The Experts below are selected from a list of 5202 Experts worldwide ranked by ideXlab platform
A De Miguel - One of the best experts on this subject based on the ideXlab platform.
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global diffuse beam and ultraviolet solar irradiance recorded in malta and Atmospheric Component influences under cloudless skies
Solar Energy, 2015Co-Authors: J Bilbao, Roberto Roman, Charles Yousif, Ana Perezburgos, D Mateos, A De MiguelAbstract:Abstract Global ( G ) and diffuse ( G d ) shortwave and global erythemal (UVER) horizontal irradiances and Atmospheric Components like, total ozone column, water vapour column, aerosol optical depth were measured in Malta, at the Institute for Sustainable Energy in the south-eastern village of Marsaxlokk, in the middle of Mediterranean Sea. The effect of solar zenith angle on these irradiances is studied using the measurements and simulations developed with a radiative transfer model. Horizontal global and beam ( G b ) irradiances show a linear relation with zenith solar angle cosine. The role of ozone, scattering by gases, and aerosols is analysed. Simulation model results show that total ozone column, aerosol optical depth and Rayleigh scattering are the main drivers responsible for the behaviour of UVER variations with solar zenith angle (SZA). In the case of global and diffuse shortwave irradiance, the effect of aerosols is the principal determinant.
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global diffuse direct and ultraviolet solar irradiance recorded in malta and Atmospheric Component influences
Energy Procedia, 2014Co-Authors: J Bilbao, Roberto Roman, Charles Yousif, Ana Perezburgos, A De MiguelAbstract:Abstract Global and diffuse shortwave (SW) and global erythemal (UVER) irradiances were measured in Malta, in the middle of Mediterranean Sea. The effect of solar zenith angle on these irradiances is studied using the measurements and simulations developed with a radiative transfer model. The role of ozone, scattering by gases, and aerosols is analyzed. Results show that ozone and Rayleigh scattering are the main drivers responsible for the behavior of UVER variations with SZA. In the case of global and diffuse irradiance, the role of aerosols is the principal determinant.
Alejandro Di Luca - One of the best experts on this subject based on the ideXlab platform.
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the Atmospheric Component of the mediterranean sea water budget in a wrf multi physics ensemble and observations
Climate Dynamics, 2014Co-Authors: Alejandro Di Luca, Emmanouil Flaounas, Philippe Drobinski, Cindy Lebeaupin BrossierAbstract:The use of high resolution atmosphere–ocean coupled regional climate models to study possible future climate changes in the Mediterranean Sea requires an accurate simulation of the Atmospheric Component of the water budget (i.e., evaporation, precipitation and runoff). A specific configuration of the version 3.1 of the weather research and forecasting (WRF) regional climate model was shown to systematically overestimate the Mediterranean Sea water budget mainly due to an excess of evaporation (~1,450 mm yr−1) compared with observed estimations (~1,150 mm yr−1). In this article, a 70-member multi-physics ensemble is used to try to understand the relative importance of various sub-grid scale processes in the Mediterranean Sea water budget and to evaluate its representation by comparing simulated results with observed-based estimates. The physics ensemble was constructed by performing 70 1-year long simulations using version 3.3 of the WRF model by combining six cumulus, four surface/planetary boundary layer and three radiation schemes. Results show that evaporation variability across the multi-physics ensemble (∼10 % of the mean evaporation) is dominated by the choice of the surface layer scheme that explains more than ∼70 % of the total variance and that the overestimation of evaporation in WRF simulations is generally related with an overestimation of surface exchange coefficients due to too large values of the surface roughness parameter and/or the simulation of too unstable surface conditions. Although the influence of radiation schemes on evaporation variability is small (∼13 % of the total variance), radiation schemes strongly influence exchange coefficients and vertical humidity gradients near the surface due to modifications of temperature lapse rates. The precipitation variability across the physics ensemble (∼35 % of the mean precipitation) is dominated by the choice of both cumulus (∼55 % of the total variance) and planetary boundary layer (∼32 % of the total variance) schemes with a strong regional dependence. Most members of the ensemble underestimate total precipitation amounts with biases as large as 250 mm yr−1 over the whole Mediterranean Sea compared with ERA Interim reanalysis mainly due to an underestimation of the number of wet days. The larger number of dry days in simulations is associated with a deficit in the activation of cumulus schemes. Both radiation and planetary boundary layer schemes influence precipitation through modifications on the available water vapor in the boundary layer generally tied with changes in evaporation.
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The Atmospheric Component of the Mediterranean Sea water budget in a WRF multi-physics ensemble and observations
Climate Dynamics, 2014Co-Authors: Alejandro Di Luca, Emmanouil Flaounas, Philippe Drobinski, Cindy Lebeaupin BrossierAbstract:International audienceThe use of high resolution atmosphere-ocean coupled regional climate models to study possible future climate changes in the Mediterranean Sea requires an accurate simulation of the Atmospheric Component of the water budget (i.e., evaporation, precipitation and runoff). A specific configuration of the version 3.1 of the weather research and forecasting (WRF) regional climate model was shown to systematically overestimate the Mediterranean Sea water budget mainly due to an excess of evaporation (~1,450 mm yr-1) compared with observed estimations (~1,150 mm yr-1). In this article, a 70-member multi-physics ensemble is used to try to understand the relative importance of various sub-grid scale processes in the Mediterranean Sea water budget and to evaluate its representation by comparing simulated results with observed-based estimates. The physics ensemble was constructed by performing 70 1-year long simulations using version 3.3 of the WRF model by combining six cumulus, four surface/planetary boundary layer and three radiation schemes. Results show that evaporation variability across the multi-physics ensemble (~10 % of the mean evaporation) is dominated by the choice of the surface layer scheme that explains more than ~70 % of the total variance and that the overestimation of evaporation in WRF simulations is generally related with an overestimation of surface exchange coefficients due to too large values of the surface roughness parameter and/or the simulation of too unstable surface conditions. Although the influence of radiation schemes on evaporation variability is small (~13 % of the total variance), radiation schemes strongly influence exchange coefficients and vertical humidity gradients near the surface due to modifications of temperature lapse rates. The precipitation variability across the physics ensemble (~35 % of the mean precipitation) is dominated by the choice of both cumulus (~55 % of the total variance) and planetary boundary layer (~32 % of the total variance) schemes with a strong regional dependence. Most members of the ensemble underestimate total precipitation amounts with biases as large as 250 mm yr-1 over the whole Mediterranean Sea compared with ERA Interim reanalysis mainly due to an underestimation of the number of wet days. The larger number of dry days in simulations is associated with a deficit in the activation of cumulus schemes. Both radiation and planetary boundary layer schemes influence precipitation through modifications on the available water vapor in the boundary layer generally tied with changes in evaporation. © 2014 Springer-Verlag Berlin Heidelberg
Cindy Lebeaupin Brossier - One of the best experts on this subject based on the ideXlab platform.
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the Atmospheric Component of the mediterranean sea water budget in a wrf multi physics ensemble and observations
Climate Dynamics, 2014Co-Authors: Alejandro Di Luca, Emmanouil Flaounas, Philippe Drobinski, Cindy Lebeaupin BrossierAbstract:The use of high resolution atmosphere–ocean coupled regional climate models to study possible future climate changes in the Mediterranean Sea requires an accurate simulation of the Atmospheric Component of the water budget (i.e., evaporation, precipitation and runoff). A specific configuration of the version 3.1 of the weather research and forecasting (WRF) regional climate model was shown to systematically overestimate the Mediterranean Sea water budget mainly due to an excess of evaporation (~1,450 mm yr−1) compared with observed estimations (~1,150 mm yr−1). In this article, a 70-member multi-physics ensemble is used to try to understand the relative importance of various sub-grid scale processes in the Mediterranean Sea water budget and to evaluate its representation by comparing simulated results with observed-based estimates. The physics ensemble was constructed by performing 70 1-year long simulations using version 3.3 of the WRF model by combining six cumulus, four surface/planetary boundary layer and three radiation schemes. Results show that evaporation variability across the multi-physics ensemble (∼10 % of the mean evaporation) is dominated by the choice of the surface layer scheme that explains more than ∼70 % of the total variance and that the overestimation of evaporation in WRF simulations is generally related with an overestimation of surface exchange coefficients due to too large values of the surface roughness parameter and/or the simulation of too unstable surface conditions. Although the influence of radiation schemes on evaporation variability is small (∼13 % of the total variance), radiation schemes strongly influence exchange coefficients and vertical humidity gradients near the surface due to modifications of temperature lapse rates. The precipitation variability across the physics ensemble (∼35 % of the mean precipitation) is dominated by the choice of both cumulus (∼55 % of the total variance) and planetary boundary layer (∼32 % of the total variance) schemes with a strong regional dependence. Most members of the ensemble underestimate total precipitation amounts with biases as large as 250 mm yr−1 over the whole Mediterranean Sea compared with ERA Interim reanalysis mainly due to an underestimation of the number of wet days. The larger number of dry days in simulations is associated with a deficit in the activation of cumulus schemes. Both radiation and planetary boundary layer schemes influence precipitation through modifications on the available water vapor in the boundary layer generally tied with changes in evaporation.
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The Atmospheric Component of the Mediterranean Sea water budget in a WRF multi-physics ensemble and observations
Climate Dynamics, 2014Co-Authors: Alejandro Di Luca, Emmanouil Flaounas, Philippe Drobinski, Cindy Lebeaupin BrossierAbstract:International audienceThe use of high resolution atmosphere-ocean coupled regional climate models to study possible future climate changes in the Mediterranean Sea requires an accurate simulation of the Atmospheric Component of the water budget (i.e., evaporation, precipitation and runoff). A specific configuration of the version 3.1 of the weather research and forecasting (WRF) regional climate model was shown to systematically overestimate the Mediterranean Sea water budget mainly due to an excess of evaporation (~1,450 mm yr-1) compared with observed estimations (~1,150 mm yr-1). In this article, a 70-member multi-physics ensemble is used to try to understand the relative importance of various sub-grid scale processes in the Mediterranean Sea water budget and to evaluate its representation by comparing simulated results with observed-based estimates. The physics ensemble was constructed by performing 70 1-year long simulations using version 3.3 of the WRF model by combining six cumulus, four surface/planetary boundary layer and three radiation schemes. Results show that evaporation variability across the multi-physics ensemble (~10 % of the mean evaporation) is dominated by the choice of the surface layer scheme that explains more than ~70 % of the total variance and that the overestimation of evaporation in WRF simulations is generally related with an overestimation of surface exchange coefficients due to too large values of the surface roughness parameter and/or the simulation of too unstable surface conditions. Although the influence of radiation schemes on evaporation variability is small (~13 % of the total variance), radiation schemes strongly influence exchange coefficients and vertical humidity gradients near the surface due to modifications of temperature lapse rates. The precipitation variability across the physics ensemble (~35 % of the mean precipitation) is dominated by the choice of both cumulus (~55 % of the total variance) and planetary boundary layer (~32 % of the total variance) schemes with a strong regional dependence. Most members of the ensemble underestimate total precipitation amounts with biases as large as 250 mm yr-1 over the whole Mediterranean Sea compared with ERA Interim reanalysis mainly due to an underestimation of the number of wet days. The larger number of dry days in simulations is associated with a deficit in the activation of cumulus schemes. Both radiation and planetary boundary layer schemes influence precipitation through modifications on the available water vapor in the boundary layer generally tied with changes in evaporation. © 2014 Springer-Verlag Berlin Heidelberg
J Bilbao - One of the best experts on this subject based on the ideXlab platform.
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global diffuse beam and ultraviolet solar irradiance recorded in malta and Atmospheric Component influences under cloudless skies
Solar Energy, 2015Co-Authors: J Bilbao, Roberto Roman, Charles Yousif, Ana Perezburgos, D Mateos, A De MiguelAbstract:Abstract Global ( G ) and diffuse ( G d ) shortwave and global erythemal (UVER) horizontal irradiances and Atmospheric Components like, total ozone column, water vapour column, aerosol optical depth were measured in Malta, at the Institute for Sustainable Energy in the south-eastern village of Marsaxlokk, in the middle of Mediterranean Sea. The effect of solar zenith angle on these irradiances is studied using the measurements and simulations developed with a radiative transfer model. Horizontal global and beam ( G b ) irradiances show a linear relation with zenith solar angle cosine. The role of ozone, scattering by gases, and aerosols is analysed. Simulation model results show that total ozone column, aerosol optical depth and Rayleigh scattering are the main drivers responsible for the behaviour of UVER variations with solar zenith angle (SZA). In the case of global and diffuse shortwave irradiance, the effect of aerosols is the principal determinant.
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global diffuse direct and ultraviolet solar irradiance recorded in malta and Atmospheric Component influences
Energy Procedia, 2014Co-Authors: J Bilbao, Roberto Roman, Charles Yousif, Ana Perezburgos, A De MiguelAbstract:Abstract Global and diffuse shortwave (SW) and global erythemal (UVER) irradiances were measured in Malta, in the middle of Mediterranean Sea. The effect of solar zenith angle on these irradiances is studied using the measurements and simulations developed with a radiative transfer model. The role of ozone, scattering by gases, and aerosols is analyzed. Results show that ozone and Rayleigh scattering are the main drivers responsible for the behavior of UVER variations with SZA. In the case of global and diffuse irradiance, the role of aerosols is the principal determinant.
Arun Kumar - One of the best experts on this subject based on the ideXlab platform.
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influence of changes in observations on precipitation a case study for the climate forecast system reanalysis cfsr
Journal of Geophysical Research, 2012Co-Authors: Li Zhang, Arun Kumar, Wanqiu WangAbstract:[1] Reanalysis products often show discontinuities in the time evolution of analyzed fields, particularly for the derived variables, for example, precipitation. In the recently completed Climate Forecast System Reanalysis (CFSR) at the National Centers for Environmental Prediction, a sharp increase in the global mean precipitation around 1998 has been noted. A similar abrupt change also appears in several other reanalyses that have been recently completed. This sharp increase coincides with the introduction of the Advanced TIROS Operational Vertical Sounder (ATOVS) data into the assimilation system. Based on model simulations to complement the CFSR, this study analyzes the reason behind the sudden jump in precipitation. The outputs from both the CFSR and a simulation with the CFSR's Atmospheric Component model forced with the observed sea surface temperature and carbon dioxide concentration are used to understand the precipitation abrupt change in the CFSR. The analysis indicates that the change results from (1) the tendency of the forecast (during the assimilation cycle) to drift toward its mean state that is cooler and drier, (2) the tendency of the assimilation to correct the first guess forecast to a wetter analysis, (3) an analysis that the period after 1998 is in an even wetter mean state due to the ingestion of the ATOVS data, and (4) the combination of previous three factors resulting in a abrupt change in precipitation during the assimilation around 1998. The results presented here may also provide the developers of the reanalysis systems further insights about the possible causes for the change in precipitation around 1998.
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prediction of monthly mean temperature the roles of Atmospheric and land initial conditions and sea surface temperature
Journal of Climate, 2010Co-Authors: Mingyue Chen, Wanqiu Wang, Arun KumarAbstract:Abstract Using the retrospective forecasts from the National Centers for Environmental Prediction (NCEP) coupled atmosphere–ocean Climate Forecast System (CFS) and the Atmospheric Model Intercomparison Project (AMIP) simulations from its uncoupled Atmospheric Component, the NCEP Global Forecast System (GFS), the relative roles of Atmospheric and land initial conditions and the lower boundary condition of sea surface temperatures (SSTs) for the prediction of monthly-mean temperature are investigated. The analysis focuses on the lead-time dependence of monthly-mean prediction skill and its asymptotic value for longer lead times, which could be attributed the Atmospheric response to the slowly varying SST. The results show that the observed Atmospheric and land initial conditions improve the skill of monthly-mean prediction in the extratropics but have little influence in the tropics. However, the influence of initial Atmospheric and land conditions in the extratropics decays rapidly. For 30-day-lead predict...
