WorldWideScience

Sample records for maritime convective clouds

  1. Convective Cloud and Rainfall Processes Over the Maritime Continent: Simulation and Analysis of the Diurnal Cycle

    Science.gov (United States)

    Gianotti, Rebecca L.

    The Maritime Continent experiences strong moist convection, which produces significant rainfall and drives large fluxes of heat and moisture to the upper troposphere. Despite the importance of these processes to global circulations, current predictions of climate change over this region are still highly uncertain, largely due to inadequate representation of the diurnally-varying processes related to convection. In this work, a coupled numerical model of the land-atmosphere system (RegCM3-IBIS) is used to investigate how more physically-realistic representations of these processes can be incorporated into large-scale climate models. In particular, this work improves simulations of convective-radiative feedbacks and the role of cumulus clouds in mediating the diurnal cycle of rainfall. Three key contributions are made to the development of RegCM3-IBIS. Two pieces of work relate directly to the formation and dissipation of convective clouds: a new representation of convective cloud cover, and a new parameterization of convective rainfall production. These formulations only contain parameters that can be directly quantified from observational data, are independent of model user choices such as domain size or resolution, and explicitly account for subgrid variability in cloud water content and nonlinearities in rainfall production. The third key piece of work introduces a new method for representation of cloud formation within the boundary layer. A comprehensive evaluation of the improved model was undertaken using a range of satellite-derived and ground-based datasets, including a new dataset from Singapore's Changi airport that documents diurnal variation of the local boundary layer height. The performance of RegCM3-IBIS with the new formulations is greatly improved across all evaluation metrics, including cloud cover, cloud liquid water, radiative fluxes and rainfall, indicating consistent improvement in physical realism throughout the simulation. This work

  2. Scale analysis of convective clouds

    Directory of Open Access Journals (Sweden)

    Micha Gryschka

    2008-12-01

    Full Text Available The size distribution of cumulus clouds due to shallow and deep convection is analyzed using satellite pictures, LES model results and data from the German rain radar network. The size distributions found can be described by simple power laws as has also been proposed for other cloud data in the literature. As the observed precipitation at ground stations is finally determined by cloud numbers in an area and individual sizes and rain rates of single clouds, the cloud size distributions might be used for developing empirical precipitation forecasts or for validating results from cloud resolving models being introduced to routine weather forecasts.

  3. Large-eddy simulation of maritime deep tropical convection

    Directory of Open Access Journals (Sweden)

    Peter A Bogenschutz

    2009-12-01

    Full Text Available This study represents an attempt to apply Large-Eddy Simulation (LES resolution to simulate deep tropical convection in near equilibrium for 24 hours over an area of about 205 x 205 km2, which is comparable to that of a typical horizontal grid cell in a global climate model. The simulation is driven by large-scale thermodynamic tendencies derived from mean conditions during the GATE Phase III field experiment. The LES uses 2048 x 2048 x 256 grid points with horizontal grid spacing of 100 m and vertical grid spacing ranging from 50 m in the boundary layer to 100 m in the free troposphere. The simulation reaches a near equilibrium deep convection regime in 12 hours. The simulated vertical cloud distribution exhibits a trimodal vertical distribution of deep, middle and shallow clouds similar to that often observed in Tropics. A sensitivity experiment in which cold pools are suppressed by switching off the evaporation of precipitation results in much lower amounts of shallow and congestus clouds. Unlike the benchmark LES where the new deep clouds tend to appear along the edges of spreading cold pools, the deep clouds in the no-cold-pool experiment tend to reappear at the sites of the previous deep clouds and tend to be surrounded by extensive areas of sporadic shallow clouds. The vertical velocity statistics of updraft and downdraft cores below 6 km height are compared to aircraft observations made during GATE. The comparison shows generally good agreement, and strongly suggests that the LES simulation can be used as a benchmark to represent the dynamics of tropical deep convection on scales ranging from large turbulent eddies to mesoscale convective systems. The effect of horizontal grid resolution is examined by running the same case with progressively larger grid sizes of 200, 400, 800, and 1600 m. These runs show a reasonable agreement with the benchmark LES in statistics such as convective available potential energy, convective inhibition

  4. Tracking the MJO Convection and its Impact on the Diurnal Cycle over the Maritime Continent Using Satellite Observations

    Science.gov (United States)

    Kerns, B. W.; Chen, S. S.

    2017-12-01

    The Indo-Pacific Maritime Continent (MC) is the most active convection center in the tropics, and the most important modes of variability are the diurnal cycle and the Madden-Julian Oscillation (MJO). Previous studies have shown that the MC has strong diurnal variability compared with the rest of the tropics, and the diurnal cycle of convection over the MC is amplified during the passage of an MJO. One outstanding science question is how the passage of the active MJO affects the diurnal cycle. The atmospheric, upper ocean, and land surface forcing factors contributing to the diurnal cycle need to be clarified. In order to address this, large scale precipitation tracking (LPT) is used to identify MJO active and suppressed periods for 2000-2015. To document the diurnal cycle of convection during the active and suppressed periods, TRMM/GPM and mesoscale cloud cluster tracking are used. Finally, the LPT tracking is used to composite the satellite-estimated surface wind, humidity, temperature, cloud cover, and soil moisture over the islands for active versus suppressed MJO periods. In active MJO periods, the diurnal convection in the surrounding marginal seas is enhanced and the diurnal convection over land is decreased. The islands of the MC have greater soil moisture, more cloud cover, and do not warm up as much during the day, leading to a weaker afternoon maximum over land. But how is nocturnal convection over the sea increased? The largest, most mature convective cloud systems are found over the marginal seas in the early morning. This is hypothesized to mainly be a consequence of the longer life cycle of convective systems in the favorable large-scale active MJO. The propagation of the MJO across the MC is facilitated by the enhanced nocturnal deep convection over the sea. In contrast, In the suppressed period the convection is mostly daytime forced convection over land which is locked to the terrain.

  5. Deep convective clouds at the tropopause

    Directory of Open Access Journals (Sweden)

    H. H. Aumann

    2011-02-01

    Full Text Available Data from the Atmospheric Infrared Sounder (AIRS on the EOS Aqua spacecraft each day show tens of thousands of Cold Clouds (CC in the tropical oceans with 10 μm window channel brightness temperatures colder than 225 K. These clouds represent a mix of cold anvil clouds and Deep Convective Clouds (DCC. This mix can be separated by computing the difference between two channels, a window channel and a channel with strong CO2 absorption: for some cold clouds this difference is negative, i.e. the spectra for some cold clouds are inverted. We refer to cold clouds with spectra which are more than 2 K inverted as DCCi2. Associated with DCCi2 is a very high rain rate and a local upward displacement of the tropopause, a cold "bulge", which can be seen directly in the brightness temperatures of AIRS and Advanced Microwave Sounding Unit (AMSU temperature sounding channels in the lower stratosphere. The very high rain rate and the local distortion of the tropopause indicate that DCCi2 objects are associated with severe storms. Significant long-term trends in the statistical properties of DCCi2 could be interesting indicators of climate change. While the analysis of the nature and physical conditions related to DCCi2 requires hyperspectral infrared and microwave data, the identification of DCCi2 requires only one good window channel and one strong CO2 sounding channel. This suggests that improved identification of severe storms with future advanced geostationary satellites could be accomplished with the addition of one or two narrow band channels.

  6. Environments for online maritime simulators with cloud computing capabilities

    Science.gov (United States)

    Raicu, Gabriel; Raicu, Alexandra

    2016-12-01

    This paper presents the cloud computing environments, network principles and methods for graphical development in realistic naval simulation, naval robotics and virtual interactions. The aim of this approach is to achieve a good simulation quality in large networked environments using open source solutions designed for educational purposes. Realistic rendering of maritime environments requires near real-time frameworks with enhanced computing capabilities during distance interactions. E-Navigation concepts coupled with the last achievements in virtual and augmented reality will enhance the overall experience leading to new developments and innovations. We have to deal with a multiprocessing situation using advanced technologies and distributed applications using remote ship scenario and automation of ship operations.

  7. Dynamics of Clouds and Mesoscale Circulations over the Maritime Continent

    Science.gov (United States)

    Jin, Y.; Wang, S.; Xian, P.; Reid, J. S.; Nachamkin, J.

    2010-12-01

    understanding of the effects of aerosol particles on maritime clouds. The detailed analysis will be presented at the conference.

  8. The impact of parametrized convection on cloud feedback

    Science.gov (United States)

    Webb, Mark J.; Lock, Adrian P.; Bretherton, Christopher S.; Bony, Sandrine; Cole, Jason N. S.; Idelkadi, Abderrahmane; Kang, Sarah M.; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C.; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D.; Zhao, Ming

    2015-01-01

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud

  9. The interaction between deep convective clouds and their environment

    NARCIS (Netherlands)

    Böing, S.J.

    2014-01-01

    Deep convective clouds play a key role in tropical weather patterns, summertime rainfall, and the global transport of energy from the tropics to higher latitudes. Current weather and climate models struggle to realistically represent the development and behavior of these clouds. Both the timing of

  10. Models of surface convection and dust clouds in brown dwarfs

    International Nuclear Information System (INIS)

    Freytag, B; Allard, F; Ludwig, H-G; Homeier, D; Steffen, M

    2008-01-01

    The influence of dust grains on the atmospheres of brown dwarfs is visible in observed spectra. To investigate what prevents the dust grains from falling down, or how fresh condensable material is mixed up in the atmosphere to allow new grains to form, we performed 2D radiation-hydrodynamics simulations with CO5BOLD of the upper part of the convection zone and the atmosphere containing the dust cloud layers. We find that unlike in models of Cepheids, the convective overshoot does not play a major role. Instead, the mixing in the dust clouds is controlled by gravity waves.

  11. Statistical thermodynamics and the size distributions of tropical convective clouds.

    Science.gov (United States)

    Garrett, T. J.; Glenn, I. B.; Krueger, S. K.; Ferlay, N.

    2017-12-01

    Parameterizations for sub-grid cloud dynamics are commonly developed by using fine scale modeling or measurements to explicitly resolve the mechanistic details of clouds to the best extent possible, and then to formulating these behaviors cloud state for use within a coarser grid. A second is to invoke physical intuition and some very general theoretical principles from equilibrium statistical thermodynamics. This second approach is quite widely used elsewhere in the atmospheric sciences: for example to explain the heat capacity of air, blackbody radiation, or even the density profile or air in the atmosphere. Here we describe how entrainment and detrainment across cloud perimeters is limited by the amount of available air and the range of moist static energy in the atmosphere, and that constrains cloud perimeter distributions to a power law with a -1 exponent along isentropes and to a Boltzmann distribution across isentropes. Further, the total cloud perimeter density in a cloud field is directly tied to the buoyancy frequency of the column. These simple results are shown to be reproduced within a complex dynamic simulation of a tropical convective cloud field and in passive satellite observations of cloud 3D structures. The implication is that equilibrium tropical cloud structures can be inferred from the bulk thermodynamic structure of the atmosphere without having to analyze computationally expensive dynamic simulations.

  12. Midlatitude Continental Convective Clouds Experiment (MC3E)

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

    2010-04-01

    Convective processes play a critical role in the Earth’s energy balance through the redistribution of heat and moisture in the atmosphere and subsequent impacts on the hydrologic cycle. Global observation and accurate representation of these processes in numerical models is vital to improving our current understanding and future simulations of Earth’s climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales that are associated with convective and stratiform precipitation processes; therefore, they must turn to parameterization schemes to represent these processes. In turn, the physical basis for these parameterization schemes needs to be evaluated for general application under a variety of atmospheric conditions. Analogously, space-based remote sensing algorithms designed to retrieve related cloud and precipitation information for use in hydrological, climate, and numerical weather prediction applications often rely on physical “parameterizations” that reliably translate indirectly related instrument measurements to the physical quantity of interest (e.g., precipitation rate). Importantly, both spaceborne retrieval algorithms and model convective parameterization schemes traditionally rely on field campaign data sets as a basis for evaluating and improving the physics of their respective approaches. The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the April–May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration’s (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States

  13. Relationships between radiation, clouds, and convection during DYNAMO

    Science.gov (United States)

    Ciesielski, Paul E.; Johnson, Richard H.; Jiang, Xianan; Zhang, Yunyan; Xie, Shaocheng

    2017-03-01

    The relationships between radiation, clouds, and convection on an intraseasonal time scale are examined with data taken during the Dynamics of the Madden-Julian Oscillation (MJO) field campaign. Specifically, column-net, as well as vertical profiles of radiative heating rates, computed over Gan Island in the central Indian Ocean (IO) are used along with an objective analysis of large-scale fields to examine three MJO events that occurred during the 3 month period (October to December 2011) over this region. Longwave (LW) and shortwave radiative heating rates exhibit tilted structures, reflecting radiative effects associated with the prevalence of shallow cumulus during the dry, suppressed MJO phase followed by increasing deep convection leading into the active phase. As the convection builds going into the MJO active phase, there are increasingly top-heavy anomalous radiative heating rates while the column-net radiative cooling rate progressively decreases. Temporal fluctuations in the cloud radiative forcing, being quite sensitive to changes in high cloudiness, are dominated by LW effects with an intraseasonal variation of 0.4-0.6 K/d. While both the water vapor and cloud fields are inextricably linked, it appears that the tilted radiative structures are more related to water vapor effects. The intraseasonal variation of column-net radiative heating enhances the convective signal in the mean by 20% with a minimum in this enhancement 10 days prior to peak MJO rainfall and maximum 7 days after. This suggests that as MJO convective envelope weakens over the central IO, cloud-radiative feedbacks help maintain the mature MJO as it moves eastward.

  14. Frequency of Deep Convective Clouds and Global Warming

    Science.gov (United States)

    Aumann, Hartmut H.; Teixeira, Joao

    2008-01-01

    This slide presentation reviews the effect of global warming on the formation of Deep Convective Clouds (DCC). It concludes that nature responds to global warming with an increase in strong convective activity. The frequency of DCC increases with global warming at the rate of 6%/decade. The increased frequency of DCC with global warming alone increases precipitation by 1.7%/decade. It compares the state of the art climate models' response to global warming, and concludes that the parametrization of climate models need to be tuned to more closely emulate the way nature responds to global warming.

  15. Cloud's Center of Gravity – a compact approach to analyze convective cloud development

    Directory of Open Access Journals (Sweden)

    I. Koren

    2009-01-01

    Full Text Available As cloud resolving models become more detailed, with higher resolution outputs, it is often complicated to isolate the physical processes that control the cloud attributes. Moreover, due to the high dimensionality and complexity of the model output, the analysis and interpretation of the results can be very complicated. Here we suggest a novel approach to convective cloud analysis that yields more insight into the physical and temporal evolution of clouds, and is compact and efficient. The different (3-D cloud attributes are weighted and projected onto a single point in space and in time, that has properties of, or similar to, the Center Of Gravity (COG. The location, magnitude and spread of this variable are followed in time. The implications of the COG approach are demonstrated for a study of aerosol effects on a warm convective cloud. We show that in addition to reducing dramatically the dimensionality of the output, such an approach often enhances the signal, adds more information, and makes the physical description of cloud evolution clearer, allowing unambiguous comparison of clouds evolving in different environmental conditions. This approach may also be useful for analysis of cloud data retrieved from surface or space-based cloud radars.

  16. The Mechanism of First Raindrops Formation in Deep Convective Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Khain, Alexander; Prabha, Thara; Benmoshe, Nir; Pandithurai, G.; Ovchinnikov, Mikhail

    2013-08-22

    The formation of first raindrops in deep convective clouds is investigated. A combination of observational data analysis and 2-D and 3-D numerical bin microphysical simulations of deep convective clouds suggests that the first raindrops form at the top of undiluted or slightly diluted cores. It is shown that droplet size distributions in these regions are wider and contain more large droplets than in diluted volumes. The results of the study indicate that the initial raindrop formation is determined by the basic microphysical processes within ascending adiabatic volumes. It allows one to predict the height of the formation of first raindrops considering the processes of nucleation, diffusion growth and collisions. The results obtained in the study explain observational results reported by Freud and Rosenfeld (2012) according to which the height of first raindrop formation depends linearly on the droplet number concentration at cloud base. The results also explain why a simple adiabatic parcel model can reproduce this dependence. The present study provides a physical basis for retrieval algorithms of cloud microphysical properties and aerosol properties using satellites proposed by Rosenfeld et al. ( 2012). The study indicates that the role of mixing and entrainment in the formation of the first raindrops is not of crucial importance. It is also shown that low variability of effective and mean volume radii along horizontal traverses, as regularly observed by in situ measurements, can be simulated by high-resolution cloud models, in which mixing is parameterized by a traditional 1.5 order turbulence closure scheme.

  17. Vertical profiles of droplet effective radius in shallow convective clouds

    Directory of Open Access Journals (Sweden)

    S. Zhang

    2011-05-01

    Full Text Available Conventional satellite retrievals can only provide information on cloud-top droplet effective radius (re. Given the fact that cloud ensembles in a satellite snapshot have different cloud-top heights, Rosenfeld and Lensky (1998 used the cloud-top height and the corresponding cloud-top re from the cloud ensembles in the snapshot to construct a profile of re representative of that in the individual clouds. This study investigates the robustness of this approach in shallow convective clouds based on results from large-eddy simulations (LES for clean (aerosol mixing ratio Na = 25 mg−1, intermediate (Na = 100 mg−1, and polluted (Na = 2000 mg−1 conditions. The cloud-top height and the cloud-top re from the modeled cloud ensembles are used to form a constructed re profile, which is then compared to the in-cloud re profiles. For the polluted and intermediate cases where precipitation is negligible, the constructed re profiles represent the in-cloud re profiles fairly well with a low bias (about 10 %. The method used in Rosenfeld and Lensky (1998 is therefore validated for nonprecipitating shallow cumulus clouds. For the clean, drizzling case, the in-cloud re can be very large and highly variable, and quantitative profiling based on cloud-top re is less useful. The differences in re profiles between clean and polluted conditions derived in this manner are however, distinct. This study also investigates the subadiabatic characteristics of the simulated cumulus clouds to reveal the effect of mixing on re and its evolution. Results indicate that as polluted and moderately polluted clouds develop into their decaying stage, the subadiabatic fraction

  18. The relationships between precipitation, convective cloud and tropical cyclone intensity change

    Science.gov (United States)

    Ruan, Z.; Wu, Q.

    2017-12-01

    Using 16 years precipitation, brightness temperature (IR BT) data and tropical cyclone (TC) information, this study explores the relationship between precipitation, convective cloud and tropical cyclone (TC) intensity change in the Western North Pacific Ocean. It is found that TC intensity has positive relation with TC precipitation. TC precipitation increases with increased TC intensity. Based on the different phase of diurnal cycle, convective TC clouds were divided into very cold deep convective clouds (IR BTs<208K) and cold high clouds (208K

  19. Midlatitude Continental Convective Clouds Experiment (MC3E)

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

    2010-04-10

    The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the April–May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration’s (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that have never before been available.

  20. Impact of Aerosols on Convective Clouds and Precipitation

    Science.gov (United States)

    Tao, Wei-Kuo; Chen, Jen-Ping; Li, Zhanqing; Wang, Chien; Zhang, Chidong; Li, Xiaowen

    2012-01-01

    Aerosols are a critical.factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosols have a major impact on the dynamics, microphysics, and electrification properties of continental mixed-phase convective clouds. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing a significant source of cloud condensation nuclei (CCN). Such pollution . effects on precipitation potentially have enormous climatic consequences both in terms of feedbacks involving the land surface via rainfall as well as the surface energy budget and changes in latent heat input to the atmosphere. Basically, aerosol concentrations can influence cloud droplet size distributions, the warm-rain process, the cold-rain process, cloud-top heights, the depth of the mixed-phase region, and the occurrence of lightning. Recently, many cloud resolution models (CRMs) have been used to examine the role of aerosols on mixed-phase convective clouds. These modeling studies have many differences in terms of model configuration (two- or three-dimensional), domain size, grid spacing (150-3000 m), microphysics (two-moment bulk, simple or sophisticated spectral-bin), turbulence (1st or 1.5 order turbulent kinetic energy (TKE)), radiation, lateral boundary conditions (i.e., closed, radiative open or cyclic), cases (isolated convection, tropical or midlatitude squall lines) and model integration time (e.g., 2.5 to 48 hours). Among these modeling studies, the most striking difference is that cumulative precipitation can either increase or decrease in response to higher concentrations of CCN. In this presentation, we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes. Specifically, this paper addresses the following topics

  1. Thermal structure of intense convective clouds derived from GPS radio occultations

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Randel, W. J.; Ho, S. -P.

    2012-01-01

    Thermal structure associated with deep convective clouds is investigated using Global Positioning System (GPS) radio occultation measurements. GPS data are insensitive to the presence of clouds, and provide high vertical resolution and high accuracy measurements to identify associated temperature...... behavior. Deep convective systems are identified using International Satellite Cloud Climatology Project (ISCCP) satellite data, and cloud tops are accurately measured using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIPSO) lidar observations; we focus on 53 cases of near-coincident GPS...

  2. Thermal structure of intense convective clouds derived from GPS radio occultations

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Randel, W. J.; Ho, S.-P.

    2011-01-01

    Thermal structure associated with deep convective clouds is investigated using Global Positioning System (GPS) radio occultation measurements. GPS data are insensitive to the presence of clouds, and provide high vertical resolution and high accuracy measurements to identify associated temperature...... behavior. Deep convective systems are identified using International Satellite Cloud Climatology Project (ISCCP) satellite data, and cloud tops are accurately measured using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIPSO) lidar observations; we focus on 53 cases of near-coincident GPS...

  3. A physically based algorithm for non-blackbody correction of the cloud top temperature for the convective clouds

    Science.gov (United States)

    Wang, C.; Luo, Z. J.; Chen, X.; Zeng, X.; Tao, W.; Huang, X.

    2012-12-01

    Cloud top temperature is a key parameter to retrieval in the remote sensing of convective clouds. Passive remote sensing cannot directly measure the temperature at the cloud tops. Here we explore a synergistic way of estimating cloud top temperature by making use of the simultaneous passive and active remote sensing of clouds (in this case, CloudSat and MODIS). Weighting function of the MODIS 11μm band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat retrievals and temperature and humidity profiles based on ECMWF ERA-interim reanalysis into a radiation transfer model. Among 19,699 tropical deep convective clouds observed by the CloudSat in 2008, the averaged effective emission level (EEL, where the weighting function attains its maximum) is at optical depth 0.91 with a standard deviation of 0.33. Furthermore, the vertical gradient of CloudSat radar reflectivity, an indicator of the fuzziness of convective cloud top, is linearly proportional to, d_{CTH-EEL}, the distance between the EEL of 11μm channel and cloud top height (CTH) determined by the CloudSat when d_{CTH-EEL}<0.6km. Beyond 0.6km, the distance has little sensitivity to the vertical gradient of CloudSat radar reflectivity. Based on these findings, we derive a formula between the fuzziness in the cloud top region, which is measurable by CloudSat, and the MODIS 11μm brightness temperature assuming that the difference between effective emission temperature and the 11μm brightness temperature is proportional to the cloud top fuzziness. This formula is verified using the simulated deep convective cloud profiles by the Goddard Cumulus Ensemble model. We further discuss the application of this formula in estimating cloud top buoyancy as well as the error characteristics of the radiative calculation within such deep-convective clouds.

  4. Improving Convection and Cloud Parameterization Using ARM Observations and NCAR Community Atmosphere Model CAM5

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guang J. [Univ. of California, San Diego, CA (United States)

    2016-11-07

    The fundamental scientific objectives of our research are to use ARM observations and the NCAR CAM5 to understand the large-scale control on convection, and to develop improved convection and cloud parameterizations for use in GCMs.

  5. Biomass Smoke Influences on Deep Convection during the 2011 Midlatitude Continental Convective Clouds Experiment (MC3E)

    Science.gov (United States)

    Dong, X.; Logan, T.; Xi, B.

    2015-12-01

    Three deep convective cloud cases were selected during the 2011 Mid-Latitude Continental Convective Clouds Experiment (MC3E). Although biomass burning smoke advected from Mexico and Central America was the dominant source of cloud condensation nuclei (CCN) for deep convective cloud formation, the 11 May, 20 May, and 23 May cases exhibited different convective characteristics. The convection in the 11 May and 23 May cases formed in smoke laden environments in the presence of convective available potential energy (CAPE) values exceeding 1000 m2 s-2 and 3000 m2 s-2 along with low-level (0-1 km) shear of 10.3 m s-1 and 5.1 m s-1, respectively. The 11 May case had linear convection while the 23 May case featured discrete supercells. The 20 May case featured elevated linear convection that formed in a more moist environment with cleaner aerosol conditions, weak CAPE (9 km) suggesting a warm rain suppression mechanism caused by a combination of strong aerosol loading, large CAPE, and weak low-level wind shear. The observed results for the 20 May and 23 May cases agree well with recent modeling studies that simulated the convection and precipitation in these cases. Furthermore, the modeling of the 11 May case is suggested since the abundant amount of smoke CCN did not greatly enhance the overall precipitation amount and could be a possible aerosol-induced precipitation suppression case.

  6. The Midlatitude Continental Convective Clouds Experiment (MC3E)

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Mark P.; Petersen, Walt A.; Bansemer, Aaron; Bharadwaj, Nitin; Carey, Larry; Cecil, D. J.; Collis, Scott M.; Del Genio, Anthony D.; Dolan, Brenda A.; Gerlach, J.; Giangrande, Scott; Heymsfield, Andrew J.; Heymsfield, Gerald; Kollias, Pavlos; Lang, T. J.; Nesbitt, Steve W.; Neumann, Andrea; Poellot, M. R.; Rutledge, Steven A.; Schwaller, Mathew R.; Tokay, Ali; Williams, C. R.; Wolff, D. B.; Xie, Shaocheng; Zipser, Edward J.

    2016-10-18

    The Midlatitude Continental Convective Clouds Experiment (MC3E), a field program jointly led by the U.S. Department of Energy’s Atmospheric Radiation Measurement program and the NASA Global Precipitation Measurement (GPM) Mission, was conducted in south-central Oklahoma during April – May 2011. MC3E science objectives were motivated by the need to improve understanding of midlatitude continental convective cloud system lifecycles, microphysics, and GPM precipitation retrieval algorithms. To achieve these objectives a multi-scale surface- and aircraft-based in situ and remote sensing observing strategy was employed. A variety of cloud and precipitation events were sampled during the MC3E, of which results from three deep convective events are highlighted. Vertical structure, air motions, precipitation drop-size distributions and ice properties were retrieved from multi-wavelength radar, profiler, and aircraft observations for an MCS on 11 May. Aircraft observations for another MCS observed on 20 May were used to test agreement between observed radar reflectivities and those calculated with forward-modeled reflectivity and microwave brightness temperatures using in situ particle size distributions and ice water content. Multi-platform observations of a supercell that occurred on 23 May allowed for an integrated analysis of kinematic and microphysical interactions. A core updraft of 25 ms-1 supported growth of hail and large rain drops. Data collected during the MC3E campaign is being used in a number of current and ongoing research projects and is available through the DOE ARM and NASA data archives.

  7. Global anthropogenic aerosol effects on convective clouds in ECHAM5-HAM

    Directory of Open Access Journals (Sweden)

    U. Lohmann

    2008-04-01

    Full Text Available Aerosols affect the climate system by changing cloud characteristics in many ways. They act as cloud condensation and ice nuclei and may have an influence on the hydrological cycle. Here we investigate aerosol effects on convective clouds by extending the double-moment cloud microphysics scheme developed for stratiform clouds, which is coupled to the HAM double-moment aerosol scheme, to convective clouds in the ECHAM5 general circulation model. This enables us to investigate whether more, and smaller cloud droplets suppress the warm rain formation in the lower parts of convective clouds and thus release more latent heat upon freezing, which would then result in more vigorous convection and more precipitation. In ECHAM5, including aerosol effects in large-scale and convective clouds (simulation ECHAM5-conv reduces the sensitivity of the liquid water path increase with increasing aerosol optical depth in better agreement with observations and large-eddy simulation studies. In simulation ECHAM5-conv with increases in greenhouse gas and aerosol emissions since pre-industrial times, the geographical distribution of the changes in precipitation better matches the observed increase in precipitation than neglecting microphysics in convective clouds. In this simulation the convective precipitation increases the most suggesting that the convection has indeed become more vigorous.

  8. Overview of the Deep Convective Clouds and Chemistry Experiment

    Science.gov (United States)

    Barth, M. C.; Brune, W. H.; Cantrell, C. A.; Rutledge, S. A.; Crawford, J. H.; Flocke, F. M.; Huntrieser, H.

    2012-12-01

    The Deep Convective Clouds and Chemistry (DC3) project conducted a 7-week field campaign during May and June 2012 to study thunderstorm dynamical, physical, and electrical characteristics, as well as their effects on the atmosphere's composition, especially ozone and particles in the climate-sensitive upper troposphere near the thunderstorm tops. The NSF/NCAR Gulfstream V (GV) and the NASA DC-8 aircraft flew 17 coordinated flights to sample low-level inflow and upper troposphere outflow air near thunderstorms and to sample convective outflow air as it chemically aged during the next 24 hours. The DLR Falcon aircraft observed the fresh storm outflow and also obtained measurements of aged outflow. In total, 19 cases of active thunderstorms and over 6 cases of photochemical aging were flown. The DC3 aircraft, based in Salina, Kansas, were equipped with instruments to measure a variety of gases, aerosols, and cloud particle characteristics in situ as well as the NASA DC-8 measuring the ozone and aerosol distribution by lidar. The aircraft targeted storms predicted to occur within range of coverage by ground-based radar pairs, lightning mapping arrays (LMAs), and frequent launches of balloon-borne instruments that could measure the storm's physical, kinematic, and lightning characteristics. This coverage occurred in three regions: 1) northeastern Colorado, 2) central Oklahoma to western Texas, and 3) northern Alabama. DC3 demonstrated that it is possible to sample with two aircraft the inflow and outflow of storms, which were simultaneously sampled by the ground radars, LMAs, and soundings. The DC3 data set is extensive and rich. This presentation will summarize the overall statistics of the DC3 measurements giving a general idea of storm characteristics, transport of trace gases, and photochemical aging of species. Examples will be given of specific thunderstorm cases, including a Colorado case where a biomass-burning plume was ingested by a storm, and of sampling a

  9. A Stochastic Framework for Modeling the Population Dynamics of Convective Clouds

    Science.gov (United States)

    Hagos, Samson; Feng, Zhe; Plant, Robert S.; Houze, Robert A.; Xiao, Heng

    2018-02-01

    A stochastic prognostic framework for modeling the population dynamics of convective clouds and representing them in climate models is proposed. The framework follows the nonequilibrium statistical mechanical approach to constructing a master equation for representing the evolution of the number of convective cells of a specific size and their associated cloud-base mass flux, given a large-scale forcing. In this framework, referred to as STOchastic framework for Modeling Population dynamics of convective clouds (STOMP), the evolution of convective cell size is predicted from three key characteristics of convective cells: (i) the probability of growth, (ii) the probability of decay, and (iii) the cloud-base mass flux. STOMP models are constructed and evaluated against CPOL radar observations at Darwin and convection permitting model (CPM) simulations. Multiple models are constructed under various assumptions regarding these three key parameters and the realisms of these models are evaluated. It is shown that in a model where convective plumes prefer to aggregate spatially and the cloud-base mass flux is a nonlinear function of convective cell area, the mass flux manifests a recharge-discharge behavior under steady forcing. Such a model also produces observed behavior of convective cell populations and CPM simulated cloud-base mass flux variability under diurnally varying forcing. In addition to its use in developing understanding of convection processes and the controls on convective cell size distributions, this modeling framework is also designed to serve as a nonequilibrium closure formulations for spectral mass flux parameterizations.

  10. Mesoscale Convective Complexes (MCCs) over the Indonesian Maritime Continent during the ENSO events

    Science.gov (United States)

    Trismidianto; Satyawardhana, H.

    2018-05-01

    This study analyzed the mesoscale convective complexes (MCCs) over the Indonesian Maritime Continent (IMC) during the El Niño/Southern Oscillation (ENSO) events for the the15-year period from 2001 to 2015. The MCCs identified by infrared satellite imagery that obtained from the Himawari generation satellite data. This study has reported that the frequencies of the MCC occurrences at the El Niño and La Niña were higher than that of neutral conditions during DJF. Peak of MCC occurrences during DJF at La Niña and neutral condition is in February, while El Niño is in January. ENSO strongly affects the occurrence of MCC during the DJF season. The existences of the MCC were also accompanied by increased rainfall intensity at the locations of the MCC occurrences for all ENSO events. During JJA seasons, the MCC occurrences are always found during neutral conditions, El Niño and La Niña in Indian Ocean. MCC occurring during the JJA season on El Niño and neutral conditions averaged much longer than during the DJF season. In contrast, MCCs occurring in La Niña conditions during the JJA season are more rapidly extinct than during the DJF. It indicates that the influence of MCC during La Niña during the DJF season is stronger than during the JJA season.

  11. Agglomeration of dust in convective clouds initialized by nuclear bursts

    Science.gov (United States)

    Bacon, D. P.; Sarma, R. A.

    Convective clouds initialized by nuclear bursts are modeled using a two-dimensional axisymmetric cloud model. Dust transport through the atmosphere is studied using five different sizes ranging from 1 to 10,000 μm in diameter. Dust is transported in the model domain by advection and sedimentation. Water is allowed to condense onto dust particles in regions of supersaturation in the cloud. The agglomeration of dust particles resulting from the collision of different size dust particles is modeled. The evolution of the dust mass spectrum due to agglomeration is modeled using a numerical scheme which is mass conserving and has low implicit diffusion. Agglomeration moves mass from the small particles with very small fall velocity to the larger sizes which fall to the ground more readily. Results indicate that the dust fallout can be increased significantly due to this process. In preliminary runs using stable and unstable environmental soundings, at 30 min after detonation the total dust in the domain was 11 and 30%, respectively, less than a control case without agglomeration.

  12. Software INCAS (Convective Clouds Indicator to Seeding Activities) to convective clouds class forecast in Mendoza (Argentina).

    Science.gov (United States)

    Pérez, R. C.

    2009-09-01

    With the objective of to get to forecast and operative determinations tool to seeding of hailstorm in the damage mitigations job that produces its precipitation in Mendoza (Argentina), we developed to software based in on surface and 500 mb. level atmospherics variable. We had used on surface dates because in this level exist to big amount of information, practically it is possible to get its measures continuously; in addition it is the level that data of damages are registered that the hail precipitation produces. The decision to use the level of 500 mb, it must to that it is the height in which the upset one of the air circulation takes place from the Pacific to Mendoza, who produces important changes and instability in the atmosphere of Mendoza, these data were obtained from the radiosonde of Santo Domingo in Santiago (Chile) and El Plumerillo (Mendoza). In the program is integrated the different indices and models obtained in ours works from investigation on the subject of last the five years. Since the October of 2004 to April of 2009 the values have been taken from the variables mentioned every day, hourly during the fight campaigns antihail (October-April). The results have integrated in the program INCAS, whom it is due to enter the surface variables: Temperature in °C, the dew point in °C, the atmospheric pressure in mb., the index of ultraviolet solar radiation, the direction and wind speed; whereas the variables of the level of 500 are due to introduce mb: height of the level of 500 mb in meters, temperature of the level in °C, the direction and wind speed to that height. From the process of these variables the type of convective process is obtained like exit of the program , that is more probable that it appears in Mendoza for these atmospheric conditions; the thresholds that trigger to the stormy processes and their possible severity. This year software was validated in his first version, obtaining itself very good results.

  13. Evaluation and Improvement of Cloud and Convective Parameterizations from Analyses of ARM Observations and Models

    Energy Technology Data Exchange (ETDEWEB)

    Del Genio, Anthony D. [NASA Goddard Inst. for Space Studies (GISS), New York, NY (United States)

    2016-03-11

    Over this period the PI and his performed a broad range of data analysis, model evaluation, and model improvement studies using ARM data. These included cloud regimes in the TWP and their evolution over the MJO; M-PACE IOP SCM-CRM intercomparisons; simulations of convective updraft strength and depth during TWP-ICE; evaluation of convective entrainment parameterizations using TWP-ICE simulations; evaluation of GISS GCM cloud behavior vs. long-term SGP cloud statistics; classification of aerosol semi-direct effects on cloud cover; depolarization lidar constraints on cloud phase; preferred states of the winter Arctic atmosphere, surface, and sub-surface; sensitivity of convection to tropospheric humidity; constraints on the parameterization of mesoscale organization from TWP-ICE WRF simulations; updraft and downdraft properties in TWP-ICE simulated convection; insights from long-term ARM records at Manus and Nauru.

  14. Microphysical effects determine macrophysical response for aerosol impacts on deep convective clouds.

    Science.gov (United States)

    Fan, Jiwen; Leung, L Ruby; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

    2013-11-26

    Deep convective clouds (DCCs) play a crucial role in the general circulation, energy, and hydrological cycle of our climate system. Aerosol particles can influence DCCs by altering cloud properties, precipitation regimes, and radiation balance. Previous studies reported both invigoration and suppression of DCCs by aerosols, but few were concerned with the whole life cycle of DCC. By conducting multiple monthlong cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macrophysical and microphysical properties of summer convective clouds and precipitation in the tropics and midlatitudes, this study provides a comprehensive view of how aerosols affect cloud cover, cloud top height, and radiative forcing. We found that although the widely accepted theory of DCC invigoration due to aerosol's thermodynamic effect (additional latent heat release from freezing of greater amount of cloud water) may work during the growing stage, it is microphysical effect influenced by aerosols that drives the dramatic increase in cloud cover, cloud top height, and cloud thickness at the mature and dissipation stages by inducing larger amounts of smaller but longer-lasting ice particles in the stratiform/anvils of DCCs, even when thermodynamic invigoration of convection is absent. The thermodynamic invigoration effect contributes up to ~27% of total increase in cloud cover. The overall aerosol indirect effect is an atmospheric radiative warming (3-5 W m(-2)) and a surface cooling (-5 to -8 W m(-2)). The modeling findings are confirmed by the analyses of ample measurements made at three sites of distinctly different environments.

  15. Snow precipitation on Mars driven by cloud-induced night-time convection

    Science.gov (United States)

    Spiga, Aymeric; Hinson, David P.; Madeleine, Jean-Baptiste; Navarro, Thomas; Millour, Ehouarn; Forget, François; Montmessin, Franck

    2017-09-01

    Although it contains less water vapour than Earth's atmosphere, the Martian atmosphere hosts clouds. These clouds, composed of water-ice particles, influence the global transport of water vapour and the seasonal variations of ice deposits. However, the influence of water-ice clouds on local weather is unclear: it is thought that Martian clouds are devoid of moist convective motions, and snow precipitation occurs only by the slow sedimentation of individual particles. Here we present numerical simulations of the meteorology in Martian cloudy regions that demonstrate that localized convective snowstorms can occur on Mars. We show that such snowstorms--or ice microbursts--can explain deep night-time mixing layers detected from orbit and precipitation signatures detected below water-ice clouds by the Phoenix lander. In our simulations, convective snowstorms occur only during the Martian night, and result from atmospheric instability due to radiative cooling of water-ice cloud particles. This triggers strong convective plumes within and below clouds, with fast snow precipitation resulting from the vigorous descending currents. Night-time convection in Martian water-ice clouds and the associated snow precipitation lead to transport of water both above and below the mixing layers, and thus would affect Mars' water cycle past and present, especially under the high-obliquity conditions associated with a more intense water cycle.

  16. Estimation of convective entrainment properties from a cloud-resolving model simulation during TWP-ICE

    Science.gov (United States)

    Zhang, Guang J.; Wu, Xiaoqing; Zeng, Xiping; Mitovski, Toni

    2016-10-01

    The fractional entrainment rate in convective clouds is an important parameter in current convective parameterization schemes of climate models. In this paper, it is estimated using a 1-km-resolution cloud-resolving model (CRM) simulation of convective clouds from TWP-ICE (the Tropical Warm Pool-International Cloud Experiment). The clouds are divided into different types, characterized by cloud-top heights. The entrainment rates and moist static energy that is entrained or detrained are determined by analyzing the budget of moist static energy for each cloud type. Results show that the entrained air is a mixture of approximately equal amount of cloud air and environmental air, and the detrained air is a mixture of ~80 % of cloud air and 20 % of the air with saturation moist static energy at the environmental temperature. After taking into account the difference in moist static energy between the entrained air and the mean environment, the estimated fractional entrainment rate is much larger than those used in current convective parameterization schemes. High-resolution (100 m) large-eddy simulation of TWP-ICE convection was also analyzed to support the CRM results. It is shown that the characteristics of entrainment rates estimated using both the high-resolution data and CRM-resolution coarse-grained data are similar. For each cloud category, the entrainment rate is high near cloud base and top, but low in the middle of clouds. The entrainment rates are best fitted to the inverse of in-cloud vertical velocity by a second order polynomial.

  17. Vertical microphysical profiles of convective clouds as a tool for obtaining aerosol cloud-mediated climate forcings

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfeld, Daniel [Hebrew Univ. of Jerusalem (Israel)

    2015-12-23

    Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Developing and validating this methodology was possible thanks to the ASR/ARM measurements of CCN and vertical updraft profiles. Validation against ground-based CCN instruments at the ARM sites in Oklahoma, Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25º restricts the satellite coverage to ~25% of the world area in a single day. This methodology will likely allow overcoming the challenge of quantifying the aerosol indirect effect and facilitate a substantial reduction of the uncertainty in anthropogenic climate forcing.

  18. Ozone mixing ratios inside tropical deep convective clouds from OMI satellite measurements

    Directory of Open Access Journals (Sweden)

    J. R. Ziemke

    2009-01-01

    Full Text Available We have developed a new technique for estimating ozone mixing ratio inside deep convective clouds. The technique uses the concept of an optical centroid cloud pressure that is indicative of the photon path inside clouds. Radiative transfer calculations based on realistic cloud vertical structure as provided by CloudSat radar data show that because deep convective clouds are optically thin near the top, photons can penetrate significantly inside the cloud. This photon penetration coupled with in-cloud scattering produces optical centroid pressures that are hundreds of hPa inside the cloud. We combine measured column ozone and the optical centroid cloud pressure derived using the effects of rotational-Raman scattering to estimate O3 mixing ratio in the upper regions of deep convective clouds. The data are obtained from the Ozone Monitoring Instrument (OMI onboard NASA's Aura satellite. Our results show that low O3 concentrations in these clouds are a common occurrence throughout much of the tropical Pacific. Ozonesonde measurements in the tropics following convective activity also show very low concentrations of O3 in the upper troposphere. These low amounts are attributed to vertical injection of ozone poor oceanic boundary layer air during convection into the upper troposphere followed by convective outflow. Over South America and Africa, O3 mixing ratios inside deep convective clouds often exceed 50 ppbv which are comparable to mean background (cloud-free amounts and are consistent with higher concentrations of injected boundary layer/lower tropospheric O3 relative to the remote Pacific. The Atlantic region in general also consists of higher amounts of O3 precursors due to both biomass burning and lightning. Assuming that O3 is well mixed (i.e., constant mixing ratio with height up to the tropopause, we can estimate the stratospheric column O3 over

  19. Background Noises Versus Intraseasonal Variation Signals: Small vs. Large Convective Cloud Objects From CERES Aqua Observations

    Science.gov (United States)

    Xu, Kuan-Man

    2015-01-01

    During inactive phases of Madden-Julian Oscillation (MJO), there are plenty of deep but small convective systems and far fewer deep and large ones. During active phases of MJO, a manifestation of an increase in the occurrence of large and deep cloud clusters results from an amplification of large-scale motions by stronger convective heating. This study is designed to quantitatively examine the roles of small and large cloud clusters during the MJO life cycle. We analyze the cloud object data from Aqua CERES (Clouds and the Earth's Radiant Energy System) observations between July 2006 and June 2010 for tropical deep convective (DC) and cirrostratus (CS) cloud object types according to the real-time multivariate MJO index, which assigns the tropics to one of the eight MJO phases each day. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The criteria for defining these cloud types are overcast footprints and cloud top pressures less than 400 hPa, but DC has higher cloud optical depths (=10) than those of CS (background noises resulting from various types of the tropical waves with different wavenumbers and propagation speeds/directions.

  20. Simulating deep convection with a shallow convection scheme

    Directory of Open Access Journals (Sweden)

    C. Hohenegger

    2011-10-01

    Full Text Available Convective processes profoundly affect the global water and energy balance of our planet but remain a challenge for global climate modeling. Here we develop and investigate the suitability of a unified convection scheme, capable of handling both shallow and deep convection, to simulate cases of tropical oceanic convection, mid-latitude continental convection, and maritime shallow convection. To that aim, we employ large-eddy simulations (LES as a benchmark to test and refine a unified convection scheme implemented in the Single-column Community Atmosphere Model (SCAM. Our approach is motivated by previous cloud-resolving modeling studies, which have documented the gradual transition between shallow and deep convection and its possible importance for the simulated precipitation diurnal cycle.

    Analysis of the LES reveals that differences between shallow and deep convection, regarding cloud-base properties as well as entrainment/detrainment rates, can be related to the evaporation of precipitation. Parameterizing such effects and accordingly modifying the University of Washington shallow convection scheme, it is found that the new unified scheme can represent both shallow and deep convection as well as tropical and mid-latitude continental convection. Compared to the default SCAM version, the new scheme especially improves relative humidity, cloud cover and mass flux profiles. The new unified scheme also removes the well-known too early onset and peak of convective precipitation over mid-latitude continental areas.

  1. Assessment of MODIS RSB Detector Uniformity Using Deep Convective Clouds

    Science.gov (United States)

    Chang, Tiejun; Xiong, Xiaoxiong (Jack); Angal, Amit; Mu, Qiaozhen

    2016-01-01

    For satellite sensor, the striping observed in images is typically associated with the relative multiple detector gain difference derived from the calibration. A method using deep convective cloud (DCC) measurements to assess the difference among detectors after calibration is proposed and demonstrated for select reflective solar bands (RSBs) of the Moderate Resolution Imaging Spectroradiometer (MODIS). Each detector of MODIS RSB is calibrated independently using a solar diffuser (SD). Although the SD is expected to accurately characterize detector response, the uncertainties associated with the SD degradation and characterization result in inadequacies in the estimation of each detector's gain. This work takes advantage of the DCC technique to assess detector uniformity and scan mirror side difference for RSB. The detector differences for Terra MODIS Collection 6 are less than 1% for bands 1, 3-5, and 18 and up to 2% for bands 6, 19, and 26. The largest difference is up to 4% for band 7. Most Aqua bands have detector differences less than 0.5% except bands 19 and 26 with up to 1.5%. Normally, large differences occur for edge detectors. The long-term trending shows seasonal oscillations in detector differences for some bands, which are correlated with the instrument temperature. The detector uniformities were evaluated for both unaggregated and aggregated detectors for MODIS band 1 and bands 3-7, and their consistencies are verified. The assessment results were validated by applying a direct correction to reflectance images. These assessments can lead to improvements to the calibration algorithm and therefore a reduction in striping observed in the calibrated imagery.

  2. The Invigoration of Deep Convective Clouds Over the Atlantic: Aerosol Effect, Meteorology or Retrieval Artifact?

    Science.gov (United States)

    Koren, Ilan; Feingold, Graham; Remer, Lorraine A.

    2010-01-01

    Associations between cloud properties and aerosol loading are frequently observed in products derived from satellite measurements. These observed trends between clouds and aerosol optical depth suggest aerosol modification of cloud dynamics, yet there are uncertainties involved in satellite retrievals that have the potential to lead to incorrect conclusions. Two of the most challenging problems are addressed here: the potential for retrieved aerosol optical depth to be cloud-contaminated, and as a result, artificially correlated with cloud parameters; and the potential for correlations between aerosol and cloud parameters to be erroneously considered to be causal. Here these issues are tackled directly by studying the effects of the aerosol on convective clouds in the tropical Atlantic Ocean using satellite remote sensing, a chemical transport model, and a reanalysis of meteorological fields. Results show that there is a robust positive correlation between cloud fraction or cloud top height and the aerosol optical depth, regardless of whether a stringent filtering of aerosol measurements in the vicinity of clouds is applied, or not. These same positive correlations emerge when replacing the observed aerosol field with that derived from a chemical transport model. Model-reanalysis data is used to address the causality question by providing meteorological context for the satellite observations. A correlation exercise between the full suite of meteorological fields derived from model reanalysis and satellite-derived cloud fields shows that observed cloud top height and cloud fraction correlate best with model pressure updraft velocity and relative humidity. Observed aerosol optical depth does correlate with meteorological parameters but usually different parameters from those that correlate with observed cloud fields. The result is a near-orthogonal influence of aerosol and meteorological fields on cloud top height and cloud fraction. The results strengthen the case

  3. Microphysical variability of vigorous Amazonian deep convection observed by CloudSat, and relevance for cloud-resolving model

    Science.gov (United States)

    Dodson, J. B.; Taylor, P. C.

    2017-12-01

    The number and varieties of both satellite cloud observations and cloud simulations are increasing rapidly. This create a challenge in identifying the best methods for quantifying the physical processes associated with deep convection, and then comparing convective observations with simulations. The use of satellite simulators in conjunction with model output is an increasingly popular method of comparison studies. However, the complexity of deep convective systems renders simplistic comparison metrics hazardous, possibly resulting is misleading or even contradicting conclusions. To investigate this, CloudSat observations of Amazonian deep convective cores (DCCs) and associated anvils are compared and contrasted with output from cloud resolving models in a manner that both highlights microphysical proprties of observed convection, and displays the effects of microphysical parameterizations on allowing robust comparisons. First, contoured frequency by altitude diagrams (CFAD) are calculated from the reflectivity fields of DCCs observed by CloudSat. This reveals two distinct modes of hydrometeor variability in the high level cloud region, with one dominated by snow and aggregates, and the other by large graupel and hail. Second, output from the superparameterized Community Atmospheric Model (SP-CAM) data are processed with the Quickbeam radar simulator to produce CFADs which can be compared with the observed CFADs. Two versions of SP-CAM are used, with one (version 4) having single-moment microphysics which excludes graupel/hail, and the other (version 5) a double-moment scheme with graupel. The change from version 4 to 5 improves the reflectivity CFAD, even without corresponding changes to non-hydrometeor fields such as vertical velocity. However, it does not produce a realistic double hydrometeor mode. Finally, the influences of microphysics are further tested in the System for Atmospheric Modeling (SAM), which allows for higher control over model parameters than

  4. Microphysical effects determine macrophysical response for aerosol impacts on deep convective clouds

    Science.gov (United States)

    Fan, Jiwen; Leung, L. Ruby; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

    2013-11-01

    Deep convective clouds (DCCs) play a crucial role in the general circulation, energy, and hydrological cycle of our climate system. Aerosol particles can influence DCCs by altering cloud properties, precipitation regimes, and radiation balance. Previous studies reported both invigoration and suppression of DCCs by aerosols, but few were concerned with the whole life cycle of DCC. By conducting multiple monthlong cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macrophysical and microphysical properties of summer convective clouds and precipitation in the tropics and midlatitudes, this study provides a comprehensive view of how aerosols affect cloud cover, cloud top height, and radiative forcing. We found that although the widely accepted theory of DCC invigoration due to aerosol's thermodynamic effect (additional latent heat release from freezing of greater amount of cloud water) may work during the growing stage, it is microphysical effect influenced by aerosols that drives the dramatic increase in cloud cover, cloud top height, and cloud thickness at the mature and dissipation stages by inducing larger amounts of smaller but longer-lasting ice particles in the stratiform/anvils of DCCs, even when thermodynamic invigoration of convection is absent. The thermodynamic invigoration effect contributes up to ∼27% of total increase in cloud cover. The overall aerosol indirect effect is an atmospheric radiative warming (3-5 Wṡm-2) and a surface cooling (-5 to -8 Wṡm-2). The modeling findings are confirmed by the analyses of ample measurements made at three sites of distinctly different environments.

  5. Evaluation of cloud convection and tracer transport in a three-dimensional chemical transport model

    Directory of Open Access Journals (Sweden)

    W. Feng

    2011-06-01

    Full Text Available We investigate the performance of cloud convection and tracer transport in a global off-line 3-D chemical transport model. Various model simulations are performed using different meteorological (reanalyses (ERA-40, ECMWF operational and ECMWF Interim to diagnose the updraft mass flux, convective precipitation and cloud top height.

    The diagnosed upward mass flux distribution from TOMCAT agrees quite well with the ECMWF reanalysis data (ERA-40 and ERA-Interim below 200 hPa. Inclusion of midlevel convection improves the agreement at mid-high latitudes. However, the reanalyses show strong convective transport up to 100 hPa, well into the tropical tropopause layer (TTL, which is not captured by TOMCAT. Similarly, the model captures the spatial and seasonal variation of convective cloud top height although the mean modelled value is about 2 km lower than observed.

    The ERA-Interim reanalyses have smaller archived upward convective mass fluxes than ERA-40, and smaller convective precipitation, which is in better agreement with satellite-based data. TOMCAT captures these relative differences when diagnosing convection from the large-scale fields. The model also shows differences in diagnosed convection with the version of the operational analyses used, which cautions against using results of the model from one specific time period as a general evaluation.

    We have tested the effect of resolution on the diagnosed modelled convection with simulations ranging from 5.6° × 5.6° to 1° × 1°. Overall, in the off-line model, the higher model resolution gives stronger vertical tracer transport, however, it does not make a large change to the diagnosed convective updraft mass flux (i.e., the model results using the convection scheme fail to capture the strong convection transport up to 100 hPa as seen in the archived convective mass fluxes. Similarly, the resolution of the forcing winds in the higher resolution CTM does not make a

  6. Feedback mechanisms of shallow convective clouds in a warmer climate as demonstrated by changes in buoyancy

    Science.gov (United States)

    Dagan, G.; Koren, I.; Altaratz, O.; Feingold, G.

    2018-05-01

    Cloud feedbacks could influence significantly the overall response of the climate system to global warming. Here we study the response of warm convective clouds to a uniform temperature change under constant relative humidity (RH) conditions. We show that an increase in temperature drives competing effects at the cloud scale: a reduction in the thermal buoyancy term and an increase in the humidity buoyancy term. Both effects are driven by the increased contrast in the water vapor content between the cloud and its environment, under warming with constant RH. The increase in the moisture content contrast between the cloud and its environment enhances the evaporation at the cloud margins, increases the entrainment, and acts to cool the cloud. Hence, there is a reduction in the thermal buoyancy term, despite the fact that theoretically this term should increase.

  7. Variability of cirrus clouds in a convective outflow during the Hibiscus campaign

    Science.gov (United States)

    Fierli, F.; di Donfrancesco, G.; Cairo, F.; Marécal, V.; Zampieri, M.; Orlandi, E.; Durry, G.

    2008-08-01

    Light-weight microlidar and water vapour measurements were taken on-board a stratospheric balloon during the HIBISCUS 2004 campaign, held in Bauru, Brazil (49° W, 22° S). Cirrus clouds were observed throughout the flight between 12 and 15 km height with a high mesoscale variability in optical and microphysical properties. It was found that the cirrus clouds were composed of different layers characterized by marked differences in height, thickness and optical properties. Simultaneous water vapour observations show that the different layers are characterized by different values of the saturation with respect to ice. A mesoscale simulation and a trajectory analysis clearly revealed that the clouds had formed in the outflow of a large and persistent convective region and that the observed variability of the optical properties and of the cloud structure is likely linked to the different residence times of the convectively-processed air in the upper troposphere.

  8. Comparison of convective clouds observed by spaceborne W-band radar and simulated by cloud-resolving atmospheric models

    Science.gov (United States)

    Dodson, Jason B.

    Deep convective clouds (DCCs) play an important role in regulating global climate through vertical mass flux, vertical water transport, and radiation. For general circulation models (GCMs) to simulate the global climate realistically, they must simulate DCCs realistically. GCMs have traditionally used cumulus parameterizations (CPs). Much recent research has shown that multiple persistent unrealistic behaviors in GCMs are related to limitations of CPs. Two alternatives to CPs exist: the global cloud-resolving model (GCRM), and the multiscale modeling framework (MMF). Both can directly simulate the coarser features of DCCs because of their multi-kilometer horizontal resolutions, and can simulate large-scale meteorological processes more realistically than GCMs. However, the question of realistic behavior of simulated DCCs remains. How closely do simulated DCCs resemble observed DCCs? In this study I examine the behavior of DCCs in the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) and Superparameterized Community Atmospheric Model (SP-CAM), the latter with both single-moment and double-moment microphysics. I place particular emphasis on the relationship between cloud vertical structure and convective environment. I also emphasize the transition between shallow clouds and mature DCCs. The spatial domains used are the tropical oceans and the contiguous United States (CONUS), the latter of which produces frequent vigorous convection during the summer. CloudSat is used to observe DCCs, and A-Train and reanalysis data are used to represent the large-scale environment in which the clouds form. The CloudSat cloud mask and radar reflectivity profiles for CONUS cumuliform clouds (defined as clouds with a base within the planetary boundary layer) during boreal summer are first averaged and compared. Both NICAM and SP-CAM greatly underestimate the vertical growth of cumuliform clouds. Then they are sorted by three large-scale environmental variables: total preciptable

  9. EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

    Science.gov (United States)

    Bony, Sandrine; Stevens, Bjorn; Ament, Felix; Bigorre, Sebastien; Chazette, Patrick; Crewell, Susanne; Delanoë, Julien; Emanuel, Kerry; Farrell, David; Flamant, Cyrille; Gross, Silke; Hirsch, Lutz; Karstensen, Johannes; Mayer, Bernhard; Nuijens, Louise; Ruppert, James H.; Sandu, Irina; Siebesma, Pier; Speich, Sabrina; Szczap, Frédéric; Totems, Julien; Vogel, Raphaela; Wendisch, Manfred; Wirth, Martin

    2017-11-01

    Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air-sea interactions and convective organization.

  10. EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

    Science.gov (United States)

    Bony, Sandrine; Stevens, Bjorn; Ament, Felix; Bigorre, Sebastien; Chazette, Patrick; Crewell, Susanne; Delanoë, Julien; Emanuel, Kerry; Farrell, David; Flamant, Cyrille; Gross, Silke; Hirsch, Lutz; Karstensen, Johannes; Mayer, Bernhard; Nuijens, Louise; Ruppert, James H.; Sandu, Irina; Siebesma, Pier; Speich, Sabrina; Szczap, Frédéric; Totems, Julien; Vogel, Raphaela; Wendisch, Manfred; Wirth, Martin

    Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of tradecumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of tradecumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air-sea interactions and convective organization.

  11. How do changes in warm-phase microphysics affect deep convective clouds?

    Science.gov (United States)

    Chen, Qian; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H.; Dagan, Guy; Pinto, Lital

    2017-08-01

    Understanding aerosol effects on deep convective clouds and the derived effects on the radiation budget and rain patterns can largely contribute to estimations of climate uncertainties. The challenge is difficult in part because key microphysical processes in the mixed and cold phases are still not well understood. For deep convective clouds with a warm base, understanding aerosol effects on the warm processes is extremely important as they set the initial and boundary conditions for the cold processes. Therefore, the focus of this study is the warm phase, which can be better resolved. The main question is: How do aerosol-derived changes in the warm phase affect the properties of deep convective cloud systems? To explore this question, we used a weather research and forecasting (WRF) model with spectral bin microphysics to simulate a deep convective cloud system over the Marshall Islands during the Kwajalein Experiment (KWAJEX). The model results were validated against observations, showing similarities in the vertical profile of radar reflectivity and the surface rain rate. Simulations with larger aerosol loading resulted in a larger total cloud mass, a larger cloud fraction in the upper levels, and a larger frequency of strong updrafts and rain rates. Enlarged mass both below and above the zero temperature level (ZTL) contributed to the increase in cloud total mass (water and ice) in the polluted runs. Increased condensation efficiency of cloud droplets governed the gain in mass below the ZTL, while both enhanced condensational and depositional growth led to increased mass above it. The enhanced mass loading above the ZTL acted to reduce the cloud buoyancy, while the thermal buoyancy (driven by the enhanced latent heat release) increased in the polluted runs. The overall effect showed an increased upward transport (across the ZTL) of liquid water driven by both larger updrafts and larger droplet mobility. These aerosol effects were reflected in the larger ratio

  12. How do changes in warm-phase microphysics affect deep convective clouds?

    Directory of Open Access Journals (Sweden)

    Q. Chen

    2017-08-01

    Full Text Available Understanding aerosol effects on deep convective clouds and the derived effects on the radiation budget and rain patterns can largely contribute to estimations of climate uncertainties. The challenge is difficult in part because key microphysical processes in the mixed and cold phases are still not well understood. For deep convective clouds with a warm base, understanding aerosol effects on the warm processes is extremely important as they set the initial and boundary conditions for the cold processes. Therefore, the focus of this study is the warm phase, which can be better resolved. The main question is: How do aerosol-derived changes in the warm phase affect the properties of deep convective cloud systems? To explore this question, we used a weather research and forecasting (WRF model with spectral bin microphysics to simulate a deep convective cloud system over the Marshall Islands during the Kwajalein Experiment (KWAJEX. The model results were validated against observations, showing similarities in the vertical profile of radar reflectivity and the surface rain rate. Simulations with larger aerosol loading resulted in a larger total cloud mass, a larger cloud fraction in the upper levels, and a larger frequency of strong updrafts and rain rates. Enlarged mass both below and above the zero temperature level (ZTL contributed to the increase in cloud total mass (water and ice in the polluted runs. Increased condensation efficiency of cloud droplets governed the gain in mass below the ZTL, while both enhanced condensational and depositional growth led to increased mass above it. The enhanced mass loading above the ZTL acted to reduce the cloud buoyancy, while the thermal buoyancy (driven by the enhanced latent heat release increased in the polluted runs. The overall effect showed an increased upward transport (across the ZTL of liquid water driven by both larger updrafts and larger droplet mobility. These aerosol effects were reflected in the

  13. Classification of Clouds and Deep Convection from GEOS-5 Using Satellite Observations

    Science.gov (United States)

    Putman, William; Suarez, Max

    2010-01-01

    With the increased resolution of global atmospheric models and the push toward global cloud resolving models, the resemblance of model output to satellite observations has become strikingly similar. As we progress with our adaptation of the Goddard Earth Observing System Model, Version 5 (GEOS-5) as a high resolution cloud system resolving model, evaluation of cloud properties and deep convection require in-depth analysis beyond a visual comparison. Outgoing long-wave radiation (OLR) provides a sufficient comparison with infrared (IR) satellite imagery to isolate areas of deep convection. We have adopted a binning technique to generate a series of histograms for OLR which classify the presence and fraction of clear sky versus deep convection in the tropics that can be compared with a similar analyses of IR imagery from composite Geostationary Operational Environmental Satellite (GOES) observations. We will present initial results that have been used to evaluate the amount of deep convective parameterization required within the model as we move toward cloud system resolving resolutions of 10- to 1-km globally.

  14. Changes in Stratiform Clouds of Mesoscale Convective Complex Introduced by Dust Aerosols

    Science.gov (United States)

    Lin, B.; Min, Q.-L.; Li, R.

    2010-01-01

    Aerosols influence the earth s climate through direct, indirect, and semi-direct effects. There are large uncertainties in quantifying these effects due to limited measurements and observations of aerosol-cloud-precipitation interactions. As a major terrestrial source of atmospheric aerosols, dusts may serve as a significant climate forcing for the changing climate because of its effect on solar and thermal radiation as well as on clouds and precipitation processes. Latest satellites measurements enable us to determine dust aerosol loadings and cloud distributions and can potentially be used to reduce the uncertainties in the estimations of aerosol effects on climate. This study uses sensors on various satellites to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective complex (MCC). A trans-Atlantic dust outbreak of Saharan origin occurring in early March 2004 is considered. For the observed MCCs under a given convective strength, small hydrometeors were found more prevalent in the dusty stratiform regions than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust regions, particularly at altitudes where heterogeneous nucleation of mineral dust prevails, further supports the observed changes of clouds and precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the size spectrum of precipitation-sized hydrometeors from heavy precipitation to light precipitation and ultimately to suppress precipitation and increase the lifecycle of cloud systems, especially over stratiform areas.

  15. A Physically Based Algorithm for Non-Blackbody Correction of Cloud-Top Temperature and Application to Convection Study

    Science.gov (United States)

    Wang, Chunpeng; Lou, Zhengzhao Johnny; Chen, Xiuhong; Zeng, Xiping; Tao, Wei-Kuo; Huang, Xianglei

    2014-01-01

    Cloud-top temperature (CTT) is an important parameter for convective clouds and is usually different from the 11-micrometers brightness temperature due to non-blackbody effects. This paper presents an algorithm for estimating convective CTT by using simultaneous passive [Moderate Resolution Imaging Spectroradiometer (MODIS)] and active [CloudSat 1 Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)] measurements of clouds to correct for the non-blackbody effect. To do this, a weighting function of the MODIS 11-micrometers band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat and CALIPSO retrievals and temperature and humidity profiles based on ECMWF analyses into a radiation transfer model.Among 16 837 tropical deep convective clouds observed by CloudSat in 2008, the averaged effective emission level (EEL) of the 11-mm channel is located at optical depth; approximately 0.72, with a standard deviation of 0.3. The distance between the EEL and cloud-top height determined by CloudSat is shown to be related to a parameter called cloud-top fuzziness (CTF), defined as the vertical separation between 230 and 10 dBZ of CloudSat radar reflectivity. On the basis of these findings a relationship is then developed between the CTF and the difference between MODIS 11-micrometers brightness temperature and physical CTT, the latter being the non-blackbody correction of CTT. Correction of the non-blackbody effect of CTT is applied to analyze convective cloud-top buoyancy. With this correction, about 70% of the convective cores observed by CloudSat in the height range of 6-10 km have positive buoyancy near cloud top, meaning clouds are still growing vertically, although their final fate cannot be determined by snapshot observations.

  16. Aerosol-Induced Changes of Convective Cloud Anvils Produce Strong Climate Warming

    Science.gov (United States)

    Koren, I.; Remer, L. A.; Altaratz, O.; Martins, J. V.; Davidi, A.

    2010-01-01

    The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm(exp-2) . Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing. We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvi1 clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming) at top-of-atmosphere. Furthermore we introduce the cloud optical depth (r), cloud height (Z) forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene. Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds; increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

  17. Aerosol-induced changes of convective cloud anvils produce strong climate warming

    Directory of Open Access Journals (Sweden)

    I. Koren

    2010-05-01

    Full Text Available The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm−2. Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing.

    We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvil clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming at top-of-atmosphere.

    Furthermore we introduce the cloud optical depth (τ, cloud height (Z forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene.

    Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds, increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

  18. Simulation of trace gas redistribution by convective clouds - Liquid phase processes

    Directory of Open Access Journals (Sweden)

    Y. Yin

    2001-01-01

    Full Text Available A two-dimensional dynamic cloud model with detailed microphysics and a spectral treatment of gas scavenging was used to simulate trace gas vertical redistribution in precipitating continental and maritime clouds. A general picture of gas transport in such clouds has been developed by examining the sensitivity to a range of parameters, including cloud dynamic and microphysical structure, gas solubility, and the method of calculating gas uptake by droplets. Gases with effective Henry's law constants (H* ranging from zero to greater than 109 mol dm-3 atm-1 were simulated. The abundance of highly soluble gases in the uppermost parts (top 1 km or so of continental precipitating clouds was found to be as much as 20-50% of that of the insoluble tracer under conditions where the mixing ratio of the tracer was approximately 5% of its boundary layer value. The abundance of highly soluble gases was approximately 6 times higher in the uppermost parts of the continental cloud than in the maritime cloud, due to differences in wet removal efficiency in the two cloud types. A fully kinetic calculation of gas uptake, as opposed to assuming Henry's law equilibrium, was found to have a significant effect on gas transport, with the abundance of highly soluble gases in the uppermost parts of the cloud being a factor of 5 lower in the equilibrium simulations. The temperature dependence of the Henry's law constant was also found to be an important parameter in determining the abundance of soluble gases at cloud top, with the abundance of moderately soluble gases being as much as 70% lower when the temperature dependence of H* was included. This reduction in abundance was found to be equivalent to increasing the temperature-independent solubility by a factor of 7. The vertical transport of soluble gases could be parameterized in large-scale models by normalizing against the transport of tracers. However, our results suggest that there is no straightforward scaling

  19. Double-moment cloud microphysics scheme for the deep convection parameterization in the GFDL AM3

    Science.gov (United States)

    Belochitski, A.; Donner, L.

    2014-12-01

    A double-moment cloud microphysical scheme originally developed by Morrision and Gettelman (2008) for the stratiform clouds and later adopted for the deep convection by Song and Zhang (2011) has been implemented in to the Geophysical Fluid Dynamics Laboratory's atmospheric general circulation model AM3. The scheme treats cloud drop, cloud ice, rain, and snow number concentrations and mixing ratios as diagnostic variables and incorporates processes of autoconversion, self-collection, collection between hydrometeor species, sedimentation, ice nucleation, drop activation, homogeneous and heterogeneous freezing, and the Bergeron-Findeisen process. Such detailed representation of microphysical processes makes the scheme suitable for studying the interactions between aerosols and convection, as well as aerosols' indirect effects on clouds and their roles in climate change. The scheme is first tested in the single column version of the GFDL AM3 using forcing data obtained at the U.S. Department of Energy Atmospheric Radiation Measurment project's Southern Great Planes site. Scheme's impact on SCM simulations is discussed. As the next step, runs of the full atmospheric GCM incorporating the new parameterization are compared to the unmodified version of GFDL AM3. Global climatological fields and their variability are contrasted with those of the original version of the GCM. Impact on cloud radiative forcing and climate sensitivity is investigated.

  20. Microphysical and Radiative Characteristics of Convective Clouds during COHMEX.

    Science.gov (United States)

    Fulton, Richard; Heymsfield, Gerald M.

    1991-01-01

    The use of passive remote microwave radiance measurements above cloud tops for rainrate estimation is complicated by the complex nature of cloud microphysics. The knowledge of the microphysical structure of clouds, specifically the hydrometeor types, shapes, sizes, and their vertical distribution, is important because radiative emission and scattering effects are dependent upon the hydrometeor distribution. This paper has two purposes: first, to document the structure and evolution of two strong thunderstorms in Alabama using radar multiparameter data; and second, to relate the inferred microphysics to the resulting upwelling microwave radiance observed concurrently by high altitude aircraft. These measurements were collected during the COHMEX field program in the summer of 1986. The radar analysis includes a description of the parameters reflectivity Z, differential reflectivity ZDR, linear depolarization ratio LDR, and hail signal HS for two thunderstorm cases on 11 July 1986. The simultaneous aircraft data includes passive microwave brightness temperature (TB) measurements at four frequencies ranging from 18 to 183 GHz as well as visible and infrared data.The remote radar observations reveal the existence of large ice particles within the storms which is likely to have caused the observed low microwave brightness temperatures. By relating the evolution of the radar measureables to the microwave TB's it has been found that knowledge of the storm microphysics and its evolution is important to adequately understand the microwave TB's.

  1. Clausius-Clapeyron Scaling of Convective Available Potential Energy (CAPE) in Cloud-Resolving Simulations

    Science.gov (United States)

    Seeley, J.; Romps, D. M.

    2015-12-01

    Recent work by Singh and O'Gorman has produced a theory for convective available potential energy (CAPE) in radiative-convective equilibrium. In this model, the atmosphere deviates from a moist adiabat—and, therefore, has positive CAPE—because entrainment causes evaporative cooling in cloud updrafts, thereby steepening their lapse rate. This has led to the proposal that CAPE increases with global warming because the strength of evaporative cooling scales according to the Clausius-Clapeyron (CC) relation. However, CAPE could also change due to changes in cloud buoyancy and changes in the entrainment rate, both of which could vary with global warming. To test the relative importance of changes in CAPE due to CC scaling of evaporative cooling, changes in cloud buoyancy, and changes in the entrainment rate, we subject a cloud-resolving model to a suite of natural (and unnatural) forcings. We find that CAPE changes are primarily driven by changes in the strength of evaporative cooling; the effect of changes in the entrainment rate and cloud buoyancy are comparatively small. This builds support for CC scaling of CAPE.

  2. Resolving both entrainment-mixing and number of activated CCN in deep convective clouds

    Directory of Open Access Journals (Sweden)

    E. Freud

    2011-12-01

    Full Text Available The number concentration of activated CCN (Na is the most fundamental microphysical property of a convective cloud. It determines the rate of droplet growth with cloud depth and conversion into precipitation-sized particles and affects the radiative properties of the clouds. However, measuring Na is not always possible, even in the cores of the convective clouds, because entrainment of sub-saturated ambient air deeper into the cloud lowers the concentrations by dilution and may cause partial or total droplet evaporation, depending on whether the mixing is homogeneous or extreme inhomogeneous, respectively.

    Here we describe a methodology to derive Na based on the rate of cloud droplet effective radius (Re growth with cloud depth and with respect to the cloud mixing with the entrained ambient air. We use the slope of the tight linear relationship between the adiabatic liquid water mixing ratio and Re3 (or Rv3 to derive an upper limit for Na assuming extreme inhomogeneous mixing. Then we tune Na down to find the theoretical relative humidity that the entrained ambient air would have for each horizontal cloud penetration, in case of homogeneous mixing. This allows us to evaluate both the entrainment and mixing process in the vertical dimension in addition to getting a better estimation for Na.

    We found that the derived Na from the entire profile data is highly correlated with the independent CCN measurements from below cloud base. Moreover, it was found that mixing of sub-saturated ambient air into the cloud at scales of ~100 m and above is inclined towards the extreme inhomogeneous limit, i.e. that the time scale of droplet evaporation is significantly smaller than that for turbulent mixing. This means that ambient air that entrains

  3. Relationships Between Tropical Deep Convection, Tropospheric Mean Temperature and Cloud-Induced Radiative Fluxes on Intraseasonal Time Scales

    Science.gov (United States)

    Ramey, Holly S.; Robertson, Franklin R.

    2010-01-01

    Intraseasonal variability of deep convection represents a fundamental mode of variability in the organization of tropical convection. While most studies of intraseasonal oscillations (ISOs) have focused on the spatial propagation and dynamics of convectively coupled circulations, we examine the projection of ISOs on the tropically-averaged temperature and energy budget. The area of interest is the global oceans between 20degN/S. Our analysis then focuses on these questions: (i) How is tropospheric temperature related to tropical deep convection and the associated ice cloud fractional amount (ICF) and ice water path (IWP)? (ii) What is the source of moisture sustaining the convection and what role does deep convection play in mediating the PBL - free atmospheric temperature equilibration? (iii) What affect do convectively generated upper-tropospheric clouds have on the TOA radiation budget? Our methodology is similar to that of Spencer et al., (2007) with some modifications and some additional diagnostics of both clouds and boundary layer thermodynamics. A composite ISO time series of cloud, precipitation and radiation quantities built from nearly 40 events during a six-year period is referenced to the atmospheric temperature signal. The increase of convective precipitation cannot be sustained by evaporation within the domain, implying strong moisture transports into the tropical ocean area. While there is a decrease in net TOA radiation that develops after the peak in deep convective rainfall, there seems little evidence that an "Infrared Iris"- like mechanism is dominant. Rather, the cloud-induced OLR increase seems largely produced by weakened convection with warmer cloud tops. Tropical ISO events offer an accessible target for studying ISOs not just in terms of propagation mechanisms, but on their global signals of heat, moisture and radiative flux feedback processes.

  4. The MJO Transition from Shallow to Deep Convection in CloudSat/CALIPSO Data and GISS GCM Simulations

    Science.gov (United States)

    DelGenio, Anthony G.; Chen, Yonghua; Kim, Daehyun; Yao, Mao-Sung

    2013-01-01

    The relationship between convective penetration depth and tropospheric humidity is central to recent theories of the Madden-Julian oscillation (MJO). It has been suggested that general circulation models (GCMs) poorly simulate the MJO because they fail to gradually moisten the troposphere by shallow convection and simulate a slow transition to deep convection. CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are analyzed to document the variability of convection depth and its relation to water vapor during the MJO transition from shallow to deep convection and to constrain GCM cumulus parameterizations. Composites of cloud occurrence for 10MJO events show the following anticipatedMJO cloud structure: shallow and congestus clouds in advance of the peak, deep clouds near the peak, and upper-level anvils after the peak. Cirrus clouds are also frequent in advance of the peak. The Advanced Microwave Scanning Radiometer for EarthObserving System (EOS) (AMSR-E) columnwater vapor (CWV) increases by;5 mmduring the shallow- deep transition phase, consistent with the idea of moisture preconditioning. Echo-top height of clouds rooted in the boundary layer increases sharply with CWV, with large variability in depth when CWV is between;46 and 68 mm. International Satellite Cloud Climatology Project cloud classifications reproduce these climatological relationships but correctly identify congestus-dominated scenes only about half the time. A version of the Goddard Institute for Space Studies Model E2 (GISS-E2) GCM with strengthened entrainment and rain evaporation that produces MJO-like variability also reproduces the shallow-deep convection transition, including the large variability of cloud-top height at intermediate CWV values. The variability is due to small grid-scale relative humidity and lapse rate anomalies for similar values of CWV. 1.

  5. Numerical simulation of self-induced rainout using a dynamic convective cloud model

    International Nuclear Information System (INIS)

    Molenkamp, C.R.

    1980-03-01

    The hypothesis that self-induced rainout can occur is supported by observations in Hiroshima and Nagasaki, where deposition of weapons debris with precipitation occurred several km downwind of the burst point. This precipitation was initiated either directly by the nuclear weapons or by the ensuing fires. Simulation of the Nagasaki event with a convection cloud precipitation scavenging model, although fraught with many questionable assumptions, agrees surprisingly well with the observations and supports the hypothesis that self-induced rainout can occur

  6. Effects of cloud condensate vertical alignment on radiative transfer calculations in deep convective regions

    Science.gov (United States)

    Wang, Xiaocong

    2017-04-01

    Effects of cloud condensate vertical alignment on radiative transfer process were investigated using cloud resolving model explicit simulations, which provide a surrogate for subgrid cloud geometry. Diagnostic results showed that the decorrelation length Lcw varies in the vertical dimension, with larger Lcw occurring in convective clouds and smaller Lcw in cirrus clouds. A new parameterization of Lcw is proposed that takes into account such varying features and gives rise to improvements in simulations of cloud radiative forcing (CRF) and radiative heating, i.e., the peak of bias is respectively reduced by 8 W m- 2 for SWCF and 2 W m- 2 for LWCF in comparison with Lcw = 1 km. The role of Lcw in modulating CRFs is twofold. On the one hand, larger Lcw tends to increase the standard deviation of optical depth στ, as dense and tenuous parts of the clouds would be increasingly aligned in the vertical dimension, thereby broadening the probability distribution. On the other hand, larger στ causes a decrease in the solar albedo and thermal emissivity, as implied in their convex functions on τ. As a result, increasing (decreasing) Lcwleads to decreased (increased) CRFs, as revealed by comparisons among Lcw = 0, Lcw = 1 km andLcw = ∞. It also affects the vertical structure of radiative flux and thus influences the radiative heating. A better representation of στ in the vertical dimension yields an improved simulation of radiative heating. Although the importance of vertical alignment of cloud condensate is found to be less than that of cloud cover in regards to their impacts on CRFs, it still has enough of an effect on modulating the cloud radiative transfer process.

  7. Toward Improving the Representation of Convection and Cloud-Radiation Interaction for Global Climate Simulations

    Science.gov (United States)

    Wu, X.; Song, X.; Deng, L.; Park, S.; Liang, X.; Zhang, G. J.

    2006-05-01

    Despite the significant progress made in developing general circulation models (GCMs), major uncertainties related to the parameterization of convection, cloud and radiation processes still remain. The current GCM credibility of seasonal-interannual climate predictions or climate change projections is limited. In particular, the following long-standing biases, common to most GCMs, need to be reduced: 1) over-prediction of high-level cloud amounts although GCMs realistically simulating the global radiation budget; 2) general failure to reproduce the seasonal variation and migration of the ITCZ precipitation; 3) incomplete representation of the Madden-Julian Oscillation (MJO); and 4) false production of an excessive cold tone of sea surface temperature across the Pacific basin and a double ITCZ structure in precipitation when the atmosphere and ocean are fully coupled. The development of cloud-resolving models (CRMs) provides a unique opportunity to address issues aimed to reduce these biases. The statistical analysis of CRM simulations together with the theoretical consideration of subgrid-scale processes will enable us to develop physically-based parameterization of convection, clouds, radiation and their interactions.

  8. Deep convective cloud characterizations from both broadband imager and hyperspectral infrared sounder measurements

    Science.gov (United States)

    Ai, Yufei; Li, Jun; Shi, Wenjing; Schmit, Timothy J.; Cao, Changyong; Li, Wanbiao

    2017-02-01

    Deep convective storms have contributed to airplane accidents, making them a threat to aviation safety. The most common method to identify deep convective clouds (DCCs) is using the brightness temperature difference (BTD) between the atmospheric infrared (IR) window band and the water vapor (WV) absorption band. The effectiveness of the BTD method for DCC detection is highly related to the spectral resolution and signal-to-noise ratio (SNR) of the WV band. In order to understand the sensitivity of BTD to spectral resolution and SNR for DCC detection, a BTD to noise ratio method using the difference between the WV and IR window radiances is developed to assess the uncertainty of DCC identification for different instruments. We examined the case of AirAsia Flight QZ8501. The brightness temperatures (Tbs) over DCCs from this case are simulated for BTD sensitivity studies by a fast forward radiative transfer model with an opaque cloud assumption for both broadband imager (e.g., Multifunction Transport Satellite imager, MTSAT-2 imager) and hyperspectral IR sounder (e.g., Atmospheric Infrared Sounder) instruments; we also examined the relationship between the simulated Tb and the cloud top height. Results show that despite the coarser spatial resolution, BTDs measured by a hyperspectral IR sounder are much more sensitive to high cloud tops than broadband BTDs. As demonstrated in this study, a hyperspectral IR sounder can identify DCCs with better accuracy.

  9. Sensitivity study of cloud/radiation interaction using a second order turbulence radiative-convective model

    International Nuclear Information System (INIS)

    Kao, C.Y.J.; Smith, W.S.

    1993-01-01

    A high resolution one-dimensional version of a second order turbulence convective/radiative model, developed at the Los Alamos National Laboratory, was used to conduct a sensitivity study of a stratocumulus cloud deck, based on data taken at San Nicolas Island during the intensive field observation marine stratocumulus phase of the First International Satellite Cloud Climatology Program (ISCCP) Regional Experiment (FIRE IFO), conducted during July, 1987. Initial profiles for liquid water potential temperature, and total water mixing ratio were abstracted from the FIRE data. The dependence of the diurnal behavior in liquid water content, cloud top height, and cloud base height were examined for variations in subsidence rate, sea surface temperature, and initial inversion strength. The modelled diurnal variation in the column integrated liquid water agrees quite well with the observed data, for the case of low subsidence. The modelled diurnal behavior for the height of the cloud top and base show qualitative agreement with the FIRE data, although the overall height of the cloud layer is about 200 meters too high

  10. Soil-plant-atmosphere conditions regulating convective cloud formation above southeastern US pine plantations.

    Science.gov (United States)

    Manoli, Gabriele; Domec, Jean-Christophe; Novick, Kimberly; Oishi, Andrew Christopher; Noormets, Asko; Marani, Marco; Katul, Gabriel

    2016-06-01

    Loblolly pine trees (Pinus taeda L.) occupy more than 20% of the forested area in the southern United States, represent more than 50% of the standing pine volume in this region, and remove from the atmosphere about 500 g C m-2 per year through net ecosystem exchange. Hence, their significance as a major regional carbon sink can hardly be disputed. What is disputed is whether the proliferation of young plantations replacing old forest in the southern United States will alter key aspects of the hydrologic cycle, including convective rainfall, which is the focus of the present work. Ecosystem fluxes of sensible (Hs) and latent heat (LE) and large-scale, slowly evolving free atmospheric temperature and water vapor content are known to be first-order controls on the formation of convective clouds in the atmospheric boundary layer. These controlling processes are here described by a zero-order analytical model aimed at assessing how plantations of different ages may regulate the persistence and transition of the atmospheric system between cloudy and cloudless conditions. Using the analytical model together with field observations, the roles of ecosystem Hs and LE on convective cloud formation are explored relative to the entrainment of heat and moisture from the free atmosphere. Our results demonstrate that cloudy-cloudless regimes at the land surface are regulated by a nonlinear relation between the Bowen ratio Bo=Hs/LE and root-zone soil water content, suggesting that young/mature pines ecosystems have the ability to recirculate available water (through rainfall predisposition mechanisms). Such nonlinearity was not detected in a much older pine stand, suggesting a higher tolerance to drought but a limited control on boundary layer dynamics. These results enable the generation of hypotheses about the impacts on convective cloud formation driven by afforestation/deforestation and groundwater depletion projected to increase following increased human population in the

  11. Sensitivity of tropical convection in cloud-resolving WRF simulations to model physics and forcing procedures

    Science.gov (United States)

    Endo, S.; Lin, W.; Jackson, R. C.; Collis, S. M.; Vogelmann, A. M.; Wang, D.; Oue, M.; Kollias, P.

    2017-12-01

    Tropical convection is one of the main drivers of the climate system and recognized as a major source of uncertainty in climate models. High-resolution modeling is performed with a focus on the deep convection cases during the active monsoon period of the TWP-ICE field campaign to explore ways to improve the fidelity of convection permitting tropical simulations. Cloud resolving model (CRM) simulations are performed with WRF modified to apply flexible configurations for LES/CRM simulations. We have enhanced the capability of the forcing module to test different implementations of large-scale vertical advective forcing, including a function for optional use of large-scale thermodynamic profiles and a function for the condensate advection. The baseline 3D CRM configurations are, following Fridlind et al. (2012), driven by observationally-constrained ARM forcing and tested with diagnosed surface fluxes and fixed sea-surface temperature and prescribed aerosol size distributions. After the spin-up period, the simulations follow the observed precipitation peaks associated with the passages of precipitation systems. Preliminary analysis shows that the simulation is generally not sensitive to the treatment of the large-scale vertical advection of heat and moisture, while more noticeable changes in the peak precipitation rate are produced when thermodynamic profiles above the boundary layer were nudged to the reference profiles from the forcing dataset. The presentation will explore comparisons with observationally-based metrics associated with convective characteristics and examine the model performance with a focus on model physics, doubly-periodic vs. nested configurations, and different forcing procedures/sources. A radar simulator will be used to understand possible uncertainties in radar-based retrievals of convection properties. Fridlind, A. M., et al. (2012), A comparison of TWP-ICE observational data with cloud-resolving model results, J. Geophys. Res., 117, D05204

  12. In situ measurements of tropical cloud properties in the West African Monsoon: upper tropospheric ice clouds, Mesoscale Convective System outflow, and subvisual cirrus

    Directory of Open Access Journals (Sweden)

    W. Frey

    2011-06-01

    Full Text Available In situ measurements of ice crystal size distributions in tropical upper troposphere/lower stratosphere (UT/LS clouds were performed during the SCOUT-AMMA campaign over West Africa in August 2006. The cloud properties were measured with a Forward Scattering Spectrometer Probe (FSSP-100 and a Cloud Imaging Probe (CIP operated aboard the Russian high altitude research aircraft M-55 Geophysica with the mission base in Ouagadougou, Burkina Faso. A total of 117 ice particle size distributions were obtained from the measurements in the vicinity of Mesoscale Convective Systems (MCS. Two to four modal lognormal size distributions were fitted to the average size distributions for different potential temperature bins. The measurements showed proportionately more large ice particles compared to former measurements above maritime regions. With the help of trace gas measurements of NO, NOy, CO2, CO, and O3 and satellite images, clouds in young and aged MCS outflow were identified. These events were observed at altitudes of 11.0 km to 14.2 km corresponding to potential temperature levels of 346 K to 356 K. In a young outflow from a developing MCS ice crystal number concentrations of up to (8.3 ± 1.6 cm−3 and rimed ice particles with maximum dimensions exceeding 1.5 mm were found. A maximum ice water content of 0.05 g m−3 was observed and an effective radius of about 90 μm. In contrast the aged outflow events were more diluted and showed a maximum number concentration of 0.03 cm−3, an ice water content of 2.3 × 10−4 g m−3, an effective radius of about 18 μm, while the largest particles had a maximum dimension of 61 μm.

    Close to the tropopause subvisual cirrus were encountered four times at altitudes of 15 km to 16.4 km. The mean ice particle number concentration of these encounters was 0.01 cm−3 with maximum particle sizes of 130

  13. The Diurnal Cycle of the Boundary Layer, Convection, Clouds, and Surface Radiation in a Coastal Monsoon Environment (Darwin Australia)

    Energy Technology Data Exchange (ETDEWEB)

    May, Peter T.; Long, Charles N.; Protat, Alain

    2012-08-01

    The diurnal variation of convection and associated cloud and radiative properties remains a significant issue in global NWP and climate models. This study analyzes observed diurnal variability of convection in a coastal monsoonal environment examining the interaction of convective rain clouds, their associated cloud properties, and the impact on the surface radiation and corresponding boundary layer structure during periods where convection is suppressed or active on the large scale. The analysis uses data from the Tropical Warm Pool International Cloud Experiment (TWP-ICE) as well as routine measurements from the Australian Bureau of Meteorology and the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. Both active monsoonal and large-scale suppressed (buildup and break) conditions are examined and demonstrate that the diurnal variation of rainfall is much larger during the break periods and the spatial distribution of rainfall is very different between the monsoon and break regimes. During the active monsoon the total net radiative input to the surface is decreased by more than 3 times the amount than during the break regime - this total radiative cloud forcing is found to be dominated by the shortwave (SW) cloud effects because of the much larger optical thicknesses and persistence of long-lasting anvils and cirrus cloud decks associated with the monsoon regime. These differences in monsoon versus break surface radiative energy contribute to low-level air temperature differences in the boundary layer over the land surfaces.

  14. Simulation of cloud/radiation interaction using a second-order turbulence radiative-convective model

    International Nuclear Information System (INIS)

    Kao, C.Y.; Smith, W.S.

    1994-01-01

    Extended sheets of low-level stratus and stratocumulus clouds are a persistent feature over the eastern parts of the major ocean basins associated with the quasi-permanent subtropical high-pressure systems. These clouds exert a strong influence on climate through their high albedo, compared with the underlying surface, and their low altitude. The former leads to a reduction of the net shortwave flux entering the atmosphere, and the latter leads to an infrared loss in a way essentially the same as the cloud-free conditions. This paper is a modeling study with the current understanding of the important physical processes associated with a cloud-capped boundary layer. The numerical model is a high-resolution one-dimensional version of the second-order turbulence convective/radiative model developed at the Los Alamos National Laboratory. Future work includes sensitivity tests to ascertain the model validity as well as to systematically include all the possible ambient atmospheric and surface conditions. Detailed budget analyses are also useful in categorizing the cloud-capped boundary layers into a few classes

  15. Convective Systems Over the Japan Sea: Cloud-Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Yoshizaki, Masanori; Shie, Chung-Lin; Kato, Teryuki

    2002-01-01

    Wintertime observations of MCSs (Mesoscale Convective Systems) over the Sea of Japan - 2001 (WMO-01) were collected from January 12 to February 1, 2001. One of the major objectives is to better understand and forecast snow systems and accompanying disturbances and the associated key physical processes involved in the formation and development of these disturbances. Multiple observation platforms (e.g., upper-air soundings, Doppler radar, wind profilers, radiometers, etc.) during WMO-01 provided a first attempt at investigating the detailed characteristics of convective storms and air pattern changes associated with winter storms over the Sea of Japan region. WMO-01 also provided estimates of the apparent heat source (Q1) and apparent moisture sink (Q2). The vertical integrals of Q1 and Q2 are equal to the surface precipitation rates. The horizontal and vertical adjective components of Q1 and Q2 can be used as large-scale forcing for the Cloud Resolving Models (CRMs). The Goddard Cumulus Ensemble (GCE) model is a CRM (typically run with a 1-km grid size). The GCE model has sophisticated microphysics and allows explicit interactions between clouds, radiation, and surface processes. It will be used to understand and quantify precipitation processes associated with wintertime convective systems over the Sea of Japan (using data collected during the WMO-01). This is the first cloud-resolving model used to simulate precipitation processes in this particular region. The GCE model-simulated WMO-01 results will also be compared to other GCE model-simulated weather systems that developed during other field campaigns (i.e., South China Sea, west Pacific warm pool region, eastern Atlantic region and central USA).

  16. Satellite-observed cold-ring-shaped features atop deep convective clouds

    Czech Academy of Sciences Publication Activity Database

    Setvák, M.; Lindsey, D. T.; Novák, P.; Wang, P. K.; Radová, Michaela; Kerkmann, J.; Grasso, L.; Su, S.-H.; Rabin, R. M.; Šťástka, J.; Charvát, Z.

    2010-01-01

    Roč. 97, 1-2 (2010), s. 80-96 ISSN 0169-8095 R&D Projects: GA ČR GA205/07/0905; GA MŠk ME09033 Institutional research plan: CEZ:AV0Z30420517 Keywords : convective storm * storm top * cloud top height * cold-ring shape * cold-U shape * enhanced-V feature * overshooting top * lower stratosphere * Meteosat second generation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.597, year: 2010 http://www.sciencedirect.com/science/article/pii/S016980951000058X

  17. Observational study of the relationship between entrainment rate and relative dispersion in deep convective clouds

    Science.gov (United States)

    Guo, Xiaohao; Lu, Chunsong; Zhao, Tianliang; Liu, Yangang; Zhang, Guang Jun; Luo, Shi

    2018-01-01

    This study investigates the influence of entrainment rate (λ) on relative dispersion (ε) of cloud droplet size distributions (CDSD) in the 99 growing precipitating deep convective clouds during TOGA-COARE. The results show that entrainment suppresses ε, which is opposite to the traditional understanding that entrainment-mixing broadens CDSD. To examine how the relationship between ε and λ is affected by droplets with different sizes, CDSDs are divided into three portions with droplet radius processes is developed to illustrate the possible scenarios entailing different relationships between ε and λ. The number concentration of small droplets and the degree of evaporation of small droplets are found to be key factors that shift the sign (i.e., positive or negative) of the ε-λ relationship.

  18. Effects of Tropical Islands on the Diurnal Cycle of Convection and its Influence on the MJO Propagation over the Maritime Continent

    Science.gov (United States)

    Savarin, A.; Chen, S. S.

    2017-12-01

    The Madden-Julian Oscillation (MJO) is a dominant mode of intraseasonal variability in the tropics. Large-scale convection fueling the MJO is initiated over the tropical Indian Ocean and propagates eastward across the Maritime Continent (MC) and into the western Pacific. Observational studies have shown that near 40-50% of the MJO events cannot pass through the MC, which is known as the MC barrier effect. Previous studies have also shown a strong diurnal cycle of convection over the islands and coastal seas, with an afternoon precipitation maximum over land and high terrain, and an early morning maximum over water and mountain valley areas. As an eastward-propagating MJO convective event passes over the MC, its nature may be altered due to the complex interaction with the large Islands and topography. In turn, the passage of an MJO event modulates local conditions over the MC. The diurnal cycle of convection over the MC and its modulation by the MJO are not well understood and poorly represented in global numerical prediction models. This study aims to improve our understanding of how the diurnal cycle of convection and the presence of islands of the MC affect the eastward propagation of the MJO over the region. To this end, we use the Unified Wave Interface-Coupled Model (UWIN-CM) in its fully-coupled atmosphere-ocean configuration at a convection-permitting (4 km) resolution over the region. The control simulation is from the MJO event that occurred in November-December 2011, and has been verified against the Dynamics of the MJO (DYNAMO) field campaign observations, TRMM precipitation, and reanalysis products. To investigate the effects of the tropical islands on the MJO, we conduct two additional numerical experiments, one with preserved island shape but flattened topography, and one where islands are replaced by water. The difference in the diurnal cycle and convective organization among these experiments will provide some insights on the origin of the MC

  19. Observations of regional and local variability in the optical properties of maritime clouds

    Energy Technology Data Exchange (ETDEWEB)

    White, A.B. [Univ. of Colorado at Boulder/National Oceanic and Atmospheric Administration, Boulder, CO (United States); Fairall, C.W. [Environmental Technology Lab., Boulder, CO (United States)

    1996-04-01

    White and Fairall (1995) calculated the optical properties of the marine boundary layer (MBL) clouds observed during the Atlantic Stratocumulus Transition Experiment (ASTEX) and compared their results with the results obtained by Fairall et al. for the MBL clouds observed during the First International Satellite Climatology Program (ISSCP) Regional Experiment (FIRE). They found a factor of two difference in the optical depth versus liquid water relationship that applies to the clouds observed in each case. In the present study, we present evidence to support this difference. We also investigate the local variability exhibited in the ASTEX optical properties using measurements of the boundary layer aerosol concentration.

  20. Cloud-Resolving Modeling Intercomparison Study of a Squall Line Case from MC3E - Properties of Convective Core

    Science.gov (United States)

    Fan, J.; Han, B.; Varble, A.; Morrison, H.; North, K.; Kollias, P.; Chen, B.; Dong, X.; Giangrande, S. E.; Khain, A.; Lin, Y.; Mansell, E.; Milbrandt, J.; Stenz, R.; Thompson, G.; Wang, Y.

    2016-12-01

    The large spread in CRM model simulations of deep convection and aerosol effects on deep convective clouds (DCCs) makes it difficult to (1) further our understanding of deep convection and (2) define "benchmarks" and then limit their use in parameterization developments. A constrained model intercomparsion study on a mid-latitude mesoscale squall line is performed using the Weather Research & Forecasting (WRF) model at 1-km horizontal grid spacing with eight cloud microphysics schemes to understand specific processes that lead to the large spreads of simulated convection and precipitation. Various observational data are employed to evaluate the baseline simulations. All simulations tend to produce a wider convective area but a much narrower stratiform area. The magnitudes of virtual potential temperature drop, pressure rise, and wind speed peak associated with the passage of the gust front are significantly smaller compared with the observations, suggesting simulated cool pools are weaker. Simulations generally overestimate the vertical velocity and radar reflectivity in convective cores compared with the retrievals. The modeled updraft velocity and precipitation have a significant spread across eight schemes. The spread of updraft velocity is the combination of both low-level pressure perturbation gradient (PPG) and buoyancy. Both PPG and thermal buoyancy are small for simulations of weak convection but both are large for those of strong convection. Ice-related parameterizations contribute majorly to the spread of updraft velocity, while they are not the reason for the large spread of precipitation. The understandings gained in this study can help to focus future observations and parameterization development.

  1. Impacts of cloud overlap assumptions on radiative budgets and heating fields in convective regions

    Science.gov (United States)

    Wang, XiaoCong; Liu, YiMin; Bao, Qing

    2016-01-01

    Impacts of cloud overlap assumptions on radiative budgets and heating fields are explored with the aid of a cloud-resolving model (CRM), which provided cloud geometry as well as cloud micro and macro properties. Large-scale forcing data to drive the CRM are from TRMM Kwajalein Experiment and the Global Atmospheric Research Program's Atlantic Tropical Experiment field campaigns during which abundant convective systems were observed. The investigated overlap assumptions include those that were traditional and widely used in the past and the one that was recently addressed by Hogan and Illingworth (2000), in which the vertically projected cloud fraction is expressed by a linear combination of maximum and random overlap, with the weighting coefficient depending on the so-called decorrelation length Lcf. Results show that both shortwave and longwave cloud radiative forcings (SWCF/LWCF) are significantly underestimated under maximum (MO) and maximum-random (MRO) overlap assumptions, whereas remarkably overestimated under the random overlap (RO) assumption in comparison with that using CRM inherent cloud geometry. These biases can reach as high as 100 Wm- 2 for SWCF and 60 Wm- 2 for LWCF. By its very nature, the general overlap (GenO) assumption exhibits an encouraging performance on both SWCF and LWCF simulations, with the biases almost reduced by 3-fold compared with traditional overlap assumptions. The superiority of GenO assumption is also manifested in the simulation of shortwave and longwave radiative heating fields, which are either significantly overestimated or underestimated under traditional overlap assumptions. The study also pointed out the deficiency of constant assumption on Lcf in GenO assumption. Further examinations indicate that the CRM diagnostic Lcf varies among different cloud types and tends to be stratified in the vertical. The new parameterization that takes into account variation of Lcf in the vertical well reproduces such a relationship and

  2. The 3-D Tropical Convective Cloud Spectrum in AMIE Radar Observations and Global Climate Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, Courtney [Texas A & M Univ., College Station, TX (United States). Dept. of Atmospheric Sciences

    2015-08-31

    During the three years of this grant performance, the PI and her research group have made a number of significant contributions towards determining properties of tropical deep convective clouds and how models depict and respond to the heating associated with tropical convective systems. The PI has also been an active ARM/ASR science team member, including playing a significant role in AMIE and GoAmazon2014/5. She served on the DOE ASR radar science steering committee and was a joint chair of the Mesoscale Convective Organization group under the Cloud Life Cycle working group. This grant has funded a number of graduate students, many of them women, and the PI and her group have presented their DOE-supported work at various universities and national meetings. The PI and her group participated in the AMIE (2011-12) and GoAmazon2014/5 (2014-15) DOE field deployments that occurred in the tropical Indian Ocean and Brazilian Amazon, respectively. AMIE observational results (DePasquale et al. 2014, Feng et al. 2014, Ahmed and Schumacher 2015) focus on the variation and possible importance of Kelvin waves in various phases of the Madden-Julian Oscillation (MJO), on the synergy of the different wavelength radars deployed on Addu Atoll, and on the importance of humidity thresholds in the tropics on stratiform rain production. Much of the PIs GoAmazon2014/5 results to date relate to overviews of the observations made during the field campaign (Martin et al. 2015, 2016; Fuentes et al. 2016), but also include the introduction of the descending arm and its link to ozone transport from the mid-troposphere to the surface (Gerken et al. 2016). Vertical motion and mass flux profiles from GoAmazon (Giangrande et al. 2016) also show interesting patterns between seasons and provide targets for model simulations. Results from TWP-ICE (Schumacher et al. 2015), which took place in Darwin, Australia in 2006 show that vertical velocity retrievals from the profilers provide structure to

  3. The effect of aerosol-derived changes in the warm phase on the properties of deep convective clouds

    Science.gov (United States)

    Chen, Qian; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven; Dagan, Guy

    2017-04-01

    The aerosol impact on deep convective clouds starts in an increased number of cloud droplets in higher aerosol loading environment. This change drives many others, like enhanced condensational growth, delay in collision-coalescence and others. Since the warm processes serve as the initial and boundary conditions for the mixed and cold-phase processes in deep clouds, it is highly important to understand the aerosol effect on them. The weather research and forecasting model (WRF) with spectral bin microphysics was used to study a deep convective system over the Marshall Islands, during the Kwajalein Experiment (KWAJEX). Three simulations were conducted with aerosol concentrations of 100, 500 and 2000 cm-3, to reflect clean, semipolluted, and polluted conditions. The results of the clean run agreed well with the radar profiles and rain rate observations. The more polluted simulations resulted in larger total cloud mass, larger upper level cloud fraction and rain rates. There was an increased mass both below and above the zero temperature level. It indicates of more efficient growth processes both below and above the zero level. In addition the polluted runs showed an increased upward transport (across the zero level) of liquid water due to both stronger updrafts and larger droplet mobility. In this work we discuss the transport of cloud mass crossing the zero temperature level (in both directions) in order to gain a process level understanding of how aerosol effects on the warm processes affect the macro- and micro-properties of deep convective clouds.

  4. The implications of dust ice nuclei effect on cloud top temperature in a complex mesoscale convective system.

    Science.gov (United States)

    Li, Rui; Dong, Xue; Guo, Jingchao; Fu, Yunfei; Zhao, Chun; Wang, Yu; Min, Qilong

    2017-10-23

    Mineral dust is the most important natural source of atmospheric ice nuclei (IN) which may significantly mediate the properties of ice cloud through heterogeneous nucleation and lead to crucial impacts on hydrological and energy cycle. The potential dust IN effect on cloud top temperature (CTT) in a well-developed mesoscale convective system (MCS) was studied using both satellite observations and cloud resolving model (CRM) simulations. We combined satellite observations from passive spectrometer, active cloud radar, lidar, and wind field simulations from CRM to identify the place where ice cloud mixed with dust particles. For given ice water path, the CTT of dust-mixed cloud is warmer than that in relatively pristine cloud. The probability distribution function (PDF) of CTT for dust-mixed clouds shifted to the warmer end and showed two peaks at about -45 °C and -25 °C. The PDF for relatively pristine cloud only show one peak at -55 °C. Cloud simulations with different microphysical schemes agreed well with each other and showed better agreement with satellite observations in pristine clouds, but they showed large discrepancies in dust-mixed clouds. Some microphysical schemes failed to predict the warm peak of CTT related to heterogeneous ice formation.

  5. Role of atmospheric aerosol concentration on deep convective precipitation: Cloud-resolving model simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2007-12-01

    A two-dimensional cloud-resolving model with detailed spectral bin microphysics is used to examine the effect of aerosols on three different deep convective cloud systems that developed in different geographic locations: south Florida, Oklahoma, and the central Pacific. A pair of model simulations, one with an idealized low cloud condensation nuclei (CCN) (clean) and one with an idealized high CCN (dirty environment), is conducted for each case. In all three cases, rain reaches the ground earlier for the low-CCN case. Rain suppression is also evident in all three cases with high CCN. However, this suppression only occurs during the early stages of the simulations. During the mature stages of the simulations the effects of increasing aerosol concentration range from rain suppression in the Oklahoma case to almost no effect in the Florida case to rain enhancement in the Pacific case. The model results suggest that evaporative cooling in the lower troposphere is a key process in determining whether high CCN reduces or enhances precipitation. Stronger evaporative cooling can produce a stronger cold pool and thus stronger low-level convergence through interactions with the low-level wind shear. Consequently, precipitation processes can be more vigorous. For example, the evaporative cooling is more than two times stronger in the lower troposphere with high CCN for the Pacific case. Sensitivity tests also suggest that ice processes are crucial for suppressing precipitation in the Oklahoma case with high CCN. A comparison and review of other modeling studies are also presented.

  6. Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON–CHUVA campaign

    Directory of Open Access Journals (Sweden)

    R. C. Braga

    2017-06-01

    Full Text Available The objective of this study is to validate parameterizations that were recently developed for satellite retrievals of cloud condensation nuclei supersaturation spectra, NCCN(S, at cloud base alongside more traditional parameterizations connecting NCCN(S with cloud base updrafts and drop concentrations. This was based on the HALO aircraft measurements during the ACRIDICON–CHUVA campaign over the Amazon region, which took place in September 2014. The properties of convective clouds were measured with a cloud combination probe (CCP, a cloud and aerosol spectrometer (CAS-DPOL, and a CCN counter onboard the HALO aircraft. An intercomparison of the cloud drop size distributions (DSDs and the cloud water content (CWC derived from the different instruments generally shows good agreement within the instrumental uncertainties. To this end, the directly measured cloud drop concentrations (Nd near cloud base were compared with inferred values based on the measured cloud base updraft velocity (Wb and NCCN(S spectra. The measurements of Nd at cloud base were also compared with drop concentrations (Na derived on the basis of an adiabatic assumption and obtained from the vertical evolution of cloud drop effective radius (re above cloud base. The measurements of NCCN(S and Wb reproduced the observed Nd within the measurements uncertainties when the old (1959 Twomey's parameterization was used. The agreement between the measured and calculated Nd was only within a factor of 2 with attempts to use cloud base S, as obtained from the measured Wb, Nd, and NCCN(S. This underscores the yet unresolved challenge of aircraft measurements of S in clouds. Importantly, the vertical evolution of re with height reproduced the observation-based nearly adiabatic cloud base drop concentrations, Na. The combination of these results provides aircraft observational support for the various components of the satellite-retrieved methodology that was recently developed to

  7. Retrieving latent heating vertical structure from cloud and precipitation profiles—Part II: Deep convective and stratiform rain processes

    International Nuclear Information System (INIS)

    Li, Rui; Min, Qilong; Wu, Xiaoqing; Fu, Yunfei

    2013-01-01

    An exploratory study on physical based latent heat (LH) retrieval algorithm is conducted by parameterizing the physical linkages between observed cloud and precipitation profiles to the major processes of phase change of atmospheric water. Specifically, rain is segregated into three rain types: warm, convective, and stratiform rain, based on their dynamical and thermodynamical characteristics. As the second of series, both convective and stratiform rain LH algorithms are presented and evaluated here. For convective and stratiform rain, the major LH-related microphysical processes including condensation, deposition, evaporation, sublimation, and freezing–melting are parameterized with the aid of Cloud Resolving Model (CRM) simulations. The condensation and deposition processes are parameterized in terms of rain formation processes through the precipitation formation theory. LH associated with the freezing–melting process is relatively small and is assumed to be a fraction of total condensation and deposition LH. The evaporation and sublimation processes are parameterized for three unsaturated scenarios: rain out of the cloud body, clouds at cloud boundary and clouds and rain in downdraft region. The evaluation or self-consistency test indicates the retrievals capture the major features of LH profiles and reproduce the double peaks at right altitudes. The LH products are applicable at various stages of cloud system life cycle for high-resolution models, as well as for large-scale climate models. -- Highlights: ► An exploratory study on physics-based cold rain latent heat retrieval algorithm. ► Utilize the full information of the vertical structures of cloud and rainfall. ► Include all major LH-related microphysical processes (in ice and liquid phase). ► Directly link water mass measurements to latent heat at instantaneous pixel level. ► Applicable at various stages of cloud system life cycle

  8. Retrievals of Ice Cloud Microphysical Properties of Deep Convective Systems using Radar Measurements

    Science.gov (United States)

    Tian, J.; Dong, X.; Xi, B.; Wang, J.; Homeyer, C. R.

    2015-12-01

    This study presents innovative algorithms for retrieving ice cloud microphysical properties of Deep Convective Systems (DCSs) using Next-Generation Radar (NEXRAD) reflectivity and newly derived empirical relationships from aircraft in situ measurements in Wang et al. (2015) during the Midlatitude Continental Convective Clouds Experiment (MC3E). With composite gridded NEXRAD radar reflectivity, four-dimensional (space-time) ice cloud microphysical properties of DCSs are retrieved, which is not possible from either in situ sampling at a single altitude or from vertical pointing radar measurements. For this study, aircraft in situ measurements provide the best-estimated ice cloud microphysical properties for validating the radar retrievals. Two statistical comparisons between retrieved and aircraft in situ measured ice microphysical properties are conducted from six selected cases during MC3E. For the temporal-averaged method, the averaged ice water content (IWC) and median mass diameter (Dm) from aircraft in situ measurements are 0.50 g m-3 and 1.51 mm, while the retrievals from radar reflectivity have negative biases of 0.12 g m-3 (24%) and 0.02 mm (1.3%) with correlations of 0.71 and 0.48, respectively. For the spatial-averaged method, the IWC retrievals are closer to the aircraft results (0.51 vs. 0.47 g m-3) with a positive bias of 8.5%, whereas the Dm retrievals are larger than the aircraft results (1.65 mm vs. 1.51 mm) with a positive bias of 9.3%. The retrieved IWCs decrease from ~0.6 g m-3 at 5 km to ~0.15 g m-3 at 13 km, and Dm values decrease from ~2 mm to ~0.7 mm at the same levels. In general, the aircraft in situ measured IWC and Dm values at each level are within one standard derivation of retrieved properties. Good agreements between microphysical properties measured from aircraft and retrieved from radar reflectivity measurements indicate the reasonable accuracy of our retrievals.

  9. Polarimetric radar convective cell tracking reveals large sensitivity of cloud precipitation and electrification properties to CCN

    Science.gov (United States)

    Hu, J.; Rosenfeld, D.; Zhang, P.; Snyder, J.; Orville, R. E.; Ryzhkov, A.; Zrnic, D.; Williams, E. R.; Zhang, R.

    2017-12-01

    Here we apply the cell tracking methodology, shown in our companion poster, to quantifying factors affecting the vigor and the time-height evolution of hydrometeors and electrification properties of convective cells. Benefitting from the Dual-polarimetric NEXRAD radar network, we composite more than 5000 well-tracked cells among three radars (at Houston, Lubbock and Oklahoma City), stratified by CCN, CAPE and land/sea locations. The analyzed cell properties include Z, ZDR, Kdp, and ρhv, Dm (raindrop diameter) and Nw (raindrop concentration) by the algorithm of Bringi et al. (2003). Lightning Mapping Array (LMA) data is also included in the analysis, which provides a 3D structure of lightning occurrence and RF power. The contrasting CCN conditions over marine, land, pristine and polluted areas are identified based on the satellite retrieval technique described in Rosenfeld et al. (2016). The results show that more CCN are associated with: Increased echo top height, manifesting the invigoration effect. Enhanced reflectivities, especially above the freezing level at around 4.5 km. Raindrop sizes at the initial stage increase at the expense of their concentrations, due to the smaller cloud droplets and suppressed coalescence. Larger propensity for hail. Lightning sources increase with greater CCN concentration and is likely due to the delayed warm rain process and enhanced mixed phase process under more CCN condition, when activated CCN into cloud droplets is too high (> 1000 cm-3) the glaciation is delayed too much and leave little ice at lower levels and thus decrease lightning activity. Land pristine clouds have fewer lightning sources than polluted clouds. Marine pristine clouds seldom have lightning Increased CAPE had a similar effect to the effect of added CCN. The cloud tracking and properties are obtained by a new methodology of Multi-Cell Identification and Tracking (MCIT) algorithm (Hu et al, 2017), with details about the algorithm to be found in the author

  10. The impact of cloud inhomogeneities on the Earth radiation budget: the 14 October 1989 I.C.E. convective cloud case study

    Directory of Open Access Journals (Sweden)

    F. Parol

    1994-01-01

    Full Text Available Through their multiple interactions with radiation, clouds have an important impact on the climate. Nonetheless, the simulation of clouds in climate models is still coarse. The present evolution of modeling tends to a more realistic representation of the liquid water content; thus the problem of its subgrid scale distribution is crucial. For a convective cloud field observed during ICE 89, Landsat TM data (resolution: 30m have been analyzed in order to quantify the respective influences of both the horizontal distribution of liquid water content and cloud shape on the Earth radiation budget. The cloud field was found to be rather well-represented by a stochastic distribution of hemi-ellipsoidal clouds whose horizontal aspect ratio is close to 2 and whose vertical aspect ratio decreases as the cloud cell area increases. For that particular cloud field, neglecting the influence of the cloud shape leads to an over-estimate of the outgoing longwave flux; in the shortwave, it leads to an over-estimate of the reflected flux for high solar elevations but strongly depends on cloud cell orientations for low elevations. On the other hand, neglecting the influence of cloud size distribution leads to systematic over-estimate of their impact on the shortwave radiation whereas the effect is close to zero in the thermal range. The overall effect of the heterogeneities is estimated to be of the order of 10 W m-2 for the conditions of that Landsat picture (solar zenith angle 65°, cloud cover 70%; it might reach 40 W m-2 for an overhead sun and overcast cloud conditions.

  11. The impact of cloud inhomogeneities on the Earth radiation budget: the 14 October 1989 I.C.E. convective cloud case study

    Directory of Open Access Journals (Sweden)

    F. Parol

    Full Text Available Through their multiple interactions with radiation, clouds have an important impact on the climate. Nonetheless, the simulation of clouds in climate models is still coarse. The present evolution of modeling tends to a more realistic representation of the liquid water content; thus the problem of its subgrid scale distribution is crucial. For a convective cloud field observed during ICE 89, Landsat TM data (resolution: 30m have been analyzed in order to quantify the respective influences of both the horizontal distribution of liquid water content and cloud shape on the Earth radiation budget. The cloud field was found to be rather well-represented by a stochastic distribution of hemi-ellipsoidal clouds whose horizontal aspect ratio is close to 2 and whose vertical aspect ratio decreases as the cloud cell area increases. For that particular cloud field, neglecting the influence of the cloud shape leads to an over-estimate of the outgoing longwave flux; in the shortwave, it leads to an over-estimate of the reflected flux for high solar elevations but strongly depends on cloud cell orientations for low elevations. On the other hand, neglecting the influence of cloud size distribution leads to systematic over-estimate of their impact on the shortwave radiation whereas the effect is close to zero in the thermal range. The overall effect of the heterogeneities is estimated to be of the order of 10 W m-2 for the conditions of that Landsat picture (solar zenith angle 65°, cloud cover 70%; it might reach 40 W m-2 for an overhead sun and overcast cloud conditions.

  12. CARIBIC DOAS observations of nitrous acid and formaldehyde in a large convective cloud

    Science.gov (United States)

    Heue, K.-P.; Riede, H.; Walter, D.; Brenninkmeijer, C. A. M.; Wagner, T.; Frieß, U.; Platt, U.; Zahn, A.; Stratmann, G.; Ziereis, H.

    2014-07-01

    The chemistry in large thunderstorm clouds is influenced by local lightning-NOx production and uplift of boundary layer air. Under these circumstances trace gases like nitrous acid (HONO) or formaldehyde (HCHO) are expected to be formed or to reach the tropopause region. However, up to now only few observations of HONO at this altitude have been reported. Here we report on a case study where enhancements in HONO, HCHO and nitrogen oxides (NOx) were observed by the CARIBIC flying laboratory (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container). The event took place in a convective system over the Caribbean Sea in August 2011. Inside the cloud the light path reaches up to 100 km. Therefore the DOAS instrument on CARIBIC was very sensitive to the tracers inside the cloud. Based on the enhanced slant column densities of HONO, HCHO and NO2, average mixing ratios of 37, 468 and 210 ppt, respectively, were calculated. These data represent averages for constant mixing ratios inside the cloud. However, a large dependency on the assumed profile is found; for HONO a mixing ratio of 160 ppt is retrieved if the total amount is assumed to be situated in the uppermost 2 km of the cloud. The NO in situ instrument measured peaks up to 5 ppb NO inside the cloud; the background in the cloud was about 1.3 ppb, and hence clearly above the average outside the cloud (≈ 150 ppt). The high variability and the fact that the enhancements were observed over a pristine marine area led to the conclusion that, in all likelihood, the high NO concentrations were caused by lighting. This assumption is supported by the number of flashes that the World Wide Lightning Location Network (WWLLN) counted in this area before and during the overpass. The chemical box model CAABA is used to estimate the NO and HCHO source strengths which are necessary to explain our measurements. For NO a source strength of 10 × 109 molec cm-2 s-1 km-1 is found, which

  13. Comparing airborne and satellite retrievals of cloud optical thickness and particle effective radius using a spectral radiance ratio technique: two case studies for cirrus and deep convective clouds

    Science.gov (United States)

    Krisna, Trismono C.; Wendisch, Manfred; Ehrlich, André; Jäkel, Evelyn; Werner, Frank; Weigel, Ralf; Borrmann, Stephan; Mahnke, Christoph; Pöschl, Ulrich; Andreae, Meinrat O.; Voigt, Christiane; Machado, Luiz A. T.

    2018-04-01

    Solar radiation reflected by cirrus and deep convective clouds (DCCs) was measured by the Spectral Modular Airborne Radiation Measurement System (SMART) installed on the German High Altitude and Long Range Research Aircraft (HALO) during the Mid-Latitude Cirrus (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interaction and Dynamic of Convective Clouds System - Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modelling and to the Global Precipitation Measurement (ACRIDICON-CHUVA) campaigns. On particular flights, HALO performed measurements closely collocated with overpasses of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite. A cirrus cloud located above liquid water clouds and a DCC topped by an anvil cirrus are analyzed in this paper. Based on the nadir spectral upward radiance measured above the two clouds, the optical thickness τ and particle effective radius reff of the cirrus and DCC are retrieved using a radiance ratio technique, which considers the cloud thermodynamic phase, the vertical profile of cloud microphysical properties, the presence of multilayer clouds, and the heterogeneity of the surface albedo. For the cirrus case, the comparison of τ and reff retrieved on the basis of SMART and MODIS measurements yields a normalized mean absolute deviation of up to 1.2 % for τ and 2.1 % for reff. For the DCC case, deviations of up to 3.6 % for τ and 6.2 % for reff are obtained. The larger deviations in the DCC case are mainly attributed to the fast cloud evolution and three-dimensional (3-D) radiative effects. Measurements of spectral upward radiance at near-infrared wavelengths are employed to investigate the vertical profile of reff in the cirrus. The retrieved values of reff are compared with corresponding in situ measurements using a vertical weighting method. Compared to the MODIS observations, measurements of SMART provide more information on the

  14. Determining ice water content from 2D crystal images in convective cloud systems

    Science.gov (United States)

    Leroy, Delphine; Coutris, Pierre; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter

    2016-04-01

    Cloud microphysical in-situ instrumentation measures bulk parameters like total water content (TWC) and/or derives particle size distributions (PSD) (utilizing optical spectrometers and optical array probes (OAP)). The goal of this work is to introduce a comprehensive methodology to compute TWC from OAP measurements, based on the dataset collected during recent HAIC (High Altitude Ice Crystals)/HIWC (High Ice Water Content) field campaigns. Indeed, the HAIC/HIWC field campaigns in Darwin (2014) and Cayenne (2015) provide a unique opportunity to explore the complex relationship between cloud particle mass and size in ice crystal environments. Numerous mesoscale convective systems (MCSs) were sampled with the French Falcon 20 research aircraft at different temperature levels from -10°C up to 50°C. The aircraft instrumentation included an IKP-2 (isokinetic probe) to get reliable measurements of TWC and the optical array probes 2D-S and PIP recording images over the entire ice crystal size range. Based on the known principle relating crystal mass and size with a power law (m=α•Dβ), Fontaine et al. (2014) performed extended 3D crystal simulations and thereby demonstrated that it is possible to estimate the value of the exponent β from OAP data, by analyzing the surface-size relationship for the 2D images as a function of time. Leroy et al. (2015) proposed an extended version of this method that produces estimates of β from the analysis of both the surface-size and perimeter-size relationships. Knowing the value of β, α then is deduced from the simultaneous IKP-2 TWC measurements for the entire HAIC/HIWC dataset. The statistical analysis of α and β values for the HAIC/HIWC dataset firstly shows that α is closely linked to β and that this link changes with temperature. From these trends, a generalized parameterization for α is proposed. Finally, the comparison with the initial IKP-2 measurements demonstrates that the method is able to predict TWC values

  15. FlorNExT®, a cloud computing application to estimate growth and yield of maritime pine (Pinus pinaster Ait. stands in Northeastern Portugal

    Directory of Open Access Journals (Sweden)

    Fernando Pérez-Rodríguez

    2016-07-01

    Full Text Available Aim of the study: To introduce and describe FlorNExT®, a free cloud computing application to estimate growth and yield of maritime pine (Pinus pinaster Ait. even-aged stands in the Northeast of Portugal (NE Portugal. Area of study: NE Portugal. Material and methods: FlorNExT® implements a dynamic growth and yield modelling framework which integrates transition functions for dominant height (site index curves and basal area, as well as output functions for tree and stand volume, biomass, and carbon content. Main results: FlorNExT® is freely available from any device with an Internet connection at: http://flornext.esa.ipb.pt/. Research highlights: This application has been designed to make it possible for any stakeholder to easily estimate standing volume, biomass, and carbon content in maritime pine stands from stand data, as well as to estimate growth and yield based on four stand variables: age, density, dominant height, and basal area. FlorNExT® allows planning thinning treatments. FlorNExT® is a fundamental tool to support forest mobilization at local and regional scales in NE Portugal. Keywords: forest management; maritime pine; forest modelling; knowledge transfer tool.

  16. Vertical distribution of the particle phase in tropical deep convective clouds as derived from cloud-side reflected solar radiation measurements

    Directory of Open Access Journals (Sweden)

    E. Jäkel

    2017-07-01

    Full Text Available Vertical profiles of cloud particle phase in tropical deep convective clouds (DCCs were investigated using airborne solar spectral radiation data collected by the German High Altitude and Long Range Research Aircraft (HALO during the ACRIDICON-CHUVA campaign, which was conducted over the Brazilian rainforest in September 2014. A phase discrimination retrieval based on imaging spectroradiometer measurements of DCC side spectral reflectivity was applied to clouds formed in different aerosol conditions. From the retrieval results the height of the mixed-phase layer of the DCCs was determined. The retrieved profiles were compared with in situ measurements and satellite observations. It was found that the depth and vertical position of the mixed-phase layer can vary up to 900 m for one single cloud scene. This variability is attributed to the different stages of cloud development in a scene. Clouds of mature or decaying stage are affected by falling ice particles resulting in lower levels of fully glaciated cloud layers compared to growing clouds. Comparing polluted and moderate aerosol conditions revealed a shift of the lower boundary of the mixed-phase layer from 5.6 ± 0.2 km (269 K; moderate to 6.2 ± 0.3 km (267 K; polluted, and of the upper boundary from 6.8 ± 0.2 km (263 K; moderate to 7.4 ± 0.4 km (259 K; polluted, as would be expected from theory.

  17. VIIRS Reflective Solar Band Radiometric and Stability Evaluation Using Deep Convective Clouds

    Science.gov (United States)

    Chang, Tiejun; Xiong, Xiaoxiong; Mu, Qiaozhen

    2016-01-01

    This work takes advantage of the stable distribution of deep convective cloud (DCC) reflectance measurements to assess the calibration stability and detector difference in Visible Infrared Imaging Radiometer Suite (VIIRS) reflective bands. VIIRS Sensor Data Records (SDRs) from February 2012 to June 2015 are utilized to analyze the long-term trending, detector difference, and half angle mirror (HAM) side difference. VIIRS has two thermal emissive bands with coverage crossing 11 microns for DCC pixel identification. The comparison of the results of these two processing bands is one of the indicators of analysis reliability. The long-term stability analysis shows downward trends (up to approximately 0.4 per year) for the visible and near-infrared bands and upward trends (up to 0.5per year) for the short- and mid-wave infrared bands. The detector difference for each band is calculated as the difference relative to the average reflectance overall detectors. Except for the slightly greater than 1 difference in the two bands at 1610 nm, the detector difference is less than1 for other solar reflective bands. The detector differences show increasing trends for some short-wave bands with center wavelengths from 400 to 600 nm and remain unchanged for the bands with longer center wavelengths. The HAM side difference is insignificant and stable. Those short-wave bands from 400 to 600 nm also have relatively larger HAM side difference, up to 0.25.Comparing the striped images from SDR and the smooth images after the correction validates the analyses of detector difference and HAM side difference. These analyses are very helpful for VIIRS calibration improvement and thus enhance product quality

  18. Assessment of MODIS On-Orbit Calibration Using a Deep Convective Cloud Technique

    Science.gov (United States)

    Mu, Qiaozhen; Wu, Aisheng; Chang, Tiejun; Angal, Amit; Link, Daniel; Xiong, Xiaoxiong; Doelling, David R.; Bhatt, Rajendra

    2016-01-01

    The MODerate Resolution Imaging Spectroradiometer (MODIS) sensors onboard Terra and Aqua satellites are calibrated on-orbit with a solar diffuser (SD) for the reflective solar bands (RSB). The MODIS sensors are operating beyond their designed lifetime and hence present a major challenge to maintain the calibration accuracy. The degradation of the onboard SD is tracked by a solar diffuser stability monitor (SDSM) over a wavelength range from 0.41 to 0.94 micrometers. Therefore, any degradation of the SD beyond 0.94 micrometers cannot be captured by the SDSM. The uncharacterized degradation at wavelengths beyond this limit could adversely affect the Level 1B (L1B) product. To reduce the calibration uncertainties caused by the SD degradation, invariant Earth-scene targets are used to monitor and calibrate the MODIS L1B product. The use of deep convective clouds (DCCs) is one such method and particularly significant for the short-wave infrared (SWIR) bands in assessing their long-term calibration stability. In this study, we use the DCC technique to assess the performance of the Terra and Aqua MODIS Collection-6 L1B for RSB 1 3- 7, and 26, with spectral coverage from 0.47 to 2.13 micrometers. Results show relatively stable trends in Terra and Aqua MODIS reflectance for most bands. Careful attention needs to be paid to Aqua band 1, Terra bands 3 and 26 as their trends are larger than 1% during the study time period. We check the feasibility of using the DCC technique to assess the stability in MODIS bands 17-19. The assessment test on response versus scan angle (RVS) calibration shows substantial trend difference for Aqua band 1between different angles of incidence (AOIs). The DCC technique can be used to improve the RVS calibration in the future.

  19. Regional Maritime University Journal

    African Journals Online (AJOL)

    Maritime education and training; Maritime technology; Maritime administration; Maritime environmental and ocean management; Port and shipping administration; Maritime transport and logistics; Maritime policy and practices; Maritime safety and security; Engineering; Information Communication Technology; Oil and gas ...

  20. Improving representation of convective transport for scale-aware parameterization: 2. Analysis of cloud-resolving model simulations

    Science.gov (United States)

    Liu, Yi-Chin; Fan, Jiwen; Zhang, Guang J.; Xu, Kuan-Man; Ghan, Steven J.

    2015-04-01

    Following Part I, in which 3-D cloud-resolving model (CRM) simulations of a squall line and mesoscale convective complex in the midlatitude continental and the tropical regions are conducted and evaluated, we examine the scale dependence of eddy transport of water vapor, evaluate different eddy transport formulations, and improve the representation of convective transport across all scales by proposing a new formulation that more accurately represents the CRM-calculated eddy flux. CRM results show that there are strong grid-spacing dependencies of updraft and downdraft fractions regardless of altitudes, cloud life stage, and geographical location. As for the eddy transport of water vapor, updraft eddy flux is a major contributor to total eddy flux in the lower and middle troposphere. However, downdraft eddy transport can be as large as updraft eddy transport in the lower atmosphere especially at the mature stage of midlatitude continental convection. We show that the single-updraft approach significantly underestimates updraft eddy transport of water vapor because it fails to account for the large internal variability of updrafts, while a single downdraft represents the downdraft eddy transport of water vapor well. We find that using as few as three updrafts can account for the internal variability of updrafts well. Based on the evaluation with the CRM simulated data, we recommend a simplified eddy transport formulation that considers three updrafts and one downdraft. Such formulation is similar to the conventional one but much more accurately represents CRM-simulated eddy flux across all grid scales.

  1. Correcting orbital drift signal in the time series of AVHRR derived convective cloud fraction using rotated empirical orthogonal function

    Directory of Open Access Journals (Sweden)

    A. Devasthale

    2012-02-01

    Full Text Available The Advanced Very High Resolution Radiometer (AVHRR instruments onboard the series of National Oceanic and Atmospheric Administration (NOAA satellites offer the longest available meteorological data records from space. These satellites have drifted in orbit resulting in shifts in the local time sampling during the life span of the sensors onboard. Depending upon the amplitude of the diurnal cycle of the geophysical parameters derived, orbital drift may cause spurious trends in their time series. We investigate tropical deep convective clouds, which show pronounced diurnal cycle amplitude, to estimate an upper bound of the impact of orbital drift on their time series. We carry out a rotated empirical orthogonal function analysis (REOF and show that the REOFs are useful in delineating orbital drift signal and, more importantly, in subtracting this signal in the time series of convective cloud amount. These results will help facilitate the derivation of homogenized data series of cloud amount from NOAA satellite sensors and ultimately analyzing trends from them. However, we suggest detailed comparison of various methods and rigorous testing thereof applying final orbital drift corrections.

  2. The Microphysical Properties of Convective Precipitation Over the Tibetan Plateau by a Subkilometer Resolution Cloud-Resolving Simulation

    Science.gov (United States)

    Gao, Wenhua; Liu, Liping; Li, Jian; Lu, Chunsong

    2018-03-01

    The microphysical properties of convective precipitation over the Tibetan Plateau are unique because of the extremely high topography and special atmospheric conditions. In this study, the ground-based cloud radar and disdrometer observations as well as high-resolution Weather Research and Forecasting simulations with the Chinese Academy of Meteorological Sciences microphysics and four other microphysical schemes are used to investigate the microphysics and precipitation mechanisms of a convection event on 24 July 2014. The Weather Research and Forecasting-Chinese Academy of Meteorological Sciences simulation reasonably reproduces the spatial distribution of 24-hr accumulated rainfall, yet the temporal evolution of rain rate has a delay of 1-3 hr. The model reflectivity shares the common features with the cloud radar observations. The simulated raindrop size distributions demonstrate more of small- and large-size raindrops produced with the increase of rain rate, suggesting that changeable shape parameter should be used in size distribution. Results show that abundant supercooled water exists through condensation of water vapor above the freezing layer. The prevailing ice crystal microphysical processes are depositional growth and autoconversion of ice crystal to snow. The dominant source term of snow/graupel is riming of supercooled water. Sedimentation of graupel can play a vital role in the formation of precipitation, but melting of snow is rather small and quite different from that in other regions. Furthermore, water vapor budgets suggest that surface moisture flux be the principal source of water vapor and self-circulation of moisture happen at the beginning of convection, while total moisture flux convergence determine condensation and precipitation during the convective process over the Tibetan Plateau.

  3. Substantial convection and precipitation enhancements by ultrafine aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jiwen; Rosenfeld, Daniel; Zhang, Yuwei; Giangrande, Scott E.; Li, Zhanqing; Machado, Luiz A. T.; Martin, Scot T.; Yang, Yan; Wang, Jian; Artaxo, Paulo; Barbosa, Henrique M. J.; Braga, Ramon C.; Comstock, Jennifer M.; Feng, Zhe; Gao, Wenhua; Gomes, Helber B.; Mei, Fan; Pöhlker, Christopher; Pöhlker, Mira L.; Pöschl, Ulrich; de Souza, Rodrigo A. F.

    2018-01-25

    Aerosol-cloud interaction remains the largest uncertainty in climate projections. Ultrafine aerosol particles (UAP; size <50nm) are considered too small to serve as cloud condensation nuclei conventionally. However, this study provides observational evidence to accompany insights from numerical simulations to support that deep convective clouds (DCCs) over Amazon have strong capability of nucleating UAP from an urban source and forming greater numbers of droplets, because fast drop coalescence in these DCCs reduces drop surface area available for condensation, leading to high vapor supersaturation. The additional droplets subsequently decrease supersaturation and release more condensational latent heating, a dominant contributor to convection intensification, whereas enhanced latent heat from ice-related processes plays a secondary role. Therefore, the addition of anthropogenic UAP may play a much greater role in modulating clouds than previously believed over the Amazon region and possibly in other relatively pristine regions such as maritime and forest locations.

  4. The morphological evolution and internal convection of ExB-drifting plasma clouds: Theory, dielectric-in-cell simulations, and N-body dielectric simulations

    International Nuclear Information System (INIS)

    Borovsky, J.E.; Hansen, P.J.

    1998-01-01

    The evolution of ExB-drifting plasma clouds is investigated with the aid of a computational technique denoted here as open-quotes dielectric-in-cell.close quotes Many of the familiar phenomena associated with clouds of collisionless plasma are seen and explained and less-well-known phenomena associated with convection patterns, with the stripping of cloud material, and with the evolution of plasma clouds composed of differing ion species are investigated. The effects of spatially uniform diffusion are studied with the dielectric-in-cell technique and with another computational technique denoted as open-quotes N-body dielectric;close quotes the suppression of convection, the suppression of structure growth, the increase in material stripping, and the evolution of cloud anisotropy are examined. copyright 1998 American Institute of Physics

  5. FlorNExT®, a cloud computing application to estimate growth and yield of maritime pine (Pinus pinaster Ait.) stands in Northeastern Portugal

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro, S.; Rua, J.; Tomé, M.

    2016-07-01

    Aim of the study. To introduce and describe FlorNExT®, a free cloud computing application to estimate growth and yield of maritime pine (Pinus pinaster Ait.) even-aged stands in the Northeast of Portugal (NE Portugal). Area of study: NE Portugal. Material and methods: FlorNExT® implements a dynamic growth and yield modelling framework which integrates transition functions for dominant height (site index curves) and basal area, as well as output functions for tree and stand volume, biomass, and carbon content. Main results: FlorNExT® is freely available from any device with an Internet connection at: http://flornext.esa.ipb.pt/. Research highlights: This application has been designed to make it possible for any stakeholder to easily estimate standing volume, biomass, and carbon content in maritime pine stands from stand data, as well as to estimate growth and yield based on four stand variables: age, density, dominant height, and basal area. FlorNExT® allows planning thinning treatments. FlorNExT® is a fundamental tool to support forest mobilization at local and regional scales in NE Portugal. (Author)

  6. Estimation of radiative forcing and chore length of shallow convective clouds (SCC) based on broadband pyranometer measurement network

    Science.gov (United States)

    Shi, H.

    2017-12-01

    We presented a method to identify and calculate cloud radiative forcing (CRF) and horizontal chore length (L) of shallow convective clouds (SCC) using a network of 9 broadband pyranometers. The analyzing data was collected from the SCC campaign during two years summers (2015 2016) at Baiqi site over Inner Mongolia grassland. The network of pyranometers was operated across a spatial domain covering 42.16-42.30° N and 114.83-114.98° E. The SCC detection method was verified by observer reports and cameras, which showed that the detection method and human observations were in agreement about 75 %. The differences between the SCC detection method and human observations can be responsible for following factors: 1) small or dissipating clouds can be neglected for the value of 1 min of temporal resolution of pyranometer; 2) human observation recorded weather conditions four times every day; 3) SCC was indistinguishable from coexistence of SCC and Cirrus (Ci); 4) the SCC detection method is weighted toward clouds crossing the sun's path, while the human observer can view clouds over the entire sky. The deviation of L can be attributed to two factors: 1) the accuracy of wind speed at height of SCC and the ratio of horizontal and vertical length play a key role in determine values of L; 2) the effect of variance of solar zenith angle can be negligible. The downwelling shortwave CRF of SCC was -134.1 Wm-2. The average value of L of SCC was 1129 m. Besides, the distribution of normalized cloud chore length agreed well with power-law fit.

  7. Individual aerosol particles in ambient and updraft conditions below convective cloud bases in the Oman mountain region

    Science.gov (United States)

    Semeniuk, T. A.; Bruintjes, R. T.; Salazar, V.; Breed, D. W.; Jensen, T. L.; Buseck, P. R.

    2014-03-01

    An airborne study of cloud microphysics provided an opportunity to collect aerosol particles in ambient and updraft conditions of natural convection systems for transmission electron microscopy (TEM). Particles were collected simultaneously on lacey carbon and calcium-coated carbon (Ca-C) TEM grids, providing information on particle morphology and chemistry and a unique record of the particle's physical state on impact. In total, 22 particle categories were identified, including single, coated, aggregate, and droplet types. The fine fraction comprised up to 90% mixed cation sulfate (MCS) droplets, while the coarse fraction comprised up to 80% mineral-containing aggregates. Insoluble (dry), partially soluble (wet), and fully soluble particles (droplets) were recorded on Ca-C grids. Dry particles were typically silicate grains; wet particles were mineral aggregates with chloride, nitrate, or sulfate components; and droplets were mainly aqueous NaCl and MCS. Higher numbers of droplets were present in updrafts (80% relative humidity (RH)) compared with ambient conditions (60% RH), and almost all particles activated at cloud base (100% RH). Greatest changes in size and shape were observed in NaCl-containing aggregates (>0.3 µm diameter) along updraft trajectories. Their abundance was associated with high numbers of cloud condensation nuclei (CCN) and cloud droplets, as well as large droplet sizes in updrafts. Thus, compositional dependence was observed in activation behavior recorded for coarse and fine fractions. Soluble salts from local pollution and natural sources clearly affected aerosol-cloud interactions, enhancing the spectrum of particles forming CCN and by forming giant CCN from aggregates, thus, making cloud seeding with hygroscopic flares ineffective in this region.

  8. Study of the Evolution of the Electric Structure of a Convective Cloud Using the Data of a Numerical Nonstationary Three-Dimensional Model

    Science.gov (United States)

    Veremey, N. E.; Dovgalyuk, Yu. A.; Zatevakhin, M. A.; Ignatyev, A. A.; Morozov, V. N.

    2014-04-01

    Numerical nonstationary three-dimensional model of a convective cloud with parameterized description of microphysical processes with allowance for the electrization processes is considered. The results of numerical modeling of the cloud evolution for the specified atmospheric conditions are presented. The spatio-temporal distribution of the main cloud characteristics including the volume charge density and the electric field is obtained. The calculation results show that the electric structure of the cloud is different at its various life stages, i.e., it varies from unipolar to dipolar and then to tripolar. This conclusion is in fair agreement with the field studies.

  9. Analysis of 35 GHz Cloud Radar polarimetric variables to identify stratiform and convective precipitation.

    Science.gov (United States)

    Fontaine, Emmanuel; Illingworth, Anthony, J.; Stein, Thorwald

    2017-04-01

    This study is performed using vertical profiles of radar measurements at 35GHz, for the period going from 29th of February to 1rst October 2016, at the Chilbolton observatory in United Kingdom. During this period, more than 40 days with precipitation events are investigated. The investigation uses the synergy of radar reflectivity factors, vertical velocity, Doppler spectrum width, and linear depolarization ratio (LDR) to differentiate between stratiform and convective rain events. The depth of the layer with Doppler spectrum width values greater than 0.5 m s-1 is shown to be a suitable proxy to distinguish between convective and stratiform events. Using LDR to detect the radar bright band, bright band characteristics such as depth of the layer and maximum LDR are shown to vary with the amount of turbulence aloft. Profiles of radar measurements are also compared to rain gauge measurements to study the contribution of convective and stratiform rainfall to total rain duration and amount. To conclude, this study points out differences between convective and stratiform rains and quantifies their contributions over a precipitation event, highlighting that convective and stratiform rainfall should be considered as a continuum rather than a dichotomy.

  10. A global lightning parameterization based on statistical relationships among environmental factors, aerosols, and convective clouds in the TRMM climatology

    Science.gov (United States)

    Stolz, Douglas C.; Rutledge, Steven A.; Pierce, Jeffrey R.; van den Heever, Susan C.

    2017-07-01

    The objective of this study is to determine the relative contributions of normalized convective available potential energy (NCAPE), cloud condensation nuclei (CCN) concentrations, warm cloud depth (WCD), vertical wind shear (SHEAR), and environmental relative humidity (RH) to the variability of lightning and radar reflectivity within convective features (CFs) observed by the Tropical Rainfall Measuring Mission (TRMM) satellite. Our approach incorporates multidimensional binned representations of observations of CFs and modeled thermodynamics, kinematics, and CCN as inputs to develop approximations for total lightning density (TLD) and the average height of 30 dBZ radar reflectivity (AVGHT30). The results suggest that TLD and AVGHT30 increase with increasing NCAPE, increasing CCN, decreasing WCD, increasing SHEAR, and decreasing RH. Multiple-linear approximations for lightning and radar quantities using the aforementioned predictors account for significant portions of the variance in the binned data set (R2 ≈ 0.69-0.81). The standardized weights attributed to CCN, NCAPE, and WCD are largest, the standardized weight of RH varies relative to other predictors, while the standardized weight for SHEAR is comparatively small. We investigate these statistical relationships for collections of CFs within various geographic areas and compare the aerosol (CCN) and thermodynamic (NCAPE and WCD) contributions to variations in the CF population in a partial sensitivity analysis based on multiple-linear regression approximations computed herein. A global lightning parameterization is developed; the average difference between predicted and observed TLD decreases from +21.6 to +11.6% when using a hybrid approach to combine separate approximations over continents and oceans, thus highlighting the need for regionally targeted investigations in the future.

  11. Relative humidity and its effect on aerosol optical depth in the vicinity of convective clouds

    International Nuclear Information System (INIS)

    Altaratz, O; Bar-Or, R Z; Wollner, U; Koren, I

    2013-01-01

    The hygroscopic growth of aerosols is controlled by the relative humidity (RH) and changes the aerosols’ physical and hence optical properties. Observational studies of aerosol–cloud interactions evaluate the aerosol concentration using optical parameters, such as the aerosol optical depth (AOD), which can be affected by aerosol humidification. In this study we evaluate the RH background and variance values, in the lower cloudy atmosphere, an additional source of variance in AOD values beside the natural changes in aerosol concentration. In addition, we estimate the bias in RH and AOD, related to cloud thickness. This provides the much needed range of RH-related biases in studies of aerosol–cloud interaction. Twelve years of radiosonde measurements (June–August) in thirteen globally distributed stations are analyzed. The estimated non-biased AOD variance due to day-to-day changes in RH is found to be around 20% and the biases linked to cloud development around 10%. Such an effect is important and should be considered in direct and indirect aerosol effect estimations but it is inadequate to account for most of the AOD trend found in observational studies of aerosol–cloud interactions. (letter)

  12. Variability of oceanic deep convective system vertical structures observed by CloudSat in Indo-Pacific regions associated with the Madden-Julian oscillation

    Science.gov (United States)

    Yuan, Jian

    2016-09-01

    Vertical structures of deep convective systems during the Madden-Julian oscillation (MJO) are investigated using CloudSat radar measurements in Indo-Pacific oceanic areas. In active phases of the MJO, relatively more large systems and connected mesoscale convective systems (CMCSs) occur. The occurrence frequency of CMCSs peaks in the onset phase, a phase earlier than separated mesoscale convective systems (SMCSs). Compared with SMCSs, CMCSs of all sizes have weaker reflectivity above 8 km in their deep precipitating portions and thick anvil clouds closely linked to them, suggesting more "stratiform" physics associated with them. SMCSs and CMCSs together produce relatively the least anvil clouds in the onset phase, while their deep precipitating portions show stronger/weaker reflectivity above 8 km before/after the onset phase. Thus, after the onset phase of the MJO, mesoscale convective systems shift toward a more "convective" organization because SMCSs maximize after the onset, while their internal structures appear more stratiform because internally they have weaker reflectivity above 8 km. CMCSs coincide with a more humid middle troposphere spatially, even at the same locations a few days before they occur. Middle-tropospheric moistening peaks in the onset phase. Moistening of the free troposphere around deep convective systems shows relatively stronger moistening/drying below 700 hPa before/after the onset phase than domain-mean averages. Low-topped clouds occur most frequently around CMCSs and in active phases, consistent with the presence of a moister free troposphere. Coexistence of these phenomena suggests that the role of middle troposphere moisture in the formation of CMCSs should be better understood.

  13. A study of the relationship between cloud-to-ground lightning and precipitation in the convective weather system in China

    Directory of Open Access Journals (Sweden)

    Y. Zhou

    Full Text Available In this paper, the correlation between cloud-to-ground (CG lightning and precipitation has been studied by making use of the data from weather radar, meteorological soundings, and a lightning location system that includes three direction finders about 40 km apart from each other in the Pingliang area of east Gansu province in P. R. China. We have studied the convective systems that developed during two cold front processes passing over the observation area, and found that the CG lightning can be an important factor in the precipitation estimation. The regression equation between the average precipitation intensity (R and the number of CG lightning flashes (L in the main precipitation period is R = 1.69 ln (L - 0.27, and the correlation coefficient r is 0.86. The CG lightning flash rate can be used as an indicator of the formation and development of the convective weather system. Another more exhaustive precipitation estimation method has been developed by analyzing the temporal and spatial distributions of the precipitation relative to the location of the CG lightning flashes. Precipitation calculated from the CG lightning flashes is very useful, especially in regions with inadequate radar cover.

    Key words. Meteorology and atmospheric dynamics (atmospheric electricity; lightning; precipitation

  14. Nowcasting of deep convective clouds and heavy precipitation: Comparison study between NWP model simulation and extrapolation

    Czech Academy of Sciences Publication Activity Database

    Bližňák, Vojtěch; Sokol, Zbyněk; Zacharov, Petr, jr.

    2017-01-01

    Roč. 184, February (2017), s. 24-34 ISSN 0169-8095 R&D Projects: GA ČR(CZ) GPP209/12/P701; GA ČR GA13-34856S Institutional support: RVO:68378289 Keywords : meteorological satellite * convective storm * NWP model * verification * Czech Republic Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 3.778, year: 2016 http://www.sciencedirect.com/science/article/pii/S0169809516304288

  15. Improvement of Systematic Bias of mean state and the intraseasonal variability of CFSv2 through superparameterization and revised cloud-convection-radiation parameterization

    Science.gov (United States)

    Mukhopadhyay, P.; Phani Murali Krishna, R.; Goswami, Bidyut B.; Abhik, S.; Ganai, Malay; Mahakur, M.; Khairoutdinov, Marat; Dudhia, Jimmy

    2016-05-01

    Inspite of significant improvement in numerical model physics, resolution and numerics, the general circulation models (GCMs) find it difficult to simulate realistic seasonal and intraseasonal variabilities over global tropics and particularly over Indian summer monsoon (ISM) region. The bias is mainly attributed to the improper representation of physical processes. Among all the processes, the cloud and convective processes appear to play a major role in modulating model bias. In recent times, NCEP CFSv2 model is being adopted under Monsoon Mission for dynamical monsoon forecast over Indian region. The analyses of climate free run of CFSv2 in two resolutions namely at T126 and T382, show largely similar bias in simulating seasonal rainfall, in capturing the intraseasonal variability at different scales over the global tropics and also in capturing tropical waves. Thus, the biases of CFSv2 indicate a deficiency in model's parameterization of cloud and convective processes. Keeping this in background and also for the need to improve the model fidelity, two approaches have been adopted. Firstly, in the superparameterization, 32 cloud resolving models each with a horizontal resolution of 4 km are embedded in each GCM (CFSv2) grid and the conventional sub-grid scale convective parameterization is deactivated. This is done to demonstrate the role of resolving cloud processes which otherwise remain unresolved. The superparameterized CFSv2 (SP-CFS) is developed on a coarser version T62. The model is integrated for six and half years in climate free run mode being initialised from 16 May 2008. The analyses reveal that SP-CFS simulates a significantly improved mean state as compared to default CFS. The systematic bias of lesser rainfall over Indian land mass, colder troposphere has substantially been improved. Most importantly the convectively coupled equatorial waves and the eastward propagating MJO has been found to be simulated with more fidelity in SP-CFS. The reason of

  16. The Impact of the Diurnal Cycle of Clouds and Precipitation over the Maritime Continent on the Propagation of the MJO into the Western Pacific

    Science.gov (United States)

    Burleyson, C. D.; Hagos, S. M.; Feng, Z.

    2016-12-01

    The processes that determine the interaction between the islands of the maritime continent (MC) and the eastward propagation of the Madden-Julian Oscillation (MJO) are poorly understood. We are undertaking a series of observational and modeling analyses aimed at understanding how clouds and precipitation over the islands of the MC lead to changes in the intensity of the MJO (inferred by the amplitude of the Real-time Multivariate MJO index [RMM] and other metrics) as it crosses the MC. One component of our analysis uses the long-term measurements from the DOE Atmospheric Radiation Measurement (ARM) sites in the Tropical Western Pacific (TWP) to examine cloud radiative effects as the MJO crosses the MC. Using the multi-year ARM dataset and a cloud resolving model (CRM), we show that the MJO interacts with the diurnal cycle of surface heating, clouds, and precipitation over the islands of the MC in a way that weakens it. Additionally, using a satellite climatology based on the TRMM 3B42 dataset we found that MJO episodes that weaken as they cross the MC are characterized by more frequent precipitation and warmer sea surface temperatures (SSTs) south of the equator and less frequent precipitation north of the equator compared to cases where the MJO intensifies. The north-south polarity in SSTs suggests a seasonal dependence in the ability of the MJO to cross the MC. This seasonality was confirmed by looking the seasonal distribution of changes in MJO amplitude as it crosses the MC. Consistent with the SST result, we found that MJO episodes that intensify as they cross the MC are more likely to occur during the northern hemisphere summer and less likely to occur during the northern hemisphere winter (Fig. 1). A regional CRM and satellite observations are used jointly to explore the processes responsible for this seasonality and to examine the impact of interannual oscillations such as ENSO and monsoons on the ability of the MJO to cross the MC. Fig. 1. The annual

  17. Maritime Technology

    DEFF Research Database (Denmark)

    Sørensen, Herman

    1997-01-01

    Elementary introduction to the subject "Maritime Technology".The contents include drawings, sketches and references in English without any supplementary text.......Elementary introduction to the subject "Maritime Technology".The contents include drawings, sketches and references in English without any supplementary text....

  18. Effects of turbulence on mixed-phase deep convective clouds under different basic-state winds and aerosol concentrations

    Science.gov (United States)

    Lee, Hyunho; Baik, Jong-Jin; Han, Ji-Young

    2014-12-01

    The effects of turbulence-induced collision enhancement (TICE) on mixed-phase deep convective clouds are numerically investigated using a 2-D cloud model with bin microphysics for uniform and sheared basic-state wind profiles and different aerosol concentrations. Graupel particles account for the most of the cloud mass in all simulation cases. In the uniform basic-state wind cases, graupel particles with moderate sizes account for some of the total graupel mass in the cases with TICE, whereas graupel particles with large sizes account for almost all the total graupel mass in the cases without TICE. This is because the growth of ice crystals into small graupel particles is enhanced due to TICE. The changes in the size distributions of graupel particles due to TICE result in a decrease in the mass-averaged mean terminal velocity of graupel particles. Therefore, the downward flux of graupel mass, and thus the melting of graupel particles, is reduced due to TICE, leading to a decrease in the amount of surface precipitation. Moreover, under the low aerosol concentration, TICE increases the sublimation of ice particles, consequently playing a partial role in reducing the amount of surface precipitation. The effects of TICE are less pronounced in the sheared basic-state wind cases than in the uniform basic-state wind cases because the number of ice crystals is much smaller in the sheared basic-state wind cases than in the uniform basic-state wind cases. Thus, the size distributions of graupel particles in the cases with and without TICE show little difference.

  19. Jupiter cloud composition, stratification, convection, and wave motion: a view from new horizons.

    Science.gov (United States)

    Reuter, D C; Simon-Miller, A A; Lunsford, A; Baines, K H; Cheng, A F; Jennings, D E; Olkin, C B; Spencer, J R; Stern, S A; Weaver, H A; Young, L A

    2007-10-12

    Several observations of Jupiter's atmosphere made by instruments on the New Horizons spacecraft have implications for the stability and dynamics of Jupiter's weather layer. Mesoscale waves, first seen by Voyager, have been observed at a spatial resolution of 11 to 45 kilometers. These waves have a 300-kilometer wavelength and phase velocities greater than the local zonal flow by 100 meters per second, much higher than predicted by models. Additionally, infrared spectral measurements over five successive Jupiter rotations at spatial resolutions of 200 to 140 kilometers have shown the development of transient ammonia ice clouds (lifetimes of 40 hours or less) in regions of strong atmospheric upwelling. Both of these phenomena serve as probes of atmospheric dynamics below the visible cloud tops.

  20. Constraining mass-diameter relations from hydrometeor images and cloud radar reflectivities in tropical continental and oceanic convective anvils

    Science.gov (United States)

    Fontaine, E.; Schwarzenboeck, A.; Delanoë, J.; Wobrock, W.; Leroy, D.; Dupuy, R.; Gourbeyre, C.; Protat, A.

    2014-10-01

    In this study the density of ice hydrometeors in tropical clouds is derived from a combined analysis of particle images from 2-D-array probes and associated reflectivities measured with a Doppler cloud radar on the same research aircraft. Usually, the mass-diameter m(D) relationship is formulated as a power law with two unknown coefficients (pre-factor, exponent) that need to be constrained from complementary information on hydrometeors, where absolute ice density measurement methods do not apply. Here, at first an extended theoretical study of numerous hydrometeor shapes simulated in 3-D and arbitrarily projected on a 2-D plan allowed to constrain the exponent βof the m(D) relationship from the exponent σ of the surface-diameterS(D)relationship, which is likewise written as a power law. Since S(D) always can be determined for real data from 2-D optical array probes or other particle imagers, the evolution of the m(D) exponent can be calculated. After that, the pre-factor α of m(D) is constrained from theoretical simulations of the radar reflectivities matching the measured reflectivities along the aircraft trajectory. The study was performed as part of the Megha-Tropiques satellite project, where two types of mesoscale convective systems (MCS) were investigated: (i) above the African continent and (ii) above the Indian Ocean. For the two data sets, two parameterizations are derived to calculate the vertical variability of m(D) coefficients α and β as a function of the temperature. Originally calculated (with T-matrix) and also subsequently parameterized m(D) relationships from this study are compared to other methods (from literature) of calculating m(D) in tropical convection. The significant benefit of using variable m(D) relations instead of a single m(D) relationship is demonstrated from the impact of all these m(D) relations on Z-CWC (Condensed Water Content) and Z-CWC-T-fitted parameterizations.

  1. The role of 1-D and 3-D radiative heating in the organization of shallow cumulus convection and the formation of cloud streets

    Science.gov (United States)

    Jakub, Fabian; Mayer, Bernhard

    2017-11-01

    The formation of shallow cumulus cloud streets was historically attributed primarily to dynamics. Here, we focus on the interaction between radiatively induced surface heterogeneities and the resulting patterns in the flow. Our results suggest that solar radiative heating has the potential to organize clouds perpendicular to the sun's incidence angle. To quantify the extent of organization, we performed a high-resolution large-eddy simulation (LES) parameter study. We varied the horizontal wind speed, the surface heat capacity, the solar zenith and azimuth angles, and radiative transfer parameterizations (1-D and 3-D). As a quantitative measure we introduce a simple algorithm that provides a scalar quantity for the degree of organization and the alignment. We find that, even in the absence of a horizontal wind, 3-D radiative transfer produces cloud streets perpendicular to the sun's incident direction, whereas the 1-D approximation or constant surface fluxes produce randomly positioned circular clouds. Our reasoning for the enhancement or reduction of organization is the geometric position of the cloud's shadow and its corresponding surface fluxes. Furthermore, when increasing horizontal wind speeds to 5 or 10 m s-1, we observe the development of dynamically induced cloud streets. If, in addition, solar radiation illuminates the surface beneath the cloud, i.e., when the sun is positioned orthogonally to the mean wind field and the solar zenith angle is larger than 20°, the cloud-radiative feedback has the potential to significantly enhance the tendency to organize in cloud streets. In contrast, in the case of the 1-D approximation (or overhead sun), the tendency to organize is weaker or even prohibited because the shadow is cast directly beneath the cloud. In a land-surface-type situation, we find the organization of convection happening on a timescale of half an hour. The radiative feedback, which creates surface heterogeneities, is generally diminished for large

  2. The role of 1-D and 3-D radiative heating in the organization of shallow cumulus convection and the formation of cloud streets

    Directory of Open Access Journals (Sweden)

    F. Jakub

    2017-11-01

    Full Text Available The formation of shallow cumulus cloud streets was historically attributed primarily to dynamics. Here, we focus on the interaction between radiatively induced surface heterogeneities and the resulting patterns in the flow. Our results suggest that solar radiative heating has the potential to organize clouds perpendicular to the sun's incidence angle. To quantify the extent of organization, we performed a high-resolution large-eddy simulation (LES parameter study. We varied the horizontal wind speed, the surface heat capacity, the solar zenith and azimuth angles, and radiative transfer parameterizations (1-D and 3-D. As a quantitative measure we introduce a simple algorithm that provides a scalar quantity for the degree of organization and the alignment. We find that, even in the absence of a horizontal wind, 3-D radiative transfer produces cloud streets perpendicular to the sun's incident direction, whereas the 1-D approximation or constant surface fluxes produce randomly positioned circular clouds. Our reasoning for the enhancement or reduction of organization is the geometric position of the cloud's shadow and its corresponding surface fluxes. Furthermore, when increasing horizontal wind speeds to 5 or 10 m s−1, we observe the development of dynamically induced cloud streets. If, in addition, solar radiation illuminates the surface beneath the cloud, i.e., when the sun is positioned orthogonally to the mean wind field and the solar zenith angle is larger than 20°, the cloud-radiative feedback has the potential to significantly enhance the tendency to organize in cloud streets. In contrast, in the case of the 1-D approximation (or overhead sun, the tendency to organize is weaker or even prohibited because the shadow is cast directly beneath the cloud. In a land-surface-type situation, we find the organization of convection happening on a timescale of half an hour. The radiative feedback, which creates surface heterogeneities, is

  3. Using a second-order turbulence radiative-convective model to study the cloud/radiation interaction with the FIRE data

    International Nuclear Information System (INIS)

    Kao, C.Y.J.

    1992-01-01

    It is well recognized that extended sheets of low-level stratus and stratocumulus clouds are a persistent feature over the eastern parts of the major ocean basins associated with the quasipermanent subtropical high-pressure systems. These clouds exert a strong influence on climate through their high albedo, compared with the underlying surface, and their low altitude. The former leads to a reduction of the net incoming shortwave flux into the atmosphere and the latter leads to an infrared loss in a way essentially the same as the cloud-free conditions. Randall et al.[1984] estimated that an increase of a few percent of global low-level stratiform clouds may offset the warming caused by a doubling of the atmos-pheric CO 2 . The Atmospheric Radiation Measure-ment (ARM) Program, sponsored by the US Department of Energy, is envisioning a locale in the Eastern North Pacific for extensive measure-ments of stratiform boundary-layer clouds and their interaction with atmospheric radiation. Thus, a physically-based parameterization sheme for marine low-level stratiform clouds can be developed for general circulation models (GCMs). This paper is a modeling study with the current understanding of the important physical processes associated with a cloud-capped boundary layer. The numerical model is a high-resolution one-dimensional version of the second-order turbulence convective/radiative model developed at the Los Alamos National Laboratory

  4. Cloud-resolving model intercomparison of an MC3E squall line case: Part I-Convective updrafts: CRM Intercomparison of a Squall Line

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jiwen [Pacific Northwest National Laboratory, Richland Washington USA; Han, Bin [Pacific Northwest National Laboratory, Richland Washington USA; School of Atmospheric Sciences, Nanjing University, Nanjing China; Varble, Adam [Department of Atmospheric Sciences, University of Utah, Salt Lake City Utah USA; Morrison, Hugh [National Center for Atmospheric Research, Boulder Colorado USA; North, Kirk [Department of Atmospheric and Oceanic Sciences, McGill University, Montreal Quebec USA; Kollias, Pavlos [Department of Atmospheric and Oceanic Sciences, McGill University, Montreal Quebec USA; School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook New York USA; Chen, Baojun [School of Atmospheric Sciences, Nanjing University, Nanjing China; Dong, Xiquan [Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson Arizona USA; Giangrande, Scott E. [Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton New York USA; Khain, Alexander [The Institute of the Earth Science, The Hebrew University of Jerusalem, Jerusalem Israel; Lin, Yun [Department of Atmospheric Sciences, Texas A& M University, College Station Texas USA; Mansell, Edward [NOAA/OAR/National Severe Storms Laboratory, Norman Oklahoma USA; Milbrandt, Jason A. [Meteorological Research Division, Environment and Climate Change Canada, Dorval Canada; Stenz, Ronald [Department of Atmospheric Sciences, University of North Dakota, Grand Forks North Dakota USA; Thompson, Gregory [National Center for Atmospheric Research, Boulder Colorado USA; Wang, Yuan [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena California USA

    2017-09-06

    A constrained model intercomparison study of a mid-latitude mesoscale squall line is performed using the Weather Research & Forecasting (WRF) model at 1-km horizontal grid spacing with eight cloud microphysics schemes, to understand specific processes that lead to the large spread of simulated cloud and precipitation at cloud-resolving scales, with a focus of this paper on convective cores. Various observational data are employed to evaluate the baseline simulations. All simulations tend to produce a wider convective area than observed, but a much narrower stratiform area, with most bulk schemes overpredicting radar reflectivity. The magnitudes of the virtual potential temperature drop, pressure rise, and the peak wind speed associated with the passage of the gust front are significantly smaller compared with the observations, suggesting simulated cool pools are weaker. Simulations also overestimate the vertical velocity and Ze in convective cores as compared with observational retrievals. The modeled updraft velocity and precipitation have a significant spread across the eight schemes even in this strongly dynamically-driven system. The spread of updraft velocity is attributed to the combined effects of the low-level perturbation pressure gradient determined by cold pool intensity and buoyancy that is not necessarily well correlated to differences in latent heating among the simulations. Variability of updraft velocity between schemes is also related to differences in ice-related parameterizations, whereas precipitation variability increases in no-ice simulations because of scheme differences in collision-coalescence parameterizations.

  5. Aerosol transport and wet scavenging in deep convective clouds: a case study and model evaluation using a multiple passive tracer analysis approach

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qing; Easter, Richard C.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Fast, Jerome D.; Ghan, Steven J.; Wang, Hailong; Berg, Larry K.; Barth, Mary; Liu, Ying; Shrivastava, ManishKumar B.; Singh, Balwinder; Morrison, H.; Fan, Jiwen; Ziegler, Conrad L.; Bela, Megan; Apel, Eric; Diskin, G. S.; Mikoviny, Tomas; Wisthaler, Armin

    2015-08-20

    The effect of wet scavenging on ambient aerosols in deep, continental convective clouds in the mid-latitudes is studied for a severe storm case in Oklahoma during the Deep Convective Clouds and Chemistry (DC3) field campaign. A new passive-tracer based transport analysis framework is developed to characterize the convective transport based on the vertical distribution of several slowly reacting and nearly insoluble trace gases. The passive gas concentration in the upper troposphere convective outflow results from a mixture of 47% from the lower level (0-3 km), 21% entrained from the upper troposphere, and 32% from mid-atmosphere based on observations. The transport analysis framework is applied to aerosols to estimate aerosol transport and wet-scavenging efficiency. Observations yield high overall scavenging efficiencies of 81% and 68% for aerosol mass (Dp < 1μm) and aerosol number (0.03< Dp < 2.5μm), respectively. Little chemical selectivity to wet scavenging is seen among observed submicron sulfate (84%), organic (82%), and ammonium (80%) aerosols, while nitrate has a much lower scavenging efficiency of 57% likely due to the uptake of nitric acid. Observed larger size particles (0.15 - 2.5μm) are scavenged more efficiently (84%) than smaller particles (64%; 0.03 - 0.15μm). The storm is simulated using the chemistry version of the WRF model. Compared to the observation based analysis, the standard model underestimates the wet scavenging efficiency for both mass and number concentrations with low biases of 31% and 40%, respectively. Adding a new treatment of secondary activation significantly improves simulation results, so that the bias in scavenging efficiency in mass and number concentrations is reduced to <10%. This supports the hypothesis that secondary activation is an important process for wet removal of aerosols in deep convective storms.

  6. Variability of Oceanic Mesoscale Convective System Vertical Structures Observed by CloudSat in Indo-Pacific Regions Associated with the Madden-Julian Oscillation

    Science.gov (United States)

    Yuan, J.

    2016-12-01

    Vertical structures of mesoscale convective systems (MCSs) during the Madden-Julian-Oscillation (MJO) are investigated using 2006-2011 CloudSat radar measurements for Indo-Pacific oceanic areas. In active phases of the MJO relatively more large MCSs and connected MCSs occur. The frequency of occurrence of connected MCSs peaks in the onset phase, a phase earlier than separated MCSs. Compared to separated MCSs, connected MCSs in all sizes have weaker reflectivity above 8 km in their deep precipitating portions and thick anvil clouds closely linked to them, suggesting more "stratiform" physics associated with them. Separated MCSs and connected MCSs together produce relatively the least anvil clouds in the onset phase while their deep precipitating portions show stronger/weaker reflectivity above 8 km before/after the onset phase. Thus after the onset phase of the MJO, MCSs shift toward more "convective" organization because separated MCSs maximize after the onset, while their internal structures appear more "stratiform" because internally they have weaker reflectivity above 8km. Connected MCSs coincide with a more humid middle troposphere spatially, even at the same places a few days before they occur. Middle-tropospheric moistening peaks in the onset phase. Moistening of the free troposphere around deep convective systems shows relatively stronger moistening/drying below the 700 hPa before/after the onset phase compared to domain-mean averages. Lower-topped clouds occur most frequently around CMCSs and in active phases, consistent with the presence of a moister free troposphere. Coexistence of these phenomena suggests that the role of middle troposphere moisture in the formation of CMCSs needs to be better understood.

  7. Competition between core and periphery-based processes in warm convective clouds – from invigoration to suppression

    OpenAIRE

    G. Dagan; I. Koren; O. Altaratz

    2015-01-01

    How do changes in the amount and properties of aerosol affect warm clouds? Recent studies suggest that they have opposing effects. Some suggest that an increase in aerosol loading leads to enhanced evaporation and therefore smaller clouds, whereas other studies suggest clouds' invigoration. In this study, using an axisymmetric bin-microphysics cloud model, we propose a theoretical scheme that analyzes the evolution of key processes in warm clouds, under different aerosol loa...

  8. Aerosol properties and their impacts on surface CCN at the ARM Southern Great Plains site during the 2011 Midlatitude Continental Convective Clouds Experiment

    Science.gov (United States)

    Logan, Timothy; Dong, Xiquan; Xi, Baike

    2018-02-01

    Aerosol particles are of particular importance because of their impacts on cloud development and precipitation processes over land and ocean. Aerosol properties as well as meteorological observations from the Department of Energy Atmospheric Radiation Measurement (ARM) platform situated in the Southern Great Plains (SGP) are utilized in this study to illustrate the dependence of continental cloud condensation nuclei (CCN) number concentration ( N CCN) on aerosol type and transport pathways. ARM-SGP observations from the 2011 Midlatitude Continental Convective Clouds Experiment field campaign are presented in this study and compared with our previous work during the 2009-10 Clouds, Aerosol, and Precipitation in the Marine Boundary Layer field campaign over the current ARM Eastern North Atlantic site. Northerly winds over the SGP reflect clean, continental conditions with aerosol scattering coefficient ( σ sp) values less than 20 Mm-1 and N CCN values less than 100 cm-3. However, southerly winds over the SGP are responsible for the observed moderate to high correlation ( R) among aerosol loading ( σ sp moisture via the Gulf of Mexico, indicating a strong dependence on air mass type. NASA MERRA-2 reanalysis aerosol and chemical data are moderately to highly correlated with surface ARM-SGP data, suggesting that this facility can represent surface aerosol conditions in the SGP, especially during strong aerosol loading events that transport via the Gulf of Mexico. Future long-term investigations will help to understand the seasonal influences of air masses on aerosol, CCN, and cloud properties over land in comparison to over ocean.

  9. Evaluating Lightning-generated NOx (LNOx) Parameterization based on Cloud Top Height at Resolutions with Partially-resolved Convection for Upper Tropospheric Chemistry Studies

    Science.gov (United States)

    Wong, J.; Barth, M. C.; Noone, D. C.

    2012-12-01

    Lightning-generated nitrogen oxides (LNOx) is an important precursor to tropospheric ozone production. With a meteorological time-scale variability similar to that of the ozone chemical lifetime, it can nonlinearly perturb tropospheric ozone concentration. Coupled with upper-air circulation patterns, LNOx can accumulate in significant amount in the upper troposphere with other precursors, thus enhancing ozone production (see attached figure). While LNOx emission has been included and tuned extensively in global climate models, its inclusions in regional chemistry models are seldom tested. Here we present a study that evaluates the frequently used Price and Rind parameterization based on cloud-top height at resolutions that partially resolve deep convection using the Weather Research and Forecasting model with Chemistry (WRF-Chem) over the contiguous United States. With minor modifications, the parameterization is shown to generate integrated flash counts close to those observed. However, the modeled frequency distribution of cloud-to-ground flashes do not represent well for storms with high flash rates, bringing into question the applicability of the intra-cloud/ground partitioning (IC:CG) formulation of Price and Rind in some studies. Resolution dependency also requires attention when sub-grid cloud-tops are used instead of the originally intended grid-averaged cloud-top. LNOx passive tracers being gathered by monsoonal upper tropospheric anticyclone.

  10. Physical Validation of GPM Retrieval Algorithms Over Land: An Overview of the Mid-Latitude Continental Convective Clouds Experiment (MC3E)

    Science.gov (United States)

    Petersen, Walter A.; Jensen, Michael P.

    2011-01-01

    The joint NASA Global Precipitation Measurement (GPM) -- DOE Atmospheric Radiation Measurement (ARM) Midlatitude Continental Convective Clouds Experiment (MC3E) was conducted from April 22-June 6, 2011, centered on the DOE-ARM Southern Great Plains Central Facility site in northern Oklahoma. GPM field campaign objectives focused on the collection of airborne and ground-based measurements of warm-season continental precipitation processes to support refinement of GPM retrieval algorithm physics over land, and to improve the fidelity of coupled cloud resolving and land-surface satellite simulator models. DOE ARM objectives were synergistically focused on relating observations of cloud microphysics and the surrounding environment to feedbacks on convective system dynamics, an effort driven by the need to better represent those interactions in numerical modeling frameworks. More specific topics addressed by MC3E include ice processes and ice characteristics as coupled to precipitation at the surface and radiometer signals measured in space, the correlation properties of rainfall and drop size distributions and impacts on dual-frequency radar retrieval algorithms, the transition of cloud water to rain water (e.g., autoconversion processes) and the vertical distribution of cloud water in precipitating clouds, and vertical draft structure statistics in cumulus convection. The MC3E observational strategy relied on NASA ER-2 high-altitude airborne multi-frequency radar (HIWRAP Ka-Ku band) and radiometer (AMPR, CoSMIR; 10-183 GHz) sampling (a GPM "proxy") over an atmospheric column being simultaneously profiled in situ by the University of North Dakota Citation microphysics aircraft, an array of ground-based multi-frequency scanning polarimetric radars (DOE Ka-W, X and C-band; NASA D3R Ka-Ku and NPOL S-bands) and wind-profilers (S/UHF bands), supported by a dense network of over 20 disdrometers and rain gauges, all nested in the coverage of a six-station mesoscale rawinsonde

  11. The interaction of a magnetic cloud with the Earth - Ionospheric convection in the Northern and Southern Hemispheres for a wide range of quasi-steady interplanetary magnetic field conditions

    Science.gov (United States)

    Freeman, M. P.; Farrugia, C. J.; Burlaga, L. F.; Hairston, M. R.; Greenspan, M. E.; Ruohoniemi, J. M.; Lepping, R. P.

    1993-01-01

    Observations are presented of the ionospheric convection in cross sections of the polar cap and auroral zone as part of the study of the interaction of the Earth's magnetosphere with the magnetic cloud of January 13-15, 1988. For strongly northward IMF, the convection in the Southern Hemisphere is characterized by a two-cell convection pattern comfined to high latitudes with sunward flow over the pole. The strength of the flows is comparable to that later seen under southward IMF. Superimposed on this convection pattern there are clear dawn-dusk asymmetries associated with a one-cell convection component whose sense depends on the polarity of the magnetic cloud's large east-west magnetic field component. When the cloud's magnetic field turns southward, the convection is characterized by a two-cell pattern extending to lower latitude with antisunward flow over the pole. There is no evident interhemispheric difference in the structure and strength of the convection. Superimposed dawn-dusk asymmetries in the flow patterns are observed which are only in part attributable to the east-west component of the magnetic field.

  12. Estimating effective particle size of tropical deep convective clouds with a look-up table method using satellite measurements of brightness temperature differences

    Science.gov (United States)

    Hong, Gang; Minnis, Patrick; Doelling, David; Ayers, J. Kirk; Sun-Mack, Szedung

    2012-03-01

    A method for estimating effective ice particle radius Re at the tops of tropical deep convective clouds (DCC) is developed on the basis of precomputed look-up tables (LUTs) of brightness temperature differences (BTDs) between the 3.7 and 11.0 μm bands. A combination of discrete ordinates radiative transfer and correlated k distribution programs, which account for the multiple scattering and monochromatic molecular absorption in the atmosphere, is utilized to compute the LUTs as functions of solar zenith angle, satellite zenith angle, relative azimuth angle, Re, cloud top temperature (CTT), and cloud visible optical thickness τ. The LUT-estimated DCC Re agrees well with the cloud retrievals of the Moderate Resolution Imaging Spectroradiometer (MODIS) for the NASA Clouds and Earth's Radiant Energy System with a correlation coefficient of 0.988 and differences of less than 10%. The LUTs are applied to 1 year of measurements taken from MODIS aboard Aqua in 2007 to estimate DCC Re and are compared to a similar quantity from CloudSat over the region bounded by 140°E, 180°E, 0°N, and 20°N in the Western Pacific Warm Pool. The estimated DCC Re values are mainly concentrated in the range of 25-45 μm and decrease with CTT. Matching the LUT-estimated Re with ice cloud Re retrieved by CloudSat, it is found that the ice cloud τ values from DCC top to the vertical location where LUT-estimated Re is located at the CloudSat-retrieved Re profile are mostly less than 2.5 with a mean value of about 1.3. Changes in the DCC τ can result in differences of less than 10% for Re estimated from LUTs. The LUTs of 0.65 μm bidirectional reflectance distribution function (BRDF) are built as functions of viewing geometry and column amount of ozone above upper troposphere. The 0.65 μm BRDF can eliminate some noncore portions of the DCCs detected using only 11 μm brightness temperature thresholds, which result in a mean difference of only 0.6 μm for DCC Re estimated from BTD LUTs.

  13. Model simulations with COSMO-SPECS: impact of heterogeneous freezing modes and ice nucleating particle types on ice formation and precipitation in a deep convective cloud

    Directory of Open Access Journals (Sweden)

    K. Diehl

    2018-03-01

    Full Text Available In deep convective clouds, heavy rain is often formed involving the ice phase. Simulations were performed using the 3-D cloud resolving model COSMO-SPECS with detailed spectral microphysics including parameterizations of homogeneous and three heterogeneous freezing modes. The initial conditions were selected to result in a deep convective cloud reaching 14 km of altitude with strong updrafts up to 40 m s−1. At such altitudes with corresponding temperatures below −40 °C the major fraction of liquid drops freezes homogeneously. The goal of the present model simulations was to investigate how additional heterogeneous freezing will affect ice formation and precipitation although its contribution to total ice formation may be rather low. In such a situation small perturbations that do not show significant effects at first sight may trigger cloud microphysical responses. Effects of the following small perturbations were studied: (1 additional ice formation via immersion, contact, and deposition modes in comparison to solely homogeneous freezing, (2 contact and deposition freezing in comparison to immersion freezing, and (3 small fractions of biological ice nucleating particles (INPs in comparison to higher fractions of mineral dust INP. The results indicate that the modification of precipitation proceeds via the formation of larger ice particles, which may be supported by direct freezing of larger drops, the growth of pristine ice particles by riming, and by nucleation of larger drops by collisions with pristine ice particles. In comparison to the reference case with homogeneous freezing only, such small perturbations due to additional heterogeneous freezing rather affect the total precipitation amount. It is more likely that the temporal development and the local distribution of precipitation are affected by such perturbations. This results in a gradual increase in precipitation at early cloud stages instead of a strong increase at

  14. Aerosol Properties and Their Impacts on Surface CCN at the ARM Southern Great Plains Site during the 2011 Midlatitude Continental Convective Clouds Experiment

    Institute of Scientific and Technical Information of China (English)

    Timothy LOGAN; Xiquan DONG; Baike XI

    2018-01-01

    Aerosol particles are of particular importance because of their impacts on cloud development and precipitation processes over land and ocean.Aerosol properties as well as meteorological observations from the Department of Energy Atmospheric Radiation Measurement (ARM) platform situated in the Southern Great Plains (SGP) are utilized in this study to illustrate the dependence of continental cloud condensation nuclei (CCN) number concentration (NCCN) on aerosol type and transport pathways.ARM-SGP observations from the 2011 Midlatitude Continental Convective Clouds Experiment field campaign are presented in this study and compared with our previous work during the 2009-10 Clouds,Aerosol,and Precipitation in the Marine Boundary Layer field campaign over the current ARM Eastern North Atlantic site.Northerly winds over the SGP reflect clean,continental conditions with aerosol scattering coefficient (σsp) values less than 20 Mm-1 and NCCN values less than 100 cm-3.However,southerly winds over the SGP are responsible for the observed moderate to high correlation (R)among aerosol loading (σsp > 60 Mm-1) and NCCN,carbonaceous chemical species (biomass burning smoke),and precipitable water vapor.This suggests a common transport mechanism for smoke aerosols and moisture via the Gulf of Mexico,indicating a strong dependence on air mass type.NASA MERRA-2 reanalysis aerosol and chemical data are moderately to highly correlated with surface ARM-SGP data,suggesting that this facility can represent surface aerosol conditions in the SGP,especially during strong aerosol loading events that transport via the Gulf of Mexico.Future long-term investigations will help to understand the seasonal influences of air masses on aerosol,CCN,and cloud properties over land in comparison to over ocean.

  15. Utilizing CLASIC observations and multiscale models to study the impact of improved Land surface representation on modeling cloud- convection

    Energy Technology Data Exchange (ETDEWEB)

    Niyogi, Devdutta S. [Purdue

    2013-06-07

    The CLASIC experiment was conducted over the US southern great plains (SGP) in June 2007 with an objective to lead an enhanced understanding of the cumulus convection particularly as it relates to land surface conditions. This project was design to help assist with understanding the overall improvement of land atmosphere convection initiation representation of which is important for global and regional models. The study helped address one of the critical documented deficiency in the models central to the ARM objectives for cumulus convection initiation and particularly under summer time conditions. This project was guided by the scientific question building on the CLASIC theme questions: What is the effect of improved land surface representation on the ability of coupled models to simulate cumulus and convection initiation? The focus was on the US Southern Great Plains region. Since the CLASIC period was anomalously wet the strategy has been to use other periods and domains to develop the comparative assessment for the CLASIC data period, and to understand the mechanisms of the anomalous wet conditions on the tropical systems and convection over land. The data periods include the IHOP 2002 field experiment that was over roughly same domain as the CLASIC in the SGP, and some of the DOE funded Ameriflux datasets.

  16. Time-dependent, non-monotonic response of warm convective cloud fields to changes in aerosol loading

    Directory of Open Access Journals (Sweden)

    G. Dagan

    2017-06-01

    Full Text Available Large eddy simulations (LESs with bin microphysics are used here to study cloud fields' sensitivity to changes in aerosol loading and the time evolution of this response. Similarly to the known response of a single cloud, we show that the mean field properties change in a non-monotonic trend, with an optimum aerosol concentration for which the field reaches its maximal water mass or rain yield. This trend is a result of competition between processes that encourage cloud development versus those that suppress it. However, another layer of complexity is added when considering clouds' impact on the field's thermodynamic properties and how this is dependent on aerosol loading. Under polluted conditions, rain is suppressed and the non-precipitating clouds act to increase atmospheric instability. This results in warming of the lower part of the cloudy layer (in which there is net condensation and cooling of the upper part (net evaporation. Evaporation at the upper part of the cloudy layer in the polluted simulations raises humidity at these levels and thus amplifies the development of the next generation of clouds (preconditioning effect. On the other hand, under clean conditions, the precipitating clouds drive net warming of the cloudy layer and net cooling of the sub-cloud layer due to rain evaporation. These two effects act to stabilize the atmospheric boundary layer with time (consumption of the instability. The evolution of the field's thermodynamic properties affects the cloud properties in return, as shown by the migration of the optimal aerosol concentration toward higher values.

  17. Save Maritime Systems Testbed

    Directory of Open Access Journals (Sweden)

    Bolles André

    2014-06-01

    Full Text Available ‘Safe voyage from berth to berth’ — this is the goal of all e-navigation strains, driven by new technologies, new infrastructures and new organizational structures on bridge, on shore as well as in the cloud. To facilitate these efforts suitable engineering and safety/risk assessment methods have to be applied. Understanding maritime transportation as a sociotechnical system allows system engineering methods to be applied. Formal and simulation based verification and validation of e-navigation technologies are important methods to obtain system safety and reliability. The modelling and simulation toolset HAGGIS provides methods for system specification and formal risk analysis. It provides a modelling framework for processes, fault trees and generic hazard specification and a physical world and maritime traffic simulation system. HAGGIS is accompanied by the physical test bed LABSKAUS which implements a reference port and waterway. Additionally, it contains an experimental Vessel Traffic Services (VTS implementation and a mobile integrated bridge enabling in situ experiments for technology evaluation, testing, ground research and demonstration. This paper describes an integrated seamless approach for developing new e-navigation technologies starting with virtual simulation based assessment and ending in physical real world demonstrations.

  18. Impact of Biomass Burning Aerosols on Cloud Formation in Coastal Regions

    Science.gov (United States)

    Nair, U. S.; Wu, Y.; Reid, J. S.

    2017-12-01

    In the tropics, shallow and deep convective cloud structures organize in hierarchy of spatial scales ranging from meso-gamma (2-20 km) to planetary scales (40,000km). At the lower end of the spectrum is shallow convection over the open ocean, whose upscale growth is dependent upon mesoscale convergence triggers. In this context, cloud systems associated with land breezes that propagate long distances into open ocean areas are important. We utilized numerical model simulations to examine the impact of biomass burning on such cloud systems in the maritime continent, specifically along the coastal regions of Sarawak. Numerical model simulations conducted using the Weather Research and Forecasting Chemistry (WRF-Chem) model show spatial patterns of smoke that show good agreement to satellite observations. Analysis of model simulations show that, during daytime the horizontal convective rolls (HCRs) that form over land play an important role in organizing transport of smoke in the coastal regions. Alternating patterns of low and high smoke concentrations that are well correlated to the wavelengths of HCRs are found in both the simulations and satellite observations. During night time, smoke transport is modulated by the land breeze circulation and a band of enhanced smoke concentration is found along the land breeze front. Biomass burning aerosols are ingested by the convective clouds that form along the land breeze and leads to changes in total water path, cloud structure and precipitation formation.

  19. Development of Seasonal BRDF Models to Extend the Use of Deep Convective Clouds as Invariant Targets for Satellite SWIR-Band Calibration

    Directory of Open Access Journals (Sweden)

    Rajendra Bhatt

    2017-10-01

    Full Text Available Tropical deep convective clouds (DCC are an excellent invariant target for vicarious calibration of satellite visible (VIS and near-infrared (NIR solar bands. The DCC technique (DCCT is a statistical approach that collectively analyzes all identified DCC pixels on a monthly basis. The DCC reflectance in VIS and NIR spectrums is mainly a function of cloud optical depth, and provides a stable monthly statistical mode. However, for absorption shortwave infrared (SWIR bands, the monthly DCC response is found to exhibit large seasonal cycles that make the implementation of the DCCT more challenging at these wavelengths. The seasonality assumption was tested using the SNPP-VIIRS SWIR bands, with up to 50% of the monthly DCC response temporal variation removed through deseasonalization. In this article, a monthly DCC bidirectional reflectance distribution function (BRDF approach is proposed, which is found to be comparable to or can outperform the effects of deseasonalization alone. To demonstrate that the SNPP-VIIRS DCC BRDF can be applied to other JPSS VIIRS imagers in the same 13:30 sun-synchronous orbit, the VIIRS DCC BRDF was applied to Aqua-MODIS. The Aqua-MODIS SWIR band DCC reflectance natural variability is reduced by up to 45% after applying the VIIRS-based monthly DCC BRDFs.

  20. 75 FR 5241 - Maritime Communications

    Science.gov (United States)

    2010-02-02

    ...] Maritime Communications AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: In this... that its rules governing the Maritime Radio Services continue to promote maritime safety, maximize effective and efficient use of the spectrum available for maritime communications, accommodate technological...

  1. On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

    Science.gov (United States)

    Gayet, J.-F.; Mioche, G.; Bugliaro, L.; Protat, A.; Minikin, A.; Wirth, M.; Dörnbrack, A.; Shcherbakov, V.; Mayer, B.; Garnier, A.; Gourbeyre, C.

    2012-01-01

    During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/-58 °C). The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C) and nadir looking remote sensing observations (DLR WALES Lidar). Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm-3, 30 km-1 and 0.5 g m-3, respectively) are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC) and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved IWC up to 1 g m-3 may be observed near the cloud top

  2. On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

    Directory of Open Access Journals (Sweden)

    J.-F. Gayet

    2012-01-01

    Full Text Available During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/−58 °C. The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C and nadir looking remote sensing observations (DLR WALES Lidar. Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm−3, 30 km−1 and 0.5 g m−3, respectively are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved

  3. Green Maritime Logistics

    DEFF Research Database (Denmark)

    Psaraftis, Harilaos N.

    2016-01-01

    By green maritime logistics we mean achieving an acceptable environmental performance of the maritime transport logistical supply chain while at the same time respecting traditional economic criteria. In this paper the environmental focus is on maritime emissions. Achieving such goal may involve ...

  4. Ensemble cloud-resolving modelling of a historic back-building mesoscale convective system over Liguria: the San Fruttuoso case of 1915

    Science.gov (United States)

    Parodi, Antonio; Ferraris, Luca; Gallus, William; Maugeri, Maurizio; Molini, Luca; Siccardi, Franco; Boni, Giorgio

    2017-05-01

    Highly localized and persistent back-building mesoscale convective systems represent one of the most dangerous flash-flood-producing storms in the north-western Mediterranean area. Substantial warming of the Mediterranean Sea in recent decades raises concerns over possible increases in frequency or intensity of these types of events as increased atmospheric temperatures generally support increases in water vapour content. However, analyses of the historical record do not provide a univocal answer, but these are likely affected by a lack of detailed observations for older events. In the present study, 20th Century Reanalysis Project initial and boundary condition data in ensemble mode are used to address the feasibility of performing cloud-resolving simulations with 1 km horizontal grid spacing of a historic extreme event that occurred over Liguria: the San Fruttuoso case of 1915. The proposed approach focuses on the ensemble Weather Research and Forecasting (WRF) model runs that show strong convergence over the Ligurian Sea (17 out of 56 members) as these runs are the ones most likely to best simulate the event. It is found that these WRF runs generally do show wind and precipitation fields that are consistent with the occurrence of highly localized and persistent back-building mesoscale convective systems, although precipitation peak amounts are underestimated. Systematic small north-westward position errors with regard to the heaviest rain and strongest convergence areas imply that the reanalysis members may not be adequately representing the amount of cool air over the Po Plain outflowing into the Ligurian Sea through the Apennines gap. Regarding the role of historical data sources, this study shows that in addition to reanalysis products, unconventional data, such as historical meteorological bulletins, newspapers, and even photographs, can be very valuable sources of knowledge in the reconstruction of past extreme events.

  5. On the Link Between Ocean Biota Emissions, Aerosol, and Maritime Clouds: Airborne, Ground, and Satellite Measurements Off the Coast of California

    Science.gov (United States)

    2009-10-14

    Simpson, 1948; Lovelock et al., 1972; Andreae, 1990; Leck et al., 1990). Facchini et al. (2008a) have also shown that biogenic emissions are a...fastigiata, Dimethyl-2- carboxy-ethylsulphonium hydroxide and its salts, J. Chem. Soc., 3, 1591-1597. Charlson, R. J., Lovelock , J. E., Andreae...aerosols for pristine Arctic clouds, Tellus, 57B, 261-268. Lovelock , J. E., Maggs, R. J., and R. A. Rasmussen (1972). Atmospheric dimethyl sulfide and

  6. An Overview of the Lightning - Atmospheric Chemistry Aspects of the Deep Convective Clouds and Chemistry (DC3) Experiment

    Science.gov (United States)

    Pickering, K. E.; Barth, M. C.; Koshak, W.; Bucsela, E. J.; Allen, D. J.; Weinheimer, A.; Ryerson, T.; Huntrieser, H.; Bruning, E.; MacGorman, D.; hide

    2012-01-01

    Some of the major goals of the DC3 experiment are to determine the contribution of lightning to NO(x) in the anvils of observed thunderstorms, examine the relationship of lightning NO(x) production to flash rates and to lightning channel lengths, and estimate the relative production per flash for cloud-to-ground flashes and intracloud flashes. In addition, the effects of lightning NO(x) production on photochemistry downwind of thunderstorms is also being examined. The talk will survey the observation types that were conducted during DC3 relevant to these goals and provide an overview of the analysis and modeling techniques which are being used to achieve them. NO(x) was observed on three research aircraft during DC3 (the NCAR G-V, the NASA DC-8, and the DLR Falcon) in flights through storm anvils in three study regions (NE Colorado, Central Oklahoma to West Texas, and northern Alabama) where lightning mapping arrays (LMAs) and radar coverage were available. Initial comparisons of the aircraft NOx observations in storm anvils relative to flash rates have been conducted, which will be followed with calculations of the flux of NO(x) through the anvils, which when combined with observed flash rates can be used to estimate storm-average lightning NOx production per flash. The WRF-Chem model will be run for cloud-resolved simulations of selected observed storms during DC3. Detailed lightning information from the LMAs (flash rates and flash lengths as a function of time and vertical distributions of flash channel segments) will be input to the model along with assumptions concerning NO(x) production per CG flash and per IC flash. These assumptions will be tested through comparisons with the aircraft NOx data from anvil traverses. A specially designed retrieval method for lightning NO2 column amounts from the OMI instrument on NASA fs Aura satellite has been utilized to estimate NO2 over the region affected by selected DC3 storms. Combined with NO(x) to NO2 ratios from the

  7. Comparison of mean properties of simulated convection in a cloud-resolving model with those produced by cumulus parameterization

    Energy Technology Data Exchange (ETDEWEB)

    Dudhia, J.; Parsons, D.B. [National Center for Atmospheric Research, Boulder, CO (United States)

    1996-04-01

    An Intensive Observation Period (IOP) of the Atmospheric Radiation Measurement (ARM) Program took place at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site from June 16-26, 1993. The National Center for Atmospheric Research (NCAR)/Penn State Mesoscale Model (MM5) has been used to simulate this period on a 60-km domain with 20- and 6.67-km nests centered on Lamont, Oklahoma. Simulations are being run with data assimilation by the nudging technique to incorporate upper-air and surface data from a variety of platforms. The model maintains dynamical consistency between the fields, while the data correct for model biases that may occur during long-term simulations and provide boundary conditions. For the work reported here the Mesoscale Atmospheric Prediction System (MAPS) of the National Ocean and Atmospheric Administration (NOAA) 3-hourly analyses were used to drive the 60-km domain while the inner domains were unforced. A continuous 10-day period was simulated.

  8. Cross-B convection of artificially created, negative-ion clouds and plasma depressions: Low-speed flow

    International Nuclear Information System (INIS)

    Bernhardt, P.A.

    1988-01-01

    A negative-ion, positive-ion plasma produced by the release of an electron attachment chemical into the F region becomes electrically polarized by the collisions with neutrals moving across magnetic field lines. The resulting electric field causes E x B drift of the two ion species and the residual electrons. The cross-field flow of the modified ionosphere is computed using a two-dimensional numerical simulation which includes electron attachment and mutual neutralization chemistry, self-consistent electric fields, and three-species plasma transport. The velocity of the plasma is initially in the direction of the neutral wind because the negative-ion cloud is a Pedersen conductivity enhancement. As the positive and negative ions react, the Pedersen conductivity becomes depressed below the ambient value and the velocity of the plasma reverses direction. A plasma hole remains after the positive and negative ions have mutually neutralized. The E x B gradient drift instability produces irregularities on the upwind edge of the hole. These processes may be observed experimentally with optical and backscatter-radar diagnostics

  9. Airborne observations of cloud properties on HALO during NARVAL

    Science.gov (United States)

    Konow, Heike; Hansen, Akio; Ament, Felix

    2016-04-01

    The representation of cloud and precipitation processes is one of the largest sources of uncertainty in climate and weather predictions. To validate model predictions of convective processes over the Atlantic ocean, usually satellite data are used. However, satellite products provide just a coarse view with poor temporal resolution of convective maritime clouds. Aircraft-based observations offer a more detailed insight due to lower altitude and high sampling rates. The research aircraft HALO (High Altitude Long Range Research Aircraft) is operated by the German Aerospace Center (DLR). With a ceiling of 15 km, and a range of 10,000 km and more than 10 hours it is able to reach remote regions and operate from higher altitudes than most other research aircraft. Thus, it provides the unique opportunity to exploit regions of the atmosphere that cannot be easily accessed otherwise. Measurements conducted on HALO provide more detailed insights than achievable from satellite data. Therefore, this measurement platform bridges the gap between previous airborne measurements and satellites. The payload used for this study consists of, amongst others, a suite of passive microwave radiometers, a cloud radar, and a water vapor DIAL. To investigate cloud and precipitation properties of convective maritime clouds, the NARVAL (Next-generation Aircraft Remote-Sensing for Validation Studies) campaign was conducted in winter 2013/2014 out of Barbados and Keflavik (Iceland). This campaign was one of the first that took place on the HALO aircraft. During the experiment's two parts 15 research flights were conducted (8 flights during NARVAL-South out of Barbados to investigate trade-wind cumuli and 7 flights out of Keflavik with focus on mid-latitude cyclonic systems). Flight durations were between five and nine hours, amounting to roughly 118 flight hours overall. 121 dropsondes were deployed. In fall 2016 two additional aircraft campaigns with the same payload will take place: The

  10. Abbreviations in Maritime English

    Science.gov (United States)

    Yang, Zhirong

    2011-01-01

    Aiming at the phenomena that more and more abbreviations occur in maritime English correspondences, the composing laws of the abbreviations in maritime English correspondence are analyzed, and the correct methods to answer the abbreviations are pointed out, and the translation method of abbreviations are summarized in this article, and the…

  11. Rayleigh convective instability in the presence of phase transitions of water vapor. The formation of large-scale eddies and cloud structures

    International Nuclear Information System (INIS)

    Shmerlin, Boris Ya; Kalashnik, Maksim V

    2013-01-01

    Convective motions in moist saturated air are accompanied by the release of latent heat of condensation. Taking this effect into account, we consider the problem of convective instability of a moist saturated air layer, generalizing the formulation of the classical Rayleigh problem. An analytic solution demonstrating the fundamental difference between moist convection and Rayleigh convection is obtained. Upon losing stability in the two-dimensional case, localized convective rolls or spatially periodic chains of rollers with localized areas of upward motion evolve. In the case of axial symmetry, the growth of localized convective vortices with circulation characteristic of tropical cyclones (hurricanes) is possible at the early stages of development and on the scale of tornados to tropical cyclones. (methodological notes)

  12. Comparison of CloudSat and TRMM radar reflectivities

    Indian Academy of Sciences (India)

    Tropical deep convective clouds drive the large scale circulation of ... information concerning tropical clouds since 1998 ..... and CloudSat Data Processing Center, NASA for providing .... ical precipitating clouds ranging from shallow to deep.

  13. EUROPEAN MARITIME TRANSPORT POLICY

    Directory of Open Access Journals (Sweden)

    Jerzy Kujawa

    2014-03-01

    Full Text Available The article describes the common EU policy on maritime transport, which comprises almost 80% of the volume of external trade of the Union and about 40% of internal transport needs. The first part of the paper presents the origins of the common maritime transport policy and the difficulties encountered during its initial formation. Subsequently, the evolution of the concepts of the policy and its current shape is discussed. The final, substantial part of the article describes the main aims and directions of the EU maritime transport policy and includes an evaluation of the effects of the policy.

  14. The Maritime Engineering Education

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent; Nielsen, Ulrik Dam; Lützen, Marie

    2012-01-01

    This article describes the outcome of a survey initiated by the Danish Maritime Fund (DMF). The survey resulted in a report that describes the engineering competencies requested by the Danish maritime industry. This is of interest since the desired competencies have changed in the past one to two...... decades, where Denmark no longer has a considerable ship-building industry. Furthermore, the DMF initiated report concludes that the demand for maritime engineers in the industry is larger than the output. The report sets forth a series of recommendations to the industry as well as the universities...... to enable meeting the demand for maritime engineers in Denmark. The recommendations are outlined together with the work commenced at the Technical University of Denmark (DTU) and the University of Southern Denmark (SDU) to follow up on the recommendations in the report....

  15. Maritime security report. November 2000 [Commercial maritime drug smuggling

    Science.gov (United States)

    2000-11-01

    Port and security programs being implemented in Colombia's port facilities, maritime jurisdictions, and the marine intermodal shipping cycle are producing successful results against commercial maritime drug smuggling. This security reports examines t...

  16. The Use of the Deep Convective Cloud Technique (DCCT) to Monitor On-Orbit Performance of the Geostationary Lightning Mapper (GLM): Use of Lightning Imaging Sensor (LIS) Data as Proxy

    Science.gov (United States)

    Buechler, Dennis E.; Christian, H. J.; Koshak, William J.; Goodman, Steve J.

    2013-01-01

    The Geostationary Lightning Mapper (GLM) on the next generation Geostationary Operational Environmental Satellite-R (GOES-R) will not have onboard calibration capability to monitor its performance. The Lightning Imaging Sensor (LIS) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite has been providing observations of total lightning over the Earth's Tropics since 1997. The GLM design is based on LIS heritage, making it a good proxy dataset. This study examines the performance of LIS throughout its time in orbit. This was accomplished through application of the Deep Convective Cloud Technique (DCCT) (Doelling et al., 2004) to LIS background pixel radiance data. The DCCT identifies deep convective clouds by their cold Infrared (IR) brightness temperatures and using them as invariant targets in the solar reflective portion of the solar spectrum. The GLM and LIS operate in the near-IR at a wavelength of 777.4 nm. In the present study the IR data is obtained from the Visible Infrared Sensor (VIRS) which is collocated with LIS onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. The DCCT is applied to LIS observations for July and August of each year from 1998-2010. The resulting distributions of LIS background DCC pixel radiance for each July August are very similar, indicating stable performance. The mean radiance of the DCCT analysis does not show a long term trend and the maximum deviation of the July August mean radiance for each year is within 0.7% of the overall mean. These results demonstrate that there has been no discernible change in LIS performance throughout its lifetime. A similar approach will used for monitoring the performance of GLM, with cold clouds identified using IR data from the Advanced Baseline Imager (ABI) which will also be located on GOES-R. Since GLM is based on LIS design heritage, the LIS results indicate that GLM should also experience stable performance over its lifetime.

  17. Characteristics of the oceanic MCC, continental MCC, and coastal MCC over the Indonesian maritime continent

    Science.gov (United States)

    Trismidianto

    2018-05-01

    This study explains the comparison of mesoscale convective complexes (MCC) characteristics in the oceans, land and in the coast over Indonesian maritime continent (IMC). MCCs were identified and tracked during 15-years (2001-2015) over IMC by infrared satellite imagery using an algorithm that combines criteria of cloud coverage, eccentricity, and cloud lifetime. Infrared satellite imagery was obtained from Himawari generation satellite data. This study showed most of the continental MCC found near the mountains and the high elevation areas. The frequency of MCC occurrences was larger over the land than over the ocean. The oceanic MCCs, which lasted for more than 12 hours, were longer-lived than the continental MCCs. The MCCs with small size most frequently occurred in the continent, in contrast, the MCC with the medium and large size were most concentrated over the ocean. Generally, the continental and coastal MCC initiation occurs in the late afternoon and reach maximum size around midnight before decaying the next morning. In contrast, the oceanic MCC dominantly develops in midnight, and reach maximum size in the morning and then MCC decayed and dissipated from noon until afternoon. The evolution of MCC development in the ocean, land, and in the coast has almost the same stages and ways.

  18. Cloud-Top Entrainment in Stratocumulus Clouds

    Science.gov (United States)

    Mellado, Juan Pedro

    2017-01-01

    Cloud entrainment, the mixing between cloudy and clear air at the boundary of clouds, constitutes one paradigm for the relevance of small scales in the Earth system: By regulating cloud lifetimes, meter- and submeter-scale processes at cloud boundaries can influence planetary-scale properties. Understanding cloud entrainment is difficult given the complexity and diversity of the associated phenomena, which include turbulence entrainment within a stratified medium, convective instabilities driven by radiative and evaporative cooling, shear instabilities, and cloud microphysics. Obtaining accurate data at the required small scales is also challenging, for both simulations and measurements. During the past few decades, however, high-resolution simulations and measurements have greatly advanced our understanding of the main mechanisms controlling cloud entrainment. This article reviews some of these advances, focusing on stratocumulus clouds, and indicates remaining challenges.

  19. China's Maritime Strategy Peaceful Rise

    National Research Council Canada - National Science Library

    Horrell, Steven L

    2008-01-01

    .... As a result the global maritime environment will be key to this continental power's continued growth As a subset of maritime strategy China's naval strategy and accompanying People's Liberation Army...

  20. Maritime Cyber Security University Research

    Science.gov (United States)

    2016-05-01

    i Classification | CG-926 RDC | author | audience | month year Maritime Cyber Security University Research Phase I - Final Report...Distribution Statement A: Approved for public release; distribution is unlimited. May 2016 Report No. CG-D-06-16 Maritime Cyber Security...Director United States Coast Guard Research & Development Center 1 Chelsea Street New London, CT 06320 Maritime Cyber Security University

  1. 75 FR 10692 - Maritime Communications

    Science.gov (United States)

    2010-03-09

    ...] Maritime Communications ACTION: Final rule; correction. SUMMARY: The Federal Communications Commission published in the Federal Register of February 2, 2010 (75 FR 5241), a document in the Maritime Radio..., 2010 (75 FR 5241) to ensure that its rules governing the Maritime Radio Services continue to promote...

  2. A transilient matrix for moist convection

    Energy Technology Data Exchange (ETDEWEB)

    Romps, D.; Kuang, Z.

    2011-08-15

    A method is introduced for diagnosing a transilient matrix for moist convection. This transilient matrix quantifies the nonlocal transport of air by convective eddies: for every height z, it gives the distribution of starting heights z{prime} for the eddies that arrive at z. In a cloud-resolving simulation of deep convection, the transilient matrix shows that two-thirds of the subcloud air convecting into the free troposphere originates from within 100 m of the surface. This finding clarifies which initial height to use when calculating convective available potential energy from soundings of the tropical troposphere.

  3. Marine and maritime uses

    Science.gov (United States)

    1975-01-01

    Activities related to: (1) understanding, controlling, and using the ocean's biological and physical processes for food and energy production and ship design purposes, and (2) providing navigation, communication, and data transmission technological aids which improve efficiency and enhance safety in maritime operations are disclosed.

  4. Power in the Maritimes

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    This article highlights generation and transmission developments in Atlantic Canada, up-dates current projects and future planning, and features authoritative statements by utility executives about the energy situation in the Maritime provinces. Some details of the Point Lepreau 630 MW CANDU reactor are given. (N.D.H.)

  5. 简述海事部门云计算平台建设的意义及研究方法%A Brief Introduction on the Significance of the Establishment of the Cloud Computing Platform and Its Research Method in Maritime Department

    Institute of Scientific and Technical Information of China (English)

    周章海

    2015-01-01

    This paper discussed the current situations of the information resources processing and pointed out the objectives and significance to build a cloud computing platform in the maritime depart-ment.It also determined the research method of the platform and through this managers could integrate the existing information resources and do a thorough cleaning,filtering and aggregation of the business data to ultimately realize the unified management of applications and business data of all national mari-time departments.%本文阐述了当前海事部门信息资源处理的现状,指明了海事部门搭建云计算平台的目标与意义,确定了海事部门云计算平台建设的研究方法,通过统一云平台,实现对现有信息化资源的整合,对业务流程的梳理,对业务数据的统一清洗、筛选和聚合,最终达到对全国海事部门应用系统和业务数据的统一管理。

  6. Precursory strong-signal characteristics of the convective clouds of the Central Tibetan Plateau detected by radar echoes with respect to the evolutionary processes of an eastward-moving heavy rainstorm belt in the Yangtze River Basin

    Science.gov (United States)

    Zhao, Yang; Xu, Xiangde; Ruan, Zheng; Chen, Bin; Wang, Fang

    2018-03-01

    The integrated analysis of the data from a C-band frequency-modulated continuous-wave (C-FMCW) radar site in Naqu obtained during a rainstorm over the middle and lower reaches of the Yangtze River and the data concerning the three-dimensional structure of the circulation of the precipitation system that occurred over the lower reaches of the Yangtze River Basin during the Third Tibetan Plateau (TP) Atmospheric Experiment from August 15th to 19th, 2014, was carried out. The changes in the echo intensity at the C-FMCW radar site in Naqu were of regional indicative significance for the characteristics of the whole-layer apparent heat source Q1 in local areas and the region of the adjacent river source area, including the Yangtze River, Yellow River, and Lancang River (hereinafter referred to as the "source area of three rivers"), as well as to the vertical speeds due to the development of convection. This study indicates that the C-FMCW radar echo intensity of the plateau convection zone and the related power structures of the coupled dipole circulations in the middle layer of the atmosphere, as well as in the upper atmospheric level divergence and lower atmospheric level convergence, are important stimuli for convective clouds in this region. Furthermore, these radar data provided a physical image of the development and maintenance mechanisms of an eastward-moving heavy rainstorm belt. This study also shows that changes in the echo intensities at the C-FMCW radar site of Naqu can provide strong signals related to heavy rainstorm processes in the upper reaches of the Yangtze River.

  7. Identifying Maritime Logistics Competences for Sustaining Maritime Economies

    DEFF Research Database (Denmark)

    Gammelgaard, Britta; Kinra, Aseem; Sornn-Friese, Henrik

    This paper conducts a comparative assessment of the Danish maritime cluster, measured against a range of international known and respected maritime clusters like Virginia, London, the Netherlands, Singapore, Shanghai, Norway and Hong Kong. The aim is also to bring out the characteristics of the D......This paper conducts a comparative assessment of the Danish maritime cluster, measured against a range of international known and respected maritime clusters like Virginia, London, the Netherlands, Singapore, Shanghai, Norway and Hong Kong. The aim is also to bring out the characteristics...... of the Danish maritime cluster’s development, and unique competences. The comparative assessment highlights the importance of different historical and geographical backgrounds, when explaining the relative positions of the Danish, and other comparable maritime clusters. Other specific common features...

  8. Convective sources of trajectories traversing the tropical tropopause layer

    Directory of Open Access Journals (Sweden)

    A.-S. Tissier

    2016-03-01

    Full Text Available Transit properties across the tropical tropopause layer are studied using extensive forward and backward Lagrangian diabatic trajectories between cloud tops and the reference surface 380 K. After dividing the tropical domain into 11 subregions according to the distribution of land and convection, we estimate the contribution of each region to the upward mass flux across the 380 K surface and to the vertical distribution of convective sources and transit times over the period 2005–2008. The good agreement between forward and backward statistics is the basis of the results presented here. It is found that about 85 % of the tropical parcels at 380 K originate from convective sources throughout the year. From November to April, the sources are dominated by the warm pool which accounts for up to 70 % of the upward flux. During boreal summer, the Asian monsoon region is the largest contributor with similar contributions from the maritime and continental parts of the region; however, the vertical distributions and transit times associated with these two subregions are very different. Convective sources are generally higher over the continental part of the Asian monsoon region, with shorter transit times. We estimate the monthly averaged upward mass flux on the 380 K surface and show that the contribution from convective outflow accounts for 80 % on average and explains most of its seasonal variations. The largest contributor to the convective flux is the South Asian Pacific region (warm pool at 39 % throughout the year followed by oceanic regions surrounding continental Asia at 18 % and Africa at 10.8 %. Continental Asian lowlands account for 8 %. The Tibetan Plateau is a minor overall contributor (0.8 %, but transport from convective sources in this region is very efficient due to its central location beneath the Asian upper level anticyclone. The core results are robust to uncertainties in data and methods, but the vertical source

  9. A study of the 21 March 2012 tornadic quasi linear convective system in Catalonia

    Science.gov (United States)

    Bech, Joan; Arús, Joan; Castán, Salvador; Pineda, Nicolau; Rigo, Tomeu; Montanyà, Joan; van der Velde, Oscar

    2015-05-01

    This study presents a description of a quasi linear convective system that took place in Catalonia (NE Spain) on 21 March 2012 producing heavy rainfall, moderate lightning activity and a weak tornado in the village of Ivars d'Urgell around 19 UTC after local sunset. A post-event survey indicated EF0 and EF1 damage in houses of the village - roofs and ceilings, broken windows, fences and walls and trees knocked down - along a track approximately 4 km long and about 20 m wide. Doppler radar observations show that the parent thunderstorm that spawned the tornado was one of a series that developed along a convective line that moved from S to N, initiating convective activity in terms of precipitation and lightning in the Mediterranean Sea and moving inland in S Catalonia (Tarragona and Salou coastal areas, producing local flash floods). Convective activity remained several hours with series of thunderstorms developing along the same paths. The synoptic situation was dominated by a high pressure ridge extending from northern Africa to central Europe, with a closed maximum sea level pressure area around 1036 hPa over northern France, southern Germany and Austria. On the other hand a relative low pressure area seen on 850 hPa and upper levels was present over the Iberian Peninsula, favouring a southern maritime flow from the Mediterranean between the forward part of the low pressure area and the high pressure system which blocked the advance of the low to the east. In the study we examine both the synoptic environment and storm scale observations with Doppler radar and total lightning data (cloud to ground and intracloud flashes) that lead to this cool-season severe convective event which is remarkable given the fact that, unlike in this case, most reported tornadoes in the region occur during the warm season (with peaks in August and September) and during daylight hours (6 to 18 UTC).

  10. Maritime English for Communication and Cooperation.

    Science.gov (United States)

    Thiel, Teresa A.

    Because most maritime accidents are caused by human error, notably breakdowns in communication or cooperation, and because English is the international maritime language, instruction in maritime English for communication and cooperation is an important element in maritime education. The International Maritime Organization, a specialized agency of…

  11. Green Maritime Logistics

    DEFF Research Database (Denmark)

    Psaraftis, Harilaos N.

    2014-01-01

    Typical problems in maritime logistics include, among others, optimal ship speed, ship routing and scheduling, fleet deployment, fleet size and mix, weather routing, intermodal network design, modal split, transshipment, queuing at ports, terminal management, berth allocation, and total supply...... chain management. The traditional analysis of these problems has been in terms of cost- benefit and other optimization criteria from the point of view of the logistics provider, carrier, shipper, or other end-user. Such traditional analysis by and large either ignores environmental issues, or considers...... them of secondary importance. Green maritime logistics tries to bring the environmental dimension into the problem, and specifically the dimension of emissions reduction, by analyzing various trade-offs and exploring ‘win-win’ solutions. This talk takes a look at the trade-offs that are at stake...

  12. Det Maritime Hus

    DEFF Research Database (Denmark)

    Albrechtsen, Thomas Rohde Skovdal

    2017-01-01

    Denne rapport er en slutevaluering af udviklingsprojektet Det Maritime Hus, og består af en analyse og diskussion af en spørgeskemaundersøgelse foretaget i perioden efterår 2014 til forår 2017. Evalueringen besvarer følgende tre spørgsmål og målsætninger med projektet: 1. På hvilke måder formåede...... lærere undervisningsforløbet som brugbart i forhold til egen undervisning? Konklusionen på evalueringen er, at Det Maritime Hus har formået at understøtte de deltagende elevers interesse og læring inden for science-området gennem de designede undervisningsforløb, som er blevet udbudt og gennemført i...

  13. Occupational asthma in maritime environments

    DEFF Research Database (Denmark)

    Lucas, David; Loddé, Brice; Jepsen, Jørgen Riis

    2016-01-01

    In 2006 we published our first review based on the available literature on occupational asthma in maritime environments in the “International Maritime Health” journal. Since then, we have obtained a great deal of new knowledge on asthma in seafood workers and fishermen and on the impact...... of exposures from sulphites preservatives, container fumigants etc. in maritime workers. This review aims to provide an update of the current knowledge base about occupational asthma in a maritime context and to provide recommendations regarding medical surveillance of workers at risk....

  14. Covariability in the Monthly Mean Convective and Radiative Diurnal Cycles in the Amazon

    Science.gov (United States)

    Dodson, Jason B.; Taylor, Patrick C.

    2015-01-01

    The diurnal cycle of convective clouds greatly influences the radiative energy balance in convectively active regions of Earth, through both direct presence, and the production of anvil and stratiform clouds. Previous studies show that the frequency and properties of convective clouds can vary on monthly timescales as a result of variability in the monthly mean atmospheric state. Furthermore, the radiative budget in convectively active regions also varies by up to 7 Wm-2 in convectively active regions. These facts suggest that convective clouds connect atmospheric state variability and radiation variability beyond clear sky effects alone. Previous research has identified monthly covariability between the diurnal cycle of CERES-observed top-of-atmosphere radiative fluxes and multiple atmospheric state variables from reanalysis over the Amazon region. ASVs that enhance (reduce) deep convection, such as CAPE (LTS), tend to shift the daily OLR and cloud albedo maxima earlier (later) in the day by 2-3 hr. We first test the analysis method using multiple reanalysis products for both the dry and wet seasons to further investigate the robustness of the preliminary results. We then use CloudSat data as an independent cloud observing system to further evaluate the relationships of cloud properties to variability in radiation and atmospheric states. While CERES can decompose OLR variability into clear sky and cloud effects, it cannot determine what variability in cloud properties lead to variability in the radiative cloud effects. Cloud frequency, cloud top height, and cloud microphysics all contribute to the cloud radiative effect, all of which are observable by CloudSat. In addition, CloudSat can also observe the presence and variability of deep convective cores responsible for the production of anvil clouds. We use these capabilities to determine the covariability of convective cloud properties and the radiative diurnal cycle.

  15. Center for Maritime Safety and Health Studies

    Data.gov (United States)

    Federal Laboratory Consortium — Established in November 2015, the Center for Maritime Safety and Health Studies (CMSHS) promotes safety and health for all maritime workers, including those employed...

  16. Hybrid Maritime Warfare

    DEFF Research Database (Denmark)

    Schaub Jr, Gary John; Murphy, Martin; Hoffman, Frank

    2017-01-01

    Russia’s use of hybrid warfare techniques has raised concerns about the security of the Baltic States. Gary Schaub, Jr, Martin Murphy and Frank G Hoffman recommend a series of measures to augment NATO’s Readiness Action Plan in the Baltic region, including increasing the breadth and depth of naval...... exercises, and improving maritime domain awareness through cooperative programmes. They also suggest unilateral and cooperative measures to develop a sound strategic communications strategy to counter Moscow’s information operations, reduce dependence on Russian energy supplies and build the resilience...

  17. Digitization in Maritime Industry

    DEFF Research Database (Denmark)

    Constantiou, Ioanna; Shollo, Arisa; Kreiner, Kristian

    2017-01-01

    Digitization in the maritime industry is expected to transform businesses. The recently introduced mobile technologies in inter-organizational processes is an example of digitization in an industry which moves very slowly towards digital transformation. We focus on the influence of mobile...... technologies on control practices in inter-organizational processes related to coping with an engine failure. We collected qualitative data from in depth interviews with representatives of the involved parties. We identify organizational and behavioural challenges hindering information sharing during problem...... technologies increase information sharing and thus the efficiency of inter-organizational processes when coping with an engine failure....

  18. INTERNET COMMERCE IN MARITIME INDUSTRY

    Directory of Open Access Journals (Sweden)

    Monika Szyda

    2014-06-01

    Full Text Available Internet commerce in Poland is growing rapidly, entering into new industries and of-fering a wider and wider range of goods and services. For electronic commerce is open maritime industry, as evidenced by the maritime e-commerce. This aspect of e-commerce is not a popular topic of publications and research. In this article the author presents the genesis of electronic commerce in the maritime industry taking into account the particular business relationship business-to-business (B2B. Then attempt to characterize maritime e-commerce in business-to-customer (B2C relationship. The purpose of this article is to identify the attributes of internet commerce in the maritime industry, having particular re-gard to Polish online market, especially retail.

  19. Evaluation of stratocumulus cloud prediction in the Met Office forecast model during VOCALS-REx

    Directory of Open Access Journals (Sweden)

    S. J. Abel

    2010-11-01

    Full Text Available Observations in the subtropical southeast Pacific obtained during the VOCALS-REx field experiment are used to evaluate the representation of stratocumulus cloud in the Met Office forecast model and to identify key areas where model biases exist. Marked variations in the large scale structure of the cloud field were observed during the experiment on both day-to-day and on diurnal timescales. In the remote maritime region the model is shown to have a good representation of synoptically induced variability in both cloud cover and marine boundary layer depth. Satellite observations show a strong diurnal cycle in cloud fraction and liquid water path in the stratocumulus with enhanced clearances of the cloud deck along the Chilean and Peruvian coasts on certain days. The model accurately simulates the phase of the diurnal cycle but is unable to capture the coastal clearing of cloud. Observations along the 20° S latitude line show a gradual increase in the depth of the boundary layer away from the coast. This trend is well captured by the model (typical low bias of 200 m although significant errors exist at the coast where the model marine boundary layer is too shallow and moist. Drizzle in the model responds to changes in liquid water path in a manner that is consistent with previous ship-borne observations in the region although the intensity of this drizzle is likely to be too high, particularly in the more polluted coastal region where higher cloud droplet number concentrations are typical. Another mode of variability in the cloud field that the model is unable to capture are regions of pockets of open cellular convection embedded in the overcast stratocumulus deck and an example of such a feature that was sampled during VOCALS-REx is shown.

  20. Heat Convection

    Science.gov (United States)

    Jiji, Latif M.

    Professor Jiji's broad teaching experience lead him to select the topics for this book to provide a firm foundation for convection heat transfer with emphasis on fundamentals, physical phenomena, and mathematical modelling of a wide range of engineering applications. Reflecting recent developments, this textbook is the first to include an introduction to the challenging topic of microchannels. The strong pedagogic potential of Heat Convection is enhanced by the follow ing ancillary materials: (1) Power Point lectures, (2) Problem Solutions, (3) Homework Facilitator, and, (4) Summary of Sections and Chapters.

  1. Maritimes and northeast pipeline update

    International Nuclear Information System (INIS)

    Langan, P.

    1998-01-01

    Efforts made by Maritimes and Northeast Pipelines to bring the benefits of natural gas to the Maritime's economy was discussed. Some background on the developments that have brought the company to where they are today and an update on all their activities were presented. These activities and operations are expected to impact and affect the region's economy in a positive way. Particular attention was paid to the company's policy on laterals and the positive effects of that policy on the development of natural gas service and future natural gas distribution business in the Maritimes

  2. INTERNET COMMERCE IN MARITIME INDUSTRY

    OpenAIRE

    Monika Szyda

    2014-01-01

    Internet commerce in Poland is growing rapidly, entering into new industries and of-fering a wider and wider range of goods and services. For electronic commerce is open maritime industry, as evidenced by the maritime e-commerce. This aspect of e-commerce is not a popular topic of publications and research. In this article the author presents the genesis of electronic commerce in the maritime industry taking into account the particular business relationship business-to-business (B2B). Then at...

  3. What favors convective aggregation and why?

    Science.gov (United States)

    Muller, Caroline; Bony, Sandrine

    2015-07-01

    The organization of convection is ubiquitous, but its physical understanding remains limited. One particular type of organization is the spatial self-aggregation of convection, taking the form of cloud clusters, or tropical cyclones in the presence of rotation. We show that several physical processes can give rise to self-aggregation and highlight the key features responsible for it, using idealized simulations. Longwave radiative feedbacks yield a "radiative aggregation." In that case, sufficient spatial variability of radiative cooling rates yields a low-level circulation, which induces the upgradient energy transport and radiative-convective instability. Not only do vertically integrated radiative budgets matter but the vertical profile of cooling is also crucial. Convective aggregation is facilitated when downdrafts below clouds are weak ("moisture-memory aggregation"), and this is sufficient to trigger aggregation in the absence of longwave radiative feedbacks. These results shed some light on the sensitivity of self-aggregation to various parameters, including resolution or domain size.

  4. The Maritime Infrastructure Recovery Plan for the National Strategy for Maritime Security

    National Research Council Canada - National Science Library

    2006-01-01

    ... to the jurisdiction of the United States. The MIRP, the Maritime Commerce Security Plan, and the Maritime Transportation System Security Plan were developed in close coordination under the National Strategy for Maritime Security (NSMS...

  5. Networking the Global Maritime Partnership

    National Research Council Canada - National Science Library

    Galdorisi, George; Hszieh, Stephanie; McKearney, Terry

    2008-01-01

    The modern-day notion of a "Global Maritime Partnership," first introduced by then-CNO Admiral Michael Mullen at the 2005 International Seapower Symposium as "The 1000-Ship Navy," and later enshrined in the new U.S...

  6. MARITIME VIOLENCE : IMPLICATIONS TO MALAYSIA

    Directory of Open Access Journals (Sweden)

    Nurulizwan Ahmad Zubir

    2014-04-01

    Full Text Available Abstract Maritime Piracy has been a serious threat to the international community especially in the SoutheastAsia region. This threat has caused tremendous implications towards the world economy, environment,political stability of the nations involved because 45% of the shipping company passes through theSoutheast Asia. The worrying fact is that these attacks were committed by terrorists as well as traditionalmaritime pirates. This paper examines on the implications of maritime crime in Malaysia and discusseswhether the definition of piracy under the International Law could be applied to these attacks. Thispaper concludes that cooperation between the region’s states and the enhancement of a good securitysystem of one state are needed to combat maritime violence. Thus it is imperative that the internationallaw need to be changed in order to enhance the meaning of piracy and also to include sea terrorism. Key words: piracy, maritime, terrorist

  7. Original deep convection in the atmosphere of Mars driven by the radiative impact of dust and water-ice particles

    Science.gov (United States)

    Spiga, A.; Madeleine, J. B.; Hinson, D.; Millour, E.; Forget, F.; Navarro, T.; Määttänen, A.; Montmessin, F.

    2017-09-01

    We unveil two examples of deep convection on Mars - in dust storms and water-ice clouds - to demonstrate that the radiative effect of aerosols and clouds can lead to powerful convective motions just as much as the release of latent heat in moist convection

  8. Texture orientation-based algorithm for detecting infrared maritime targets.

    Science.gov (United States)

    Wang, Bin; Dong, Lili; Zhao, Ming; Wu, Houde; Xu, Wenhai

    2015-05-20

    Infrared maritime target detection is a key technology for maritime target searching systems. However, in infrared maritime images (IMIs) taken under complicated sea conditions, background clutters, such as ocean waves, clouds or sea fog, usually have high intensity that can easily overwhelm the brightness of real targets, which is difficult for traditional target detection algorithms to deal with. To mitigate this problem, this paper proposes a novel target detection algorithm based on texture orientation. This algorithm first extracts suspected targets by analyzing the intersubband correlation between horizontal and vertical wavelet subbands of the original IMI on the first scale. Then the self-adaptive wavelet threshold denoising and local singularity analysis of the original IMI is combined to remove false alarms further. Experiments show that compared with traditional algorithms, this algorithm can suppress background clutter much better and realize better single-frame detection for infrared maritime targets. Besides, in order to guarantee accurate target extraction further, the pipeline-filtering algorithm is adopted to eliminate residual false alarms. The high practical value and applicability of this proposed strategy is backed strongly by experimental data acquired under different environmental conditions.

  9. Current Issues in Maritime Health

    DEFF Research Database (Denmark)

    Wagtmann, Maria Anne

    2008-01-01

     In the early part of 2008, Maria Anne Wagtmann had the opportunity to interview the former president of the International Maritime Health Association, Dr. Tim Carter, in London about a number of current maritime health issues. In this interview, Dr. Tim Carter, who is cur­rently employed...... as the Chief Medical Advisor for the British government's Department for Transport, gives his personal - and thus non-official - opinions on these issues....

  10. Maritime Violence : Implications to Malaysia

    OpenAIRE

    Zubir, Nurulizwan Ahmad

    2012-01-01

    Abstract Maritime Piracy has been a serious threat to the international community especially in the SoutheastAsia region. This threat has caused tremendous implications towards the world economy, environment,political stability of the nations involved because 45% of the shipping company passes through theSoutheast Asia. The worrying fact is that these attacks were committed by terrorists as well as traditionalmaritime pirates. This paper examines on the implications of maritime crime in M...

  11. Fluctuations in a quasi-stationary shallow cumulus cloud ensemble

    Directory of Open Access Journals (Sweden)

    M. Sakradzija

    2015-01-01

    Full Text Available We propose an approach to stochastic parameterisation of shallow cumulus clouds to represent the convective variability and its dependence on the model resolution. To collect information about the individual cloud lifecycles and the cloud ensemble as a whole, we employ a large eddy simulation (LES model and a cloud tracking algorithm, followed by conditional sampling of clouds at the cloud-base level. In the case of a shallow cumulus ensemble, the cloud-base mass flux distribution is bimodal, due to the different shallow cloud subtypes, active and passive clouds. Each distribution mode can be approximated using a Weibull distribution, which is a generalisation of exponential distribution by accounting for the change in distribution shape due to the diversity of cloud lifecycles. The exponential distribution of cloud mass flux previously suggested for deep convection parameterisation is a special case of the Weibull distribution, which opens a way towards unification of the statistical convective ensemble formalism of shallow and deep cumulus clouds. Based on the empirical and theoretical findings, a stochastic model has been developed to simulate a shallow convective cloud ensemble. It is formulated as a compound random process, with the number of convective elements drawn from a Poisson distribution, and the cloud mass flux sampled from a mixed Weibull distribution. Convective memory is accounted for through the explicit cloud lifecycles, making the model formulation consistent with the choice of the Weibull cloud mass flux distribution function. The memory of individual shallow clouds is required to capture the correct convective variability. The resulting distribution of the subgrid convective states in the considered shallow cumulus case is scale-adaptive – the smaller the grid size, the broader the distribution.

  12. Radiative-convective equilibrium model intercomparison project

    Science.gov (United States)

    Wing, Allison A.; Reed, Kevin A.; Satoh, Masaki; Stevens, Bjorn; Bony, Sandrine; Ohno, Tomoki

    2018-03-01

    RCEMIP, an intercomparison of multiple types of models configured in radiative-convective equilibrium (RCE), is proposed. RCE is an idealization of the climate system in which there is a balance between radiative cooling of the atmosphere and heating by convection. The scientific objectives of RCEMIP are three-fold. First, clouds and climate sensitivity will be investigated in the RCE setting. This includes determining how cloud fraction changes with warming and the role of self-aggregation of convection in climate sensitivity. Second, RCEMIP will quantify the dependence of the degree of convective aggregation and tropical circulation regimes on temperature. Finally, by providing a common baseline, RCEMIP will allow the robustness of the RCE state across the spectrum of models to be assessed, which is essential for interpreting the results found regarding clouds, climate sensitivity, and aggregation, and more generally, determining which features of tropical climate a RCE framework is useful for. A novel aspect and major advantage of RCEMIP is the accessibility of the RCE framework to a variety of models, including cloud-resolving models, general circulation models, global cloud-resolving models, single-column models, and large-eddy simulation models.

  13. Maritime Work and Communication

    Directory of Open Access Journals (Sweden)

    Peter Andersen

    2001-05-01

    Full Text Available This paper presents findings from the project "Elastic Systems" under the Danish Center for Human Machine Interaction. The project aims at developing methods for analyzing dynamic maritime work processes and for designing flexible instrument interfaces that will support changing work environments. Here I only address the former issue, the design issues being published elsewhere, e.g. in Andersen(1999 and Andersen & May (2001. More data can be found in Andersen(2000. The purpose of the present paper is twofold: (1 to present characteristics of maritime work and communication, and (2 to suggest a conceptual framework that covers communicative as well as non-communicative acts. The latter purpose is motivated in two ways. Theoretical motivation: we know that language is self-referential, so that it can speak of non-linguistic entities like ships and waves as well as its own properties, such as the correct wording or style. The easiest way to accomplish this is for language to treat both domains in a similar way. The other motivation is more practical: it is a fact that communication and physical actions are interwoven in maritime work, and a theory that builds on a sharp distinction between these two kinds of behaviors will miss this basic characteristic. The data is from a voyage aboard Sally Maersk from Algeciras to Goteborg and back to Rotterdam. We recorded 60 hours of high quality video, and the paper builds upon a 16 hours trip from Felixstowe to Rotterdam, supplemented by data from simulated voyages in the simulator at the Danish Maritime Institute. The conceptual framework is based on Lind 1994 and Lind 2000 and distinguishes between the following types of action types: (1 Prevent(suppress, avoid: if I hadn't done it, then an undesirable state would have developed. Prevent drifting by using auxiliary rudder. (2 Maintain: if I hadn't done it, then a desirable state would have disappeared. Maintain course. (3 Help: a positive state would have

  14. Using naive Bayes classifier for classification of convective rainfall ...

    Indian Academy of Sciences (India)

    the rainfall intensity in the convective clouds is evaluated using weather radar over the northern Algeria. The results indicate an ... tropical and extratropical regions, are dominated .... MSG is a new series of European geostationary satellites ...

  15. The effect of water solubles on Kelvin effects of the Maritime Polluted ...

    African Journals Online (AJOL)

    In this work microphysical properties of Maritime Polluted aerosols wereextracted from Optical Properties of Aerosols and Clouds (OPAC) after varying the concentrations of water soluble at five different levels. The analytical expressions for the changes in the equilibrium relative humidity (RH), effective radii, effective ...

  16. On the existence of tropical anvil clouds

    Science.gov (United States)

    Seeley, J.; Jeevanjee, N.; Langhans, W.; Romps, D.

    2017-12-01

    In the deep tropics, extensive anvil clouds produce a peak in cloud cover below the tropopause. The dominant paradigm for cloud cover attributes this anvil peak to a layer of enhanced mass convergence in the clear-sky upper-troposphere, which is presumed to force frequent detrainment of convective anvils. However, cloud cover also depends on the lifetime of cloudy air after it detrains, which raises the possibility that anvil clouds may be the signature of slow cloud decay rather than enhanced detrainment. Here we measure the cloud decay timescale in cloud-resolving simulations, and find that cloudy updrafts that detrain in the upper troposphere take much longer to dissipate than their shallower counterparts. We show that cloud lifetimes are long in the upper troposphere because the saturation specific humidity becomes orders of magnitude smaller than the typical condensed water loading of cloudy updrafts. This causes evaporative cloud decay to act extremely slowly, thereby prolonging cloud lifetimes in the upper troposphere. As a consequence, extensive anvil clouds still occur in a convecting atmosphere that is forced to have no preferential clear-sky convergence layer. On the other hand, when cloud lifetimes are fixed at a characteristic lower-tropospheric value, extensive anvil clouds do not form. Our results support a revised understanding of tropical anvil clouds, which attributes their existence to the microphysics of slow cloud decay rather than a peak in clear-sky convergence.

  17. Supporting the Maritime Information Dominance: Optimizing Tactical Network for Biometric Data Sharing in Maritime Interdiction Operations

    Science.gov (United States)

    2015-03-01

    biometric data collection. Capture role- player mock biometric data including finger prints, iris scans, and facial recognition photos. (MOC training...MARITIME INFORMATION DOMINANCE: OPTIMIZING TACTICAL NETWORK FOR BIOMETRIC DATA SHARING IN MARITIME INTERDICTION OPERATIONS by Adam R. Sinsel...MARITIME INFORMATION DOMINANCE: OPTIMIZING TACTICAL NETWORK FOR BIOMETRIC DATA SHARING IN MARITIME INTERDICTION OPERATIONS 6. AUTHOR(S) Adam R

  18. Developing a Model on Improving Maritime English Training for Maritime Transportation Safety

    Science.gov (United States)

    Yercan, Funda; Fricke, Donna; Stone, Laurie

    2005-01-01

    Maritime services form an integral part of what regulatory agencies requires for the safe navigation and operation of vessels. Therefore, the maritime industry's compliance with governmental regulations and international protocols has been essential for maritime safety management. As a basis to this aspect, the preparation of maritime students as…

  19. Maritime archaeology and shipwrecks off Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Tripati, S.; Gaur, A; Sundaresh

    In recent years, maritime archaeological studies have unearthed several of our lost cultural heritages. Many believe that maritime archaeology is a complex and specialized field. Author has penned down his personal experiences in the form...

  20. Neotectonics in the maritime provinces

    International Nuclear Information System (INIS)

    Martin, G.L.

    1988-03-01

    Seismic risk assessment in the Maritime Provinces requires input from not just historical, but also geological sources. A detailed search through published and unpublished geological literature reveals many examples - some probable, some possible -of neotectonic movement in the area. Examples range in tectonic significance from those that reflect exaggerated local imbalance to those that signify deep-seated stress. Evidence for neotectonism in the Maritimes is multidisciplined. It includes deformation in bedrock and quaternary deposits, and regional warping. Recent movement also is indicated by changes in relative sea level, in situ stress fields and geodetic fluctuations. Finally, and most unequivocally, neotectonism in the Maritime Provinces is manifested as the seismic events that have sporadically affected the area throughout its recent geological history, and continue up to the present day. 288 refs

  1. Maritime wideband communication networks video transmission scheduling

    CERN Document Server

    Yang, Tingting

    2014-01-01

    This Springer Brief covers emerging maritime wideband communication networks and how they facilitate applications such as maritime distress, urgency, safety and general communications. It provides valuable insight on the data transmission scheduling and protocol design for the maritime wideband network. This brief begins with an introduction to maritime wideband communication networks including the architecture, framework, operations and a comprehensive survey on current developments. The second part of the brief presents the resource allocation and scheduling for video packet transmission wit

  2. National Convective Weather Diagnostic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current convective hazards identified by the National Convective Weather Detection algorithm. The National Convective Weather Diagnostic (NCWD) is an automatically...

  3. Precipitating clouds observed by 1.3-GHz boundary layer radars in equatorial Indonesia

    Directory of Open Access Journals (Sweden)

    F. Renggono

    2001-08-01

    Full Text Available Temporal variations of precipitating clouds in equatorial Indonesia have been studied based on observations with 1357.5 MHz boundary layer radars at Serpong (6.4° S, 106.7° E near Jakarta and Bukittinggi (0.2° S, 100.3° E in West Sumatera. We have classified precipitating clouds into four types: stratiform, mixed stratiform-convective, deep convective, and shallow convective clouds, using the Williams et al. (1995 method. Diurnal variations of the occurrence of precipitating clouds at Serpong and Bukittinggi have showed the same characteristics, namely, that the precipitating clouds primarily occur in the afternoon and the peak of the stratiform cloud comes after the peak of the deep convective cloud. The time delay between the peaks of stratiform and deep convective clouds corresponds to the life cycle of the mesoscale convective system. The precipitating clouds which occur in the early morning at Serpong are dominated by stratiform cloud. Concerning seasonal variations of the precipitating clouds, we have found that the occurrence of the stratiform cloud is most frequent in the rainy season, while the occurrence of the deep convective cloud is predominant in the dry season.Key words. Meteorology and atmospheric dynamics (convective processes; precipitation; tropical meteorology

  4. 78 FR 31809 - National Maritime Day, 2013

    Science.gov (United States)

    2013-05-24

    ... Vol. 78 Friday, No. 101 May 24, 2013 Part VI The President Proclamation 8985--National Maritime... Maritime Day, 2013 By the President of the United States of America A Proclamation Through every chapter of... economic growth by shipping our products all around the world. On National Maritime Day, we honor the...

  5. Maritime Cyber Security University Research: Phase 1

    Science.gov (United States)

    2016-05-01

    i Classification | CG-926 RDC | author | audience | month year Maritime Cyber Security University Research Phase I - Final Report...Appendices Distribution Statement A: Approved for public release; distribution is unlimited. May 2016 Report No. CG-D-07-16 Maritime ...Macesker Executive Director United States Coast Guard Research & Development Center 1 Chelsea Street New London, CT 06320 Maritime Cyber Security

  6. Documenting Maritime Folklife: An Introductory Guide.

    Science.gov (United States)

    Taylor, David A.

    This booklet has two main purposes: (1) to promote understanding of maritime cultural heritage; and (2) to provide an introduction to the methods for identifying and documenting common maritime traditions. The guide is intended for non-professional researchers and community groups who wish to explore their own maritime cultural heritage. It also…

  7. Unmanned Maritime Systems Incremental Acquisition Approach

    Science.gov (United States)

    2016-12-01

    REPORT TYPE AND DATES COVERED MBA professional report 4. TITLE AND SUBTITLE UNMANNED MARITIME SYSTEMS INCREMENTAL ACQUISITION APPROACH 5. FUNDING...Approved for public release. Distribution is unlimited. UNMANNED MARITIME SYSTEMS INCREMENTAL ACQUISITION APPROACH Thomas Driscoll, Lieutenant...UNMANNED MARITIME SYSTEMS INCREMENTAL ACQUISITION APPROACH ABSTRACT The purpose of this MBA report is to explore and understand the issues

  8. Risk assessment in maritime transportation

    International Nuclear Information System (INIS)

    Soares, C. Guedes; Teixeira, A.P.

    2001-01-01

    A review is presented of different approaches to quantify the risk in maritime transportation. The discussion of several accident statistics provides a global assessment of the risk levels and its differentiation in ship types and main types of ship losses. Early studies in the probability of ship loss by foundering and capsizing are reviewed. The approaches used to assess the risk of structural design are addressed. Finally a brief account is given of recent development of using formal safety assessments to support decision making on legislation applicable internationally to maritime transportation

  9. Observational evidence for the aerosol impact on ice cloud properties regulated by cloud/aerosol types

    Science.gov (United States)

    Zhao, B.; Gu, Y.; Liou, K. N.; Jiang, J. H.; Li, Q.; Liu, X.; Huang, L.; Wang, Y.; Su, H.

    2017-12-01

    The interactions between aerosols and ice clouds (consisting only of ice) represent one of the largest uncertainties in global radiative forcing from pre-industrial time to the present. The observational evidence for the aerosol impact on ice cloud properties has been quite limited and showed conflicting results, partly because previous observational studies did not consider the distinct features of different ice cloud and aerosol types. Using 9-year satellite observations, we find that, for ice clouds generated from deep convection, cloud thickness, cloud optical thickness (COT), and ice cloud fraction increase and decrease with small-to-moderate and high aerosol loadings, respectively. For in-situ formed ice clouds, however, the preceding cloud properties increase monotonically and more sharply with aerosol loadings. The case is more complicated for ice crystal effective radius (Rei). For both convection-generated and in-situ ice clouds, the responses of Rei to aerosol loadings are modulated by water vapor amount in conjunction with several other meteorological parameters, but the sensitivities of Rei to aerosols under the same water vapor amount differ remarkably between the two ice cloud types. As a result, overall Rei slightly increases with aerosol loading for convection-generated ice clouds, but decreases for in-situ ice clouds. When aerosols are decomposed into different types, an increase in the loading of smoke aerosols generally leads to a decrease in COT of convection-generated ice clouds, while the reverse is true for dust and anthropogenic pollution. In contrast, an increase in the loading of any aerosol type can significantly enhance COT of in-situ ice clouds. The modulation of the aerosol impacts by cloud/aerosol types is demonstrated and reproduced by simulations using the Weather Research and Forecasting (WRF) model. Adequate and accurate representations of the impact of different cloud/aerosol types in climate models are crucial for reducing the

  10. Dynamics of the Marine Cloud Layers

    National Research Council Canada - National Science Library

    Chi, Joseph

    1999-01-01

    Goals of this research have been to identify physical processes that determine the dynamics of marine cloud layers and to quantify roles of turbulence, convection and thermal radiation that play in formation...

  11. Maritime archaeological studies in India

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Vora, K.H.

    India with more than 7000 km long coastline and about 5000 years old maritime history is dotted with several ancient ports. Marine archaeological research during last two and half decades has revealed a number of sites along the Indian coast, which...

  12. Maritime Security in West Africa

    DEFF Research Database (Denmark)

    Jacobsen, Katja; Nordby, Johannes Riber

    The problem of maritime insecurity in the Gulf of Guinea is not a new phenomenon, but a contemporary form of piracy in the Gulf of Guinea has arguably developed over the past 25 years to be more organized and violent. Besides the issue of how the phenomenon of piracy in the Gulf of Guinea has...

  13. The Maritime Potential of ASEAN Economies

    Directory of Open Access Journals (Sweden)

    Hans-Dieter Evers

    2011-01-01

    Full Text Available Countries may utilize a long coastline in relation to their landmass as a resource to develop their maritime economy. This paper argues that ASEAN countries differ in utilizing their maritime potential. As a basis for further comparative studies the Center for Policy Research and International Studies (CenPRIS in Penang developed a set of indicators to measure the maritime potential of nations, the state of their maritime industries, and the degree to which the maritime potential has actually been utilized. Using the CenPRIS Ocean Index (COI shows that Brunei and the Philippines have underutilized their maritime potentials, whereas Singapore and Thailand have made full use of it. Malaysia still has the potential to further develop its maritime economy.

  14. Maritime Policy and the Seafaring Labor Market

    DEFF Research Database (Denmark)

    Lobrigo, Enrico; Pawlik, Thomas

    2015-01-01

    The reports highlighting the foreseen lack of merchant marine officers for the expanding world’s fleet calls for a review in evaluating the impact of maritime policy in the seafaring labor market. This paper aims to clarify the particular characteristics of the seafaring labor market and how it can...... be shaped by specific maritime labor policies. The seafaring labor market in the Philippines, Poland, Germany, and Brazil as well as the general maritime labor policies in these countries is discussed. The focus on these countries leads to a comparative observation of maritime labor as a factor...... of production in an exporting market, in an importing market, and in a closed market, respectively, as shaped by various relevant maritime policies. Since a global policy that can regulate the maritime labor market does not exist, the trend on maritime labor supply is dynamic on a per country basis wherein crew...

  15. Potential indirect effects of aerosol on tropical cyclone intensity: convective fluxes and cold-pool activity

    Science.gov (United States)

    Krall, G. M.; Cottom, W. R.

    2012-01-01

    Observational and model evidence suggest that a 2008 Western Pacific typhoon (NURI) ingested elevated concentrations of aerosol as it neared the Chinese coast. This study uses a regional model with two-moment bin-emulating microphysics to simulate the typhoon as it enters the field of elevated aerosol concentrations. A clean maritime field of cloud condensation nuclei (CCN) was prescribed as marine background CCN concentrations and then based on satellite and global aerosol model output, increased to pollution levels and further enhanced in sensitivity tests. The typhoon was simulated for 96 h beginning 17 August 2008. During the final 60 h CCN concentrations were enhanced as it neared the Philippines and coastal China. The model was initialized with both global reanalysis model data and irregularly spaced dropsonde data from the 2008 T-PARC observational campaign using an objective analysis routine. At 36 h, the internal nudging of the model was switched off and allowed to freely evolve on its own. As the typhoon encountered the elevated CCN in the sensitivity tests, a significant perturbation of windspeed, convective fluxes, and hydrometeor species behavior was simulated. Early during the ingestion of enhanced CCN, precipitation was reduced due to suppressed collision and coalescence, and storm winds increased in strength. Subsequently, owing to reduced fall speeds of the smaller drops, greater amounts of condensate were thrust into supercooled levels where the drops froze releasing greater amounts of latent heat of freezing. Convection thereby intensified which resulted in enhanced rainfall and more vigorous convectively-produced downdrafts. As the convection intensified in the outer rainbands the storm drifted over the developing cold-pools. The enhanced cold-pools blocked the inflow of warm, moist air into the core of the typhoon which led to a weakening of the typhoon with significantly reduced low level wind speeds. The very high amounts of pollution

  16. Charting a course to maritime excellence in South Africa

    CSIR Research Space (South Africa)

    Funke, Nicola S

    2017-10-01

    Full Text Available maritime culture and recognise and learn from our maritime history 1 Foster national maritime pride 3 Develop and communicate a co-authored discourse on South Africa’s maritime history 2 Support maritime historical and archaeological research, training... world-class education and training facilities 6 Build and retain skills in the maritime sector 2 Support and develop maritime-focused technology and innovation 7 Conduct humanities and social science research on pertinent issues 3 Create knowledge...

  17. Thermodynamic control of anvil cloud amount

    Science.gov (United States)

    Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A.; Voigt, Aiko

    2016-01-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation. PMID:27412863

  18. Introducing Subrid-scale Cloud Feedbacks to Radiation for Regional Meteorological and Cllimate Modeling

    Science.gov (United States)

    Convection systems and associated cloudiness directly influence regional and local radiation budgets, and dynamics and thermodynamics through feedbacks. However, most subgrid-scale convective parameterizations in regional weather and climate models do not consider cumulus cloud ...

  19. Southern Ocean Convection and tropical telleconnections

    Science.gov (United States)

    Marinov, I.; Cabre, A.; Gnanadesikan, A.

    2014-12-01

    We show that Southern Ocean (SO) temperatures in the latest generation of Earth System Models exhibit two major modes of variation, one driven by deep convection, the other by tropical variability. We perform a CMIP5 model intercomparison to understand why different climate models represent SO variability so differently in long, control simulations. We show that multiyear variability in Southern Ocean sea surface temperatures (SSTs) can in turn influence oceanic and atmospheric conditions in the tropics on short (atmospheric) time-scales. We argue that the strength and pattern of SO-tropical teleconnections depends on the intensity of SO deep convection. Periodic convection in the SO is a feature of most CMIP5 models under preindustrial forcing (deLavergne et al., 2014). Models show a wide distribution in the spatial extent, periodicity and intensity of their SO convection, with some models convecting most of the time, and some showing very little convection. In a highly convective coupled model, we find that multidecadal variability in SO and global SSTs, as well as SO heat storage are driven by Weddell Sea convective variability, with convective decades relatively warm due to the heat released from the deep southern ocean and non-convective decades cold due to the subsurface storage of heat. Furthermore, pulses of SO convection drive SST and sea ice variations, influencing absorbed shortwave and emitted longwave radiation, wind, cloud and precipitation patterns, with climatic implications for the low latitudes via fast atmospheric teleconnections. We suggest that these high-low latitude teleconnection mechanisms are relevant for understanding hiatus decades. Additionally, Southern Ocean deep convection varied significantly during past, natural climate changes such as during the last deglaciation. Weddell Sea open convection was recently weakened, likely as a consequence of anthropogenic forcing and the resulting surface freshening. Our study opens up the

  20. 47 CFR 80.1069 - Maritime sea areas.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Maritime sea areas. 80.1069 Section 80.1069... MARITIME SERVICES Global Maritime Distress and Safety System (GMDSS) General Provisions § 80.1069 Maritime... continuous DSC alerting is available as defined by the International Maritime Organization. (2) Sea area A2...

  1. 33 CFR 101.405 - Maritime Security (MARSEC) Directives.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maritime Security (MARSEC... SECURITY MARITIME SECURITY MARITIME SECURITY: GENERAL Control Measures for Security § 101.405 Maritime... necessary to respond to a threat assessment or to a specific threat against the maritime elements of the...

  2. A process-level attribution of the annual cycle of surface temperature over the Maritime Continent

    Science.gov (United States)

    Li, Yana; Yang, Song; Deng, Yi; Hu, Xiaoming; Cai, Ming

    2017-12-01

    The annual cycle of the surface temperature over the Maritime Continent (MC) is characterized by two periods of rapid warming in March-April and September-October, respectively, and a period of rapid cooling in June-July. Based upon an analysis of energy balance within individual atmosphere-surface columns, the seasonal variations of surface temperature in the MC are partitioned into partial temperature changes associated with various radiative and non-radiative (dynamical) processes. The seasonal variations in direct solar forcing and surface latent heat flux show the largest positive contributions to the annual cycle of MC surface temperature while the changes in oceanic dynamics (including ocean heat content change) work against the temperature changes related to the annual cycle. The rapid warming in March-April is mainly a result of the changes in atmospheric quick processes and ocean-atmosphere coupling such as water vapor, surface latent heat flux, clouds, and atmospheric dynamics while the contributions from direct solar forcing and oceanic dynamics are negative. This feature is in contrast to that associated with the warming in September-October, which is driven mainly by the changes in solar forcing with a certain amount of contributions from water vapor and latent heat flux change. More contribution from atmospheric quick processes and ocean-atmosphere coupling in March-April coincides with the sudden northward movement of deep convection belt, while less contribution from these quick processes and coupling is accompanied with the convection belt slowly moving southward. The main contributors to the rapid cooling in June-July are the same as those to the rapid warming in March-April, and the cooling is also negatively contributed by direct solar forcing and oceanic dynamics. The changes in water vapor in all three periods contribute positively to the change in total temperature and they are associated with the change in the location of the center of

  3. Ubiquity and impact of thin mid-level clouds in the tropics

    OpenAIRE

    Bourgeois, Quentin; Ekman, Annica M. L.; Igel, Matthew R.; Krejci, Radovan

    2016-01-01

    Clouds are crucial for Earth's climate and radiation budget. Great attention has been paid to low, high and vertically thick tropospheric clouds such as stratus, cirrus and deep convective clouds. However, much less is known about tropospheric mid-level clouds as these clouds are challenging to observe in situ and difficult to detect by remote sensing techniques. Here we use Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite observations to show that thin mid-level clouds (TM...

  4. Hybrid Maritime Satellite Communication Antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst

    Hybrid antennas for a maritime satellite communication terminal with simultaneous operation at L- and Ka-band have been investigated. The frequency bands of interest are 1; 525:0 1; 660:5 MHz (RX+TX, RHCP), 19:7 20:2 (RX, LHCP) and 29:5 30:0 GHz (TX, RHCP), which are all part of the Inmarsat BGAN...

  5. Maritime adaptive optics beam control

    OpenAIRE

    Corley, Melissa S.

    2010-01-01

    The Navy is interested in developing systems for horizontal, near ocean surface, high-energy laser propagation through the atmosphere. Laser propagation in the maritime environment requires adaptive optics control of aberrations caused by atmospheric distortion. In this research, a multichannel transverse adaptive filter is formulated in Matlab's Simulink environment and compared to a complex lattice filter that has previously been implemented in large system simulations. The adaptive fil...

  6. National Plan to Achieve Maritime Domain Awareness for the National Strategy for Maritime Security

    National Research Council Canada - National Science Library

    2005-01-01

    Maritime Domain Awareness (MDA) is the effective understanding of anything associated with the global maritime domain that could impact the security, safety, economy, or environment of the United States...

  7. International research collaboration in maritime health

    DEFF Research Database (Denmark)

    Jensen, Olaf Chresten

    2011-01-01

    . The area is regulated by international standards based on international research-based knowledge on health and safety. Moreover, many of the world's seafarers come from developing countries with specific disease problems like HIV and no possibility of independent maritime health research. The international......The new ILO-2006-convention and the EU Commission's strategic objectives for the EU maritime transport policy 2008-2018, mentions the necessity of a modern health and safety system for maritime transportation. However, there is no specific strategy for the development of maritime health and safety...... maritime health research is sparse, and an increase in such research is necessary to help benefit needed shipping as a highly globalized industry. This paper presents an example of such research, accompanied by a discussion of methods and opportunities to increase international maritime health research....

  8. Rain-shadow: An area harboring "Gray Ocean" clouds

    Science.gov (United States)

    Padmakumari, B.; Maheskumar, R. S.; Harikishan, G.; Morwal, S. B.; Kulkarni, J. R.

    2018-06-01

    The characteristics of monsoon convective clouds over the rain-shadow region of north peninsular India have been investigated using in situ aircraft cloud microphysical observations collected during Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX). The parameters considered for characterization are: liquid water content (LWC), cloud vertical motion (updraft, downdraft: w), cloud droplet number concentration (CDNC) and effective radius (Re). The results are based on 15 research flights which were conducted from the base station Hyderabad during summer monsoon season. The clouds studied were developing congestus. The clouds have low CDNC and low updraft values resembling the oceanic convective clouds. The super-saturation in clouds is found to be low (≤0.2%) due to low updrafts. The land surface behaves like ocean surface during monsoon as deduced from Bowen ratio. Microphysically the clouds showed oceanic characteristics. However, these clouds yield low rainfall due to their low efficiency (mean 14%). The cloud parameters showed a large variability; hence their characteristic values are reported in terms of median values. These values will serve the numerical models for rainfall simulations over the region and also will be useful as a scientific basis for cloud seeding operations to increase the rainfall efficiency. The study revealed that monsoon convective clouds over the rain-shadow region are of oceanic type over the gray land, and therefore we christen them as "Gray Ocean" clouds.

  9. Satellite remote sensing and cloud modeling of St. Anthony, Minnesota storm clouds and dew point depression

    Science.gov (United States)

    Hung, R. J.; Tsao, Y. D.

    1988-01-01

    Rawinsonde data and geosynchronous satellite imagery were used to investigate the life cycles of St. Anthony, Minnesota's severe convective storms. It is found that the fully developed storm clouds, with overshooting cloud tops penetrating above the tropopause, collapsed about three minutes before the touchdown of the tornadoes. Results indicate that the probability of producing an outbreak of tornadoes causing greater damage increases when there are higher values of potential energy storage per unit area for overshooting cloud tops penetrating the tropopause. It is also found that there is less chance for clouds with a lower moisture content to be outgrown as a storm cloud than clouds with a higher moisture content.

  10. Transregional Threats and Maritime Security Cooperation

    Science.gov (United States)

    2017-08-01

    continue to grow. As of 2015, China’s coast guard had 205 ships, more than the combined coast guards of Japan, Vietnam, Indonesia, Malaysia , and the...raised the possibility of China assisting the Philippines in maritime security. • China has maritime security initiatives with Malaysia and...Pakistan. They have also conducted maritime safety drills with their Omani counterparts. In recent years, the IRIN has made efforts to operate well

  11. Maritime Geo-Fence Letter Report

    Science.gov (United States)

    2016-07-01

    1 Classification | CG-926 RDC | author | audience | month year Maritime Geo-Fence Letter Report Authors: Irene Gonin and Gregory...Johnson   Distribution Statement A: Approved for public release; distribution is unlimited. July 2016 Report No. CG-D-10-16 Maritime Geo-Fence...United States Coast Guard Research & Development Center 1 Chelsea Street New London, CT 06320 Maritime Geo-Fence Letter Report 1

  12. Evidence for island effects and diurnal signals in satellite images of clouds over the tropical western pacific

    Energy Technology Data Exchange (ETDEWEB)

    Barr-Kumarakulasinghe, S.A. [State Univ. of New York, Stony Brook, NY (United States); Reynolds, R.M.; Minnett, P.J. [Brookhaven National Lab., Upton, NY (United States)

    1996-04-01

    Instruments to measure atmospheric radiation and ancillary meteorological variables will be set up on Manus Island as the first site of the tropical western pacific (TWP) locale of the Atmospheric Radiation Measurements (ARM) program. Manus is in the {open_quotes}warm pool{close_quotes} region of the TWP. This region is critical in establishing global atmospheric circulation patterns and is a primary energy source for the Hadley and Walker cells. The myriad islands and enclosed seas in the immediate vicinity of Manus have been referred to as the {open_quotes}maritime continent{close_quotes}, which has the deepest convective activity in the world. Manus is in a region having a global impact on climate and where island effects on clouds are likely to be important. In this preliminary analysis we have sought evidence of island effects in the cloud fields around Manus and have studied the variability of the diurnal cycles of cloud cover over Manus and over other islands and areas of open sea in the region.

  13. Maritime Domain Awareness Architecture Management Hub Strategy

    National Research Council Canada - National Science Library

    2008-01-01

    This document provides an initial high level strategy for carrying out the responsibilities of the national Maritime Domain Awareness Architecture Management Hub to deliver a standards based service...

  14. 77 FR 28894 - Maritime Vulnerability Self-Assessment Tool

    Science.gov (United States)

    2012-05-16

    ... DEPARTMENT OF HOMELAND SECURITY Transportation Security Administration Maritime Vulnerability Self... maritime vulnerability self- assessment tool. SUMMARY: The Transportation Security Administration (TSA) announces that the TSA Maritime Self-Assessment Risk Module (TMSARM), developed to support the United States...

  15. Convective Cold Pool Structure and Boundary Layer Recovery in DYNAMO

    Science.gov (United States)

    Savarin, A.; Chen, S. S.; Kerns, B. W.; Lee, C.; Jorgensen, D. P.

    2012-12-01

    One of the key factors controlling convective cloud systems in the Madden-Julian Oscillation (MJO) over the tropical Indian Ocean is the property of the atmospheric boundary layer. Convective downdrafts and precipitation from the cloud systems produce cold pools in the boundary layer, which can inhibit subsequent development of convection. The recovery time is the time it takes for the boundary layer to return to pre convective conditions. It may affect the variability of the convection on various time scales during the initiation of MJO. This study examines the convective cold pool structure and boundary layer recovery using the NOAA WP-3D aircraft observations, include the flight-level, Doppler radar, and GPS dropsonde data, collected during the Dynamics of MJO (DYNAMO) field campaign from November-December 2011. The depth and strength of convective cold pools are defined by the negative buoyancy, which can be computed from the dropsonde data. Convective downdraft can be affected by environmental water vapor due to entrainment. Mid-level dry air observed during the convectively suppressed phase of MJO seems to enhance convective downdraft, making the cold pools stronger and deeper. Recovery of the cold pools in the boundary layer is determined by the strength and depth of the cold pools and also the air-sea heat and moisture fluxes. Given that the water vapor and surface winds are distinct for the convectively active and suppressed phases of MJO over the Indian Ocean, the aircraft data are stratified by the two different large-scale regimes of MJO. Preliminary results show that the strength and depth of the cold pools are inversely correlated with the surrounding mid-level moisture. During the convectively suppressed phase, the recovery time is ~5-20 hours in relative weak wind condition with small air-sea fluxes. The recovery time is generally less than 6 hours during the active phase of MJO with moist mid-levels and stronger surface wind and air-sea fluxes.

  16. Maritime Security – The Need for a Global Agreement

    OpenAIRE

    Dinos Stasinopoulos

    2003-01-01

    This note reviews US maritime security measures, outlines work carried out by international organisations and then frames maritime security within the wider context of maritime trade. Finally, it suggests the development of a Global Agreement linking security and other maritime trade-related issues. The initiative for such an agreement should be undertaken by the EU only if current International Maritime Organisation (IMO) efforts fail to produce a maritime security framework with binding req...

  17. GPM GROUND VALIDATION NCAR CLOUD MICROPHYSICS PARTICLE PROBES MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E dataset was collected during the Midlatitude Continental Convective Clouds Experiment (MC3E),...

  18. 33 CFR 103.310 - Responsibilities of the Area Maritime Security (AMS) Committee.

    Science.gov (United States)

    2010-07-01

    ... disseminating appropriate security information to port stakeholders. ... Maritime Security (AMS) Committee. 103.310 Section 103.310 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARITIME SECURITY: AREA MARITIME SECURITY Area Maritime...

  19. The diurnal interaction between convection and peninsular-scale forcing over South Florida

    Science.gov (United States)

    Cooper, H. J.; Simpson, J.; Garstang, M.

    1982-01-01

    One of the outstanding problems in modern meterology is that of describing in detail the manner in which larger scales of motion interact with, influence and are influenced by successively smaller scales of motion. The present investigation is concerned with a study of the diurnal evolution of convection, the interaction between the peninsular-scale convergence and convection, and the role of the feedback produced by the cloud-scale downdrafts in the maintenance of the convection. Attention is given to the analysis, the diurnal cycle of the network area-averaged divergence, convective-scale divergence, convective mass transports, and the peninsular scale divergence. The links established in the investigation between the large scale (peninsular), the mesoscale (network), and the convective scale (cloud) are found to be of fundamental importance to the understanding of the initiation, maintenance, and decay of deep precipitating convection and to its theoretical parameterization.

  20. National Convective Weather Forecast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NCWF is an automatically generated depiction of: (1) current convection and (2) extrapolated signficant current convection. It is a supplement to, but does NOT...

  1. Evaluation of convection-resolving models using satellite data: The diurnal cycle of summer convection over the Alps

    Directory of Open Access Journals (Sweden)

    Michael Keller

    2016-05-01

    Full Text Available Diurnal moist convection is an important element of summer precipitation over Central Europe and the Alps. It is poorly represented in models using parameterized convection. In this study, we investigate the diurnal cycle of convection during 11 days in June 2007 using the COSMO model. The numerical simulations are compared with satellite measurements of GERB and SEVIRI, AVHRR satellite-based cloud properties and ground-based precipitation and temperature measurements. The simulations use horizontal resolutions of 12 km (convection-parameterizing model, CPM and 2 km (convection-resolving model, CRM and either a one-moment microphysics scheme (1M or a two-moment microphysics scheme (2M.They are conducted for a computational domain that covers an extended Alpine area from Northern Italy to Northern Germany. The CPM with 1M exhibits a significant overestimation of high cloud cover. This results in a compensation effect in the top of the atmosphere energy budget due to an underestimation of outgoing longwave radiation (OLR and an overestimation of reflected solar radiation (RSR. The CRM reduces high cloud cover and improves the OLR bias from a domain mean of −20.1 to −2.6 W/m2. When using 2M with ice sedimentation in the CRM, high cloud cover is further reduced. The stronger diurnal cycle of high cloud cover and associated convection over the Alps, compared to less mountainous regions, is well represented by the CRM but underestimated by the CPM. Despite substantial differences in high cloud cover, the use of a 2M has no significant impact on the diurnal cycle of precipitation. Furthermore, a negative mid-level cloud bias is found for all simulations.

  2. Maritime environmental penal law. International and German legislation; Maritimes Umweltstrafrecht. Voelkerrechtliche Grundlagen und deutsches Recht

    Energy Technology Data Exchange (ETDEWEB)

    Eller, Jan Frederik

    2017-07-01

    The book on maritime environmental penal law discusses the following issues: part I: introduction into the importance of oceanic environment and its thread, requirement of protective measures,; part II: focus of the study and terminology: oceanic pollution, maritime environmental legislation, international legislation; part 3: international legislative regulations concerning the protection of maritime environment: avoidance of environmental pollution, maritime legislative agreements, existing protective institutions; part 4: state penal power concerning maritime environmental protection; part 5: statutory offense according to German legislation; perspectives for regulations concerning criminal acts on sea.

  3. Aerosols' influence on the interplay between condensation, evaporation and rain in warm cumulus cloud

    Directory of Open Access Journals (Sweden)

    O. Altaratz

    2008-01-01

    Full Text Available A numerical cloud model is used to study the influence of aerosol on the microphysics and dynamics of moderate-sized, coastal, convective clouds that develop under the same meteorological conditions. The results show that polluted convective clouds start their precipitation later and precipitate less than clean clouds but produce larger rain drops. The evaporation process is more significant at the margins of the polluted clouds (compared to the clean cloud due to a higher drop surface area to volume ratio and it is mostly from small drops. It was found that the formation of larger raindrops in the polluted cloud is due to a more efficient collection process.

  4. Maritim epidemiologi på Supercourse

    DEFF Research Database (Denmark)

    Jensen, Olaf

    2015-01-01

    Maritim epidemiologi er nu kommet med i samlingen af undervisningsmidler på ”Supercourse”. Der er oprettet en særlig mappe med Maritime Epidemiology og alle der har gode bidrag inden for området opfordres hermed til at publicere her. Supercourse er en samling af foredrag beregnet til at være en r...

  5. On English Teaching in Maritime Colleges

    Science.gov (United States)

    Shen, Jiang; Wang, Honggui

    2011-01-01

    According to English level of Chinese ocean sailors at present, we analyze the characteristics and instruction needs of navigation English and point out current English teaching in maritime specialty has many problems. Traditional teaching modes are not suitable for modern maritime needs any longer. So we propose feasible methods and…

  6. The Irish Maritime Transport Economist Volume 3

    OpenAIRE

    Office, Irish Maritime Development

    2006-01-01

    The Irish Maritime Development Office (IMDO) of the Marine Institute publishes the Irish Maritime Transport Economist each year to provide a descriptive statistical analysis of the Irish ports and shipping services sector, as well as the many factors influencing its performance.

  7. The Irish Maritime Transport Economist Volume 4

    OpenAIRE

    Office, Irish Maritime Development

    2007-01-01

    The Irish Maritime Development Office (IMDO) of the Marine Institute publishes the Irish Maritime Transport Economist each year to provide a descriptive statistical analysis of the Irish ports and shipping services sector, as well as the many factors influencing its performance.

  8. Convective Self-Aggregation in Numerical Simulations: A Review

    Science.gov (United States)

    Wing, Allison A.; Emanuel, Kerry; Holloway, Christopher E.; Muller, Caroline

    Organized convection in the tropics occurs across a range of spatial and temporal scales and strongly influences cloud cover and humidity. One mode of organization found is ``self-aggregation,'' in which moist convection spontaneously organizes into one or several isolated clusters despite spatially homogeneous boundary conditions and forcing. Self-aggregation is driven by interactions between clouds, moisture, radiation, surface fluxes, and circulation, and occurs in a wide variety of idealized simulations of radiative-convective equilibrium. Here we provide a review of convective self-aggregation in numerical simulations, including its character, causes, and effects. We describe the evolution of self-aggregation including its time and length scales and the physical mechanisms leading to its triggering and maintenance, and we also discuss possible links to climate and climate change.

  9. Overview and outlook for Maritime markets

    International Nuclear Information System (INIS)

    Kirstiuk, S.

    1998-01-01

    The potential of the Maritime provinces as being among the world leaders in manufacturing and value-added resource processing, low unemployment and steady economic growth was explored. Irving Oil and J.D. Irving Ltd., have actively participated in supporting the Sable Offshore Energy Project and Maritimes and Northeast Projects because of the promise of tremendous economic benefits the projects will have on the Maritime provinces. It was predicted that the projects will create thousands of jobs in Nova Scotia and New Brunswick, but more importantly, they will make the region more cost-effective and more competitive in the global markets. The Sable offshore project will allow Maritimers to compete internationally on a level playing field. With gas becoming available in the region, the opportunity exists to generate electricity at lower costs using natural gas turbines and co-generation facilities. Cheaper electricity will create new opportunities for further industrial expansion, more jobs and a stronger economy for the Maritime provinces

  10. Life Cycle of Tropical Convection and Anvil in Observations and Models

    Science.gov (United States)

    McFarlane, S. A.; Hagos, S. M.; Comstock, J. M.

    2011-12-01

    Tropical convective clouds are important elements of the hydrological cycle and produce extensive cirrus anvils that strongly affect the tropical radiative energy balance. To improve simulations of the global water and energy cycles and accurately predict both precipitation and cloud radiative feedbacks, models need to realistically simulate the lifecycle of tropical convection, including the formation and radiative properties of ice anvil clouds. By combining remote sensing datasets from precipitation and cloud radars at the Atmospheric Radiation Measurement (ARM) Darwin site with geostationary satellite data, we can develop observational understanding of the lifetime of convective systems and the links between the properties of convective systems and their associated anvil clouds. The relationships between convection and anvil in model simulations can then be compared to those seen in the observations to identify areas for improvement in the model simulations. We identify and track tropical convective systems in the Tropical Western Pacific using geostationary satellite observations. We present statistics of the tropical convective systems including size, age, and intensity and classify the lifecycle stage of each system as developing, mature, or dissipating. For systems that cross over the ARM Darwin site, information on convective intensity and anvil properties are obtained from the C-Pol precipitation radar and MMCR cloud radar, respectively, and are examined as a function of the system lifecycle. Initial results from applying the convective identification and tracking algorithm to a tropical simulation from the Weather Research and Forecasting (WRF) model run show that the model produces reasonable overall statistics of convective systems, but details of the life cycle (such as diurnal cycle, system tracks) differ from the observations. Further work will focus on the role of atmospheric temperature and moisture profiles in the model's convective life cycle.

  11. Assumed Probability Density Functions for Shallow and Deep Convection

    OpenAIRE

    Steven K Krueger; Peter A Bogenschutz; Marat Khairoutdinov

    2010-01-01

    The assumed joint probability density function (PDF) between vertical velocity and conserved temperature and total water scalars has been suggested to be a relatively computationally inexpensive and unified subgrid-scale (SGS) parameterization for boundary layer clouds and turbulent moments. This paper analyzes the performance of five families of PDFs using large-eddy simulations of deep convection, shallow convection, and a transition from stratocumulus to trade wind cumulus. Three of the PD...

  12. Convergence behavior of idealized convection-resolving simulations of summertime deep moist convection over land

    Science.gov (United States)

    Panosetti, Davide; Schlemmer, Linda; Schär, Christoph

    2018-05-01

    Convection-resolving models (CRMs) can explicitly simulate deep convection and resolve interactions between convective updrafts. They are thus increasingly used in numerous weather and climate applications. However, the truncation of the continuous energy cascade at scales of O (1 km) poses a serious challenge, as in kilometer-scale simulations the size and properties of the simulated convective cells are often determined by the horizontal grid spacing (Δ x ).In this study, idealized simulations of deep moist convection over land are performed to assess the convergence behavior of a CRM at Δ x = 8, 4, 2, 1 km and 500 m. Two types of convergence estimates are investigated: bulk convergence addressing domain-averaged and integrated variables related to the water and energy budgets, and structural convergence addressing the statistics and scales of individual clouds and updrafts. Results show that bulk convergence generally begins at Δ x =4 km, while structural convergence is not yet fully achieved at the kilometer scale, despite some evidence that the resolution sensitivity of updraft velocities and convective mass fluxes decreases at finer resolution. In particular, at finer grid spacings the maximum updraft velocity generally increases, and the size of the smallest clouds is mostly determined by Δ x . A number of different experiments are conducted, and it is found that the presence of orography and environmental vertical wind shear yields more energetic structures at scales much larger than Δ x , sometimes reducing the resolution sensitivity. Overall the results lend support to the use of kilometer-scale resolutions in CRMs, despite the inability of these models to fully resolve the associated cloud field.

  13. Climatology and Impact of Convection on the Tropical Tropopause Layer

    Science.gov (United States)

    Robertson, Franklin; Pittman, Jasna

    2007-01-01

    Water vapor plays an important role in controlling the radiative balance and the chemical composition of the Tropical Tropopause Layer (TTL). Mechanisms ranging from slow transport and dehydration under thermodynamic equilibrium conditions to fast transport in convection have been proposed as regulators of the amount of water vapor in this layer. However,.details of these mechanisms and their relative importance remain poorly understood, The recently completed Tropical Composition, Cloud, and Climate Coupling (TC4) campaign had the opportunity to sample the.TTL over the Eastern Tropical Pacific using ground-based, airborne, and spaceborne instruments. The main goal of this study is to provide the climatological context for this campaign of deep and overshooting convective activity using various satellite observations collected during the summertime. We use the Microwave Humidity Sensor (MRS) aboard the NOAA-18 satellite to investigate the horizontal extent.and the frequency of convection reaching and penetrating into the TTL. We use the Moderate Resolution I1l1aging Spectroradiometer (MODIS) aboard the Aqua satellite to investigate the frequency distribution of daytime cirrus clouds. We use the Tropical Rainfall Measuring Mission(TRMM) and CloudSat to investigate the vertical structure and distribution of hydrometeors in the convective cells, In addition to cloud measurements; we investigate the impact that convection has on the concentration of radiatively important gases such as water vapor and ozone in the TTL by examining satellite measurement obtained from the Microwave Limb Sounder(MLS) aboard the Aura satellite.

  14. Improving microphysics in a convective parameterization: possibilities and limitations

    Science.gov (United States)

    Labbouz, Laurent; Heikenfeld, Max; Stier, Philip; Morrison, Hugh; Milbrandt, Jason; Protat, Alain; Kipling, Zak

    2017-04-01

    The convective cloud field model (CCFM) is a convective parameterization implemented in the climate model ECHAM6.1-HAM2.2. It represents a population of clouds within each ECHAM-HAM model column, simulating up to 10 different convective cloud types with individual radius, vertical velocities and microphysical properties. Comparisons between CCFM and radar data at Darwin, Australia, show that in order to reproduce both the convective cloud top height distribution and the vertical velocity profile, the effect of aerodynamic drag on the rising parcel has to be considered, along with a reduced entrainment parameter. A new double-moment microphysics (the Predicted Particle Properties scheme, P3) has been implemented in the latest version of CCFM and is compared to the standard single-moment microphysics and the radar retrievals at Darwin. The microphysical process rates (autoconversion, accretion, deposition, freezing, …) and their response to changes in CDNC are investigated and compared to high resolution CRM WRF simulations over the Amazon region. The results shed light on the possibilities and limitations of microphysics improvements in the framework of CCFM and in convective parameterizations in general.

  15. Is Convection Sensitive to Model Vertical Resolution and Why?

    Science.gov (United States)

    Xie, S.; Lin, W.; Zhang, G. J.

    2017-12-01

    Model sensitivity to horizontal resolutions has been studied extensively, whereas model sensitivity to vertical resolution is much less explored. In this study, we use the US Department of Energy (DOE)'s Accelerated Climate Modeling for Energy (ACME) atmosphere model to examine the sensitivity of clouds and precipitation to the increase of vertical resolution of the model. We attempt to understand what results in the behavior change (if any) of convective processes represented by the unified shallow and turbulent scheme named CLUBB (Cloud Layers Unified by Binormals) and the Zhang-McFarlane deep convection scheme in ACME. A short-term hindcast approach is used to isolate parameterization issues from the large-scale circulation. The analysis emphasizes on how the change of vertical resolution could affect precipitation partitioning between convective- and grid-scale as well as the vertical profiles of convection-related quantities such as temperature, humidity, clouds, convective heating and drying, and entrainment and detrainment. The goal is to provide physical insight into potential issues with model convective processes associated with the increase of model vertical resolution. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Convective aggregation in realistic convective-scale simulations

    Science.gov (United States)

    Holloway, Christopher E.

    2017-06-01

    To investigate the real-world relevance of idealized-model convective self-aggregation, five 15 day cases of real organized convection in the tropics are simulated. These include multiple simulations of each case to test sensitivities of the convective organization and mean states to interactive radiation, interactive surface fluxes, and evaporation of rain. These simulations are compared to self-aggregation seen in the same model configured to run in idealized radiative-convective equilibrium. Analysis of the budget of the spatial variance of column-integrated frozen moist static energy shows that control runs have significant positive contributions to organization from radiation and negative contributions from surface fluxes and transport, similar to idealized runs once they become aggregated. Despite identical lateral boundary conditions for all experiments in each case, systematic differences in mean column water vapor (CWV), CWV distribution shape, and CWV autocorrelation length scale are found between the different sensitivity runs, particularly for those without interactive radiation, showing that there are at least some similarities in sensitivities to these feedbacks in both idealized and realistic simulations (although the organization of precipitation shows less sensitivity to interactive radiation). The magnitudes and signs of these systematic differences are consistent with a rough equilibrium between (1) equalization due to advection from the lateral boundaries and (2) disaggregation due to the absence of interactive radiation, implying disaggregation rates comparable to those in idealized runs with aggregated initial conditions and noninteractive radiation. This points to a plausible similarity in the way that radiation feedbacks maintain aggregated convection in both idealized simulations and the real world.Plain Language SummaryUnderstanding the processes that lead to the organization of tropical rainstorms is an important challenge for weather

  17. Maritime Security Concerns of the East African Community (EAC ...

    African Journals Online (AJOL)

    The maritime domain of the East African Community (EAC) is affected by a number of maritime security threats, including piracy, armed robbery against ships and an ongoing maritime border dispute between Kenya and Somalia. Neither the EAC nor its member States have long-term and holistic maritime security policies.

  18. 32 CFR 536.117 - Statutory authority for maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Statutory authority for maritime claims. 536.117... ACCOUNTS CLAIMS AGAINST THE UNITED STATES Maritime Claims § 536.117 Statutory authority for maritime claims. The Army Maritime Claims Settlement Act (AMCSA) (10 U.S.C. 4801-04, 4806, as amended) authorizes the...

  19. 32 CFR 536.118 - Related statutes for maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Related statutes for maritime claims. 536.118... ACCOUNTS CLAIMS AGAINST THE UNITED STATES Maritime Claims § 536.118 Related statutes for maritime claims... under the AMCSA is not mandatory for causes of action as it is for the SIAA or PVA. (b) Similar maritime...

  20. 32 CFR 536.120 - Claims payable as maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Claims payable as maritime claims. 536.120... ACCOUNTS CLAIMS AGAINST THE UNITED STATES Maritime Claims § 536.120 Claims payable as maritime claims. A claim is cognizable under this subpart if it arises in or on a maritime location, involves some...

  1. 32 CFR 537.16 - Scope for maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Scope for maritime claims. 537.16 Section 537.16... BEHALF OF THE UNITED STATES § 537.16 Scope for maritime claims. The Army Maritime Claims Settlement Act... claims for damage to: (1) DA-accountable properties of a kind that are within the federal maritime...

  2. 33 CFR 104.145 - Maritime Security (MARSEC) Directive.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maritime Security (MARSEC) Directive. 104.145 Section 104.145 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARITIME SECURITY: VESSELS General § 104.145 Maritime Security (MARSEC...

  3. 32 CFR 536.119 - Scope for maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Scope for maritime claims. 536.119 Section 536... CLAIMS AGAINST THE UNITED STATES Maritime Claims § 536.119 Scope for maritime claims. The AMCSA applies...) Damage that is maritime in nature and caused by tortious conduct of U.S. military personnel or federal...

  4. 33 CFR 105.145 - Maritime Security (MARSEC) Directive.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maritime Security (MARSEC) Directive. 105.145 Section 105.145 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARITIME SECURITY: FACILITIES General § 105.145 Maritime Security (MARSEC...

  5. 47 CFR 80.1135 - Transmission of maritime safety information.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmission of maritime safety information. 80... RADIO SERVICES STATIONS IN THE MARITIME SERVICES Global Maritime Distress and Safety System (GMDSS) Operating Procedures for Distress and Safety Communications § 80.1135 Transmission of maritime safety...

  6. Routing of platforms in a maritime surface surveillance operation

    NARCIS (Netherlands)

    Grob, M.J.H.B.

    2006-01-01

    Maritime surface surveillance is the process of obtaining and maintaining information about surface ships in a certain sea area. It is carried out by maritime platforms such as frigates, helicopters or maritime patrol aircraft. Surface surveillance plays a vital role in maritime operations like

  7. Maritime English instruction – ensuring instructors’ competence

    Directory of Open Access Journals (Sweden)

    Clive Cole

    2007-10-01

    Full Text Available More than ninety percent of global trade is carried by sea. As a result it “has fostered an interdependency and inter-connectivity between peoples who would previously have considered themselves completely unconnected” (Mitropoulos, 2005. For the maritime industry which facilitates this activity, it is essential that a common working language, namely English, is competently used to safeguard the ship, its crew and the environment in which it sails. This presupposes that the graduates of maritime academies are well prepared and that their mentors are qualified to perform the task required by international regulations. This paper attempts to summarise a 2-year research project, funded by the International Association of Maritime Universities and completed by the authors in 2006, entitled “Profiling the Maritime English Instructor” (PROFS. It categorizes and describes the various types of Maritime English instructors presently employed at higher Maritime Education and Training institutions worldwide, defines the requirements regarding their professional qualifications in the areas of applied linguistics, methodology and the minimum maritime background knowledge demanded by the relevant international legislation, and thus provides a guideline for management and prospective instructors.

  8. Type-Dependent Responses of Ice Cloud Properties to Aerosols From Satellite Retrievals

    Science.gov (United States)

    Zhao, Bin; Gu, Yu; Liou, Kuo-Nan; Wang, Yuan; Liu, Xiaohong; Huang, Lei; Jiang, Jonathan H.; Su, Hui

    2018-04-01

    Aerosol-cloud interactions represent one of the largest uncertainties in external forcings on our climate system. Compared with liquid clouds, the observational evidence for the aerosol impact on ice clouds is much more limited and shows conflicting results, partly because the distinct features of different ice cloud and aerosol types were seldom considered. Using 9-year satellite retrievals, we find that, for convection-generated (anvil) ice clouds, cloud optical thickness, cloud thickness, and cloud fraction increase with small-to-moderate aerosol loadings (types provide valuable constraints on the modeling assessment of aerosol-ice cloud radiative forcing.

  9. Remote sensing of severe convective storms over Qinghai-Xizang Plateau

    Science.gov (United States)

    Hung, R. J.; Liu, J. M.; Tsao, D. Y.; Smith, R. E.

    1984-01-01

    The American satellite, GOES-1 was moved to the Indian Ocean at 58 deg E during the First GARP Global Experiment (FGGE). The Qinghai-Xizang Plateau significantly affects the initiation and development of heavy rainfall and severe storms in China, just as the Rocky Mountains influence the local storms in the United States. Satelite remote sensing of short-lived, meso-scale convective storms is particularly important for covering a huge area of a high elevation with a low population density, such as the Qinghai-Xizang Plateau. Results of this study show that a high growth rate of the convective clouds, followed by a rapid collapse of the cloud top, is associated with heavy rainfall in the area. The tops of the convective clouds developed over the Plateau lie between the altitudes of the two tropopauses, while the tops of convective clouds associated with severe storms in the United States usually extend much above the tropopause.

  10. The maritime transport of nuclear substances

    International Nuclear Information System (INIS)

    Los Santos, A. de; Corretjer, L.

    1976-01-01

    In view of the fact that the regulation of maritime transport of nuclear materials comes under both maritime and nuclear law has raised problems which it was attempted to solve by specific standards. As regards the prevention of nuclear hazards, these standards are based on the recommendations of competent international organizations, while concerning compensation of nuclear damage, a Convention which has just come into force lays down that nuclear law has priority over maritime law. Despite the progress made, a study of the situation in this field shows that it can be further improved. (N.E.A.) [fr

  11. Maritime cleantech entrepreneurship in Frederikshavn, Denmark

    DEFF Research Database (Denmark)

    Hermann, Roberto Rivas; Lunde-Christensen, Jeanne Christine; Riisgaard, Henrik

    2012-01-01

    The demand on maritime cleantech may increase as result new regulations on maritime source air pollutants by International Maritime Organization and the European Union. As result, the demands will also increase for ship retrofit and cleantech installations. Such opportunities may be triggered...... in access to and best use of information. Furthermore, access to information can result from active search, alertness to opportunities, and entrepreneur's previous experience. The Frederikshavn case study may add a fourth element: access to information can result from the facilitation provided...

  12. 32 CFR 537.15 - Statutory authority for maritime claims and claims involving civil works of a maritime nature.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Statutory authority for maritime claims and claims involving civil works of a maritime nature. 537.15 Section 537.15 National Defense Department of....15 Statutory authority for maritime claims and claims involving civil works of a maritime nature. (a...

  13. Transnucleaire's experience in maritime transportation

    International Nuclear Information System (INIS)

    Vallette-Fontaine, M.

    1998-01-01

    Since the INF code requirement has been implemented in early 1995 laying down stringent requirements for ships transporting irradiated nuclear fuel, plutonium and high level radioactive waste, Transnucleaire has upgraded and operates two sister ships belonging a CMN shipping company and is well involved in the maritime transportation of radioactive materials. This paper aims at analysing the various principles implemented by Transnucleaire: operate ships such as Bouguenais and Beaulieu in compliance will all existing regulations such as INF Code, Japanese KAISA...; keep the sea transportation of nuclear material at affordable price for all nuclear organizations especially those involved in research activities; avoid for non routine transports, the use of nuclear dedicated ships often precluded by its high costs; adapt the means to all possible evolutions, i.e. be prepared to offer improved ships to satisfy all the scale of requirements; find optimised technical solutions to comply with Japanese type B ship regulations at a reasonable cost. (authors)

  14. Investigation of tropical diurnal convection biases in a climate model using TWP-ICE observations and convection-permitting simulations

    Science.gov (United States)

    Lin, W.; Xie, S.; Jackson, R. C.; Endo, S.; Vogelmann, A. M.; Collis, S. M.; Golaz, J. C.

    2017-12-01

    Climate models are known to have difficulty in simulating tropical diurnal convections that exhibit distinct characteristics over land and open ocean. While the causes are rooted in deficiencies in convective parameterization in general, lack of representations of mesoscale dynamics in terms of land-sea breeze, convective organization, and propagation of convection-induced gravity waves also play critical roles. In this study, the problem is investigated at the process-level with the U.S. Department of Energy Accelerated Climate Modeling for Energy (ACME) model in short-term hindcast mode using the Cloud Associated Parameterization Testbed (CAPT) framework. Convective-scale radar retrievals and observation-driven convection-permitting simulations for the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) cases are used to guide the analysis of the underlying processes. The emphasis will be on linking deficiencies in representation of detailed process elements to the model biases in diurnal convective properties and their contrast among inland, coastal and open ocean conditions.

  15. Clustering, randomness, and regularity in cloud fields: 2. Cumulus cloud fields

    Science.gov (United States)

    Zhu, T.; Lee, J.; Weger, R. C.; Welch, R. M.

    1992-12-01

    During the last decade a major controversy has been brewing concerning the proper characterization of cumulus convection. The prevailing view has been that cumulus clouds form in clusters, in which cloud spacing is closer than that found for the overall cloud field and which maintains its identity over many cloud lifetimes. This "mutual protection hypothesis" of Randall and Huffman (1980) has been challenged by the "inhibition hypothesis" of Ramirez et al. (1990) which strongly suggests that the spatial distribution of cumuli must tend toward a regular distribution. A dilemma has resulted because observations have been reported to support both hypotheses. The present work reports a detailed analysis of cumulus cloud field spatial distributions based upon Landsat, Advanced Very High Resolution Radiometer, and Skylab data. Both nearest-neighbor and point-to-cloud cumulative distribution function statistics are investigated. The results show unequivocally that when both large and small clouds are included in the cloud field distribution, the cloud field always has a strong clustering signal. The strength of clustering is largest at cloud diameters of about 200-300 m, diminishing with increasing cloud diameter. In many cases, clusters of small clouds are found which are not closely associated with large clouds. As the small clouds are eliminated from consideration, the cloud field typically tends towards regularity. Thus it would appear that the "inhibition hypothesis" of Ramirez and Bras (1990) has been verified for the large clouds. However, these results are based upon the analysis of point processes. A more exact analysis also is made which takes into account the cloud size distributions. Since distinct clouds are by definition nonoverlapping, cloud size effects place a restriction upon the possible locations of clouds in the cloud field. The net effect of this analysis is that the large clouds appear to be randomly distributed, with only weak tendencies towards

  16. Verification of cloud cover forecast with INSAT observation over ...

    Indian Academy of Sciences (India)

    and recent trends in forecast quality, improving ... general framework for forecast verification based on the joint ... clouds is given by POD, and FAR offers a metric for how often the .... Kain J S and Fritsch J M 1993 Convective parameterizations.

  17. 1 Vertical structure of orographic precipitating clouds observed over ...

    Indian Academy of Sciences (India)

    11

    The present study explores the vertical structure of precipitating clouds associated with orographic features in South .... The PR, by design, detects PLW and not CLW. Dryness of ...... Organization of Asian Monsoon Convection*; J. Clim. 19(14) ...

  18. A case study of microphysical structures and hydrometeor phase in convection using radar Doppler spectra at Darwin, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Riihimaki, Laura D.; Comstock, Jennifer M.; Luke, Edward; Thorsen, Tyler J.; Fu, Qiang

    2017-07-28

    To understand the microphysical processes that impact diabatic heating and cloud lifetimes in convection, we need to characterize the spatial distribution of supercooled liquid water. To address this observational challenge, vertically pointing active sensors at the Darwin Atmospheric Radiation Measurement (ARM) site are used to classify cloud phase within a deep convective cloud in a shallow to deep convection transitional case. The cloud cannot be fully observed by a lidar due to signal attenuation. Thus we develop an objective method for identifying hydrometeor classes, including mixed-phase conditions, using k-means clustering on parameters that describe the shape of the Doppler spectra from vertically pointing Ka band cloud radar. This approach shows that multiple, overlapping mixed-phase layers exist within the cloud, rather than a single region of supercooled liquid, indicating complexity to how ice growth and diabatic heating occurs in the vertical structure of the cloud.

  19. Evaluating Microphysics in Cloud-Resolving Models using TRMM and Ground-based Precipitation Radar Observations

    Science.gov (United States)

    Krueger, S. K.; Zulauf, M. A.; Li, Y.; Zipser, E. J.

    2005-05-01

    Global satellite datasets such as those produced by ISCCP, ERBE, and CERES provide strong observational constraints on cloud radiative properties. Such observations have been widely used for model evaluation, tuning, and improvement. Cloud radiative properties depend primarily on small, non-precipitating cloud droplets and ice crystals, yet the dynamical, microphysical and radiative processes which produce these small particles often involve large, precipitating hydrometeors. There now exists a global dataset of tropical cloud system precipitation feature (PF) properties, collected by TRMM and produced by Steve Nesbitt, that provides additional observational constraints on cloud system properties. We are using the TRMM PF dataset to evaluate the precipitation microphysics of two simulations of deep, precipitating, convective cloud systems: one is a 29-day summertime, continental case (ARM Summer 1997 SCM IOP, at the Southern Great Plains site); the second is a tropical maritime case: the Kwajalein MCS of 11-12 August 1999 (part of a 52-day simulation). Both simulations employed the same bulk, three-ice category microphysical parameterization (Krueger et al. 1995). The ARM simulation was executed using the UCLA/Utah 2D CRM, while the KWAJEX simulation was produced using the 3D CSU CRM (SAM). The KWAJEX simulation described above is compared with both the actual radar data and the TRMM statistics. For the Kwajalein MCS of 11 to 12 August 1999, there are research radar data available for the lifetime of the system. This particular MCS was large in size and rained heavily, but it was weak to average in measures of convective intensity, against the 5-year TRMM sample of 108. For the Kwajalein MCS simulation, the 20 dBZ contour is at 15.7 km and the 40 dBZ contour at 14.5 km! Of all 108 MCSs observed by TRMM, the highest value for the 40 dBZ contour is 8 km. Clearly, the high reflectivity cores are off scale compared with observed cloud systems in this area. A similar

  20. SITREP: The NPS Maritime Defense and Security Research Program Newsletter ; v. 48 (July-August 2010)

    OpenAIRE

    2010-01-01

    This issue of The NPS Maritime Domain Protection Newsletter includes information on The Technology Cooperation Program (TTCP) Maritime (MAR), RAND Corporation Maritime Programs, Librarians Corner, and Future Events.

  1. Tropical High Cloud Fraction Controlled by Cloud Lifetime Rather Than Clear-sky Convergence

    Science.gov (United States)

    Seeley, J.; Jeevanjee, N.; Romps, D. M.

    2016-12-01

    Observations and simulations show a peak in cloud fraction below the tropopause. This peak is usually attributed to a roughly co-located peak in radiatively-driven clear-sky convergence, which is presumed to force convective detrainment and thus promote large cloud fraction. Using simulations of radiative-convective equilibrium forced by various radiative cooling profiles, we refute this mechanism by showing that an upper-tropospheric peak in cloud fraction persists even in simulations with no peak in clear-sky convergence. Instead, cloud fraction profiles seem to be controlled by cloud lifetimes — i.e., how long it takes for clouds to dissipate after they have detrained. A simple model of cloud evaporation shows that the small saturation deficit in the upper troposphere greatly extends cloud lifetimes there, while the large saturation deficit in the lower troposphere causes condensate to evaporate quickly. Since cloud mass flux must go to zero at the tropopause, a peak in cloud fraction emerges at a "sweet spot" below the tropopause where cloud lifetimes are long and there is still sufficient mass flux to be detrained.

  2. Impact of Convection on Surface Fluxes Observed During LASP/DYNAMO 2011

    Science.gov (United States)

    2014-12-01

    20  Figure 8.  FFM maneuver used in the LASP/DYNAMO experiment (from Wang et al. 2013...Atmosphere Response Experiment DYNAMO Dynamics of Madden-Julian Oscillation EM electro-magnetic EO electro-optical FFM flight-level flux mapping FVS...level flux mapping ( FFM ) modules. Convection modules consisted of dropsonde cloud survey or radar convective element maneuver. Dropsonde modules

  3. Maritime emergency management capabilities in the Arctic

    DEFF Research Database (Denmark)

    Roud, Ensieh Kheiri Pileh; Borch, Odd Jarl; Jakobsen, Uffe

    2016-01-01

    Growing maritime commercial activities in the High North increase the possibility of unwanted incidents. The vulnerability related to human safety and environment and a challenging context, call for a strengthening of the maritime preparedness system, and cross-boundary and cross-institutional co......Growing maritime commercial activities in the High North increase the possibility of unwanted incidents. The vulnerability related to human safety and environment and a challenging context, call for a strengthening of the maritime preparedness system, and cross-boundary and cross......-institutional collaboration. In this paper, we look into the different stressors and risk factors of the sea regions in the High North. We elaborate on emergencies where integrated operations such as mass evacuation, oil spill recovery and salvage are needed. Coordination of such operations is a challenging task, where...

  4. The Maritime Cultural Landscape of Northern Patagonia

    Science.gov (United States)

    Lira, Nicolás

    2017-12-01

    This article is a contribution to the study of the indigenous navigation and its boats in the region of northern Patagonia. This article also aims to contribute to the understanding of indigenous navigation practices and technologies and their origins from prehistoric times to the mid-twentieth century. It presents and discusses the concept of Westerdahl's Maritime Cultural Landscape in relation to other landscape concepts. This model is applied to northern Patagonia in order to discuss if it is possible to speak of a true maritime culture in the region. For this purpose, archaeological, historical and ethnographic data are presented in an integrative and innovative methodology for the discipline. Finally, the Maritime Cultural Landscape model will allow the integration of aquatic and terrestrial landscapes as routes traveled by native inhabitants of northern Patagonia and southern Chile, and propose an important and diversified maritime, river and lake tradition.

  5. The New Barbary Wars: Forecasting Maritime Piracy

    NARCIS (Netherlands)

    Daxecker, U.E.; Prins, B.C.

    2015-01-01

    This paper extends systematic analyses of maritime piracy by verifying the robustness of empirical results and examining the forecasting ability of empirical models. Recent research by Ward, Greenhill and Bakke (2010) finds that statistically significant relationships frequently offer poor guidance

  6. Maritime Governance and Policy-Making

    CERN Document Server

    Roe, Michael

    2013-01-01

    A close analysis of the framework of existing governance and the existing jurisdictional arrangements for shipping and ports reveals that while policy-making is characterized by national considerations through flags, institutional representation at all jurisdictions and the inviolability of the state, the commercial, financial, legal and operational environment of the sector is almost wholly global. This governance mismatch means that in practice the maritime industry can avoid policies which it dislikes by trading nations off against one another, while enjoying the freedoms and benefits of a globalized economy. A Post-modern interpretation of this globalized society prompts suggestions for change in maritime policy-making so that the governance of the sector better matches more closely the environment in which shipping and ports operate. Maritime Governance and Policy-Making is a controversial commentary on the record of policy-making in the maritime sector and assesses whether the reason for continued polic...

  7. Regional Maritime University Journal - Vol 1 (2011)

    African Journals Online (AJOL)

    Human errors and system variability in safety investigations of maritime casualties: an expression of systemic concerns · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. KT Ghirxi, 10-22 ...

  8. Maritime archaeology of Lakshadweep Islands, India

    Digital Repository Service at National Institute of Oceanography (India)

    Tripati, S.; Gaur, A.S.; Sundaresh; Vora, K.H.

    route from Europe to Asia before the opening of the Suez Canal In order to delineate the earliest human habitation and maritime contacts of Lakshadweep Islands, archaeological explorations was carried on by the Archaeological Survey of India (ASI...

  9. Maritime archaeology of the Okhamandal region, Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Sundaresh; Gaur, A.S.; Tripati, S.

    to confirm that Okha mandal was a well established industrial place with a flourishing harbour at Bet Dwarka which was having international contacts and must have played critical role in developing the region with the maritime connection....

  10. Physically realistic modeling of maritime training simulation

    OpenAIRE

    Cieutat , Jean-Marc

    2003-01-01

    Maritime training simulation is an important matter of maritime teaching, which requires a lot of scientific and technical skills.In this framework, where the real time constraint has to be maintained, all physical phenomena cannot be studied; the most visual physical phenomena relating to the natural elements and the ship behaviour are reproduced only. Our swell model, based on a surface wave simulation approach, permits to simulate the shape and the propagation of a regular train of waves f...

  11. Quantifying Diurnal Cloud Radiative Effects by Cloud Type in the Tropical Western Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Burleyson, Casey D.; Long, Charles N.; Comstock, Jennifer M.

    2015-06-01

    Cloud radiative effects are examined using long-term datasets collected at the three Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facilities in the tropical western Pacific. We quantify the surface radiation budget, cloud populations, and cloud radiative effects by partitioning the data by cloud type, time of day, and as a function of large scale modes of variability such as El Niño Southern Oscillation (ENSO) phase and wet/dry seasons at Darwin. The novel facet of our analysis is that we break aggregate cloud radiative effects down by cloud type across the diurnal cycle. The Nauru cloud populations and subsequently the surface radiation budget are strongly impacted by ENSO variability whereas the cloud populations over Manus only shift slightly in response to changes in ENSO phase. The Darwin site exhibits large seasonal monsoon related variations. We show that while deeper convective clouds have a strong conditional influence on the radiation reaching the surface, their limited frequency reduces their aggregate radiative impact. The largest source of shortwave cloud radiative effects at all three sites comes from low clouds. We use the observations to demonstrate that potential model biases in the amplitude of the diurnal cycle and mean cloud frequency would lead to larger errors in the surface energy budget compared to biases in the timing of the diurnal cycle of cloud frequency. Our results provide solid benchmarks to evaluate model simulations of cloud radiative effects in the tropics.

  12. Information Services of Maritime Industry

    Science.gov (United States)

    Palazov, Atanas; Stefanov, Asen

    2015-04-01

    The ultimate goal of modern oceanography is an end user oriented product. Beneficiaries are the governmental services, coast-based enterprises and research institutions that make use of the products generated by operational oceanography. Direct potential users and customers are coastal managers, shipping, offshore industry, ports and harbours, fishing, tourism and recreation industry, and scientific community. Indirect beneficiaries, through climate forecasting based on ocean observations, are food, energy, water and medical suppliers. Five general classes of users for data and information are specified: (1) operational users that analyze the collected data and produce different forecasts serving to impose regulation measures; (2) authorities and managers of large-scale projects needing timely oceanographic information, including statistics and climatic trends; (3) industrial enterprises, safety of structures and avoiding of pollution; (4) tourism and recreation related users aiming protection of human health; (5) scientists, engineers, and economists carrying out special researches, strategic design studies, and other investigations to advance the application of marine data. The analysis of information received during the extensive inquiry among all potential end users reveals variety of data and information needs encompassing physical, chemical, biological and hydrometeorological observation. Nevertheless, the common requirement concerns development of observing and forecasting systems providing accurate real-time or near-real time data and information supporting decision making and environmental management. Availability of updated information on the actual state as well as forecast for the future changes of marine environment are essential for the success and safety of maritime operations in the offshore industry. For this purpose different systems have been developed to collect data and to produce forecasts on the state of the marine environment and to provide

  13. Urban effects of Chennai on sea breeze induced convection and ...

    Indian Academy of Sciences (India)

    gate the influence of Chennai urban land use on sea breeze initiated convection and precipitation. ... The larger surface temperature gradient along the coast due to urban effects increased onshore flow by 4.0m s. −1 ... Observational and modeling studies show the .... Explicit equations for cloud water, rainwater, ice.

  14. The sensitivity of Alpine summer convection to surrogate climate change: an intercomparison between convection-parameterizing and convection-resolving models

    Directory of Open Access Journals (Sweden)

    M. Keller

    2018-04-01

    Full Text Available Climate models project an increase in heavy precipitation events in response to greenhouse gas forcing. Important elements of such events are rain showers and thunderstorms, which are poorly represented in models with parameterized convection. In this study, simulations with 12 km horizontal grid spacing (convection-parameterizing model, CPM and 2 km grid spacing (convection-resolving model, CRM are employed to investigate the change in the diurnal cycle of convection with warmer climate. For this purpose, simulations of 11 days in June 2007 with a pronounced diurnal cycle of convection are compared with surrogate simulations from the same period. The surrogate climate simulations mimic a future climate with increased temperatures but unchanged relative humidity and similar synoptic-scale circulation. Two temperature scenarios are compared: one with homogeneous warming (HW using a vertically uniform warming and the other with vertically dependent warming (VW that enables changes in lapse rate.The two sets of simulations with parameterized and explicit convection exhibit substantial differences, some of which are well known from the literature. These include differences in the timing and amplitude of the diurnal cycle of convection, and the frequency of precipitation with low intensities. The response to climate change is much less studied. We can show that stratification changes have a strong influence on the changes in convection. Precipitation is strongly increasing for HW but decreasing for the VW simulations. For cloud type frequencies, virtually no changes are found for HW, but a substantial reduction in high clouds is found for VW. Further, we can show that the climate change signal strongly depends upon the horizontal resolution. In particular, significant differences between CPM and CRM are found in terms of the radiative feedbacks, with CRM exhibiting a stronger negative feedback in the top-of-the-atmosphere energy budget.

  15. The sensitivity of Alpine summer convection to surrogate climate change: an intercomparison between convection-parameterizing and convection-resolving models

    Science.gov (United States)

    Keller, Michael; Kröner, Nico; Fuhrer, Oliver; Lüthi, Daniel; Schmidli, Juerg; Stengel, Martin; Stöckli, Reto; Schär, Christoph

    2018-04-01

    Climate models project an increase in heavy precipitation events in response to greenhouse gas forcing. Important elements of such events are rain showers and thunderstorms, which are poorly represented in models with parameterized convection. In this study, simulations with 12 km horizontal grid spacing (convection-parameterizing model, CPM) and 2 km grid spacing (convection-resolving model, CRM) are employed to investigate the change in the diurnal cycle of convection with warmer climate. For this purpose, simulations of 11 days in June 2007 with a pronounced diurnal cycle of convection are compared with surrogate simulations from the same period. The surrogate climate simulations mimic a future climate with increased temperatures but unchanged relative humidity and similar synoptic-scale circulation. Two temperature scenarios are compared: one with homogeneous warming (HW) using a vertically uniform warming and the other with vertically dependent warming (VW) that enables changes in lapse rate. The two sets of simulations with parameterized and explicit convection exhibit substantial differences, some of which are well known from the literature. These include differences in the timing and amplitude of the diurnal cycle of convection, and the frequency of precipitation with low intensities. The response to climate change is much less studied. We can show that stratification changes have a strong influence on the changes in convection. Precipitation is strongly increasing for HW but decreasing for the VW simulations. For cloud type frequencies, virtually no changes are found for HW, but a substantial reduction in high clouds is found for VW. Further, we can show that the climate change signal strongly depends upon the horizontal resolution. In particular, significant differences between CPM and CRM are found in terms of the radiative feedbacks, with CRM exhibiting a stronger negative feedback in the top-of-the-atmosphere energy budget.

  16. Development of a parameterization scheme of mesoscale convective systems

    International Nuclear Information System (INIS)

    Cotton, W.R.

    1994-01-01

    The goal of this research is to develop a parameterization scheme of mesoscale convective systems (MCS) including diabatic heating, moisture and momentum transports, cloud formation, and precipitation. The approach is to: Perform explicit cloud-resolving simulation of MCSs; Perform statistical analyses of simulated MCSs to assist in fabricating a parameterization, calibrating coefficients, etc.; Test the parameterization scheme against independent field data measurements and in numerical weather prediction (NWP) models emulating general circulation model (GCM) grid resolution. Thus far we have formulated, calibrated, implemented and tested a deep convective engine against explicit Florida sea breeze convection and in coarse-grid regional simulations of mid-latitude and tropical MCSs. Several explicit simulations of MCSs have been completed, and several other are in progress. Analysis code is being written and run on the explicitly simulated data

  17. Wavelet Scale Analysis of Mesoscale Convective Systems for Detecting Deep Convection From Infrared Imagery

    Science.gov (United States)

    Klein, Cornelia; Belušić, Danijel; Taylor, Christopher M.

    2018-03-01

    Mesoscale convective systems (MCSs) are frequently associated with rainfall extremes and are expected to further intensify under global warming. However, despite the significant impact of such extreme events, the dominant processes favoring their occurrence are still under debate. Meteosat geostationary satellites provide unique long-term subhourly records of cloud top temperatures, allowing to track changes in MCS structures that could be linked to rainfall intensification. Focusing on West Africa, we show that Meteosat cloud top temperatures are a useful proxy for rainfall intensities, as derived from snapshots from the Tropical Rainfall Measuring Mission 2A25 product: MCSs larger than 15,000 km2 at a temperature threshold of -40°C are found to produce 91% of all extreme rainfall occurrences in the study region, with 80% of the storms producing extreme rain when their minimum temperature drops below -80°C. Furthermore, we present a new method based on 2-D continuous wavelet transform to explore the relationship between cloud top temperature and rainfall intensity for subcloud features at different length scales. The method shows great potential for separating convective and stratiform cloud parts when combining information on temperature and scale, improving the common approach of using a temperature threshold only. We find that below -80°C, every fifth pixel is associated with deep convection. This frequency is doubled when looking at subcloud features smaller than 35 km. Scale analysis of subcloud features can thus help to better exploit cloud top temperature data sets, which provide much more spatiotemporal detail of MCS characteristics than available rainfall data sets alone.

  18. Genomic selection in maritime pine.

    Science.gov (United States)

    Isik, Fikret; Bartholomé, Jérôme; Farjat, Alfredo; Chancerel, Emilie; Raffin, Annie; Sanchez, Leopoldo; Plomion, Christophe; Bouffier, Laurent

    2016-01-01

    A two-generation maritime pine (Pinus pinaster Ait.) breeding population (n=661) was genotyped using 2500 SNP markers. The extent of linkage disequilibrium and utility of genomic selection for growth and stem straightness improvement were investigated. The overall intra-chromosomal linkage disequilibrium was r(2)=0.01. Linkage disequilibrium corrected for genomic relationships derived from markers was smaller (rV(2)=0.006). Genomic BLUP, Bayesian ridge regression and Bayesian LASSO regression statistical models were used to obtain genomic estimated breeding values. Two validation methods (random sampling 50% of the population and 10% of the progeny generation as validation sets) were used with 100 replications. The average predictive ability across statistical models and validation methods was about 0.49 for stem sweep, and 0.47 and 0.43 for total height and tree diameter, respectively. The sensitivity analysis suggested that prior densities (variance explained by markers) had little or no discernible effect on posterior means (residual variance) in Bayesian prediction models. Sampling from the progeny generation for model validation increased the predictive ability of markers for tree diameter and stem sweep but not for total height. The results are promising despite low linkage disequilibrium and low marker coverage of the genome (∼1.39 markers/cM). Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  19. Maritime Fuel Cell Generator Project.

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Joseph William [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2017-07-01

    Fuel costs and emissions in maritime ports are an opportunity for transportation energy efficiency improvement and emissions reduction efforts. Ocean-going vessels, harbor craft, and cargo handling equipment are still major contributors to air pollution in and around ports. Diesel engine costs continually increase as tighter criteria pollutant regulations come into effect and will continue to do so with expected introduction of carbon emission regulations. Diesel fuel costs will also continue to rise as requirements for cleaner fuels are imposed. Both aspects will increase the cost of diesel-based power generation on the vessel and on shore. Although fuel cells have been used in many successful applications, they have not been technically or commercially validated in the port environment. One opportunity to do so was identified in Honolulu Harbor at the Young Brothers Ltd. wharf. At this facility, barges sail regularly to and from neighbor islands and containerized diesel generators provide power for the reefers while on the dock and on the barge during transport, nearly always at part load. Due to inherent efficiency characteristics of fuel cells and diesel generators, switching to a hydrogen fuel cell power generator was found to have potential emissions and cost savings.

  20. Testing particle filters on convective scale dynamics

    Science.gov (United States)

    Haslehner, Mylene; Craig, George. C.; Janjic, Tijana

    2014-05-01

    Particle filters have been developed in recent years to deal with highly nonlinear dynamics and non Gaussian error statistics that also characterize data assimilation on convective scales. In this work we explore the use of the efficient particle filter (P.v. Leeuwen, 2011) for convective scale data assimilation application. The method is tested in idealized setting, on two stochastic models. The models were designed to reproduce some of the properties of convection, for example the rapid development and decay of convective clouds. The first model is a simple one-dimensional, discrete state birth-death model of clouds (Craig and Würsch, 2012). For this model, the efficient particle filter that includes nudging the variables shows significant improvement compared to Ensemble Kalman Filter and Sequential Importance Resampling (SIR) particle filter. The success of the combination of nudging and resampling, measured as RMS error with respect to the 'true state', is proportional to the nudging intensity. Significantly, even a very weak nudging intensity brings notable improvement over SIR. The second model is a modified version of a stochastic shallow water model (Würsch and Craig 2013), which contains more realistic dynamical characteristics of convective scale phenomena. Using the efficient particle filter and different combination of observations of the three field variables (wind, water 'height' and rain) allows the particle filter to be evaluated in comparison to a regime where only nudging is used. Sensitivity to the properties of the model error covariance is also considered. Finally, criteria are identified under which the efficient particle filter outperforms nudging alone. References: Craig, G. C. and M. Würsch, 2012: The impact of localization and observation averaging for convective-scale data assimilation in a simple stochastic model. Q. J. R. Meteorol. Soc.,139, 515-523. Van Leeuwen, P. J., 2011: Efficient non-linear data assimilation in geophysical

  1. Satellite retrieval of cloud condensation nuclei concentrations by using clouds as CCN chambers

    Science.gov (United States)

    Rosenfeld, Daniel; Zheng, Youtong; Hashimshoni, Eyal; Pöhlker, Mira L.; Jefferson, Anne; Pöhlker, Christopher; Yu, Xing; Zhu, Yannian; Liu, Guihua; Yue, Zhiguo; Fischman, Baruch; Li, Zhanqing; Giguzin, David; Goren, Tom; Artaxo, Paulo; Pöschl, Ulrich

    2016-01-01

    Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Validation against ground-based CCN instruments at Oklahoma, at Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25° restricts the satellite coverage to ∼25% of the world area in a single day. PMID:26944081

  2. Cloud Governance

    DEFF Research Database (Denmark)

    Berthing, Hans Henrik

    Denne præsentation beskriver fordele og værdier ved anvendelse af Cloud Computing. Endvidere inddrager resultater fra en række internationale analyser fra ISACA om Cloud Computing.......Denne præsentation beskriver fordele og værdier ved anvendelse af Cloud Computing. Endvidere inddrager resultater fra en række internationale analyser fra ISACA om Cloud Computing....

  3. The Development of Geo-KOMPSAT-2A (GK-2A) Convective Initiation Algorithm over the Korea peninsular

    Science.gov (United States)

    Kim, H. S.; Chung, S. R.; Lee, B. I.; Baek, S.; Jeon, E.

    2016-12-01

    The rapid development of convection can bring heavy rainfall that suffers a great deal of damages to society as well as threatens human life. The high accurate forecast of the strong convection is essentially demanded to prevent those disasters from the severe weather. Since a geostationary satellite is the most suitable instrument for monitoring the single cloud's lifecycle from its formation to extinction, it has been attempted to capture the precursor signals of convection clouds by satellite. Keeping pace with the launch of Geo-KOMPSAT-2A (GK-2A) in 2018, we planned to produce convective initiation (CI) defined as the indicator of potential cloud objects to bring heavy precipitation within two hours. The CI algorithm for GK-2A is composed of four stages. The beginning is to subtract mature cloud pixels, a sort of convective cloud mask by visible (VIS) albedo and infrared (IR) brightness temperature thresholds. Then, the remained immature cloud pixels are clustered as a cloud object by watershed techniques. Each clustering object is undergone 'Interest Fields' tests for IR data that reflect cloud microphysical properties at the current and their temporal changes; the cloud depth, updraft strength and production of glaciations. All thresholds of 'Interest fields' were optimized for Korean-type convective clouds. Based on scores from tests, it is decided whether the cloud object would develop as a convective cell or not. Here we show the result of case study in this summer over the Korea peninsular by using Himawari-8 VIS and IR data. Radar echo and data were used for validation. This study suggests that CI products of GK-2A would contribute to enhance accuracy of the very short range forecast over the Korea peninsular.

  4. Observing Convective Aggregation

    Science.gov (United States)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-11-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  5. A-Train Observations of Deep Convective Storm Tops

    Science.gov (United States)

    Setvak, Martin; Bedka, Kristopher; Lindsey, Daniel T.; Sokol, Alois; Charvat, Zdenek; Stastka, Jindrich; Wang, Pao K.

    2013-01-01

    The paper highlights simultaneous observations of tops of deep convective clouds from several space-borne instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS) of the Aqua satellite, Cloud Profiling Radar (CPR) of the CloudSat satellite, and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) flown on the CALIPSO satellite. These satellites share very close orbits, thus together with several other satellites they are referred to as the "A-Train" constellation. Though the primary responsibility of these satellites and their instrumentation is much broader than observations of fine-scale processes atop convective storms, in this study we document how data from the A-Train can contribute to a better understanding and interpretation of various storm-top features, such as overshooting tops, cold-U/V and cold ring features with their coupled embedded warm areas, above anvil ice plumes and jumping cirrus. The relationships between MODIS multi-spectral brightness temperature difference (BTD) fields and cloud top signatures observed by the CPR and CALIOP are also examined in detail to highlight the variability in BTD signals across convective storm events.

  6. Maritime zones delimitation - Problems and solutions

    Science.gov (United States)

    Kastrisios, Christos; Tsoulos, Lysandros

    2018-05-01

    The delimitation of maritime zones and boundaries foreseen by the United Nations Convention on the Law of the Sea (UNCLOS) is a factor of economic growth, effective management of the coastal and ocean environment and the cornerstone for maritime spatial planning. Maritime zones and boundaries form the outermost limits of coastal states and their accurate delineation and cartographic portrayal is a matter of national priority. Although UNCLOS is a legal document, its implementation -at first place- is purely technical and requires -amongst others- theoretical and applied background on Geodesy, Cartography and Geographic Information Systems (GIS) for those involved. This paper provides a brief historical background of the evolution of the UNCLOS, presents the various concepts of the Convention and identifies the problems inherent in the maritime delimitation process. Furthermore, it presents solutions that will facilitate the cartographer's work in order to achieve unquestionable results. Through the paper it becomes evident that the role of the cartographer and the GIS expert is critical for the successful implementation of maritime delimitation.

  7. Orchestrating Transnational Environmental Governance in Maritime Shipping

    DEFF Research Database (Denmark)

    Lister, Jane; Taudal Poulsen, René; Ponte, Stefano

    2015-01-01

    Maritime shipping is the transmission belt of the global economy. It is also a major contributor to global environmental change through its under-regulated air, water and land impacts. It is puzzling that shipping is a lagging sector as it has a well-established global regulatory body—the Interna......Maritime shipping is the transmission belt of the global economy. It is also a major contributor to global environmental change through its under-regulated air, water and land impacts. It is puzzling that shipping is a lagging sector as it has a well-established global regulatory body......—the International Maritime Organization. Drawing on original empirical evidence and archival data, we introduce a four-factor framework to investigate two main questions: why is shipping lagging in its environmental governance; and what is the potential for the International Maritime Organization to orchestrate......, and growing regulatory fragmentation and uncertainty. The paper concludes with pragmatic recommendations for the International Maritime Organization to acknowledge the regulatory difficulties and seize the opportunity to orchestrate environmental progress....

  8. Multi-scale Modeling of Arctic Clouds

    Science.gov (United States)

    Hillman, B. R.; Roesler, E. L.; Dexheimer, D.

    2017-12-01

    The presence and properties of clouds are critically important to the radiative budget in the Arctic, but clouds are notoriously difficult to represent in global climate models (GCMs). The challenge stems partly from a disconnect in the scales at which these models are formulated and the scale of the physical processes important to the formation of clouds (e.g., convection and turbulence). Because of this, these processes are parameterized in large-scale models. Over the past decades, new approaches have been explored in which a cloud system resolving model (CSRM), or in the extreme a large eddy simulation (LES), is embedded into each gridcell of a traditional GCM to replace the cloud and convective parameterizations to explicitly simulate more of these important processes. This approach is attractive in that it allows for more explicit simulation of small-scale processes while also allowing for interaction between the small and large-scale processes. The goal of this study is to quantify the performance of this framework in simulating Arctic clouds relative to a traditional global model, and to explore the limitations of such a framework using coordinated high-resolution (eddy-resolving) simulations. Simulations from the global model are compared with satellite retrievals of cloud fraction partioned by cloud phase from CALIPSO, and limited-area LES simulations are compared with ground-based and tethered-balloon measurements from the ARM Barrow and Oliktok Point measurement facilities.

  9. Origin of the pre-tropical storm Debby (2006) African easterly wave-mesoscale convective system

    Science.gov (United States)

    Lin, Yuh-Lang; Liu, Liping; Tang, Guoqing; Spinks, James; Jones, Wilson

    2013-05-01

    The origins of the pre-Debby (2006) mesoscale convective system (MCS) and African easterly wave (AEW) and their precursors were traced back to the southwest Arabian Peninsula, Asir Mountains (AS), and Ethiopian Highlands (EH) in the vicinity of the ITCZ using satellite imagery, GFS analysis data and ARW model. The sources of the convective cloud clusters and vorticity perturbations were attributed to the cyclonic convergence of northeasterly Shamal wind and the Somali jet, especially when the Mediterranean High shifted toward east and the Indian Ocean high strengthened and its associated Somali jet penetrated farther to the north. The cyclonic vorticity perturbations were strengthened by the vorticity stretching associated with convective cloud clusters in the genesis region—southwest Arabian Peninsula. A conceptual model was proposed to explain the genesis of convective cloud clusters and cyclonic vorticity perturbations preceding the pre-Debby (2006) AEW-MCS system.

  10. 78 FR 42101 - Boston Area Maritime Security Advisory Committee; Vacancies

    Science.gov (United States)

    2013-07-15

    ... the Captain of the Port in the development, review, update, and exercising of the Area Maritime..., including labor; other port stakeholders having a special competence in maritime security; and port...

  11. Maritime oil freight flows to 2050: Delphi perceptions of maritime specialists

    International Nuclear Information System (INIS)

    Dinwoodie, John; Tuck, Sarah; Rigot-Müller, Patrick

    2013-01-01

    This paper aims to synthesise maritime specialists' perceptions of changing patterns of maritime oil freight flows to 2050. Debate spans published maritime oil flows globally, diverse drivers of future flows including economic growth, shipping market changes and haul lengths. A classic Delphi study to explore the perceptions of likely trends and flows to 2050 recruited a panel of early career and established maritime specialists, many with long term career commitments to this industry. Underpinned by market volatility and legislative uncertainty, the perceptions of both groups coincided and were conservative. Local sourcing, new Arctic seaways and fossil fuel intolerance will tend to reduce oil freight work but perceptions of ship re-routing to avoid for example Emission Control Areas and piracy would tend to lengthen hauls. In advanced industrial nations, reducing energy intensities and diminishing social tolerance of fossil fuels imply gradually reducing maritime oil shipments. However, to achieve radical national commitments to carbon emissions reductions will necessitate specialist education for naturally conservative maritime professionals and vigorous oil import reduction policies to curtail domestic demand for oil shipments. - Highlights: • Local sourcing, Arctic seaways and fossil fuel intolerance lessen oil freight work. • Oil hauls lengthen if ships re-route to avoid Emission Control Areas and piracy. • Conservative perceptions of established specialists match early career views. • Carbon emission reduction policies imply significantly reduced oil shipments. • Attitude change in maritime professionals will require education and marketing

  12. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Directory of Open Access Journals (Sweden)

    M. Bolot

    2013-08-01

    Full Text Available The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process. As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  13. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Science.gov (United States)

    Bolot, M.; Legras, B.; Moyer, E. J.

    2013-08-01

    The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener-Bergeron-Findeisen process). As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  14. Modelling and intepreting the isotopic composition of water vapour in convective updrafts

    Science.gov (United States)

    Bolot, M.; Legras, B.; Moyer, E. J.

    2012-08-01

    The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener-Bergeron-Findeisen process). As all of these processes are related to updraft strength, droplet size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  15. Convective heat transfer

    CERN Document Server

    Kakac, Sadik; Pramuanjaroenkij, Anchasa

    2014-01-01

    Intended for readers who have taken a basic heat transfer course and have a basic knowledge of thermodynamics, heat transfer, fluid mechanics, and differential equations, Convective Heat Transfer, Third Edition provides an overview of phenomenological convective heat transfer. This book combines applications of engineering with the basic concepts of convection. It offers a clear and balanced presentation of essential topics using both traditional and numerical methods. The text addresses emerging science and technology matters, and highlights biomedical applications and energy technologies. What’s New in the Third Edition: Includes updated chapters and two new chapters on heat transfer in microchannels and heat transfer with nanofluids Expands problem sets and introduces new correlations and solved examples Provides more coverage of numerical/computer methods The third edition details the new research areas of heat transfer in microchannels and the enhancement of convective heat transfer with nanofluids....

  16. Maritime governance speed, flow, form process

    CERN Document Server

    Roe, Michael

    2016-01-01

    This book provides an original analysis of the problems facing global governance and in particular that of one of the most globalised of all industries – shipping. Central to all global trade and its dramatic growth, shipping faces difficulties of governance stemming from its every globalised nature. The current characteristics of global governance – nation-state fixation, anachronistic institutions, inadequate stakeholder involvement and an over-domination of owner interests are dwarfed by the problems of stasis and fixation which means that policies to address problems of safety, the environment and security are inadequate. This book provides a full and wide ranging discussion of how governance can be animated in a global context so that the dynamism of the maritime industry and its problems can be prevented, regulated and understood. Its unique approach to governance makes it essential reading for all maritime policy-makers and those analysing maritime issues, alongside those with an interest in govern...

  17. Liability in maritime transport of dangerous goods

    International Nuclear Information System (INIS)

    Feldhaus, H.

    1985-01-01

    The first part contains a description of national liability standards for maritime transport in the French, English, US-American and West German legislation. This is followed up by a detailed review of the existing international agreements. The book is rounded off by a critical evaluation of the presently held discussion and suggested solutions on the problems of liability in the maritime transport of dangerous goods other than mineral oil. The author takes a close look at the 'Entwurf eines Internationalen Uebereinkommens ueber die Haftung und den Schadenersatz bei der Befoerderung schaedlicher und gefaehrlicher Stoffe auf See' ('draft of an international agreement on liability and compensation for damage in maritime transport of noxious and dangerous goods') in the version of May 23, 1983, which was discussed on an international diplomat's conference in London without however, yielding any concrete results. (orig./HP) [de

  18. 31 CFR 538.519 - Aircraft and maritime safety.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Aircraft and maritime safety. 538.519..., Authorizations, and Statements of Licensing Policy § 538.519 Aircraft and maritime safety. Specific licenses may... aircraft, and to ensure the safety of ocean-going maritime traffic in international waters. ...

  19. 29 CFR 2530.200b-6 - Maritime industry.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Maritime industry. 2530.200b-6 Section 2530.200b-6 Labor... Provisions § 2530.200b-6 Maritime industry. (a) General. Sections 202(a)(3)(D), 203(b)(2)(D) and 204(b)(3)(E... provisions applicable to the maritime industry. In general, those provisions permit statutory standards...

  20. 33 CFR 106.140 - Maritime Security (MARSEC) Directive.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maritime Security (MARSEC... SECURITY MARITIME SECURITY MARINE SECURITY: OUTER CONTINENTAL SHELF (OCS) FACILITIES General § 106.140 Maritime Security (MARSEC) Directive. All OCS facility owners or operators subject to this part must comply...

  1. 32 CFR 536.124 - Settlement authority for maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Settlement authority for maritime claims. 536.124 Section 536.124 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Maritime Claims § 536.124 Settlement authority for maritime...

  2. 46 CFR 5.71 - Maritime labor disputes.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Maritime labor disputes. 5.71 Section 5.71 Shipping... REGULATIONS-PERSONNEL ACTION Statement of Policy and Interpretation § 5.71 Maritime labor disputes. Under no circumstances will the Coast Guard exercise its authority for the purpose of favoring any party to a maritime...

  3. 47 CFR 80.389 - Frequencies for maritime support stations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for maritime support stations. 80.389 Section 80.389 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Maritime Support Stations § 80.389...

  4. Extended-range prediction trials using the global cloud/cloud-system resolving model NICAM and its new ocean-coupled version NICOCO

    Science.gov (United States)

    Miyakawa, Tomoki

    2017-04-01

    The global cloud/cloud-system resolving model NICAM and its new fully-coupled version NICOCO is run on one of the worlds top-tier supercomputers, the K computer. NICOCO couples the full-3D ocean component COCO of the general circulation model MIROC using a general-purpose coupler Jcup. We carried out multiple MJO simulations using NICAM and the new ocean-coupled version NICOCO to examine their extended-range MJO prediction skills and the impact of ocean coupling. NICAM performs excellently in terms of MJO prediction, maintaining a valid skill up to 27 days after the model is initialized (Miyakawa et al 2014). As is the case in most global models, ocean coupling frees the model from being anchored by the observed SST and allows the model climate to drift away further from reality compared to the atmospheric version of the model. Thus, it is important to evaluate the model bias, and in an initial value problem such as the seasonal extended-range prediction, it is essential to be able to distinguish the actual signal from the early transition of the model from the observed state to its own climatology. Since NICAM is a highly resource-demanding model, evaluation and tuning of the model climatology (order of years) is challenging. Here we focus on the initial 100 days to estimate the early drift of the model, and subsequently evaluate MJO prediction skills of NICOCO. Results show that in the initial 100 days, NICOCO forms a La-Nina like SST bias compared to observation, with a warmer Maritime Continent warm pool and a cooler equatorial central Pacific. The enhanced convection over the Maritime Continent associated with this bias project on to the real-time multi-variate MJO indices (RMM, Wheeler and Hendon 2004), and contaminates the MJO skill score. However, the bias does not appear to demolish the MJO signal severely. The model maintains a valid MJO prediction skill up to nearly 4 weeks when evaluated after linearly removing the early drift component estimated from

  5. Near-equatorial convective regimes over the Indian Ocean as revealed by synergistic analysis of satellite observations.

    Digital Repository Service at National Institute of Oceanography (India)

    Levy, G.; Geiss, A.; RameshKumar, M.R.

    We examine the organization and temporal evolution of deep convection in relation to the low level flow over the Indian Ocean by a synergistic analysis of several satellite datasets for wind, rainfall, Outgoing Longwave Radiation (OLR) and cloud...

  6. Impact of deforestation in the Amazon basin on cloud climatology.

    Science.gov (United States)

    Wang, Jingfeng; Chagnon, Frédéric J F; Williams, Earle R; Betts, Alan K; Renno, Nilton O; Machado, Luiz A T; Bisht, Gautam; Knox, Ryan; Bras, Rafael L

    2009-03-10

    Shallow clouds are prone to appear over deforested surfaces whereas deep clouds, much less frequent than shallow clouds, favor forested surfaces. Simultaneous atmospheric soundings at forest and pasture sites during the Rondonian Boundary Layer Experiment (RBLE-3) elucidate the physical mechanisms responsible for the observed correlation between clouds and land cover. We demonstrate that the atmospheric boundary layer over the forested areas is more unstable and characterized by larger values of the convective available potential energy (CAPE) due to greater humidity than that which is found over the deforested area. The shallow convection over the deforested areas is relatively more active than the deep convection over the forested areas. This greater activity results from a stronger lifting mechanism caused by mesoscale circulations driven by deforestation-induced heterogeneities in land cover.

  7. Tropical cloud buoyancy is the same in a world with or without ice

    Science.gov (United States)

    Seeley, Jacob T.; Romps, David M.

    2016-04-01

    When convective clouds grow above the melting line, where temperatures fall below 0°C, condensed water begins to freeze and water vapor is deposited. These processes release the latent heat of fusion, which warms cloud air, and many previous studies have suggested that this heating from fusion increases cloud buoyancy in the upper troposphere. Here we use numerical simulations of radiative-convective equilibrium with and without ice processes to argue that tropical cloud buoyancy is not systematically higher in a world with fusion than in a world without it. This insensitivity results from the fact that the environmental temperature profile encountered by developing tropical clouds is itself determined by convection. We also offer a simple explanation for the large reservoir of convective available potential energy in the tropical upper troposphere that does not invoke ice.

  8. Cloud-to-ground lightning over Mexico and adjacent oceanic regions. A preliminary climatology using the WWLLN dataset

    Energy Technology Data Exchange (ETDEWEB)

    Kucienska, B.; Raga, G.B. [Universidad Nacional Autonoma de Mexico (Mexico). Centro de Ciencias de la Atmosfera; Rodriguez, O. [Instituto Mexicano de Tecnologia del Agua, Morelos (Mexico)

    2010-07-01

    This work constitutes the first climatological study of lightning over Mexico and adjacent oceanic areas for the period 2005-2009. Spatial and temporal distributions of cloud to ground lightning are presented and the processes that contribute to the lightning variability are analysed. The data are retrieved from theWorldWide Lightning Location Network (WWLLN) dataset. The current WWLL network includes 40 stations which cover much of the globe and detect very low frequency radiation (''spherics'') associated with lightning. The spatial distribution of the average yearly lightning over the continental region of Mexico shows the influence of orographic forcing in producing convective clouds with high lightning activity. However, a very high number of strikes is also observed in the States of Tabasco and Campeche, which are low-lying areas. This maximum is related to the climatological maximum of precipitation for the country and it may be associated with a region of persistent low-level convergence and convection in the southern portion of the Gulf of Mexico. The maps of correlation between rainfall and lightning provide insight into the microphysical processes occurring within the clouds. The maritime clouds close to the coastline exhibit similar properties to continental clouds as they produce very high lightning activity. The seasonal cycle of lightning registered by WWLLN is consistent with the LIS/OTD dataset for the selected regions. In terms of the annual distribution of cloud-to-ground strikes, July, August and September exhibit the highest number of strikes over continental Mexico. The diurnal cycle indicates that the maximum number of strikes over the continent is observed between 6 and 9 p.m. LT. The surrounding oceanic regions were subdivided into four distinct sectors: Gulf of Mexico, Caribbean, Subtropical Pacific and Tropical Pacific. The Gulf of Mexico has the broadest seasonal distribution, since during winter lightning associated

  9. Aerosol and Cloud Microphysical Properties in the Asir region of Saudi Arabia

    Science.gov (United States)

    Axisa, Duncan; Kucera, Paul; Burger, Roelof; Li, Runjun; Collins, Don; Freney, Evelyn; Posada, Rafael; Buseck, Peter

    2010-05-01

    In recent advertent and inadvertent weather modification studies, a considerable effort has been made to understand the impact of varying aerosol properties and concentration on cloud properties. Significant uncertainties exist with aerosol-cloud interactions for which complex microphysical processes link the aerosol and cloud properties. Under almost all environmental conditions, increased aerosol concentrations within polluted air masses will enhance cloud droplet concentration relative to that in unperturbed regions. The interaction between dust particles and clouds are significant, yet the conditions in which dust particles become cloud condensation nuclei (CCN) are uncertain. In order to quantify this aerosol effect on clouds and precipitation, a field campaign was launched in the Asir region of Saudi Arabia as part of a Precipitation Enhancement Feasibility Study. Ground measurements of aerosol size distributions, hygroscopic growth factor, CCN concentrations as well as aircraft measurements of cloud hydrometeor size distributions were done in the Asir region of Saudi Arabia in August 2009. Research aircraft operations focused primarily on conducting measurements in clouds that are targeted for cloud top-seeding, on their microphysical characterization, especially the preconditions necessary for precipitation; understanding the evolution of droplet coalescence, supercooled liquid water, cloud ice and precipitation hydrometeors is necessary if advances are to be made in the study of cloud modification by cloud seeding. Non-precipitating mixed-phase clouds less than 3km in diameter that developed on top of the stable inversion were characterized by flying at the convective cloud top just above the inversion. Aerosol measurements were also done during the climb to cloud base height. The presentation will include a summary of the analysis and results with a focus on the unique features of the Asir region in producing convective clouds, characterization of the

  10. Black carbon semi-direct effects on cloud cover: review and synthesis

    Directory of Open Access Journals (Sweden)

    D. Koch

    2010-08-01

    Full Text Available Absorbing aerosols (AAs such as black carbon (BC or dust absorb incoming solar radiation, perturb the temperature structure of the atmosphere, and influence cloud cover. Previous studies have described conditions under which AAs either increase or decrease cloud cover. The effect depends on several factors, including the altitude of the AA relative to the cloud and the cloud type. We attempt to categorize the effects into several likely regimes. Cloud cover is decreased if the AAs are embedded in the cloud layer. AAs below cloud may enhance convection and cloud cover. AAs above cloud top stabilize the underlying layer and tend to enhance stratocumulus clouds but may reduce cumulus clouds. AAs can also promote cloud cover in convergent regions as they enhance deep convection and low level convergence as it draws in moisture from ocean to land regions. Most global model studies indicate a regional variation in the cloud response but generally increased cloud cover over oceans and some land regions, with net increased low-level and/or reduced upper level cloud cover. The result is a net negative semi-direct effect feedback from the cloud response to AAs. In some of these climate model studies, the cooling effect of BC due to cloud changes is strong enough to essentially cancel the warming direct effects.

  11. Responses of Mean and Extreme Precipitation to Deforestation in the Maritime Continent

    Science.gov (United States)

    Chen, C. C.; Lo, M. H.; Yu, J. Y.

    2017-12-01

    Anthropogenic land use and land cover change, including tropical deforestation, could have substantial effects on local surface energy and water budgets, and thus on the atmospheric stability which may result in changes in precipitation. Maritime Continent has undergone severe deforestation in recent decades but has received less attention than Amazon or Congo rainforests. Therefore, this study is to decipher the precipitation response to deforestation in the Maritime Continent. We conduct deforestation experiments using Community Earth System Model (CESM) and through converting the tropical rainforest into grassland. The results show that deforestation in Maritime Continent leads to an increase in both mean temperature and mean precipitation. Moisture budget analysis indicates that the increase in precipitation is associated with the vertically integrated vertical moisture advection, especially the dynamic component (changes in convection). In addition, through moist static energy (MSE) budget analysis, we find the atmosphere among deforested areas become unstable owing to the combined effects of positive specific humidity anomalies at around 850 hPa and anomalous warming extended from the surface to 750 hPa. This instability will induce anomalous ascending motion, which could enhance the low-level moisture convergence, providing water vapor from the surrounding warm ocean. To further evaluate the precipitation response to deforestation, we examine the precipitation changes under La Niña events and global warming scenario using CESM Atmospheric Model Intercomparison Project (AMIP) simulations and Representative Concentration Pathway (RCP) 8.5 simulations. We find that the precipitation increase caused by deforestation in Maritime Continent is comparable in magnitude to that generated by either natural variability or global warming forcing. Besides the changes in mean precipitation, preliminary results show the extreme precipitation also increases. We will further

  12. The Stochastic Multicloud Model as part of an operational convection parameterisation in a comprehensive GCM

    Science.gov (United States)

    Peters, Karsten; Jakob, Christian; Möbis, Benjamin

    2015-04-01

    An adequate representation of convective processes in numerical models of the atmospheric circulation (general circulation models, GCMs) remains one of the grand challenges in atmospheric science. In particular, the models struggle with correctly representing the spatial distribution and high variability of tropical convection. It is thought that this model deficiency partly results from formulating current convection parameterisation schemes in a purely deterministic manner. Here, we use observations of tropical convection to inform the design of a novel convection parameterisation with stochastic elements. The novel scheme is built around the Stochastic MultiCloud Model (SMCM, Khouider et al 2010). We present the progress made in utilising SMCM-based estimates of updraft area fractions at cloud base as part of the deep convection scheme of a GCM. The updraft area fractions are used to yield one part of the cloud base mass-flux used in the closure assumption of convective mass-flux schemes. The closure thus receives a stochastic component, potentially improving modeled convective variability and coherence. For initial investigations, we apply the above methodology to the operational convective parameterisation of the ECHAM6 GCM. We perform 5-year AMIP simulations, i.e. with prescribed observed SSTs. We find that with the SMCM, convection is weaker and more coherent and continuous from timestep to timestep compared to the standard model. Total global precipitation is reduced in the SMCM run, but this reduces i) the overall error compared to observed global precipitation (GPCP) and ii) middle tropical tropospheric temperature biases compared to ERA-Interim. Hovmoeller diagrams indicate a slightly higher degree of convective organisation compared to the base case and Wheeler-Kiladis frequency wavenumber diagrams indicate slightly more spectral power in the MJO range.

  13. A Task No Maritime Operational Commander Wants: Maritime Interception Operations (MIO) Are Not Going Away

    National Research Council Canada - National Science Library

    Dawley, Sterling

    2003-01-01

    Maritime Interception Operations (MIO) as a mission area for USN and USCG assets does not seem to be going away anytime soon The purpose of this essay is to assess past MIO efforts and offer recommendations to assist the operational...

  14. Cloud Computing

    CERN Document Server

    Antonopoulos, Nick

    2010-01-01

    Cloud computing has recently emerged as a subject of substantial industrial and academic interest, though its meaning and scope is hotly debated. For some researchers, clouds are a natural evolution towards the full commercialisation of grid systems, while others dismiss the term as a mere re-branding of existing pay-per-use technologies. From either perspective, 'cloud' is now the label of choice for accountable pay-per-use access to third party applications and computational resources on a massive scale. Clouds support patterns of less predictable resource use for applications and services a

  15. The safety features of an integrated maritime reactor

    International Nuclear Information System (INIS)

    Miyakoshi, Junichi; Yamada, Nobuyuki; Kuwahara, Shin-ichi

    1975-01-01

    The EFDR-80, a typical integrated maritime reactor, which is being developed in West Germany is outlined. The safety features of the integrated maritime reactor are presented with the analysis of reactor accidents and hazards, and are compared with those of the separated maritime reactor. Furthermore, the safety criteria of maritime reactors in Japan and West Germany are compared, and some of the differences are presented from the viewpoint of reactor design and safety analysis. In this report the authors express an earnest desire that the definite and reasonable safety criteria of the integrated maritime reactor should be established and that the safety criteria of the nuclear ship should be standardized internationally. (auth.)

  16. Maritime environmental penal law. International and German legislation

    International Nuclear Information System (INIS)

    Eller, Jan Frederik

    2017-01-01

    The book on maritime environmental penal law discusses the following issues: part I: introduction into the importance of oceanic environment and its thread, requirement of protective measures,; part II: focus of the study and terminology: oceanic pollution, maritime environmental legislation, international legislation; part 3: international legislative regulations concerning the protection of maritime environment: avoidance of environmental pollution, maritime legislative agreements, existing protective institutions; part 4: state penal power concerning maritime environmental protection; part 5: statutory offense according to German legislation; perspectives for regulations concerning criminal acts on sea.

  17. Comprehensive review of the maritime safety regimes.

    NARCIS (Netherlands)

    S. Knapp (Sabine); Ph.H.B.F. Franses (Philip Hans)

    2007-01-01

    textabstractThis report presents a comprehensive review of the maritime safety regimes and provides recommendations on how to improve the system. The results show a complex legal framework which generates a high amount of inspections and overlapping of inspection areas where no cross-recognition is

  18. Haiyang Qiangguo: China as a Maritime Power

    Science.gov (United States)

    2016-03-15

    solar power from the sea, pharmaceuticals derived from marine animal and plant products, and even maritime tourism .58 To date, most of this activity...the PLAN will need to develop operational units that are better suited for carrying out operations other than war, such as medical units for

  19. A method to assess maritime resilience

    NARCIS (Netherlands)

    Rypkema, J.A.; Beek, F.A. van der; Schraagen, J.M.C.; Winkelman, J.W.; Wijngaarden, M. van

    2015-01-01

    The aim of this study is to develop a multi-level resilience analysis method (RAM) to assess risk and performance variability in current maritime socio-technical systems (STSs). The method integrates Hollnagel’s four resilience abilities to assess a system’s ability to effectively cope with

  20. Opportunities in Marine and Maritime Careers.

    Science.gov (United States)

    Heitzmann, Wm. Ray

    This book describes careers related to the sea. The following chapters are included: (1) "The World of Water"; (2) "Cruise Ship Careers"; (3) "Oceanography and the Marine Sciences"; (4) "Fishing"; (5) "Commerical Diving"; (6) "Maritime Transportation"; (7) "Shipbuilding"; (8) "Military Careers Afloat"; (9) "Miscellaneous Marine and Maritime…

  1. Green maritime transportation: Speed and route optimization

    DEFF Research Database (Denmark)

    Psaraftis, Harilaos N.; Kontovas, Christos A.

    2015-01-01

    Among the spectrum of logistics-based measures for green maritime transportation, this chapter focuses on speed optimization. This involves the selection of an appropriate speed by the vessel, so as to optimize a certain objective. As ship speed is not fixed, depressed shipping markets and/or high...

  2. 76 FR 29989 - National Maritime Day, 2011

    Science.gov (United States)

    2011-05-24

    ... and tugs, in our ports and shipyards, close to home or far at sea, to connect businesses, service members, and citizens around the world. On National Maritime Day, we honor their invaluable contributions... across the world and aiding our military at war. During World War II, Merchant Marines were critical in...

  3. Maritime Load Dependent Lead Times - An Analysis

    DEFF Research Database (Denmark)

    Pahl, Julia; Voss, Stefan

    2017-01-01

    in production. Inspired by supply chain planning systems, we analyze the current state of (collaborative) planning in the maritime transport chain with focus on containers. Regarding the problem of congestion, we particularly emphasize on load dependent lead times (LDLT) which are well studied in production....

  4. Maritime drug interdiction in international law

    NARCIS (Netherlands)

    Kruit, P.J.J. van der

    2007-01-01

    The study focuses on the interdiction of trafficking in illicit drugs at sea as one part of the general problem of illicit drug trafficking. More specifically, the study focuses on the legal framework for the interdiction of illicit maritime drug trafficking under international law. Firstly, the

  5. Upscale Impact of Mesoscale Disturbances of Tropical Convection on Convectively Coupled Kelvin Waves

    Science.gov (United States)

    Yang, Q.; Majda, A.

    2017-12-01

    Tropical convection associated with convectively coupled Kelvin waves (CCKWs) is typically organized by an eastward-moving synoptic-scale convective envelope with numerous embedded westward-moving mesoscale disturbances. It is of central importance to assess upscale impact of mesoscale disturbances on CCKWs as mesoscale disturbances propagate at various tilt angles and speeds. Here a simple multi-scale model is used to capture this multi-scale structure, where mesoscale fluctuations are directly driven by mesoscale heating and synoptic-scale circulation is forced by mean heating and eddy transfer of momentum and temperature. The two-dimensional version of the multi-scale model drives the synoptic-scale circulation, successfully reproduces key features of flow fields with a front-to-rear tilt and compares well with results from a cloud resolving model. In the scenario with an elevated upright mean heating, the tilted vertical structure of synoptic-scale circulation is still induced by the upscale impact of mesoscale disturbances. In a faster propagation scenario, the upscale impact becomes less important, while the synoptic-scale circulation response to mean heating dominates. In the unrealistic scenario with upward/westward tilted mesoscale heating, positive potential temperature anomalies are induced in the leading edge, which will suppress shallow convection in a moist environment. In its three-dimensional version, results show that upscale impact of mesoscale disturbances that propagate at tilt angles (110o 250o) induces negative lower-tropospheric potential temperature anomalies in the leading edge, providing favorable conditions for shallow convection in a moist environment, while the remaining tilt angle cases have opposite effects. Even in the presence of upright mean heating, the front-to-rear tilted synoptic-scale circulation can still be induced by eddy terms at tilt angles (120o 240o). In the case with fast propagating mesoscale heating, positive

  6. Investigating a solar influence on cloud cover using the North American Regional Reanalysis data

    Directory of Open Access Journals (Sweden)

    Krahenbuhl Daniel Scott

    2015-01-01

    Full Text Available The controversial connection between cosmic rays, solar activity, and cloud cover is investigated using a climatological reconstructed reanalysis product: the North American Regional Reanalysis which provides high-resolution, low, mid-level, high, and total cloud cover data over a Lambert conformal conic projection permitting land/ocean discrimination. Pearson’s product-moment regional correlations were obtained between monthly cloud cover data and solar variability indicators, cosmic ray neutron monitors, several climatological indices, including the Atlantic Multidecadal Oscillation (AMO, and between cloud layers. Regions of the mid-latitude oceans exhibited a positive correlation with cosmic ray flux. Additionally, this maritime low cloud cover exhibits the only failed correlation significance with other altitudes. The cross correlation reveals that cloud cover is positively correlated everywhere but for ocean low cloud cover, supporting the unique response of the marine layer. The results of this investigation suggest that with the assumption that solar forcing does impact cloud cover, measurements of solar activity exhibits a slightly higher correlation than GCRs. The only instance where GCRs exhibit a positive regional correlation with cloud cover is for maritime low clouds. The AMO exerts the greatest control of cloud cover in the NARR domain.

  7. CloudSat observations of cloud-type distribution over the Indian summer monsoon region

    Directory of Open Access Journals (Sweden)

    K. V. Subrahmanyam

    2013-07-01

    Full Text Available The three-dimensional distribution of various cloud types over the Indian summer monsoon (ISM region using five years (2006–2010 of CloudSat observations during June-July-August-September months is discussed for the first time. As the radiative properties, latent heat released and microphysical properties of clouds differ largely depending on the cloud type, it becomes important to know what types of clouds occur over which region. In this regard, the present analysis establishes the three-dimensional distribution of frequency of occurrence of stratus (St, stratocumulus (Sc, nimbostratus (Ns, cumulus (Cu, altocumulus (Ac, altostratus (As, cirrus (Ci and deep convective (DC clouds over the ISM region. The results show that the various cloud types preferentially occur over some regions of the ISM, which are consistent during all the years of observations. It is found that the DC clouds frequently occur over northeast of Bay of Bengal (BoB, Ci clouds over a wide region of south BoB–Indian peninsula–equatorial Indian Ocean, and Sc clouds over the north Arabian Sea. Ac clouds preferentially occur over land, and a large amount of As clouds are found over BoB. The occurrence of both St and Ns clouds over the study region is much lower than all other cloud types.The interannual variability of all these clouds including their vertical distribution is discussed. It is envisaged that the present study opens up possibilities to quantify the feedback of individual cloud type in the maintenance of the ISM through radiative forcing and latent heat release.

  8. CORE COMPETENCES OF PIRACY AND MARITIME TERRORISM

    Directory of Open Access Journals (Sweden)

    Piotr Gawliczek

    2016-10-01

    Full Text Available The intensity of the attacks, the level of violence, the scale of destruction in the maritime areas forces creation of certain security conditions. Recognizing the enemy - piracy and maritime terrorism - by identifying their resources, skills and competences is necessary action in building the safety of vessels and maritime infrastructure. Building competence of terrorist organization and maritime piracy requires the involvement of many interrelated resources and their proper coordination. It seems that, as in a business model, in these criminal organizations there are similar resources, skills and competences that determine the advantage and strategic value of the organization. However, the weight of each factor is different. The same assumption can be related to piracy and the activities of the terrorist organization at sea. The results of the study suggest that the main sources of success of analyzed criminal organizations generate harm for national security. In the case of piracy, they result from the following spheres: human capital, attributable to the skills capital; structural capital, belonging to innovation capital; relational capital, depending on customers' capital. As for terrorist activities, they stem from the spheres of: human capital, belonging to social capital; structural capital, attributable to the process capital; relational capital and determined by capital of standing out. In summary, this article is intended to show a terrorist organization and maritime piracy through the prism of resources theory, skills and competences of strategic management. As one of the first, it places many questions, formulate some theses in the area of competences of organizations. Answering the questions, verification of posed theses, requires also in-depth research that will be published in subsequent works.

  9. An introduction to the Research Innovation and Knowledge Management Roadmap for the South African Maritime Sector

    CSIR Research Space (South Africa)

    Funke, Nicola S

    2017-04-01

    Full Text Available OBJECTIVES & ACTIONS We have a maritime culture and recognise and learn from our maritime history 1 Foster national maritime pride 3 Develop and communicate a co-authored discourse on South Africa’s maritime history 2 Support maritime historical... and training facilities 6 Build and retain skills in the maritime sector 2 Support and develop maritime-focused technology and innovation 7 OBJECTIVES & ACTIONS Conduct humanities and social science research on pertinent issues 3 Create knowledge...

  10. The Explicit-Cloud Parameterized-Pollutant hybrid approach for aerosol-cloud interactions in multiscale modeling framework models: tracer transport results

    International Nuclear Information System (INIS)

    Jr, William I Gustafson; Berg, Larry K; Easter, Richard C; Ghan, Steven J

    2008-01-01

    All estimates of aerosol indirect effects on the global energy balance have either completely neglected the influence of aerosol on convective clouds or treated the influence in a highly parameterized manner. Embedding cloud-resolving models (CRMs) within each grid cell of a global model provides a multiscale modeling framework for treating both the influence of aerosols on convective as well as stratiform clouds and the influence of clouds on the aerosol, but treating the interactions explicitly by simulating all aerosol processes in the CRM is computationally prohibitive. An alternate approach is to use horizontal statistics (e.g., cloud mass flux, cloud fraction, and precipitation) from the CRM simulation to drive a single-column parameterization of cloud effects on the aerosol and then use the aerosol profile to simulate aerosol effects on clouds within the CRM. Here, we present results from the first component of the Explicit-Cloud Parameterized-Pollutant parameterization to be developed, which handles vertical transport of tracers by clouds. A CRM with explicit tracer transport serves as a benchmark. We show that this parameterization, driven by the CRM's cloud mass fluxes, reproduces the CRM tracer transport significantly better than a single-column model that uses a conventional convective cloud parameterization

  11. The Explicit-Cloud Parameterized-Pollutant hybrid approach for aerosol-cloud interactions in multiscale modeling framework models: tracer transport results

    Energy Technology Data Exchange (ETDEWEB)

    Jr, William I Gustafson; Berg, Larry K; Easter, Richard C; Ghan, Steven J [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, PO Box 999, MSIN K9-30, Richland, WA (United States)], E-mail: William.Gustafson@pnl.gov

    2008-04-15

    All estimates of aerosol indirect effects on the global energy balance have either completely neglected the influence of aerosol on convective clouds or treated the influence in a highly parameterized manner. Embedding cloud-resolving models (CRMs) within each grid cell of a global model provides a multiscale modeling framework for treating both the influence of aerosols on convective as well as stratiform clouds and the influence of clouds on the aerosol, but treating the interactions explicitly by simulating all aerosol processes in the CRM is computationally prohibitive. An alternate approach is to use horizontal statistics (e.g., cloud mass flux, cloud fraction, and precipitation) from the CRM simulation to drive a single-column parameterization of cloud effects on the aerosol and then use the aerosol profile to simulate aerosol effects on clouds within the CRM. Here, we present results from the first component of the Explicit-Cloud Parameterized-Pollutant parameterization to be developed, which handles vertical transport of tracers by clouds. A CRM with explicit tracer transport serves as a benchmark. We show that this parameterization, driven by the CRM's cloud mass fluxes, reproduces the CRM tracer transport significantly better than a single-column model that uses a conventional convective cloud parameterization.

  12. Convection and stellar oscillations

    DEFF Research Database (Denmark)

    Aarslev, Magnus Johan

    2017-01-01

    for asteroseismology, because of the challenges inherent in modelling turbulent convection in 1D stellar models. As a result of oversimplifying the physics near the surface, theoretical calculations systematically overestimate the oscillation frequencies. This has become known as the asteroseismic surface effect. Due...... to lacking better options, this frequency difference is typically corrected for with ad-hoc formulae. The topic of this thesis is the improvement of 1D stellar convection models and the effects this has on asteroseismic properties. The source of improvements is 3D simulations of radiation...... atmospheres to replace the outer layers of stellar models. The additional turbulent pressure and asymmetrical opacity effects in the atmosphere model, compared to convection in stellar evolution models, serve to expand the atmosphere. The enlarged acoustic cavity lowers the pulsation frequencies bringing them...

  13. Active control of convection

    Energy Technology Data Exchange (ETDEWEB)

    Bau, H.H. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    1995-12-31

    Using stability theory, numerical simulations, and in some instances experiments, it is demonstrated that the critical Rayleigh number for the bifurcation (1) from the no-motion (conduction) state to the motion state and (2) from time-independent convection to time-dependent, oscillatory convection in the thermal convection loop and Rayleigh-Benard problems can be significantly increased or decreased. This is accomplished through the use of a feedback controller effectuating small perturbations in the boundary data. The controller consists of sensors which detect deviations in the fluid`s temperature from the motionless, conductive values and then direct actuators to respond to these deviations in such a way as to suppress the naturally occurring flow instabilities. Actuators which modify the boundary`s temperature/heat flux are considered. The feedback controller can also be used to control flow patterns and generate complex dynamic behavior at relatively low Rayleigh numbers.

  14. Convective-stratiform rainfall separation of Typhoon Fitow (2013: A 3D WRF modeling study

    Directory of Open Access Journals (Sweden)

    Huiyan Xu

    2018-01-01

    Full Text Available Surface precipitation budget equation in a three-dimensional (3D WRF model framework is derived. By applying the convective-stratiform partition method to the surface precipitation budget equation in the 3D model, this study separated convective and stratiform rainfall of typhoon Fitow (2013. The separations are further verified by examining statistics of vertical velocity, surface precipitation budget, and cloud microphysical budget. Results show that water vapor convergence moistens local atmosphere and offsets hydrometeor divergence, and producing convective rainfall, while hydrometeor convergence primarily supports stratiform rainfall, since water vapor divergence and local atmospheric drying generally cancelled out. Mean ascending motions are prevailing in the entire troposphere in the convective region, whereas mean descending motions occur below 5 km and mean ascending motions occur above in the stratiform region. The frequency distribution of vertical velocity shows vertical velocity has wide distribution with the maximum values up to 13 m s-1 in the convective regions, whereas it has narrow distribution with absolute values confined within 7 m s-1 in the stratiform region. Liquid cloud microphysics is dominant in convective regions and ice cloud microphysics is dominant in stratiform regions. These indicate that the statistics results are generally consistent with the corresponding physical characteristics of the convective-stratiform rainfall structures generalized by previous studies.

  15. Convectively coupled Kelvin waves in aquachannel simulations: 2. Life cycle and dynamical-convective coupling

    Science.gov (United States)

    Blanco, Joaquín. E.; Nolan, David S.; Mapes, Brian E.

    2016-10-01

    This second part of a two-part study uses Weather Research and Forecasting simulations with aquachannel and aquapatch domains to investigate the time evolution of convectively coupled Kelvin waves (CCKWs). Power spectra, filtering, and compositing are combined with object-tracking methods to assess the structure and phase speed propagation of CCKWs during their strengthening, mature, and decaying phases. In this regard, we introduce an innovative approach to more closely investigate the wave (Kelvin) versus entity (super cloud cluster or "SCC") dualism. In general, the composite CCKW structures represent a dynamical response to the organized convective activity. However, pressure and thermodynamic fields in the boundary layer behave differently. Further analysis of the time evolution of pressure and low-level moist static energy finds that these fields propagate eastward as a "moist" Kelvin wave (MKW), faster than the envelope of organized convection or SCC. When the separation is sufficiently large the SCC dissipates, and a new SCC generates to the east, in the region of strongest negative pressure perturbations. We revisit the concept itself of the "coupling" between convection and dynamics, and we also propose a conceptual model for CCKWs, with a clear distinction between the SCC and the MKW components.

  16. Cloud Cover

    Science.gov (United States)

    Schaffhauser, Dian

    2012-01-01

    This article features a major statewide initiative in North Carolina that is showing how a consortium model can minimize risks for districts and help them exploit the advantages of cloud computing. Edgecombe County Public Schools in Tarboro, North Carolina, intends to exploit a major cloud initiative being refined in the state and involving every…

  17. Cloud Control

    Science.gov (United States)

    Ramaswami, Rama; Raths, David; Schaffhauser, Dian; Skelly, Jennifer

    2011-01-01

    For many IT shops, the cloud offers an opportunity not only to improve operations but also to align themselves more closely with their schools' strategic goals. The cloud is not a plug-and-play proposition, however--it is a complex, evolving landscape that demands one's full attention. Security, privacy, contracts, and contingency planning are all…

  18. Convective transport in tokamaks

    International Nuclear Information System (INIS)

    D'Ippolito, D.A.; Myra, J.R.; Russell, D.A.; Krasheninnikov, S.I.; Pigarov, A.Yu.; Yu, G.Q.; Xu, X.Q.; Nevins, W.M.

    2005-01-01

    Scrape-off-layer (SOL) convection in fusion experiments appears to be a universal phenomenon that can 'short-circuit' the divertor in some cases. The theory of 'blob' transport provides a simple and robust physical paradigm for studying convective transport. This paper summarizes recent advances in the theory of blob transport and its comparison with 2D and 3D computer simulations. We also discuss the common physical basis relating radial transport of blobs, pellets, and ELMs and a new blob regime that may lead to a connection between blob transport and the density limit. (author)

  19. Physics of Stellar Convection

    Science.gov (United States)

    Arnett, W. David

    2009-05-01

    We review recent progress using numerical simulations as a testbed for development of a theory of stellar convection, much as envisaged by John von Newmann. Necessary features of the theory, non-locality and fluctuations, are illustrated by computer movies. It is found that the common approximation of convection as a diffusive process presents the wrong physical picture, and improvements are suggested. New observational results discussed at the conference are gratifying in their validation of some of our theoretical ideas, especially the idea that SNIb and SNIc events are related to the explosion of massive star cores which have been stripped by mass loss and binary interactions [1

  20. Parameterizing convective organization

    Directory of Open Access Journals (Sweden)

    Brian Earle Mapes

    2011-06-01

    Full Text Available Lateral mixing parameters in buoyancy-driven deep convection schemes are among the most sensitive and important unknowns in atmosphere models. Unfortunately, there is not a true optimum value for plume mixing rate, but rather a dilemma or tradeoff: Excessive dilution of updrafts leads to unstable stratification bias in the mean state, while inadequate dilution allows deep convection to occur too easily, causing poor space and time distributions and variability. In this too-small parameter space, compromises are made based on competing metrics of model performance. We attempt to escape this “entrainment dilemma” by making bulk plume parameters (chiefly entrainment rate depend on a new prognostic variable (“organization,” org meant to reflect the rectified effects of subgrid-scale structure in meteorological fields. We test an org scheme in the Community Atmosphere Model (CAM5 with a new unified shallow-deep convection scheme (UW-ens, a 2-plume version of the University of Washington scheme. Since buoyant ascent involves natural selection, subgrid structure makes convection systematically deeper and stronger than the pure unorganized case: plumes of average (or randomly sampled air rising in the average environment. To reflect this, org is nonnegative, but we leave it dimensionless. A time scale characterizes its behavior (here ∼3 h for a 2o model. Currently its source is rain evaporation, but other sources can be added easily. We also let org be horizontally transported by advection, as a mass-weighted mean over the convecting layer. Linear coefficients link org to a plume ensemble, which it assists via: 1 plume base warmth above the mean temperature 2 plume radius enhancement (reduced mixing, and 3 increased probability of overlap in a multi-plume scheme, where interactions benefit later generations (this part has only been implemented in an offline toy column model. Since rain evaporation is a source for org, it functions as a time

  1. Mathematical models of convection

    CERN Document Server

    Andreev, Victor K; Goncharova, Olga N; Pukhnachev, Vladislav V

    2012-01-01

    Phenomena of convection are abundant in nature as well as in industry. This volume addresses the subject of convection from the point of view of both, theory and application. While the first three chapters provide a refresher on fluid dynamics and heat transfer theory, the rest of the book describes the modern developments in theory. Thus it brings the reader to the ""front"" of the modern research. This monograph provides the theoretical foundation on a topic relevant to metallurgy, ecology, meteorology, geo-and astrophysics, aerospace industry, chemistry, crystal physics, and many other fiel

  2. Convective aggregation in realistic convective-scale simulations

    OpenAIRE

    Holloway, Christopher E.

    2017-01-01

    To investigate the real-world relevance of idealized-model convective self-aggregation, five 15-day cases of real organized convection in the tropics are simulated. These include multiple simulations of each case to test sensitivities of the convective organization and mean states to interactive radiation, interactive surface fluxes, and evaporation of rain. These simulations are compared to self-aggregation seen in the same model configured to run in idealized radiative-convective equilibriu...

  3. Discrete ordinate theory of radiative transfer. 2: Scattering from maritime haze

    Science.gov (United States)

    Kattawar, G. W.; Plass, G. N.; Catchings, F. E.

    1971-01-01

    Discrete ordinate theory was used to calculate the reflected and transmitted radiance of photons which have interacted with plane parallel maritime haze layers. The results are presented for three solar zenith angles, three values of the surface albedo, and a range of optical thicknesses from very thin to very thick. The diffuse flux at the lower boundary and the cloud albedo were tabulated. The forward peak and other features in the single scattered phase function caused the radiance in many cases to be very different from that for Rayleigh scattering. The variation of the radiance with both the zenith or nadir angle and the azimuthal angle is more marked, and the relative limb darkening under very thick layers is greater, for haze than for Rayleigh scattering. The downward diffuse flux at the lower boundary for A = O is always greater and the cloud albedo is always less for haze than for Rayleigh layers.

  4. CDM Convective Forecast Planning guidance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The CDM Convective Forecast Planning (CCFP) guidance product provides a foreast of en-route aviation convective hazards. The forecasts are updated every 2 hours and...

  5. Prognostic cloud water in the Los Alamos general circulation model

    International Nuclear Information System (INIS)

    Kristjansson, J.E.; Kao, C.Y.J.

    1993-01-01

    Most of today's general circulation models (GCMS) have a greatly simplified treatment of condensation and clouds. Recent observational studies of the earth's radiation budget have suggested cloud-related feedback mechanisms to be of tremendous importance for the issue of global change. Thus, there has arisen an urgent need for improvements in the treatment of clouds in GCMS, especially as the clouds relate to radiation. In the present paper, we investigate the effects of introducing pregnostic cloud water into the Los Alamos GCM. The cloud water field, produced by both stratiform and convective condensation, is subject to 3-dimensional advection and vertical diffusion. The cloud water enters the radiation calculations through the long wave emissivity calculations. Results from several sensitivity simulations show that realistic cloud water and precipitation fields can be obtained with the applied method. Comparisons with observations show that the most realistic results are obtained when more sophisticated schemes for moist convection are introduced at the same time. The model's cold bias is reduced and the zonal winds become stronger, due to more realistic tropical convection

  6. Presentation on Tropical Mesoscale convective Systems and ...

    Indian Academy of Sciences (India)

    IAS Admin

    Shallow convection- 70% of the storm heights are below 6 km. ♢ Deep convection ... Decay convection, the convective top is found at a higher altitude than deep .... Stratospheric Fountain – Two step process. Warm tropopause- preferable for.

  7. Maritime climate influence on chaparral composition and diversity in the coast range of central California.

    Science.gov (United States)

    Vasey, Michael C; Parker, V Thomas; Holl, Karen D; Loik, Michael E; Hiatt, Seth

    2014-09-01

    We investigated the hypothesis that maritime climatic factors associated with summer fog and low cloud stratus (summer marine layer) help explain the compositional diversity of chaparral in the coast range of central California. We randomly sampled chaparral species composition in 0.1-hectare plots along a coast-to-interior gradient. For each plot, climatic variables were estimated and soil samples were analyzed. We used Cluster Analysis and Principle Components Analysis to objectively categorize plots into climate zone groups. Climate variables, vegetation composition and various diversity measures were compared across climate zone groups using ANOVA and nonmetric multidimensional scaling. Differences in climatic variables that relate to summer moisture availability and winter freeze events explained the majority of variance in measured conditions and coincided with three chaparral assemblages: maritime (lowland coast where the summer marine layer was strongest), transition (upland coast with mild summer marine layer influence and greater winter precipitation), and interior sites that generally lacked late summer water availability from either source. Species turnover (β-diversity) was higher among maritime and transition sites than interior sites. Coastal chaparral differs from interior chaparral in having a higher obligate seeder to facultative seeder (resprouter) ratio and by being dominated by various Arctostaphylos species as opposed to the interior dominant, Adenostoma fasciculatum. The maritime climate influence along the California central coast is associated with patterns of woody plant composition and β-diversity among sites. Summer fog in coastal lowlands and higher winter precipitation in coastal uplands combine to lower late dry season water deficit in coastal chaparral and contribute to longer fire return intervals that are associated with obligate seeders and more local endemism. Soil nutrients are comparatively less important in explaining plant

  8. Convective overshooting in stars

    NARCIS (Netherlands)

    Andrássy, R.

    2015-01-01

    Numerous observations provide evidence that the standard picture, in which convective mixing is limited to the unstable layers of a star, is incomplete. The mixing layers in real stars are significantly more extended than what the standard models predict. Some of the observations require changing

  9. Cloud Computing Fundamentals

    Science.gov (United States)

    Furht, Borko

    In the introductory chapter we define the concept of cloud computing and cloud services, and we introduce layers and types of cloud computing. We discuss the differences between cloud computing and cloud services. New technologies that enabled cloud computing are presented next. We also discuss cloud computing features, standards, and security issues. We introduce the key cloud computing platforms, their vendors, and their offerings. We discuss cloud computing challenges and the future of cloud computing.

  10. Analysis of co-located MODIS and CALIPSO observations near clouds

    Directory of Open Access Journals (Sweden)

    T. Várnai

    2012-02-01

    Full Text Available This paper aims at helping synergistic studies in combining data from different satellites for gaining new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects. In particular, the paper examines the way cloud information from the MODIS (MODerate resolution Imaging Spectroradiometer imager can refine our perceptions based on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization lidar measurements about the systematic aerosol changes that occur near clouds.

    The statistical analysis of a yearlong dataset of co-located global maritime observations from the Aqua and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellites reveals that MODIS's multispectral imaging ability can greatly help the interpretation of CALIOP observations. The results show that imagers on Aqua and CALIPSO yield very similar pictures, and that the discrepancies – due mainly to wind drift and differences in view angle – do not significantly hinder aerosol measurements near clouds. By detecting clouds outside the CALIOP track, MODIS reveals that clouds are usually closer to clear areas than CALIOP data alone would suggest. The paper finds statistical relationships between the distances to clouds in MODIS and CALIOP data, and proposes a rescaling approach to statistically account for the impact of clouds outside the CALIOP track even when MODIS cannot reliably detect low clouds, for example at night or over sea ice. Finally, the results show that the typical distance to clouds depends on both cloud coverage and cloud type, and accordingly varies with location and season. In maritime areas perceived cloud free, the global median distance to clouds below 3 km altitude is in the 4–5 km range.

  11. 33 CFR 103.305 - Composition of an Area Maritime Security (AMS) Committee.

    Science.gov (United States)

    2010-07-01

    ... port stakeholders having a special competence in maritime security; and (7) Port stakeholders affected... Security (AMS) Committee. 103.305 Section 103.305 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARITIME SECURITY: AREA MARITIME SECURITY Area Maritime...

  12. Cloud regimes as phase transitions

    Science.gov (United States)

    Stechmann, Samuel; Hottovy, Scott

    2017-11-01

    Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes - open versus closed cells - fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells (POCs) as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. Similar viewpoints of deep convection and self-organized criticality will also be discussed. With these new conceptual viewpoints, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions. The research of S.N.S. is partially supported by a Sloan Research Fellowship, ONR Young Investigator Award N00014-12-1-0744, and ONR MURI Grant N00014-12-1-0912.

  13. Cloud Computing

    CERN Document Server

    Baun, Christian; Nimis, Jens; Tai, Stefan

    2011-01-01

    Cloud computing is a buzz-word in today's information technology (IT) that nobody can escape. But what is really behind it? There are many interpretations of this term, but no standardized or even uniform definition. Instead, as a result of the multi-faceted viewpoints and the diverse interests expressed by the various stakeholders, cloud computing is perceived as a rather fuzzy concept. With this book, the authors deliver an overview of cloud computing architecture, services, and applications. Their aim is to bring readers up to date on this technology and thus to provide a common basis for d

  14. Simulating moist convection with a quasi-elastic sigma coordinate model

    CSIR Research Space (South Africa)

    Bopape, Mary-Jane M

    2012-10-01

    Full Text Available : Corrected TOGA COARE Sounding Humidity Data: Impact on Diagnosed Properties of Convection and Climate over the Warm Pool. Journal of Climate, 12, 2370-2384. WW, X Wu and MW Moncrieff, 1996: Cloud-Resolving Modeling of Tropical Cloud Systems during Phase... during the suppressed phase of a Madden-Julian Oscillation: Comparing single-column models with cloud resolving models. Quarterly Journal of the Royal Meteorological Society, 1-22. Sun S and W Sun, 2002: A One-dimensional Time Dependent Cloud Model...

  15. Convective Propagation Characteristics Using a Simple Representation of Convective Organization

    Science.gov (United States)

    Neale, R. B.; Mapes, B. E.

    2016-12-01

    Observed equatorial wave propagation is intimately linked to convective organization and it's coupling to features of the larger-scale flow. In this talk we a use simple 4 level model to accommodate vertical modes of a mass flux convection scheme (shallow, mid-level and deep). Two paradigms of convection are used to represent convective processes. One that has only both random (unorganized) diagnosed fluctuations of convective properties and one with organized fluctuations of convective properties that are amplified by previously existing convection and has an explicit moistening impact on the local convecting environment We show a series of model simulations in single-column, 2D and 3D configurations, where the role of convective organization in wave propagation is shown to be fundamental. For the optimal choice of parameters linking organization to local atmospheric state, a broad array of convective wave propagation emerges. Interestingly the key characteristics of propagating modes are the low-level moistening followed by deep convection followed by mature 'large-scale' heating. This organization structure appears to hold firm across timescales from 5-day wave disturbances to MJO-like wave propagation.

  16. The maritime law of the Baltic Sea

    DEFF Research Database (Denmark)

    Jahnke, Carsten

    2017-01-01

    Before the end of the 13th century, the Baltic seamen created a law system codi ed in Bjarkey and Söderköping and then Schleswig laws. The increasing Germanic domination of Baltic navigation resulted in the creation of speci c maritime laws for Lübeck and Hamburg before the introduction of the Laws...... lois de Bjarkey et de Söderköping, puis de Schleswig. La progressive domination germanique sur la navigation en Baltique a pour conséquence la création de lois maritimes propres à Lübeck et à Hambourg, avant l’introduction des Rôles d’Oléron, traduits en bas-allemand pour former le Vonesse von Damme...

  17. Information Exchange Automation in Maritime Transport

    Directory of Open Access Journals (Sweden)

    Zbigniew Pietrzykowski

    2014-06-01

    Full Text Available To ensure the safety of maritime transport the access to information must be provided through a commonly used services. However, an equally important task is to determine or agree on interpretation of incoming data and assessment of a current and predicted navigational situation and, in further step, intentions of the participants in the transport process. Thanks to the standardization of information format, automatic information exchange gets increasingly wider. Another step ahead is automatic interpretation of information and automation of negotiation processes - intelligent communication. Rapid development of IT and ICT technologies creates such opportunities. This article presents the results of research on a system of automatic communication and co-operation in maritime transport.

  18. Naval Maritime Physician : Roles and Challenges

    Directory of Open Access Journals (Sweden)

    Ranjan Sarkar

    2016-01-01

    Roles and challenges: Good maritime medicalpractice involves meeting numerous challenges of clinical, occupational, emergency, trauma and psychiatric medicine, in addition on board physicians must also have, in depth knowledge of pschycosomatic conditions due to stress andfatigue of crew and special conditions such as diving accidents and accidents involving aquatic animals. The situation on board requires extraordinary skills as interventions are difficult, both physically and technically, because the conditions at sea are often acrobatic and at certain times evacuation is also not possible due to weather and operational constraints. Thus the role naval doctor on board ships is truly of an all round physicians, a team mate and a good leader. Conclusion: In conclusion, responsibilities of Naval Maritime Physician is not limited to clinical activities but is multifaceted and objective training about the specifics of warships′ environment and related health problems is the key to achieve professional excellence in every sphere.

  19. Micro-Physical characterisation of Convective & Stratiform Rainfall at Tropics

    Science.gov (United States)

    Sreekanth, T. S.

    Large Micro-Physical characterisation of Convective & Stratiform Rainfall at Tropics begin{center} begin{center} Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , and V Sasi Kumar (2) *Centre for Earth Science Studies, Akkulam, Thiruvananthapuram (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) 32. NCC Nagar, Peroorkada, Thiruvananthapuram ABSTRACT Micro-physical parameters of rainfall such as rain drop size & fall speed distribution, mass weighted mean diameter, Total no. of rain drops, Normalisation parameters for rain intensity, maximum & minimum drop diameter from different rain intensity ranges, from both stratiform and convective rain events were analysed. Convective -Stratiform classification was done by the method followed by Testud et al (2001) and as an additional information electrical behaviour of clouds from Atmospheric Electric Field Mill was also used. Events which cannot be included in both types are termed as 'mixed precipitation' and identified separately. For the three years 2011, 2012 & 2013, rain events from both convective & stratiform origin are identified from three seasons viz Pre-Monsoon (March-May), Monsoon (June-September) and Post-Monsoon (October-December). Micro-physical characterisation was done for each rain events and analysed. Ground based and radar observations were made and classification of stratiform and convective rainfall was done by the method followed by Testud et al (2001). Radar bright band and non bright band analysis was done for confimation of stratifom and convective rain respectievely. Atmospheric electric field data from electric field mill is also used for confirmation of convection during convective events. Statistical analyses revealed that the standard deviation of rain drop size in higher rain rates are higher than in lower rain rates. Normalised drop size distribution is ploted for selected events from both forms. Inter relations between various precipitation parameters were analysed in three

  20. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2008-01-01

    Aerosols and especially their effect on clouds are one of the key components of the climate system and the hydrological cycle [Ramanathan et al., 2001]. Yet, the aerosol effect on clouds remains largely unknown and the processes involved not well understood. A recent report published by the National Academy of Science states "The greatest uncertainty about the aerosol climate forcing - indeed, the largest of all the uncertainties about global climate forcing - is probably the indirect effect of aerosols on clouds [NRC, 2001]." The aerosol effect on clouds is often categorized into the traditional "first indirect (i.e., Twomey)" effect on the cloud droplet sizes for a constant liquid water path [Twomey, 1977] and the "semi-direct" effect on cloud coverage [e.g., Ackerman et al ., 2001]." Enhanced aerosol concentrations can also suppress warm rain processes by producing a narrow droplet spectrum that inhibits collision and coalescence processes [e.g., Squires and Twomey, 1961; Warner and Twomey, 1967; Warner, 1968; Rosenfeld, 19991. The aerosol effect on precipitation processes, also known as the second type of aerosol indirect effect [Albrecht, 1989], is even more complex, especially for mixed-phase convective clouds. Table 1 summarizes the key observational studies identifying the microphysical properties, cloud characteristics, thermodynamics and dynamics associated with cloud systems from high-aerosol continental environments. For example, atmospheric aerosol concentrations can influence cloud droplet size distributions, warm-rain process, cold-rain process, cloud-top height, the depth of the mixed phase region, and occurrence of lightning. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing an enhanced source of cloud condensation nuclei (CCN). Hypotheses have been developed to explain the effect of urban regions on convection and precipitation [van den Heever and Cotton, 2007 and Shepherd, 2005

  1. The sensitivities of in cloud and cloud top phase distributions to primary ice formation in ICON-LEM

    Science.gov (United States)

    Beydoun, H.; Karrer, M.; Tonttila, J.; Hoose, C.

    2017-12-01

    Mixed phase clouds remain a leading source of uncertainty in our attempt to quantify cloud-climate and aerosol-cloud climate interactions. Nevertheless, recent advances in parametrizing the primary ice formation process, high resolution cloud modelling, and retrievals of cloud phase distributions from satellite data offer an excellent opportunity to conduct closure studies on the sensitivity of the cloud phase to microphysical and dynamical processes. Particularly, the reliability of satellite data to resolve the phase at the top of the cloud provides a promising benchmark to compare model output to. We run large eddy simulations with the new ICOsahedral Non-hydrostatic atmosphere model (ICON) to place bounds on the sensitivity of in cloud and cloud top phase to the primary ice formation process. State of the art primary ice formation parametrizations in the form of the cumulative ice active site density ns are implemented in idealized deep convective cloud simulations. We exploit the ability of ICON-LEM to switch between a two moment microphysics scheme and the newly developed Predicted Particle Properties (P3) scheme by running our simulations in both configurations for comparison. To quantify the sensitivity of cloud phase to primary ice formation, cloud ice content is evaluated against order of magnitude changes in ns at variable convective strengths. Furthermore, we assess differences between in cloud and cloud top phase distributions as well as the potential impact of updraft velocity on the suppression of the Wegener-Bergeron-Findeisen process. The study aims to evaluate our practical understanding of primary ice formation in the context of predicting the structure and evolution of mixed phase clouds.

  2. NATO Advanced Study Institute on Buoyant Convection in Geophysical Flows

    CERN Document Server

    Fedorovich, E; Viegas, D; Wyngaard, J

    1998-01-01

    Studies of convection in geophysical flows constitute an advanced and rapidly developing area of research that is relevant to problems of the natural environment. During the last decade, significant progress has been achieved in the field as a result of both experimental studies and numerical modelling. This led to the principal revision of the widely held view on buoyancy-driven turbulent flows comprising an organised mean component with superimposed chaotic turbulence. An intermediate type of motion, represented by coherent structures, has been found to play a key role in geophysical boundary layers and in larger scale atmospheric and hydrospheric circulations driven by buoyant forcing. New aspects of the interaction between convective motions and rotation have recently been discovered and investigated. Extensive experimental data have also been collected on the role of convection in cloud dynamics and microphysics. New theoretical concepts and approaches have been outlined regarding scaling and parameteriz...

  3. Green maritime transportation: Market based measures

    DEFF Research Database (Denmark)

    Psaraftis, Harilaos N.

    2016-01-01

    The purpose of this chapter is to introduce the concept of Market Based Measures (MBMs) to reduce Green House Gas (GHG) emissions from ships, and review several distinct MBM proposals that have been under consideration by the International Maritime Organization (IMO). The chapter discusses the me...... the mechanisms used by MBMs, and explores how the concept of the Marginal Abatement Cost (MAC) can be linked to MBMs. It also attempts to discuss the pros and cons of the submitted proposals....

  4. Technology Foresight in Emerging Maritime & Marine Economies

    DEFF Research Database (Denmark)

    Spaniol, Matthew Jon; Rohrbeck, René

    . The technologies are organized to support innovation and the development of new business areas, and sustains discussion via an online portal. The upshot for technology developers is the organization of the technological landscape. The upshot for academics is the expanded horizon of emerging technologies...... for anticipatory projects, development efforts, and policy considerations. An early iteration of the Radar covers: • Renewable ocean energy • Seabed mining & offshore technology • Marine biotechnology & aquaculture • Specialized vessels & infrastructure • Servicing emerging maritime & offshore activities...

  5. Modern Piracy: The Impact on Maritime Security

    Science.gov (United States)

    2008-01-01

    attacked Source: International Chamber of Commerce , Commercial Crime Bureau. http://www.eurocrime.it/sitelPiracy%20and%20Terrorism.pdf Piracy, simply put...agency of the International Chamber of Commerce (ICC), provide regular statistical data and reports of acts ofpiracy and armed robbery against ShipS.14...3: Key Maritime Choke-points / Piracy Hot Spots Source: International Chamber of Commerce , Commercial Crime Bureau. http://www.eurocrime.it/site

  6. Improving Human Resources Recruitment in Maritime Domain

    OpenAIRE

    Surugiu Felicia; Dragomir Cristina

    2011-01-01

    In order to improve maritime human resources recruitment, most crewing and shipping companies implement an internal procedure of recruitment and management of ship’s crew. Based on observations at several crewing companies, this paper presents an example of such procedure meant to ensure that qualified and competent personnel is recruited and all ships in the fleet have crew members understanding their roles, duties and responsibilities and capable of working effectively in teams

  7. The Land Component Role in Maritime Security

    Science.gov (United States)

    2016-12-31

    nations for resources. They must also confront maritime threats, which include piracy , armed robbery, damage to the marine environment (i.e. pollution...such as an armed attack from a military vessel. Most definitions also usually include security from crimes at sea, such as piracy , armed robbery...security through stability operations, one must accept that any effective government must focus on basic governmental functions – providing for the

  8. Maritime Security: Malaysia’s Persistent Problem

    Science.gov (United States)

    2012-01-01

    navies, and air forces of the littoral states.”20 In his keynote address at the 2011 Shangri-La Dialogue, Prime Minister Dato’ Sri Najib Tun Razak ...Monitor, Vol. 4 No. 3, 2006. Razak , Dato’ Sri Najib Tun, Prime Minister Malaysia. Keynote Address. Shangri-La Dialogue. Singapore, June 3, 2011... Razak , Dato’ Sri Najib , Deputy Prime Minister Malaysia, Address. Shangri-La Dialogue. Enhancing Maritime Security Cooperation. Singapore, 2005

  9. Aerosol-Cloud Interactions and Cloud Microphysical Properties in the Asir Region of Saudi Arabia

    Science.gov (United States)

    Kucera, P. A.; Axisa, D.; Burger, R. P.; Li, R.; Collins, D. R.; Freney, E. J.; Buseck, P. R.

    2009-12-01

    In recent advertent and inadvertent weather modification studies, a considerable effort has been made to understand the impact of varying aerosol properties and concentration on cloud properties. Significant uncertainties exist with aerosol-cloud interactions for which complex microphysical processes link the aerosol and cloud properties. Under almost all environmental conditions, increased aerosol concentrations within polluted air masses will enhance cloud droplet concentration relative to that in unperturbed regions. The interaction between dust particles and clouds are significant, yet the conditions in which dust particles become cloud condensation nuclei (CCN) are uncertain. In order to quantify this aerosol effect on clouds and precipitation, a field campaign was launched in the Asir region, located adjacent to the Red Sea in the southwest region of Saudi Arabia. Ground measurements of aerosol size distributions, hygroscopic growth factors, CCN concentrations as well as aircraft measurements of cloud hydrometeor size distributions were observed in the Asir region in August 2009. The presentation will include a summary of the analysis and results with a focus on aerosol-cloud interactions and cloud microphysical properties observed during the convective season in the Asir region.

  10. Free-Tropospheric Moisture Convergence and Tropical Convective Regimes

    Science.gov (United States)

    Masunaga, H.

    2014-12-01

    It is known that quiescent periods with only shallow cumuli prevalent are frequently observed even in the deep Tropics, which is considered from the climatological perspectives as an area harboring vigorous deep convection. It is argued in this work that the free-tropospheric (FT) moisture convergence is a crucial factor for separating the stable maintenance of isolated shallow cumuli in the quiescent periods from the self-sustaining growth of organized convective systems in the dynamic periods over tropical oceans. The analysis is based on a variety of satellite measurements including Aqua AIRS T and q soundings and QuikSCAT surface wind, composited with reference to the time before or after the occurrence of precipitating clouds detected by TRMM PR. The FT moisture convergence and updraft moisture flux at cloud base are then derived from this dataset under large-scale moisture budget constraint (see Figure). Free-tropospheric precipitation efficiency (FTPE), or the ratio of precipitation to updraft moisture flux at cloud base, is introduced as a measure of convective intensity (rather than the population) over the large-scale domain. The following hypothesis is discussed in light of the analysis results. Isolated shallow cumuli would stay shallow when large-scale FT moisture is diverging (although moisture is weakly converging when integrated over the whole troposphere) since an increase in cumulus population would be counteracted by an additional moisture divergence in the FT. When large-scale FT convergence is positive, in contrast, developing clouds would induce a more moisture input and allow an unstable growth to a highly organized convective system. Zero FT moisture convergence may serve as the neutrality separating the negative feedback acting in the quiescent regime from the positive feedback instrumental for the dynamic regime.

  11. Gregarious Convection and Radiative Feedbacks in Idealized Worlds

    Science.gov (United States)

    2016-08-29

    water,’’ PW, a very strong predictor of deep moist convection [Bretherton et al., 2004; Neelin et al., 2009]. These papers freely interchange VIMSE and...exist neither on the globe nor within the cloud model. Since mesoscales impose great computational costs on atmosphere models, as well as inconven...continuity. Bottom-heavy or ‘‘ shallow ’’ circulations are especially effective at transporting moisture (since it is concen- trated at low altitudes

  12. Cloud Computing

    DEFF Research Database (Denmark)

    Krogh, Simon

    2013-01-01

    with technological changes, the paradigmatic pendulum has swung between increased centralization on one side and a focus on distributed computing that pushes IT power out to end users on the other. With the introduction of outsourcing and cloud computing, centralization in large data centers is again dominating...... the IT scene. In line with the views presented by Nicolas Carr in 2003 (Carr, 2003), it is a popular assumption that cloud computing will be the next utility (like water, electricity and gas) (Buyya, Yeo, Venugopal, Broberg, & Brandic, 2009). However, this assumption disregards the fact that most IT production......), for instance, in establishing and maintaining trust between the involved parties (Sabherwal, 1999). So far, research in cloud computing has neglected this perspective and focused entirely on aspects relating to technology, economy, security and legal questions. While the core technologies of cloud computing (e...

  13. Mobile Clouds

    DEFF Research Database (Denmark)

    Fitzek, Frank; Katz, Marcos

    A mobile cloud is a cooperative arrangement of dynamically connected communication nodes sharing opportunistic resources. In this book, authors provide a comprehensive and motivating overview of this rapidly emerging technology. The book explores how distributed resources can be shared by mobile...... users in very different ways and for various purposes. The book provides many stimulating examples of resource-sharing applications. Enabling technologies for mobile clouds are also discussed, highlighting the key role of network coding. Mobile clouds have the potential to enhance communications...... performance, improve utilization of resources and create flexible platforms to share resources in very novel ways. Energy efficient aspects of mobile clouds are discussed in detail, showing how being cooperative can bring mobile users significant energy saving. The book presents and discusses multiple...

  14. Risk Assessment in the Maritime Industry

    Directory of Open Access Journals (Sweden)

    M. Mousavi

    2017-02-01

    Full Text Available Risk assessment is a well-developed field which many operators are currently applying to improve their operations and reduce their risk exposure. This paper is intended to provide an overview of the risk assessment for mariners in the Maritime transportation. The risks addressed are primarily those affecting the safety of a vessel, facility or operation. The concept of risk is defined, and the methods available to assess the risks associated with an operation are described. Regulatory requirements that have prompted the development of modern risk assessment practices are described, and future regulatory trends are discussed. There are many different analysis techniques and models that have been developed to aid in conducting risk assessments. A key to any successful risk analysis is choosing the right method (or combination of methods for the situation at hand. This is achieved through critical analysis of the available data concerning marine crises. This paper provides a brief introduction to some of the analysis methods available and suggests risk analysis approaches to support different types of decision making within the maritime transportation to cope with crises. Finally, as awareness of risk assessment increases, the benefits which can be realized through its application will continue to increase. Organizations in both the public and the private sector are becoming more and more familiar with the benefits associated with risk-based approaches to managing safety and consequently reducing crisis in maritime transportation.

  15. Characteristic and factors of competitive maritime industry clusters in Indonesia

    Science.gov (United States)

    Marlyana, N.; Tontowi, A. E.; Yuniarto, H. A.

    2017-12-01

    Indonesia is situated in the strategic position between two oceans therefore is identified as a maritime state. The fact opens big opportunity to build a competitive maritime industry. However, potential factors to boost the competitive maritime industry still need to be explored. The objective of this paper is then to determine the main characteristics and potential factors of competitive maritime industry cluster. Qualitative analysis based on literature review has been carried out in two aspects. First, benchmarking analysis conducted to distinguish the most relevant factors of maritime clusters in several countries in Europe (Norway, Spain, South West of England) and Asia (China, South Korea, Malaysia). Seven key dimensions are used for this benchmarking. Secondly, the competitiveness of maritime clusters in Indonesia was diagnosed through a reconceptualization of Porter’s Diamond model. There were four interlinked of advanced factors in and between companies within clusters, which can be influenced in a proactive way by government.

  16. INMARSAT - The International Maritime Satellite Organization: Origins and structure

    Science.gov (United States)

    Doyle, S. E.

    1977-01-01

    The third session of the International Conference on the Establishment of an International Maritime Satellite System established the International Maritime Satellite Organization (INMARSAT) in 1976. Its main functions are to improve maritime communications via satellite, thereby facilitating more efficient emergency communications, ship management, and maritime public correspondence services. INMARSAT's aims are similar to those of the Intergovernmental Maritime Consultative Organization (IMCO), the main United Nations organization dealing with maritime affairs. The specific functions of INMARSAT have been established by an Intersessional Working Group (IWG) which met three times between general conference meetings. Initial investment shares for the creation of INMARSAT were shared by the United States (17%), the United Kingdom (12%), the U.S.S.R. (11%), Norway (9.50%), Japan (8.45%), Italy (4.37%), and France (3.50%).

  17. Development of a moisture scheme for the explicit numerical simulation of moist convection

    CSIR Research Space (South Africa)

    Bopape, Mary-Jane M

    2010-09-01

    Full Text Available .kashan.co.za] Development of a moisture scheme for the explicit numerical simulation of moist convection M BOPAPE, F ENGELBRECHT, D RANDALL AND W LANDMAN CSIR Natural Resources and the Environment, PO Box 395, Pretoria, 0001, South Africa Email: mbopape... sigma coordinate model that incorporates moisture effects, so that it can simulate convective clouds and precipitation. moisture terms equivalent to those of the miller and pearce (1974) model are incorporated in the equation set used: ; (1) ; (2...

  18. A case study of microphysical structures and hydrometeor phase in convection using radar Doppler spectra at Darwin, Australia

    International Nuclear Information System (INIS)

    Riihimaki, Laura D.; Comstock, J. M.; Luke, E.; Thorsen, T. J.; Fu, Q.

    2017-01-01

    To understand the microphysical processes that impact diabatic heating and cloud lifetimes in convection, we need to characterize the spatial distribution of supercooled liquid water. To address this observational challenge, ground-based vertically pointing active sensors at the Darwin Atmospheric Radiation Measurement site are used to classify cloud phase within a deep convective cloud. The cloud cannot be fully observed by a lidar due to signal attenuation. Therefore, we developed an objective method for identifying hydrometeor classes, including mixed-phase conditions, using k-means clustering on parameters that describe the shape of the Doppler spectra from vertically pointing Ka-band cloud radar. Furthermore, this approach shows that multiple, overlapping mixed-phase layers exist within the cloud, rather than a single region of supercooled liquid. Diffusional growth calculations show that the conditions for the Wegener-Bergeron-Findeisen process exist within one of these mixed-phase microstructures.

  19. A case study of microphysical structures and hydrometeor phase in convection using radar Doppler spectra at Darwin, Australia

    Science.gov (United States)

    Riihimaki, L. D.; Comstock, J. M.; Luke, E.; Thorsen, T. J.; Fu, Q.

    2017-07-01

    To understand the microphysical processes that impact diabatic heating and cloud lifetimes in convection, we need to characterize the spatial distribution of supercooled liquid water. To address this observational challenge, ground-based vertically pointing active sensors at the Darwin Atmospheric Radiation Measurement site are used to classify cloud phase within a deep convective cloud. The cloud cannot be fully observed by a lidar due to signal attenuation. Therefore, we developed an objective method for identifying hydrometeor classes, including mixed-phase conditions, using k-means clustering on parameters that describe the shape of the Doppler spectra from vertically pointing Ka-band cloud radar. This approach shows that multiple, overlapping mixed-phase layers exist within the cloud, rather than a single region of supercooled liquid. Diffusional growth calculations show that the conditions for the Wegener-Bergeron-Findeisen process exist within one of these mixed-phase microstructures.

  20. Aerosol meteorology of Maritime Continent for the 2012 7SEAS southwest monsoon intensive study - Part 2: Philippine receptor observations of fine-scale aerosol behavior

    Science.gov (United States)

    Reid, Jeffrey S.; Lagrosas, Nofel D.; Jonsson, Haflidi H.; Reid, Elizabeth A.; Atwood, Samuel A.; Boyd, Thomas J.; Ghate, Virendra P.; Xian, Peng; Posselt, Derek J.; Simpas, James B.; Uy, Sherdon N.; Zaiger, Kimo; Blake, Donald R.; Bucholtz, Anthony; Campbell, James R.; Chew, Boon Ning; Cliff, Steven S.; Holben, Brent N.; Holz, Robert E.; Hyer, Edward J.; Kreidenweis, Sonia M.; Kuciauskas, Arunas P.; Lolli, Simone; Oo, Min; Perry, Kevin D.; Salinas, Santo V.; Sessions, Walter R.; Smirnov, Alexander; Walker, Annette L.; Wang, Qing; Yu, Liya; Zhang, Jianglong; Zhao, Yongjing

    2016-11-01

    The largest 7 Southeast Asian Studies (7SEAS) operations period within the Maritime Continent (MC) occurred in the August-September 2012 biomass burning season. Data included were observations aboard the M/Y Vasco, dispatched to the Palawan Archipelago and Sulu Sea of the Philippines for September 2012. At these locations, the Vasco observed MC smoke and pollution entering the southwest monsoon (SWM) monsoonal trough. Here we describe the research cruise findings and the finer-scale aerosol meteorology of this convectively active region. This 2012 cruise complemented a 2-week cruise in 2011 and was generally consistent with previous findings in terms of how smoke emission and transport related to monsoonal flows, tropical cyclones (TC), and the covariance between smoke transport events and the atmosphere's thermodynamic structure. Biomass burning plumes were usually mixed with significant amounts of anthropogenic pollution. Also key to aerosol behavior were squall lines and cold pools propagating across the South China Sea (SCS) and scavenging aerosol particles in their path. However, the 2012 cruise showed much higher modulation in aerosol frequency than its 2011 counterpart. Whereas in 2011 large synoptic-scale aerosol events transported high concentrations of smoke into the Philippines over days, in 2012 measured aerosol events exhibited a much shorter-term variation, sometimes only 3-12 h. Strong monsoonal flow reversals were also experienced in 2012. Nucleation events in cleaner and polluted conditions, as well as in urban plumes, were observed. Perhaps most interestingly, several cases of squall lines preceding major aerosol events were observed, as opposed to 2011 observations where these lines largely scavenged aerosol particles from the marine boundary layer. Combined, these observations indicate pockets of high and low particle counts that are not uncommon in the region. These perturbations are difficult to observe by satellite and very difficult to model

  1. Aerosol meteorology of Maritime Continent for the 2012 7SEAS southwest monsoon intensive study – Part 2: Philippine receptor observations of fine-scale aerosol behavior

    Directory of Open Access Journals (Sweden)

    J. S. Reid

    2016-11-01

    Full Text Available The largest 7 Southeast Asian Studies (7SEAS operations period within the Maritime Continent (MC occurred in the August–September 2012 biomass burning season. Data included were observations aboard the M/Y Vasco, dispatched to the Palawan Archipelago and Sulu Sea of the Philippines for September 2012. At these locations, the Vasco observed MC smoke and pollution entering the southwest monsoon (SWM monsoonal trough. Here we describe the research cruise findings and the finer-scale aerosol meteorology of this convectively active region. This 2012 cruise complemented a 2-week cruise in 2011 and was generally consistent with previous findings in terms of how smoke emission and transport related to monsoonal flows, tropical cyclones (TC, and the covariance between smoke transport events and the atmosphere's thermodynamic structure. Biomass burning plumes were usually mixed with significant amounts of anthropogenic pollution. Also key to aerosol behavior were squall lines and cold pools propagating across the South China Sea (SCS and scavenging aerosol particles in their path. However, the 2012 cruise showed much higher modulation in aerosol frequency than its 2011 counterpart. Whereas in 2011 large synoptic-scale aerosol events transported high concentrations of smoke into the Philippines over days, in 2012 measured aerosol events exhibited a much shorter-term variation, sometimes only 3–12 h. Strong monsoonal flow reversals were also experienced in 2012. Nucleation events in cleaner and polluted conditions, as well as in urban plumes, were observed. Perhaps most interestingly, several cases of squall lines preceding major aerosol events were observed, as opposed to 2011 observations where these lines largely scavenged aerosol particles from the marine boundary layer. Combined, these observations indicate pockets of high and low particle counts that are not uncommon in the region. These perturbations are difficult to observe by satellite and

  2. Aerosol Meteorology of Maritime Continent for the 2012 7SEAS Southwest Monsoon Intensive Study - Part 2: Philippine Receptor Observations of Fine-Scale Aerosol Behavior

    Science.gov (United States)

    Reid, Jeffrey S.; Lagrosas, Nofel D.; Jonsson, Haflidi H.; Reid, Elizabeth A.; Atwood, Samuel A.; Boyd, Thomas J.; Ghate, Virendra P.; Xian, Peng; Posselt, Derek J.; Simpas, James B.; hide

    2016-01-01

    The largest 7 Southeast Asian Studies (7SEAS) operations period within the Maritime Continent (MC) occurred in the August-September 2012 biomass burning season. Data included were observations aboard the MY Vasco, dispatched to the Palawan Archipelago and Sulu Sea of the Philippines for September 2012. At these locations, the Vasco observed MC smoke and pollution entering the southwest monsoon (SWM) monsoonal trough. Here we describe the research cruise findings and the finer-scale aerosol meteorology of this convectively active region. This 2012 cruise complemented a 2-week cruise in 2011 and was generally consistent with previous findings in terms of how smoke emission and transport related to monsoonal flows, tropical cyclones (TC), and the covariance between smoke transport events and the atmosphere's thermodynamic structure. Biomass burning plumes were usually mixed with significant amounts of anthropogenic pollution. Also key to aerosol behavior were squall lines and cold pools propagating across the South China Sea (SCS) and scavenging aerosol particles in their path. However, the 2012 cruise showed much higher modulation in aerosol frequency than its 2011 counterpart. Whereas in 2011 large synoptic-scale aerosol events transported high concentrations of smoke into the Philippines over days, in 2012 measured aerosol events exhibited a much shorter-term variation, sometimes only 312h. Strong monsoonal flow reversals were also experienced in 2012. Nucleation events in cleaner and polluted conditions, as well as in urban plumes, were observed. Perhaps most interestingly, several cases of squall lines preceding major aerosol events were observed, as opposed to 2011 observations where these lines largely scavenged aerosol particles from the marine boundary layer. Combined, these observations indicate pockets of high and low particle counts that are not uncommon in the region. These perturbations are difficult to observe by satellite and very difficult to model

  3. Aerosol meteorology of Maritime Continent for the 2012 7SEAS southwest monsoon intensive study – Part 2: Philippine receptor observations of fine-scale aerosol behavior

    Energy Technology Data Exchange (ETDEWEB)

    Reid, Jeffrey S.; Lagrosas, Nofel D.; Jonsson, Haflidi H.; Reid, Elizabeth A.; Atwood, Samuel A.; Boyd, Thomas J.; Ghate, Virendra P.; Xian, Peng; Posselt, Derek J.; Simpas, James B.; Uy, Sherdon N.; Zaiger, Kimo; Blake, Donald R.; Bucholtz, Anthony; Campbell, James R.; Chew, Boon Ning; Cliff, Steven S.; Holben, Brent N.; Holz, Robert E.; Hyer, Edward J.; Kreidenweis, Sonia M.; Kuciauskas, Arunas P.; Lolli, Simone; Oo, Min; Perry, Kevin D.; Salinas, Santo V.; Sessions, Walter R.; Smirnov, Alexander; Walker, Annette L.; Wang, Qing; Yu, Liya; Zhang, Jianglong; Zhao, Yongjing

    2016-01-01

    The largest 7 Southeast Asian Studies (7SEAS) operations period within the Maritime Continent (MC) occurred in the August–September 2012 biomass burning season. Data included were observations aboard the M/Y Vasco, dispatched to the Palawan Archipelago and Sulu Sea of the Philippines for September 2012. At these locations, the Vasco observed MC smoke and pollution entering the southwest monsoon (SWM) monsoonal trough. Here we describe the research cruise findings and the finer-scale aerosol meteorology of this convectively active region. This 2012 cruise complemented a 2-week cruise in 2011 and was generally consistent with previous findings in terms of how smoke emission and transport related to monsoonal flows, tropical cyclones (TC), and the covariance between smoke transport events and the atmosphere's thermodynamic structure. Biomass burning plumes were usually mixed with significant amounts of anthropogenic pollution. Also key to aerosol behavior were squall lines and cold pools propagating across the South China Sea (SCS) and scavenging aerosol particles in their path. However, the 2012 cruise showed much higher modulation in aerosol frequency than its 2011 counterpart. Whereas in 2011 large synoptic-scale aerosol events transported high concentrations of smoke into the Philippines over days, in 2012 measured aerosol events exhibited a much shorter-term variation, sometimes only 3$-$12 h. Strong monsoonal flow reversals were also experienced in 2012. Nucleation events in cleaner and polluted conditions, as well as in urban plumes, were observed. Perhaps most interestingly, several cases of squall lines preceding major aerosol events were observed, as opposed to 2011 observations where these lines largely scavenged aerosol particles from the marine boundary layer. Combined, these observations indicate pockets of high and low particle counts that are not uncommon in the region. These perturbations are difficult to observe by satellite

  4. Maritime Laser Scanning as the Source for Spatial Data

    Directory of Open Access Journals (Sweden)

    Szulwic Jakub

    2015-12-01

    Full Text Available The rapid development of scanning technology, especially mobile scanning, gives the possibility to collect spatial data coming from maritime measurement platforms and autonomous manned or unmanned vehicles. Presented solution is derived from the mobile scanning. However we should keep in mind that the specificity of laser scanning at sea and processing collected data should be in the form acceptable in Geographical Information Systems, especially typical for the maritime needs. At the same time we should be aware that data coming from maritime mobile scanning constitutes a new approach to the describing of maritime environment and brings a new perspective that is completely different than air and terrestrial scanning.

  5. An overview of maritime archaeological studies in India

    Digital Repository Service at National Institute of Oceanography (India)

    Tripati, S.

    stream_size 66180 stream_content_type text/plain stream_name Maritime_contacts_of_the_past_2015_729.pdf.txt stream_source_info Maritime_contacts_of_the_past_2015_729.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset...=UTF-8 AN OVERVIEW OF MARITIME ARCHAEOLOGICAL STUDIES IN INDIA 729An overview of maritime archaeological studies in India Sila Tripati, CSIR-National Institute of Oceanography, Goa, India Trade and cultural contacts among the people...

  6. Anvil Productivities of Tropical Deep Convective Clusters and Their Regional Differences

    Directory of Open Access Journals (Sweden)

    Deng Min

    2016-01-01

    The total anvil clouds detrained from convection counts for 0.4 to 0.8 of the cluster horizontal scale, 0.2 to 0.6 of the cluster cross section volume, and 0.05 to 0.20 of the cluster ice mass, depending on the cluster scales and height. There are two main detrainment layers. When the convective clusters is less than about 100 km, the anvil clouds are mainly detrained at about 6-8 km with a spreading ratio (ratio of maximum cluster width to convection rainy core width less than 1.5. When convective clusters becomes 100 km or wider, it reaches the dominate detrainment layer at about 12 km, the detrainment index increase from 2 to more 6. Among 8 regions, convection clusters in MA produce the most anvil volume fraction. The more the ice mass is pumped upward in the anvil clouds till clusters are about 500 km wider. Nevertheless, the anvil ice mass pumped above 15 km is less than 0.1% of the total ice mass in the convective cluster.

  7. Research on risk assessment for maritime transport of radioactive materials. Preparation of maritime accident data for risk assessment

    International Nuclear Information System (INIS)

    Odano, Naoteru; Sawada, Ken-ichi; Mochiduki, Hiromitsu; Hirao, Yoshihiro; Asami, Mitsufumi

    2010-01-01

    Maritime transport of radioactive materials has been playing an important role in the nuclear fuel cycle in Japan. Due to recent increase of transported radioactive materials and diversification of transport packages with enlargement of nuclear research, development and utilization, safety securement for maritime transport of radioactive materials is one of important issues in the nuclear fuel cycle. Based squarely on the current circumstances, this paper summarizes discussion on importance of utilization of results of risk assessment for maritime transport of radioactive materials. A plan for development of comprehensive methodology to assess risks in maritime transport of radioactive materials is also described. Preparations of database of maritime accident to be necessary for risk assessment are also summarized. The prepared data could be utilized for future quantitative risk assessment, such as the event trees and fault trees analyses, for maritime transport of radioactive materials. The frequency of severe accident that the package might be damaged is also estimated using prepared data. (author)

  8. Maritime Security Fleet: Factors to Consider before Deciding to Select Participants Competitively

    National Research Council Canada - National Science Library

    1997-01-01

    The Maritime Security Act established the Maritime Security Fleet (MSF) program, authorizing MARAD to enter into agreements with maritime shipping companies to provide DOD access to commercial vessels operating under U.S...

  9. Effect of Policy Analysis on Indonesia’s Maritime Cluster Development Using System Dynamics Modeling

    Science.gov (United States)

    Nursyamsi, A.; Moeis, A. O.; Komarudin

    2018-03-01

    As an archipelago with two third of its territory consist of water, Indonesia should address more attention to its maritime industry development. One of the catalyst to fasten the maritime industry growth is by developing a maritime cluster. The purpose of this research is to gain understanding of the effect if Indonesia implement maritime cluster policy to the growth of maritime economic and its role to enhance the maritime cluster performance, hence enhancing Indonesia’s maritime industry as well. The result of the constructed system dynamic model simulation shows that with the effect of maritime cluster, the growth of employment rate and maritime economic is much bigger that the business as usual case exponentially. The result implies that the government should act fast to form a legitimate cluster maritime organizer institution so that there will be a synergize, sustainable, and positive maritime cluster environment that will benefit the performance of Indonesia’s maritime industry.

  10. 76 FR 55732 - Public Listening Sessions Regarding the Maritime Administration's Panama Canal Expansion Study...

    Science.gov (United States)

    2011-09-08

    ... DEPARTMENT OF TRANSPORTATION Maritime Administration Public Listening Sessions Regarding the Maritime Administration's Panama Canal Expansion Study and the America's Marine Highway Program AGENCY: Maritime Administration, DOT. ACTION: Notice. SUMMARY: The purpose of this notice is to announce a series...

  11. Mobility and Cloud: Operating in Intermittent, Austere Network Conditions

    Science.gov (United States)

    2014-09-01

    limited DSC Digital Selective Calling EC2 Elastic Compute Cloud ECM electronic countermeasure EMIO Expanded Maritime Interdiction Operations ENDA...to a theoretical range of approximately 300 nautical miles (nm). The downside is that it is not electronic countermeasure (ECM)-resistant. 7 4...operator. For CMG, the streaming of video using the commercial video conferencing software Skype was used. High frame rate is important for good gaming

  12. Convection heat transfer

    CERN Document Server

    Bejan, Adrian

    2013-01-01

    Written by an internationally recognized authority on heat transfer and thermodynamics, this second edition of Convection Heat Transfer contains new and updated problems and examples reflecting real-world research and applications, including heat exchanger design. Teaching not only structure but also technique, the book begins with the simplest problem solving method (scale analysis), and moves on to progressively more advanced and exact methods (integral method, self similarity, asymptotic behavior). A solutions manual is available for all problems and exercises.

  13. Prognostic cloud water in the Los Alamos general circulation model

    International Nuclear Information System (INIS)

    Kristjansson, J.E.; Kao, C.Y.J.

    1994-01-01

    Most of today's general circulation models (GCMs) have a greatly simplified treatment of condensation and clouds. Recent observational studies of the earth's radiation budget have suggested cloud-related feedback mechanisms to be of tremendous importance for the issue of global change. Thus, an urgent need for improvements in the treatment of clouds in GCMs has arisen, especially as the clouds relate to radiation. In this paper, we investigate the effects of introducing prognostic cloud water into the Los Alamos GCM. The cloud water field, produced by both stratiform and convective condensation, is subject to 3-dimensional advection and vertical diffusion. The cloud water enters the radiation calculations through the longwave emissivity calculations. Results from several sensitivity simulations show that realistic water and precipitation fields can be obtained with the applied method. Comparisons with observations show that the most realistic results are obtained when more sophisticated schemes for moist convection are introduced at the same time. The model's cold bias is reduced and the zonal winds becomes stronger because of more realistic tropical convection

  14. Concepts of magnetospheric convection

    International Nuclear Information System (INIS)

    Vasyliunas, V.M.

    1975-01-01

    Magnetospheric physics, which grew out of attempts to understand the space environment of the Earth, is becoming increasingly applicable to other systems in the Universe. Among the planets, in addition to the Earth, Jupiter, Mercury, Mars and (in a somewhat different way) Venus are now known to have magnetospheres. The magnetospheres of pulsars have been regarded as an essential part of the pulsar phenomenon. Other astrophysical systems, such as supernova remnant shells or magnetic stars and binary star systems, may be describable as magnetospheres. The major concepts of magnetospheric physics thus need to be formulated in a general way not restricted to the geophysical context in which they may have originated. Magnetospheric convection has been one of the most important and fruitful concepts in the study of the Earth's magnetosphere. This paper describes the basic theoretical notions of convection in a manner applicable to magnetospheres generally and discusses the relative importance of convective corotational motions, with particular reference to the comparison of the Earth and Jupiter. (Auth.)

  15. Heating-insensitive scale increase caused by convective precipitation

    Science.gov (United States)

    Haerter, Jan; Moseley, Christopher; Berg, Peter

    2017-04-01

    The origin of intense convective extremes and their unusual temperature dependence has recently challenged traditional thermodynamic arguments, based on the Clausius-Clapeyron relation. In a sequence of studies (Lenderink and v. Mejgaard, Nat Geosc, 2008; Berg, Haerter, Moseley, Nat Geosc, 2013; and Moseley, Hohenegger, Berg, Haerter, Nat Geosc, 2016) the argument of convective-type precipitation overcoming the 7%/K increase in extremes by dynamical, rather than thermodynamic, processes has been promoted. How can the role of dynamical processes be approached for precipitating convective cloud? One-phase, non-precipitating Rayleigh-Bénard convection is a classical problem in complex systems science. When a fluid between two horizontal plates is sufficiently heated from below, convective rolls spontaneously form. In shallow, non-precipitating atmospheric convection, rolls are also known to form under specific conditions, with horizontal scales roughly proportional to the boundary layer height. Here we explore within idealized large-eddy simulations, how the scale of convection is modified, when precipitation sets in and intensifies in the course of diurnal solar heating. Before onset of precipitation, Bénard cells with relatively constant diameter form, roughly on the scale of the atmospheric boundary layer. We find that the onset of precipitation then signals an approximately linear (in time) increase in horizontal scale. This scale increase progresses at a speed which is rather insensitive to changes in surface temperature or changes in the rate at which boundary conditions change, hinting at spatial characteristics, rather than temperature, as a possible control on spatial scales of convection. When exploring the depth of spatial correlations, we find that precipitation onset causes a sudden disruption of order and a subsequent complete disintegration of organization —until precipitation eventually ceases. Returning to the initial question of convective

  16. The effect of clouds on the earth's solar and infrared radiation budgets

    Science.gov (United States)

    Herman, G. F.; Wu, M.-L. C.; Johnson, W. T.

    1980-01-01

    The effect of global cloudiness on the solar and infrared components of the earth's radiation balance is studied in general circulation model experiments. A wintertime simulation is conducted in which the cloud radiative transfer calculations use realistic cloud optical properties and are fully interactive with model-generated cloudiness. This simulation is compared to others in which the clouds are alternatively non-interactive with respect to the solar or thermal radiation calculations. Other cloud processes (formation, latent heat release, precipitation, vertical mixing) were accurately simulated in these experiments. It is concluded that on a global basis clouds increase the global radiation balance by 40 W/sq m by absorbing longwave radiation, but decrease it by 56 W/sq m by reflecting solar radiation to space. The net cloud effect is therefore a reduction of the radiation balance by 16 W/sq m, and is dominated by the cloud albedo effect. Changes in cloud frequency and distribution and in atmospheric and land temperatures are also reported for the control and for the non-interactive simulations. In general, removal of the clouds' infrared absorption cools the atmosphere and causes additional cloudiness to occur, while removal of the clouds' solar radiative properties warms the atmosphere and causes fewer clouds to form. It is suggested that layered clouds and convective clouds over water enter the climate system as positive feedback components, while convective clouds over land enter as negative components.

  17. Convective and large-scale mass flux profiles over tropical oceans determined from synergistic analysis of a suite of satellite observations

    Science.gov (United States)

    Masunaga, Hirohiko; Luo, Zhengzhao Johnny

    2016-07-01

    A new, satellite-based methodology is developed to evaluate convective mass flux and large-scale total mass flux. To derive the convective mass flux, candidate profiles of in-cloud vertical velocity are first constructed with a simple plume model under the constraint of ambient sounding and then narrowed down to the solution that matches satellite-derived cloud top buoyancy. Meanwhile, the large-scale total mass flux is provided separately from satellite soundings by a method developed previously. All satellite snapshots are sorted into a composite time series that delineates the evolution of a vigorous and organized convective system. Principal findings are the following. First, convective mass flux is modulated primarily by convective cloud cover, with the intensity of individual convection being less variable over time. Second, convective mass flux dominates the total mass flux only during the early hours of the convective evolution; as convective system matures, a residual mass flux builds up in the mass flux balance that is reminiscent of stratiform dynamics. The method developed in this study is expected to be of unique utility for future observational diagnosis of tropical convective dynamics and for evaluation of global climate model cumulus parameterizations in a global sense.

  18. Regional climate projection of the Maritime Continent using the MIT Regional Climate Model

    Science.gov (United States)

    IM, E. S.; Eltahir, E. A. B.

    2014-12-01

    Given that warming of the climate system is unequivocal (IPCC AR5), accurate assessment of future climate is essential to understand the impact of climate change due to global warming. Modelling the climate change of the Maritime Continent is particularly challenge, showing a high degree of uncertainty. Compared to other regions, model agreement of future projections in response to anthropogenic emission forcings is much less. Furthermore, the spatial and temporal behaviors of climate projections seem to vary significantly due to a complex geographical condition and a wide range of scale interactions. For the fine-scale climate information (27 km) suitable for representing the complexity of climate change over the Maritime Continent, dynamical downscaling is performed using the MIT regional climate model (MRCM) during two thirty-year period for reference (1970-1999) and future (2070-2099) climate. Initial and boundary conditions are provided by Community Earth System Model (CESM) simulations under the emission scenarios projected by MIT Integrated Global System Model (IGSM). Changes in mean climate as well as the frequency and intensity of extreme climate events are investigated at various temporal and spatial scales. Our analysis is primarily centered on the different behavior of changes in convective and large-scale precipitation over land vs. ocean during dry vs. wet season. In addition, we attempt to find the added value to downscaled results over the Maritime Continent through the comparison between MRCM and CESM projection. Acknowledgements.This research was supported by the National Research Foundation Singapore through the Singapore MIT Alliance for Research and Technology's Center for Environmental Sensing and Modeling interdisciplinary research program.

  19. Evaluation of the sensitivity of the Amazonian diurnal cycle to convective intensity in reanalyses

    Science.gov (United States)

    Itterly, Kyle F.; Taylor, Patrick C.

    2017-02-01

    Model parameterizations of tropical deep convection are unable to reproduce the observed diurnal and spatial variability of convection in the Amazon, which contributes to climatological biases in the water cycle and energy budget. Convective intensity regimes are defined using percentiles of daily minimum 3-hourly averaged outgoing longwave radiation (OLR) from Clouds and the Earth's Radiant Energy System (CERES). This study compares the observed spatial variability of convective diurnal cycle statistics for each regime to MERRA-2 and ERA-Interim (ERA) reanalysis data sets. Composite diurnal cycle statistics are computed for daytime hours (06:00-21:00 local time) in the wet season (December-January-February). MERRA-2 matches observations more closely than ERA for domain averaged composite diurnal statistics—specifically precipitation. However, ERA reproduces mesoscale features of OLR and precipitation phase associated with topography and the propagation of the coastal squall line. Both reanalysis models are shown to underestimate extreme convection.

  20. Comprehensive Maritime Awareness (CMA) - Joint Capabilities Technology Demonstration (JCTD), FY 06-09

    National Research Council Canada - National Science Library

    Dwyer, Chris

    2006-01-01

    ...) vision is to share maritime shipping information and tracks throughout the world to deter use of commercial maritime shipping for terrorism, WMD proliferation, drugs, piracy, and human trafficking...

  1. a Test to Prove Cloud Whitening THEORY!

    Science.gov (United States)

    Buttram, J. W.

    2011-12-01

    Climate science researchers believe our planet can possibly tolerate twice the present carbon dioxide levels with no upwards temperature change, IF we could increase the amount of energy reflected back out into space by about 2.0%. (c)Cloudtec basically alters a blend of seawater and applies heat derived from magma to it at a temperature exceeding 2,000 degrees F. The interaction of seawater and magma displaces the oxygen, causing the volume of water to vaporize and expand over 4,000 times - transforming billions of tons of seawater into thousands of cubic miles of white, maritime, stratocumulus clouds to reflect the incident Sun's rays back out into space. A 6 month test to prove Cloud Whitening Theory will cost 6 million dollars. (No profit added.) This study will enable everyone on the planet with a computer the transparency to use satellite imagery and check out for themselves - if and when Cloud Whitening is occurring. If Cloud Whitening Theory is validated, (c)Cloudtec's innovation can strategically create the clouds we need to reflect the Sun's rays back out into space and help neutralize the projected 3.6 degrees F rise in temperature. Based on reasonable calculations of anthropogenic global warming: this one move alone would be comparable to slashing global carbon dioxide emissions by over 60% over the next 40 years.

  2. The Roles of Convection Parameterization in the Formation of Double ITCZ Syndrome in the NCAR CESM: I. Atmospheric Processes

    Science.gov (United States)

    Song, Xiaoliang; Zhang, Guang J.

    2018-03-01

    Several improvements are implemented in the Zhang-McFarlane (ZM) convection scheme to investigate the roles of convection parameterization in the formation of double intertropical convergence zone (ITCZ) bias in the NCAR CESM1.2.1. It is shown that the prominent double ITCZ biases of precipitation, sea surface temperature (SST), and wind stress in the standard CESM1.2.1 are largely eliminated in all seasons with the use of these improvements in convection scheme. This study for the first time demonstrates that the modifications of convection scheme can eliminate the double ITCZ biases in all seasons, including boreal winter and spring. Further analysis shows that the elimination of the double ITCZ bias is achieved not by improving other possible contributors, such as stratus cloud bias off the west coast of South America and cloud/radiation biases over the Southern Ocean, but by modifying the convection scheme itself. This study demonstrates that convection scheme is the primary contributor to the double ITCZ bias in the CESM1.2.1, and provides a possible solution to the long-standing double ITCZ problem. The atmospheric model simulations forced by observed SST show that the original ZM convection scheme tends to produce double ITCZ bias in high SST scenario, while the modified convection scheme does not. The impact of changes in each core component of convection scheme on the double ITCZ bias in atmospheric model is identified and further investigated.

  3. Soft Clouding

    DEFF Research Database (Denmark)

    Søndergaard, Morten; Markussen, Thomas; Wetton, Barnabas

    2012-01-01

    Soft Clouding is a blended concept, which describes the aim of a collaborative and transdisciplinary project. The concept is a metaphor implying a blend of cognitive, embodied interaction and semantic web. Furthermore, it is a metaphor describing our attempt of curating a new semantics of sound...... archiving. The Soft Clouding Project is part of LARM - a major infrastructure combining research in and access to sound and radio archives in Denmark. In 2012 the LARM infrastructure will consist of more than 1 million hours of radio, combined with metadata who describes the content. The idea is to analyse...... the concept of ‘infrastructure’ and ‘interface’ on a creative play with the fundamentals of LARM (and any sound archive situation combining many kinds and layers of data and sources). This paper will present and discuss the Soft clouding project from the perspective of the three practices and competencies...

  4. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    Directory of Open Access Journals (Sweden)

    B. Croft

    2012-11-01

    Full Text Available The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model. To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model.

    A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude.

    Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition, depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme. Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold. However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction

  5. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    Science.gov (United States)

    Croft, B.; Pierce, J. R.; Martin, R. V.; Hoose, C.; Lohmann, U.

    2012-11-01

    The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM) under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model). To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model. A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD) is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude. Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition), depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme). Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold). However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction scheme) since nearly all

  6. When Did the Swahili Become Maritime?

    Science.gov (United States)

    Fleisher, Jeffrey; Lane, Paul; LaViolette, Adria; Horton, Mark; Pollard, Edward; Quintana Morales, Eréndira; Vernet, Thomas; Christie, Annalisa; Wynne-Jones, Stephanie

    2015-03-01

    In this article, we examine an assumption about the historic Swahili of the eastern African coast: that they were a maritime society from their beginnings in the first millennium C.E. Based on historical and archaeological data, we suggest that, despite their proximity to and use of the sea, the level of maritimity of Swahili society increased greatly over time and was only fully realized in the early second millennium C.E. Drawing on recent theorizing from other areas of the world about maritimity as well as research on the Swahili, we discuss three arenas that distinguish first- and second-millennium coastal society in terms of their maritime orientation. These are variability and discontinuity in settlement location and permanence; evidence of increased engagement with the sea through fishing and sailing technology; and specialized architectural developments involving port facilities, mosques, and houses. The implications of this study are that we must move beyond coastal location in determining maritimity; consider how the sea and its products were part of social life; and assess whether the marine environment actively influences and is influenced by broader patterns of sociocultural organization, practice, and belief within Swahili and other societies. [ maritime, fishing and sailing, long-distance trade, Swahili, eastern Africa ]. En este artículo, evaluamos la hipótesis de que los pueblos Swahili de la costa oriental africana fueron una sociedad marítima a partir del primer milenio E.C. Basados en información histórica y arqueológica, proponemos que la asociación de la sociedad Swahili con el mar incrementó considerablemente con el tiempo y se manifestó de una forma significativa particularmente desde principios del segundo milenio E.C. Utilizando teorías recientes sobre maritimidad en otras áreas del mundo, así como investigaciones sobre los Swahili, discutimos tres temas que marcan las diferencias del nivel de orientación marítima de esta

  7. Cloud Chamber

    DEFF Research Database (Denmark)

    Gfader, Verina

    Cloud Chamber takes its roots in a performance project, titled The Guests 做东, devised by Verina Gfader for the 11th Shanghai Biennale, ‘Why Not Ask Again: Arguments, Counter-arguments, and Stories’. Departing from the inclusion of the biennale audience to write a future folk tale, Cloud Chamber......: fiction and translation and translation through time; post literacy; world picturing-world typing; and cartographic entanglements and expressions of subjectivity; through the lens a social imaginary of worlding or cosmological quest. Art at its core? Contributions by Nikos Papastergiadis, Rebecca Carson...

  8. POSSIBILITIES OF UAS FOR MARITIME MONITORING

    Directory of Open Access Journals (Sweden)

    A. Klimkowska

    2016-06-01

    Full Text Available In the last few years, Unmanned Aircraft Systems (UAS have become more important and its use for different application is appreciated. At the beginning UAS were used for military purposes. These successful applications initiated interest among researchers to find uses of UAS for civilian purposes, as they are alternative to both manned and satellite systems in acquiring high-resolution remote sensing data at lower cost while long flight duration. As UAS are built from many components such as unmanned aerial vehicle (UAV, sensing payloads, communication systems, ground control stations, recovery and launch equipment, and supporting equipment, knowledge about its functionality and characteristics is crucial for missions. Therefore, finding appropriate configuration of all elements to fulfill requirements of the mission is a very difficult, yet important task. UAS may be used in various maritime applications such as ship detection, red tide detection and monitoring, border patrol, tracking of pollution at sea and hurricane monitoring just to mention few. One of the greatest advantages of UAV is their ability to fly over dangerous and hazardous areas, where sending manned aircraft could be risky for a crew. In this article brief description of aerial unmanned system components is introduced. Firstly characteristics of unmanned aerial vehicles are presented, it continues with introducing inertial navigation system, communication systems, sensing payloads, ground control stations, and ground and recovery equipment. Next part introduces some examples of UAS for maritime applications. This is followed by suggestions of key indicators which should be taken into consideration while choosing UAS. Last part talks about configuration schemes of UAVs and sensor payloads suggested for some maritime applications.

  9. MARD – Maritime Academic Resource Database

    Directory of Open Access Journals (Sweden)

    Bogumil Laczynski

    2014-12-01

    Full Text Available IAMU (International Association of Maritime Universities was established fifteen years ago. For this moment IAMU content close to 60 Members Institution. One of the research activities in years 2012- 2014 was: preparing the algorithm for collect and analyze the necessary information and convert it into Matrix form. Both: IAMU MEMBERS INSTITUTION DATABASE and HUMAN RESOURCE DATABASE include comparison indicators such as academic degree, teaching subjects, qualifications, research experience and so on. In opinion of group of researchers new established database should be very useful and helpful in field of cooperation between IAMU Members Institutions.

  10. The effects of aerosols on precipitation and dimensions of subtropical clouds: a sensitivity study using a numerical cloud model

    Directory of Open Access Journals (Sweden)

    A. Teller

    2006-01-01

    Full Text Available Numerical experiments were carried out using the Tel-Aviv University 2-D cloud model to investigate the effects of increased concentrations of Cloud Condensation Nuclei (CCN, giant CCN (GCCN and Ice Nuclei (IN on the development of precipitation and cloud structure in mixed-phase sub-tropical convective clouds. In order to differentiate between the contribution of the aerosols and the meteorology, all simulations were conducted with the same meteorological conditions. The results show that under the same meteorological conditions, polluted clouds (with high CCN concentrations produce less precipitation than clean clouds (with low CCN concentrations, the initiation of precipitation is delayed and the lifetimes of the clouds are longer. GCCN enhance the total precipitation on the ground in polluted clouds but they have no noticeable effect on cleaner clouds. The increased rainfall due to GCCN is mainly a result of the increased graupel mass in the cloud, but it only partially offsets the decrease in rainfall due to pollution (increased CCN. The addition of more effective IN, such as mineral dust particles, reduces the total amount of precipitation on the ground. This reduction is more pronounced in clean clouds than in polluted ones. Polluted clouds reach higher altitudes and are wider than clean clouds and both produce wider clouds (anvils when more IN are introduced. Since under the same vertical sounding the polluted clouds produce less rain, more water vapor is left aloft after the rain stops. In our simulations about 3.5 times more water evaporates after the rain stops from the polluted cloud as compared to the clean cloud. The implication is that much more water vapor is transported from lower levels to the mid troposphere under polluted conditions, something that should be considered in climate models.

  11. Assumed Probability Density Functions for Shallow and Deep Convection

    Directory of Open Access Journals (Sweden)

    Steven K Krueger

    2010-10-01

    Full Text Available The assumed joint probability density function (PDF between vertical velocity and conserved temperature and total water scalars has been suggested to be a relatively computationally inexpensive and unified subgrid-scale (SGS parameterization for boundary layer clouds and turbulent moments. This paper analyzes the performance of five families of PDFs using large-eddy simulations of deep convection, shallow convection, and a transition from stratocumulus to trade wind cumulus. Three of the PDF families are based on the double Gaussian form and the remaining two are the single Gaussian and a Double Delta Function (analogous to a mass flux model. The assumed PDF method is tested for grid sizes as small as 0.4 km to as large as 204.8 km. In addition, studies are performed for PDF sensitivity to errors in the input moments and for how well the PDFs diagnose some higher-order moments. In general, the double Gaussian PDFs more accurately represent SGS cloud structure and turbulence moments in the boundary layer compared to the single Gaussian and Double Delta Function PDFs for the range of grid sizes tested. This is especially true for small SGS cloud fractions. While the most complex PDF, Lewellen-Yoh, better represents shallow convective cloud properties (cloud fraction and liquid water mixing ratio compared to the less complex Analytic Double Gaussian 1 PDF, there appears to be no advantage in implementing Lewellen-Yoh for deep convection. However, the Analytic Double Gaussian 1 PDF better represents the liquid water flux, is less sensitive to errors in the input moments, and diagnoses higher order moments more accurately. Between the Lewellen-Yoh and Analytic Double Gaussian 1 PDFs, it appears that neither family is distinctly better at representing cloudy layers. However, due to the reduced computational cost and fairly robust results, it appears that the Analytic Double Gaussian 1 PDF could be an ideal family for SGS cloud and turbulence

  12. Uncertainty in Fleet Renewal: A Case from Maritime Transportation

    DEFF Research Database (Denmark)

    Pantuso, Giovanni; Fagerholt, Kjetil; Wallace, Stein W.

    2016-01-01

    This paper addresses the fleet renewal problem and particularly the treatment of uncertainty in the maritime case. A stochastic programming model for the maritime fleet renewal problem is presented. The main contribution is that of assessing whether or not better decisions can be achieved by using...

  13. 75 FR 82039 - National Maritime Security Advisory Committee; Meeting

    Science.gov (United States)

    2010-12-29

    ... Security Advisory Committee (NMSAC) will meet in Washington, DC to discuss various issues relating to national maritime security. This meeting will be open to the public. DATES: The Committee will meet on... DEPARTMENT OF HOMELAND SECURITY Coast Guard [USCG-2010-1005] National Maritime Security Advisory...

  14. 75 FR 38536 - National Maritime Security Advisory Committee; Meeting

    Science.gov (United States)

    2010-07-02

    ... Security Advisory Committee (NMSAC) will meet in Washington, DC to discuss various issues relating to national maritime security. This meeting will be open to the public. DATES: The Committee will meet on... DEPARTMENT OF HOMELAND SECURITY Coast Guard [USCG-2010-0586] National Maritime Security Advisory...

  15. Maritime energy and security: Synergistic maximization or necessary tradeoffs?

    International Nuclear Information System (INIS)

    Nyman, Elizabeth

    2017-01-01

    Offshore energy is big business. The traditional source of maritime energy, offshore petroleum and gas, has been on the rise since a reliable method of extraction was discovered in the mid-20th century. Lately, it has been joined by offshore wind and tidal power as alternative “green” sources of maritime energy. Yet all of this has implications for maritime environmental regimes as well, as maritime energy extraction/generation can have a negative effect on the ocean environment. This paper considers two major questions surrounding maritime energy and environmental concerns. First, how and why do these two concerns, maritime energy and environmental protection, play against each other? Second, how can states both secure their energy and environmental securities in the maritime domain? Maximizing maritime energy output necessitates some environmental costs and vice versa, but these costs vary with the type of offshore energy technology used and with the extent to which states are willing to expend effort to protect both environmental and energy security. - Highlights: • Security is a complicated concept with several facets including energy and environmental issues. • Offshore energy contributes to energy supply but can have environmental and monitoring costs. • Understanding the contribution of offshore energy to security depends on which security facet is deemed most important.

  16. 32 CFR 537.19 - Demands arising from maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Demands arising from maritime claims. 537.19 Section 537.19 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS ON BEHALF OF THE UNITED STATES § 537.19 Demands arising from maritime claims. (a) It is...

  17. 32 CFR 537.18 - Settlement authority for maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Settlement authority for maritime claims. 537.18 Section 537.18 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS ON BEHALF OF THE UNITED STATES § 537.18 Settlement authority for maritime claims. (a) The...

  18. 77 FR 51817 - National Maritime Security Advisory Committee; Meeting

    Science.gov (United States)

    2012-08-27

    ... the information sharing efforts of the Coast Guard and DHS. (2) Cyber-Security. The Committee will... DEPARTMENT OF HOMELAND SECURITY Coast Guard [USCG-2012-0797] National Maritime Security Advisory...: The National Maritime Security Advisory Committee (NMSAC) will meet on September 11-12, 2012 in the...

  19. Atmospheric study of the impact of Borneo vortex and Madden-Julian oscillation over Western Indonesian maritime area

    Science.gov (United States)

    Saragih, R. M.; Fajarianti, R.; Winarso, P. A.

    2018-03-01

    During the Asian winter Monsoon (November-March), the Indonesia Maritime Continent is an area of deep convection. In that period, there is a synoptic scale disturbance over Northwest of Borneo Island called Borneo vortex. In addition to the impact of Asian Winter Monsoon, Madden-Julian Oscillation (MJO) also have an impact on deep convection during an active period. This study aims to study the impact of interaction Borneo vortex and MJO (during MJO active period in phase 3, 4 and 5) and rainfall condition over the western part of Indonesia Maritime Continent using compositing technique in the period of November-March 2015/2016. The parameters used to identify the incidence of Borneo vortex, MJO, and its interaction is vertical velocity. When MJO is active, Borneo vortex occurs most often in phase 5 and at least in phase 3. However, Borneo vortex occurs most often when the MJO is inactive. The interaction between Borneo vortex and MJO seems may affect not so much rainfall occurrence in the western part of IMC.

  20. Bidispersive-inclined convection

    Science.gov (United States)

    Mulone, Giuseppe; Straughan, Brian

    2016-01-01

    A model is presented for thermal convection in an inclined layer of porous material when the medium has a bidispersive structure. Thus, there are the usual macropores which are full of a fluid, but there are also a system of micropores full of the same fluid. The model we employ is a modification of the one proposed by Nield & Kuznetsov (2006 Int. J. Heat Mass Transf. 49, 3068–3074. (doi:10.1016/j.ijheatmasstransfer.2006.02.008)), although we consider a single temperature field only. PMID:27616934

  1. Fusing Multiple Satellite Datasets Toward Defining and Understanding Organized Convection

    Science.gov (United States)

    Elsaesser, G.; Del Genio, A. D.

    2017-12-01

    parameterizing organized convection in the GISS GCM. GCMs must make/sustain the right heating profile at the right time, which requires observations-based understanding of such distinctions. Such knowledge is important for simulating and understanding the deep convective contribution to cloud feedback in a changing climate.

  2. Human Factors and Safety Culture in Maritime Safety (revised

    Directory of Open Access Journals (Sweden)

    Heinz Peter Berg

    2013-09-01

    Full Text Available As in every industry at risk, the human and organizational factors constitute the main stakes for maritime safety. Furthermore, several events at sea have been used to develop appropriate risk models. The investigation on maritime accidents is, nowadays, a very important tool to identify the problems related to human factor and can support accident prevention and the improvement of maritime safety. Part of this investigation should in future also be near misses. Operation of ships is full of regulations, instructions and guidelines also addressing human factors and safety culture to enhance safety. However, even though the roots of a safety culture have been established, there are still serious barriers to the breakthrough of the safety management. One of the most common deficiencies in the case of maritime transport is the respective monitoring and documentation usually lacking of adequacy and excellence. Nonetheless, the maritime area can be exemplified from other industries where activities are ongoing to foster and enhance safety culture.

  3. Cloud computing.

    Science.gov (United States)

    Wink, Diane M

    2012-01-01

    In this bimonthly series, the author examines how nurse educators can use Internet and Web-based technologies such as search, communication, and collaborative writing tools; social networking and social bookmarking sites; virtual worlds; and Web-based teaching and learning programs. This article describes how cloud computing can be used in nursing education.

  4. Cloud Computing

    Indian Academy of Sciences (India)

    IAS Admin

    2014-03-01

    Mar 1, 2014 ... There are several types of services available on a cloud. We describe .... CPU speed has been doubling every 18 months at constant cost. Besides this ... Plain text (e.g., email) may be read by anyone who is able to access it.

  5. Barrier Effect of the Indo-Pacific Maritime Continent on the MJO: Perspectives from Tracking MJO Precipitation

    Science.gov (United States)

    Zhang, C.; Ling, J.

    2016-12-01

    To advance the study of the barrier effect of the Indo-Pacific Maritime Continent (MC) on the MJO, we propose two criteria to judge explanations for this phenomenon. The first one is that such explanations should include specific features of the MC, namely, its intricate land-sea distributions and elevated terrains. The second is that they should include mechanisms for some MJO events to overcome the barrier effect as well as the barrier effect itself. Guided by these criteria, we have used a precipitation-tracking method to identify MJO events, distinguish those that propagate across the MC (MJO-C) from those that are blocked by the MC (MJO-B), and compare these two types of MJO events and their large-scale environments. The barrier effect cannot be explained in terms of the strength and horizontal scale or distributions of MJO convection as it approaches the MC from the Indian Ocean. A distinction between MJO-B and MJO-C is their ratios of precipitation over the sea vs. land in the MC. MJO events may propagate through the MC when their convection over the sea of the MC is sufficiently developed and dominates that over land. This may happen for two reasons. One is stronger precipitation over land that occurs before the arrival of MJO convection centers, which is assisted by greater low-level moisture flux convergence over the MC. This stronger "vanguard of precipitation" for MJO-C would make the ground wetter and thus reduce land-locked diurnal convection that has been proposed to be detrimental to MJO propagation through the MC. Another possible reason for the more vigorous development of MJO-C convection over the sea is higher SST in the MC before MJO convection centers enter the region.

  6. Definition of "banner clouds" based on time lapse movies

    Directory of Open Access Journals (Sweden)

    J. H. Schween

    2007-01-01

    Full Text Available Banner clouds appear on the leeward side of a mountain and resemble a banner or a flag. This article provides a comprehensive definition of "banner clouds". It is based primarily on an extensive collection of time lapse movies, but previous attempts at an explanation of this phenomenon are also taken into account. The following ingredients are considered essential: the cloud must be attached to the mountain but not appear on the windward side; the cloud must originate from condensation of water vapour contained in the air (rather than consist of blowing snow; the cloud must be persistent; and the cloud must not be of convective nature. The definition is illustrated and discussed with the help of still images and time lapse movies taken at Mount Zugspitze in the Bavarian Alps.

  7. Aerosol Effects on Instability, Circulations, Clouds, and Precipitation

    Directory of Open Access Journals (Sweden)

    Seoung-Soo Lee

    2014-01-01

    Full Text Available It is well known that increasing aerosol and associated changes in aerosol-cloud interactions and precipitation since industrialization have been playing an important role in climate change, but this role has not been well understood. This prevents us from predicting future climate with a good confidence. This review paper presents recent studies on the changes in the aerosol-cloud interactions and precipitation particularly in deep convective clouds. In addition, this review paper discusses how to improve our understanding of these changes by considering feedbacks among aerosol, cloud dynamics, cloud and its embedded circulations, and microphysics. Environmental instability basically determines the dynamic intensity of clouds and thus acts as one of the most important controls on these feedbacks. As a first step to the improvement of the understanding, this paper specifically elaborates on how to link the instability to the feedbacks.

  8. An Automated System to Quantify Convectively induced Aircraft encounters with Turbulence over Europe and North Atlantic

    Science.gov (United States)

    Meneguz, Elena; Turp, Debi; Wells, Helen

    2015-04-01

    It is well known that encounters with moderate or severe turbulence can lead to passenger injuries and incur high costs for airlines from compensation and litigation. As one of two World Area Forecast Centres (WAFCs), the Met Office has responsibility for forecasting en-route weather hazards worldwide for aviation above a height of 10,000 ft. Observations from commercial aircraft provide a basis for gaining a better understanding of turbulence and for improving turbulence forecasts through verification. However there is currently a lack of information regarding the possible cause of the observed turbulence, or whether the turbulence occurred within cloud. Such information would be invaluable for the development of forecasting techniques for particular types of turbulence and for forecast verification. Of all the possible sources of turbulence, convective activity is believed to be a major cause of turbulence. Its relative importance over the Europe and North Atlantic area has not been yet quantified in a systematic way: in this study, a new approach is developed to automate identification of turbulent encounters in the proximity of convective clouds. Observations of convection are provided from two independent sources: a surface based lightning network and satellite imagery. Lightning observations are taken from the Met Office Arrival Time Detections network (ATDnet). ATDnet has been designed to identify cloud-to-ground flashes over Europe but also detects (a smaller fraction of) strikes over the North Atlantic. Meteosat Second Generation (MSG) satellite products are used to identify convective clouds by applying a brightness temperature filtering technique. The morphological features of cold cloud tops are also investigated. The system is run for all in situ turbulence reports received from airlines for a total of 12 months during summer 2013 and 2014 for the domain of interest. Results of this preliminary short term climatological study show significant intra

  9. A cloud-ozone data product from Aura OMI and MLS satellite measurements

    Directory of Open Access Journals (Sweden)

    J. R. Ziemke

    2017-11-01

    Full Text Available Ozone within deep convective clouds is controlled by several factors involving photochemical reactions and transport. Gas-phase photochemical reactions and heterogeneous surface chemical reactions involving ice, water particles, and aerosols inside the clouds all contribute to the distribution and net production and loss of ozone. Ozone in clouds is also dependent on convective transport that carries low-troposphere/boundary-layer ozone and ozone precursors upward into the clouds. Characterizing ozone in thick clouds is an important step for quantifying relationships of ozone with tropospheric H2O, OH production, and cloud microphysics/transport properties. Although measuring ozone in deep convective clouds from either aircraft or balloon ozonesondes is largely impossible due to extreme meteorological conditions associated with these clouds, it is possible to estimate ozone in thick clouds using backscattered solar UV radiation measured by satellite instruments. Our study combines Aura Ozone Monitoring Instrument (OMI and Microwave Limb Sounder (MLS satellite measurements to generate a new research product of monthly-mean ozone concentrations in deep convective clouds between 30° S and 30° N for October 2004–April 2016. These measurements represent mean ozone concentration primarily in the upper levels of thick clouds and reveal key features of cloud ozone including: persistent low ozone concentrations in the tropical Pacific of  ∼ 10 ppbv or less; concentrations of up to 60 pphv or greater over landmass regions of South America, southern Africa, Australia, and India/east Asia; connections with tropical ENSO events; and intraseasonal/Madden–Julian oscillation variability. Analysis of OMI aerosol measurements suggests a cause and effect relation between boundary-layer pollution and elevated ozone inside thick clouds over landmass regions including southern Africa and India/east Asia.

  10. Maritime Electric Co. Ltd. annual report, 1991

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    Maritime Electric Company is a Canadian investor-owned electric utility based in Prince Edward Island. Established in 1918, the Company owns and operates a fully integrated system providing for the generation, transmission, and distribution of electricity throughout the Island. Maritime Electric operates generating plants in Charlottetown and Borden, and has an equity interest in NB Power's unit in Dalhousie, New Brunswick. Its 4,400 km distribution system and 560 km transmission system are linked to the mainland power grid by two submarine cables between the Island and the province of New Brunswick. This report describes the Company's operations, power production and sales for the year, with relevant statistical information. Financial statements are also included. In 1991 increases in operating revenue were lower than forecast due to the recession. Tight control of expenses, together with higher rates allowed a satisfactory rate of return. Earnings per share were $1.79 compared to $1.61 in 1990. Demand side management initiatives were enhanced, and a customer survey indicated satisfaction with service. Plant life extension programs continued at the Charlottetown generating station.

  11. Maritime Electric Co. Ltd. annual report, 1992

    International Nuclear Information System (INIS)

    1992-01-01

    Maritime Electric Company is a Canadian investor-owned electric utility based in Prince Edward Island. Established in 1918, the Company owns and operates a fully integrated system providing for the generation, transmission, and distribution of electricity throughout the Island. Maritime Electric operates generating plants in Charlottetown and Borden, and has an equity interest in NB Power's unit in Dalhousie, New Brunswick. Its 4,400 km distribution system and 560 km transmission system are linked to the mainland power grid by two submarine cables between the Island and the province of New Brunswick. This report describes the Company's operations, power production and sales for the year, with relevant statistical information. Financial statements are also included. In 1992 the Victoria Cross distribution substation was rebuilt. Earnings per share in 1992 were $1.85 compared with $1.79 in 1991. Demand side management initiatives were further enhanced and the plant life extension program continued at the Charlottetown Generating Plant. A ten year summary is included. 7 figs

  12. Maritime Electric Co. Ltd. annual report, 1991

    International Nuclear Information System (INIS)

    1991-01-01

    Maritime Electric Company is a Canadian investor-owned electric utility based in Prince Edward Island. Established in 1918, the Company owns and operates a fully integrated system providing for the generation, transmission, and distribution of electricity throughout the Island. Maritime Electric operates generating plants in Charlottetown and Borden, and has an equity interest in NB Power's unit in Dalhousie, New Brunswick. Its 4,400 km distribution system and 560 km transmission system are linked to the mainland power grid by two submarine cables between the Island and the province of New Brunswick. This report describes the Company's operations, power production and sales for the year, with relevant statistical information. Financial statements are also included. In 1991 increases in operating revenue were lower than forecast due to the recession. Tight control of expenses, together with higher rates allowed a satisfactory rate of return. Earnings per share were $1.79 compared to $1.61 in 1990. Demand side management initiatives were enhanced, and a customer survey indicated satisfaction with service. Plant life extension programs continued at the Charlottetown generating station

  13. Modeling of clouds and radiation for development of parameterizations for general circulation models

    International Nuclear Information System (INIS)

    Westphal, D.; Toon, B.; Jensen, E.; Kinne, S.; Ackerman, A.; Bergstrom, R.; Walker, A.

    1994-01-01

    Atmospheric Radiation Measurement (ARM) Program research at NASA Ames Research Center (ARC) includes radiative transfer modeling, cirrus cloud microphysics, and stratus cloud modeling. These efforts are designed to provide the basis for improving cloud and radiation parameterizations in our main effort: mesoscale cloud modeling. The range of non-convective cloud models used by the ARM modeling community can be crudely categorized based on the number of predicted hydrometers such as cloud water, ice water, rain, snow, graupel, etc. The simplest model has no predicted hydrometers and diagnoses the presence of clouds based on the predicted relative humidity. The vast majority of cloud models have two or more predictive bulk hydrometers and are termed either bulk water (BW) or size-resolving (SR) schemes. This study compares the various cloud models within the same dynamical framework, and compares results with observations rather than climate statistics

  14. Interactions between vegetation, atmospheric turbulence and clouds under a wide range of background wind conditions

    NARCIS (Netherlands)

    Sikma, M.; Ouwersloot, H.G.; Pedruzo-Bagazgoitia, X.; Heerwaarden, van C.C.; Vilà-Guerau de Arellano, J.

    2018-01-01

    The effects of plant responses to cumulus (Cu) cloud shading are studied from free convective to shear-driven boundary-layer conditions. By using a large-eddy simulation (LES) coupled to a plant physiology embedded land-surface submodel, we study the vegetation-cloud feedbacks for a wide range (44)

  15. Aerosol nucleation and growth in the TTL, due to tropical convection, during the ACTIVE campaign

    Science.gov (United States)

    Waddicor, D.; Vaughan, G.; Choularton, T.

    2009-04-01

    The Aerosol and Chemical Transport In tropical convection (ACTIVE) campaign took place between October 2005 and February 2006. This investigation involved the sampling of deep convective storms that occur in the Tropics; the campaign was based in Darwin, Northern Territory, Australia - the latter half of the campaign coincided with the monsoon season. A range of scientific equipment was used to sample the inflow and outflow air from these storms; of particular importance were the NERC Dornier (low-level) and ARA Egrett (high-level outflow) aircraft. The Dornier held a range of aerosol, particle and chemical detectors for the purpose of analysing the planetary boundary layer (PBL), in the vicinity of tropical convection. The Egrett contained detection instrumentation for a range of sizes of aerosol and cloud particles (2 Condensation Particle Counters (CPC), CAPS, CIP, CPI) in the storm outflow. This allowed a quantifiable measurement to be made of the effect of deep tropical convection on the aerosol population in the Tropical Tropopause Layer (TTL). The ACTIVE campaign found that there were large numbers of aerosol particles in the 10 - 100 nm (up to 25,000 /cm3 STP) and 100 - 1000 nm (up to 600 /cm3) size ranges. These values, in many instances, surpassed those found in the PBL. The higher levels of aerosol found in the TTL compared to the PBL could indicate that aerosol nucleation was occurring in the TTL as a direct result of convective activity. Furthermore, the Egrett aircraft found distinct boundaries between the high levels of aerosol, which were found in cloud free regions, and very low numbers of aerosol, which were found in the cloudy regions (storm anvil). The air masses were determined, from back trajectories, to have been through convective uplift and were formerly part of the anvil cloud. The cloudy regions would have contained high levels of entrapped precursor gases. Reduced nucleation and cloud particle scavenging of aerosol and gases would give a

  16. Aerosol microphysical and radiative effects on continental cloud ensembles

    Science.gov (United States)

    Wang, Yuan; Vogel, Jonathan M.; Lin, Yun; Pan, Bowen; Hu, Jiaxi; Liu, Yangang; Dong, Xiquan; Jiang, Jonathan H.; Yung, Yuk L.; Zhang, Renyi

    2018-02-01

    Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. In this study, an aerosol-aware WRF model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the US Southern Great Plains. Three simulated cloud ensembles include a low-pressure deep convective cloud system, a collection of less-precipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by several ground-based measurements. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not influence the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with a prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. The simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity (typically less than 2%) to aerosol perturbations, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type.

  17. Laboratory study of orographic cloud-like flow

    Science.gov (United States)

    Singh, Kanwar Nain; Sreenivas, K. R.

    2013-11-01

    Clouds are one of the major sources of uncertainty in climate prediction, listed in ``the most urgent scientific problems requiring attention'' IPCC. Also, convective clouds are of utmost importance to study the dynamics of tropical meteorology and therefore, play a key role in understanding monsoons. The present work is to study the dynamics of orographic clouds. Parameterization of these clouds will help in forecasting the precipitation accurately. Also, one could validate laboratory results from our study by actually measuring cloud development along a sloping terrain. In this context a planar buoyant turbulent wall jet is considered as an appropriate low order fluid-dynamical model for studying the turbulence and entrainment in orographic-clouds. Flow is volumetrically heated to mimic the latent heat release due to condensation in an actual cloud. This is the first step in studying the entrainment dynamics of the evolving orographic cloud. We are going to present some results on the cloud development using techniques that allows us to construct a 3-dimensional flow field at each instance and its development over the time. By combining velocity field from PIV and flow volume from PLIF at successive instances, we estimate the entrainment coefficient. Since the life-cycle of a cloud is determined by the entrainment of ambient air, these results could be extremely helpful in understanding the dynamics of the clouds. Detailed results will be presented at the conference.

  18. Evaluation of NCMRWF unified model vertical cloud structure with CloudSat over the Indian summer monsoon region

    Science.gov (United States)

    Jayakumar, A.; Mamgain, Ashu; Jisesh, A. S.; Mohandas, Saji; Rakhi, R.; Rajagopal, E. N.

    2016-05-01

    Representation of rainfall distribution and monsoon circulation in the high resolution versions of NCMRWF Unified model (NCUM-REG) for the short-range forecasting of extreme rainfall event is vastly dependent on the key factors such as vertical cloud distribution, convection and convection/cloud relationship in the model. Hence it is highly relevant to evaluate the vertical structure of cloud and precipitation of the model over the monsoon environment. In this regard, we utilized the synergy of the capabilities of CloudSat data for long observational period, by conditioning it for the synoptic situation of the model simulation period. Simulations were run at 4-km grid length with the convective parameterization effectively switched off and on. Since the sample of CloudSat overpasses through the monsoon domain is small, the aforementioned methodology may qualitatively evaluate the vertical cloud structure for the model simulation period. It is envisaged that the present study will open up the possibility of further improvement in the high resolution version of NCUM in the tropics for the Indian summer monsoon associated rainfall events.

  19. Toward the Characterization of Mixed-Phase Clouds Using Remote Sensing

    Science.gov (United States)

    Andronache, C.

    2015-12-01

    Mixed-phase clouds consist of a mixture of ice particles and liquid droplets at temperatures below 0 deg C. They are present in all seasons in many regions of the world, account for about 30% of the global cloud coverage, and are linked to cloud electrification and aircraft icing. The mix of ice particles, liquid droplets, and water vapor is unstable, and such clouds are thought to have a short lifetime. A characteristic parameter is the phase composition of mixed-phase clouds. It affects the cloud life cycle and the rate of precipitation. This parameter is important for cloud parameters retrievals by radar, lidar, and satellite and is relevant for climate modeling. The phase transformation includes the remarkable Wegener-Bergeron-Findeisen (WBF) process. The direction and the rate of the phase transformations depend on the local thermodynamic and microphysical properties. Cloud condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and the dynamic response of clouds to aerosols. The complexity of dynamics and microphysics involved in mixed-phase clouds requires a set of observational and modeling tools that continue to be refined. Among these techniques, the remote sensing methods provide an increasing number of parameters, covering large regions of the world. Thus, a series of studies were dedicated to stratiform mixed-phase clouds revealing longer lifetime than previously thought. Satellite data and aircraft in situ measurements in deep convective clouds suggest that highly supercooled water often occurs in vigorous continental convective storms. In this study, we use cases of convective clouds to discuss the feasibility of mixed-phase clouds characterization and potential advantages of remote sensing.

  20. Influences of Gravity Waves on Convectively Induced Turbulence (CIT): A Review

    Science.gov (United States)

    Sharman, Robert D.; Trier, S. B.

    2018-03-01

    Thunderstorms are known to produce turbulence. Such turbulence is commonly referred to as convectively induced turbulence or CIT, and can be hazardous to aviation. Although this turbulence can occur both within and outside the convection, out-of-cloud CIT is particularly hazardous, since it occurs in clear air and cannot be seen by eye or onboard radar. Furthermore, due to its small scale and its ties to the underlying convection, it is very difficult to forecast. Guidelines for out-of-cloud CIT avoidance are available, but they are oversimplified and can be misleading. In the search for more appropriate and physically based avoidance guidelines, considerable research has been conducted in recent years on the nature of the phenomenon, and in particular, its connection to gravity waves generated by the convection. This paper reviews the advances in our understanding of out-of-cloud CIT and its relation to convective gravity waves, and provides several detailed examples of observed cases to elucidate some of the underlying dynamics.

  1. A review on regional convection permitting climate modeling

    Science.gov (United States)

    van Lipzig, Nicole; Prein, Andreas; Brisson, Erwan; Van Weverberg, Kwinten; Demuzere, Matthias; Saeed, Sajjad; Stengel, Martin

    2016-04-01

    With the increase of computational resources, it has recently become possible to perform climate model integrations where at least part the of convection is resolved. Since convection-permitting models (CPMs) are performing better than models where convection is parameterized, especially for high-impact weather like extreme precipitation, there is currently strong scientific progress in this research domain (Prein et al., 2015). Another advantage of CPMs, that have a horizontal grid spacing climate model COSMO-CLM is frequently applied for CPM simulations, due to its non-hydrostatic dynamics and open international network of scientists. This presentation consists of an overview of the recent progress in CPM, with a focus on COSMO-CLM. It consists of three parts, namely the discussion of i) critical components of CPM, ii) the added value of CPM in the present-day climate and iii) the difference in climate sensitivity in CPM compared to coarser scale models. In terms of added value, the CPMs especially improve the representation of precipitation's, diurnal cycle, intensity and spatial distribution. However, an in depth-evaluation of cloud properties with CCLM over Belgium indicates a strong underestimation of the cloud fraction, causing an overestimation of high temperature extremes (Brisson et al., 2016). In terms of climate sensitivity, the CPMs indicate a stronger increase in flash floods, changes in hail storm characteristics, and reductions in the snowpack over mountains compared to coarser scale models. In conclusion, CPMs are a very promising tool for future climate research. However, additional efforts are necessary to overcome remaining deficiencies, like improving the cloud characteristics. This will be a challenging task due to compensating deficiencies that currently exist in `state-of-the-art' models, yielding a good representation of average climate conditions. In the light of using CPMs to study climate change it is necessary that these deficiencies

  2. Statistics of Deep Convection in the Congo Basin Derived From High-Resolution Simulations.

    Science.gov (United States)

    White, B.; Stier, P.; Kipling, Z.; Gryspeerdt, E.; Taylor, S.

    2016-12-01

    Convection transports moisture, momentum, heat and aerosols through the troposphere, and so the temporal variability of convection is a major driver of global weather and climate. The Congo basin is home to some of the most intense convective activity on the planet and is under strong seasonal influence of biomass burning aerosol. However, deep convection in the Congo basin remains under studied compared to other regions of tropical storm systems, especially when compared to the neighbouring, relatively well-understood West African climate system. We use the WRF model to perform a high-resolution, cloud-system resolving simulation to investigate convective storm systems in the Congo. Our setup pushes the boundaries of current computational resources, using a 1 km grid length over a domain covering millions of square kilometres and for a time period of one month. This allows us to draw statistical conclusions on the nature of the simulated storm systems. Comparing data from satellite observations and the model enables us to quantify the diurnal variability of deep convection in the Congo basin. This approach allows us to evaluate our simulations despite the lack of in-situ observational data. This provides a more comprehensive analysis of the diurnal cycle than has previously been shown. Further, we show that high-resolution convection-permitting simulations performed over near-seasonal timescales can be used in conjunction with satellite observations as an effective tool to evaluate new convection parameterisations.

  3. Lightning Prediction using Electric Field Measurements Associated with Convective Events at a Tropical Location

    Science.gov (United States)

    Jana, S.; Chakraborty, R.; Maitra, A.

    2017-12-01

    Nowcasting of lightning activities during intense convective events using a single electric field monitor (EFM) has been carried out at a tropical location, Kolkata (22.65oN, 88.45oE). Before and at the onset of heavy lightning, certain changes of electric field (EF) can be related to high liquid water content (LWC) and low cloud base height (CBH). The present study discusses the utility of EF observation to show a few aspects of convective events. Large convective cloud showed by high LWC and low CBH can be detected from EF variation which could be a precursor of upcoming convective events. Suitable values of EF gradient can be used as an indicator of impending lightning events. An EF variation of 0.195 kV/m/min can predict lightning within 17.5 km radius with a probability of detection (POD) of 91% and false alarm rate (FAR) of 8% with a lead time of 45 min. The total number of predicted lightning strikes is nearly 9 times less than that measured by the lightning detector. This prediction technique can, therefore, give an estimate of cloud to ground (CG) and intra cloud (IC) lighting occurrences within the surrounding area. This prediction technique involving POD, FAR and lead time information shows a better prediction capability compared to the techniques reported earlier. Thus an EFM can be effectively used for prediction of lightning events at a tropical location.

  4. Surface and atmospheric controls on the onset of moist convection over land

    NARCIS (Netherlands)

    Gentine, P.; Holtslag, A.A.M.; Andrea, D' F.; Ek, M.

    2013-01-01

    The onset of moist convection over land is investigated using a conceptual approach with a slab boundary layer model. We here determine the essential factors for the onset of boundary layer clouds over land, and study their relative importance. They are: 1) the ratio of the temperature to the

  5. Lightning characteristics of derecho producing mesoscale convective systems

    Science.gov (United States)

    Bentley, Mace L.; Franks, John R.; Suranovic, Katelyn R.; Barbachem, Brent; Cannon, Declan; Cooper, Stonie R.

    2016-06-01

    Derechos, or widespread, convectively induced wind storms, are a common warm season phenomenon in the Central and Eastern United States. These damaging and severe weather events are known to sweep quickly across large spatial regions of more than 400 km and produce wind speeds exceeding 121 km h-1. Although extensive research concerning derechos and their parent mesoscale convective systems already exists, there have been few investigations of the spatial and temporal distribution of associated cloud-to-ground lightning with these events. This study analyzes twenty warm season (May through August) derecho events between 2003 and 2013 in an effort to discern their lightning characteristics. Data used in the study included cloud-to-ground flash data derived from the National Lightning Detection Network, WSR-88D imagery from the University Corporation for Atmospheric Research, and damaging wind report data obtained from the Storm Prediction Center. A spatial and temporal analysis was conducted by incorporating these data into a geographic information system to determine the distribution and lightning characteristics of the environments of derecho producing mesoscale convective systems. Primary foci of this research include: (1) finding the approximate size of the lightning activity region for individual and combined event(s); (2) determining the intensity of each event by examining the density and polarity of lightning flashes; (3) locating areas of highest lightning flash density; and (4) to provide a lightning spatial analysis that outlines the temporal and spatial distribution of flash activity for particularly strong derecho producing thunderstorm episodes.

  6. Cloud management and security

    CERN Document Server

    Abbadi, Imad M

    2014-01-01

    Written by an expert with over 15 years' experience in the field, this book establishes the foundations of Cloud computing, building an in-depth and diverse understanding of the technologies behind Cloud computing. In this book, the author begins with an introduction to Cloud computing, presenting fundamental concepts such as analyzing Cloud definitions, Cloud evolution, Cloud services, Cloud deployment types and highlighting the main challenges. Following on from the introduction, the book is divided into three parts: Cloud management, Cloud security, and practical examples. Part one presents the main components constituting the Cloud and federated Cloud infrastructure(e.g., interactions and deployment), discusses management platforms (resources and services), identifies and analyzes the main properties of the Cloud infrastructure, and presents Cloud automated management services: virtual and application resource management services. Part two analyzes the problem of establishing trustworthy Cloud, discuss...

  7. Barrier Effect of the Indo-Pacific Maritime Continent on the MJO

    Science.gov (United States)

    Ling, Jian; Zhang, Chidong

    2017-04-01

    Explanations for the barrier effect of the Indo-Pacific Maritime Continent (MC) on the MJO should satisfy two criteria. First, they should include specific features of the MC, namely, its intricate land-sea distributions and elevated terrains. Second, they should include mechanisms for both the barrier effect and its overcoming by some MJO events. Guided by these two criteria, we applied a precipitation-tracking method to identify MJO events that propagate across the MC (MJO-C) and those that are blocked by the MC (MJO-B). About a half of MJO events that form over the Indian Ocean propagate through the MC. Most of them (> 75%) become weakened over the MC. The barrier effect cannot be explained in terms of the strength, horizontal scale, or spatial distribution of MJO convection when it approaches the MC from the west. A distinction between MJO-B and MJO-C is their precipitation over the sea vs. land in the MC region. MJO-C events rain more over the sea than over land, whereas land rainfall dominates for MJO-B. This suggests that inhibiting convective development over the sea could be a possible mechanism for the barrier effect of the MC. Preceding conditions for MJO-C include stronger low-level zonal moisture flux convergence and higher SST higher in the MC region. Possible connections between these large-scale conditions and the land vs. sea distributions of MJO rainfall through the diurnal cycle are discussed.

  8. 78 FR 14546 - Seagull Maritime Agencies Private Ltd. v. Gren Automotive, Inc., Centrus Automotive Distributors...

    Science.gov (United States)

    2013-03-06

    ... FEDERAL MARITIME COMMISSION [Docket No. 13-03] Seagull Maritime Agencies Private Ltd. v. Gren... Complaint and Assignment Notice is given that a complaint has been filed with the Federal Maritime Commission (Commission) by Seagull Maritime Agencies Private Limited (``SMA''), hereinafter ``Complainant...

  9. 47 CFR 80.469 - Maritime mobile repeater stations in Alaska.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Maritime mobile repeater stations in Alaska. 80... RADIO SERVICES STATIONS IN THE MARITIME SERVICES Public Coast Stations Use of Telephony § 80.469 Maritime mobile repeater stations in Alaska. (a) Maritime mobile repeater stations are authorized to extend...

  10. 32 CFR 536.121 - Claims not payable as maritime claims.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Claims not payable as maritime claims. 536.121... ACCOUNTS CLAIMS AGAINST THE UNITED STATES Maritime Claims § 536.121 Claims not payable as maritime claims... (except at (e) and (k)), and 536.46; (b) Are not maritime in nature; (c) Are not in the best interests of...

  11. 33 CFR 105.230 - Maritime Security (MARSEC) Level coordination and implementation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maritime Security (MARSEC) Level..., DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARITIME SECURITY: FACILITIES Facility Security Requirements § 105.230 Maritime Security (MARSEC) Level coordination and implementation. (a) The facility owner...

  12. 33 CFR 104.240 - Maritime Security (MARSEC) Level coordination and implementation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maritime Security (MARSEC) Level..., DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARITIME SECURITY: VESSELS Vessel Security Requirements § 104.240 Maritime Security (MARSEC) Level coordination and implementation. (a) The vessel owner or...

  13. Jovian meterology: Large-scale moist convection without a lower boundary

    Science.gov (United States)

    Gierasch, P. J.

    1975-01-01

    It is proposed that Jupiter's cloud bands represent large scale convection whose character is determined by the phase change of water at a level where the temperature is about 275K. It is argued that there are three important layers in the atmosphere: a tropopause layer where emission to space occurs; an intermediate layer between the tropopause and the water cloud base; and the deep layer below the water cloud. All arguments are only semi-quantitative. It is pointed out that these ingredients are essential to Jovian meteorology.

  14. Cloud time

    CERN Document Server

    Lockwood, Dean

    2012-01-01

    The ‘Cloud’, hailed as a new digital commons, a utopia of collaborative expression and constant connection, actually constitutes a strategy of vitalist post-hegemonic power, which moves to dominate immanently and intensively, organizing our affective political involvements, instituting new modes of enclosure, and, crucially, colonizing the future through a new temporality of control. The virtual is often claimed as a realm of invention through which capitalism might be cracked, but it is precisely here that power now thrives. Cloud time, in service of security and profit, assumes all is knowable. We bear witness to the collapse of both past and future virtuals into a present dedicated to the exploitation of the spectres of both.

  15. A Numerical Study of Vortex and Precipitating Cloud Merging in Middle Latitudes

    Institute of Scientific and Technical Information of China (English)

    PING Fan; LUO Zhe-Xian; JU Jian-Hua

    2006-01-01

    @@ We mainly focus on the study of precipitating cloud merging associated with vortex merging. The vortex and precipitating cloud merging are simulated by the cloud resolving model from 0000 21 to 1800 23 July 2003. The results show that the model well simulates vortex circulation associated with precipitating clouds. It is also proven that the vortex merging follows the precipitating cloud merging although vortices show the spatial and temporal differences. The convection vorticity vector is introduced to describe the merging processes. Two merging cases are identified during the 42-h simulation and are studied.

  16. Convection in Porous Media

    CERN Document Server

    Nield, Donald A

    2013-01-01

    Convection in Porous Media, 4th Edition, provides a user-friendly introduction to the subject, covering a wide range of topics, such as fibrous insulation, geological strata, and catalytic reactors. The presentation is self-contained, requiring only routine mathematics and the basic elements of fluid mechanics and heat transfer. The book will be of use not only to researchers and practicing engineers as a review and reference, but also to graduate students and others entering the field. The new edition features approximately 1,750 new references and covers current research in nanofluids, cellular porous materials, strong heterogeneity, pulsating flow, and more. Recognized as the standard reference in the field Includes a comprehensive, 250-page reference list Cited over 2300 times to date in its various editions Serves as an introduction for those entering the field and as a comprehensive reference for experienced researchers Features new sections on nanofluids, carbon dioxide sequestration, and applications...

  17. Temperature-Driven Convection

    Science.gov (United States)

    Bohan, Richard J.; Vandegrift, Guy

    2003-02-01

    Warm air aloft is stable. This explains the lack of strong winds in a warm front and how nighttime radiative cooling can lead to motionless air that can trap smog. The stability of stratospheric air can be attributed to the fact that it is heated from above as ultraviolet radiation strikes the ozone layer. On the other hand, fluid heated from below is unstable and can lead to Bernard convection cells. This explains the generally turbulent nature of the troposphere, which receives a significant fraction of its heat directly from the Earth's warmer surface. The instability of cold fluid aloft explains the violent nature of a cold front, as well as the motion of Earth's magma, which is driven by radioactive heating deep within the Earth's mantle. This paper describes how both effects can be demonstrated using four standard beakers, ice, and a bit of food coloring.

  18. Convection in porous media

    CERN Document Server

    Nield, Donald A

    1992-01-01

    This book provides a user-friendly introduction to the topic of convection in porous media The authors as- sume that the reader is familiar with the basic elements of fluid mechanics and heat transfer, but otherwise the book is self-contained The book will be useful both as a review (for reference) and as a tutorial work, suitable as a textbook in a graduate course or seminar The book brings into perspective the voluminous research that has been performed during the last two decades The field has recently exploded because of worldwide concern with issues such as energy self-sufficiency and pollution of the environment Areas of application include the insulation of buildings and equipment, energy storage and recovery, geothermal reservoirs, nuclear waste disposal, chemical reactor engineering, and the storage of heat-generating materials such as grain and coal Geophysical applications range from the flow of groundwater around hot intrusions to the stability of snow against avalanches

  19. Seasonal Scale Convective-Stratiform Pricipitation Variabilities at Tropics

    Science.gov (United States)

    S, Sreekanth T.

    begin{center} Large Seasonal Scale Convective-Stratiform Pricipitation Variabilities at Tropics Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) and V Sasi Kumar (2) *Centre for Earth Science Studies, Akkulam, Thiruvananthapuram (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) 32. NCC Nagar Peroorkada, Thiruvananthapuram ABSTRACT This study investigates the variabilities of convective and stratiform rainfall from 2011 to 2013 at a tropical coastal station in three seasons viz Pre-Monsoon (March-May), Monsoon (June-September) and Post-Monsoon (October-December). Understanding the climatological variability of these two dominant forms of precipitation and their implications in the total rainfall were the main objectives of this investigation. Variabilities in the frequency & duration of events, rain rate & total number of rain drops distribution in different events and the accumulated amount of rain water were analysed. Based on the ground & radar observations from optical & impact disdrometers, Micro Rain Radar and Atmospheric Electric Field Mill, precipitation events were classified into convective and stratiform in three seasons. Classification was done by the method followed by Testud et al (2001) and as an additional information electrical behaviour of clouds from Atmospheric Electric Field Mill is also used. Events which could not be included in both types were termed as 'mixed precipitation' and were included separately. Diurnal variability of the total rainfall in each seasons were also examined. For both convective and stratiform rainfall there exist distinct day-night differences. During nocturnal hours convective rain draged more attention. In all seasons almost 70% of rain duration and 60% of rain events of convective origin were confined to nocturnal hours. But stratiform rain was not affected by diurnal variations greatly because night time occurrences of stratiform duration and events were less than 50%. Also in Monsoon above 35% of

  20. The tropical Atlantic surface wind divergence belt and its effect on clouds

    OpenAIRE

    Y. Tubul; I. Koren; O. Altaratz

    2015-01-01

    A well-defined surface wind divergence (SWD) belt with distinct cloud properties forms over the equatorial Atlantic during the boreal summer months. This belt separates the deep convective clouds of the intertropical convergence zone (ITCZ) from the shallow marine stratocumulus cloud decks forming over the cold-water subtropical region of the southern Hadley cell. Using the QuikSCAT-SeaWinds and Aqua-MODIS instruments, we examined the large-scale spatiotemporal ...

  1. The tropical Atlantic surface wind divergence belt and its effect on clouds

    OpenAIRE

    Y. Tubul; I. Koren; O. Altaratz

    2015-01-01

    A well-defined surface wind divergence (SWD) belt with distinct cloud properties forms over the equatorial Atlantic during the boreal summer months. This belt separates the deep convective clouds of the Intertropical Convergence Zone (ITCZ) from the shallow marine stratocumulus cloud decks forming over the cold-water subtropical region of the southern branch of the Hadley cell in the Atlantic. Using the QuikSCAT-SeaWinds and Aqua-MODIS instruments, we examined the large-scal...

  2. Interrelationship between cloud cover and sensible heat flux over ...

    Indian Academy of Sciences (India)

    Micro-meteorological tower observations of MONTBLEX (Monsoon Trough Boundary Layer Experiment)-1990, combined with routine surface observations at Jodhpur in the dry convective sector of Indian summer monsoon trough are used to examine the interrelationship between total cloud cover (TCC) and surface ...

  3. Impact of cloud microphysics on cloud-radiation interactions in the CSU general circulation model

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, L.D.; Randall, D.A.

    1995-04-01

    Our ability to study and quantify the impact of cloud-radiation interactions in studying global scale climate variations strongly relies upon the ability of general circulation models (GCMs) to simulate the coupling between the spatial and temporal variations of the model-generated cloudiness and atmospheric moisture budget components. In particular, the ability of GCMs to reproduce the geographical distribution of the sources and sinks of the planetary radiation balance depends upon their representation of the formation and dissipation of cloudiness in conjunction with cloud microphysics processes, and the fractional amount and optical characteristics of cloudiness in conjunction with the mass of condensate stored in the atmosphere. A cloud microphysics package which encompasses five prognostic variables for the mass of water vapor, cloud water, cloud ice, rain, and snow has been implemented in the Colorado State University General Circulation Model (CSU GCM) to simulate large-scale condensation processes. Convection interacts with the large-scale environment through the detrainment of cloud water and cloud ice at the top of cumulus towers. The cloud infrared emissivity and cloud optical depth of the model-generated cloudiness are interactive and depend upon the mass of cloud water and cloud ice suspended in the atmosphere. The global atmospheric moisture budget and planetary radiation budget of the CSU GCM obtained from a perpetual January simulation are discussed. Geographical distributions of the atmospheric moisture species are presented. Global maps of the top-of-atmosphere outgoing longwave radiation and planetary albedo are compared against Earth Radiation Budget Experiment (ERBE) satellite data.

  4. Relating large-scale subsidence to convection development in Arctic mixed-phase marine stratocumulus

    Science.gov (United States)

    Young, Gillian; Connolly, Paul J.; Dearden, Christopher; Choularton, Thomas W.

    2018-02-01

    Large-scale subsidence, associated with high-pressure systems, is often imposed in large-eddy simulation (LES) models to maintain the height of boundary layer (BL) clouds. Previous studies have considered the influence of subsidence on warm liquid clouds in subtropical regions; however, the relationship between subsidence and mixed-phase cloud microphysics has not specifically been studied. For the first time, we investigate how widespread subsidence associated with synoptic-scale meteorological features can affect the microphysics of Arctic mixed-phase marine stratocumulus (Sc) clouds. Modelled with LES, four idealised scenarios - a stable Sc, varied droplet (Ndrop) or ice (Nice) number concentrations, and a warming surface (representing motion southwards) - were subjected to different levels of subsidence to investigate the cloud microphysical response. We find strong sensitivities to large-scale subsidence, indicating that high-pressure systems in the ocean-exposed Arctic regions have the potential to generate turbulence and changes in cloud microphysics in any resident BL mixed-phase clouds.Increased cloud convection is modelled with increased subsidence, driven by longwave radiative cooling at cloud top and rain evaporative cooling and latent heating from snow growth below cloud. Subsidence strengthens the BL temperature inversion, thus reducing entrainment and allowing the liquid- and ice-water paths (LWPs, IWPs) to increase. Through increased cloud-top radiative cooling and subsequent convective overturning, precipitation production is enhanced: rain particle number concentrations (Nrain), in-cloud rain mass production rates, and below-cloud evaporation rates increase with increased subsidence.Ice number concentrations (Nice) play an important role, as greater concentrations suppress the liquid phase; therefore, Nice acts to mediate the strength of turbulent overturning promoted by increased subsidence. With a warming surface, a lack of - or low - subsidence

  5. 4M Study to Support Indonesia's Maritime Tourism Development

    Directory of Open Access Journals (Sweden)

    Achmadi Bambang Sulistiyono

    2017-12-01

    Full Text Available Indonesia as an archipelagic state with given abundant natural resources need a sustainable development in many aspects to strengthen its position in international community. Current Government vision in archipelago thinking aims at the development of maritime sector including maritime tourism and connectivity to get better equality regional development. Each region has its special potential assets and needs good concept of development design based on the regional development agenda. Smart, Merchant, and Festive are the types of conceptual design development for passenger terminal, while booster marina and enhancer marina has its role to make the development of maritime tourism locally connected internationally recognized.

  6. THE THREAT OF THE CURRENT MARITIME PIRACY

    Directory of Open Access Journals (Sweden)

    JUAN C. FERNÁNDEZ SANZ

    2017-12-01

    Full Text Available This study aims to conduct an analysis of the current piracy situation -as defined in the UN Convention on the Law of the Sea 1982- and the International Maritime Organization’s armed robbery against ships concept. This analysis is focusing on those places in which it is more common the occurrence of these violations, such as Somalia and Southeast Asia. This study includes a statement of its causal factors, as well as a review of statistical and ‘modus operandi’ of those crimes. It will be also shown the identification of the geographical zones where the attacks at sea are more frequently. Finally it an study of the the answers and the naval operations that the international community has developed against those felonies, will be presented.

  7. Effects of Greenshipping to the Maritime Industry

    Directory of Open Access Journals (Sweden)

    E. A. Ogbonnaya

    2013-04-01

    Full Text Available In order to keep focus on the important agenda of sustainability which has lately become an issue of priority, the maritime industry must implement technologies on existing vessels and on those under construction so as to reduce their emissions into the environment. This study examines three potential sources of emission and also identifies a set of emission control measures that are available and could, if fully applied, reduce emission by 19.058%. With the waste heat recovery system, about 2500 kW of energy are saved, thereby increasing the efficiency to 59.11% having about 10.13% gain compared to engines without a waste heat recovery system. It is therefore recommended that the use of waste heat recovery systems should be encouraged on marine vessels to reduce the impact of noxious gasses into the atmosphere.

  8. Shipment of LLW by intercoastal maritime service

    International Nuclear Information System (INIS)

    Barbour, D.A.

    1985-01-01

    Transportation costs are a significant element of total waste disposal costs. In 1982, Nuclear Metals, Inc. (NMI) began a series of tests and investigations to examine the feasibility of using alternative modes for its low-level waste (LLW) shipments. NMI's investigations and experience have identified significant problems in transporting LLW by rail. Intercoastal maritime service, however, has been demonstrated as a safe and cost-effective way of transporting LLW from eastern seaboard generation sites to the repository at Beatty, Nevada. Intuition is an unreliable guide in this area. Waste managers need to periodically assess and compare combined transportation and burial costs for all site options to ensure that disposal operations are conducted in the most rational way

  9. Maritime Situational Awareness: The MARISS Experience

    Science.gov (United States)

    Margarit, G.; Tabasco, A.; Gomez, C.

    2010-04-01

    This paper presents the operational solution developed by GMV to provide support to maritime situational awareness via Earth Observation (EO) technologies. The concept falls on integrating the information retrieved from Synthetic Aperture Radar (SAR) images and transponder-based polls (AIS and similar) in an advanced GeoPortal web. The service has been designed in the framework of the MARISS project, a project conceived to help improving ship monitoring with the support of a large user segment. In this context, the interaction with official agencies has provided good feedback about system performance and its usefulness in supporting monitoring and surveillance tasks. Some representative samples are analyzed along the paper in order to validate key kernel utilities, such as ship and coastline detection, and ship classification. They justify the promotion of extended R&D activities to increase monitoring performance and to include advanced added- value tools, such as decision making and route tracking.

  10. A Condensation–coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Kazumasa; Okuzumi, Satoshi [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan)

    2017-02-01

    A number of transiting exoplanets have featureless transmission spectra that might suggest the presence of clouds at high altitudes. A realistic cloud model is necessary to understand the atmospheric conditions under which such high-altitude clouds can form. In this study, we present a new cloud model that takes into account the microphysics of both condensation and coalescence. Our model provides the vertical profiles of the size and density of cloud and rain particles in an updraft for a given set of physical parameters, including the updraft velocity and the number density of cloud condensation nuclei (CCNs). We test our model by comparing with observations of trade-wind cumuli on Earth and ammonia ice clouds in Jupiter. For trade-wind cumuli, the model including both condensation and coalescence gives predictions that are consistent with observations, while the model including only condensation overestimates the mass density of cloud droplets by up to an order of magnitude. For Jovian ammonia clouds, the condensation–coalescence model simultaneously reproduces the effective particle radius, cloud optical thickness, and cloud geometric thickness inferred from Voyager observations if the updraft velocity and CCN number density are taken to be consistent with the results of moist convection simulations and Galileo probe measurements, respectively. These results suggest that the coalescence of condensate particles is important not only in terrestrial water clouds but also in Jovian ice clouds. Our model will be useful to understand how the dynamics, compositions, and nucleation processes in exoplanetary atmospheres affect the vertical extent and optical thickness of exoplanetary clouds via cloud microphysics.

  11. A Condensation–coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds

    International Nuclear Information System (INIS)

    Ohno, Kazumasa; Okuzumi, Satoshi

    2017-01-01

    A number of transiting exoplanets have featureless transmission spectra that might suggest the presence of clouds at high altitudes. A realistic cloud model is necessary to understand the atmospheric conditions under which such high-altitude clouds can form. In this study, we present a new cloud model that takes into account the microphysics of both condensation and coalescence. Our model provides the vertical profiles of the size and density of cloud and rain particles in an updraft for a given set of physical parameters, including the updraft velocity and the number density of cloud condensation nuclei (CCNs). We test our model by comparing with observations of trade-wind cumuli on Earth and ammonia ice clouds in Jupiter. For trade-wind cumuli, the model including both condensation and coalescence gives predictions that are consistent with observations, while the model including only condensation overestimates the mass density of cloud droplets by up to an order of magnitude. For Jovian ammonia clouds, the condensation–coalescence model simultaneously reproduces the effective particle radius, cloud optical thickness, and cloud geometric thickness inferred from Voyager observations if the updraft velocity and CCN number density are taken to be consistent with the results of moist convection simulations and Galileo probe measurements, respectively. These results suggest that the coalescence of condensate particles is important not only in terrestrial water clouds but also in Jovian ice clouds. Our model will be useful to understand how the dynamics, compositions, and nucleation processes in exoplanetary atmospheres affect the vertical extent and optical thickness of exoplanetary clouds via cloud microphysics.

  12. High-Resolution Global Modeling of the Effects of Subgrid-Scale Clouds and Turbulence on Precipitating Cloud Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bogenschutz, Peter [National Center for Atmospheric Research, Boulder, CO (United States); Moeng, Chin-Hoh [National Center for Atmospheric Research, Boulder, CO (United States)

    2015-10-13

    The PI’s at the National Center for Atmospheric Research (NCAR), Chin-Hoh Moeng and Peter Bogenschutz, have primarily focused their time on the implementation of the Simplified-Higher Order Turbulence Closure (SHOC; Bogenschutz and Krueger 2013) to the Multi-scale Modeling Framework (MMF) global model and testing of SHOC on deep convective cloud regimes.

  13. Stellar convection and dynamo theory

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, R L

    1989-10-01

    In considering the large scale stellar convection problem the outer layers of a star are modelled as two co-rotating plane layers coupled at a fluid/fluid interface. Heating from below causes only the upper fluid to convect, although this convection can penetrate into the lower fluid. Stability analysis is then used to find the most unstable mode of convection. With parameters appropriate to the Sun the most unstable mode is steady convection in thin cells (aspect ratio {approx equal} 0.2) filling the convection zone. There is negligible vertical motion in the lower fluid, but considerable thermal penetration, and a large jump in helicity at the interface, which has implications for dynamo theory. An {alpha}{omega} dynamo is investigated in isolation from the convection problem. Complexity is included by allowing both latitudinal and time dependence in the magnetic fields. The nonlinear dynamics of the resulting partial differential equations are analysed in considerable detail. On varying the main control parameter D (the dynamo number), many transitions of behaviour are found involving many forms of time dependence, but not chaos. Further, solutions which break equatorial symmetry are common and provide a theoretical explanation of solar observations which have this symmetry. Overall the behaviour was more complicated than expected. In particular, there were multiple stable solutions at fixed D, meaning that similar stars can have very different magnetic patterns, depending upon their history. (author).

  14. Essentials of cloud computing

    CERN Document Server

    Chandrasekaran, K

    2014-01-01

    ForewordPrefaceComputing ParadigmsLearning ObjectivesPreambleHigh-Performance ComputingParallel ComputingDistributed ComputingCluster ComputingGrid ComputingCloud ComputingBiocomputingMobile ComputingQuantum ComputingOptical ComputingNanocomputingNetwork ComputingSummaryReview PointsReview QuestionsFurther ReadingCloud Computing FundamentalsLearning ObjectivesPreambleMotivation for Cloud ComputingThe Need for Cloud ComputingDefining Cloud ComputingNIST Definition of Cloud ComputingCloud Computing Is a ServiceCloud Computing Is a Platform5-4-3 Principles of Cloud computingFive Essential Charact

  15. Convectively-driven cold layer and its influences on moisture in the UTLS

    Science.gov (United States)

    Kim, J.; Randel, W. J.; Birner, T.

    2016-12-01

    Characteristics of the cold anomaly in the tropical tropopause layer (TTL) that is commonly observed with deep convection are examined using CloudSat and Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS radio occultation measurements. Deep convection is sampled based on the cloud top height (>17 km) from CloudSat 2B-CLDCLASS, and then temperature profiles from COSMIC are composited around the deep convection. The composite temperature shows anomalously warm troposphere (up to 14 km) and a significantly cold layer near the tropopause (at 16-18 km) in the regions of deep convection. Generally in the tropics, the cold layer has very large horizontal scale (2,000 - 6,000 km) compared to that of mesoscale convective cluster, and it lasts one or two weeks with minimum temperature anomaly of - 2K. The cold layer shows slight but clear eastward-tilted vertical structure in the deep tropics indicating a large-scale Kelvin wave response. Further analyses on circulation patterns suggest that the anomaly can be explained as a part of Gill-type response in the TTL to deep convective heating in the troposphere. Response of moisture to the cold layer is also examined in the upper troposphere and lower stratosphere using microwave limb sounder (MLS) measurements. The water vapor anomalies show coherent structures with the temperature and circulation anomalies. A clear dry anomaly is found in the cold layer and its outflow region, implying a large-scale dehydration process due to the convectively driven cold layer in the upper TTL.

  16. Convectively Driven Tropopause-Level Cooling and Its Influences on Stratospheric Moisture

    Science.gov (United States)

    Kim, Joowan; Randel, William J.; Birner, Thomas

    2018-01-01

    Characteristics of the tropopause-level cooling associated with tropical deep convection are examined using CloudSat radar and Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS radio occultation measurements. Extreme deep convection is sampled based on the cloud top height (>17 km) from CloudSat, and colocated temperature profiles from COSMIC are composited around the deep convection. Response of moisture to the tropopause-level cooling is also examined in the upper troposphere and lower stratosphere using microwave limb sounder measurements. The composite temperature shows an anomalous warming in the troposphere and a significant cooling near the tropopause (at 16-19 km) when deep convection occurs over the western Pacific, particularly during periods with active Madden-Julian Oscillation (MJO). The composite of the tropopause cooling has a large horizontal scale ( 6,000 km in longitude) with minimum temperature anomaly of -2 K, and it lasts more than 2 weeks with support of mesoscale convective clusters embedded within the envelope of the MJO. The water vapor anomalies show strong correlation with the temperature anomalies (i.e., dry anomaly in the cold anomaly), showing that the convectively driven tropopause cooling actively dehydrate the lower stratosphere in the western Pacific region. The moisture is also affected by anomalous Matsuno-Gill-type circulation associated with the cold anomaly, in which dry air spreads over a wide range in the tropical tropopause layer (TTL). These results suggest that convectively driven tropopause cooling and associated transient circulation play an important role in the large-scale dehydration process in the TTL.

  17. Using ISCCP Weather States to Decompose Cloud Radiative Effects

    Science.gov (United States)

    Oreopoulos, L.; Rossow, W. B.

    2012-01-01

    The presentation will examine the shortwave (SW) and longwave (LW) cloud radiative effect CRE (aka "cloud radiative forcing") at the top-of-the-atmosphere and surface of ISCCP weather states (aka "cloud regimes") in three distinct geographical zones, one tropical and two mid-latitude. Our goal is to understand and quantify the contribution of the different cloud regimes to the planetary radiation budget. In the tropics we find that the three most convectively active states are the ones with largest SW, LW and net TOA CRE contributions to the overall daytime tropical CRE budget. They account for 59%, 71% and 55% of the total CRE, respectively. The boundary layer-dominated weather states account for only 34% of the total SW CRE and 41% of the total net CRE, so to focus only on them in cloud feedback studies may be imprudent. We also find that in both the northern and southern midlatitude zones only two weather states, the first and third most convectively active with large amounts of nimbostratus-type clouds, contribute ",40% to both the SW and net TOA CRE budgets, highlighting the fact that cloud regimes associated with frontal systems are not only important for weather (precipitation) but also for climate (radiation budget). While all cloud regimes in all geographical zones have a slightly larger SFC than TOA SW CRE, implying cooling of the surface and slight warming of the atmosphere, their LW radiative effects are more subtle: in the tropics the weather states with plentiful high clouds warm the atmosphere while those with copious amounts of low clouds cool the atmosphere. In both midlatitude zones only the weather states with peak cloud fractions at levels above 440 mbar warm the atmosphere while all the rest cool it. These results make the connection of the contrasting CRE effects to the atmospheric dynamics more explicit - "storms" tend to warm the atmosphere whereas fair weather clouds cool it, suggesting a positive feedback of clouds on weather systems. The

  18. Influence of Ice-phase of Hydrometeors on Moist-Convection

    Science.gov (United States)

    Sud, Y. C.; Walker, G. K.

    2003-01-01

    Climate models often ignore the influence of ice-phase physics (IPP) of hydrometeors as a second order effect. This has also been true for McRAS (Microphysics of clouds with Relaxed Arakawa Schubert Scheme) developed by the authors. Recognizing that the temperature sounding is critical for moist-convection, and, that IPP would modify it, we investigated the influence of introducing IPP into McRAS coupled to FvGCM (finite volume General Circulation Model with NCAR physics). We analyzed three 3-yr long simulations; the first called Control Case, CC and had no IPP; the other two called Experiments El and E2 had IPP introduced with two different in-cloud freezing assumptions. Simulation El assumed that all hydrometeors remain liquid in the updraft and freeze upon detrainment. Simulation E2 invoked the in-cloud freezing of new condensate generated at subfreezing temperatures in the updraft while old cloud water continued to ascend as liquid. Upon detrainment, this cloud water also froze like in E1. With these assumptions, about 50% of hydrometeors froze in the tower and the rest froze in the anvil. However, in both El and E2, the frozen hydrometeors melted during fall at the first encounter of above freezing ambient temperature. Comparative analysis revealed that El simulated far more mid-level and far less deep clouds while E2 had modified deep and more mid-level clouds as compared to CC along with some major changes around the melt-level. We infer that IPP produced a more realistic response in E2. At the basic level, the results show that ice-phase processes influence convective detrainment at mid- and deep levels in accord with TOGAGOARE observations. The results suggest that IPP can help to mitigate less-than-observed mid-level and over-abundance of deep convective clouds in McRAS.

  19. The convection patterns in microemulsions

    International Nuclear Information System (INIS)

    Korneta, W.; Lopez Quintela, M.A.; Fernandez Novoa, A.

    1991-07-01

    The Rayleigh-Benard convection in the microemulsion consisting of water (7.5%), cyclohexan (oil-61.7%) and diethylenglycolmonobutylether (surfactant-30.8%) is studied from the onset of convection to the phase separation. The five classes of convection patterns are observed and recorded on the video: localized travelling waves, travelling waves, travelling waves and localized steady rolls, steady rolls and steady polygons. The Fourier transforms and histograms of these patterns are presented. The origin of any pattern is discussed. The intermittent behaviour close to the phase separation was observed. Possible applications of the obtained results are suggested. (author). 6 refs, 4 figs

  20. 17 Years of Cloud Heights from Terra, and Beyond

    Science.gov (United States)

    Davies, R.

    2017-12-01

    The effective cloud height, H, is the integral of observed cloud-top heights, weighted by their frequency of occurrence. Here we look at changes in the effective cloud height, H', as measured by the Multiangle Imaging Spectroradiometer (MISR) on the first Earth Observing System platform, Terra. Terra was launched in December 1999, and now has over 17 years of consistently measured climate records. Globally, HG' has an important influence on Earth's climate, whereas regionally, HR' is a useful measure of low frequency changes in circulation patterns. MISR has a sampling error in the annual mean HG' of ≈11 m, allowing fairly small interannual variations to be detected. This paper extends the previous 15-year summary that showed significant differences in the long term mean hemispheric cloud height changes. Also of interest are the correlations in tropical cloud height changes and related teleconnections. The largest ephemeral values in the annual HR' [over 1.5 km] are noted over the Central Pacific and the Maritime Continent. These changes are strongly anticorrelated with each other, being directly related to changes in ENSO. They are also correlated with the largest ephemeral changes in HG'. Around the equator, we find at least four distinct centres of similar fluctuations in cloud height. This paper examines the relative time dependence of these regional height changes, separately for La Niña and El Niño events, and stresses the value of extending the time series of uniformly measured cloud heights from space beyond EOS-Terra.