 4.9 K. The associated water vapour feedback enhances the greenhouse effect which leads to a polar amplification of the warming. These results suggest that higher than present-day CO₂ levels are necessary to drive the warm Middle Miocene climate, also because the dynamic vegetation model simulates a denser vegetation which is in line with fossil records. However, we do not find a flatter than present-day equator-to-pole temperature gradient as has been suggested by marine and terrestrial proxies. Instead, a compensation between atmospheric and ocean heat transport counteracts the flattening of the temperature gradient. The acclaimed role of the large-scale ocean circulation in redistributing heat cannot be supported by our results. Including full ocean dynamics, therefore, does not solve the problem of the flat temperature gradient during the Middle Miocene.

SEMI-EMPIRICAL MODELING OF THE PHOTOSPHERE, CHROMOPSHERE, TRANSITION REGION, AND CORONA OF THE M-DWARF HOST STAR GJ 832

Energy Technology Data Exchange (ETDEWEB)

Fontenla, J. M. [NorthWest Research Associates, Boulder, CO 80301 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, Boulder, CO 80309-0440 (United States); Witbrod, Jesse [University of Colorado Boulder, CO 80309 (United States); France, Kevin [LASP, University of Colorado Boulder, CO 80309-0600 (United States); Buccino, A.; Mauas, Pablo; Vieytes, Mariela [Instituto de Astronomía y Física del Espacio (CONICET-UBA), C.C. 67, Sucursal 28, C1428EHA, Buenos Aires (Argentina); Walkowicz, Lucianne M., E-mail: johnf@digidyna.com, E-mail: jlinsky@jila.colorado.edu, E-mail: jesse.witbrod@colorado.edu, E-mail: kevin.france@lasp.colorado.edu, E-mail: abuccino@iafe.uba.ar, E-mail: pablo@iafe.uba.ar, E-mail: mariela@iafe.uba.ar, E-mail: LWalkowicz@adlerplanetarium.org [The Adler Planetarium, Chicago, IL 60605 (United States)

2016-10-20

Stellar radiation from X-rays to the visible provides the energy that controls the photochemistry and mass loss from exoplanet atmospheres. The important extreme ultraviolet (EUV) region (10–91.2 nm) is inaccessible and should be computed from a reliable stellar model. It is essential to understand the formation regions and physical processes responsible for the various stellar emission features to predict how the spectral energy distribution varies with age and activity levels. We compute a state-of-the-art semi-empirical atmospheric model and the emergent high-resolution synthetic spectrum of the moderately active M2 V star GJ 832 as the first of a series of models for stars with different activity levels. We construct a one-dimensional simple model for the physical structure of the star’s chromosphere, chromosphere-corona transition region, and corona using non-LTE radiative transfer techniques and many molecular lines. The synthesized spectrum for this model fits the continuum and lines across the UV-to-optical spectrum. Particular emphasis is given to the emission lines at wavelengths that are shorter than 300 nm observed with the Hubble Space Telescope , which have important effects on the photochemistry of the exoplanet atmospheres. The FUV line ratios indicate that the transition region of GJ 832 is more biased to hotter material than that of the quiet Sun. The excellent agreement of our computed EUV luminosity with that obtained by two other techniques indicates that our model predicts reliable EUV emission from GJ 832. We find that the unobserved EUV flux of GJ 832, which heats the outer atmospheres of exoplanets and drives their mass loss, is comparable to the active Sun.

Model study of atmospheric transport using carbon 14 and strontium 90 as inert tracers

Science.gov (United States)

Kinnison, D. E.; Johnston, H. S.; Wuebbles, D. J.

1994-10-01

The observed excess carbon 14 in the atmosphere from 1963 to 1970 provides unique, but limited, data up to an altitude of about 35 km for testing the air motions calculated by 11 multidimensional atmospheric models. Strontium 90 measurements in the atmosphere from 1964 to mid-1967 provide data that have more latitude coverage than those of carbon 14 and are useful for testing combined models of air motions and aerosol settling. Model calculations for carbon 14 begin at October 1963, 9 months after the conclusion of the nuclear bomb tests; the initial conditions for the calculations are derived by three methods, each of which agrees fairly well with measured carbon 14 in October 1963 and each of which has widely different values in regions of the stratosphere where there were no carbon 14 measurements. The model results are compared to the stratospheric measurements, not as if the observed data were absolute standards, but in an effort to obtain new insight about the models and about the atmosphere. The measured carbon 14 vertical profiles at 31°N are qualitatively different from all of the models; the measured vertical profiles show a maximum mixing ratio in the altitude range of 20 to 25 km from October 1963 through July 1966, but all modeled profiles show mixing ratio maxima that increase in altitude from 20 km in October 1963 to greater than 40 km by April 1966. Both carbon 14 and strontium 90 data indicate that the models differ substantially among themselves with respect to stratosphere-troposphere exchange rate, but the modeled carbon 14 stratospheric residence times indicate that differences among the models are small with respect to transport rate between the middle stratosphere and the lower stratosphere. Strontium 90 data indicate that aerosol settling is important up to at least 35 km altitude. Relative to the measurements, about three quarters of the models transport carbon 14 from the lower stratosphere to the troposphere too rapidly, and all models

A Mercury Model of Atmospheric Transport

Energy Technology Data Exchange (ETDEWEB)

Christensen, Alex B. [Oregon State Univ., Corvallis, OR (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chodash, Perry A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Procassini, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2018-01-19

Using the particle transport code Mercury, accurate models were built of the two sources used in Operation BREN, a series of radiation experiments performed by the United States during the 1960s. In the future, these models will be used to validate Mercury’s ability to simulate atmospheric transport.

Influence of ENSO on Regional Indian Summer Monsoon Precipitation—Local Atmospheric Influences or Remote Influence from Pacific

Directory of Open Access Journals (Sweden)

Indrani Roy

2016-02-01

Full Text Available Using CMIP5 model outputs in different El Niño-Southern Oscillation (ENSO phases, this work investigates the indicator that could be used as an Index to characterise regional Indian Summer Monsoon (ISM precipitation. Dividing the Indian subcontinent into five arbitrarily chosen regions, viz. Central North East (CNE (18°N–31°N, 86°E–75°E, Hilly (H (28°N–38°N, 85°E–70°E, North West (NW (21°N–31°N, 79°E–67°E, North East (NE (21°N–31°N, 86°E–97°E and Southern India (S (18°N–7°N, 73°E–85°E, local wind field and remote influences from the tropical Pacific are considered to improve understanding of regional monsoon rainfall. Results are also compared with observations/reanalysis data to pinpoint areas of shortcomings and agreements. Model results suggest that regional wind velocity, viz. meridional wind component (V at 850 mb level (V850 and zonal component at 200 mb (U200 and 850 mb (U850 can yield better estimation of local precipitation in regions CNE, H and NW, agreeing well with earlier proposed monsoon Indices. Such observations are independent of different subcategories of ENSO phases and models show good correspondence with observations. Analyses with V at 200 mb (V200 indicate circulation of the upper branch of Hadley cells in regions CNE and S, though suggest the best agreement among models in comparison with other fields, but there are some deviations from observations, indicating a missing mechanism in the models. Using models, this study identified the best parameter in different regions that could be used for the regional monsoon Index, irrespective of various ENSO subcategories; for CNE it is the U200, for H it is U200 and U850, and for NW it is U850. The current analysis, however, fails to indicate anything clearly about the NE region. When focusing on the remote influence from the eastern Pacific region, it is found that atmospheric contribution to regional ISM precipitation fails to indicate

On atmospheric stability in the dynamic wake meandering model

DEFF Research Database (Denmark)

Keck, Rolf-Erik; de Mare, Martin Tobias; Churchfield, Matthew J.

2014-01-01

The present study investigates a new approach for capturing the effects of atmospheric stability on wind turbine wake evolution and wake meandering by using the dynamic wake meandering model. The most notable impact of atmospheric stability on the wind is the changes in length and velocity scales...... spectra and applied to the dynamic wake meandering model to capture the correct wake meandering behaviour. The ambient turbulence in all stability classes is generated using the Mann turbulence model, where the effects of non-neutral atmospheric stability are approximated by the selection of input...... in the computational domain. The changes in the turbulent length scales due to the various atmospheric stability states impact the wake meandering characteristics and thus the power generation by the individual turbines. The proposed method is compared with results from both large-eddy simulation coupled...

Alleviating tropical Atlantic sector biases in the Kiel climate model by enhancing horizontal and vertical atmosphere model resolution: climatology and interannual variability

Science.gov (United States)

Harlaß, Jan; Latif, Mojib; Park, Wonsun

2018-04-01

We investigate the quality of simulating tropical Atlantic (TA) sector climatology and interannual variability in integrations of the Kiel climate model (KCM) with varying atmosphere model resolution. The ocean model resolution is kept fixed. A reasonable simulation of TA sector annual-mean climate, seasonal cycle and interannual variability can only be achieved at sufficiently high horizontal and vertical atmospheric resolution. Two major reasons for the improvements are identified. First, the western equatorial Atlantic westerly surface wind bias in spring can be largely eliminated, which is explained by a better representation of meridional and especially vertical zonal momentum transport. The enhanced atmospheric circulation along the equator in turn greatly improves the thermal structure of the upper equatorial Atlantic with much reduced warm sea surface temperature (SST) biases. Second, the coastline in the southeastern TA and steep orography are better resolved at high resolution, which improves wind structure and in turn reduces warm SST biases in the Benguela upwelling region. The strongly diminished wind and SST biases at high atmosphere model resolution allow for a more realistic latitudinal position of the intertropical convergence zone. Resulting stronger cross-equatorial winds, in conjunction with a shallower thermocline, enable a rapid cold tongue development in the eastern TA in boreal spring. This enables simulation of realistic interannual SST variability and its seasonal phase locking in the KCM, which primarily is the result of a stronger thermocline feedback. Our findings suggest that enhanced atmospheric resolution, both vertical and horizontal, could be a key to achieving more realistic simulation of TA climatology and interannual variability in climate models.

Accelerating Atmospheric Modeling Through Emerging Multi-core Technologies

OpenAIRE

Linford, John Christian

2010-01-01

The new generations of multi-core chipset architectures achieve unprecedented levels of computational power while respecting physical and economical constraints. The cost of this power is bewildering program complexity. Atmospheric modeling is a grand-challenge problem that could make good use of these architectures if they were more accessible to the average programmer. To that end, software tools and programming methodologies that greatly simplify the acceleration of atmospheric modeling...

Learning About Climate and Atmospheric Models Through Machine Learning

Science.gov (United States)

Lucas, D. D.

2017-12-01

From the analysis of ensemble variability to improving simulation performance, machine learning algorithms can play a powerful role in understanding the behavior of atmospheric and climate models. To learn about model behavior, we create training and testing data sets through ensemble techniques that sample different model configurations and values of input parameters, and then use supervised machine learning to map the relationships between the inputs and outputs. Following this procedure, we have used support vector machines, random forests, gradient boosting and other methods to investigate a variety of atmospheric and climate model phenomena. We have used machine learning to predict simulation crashes, estimate the probability density function of climate sensitivity, optimize simulations of the Madden Julian oscillation, assess the impacts of weather and emissions uncertainty on atmospheric dispersion, and quantify the effects of model resolution changes on precipitation. This presentation highlights recent examples of our applications of machine learning to improve the understanding of climate and atmospheric models. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Modelling Chemical Patterns of Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) in the Iberian Peninsula

Science.gov (United States)

Ratola, Nuno; Jiménez-Guerrero, Pedro

2013-04-01

(CHIMERE), providing information about the levels and transport patterns (e.g. dispersion) of PAHs in the area. The justification for this study is the gaps still existing in the awareness of the life cycles of such and related contaminants. The comparison of the levels on a regional and on a European scale will enable the strong enhancement of the knowledge available in the current scientific literature for studies of atmospheric chemistry and transport of trans-boundary pollutants, which is scarce (and even more if we consider its model validation against experimental data).