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Brian J Soden - One of the best experts on this subject based on the ideXlab platform.

  • diurnal cycle of Convection Clouds and water vapor in the tropical upper troposphere satellites versus a general circulation model
    Journal of Geophysical Research, 2004
    Co-Authors: Baijun Tian, Brian J Soden
    Abstract:

    [1] Global high-resolution (3-hourly, 0.1° × 0.1° longitude-latitude) water vapor (6.7 μm) and window (11 μm) radiances from multiple geostationary satellites are used to document the diurnal cycle of upper tropospheric relative humidity (UTH) and its relationship to deep Convection and high Clouds in the whole tropics and to evaluate the ability of the new Geophysical Fluid Dynamics Laboratory (GFDL) global atmosphere and land model (AM2/LM2) to simulate these diurnal variations. Similar to the diurnal cycle of deep Convection and high Clouds, coherent diurnal variations in UTH are also observed over the deep convective regions, where the daily mean UTH is high. In addition, the diurnal cycle in UTH also features a land-sea contrast: stronger over land but weaker over ocean. UTH tends to peak around midnight over ocean in contrast to 0300 LST over land. Furthermore, UTH is observed to lag high cloud cover by ∼6 hours, and the latter further lags deep Convection, implying that deep Convection serves to moisten the upper troposphere through the evaporation of the cirrus anvil Clouds generated by deep Convection. Compared to the satellite observations, AM2/LM2 can roughly capture the diurnal phases of deep Convection, high cloud cover, and UTH over land; however, the magnitudes are noticeably weaker in the model. Over the oceans the AM2/LM2 has difficulty in simulating both the diurnal phase and amplitude of these quantities. These results reveal some important deficiencies in the model's Convection and cloud parameterization schemes and suggest the lack of a diurnal cycle in SST may be a shortcoming in the boundary forcing for atmospheric models.

  • the diurnal cycle of Convection Clouds and water vapor in the tropical upper troposphere
    Geophysical Research Letters, 2000
    Co-Authors: Brian J Soden
    Abstract:

    Hourly observations of the 6.7 µm water vapor radiances from geostationary satellites are used to document the diurnal cycle in upper tropospheric water vapor and its relationship to cloud cover and Convection. A coherent diurnal cycle in tropical water vapor is observed which lags the variations in cloud cover by approximately 2 hours. The variations in upper tropospheric cloud and water vapor occur (roughly) in phase with changes in deep Convection over land, but nearly 12 hours out of phase with those over ocean. This feature is shown to be associated with differences in the vertical structure of land and ocean Convection and offers a useful test of convective parameterizations in atmospheric models.

Jean-louis Dufresne - One of the best experts on this subject based on the ideXlab platform.

  • improved near surface continental climate in ipsl cm6a lr by combined evolutions of atmospheric and land surface physics
    Journal of Advances in Modeling Earth Systems, 2020
    Co-Authors: Frédérique Cheruy, Agnès Ducharne, Frédéric Hourdin, Ionela Musat, Étienne Vignon, Guillaume Gastineau, Vladislav Bastrikov, Nicolas Vuichard, Binta Diallo, Jean-louis Dufresne
    Abstract:

    This work is motivated by the identification of the land-atmosphere interactions as one of the key sources of uncertainty in climate change simulations. It documents new developments in related processes, namely, boundary layer/Convection/Clouds parameterizations and land surface parameterization in the Earth System Model of the Institut Pierre Simon Laplace (IPSL). Simulations forced by prescribed oceanic conditions are produced with different combinations of atmospheric and land surface parameterizations. They are used to explore the sensitivity to the atmospheric physics and/or soil physics of • major biases in the near surface variables over continents, • the energy and moisture coupling established at the soil/atmosphere interface in not too wet (energy limited) and not too dry (moisture limited) soil moisture regions also known as transition or "hot-spot" regions, • the river runoff at the outlet of major rivers. The package implemented in the IPSL-Climate Model for the Phase 6 of the Coupled Models Intercomparison Project (CMIP6) allows us to reduce several biases in the surface albedo, the snow cover, and the continental surface air temperature in summer as well as in the temperature profile in the surface layer of the polar regions. The interactions between soil moisture and atmosphere in hotspot regions are in better agreement with the observations. Rainfall is also significantly improved in volume and seasonality in several major river basins leading to an overall improvement in river discharge. However, the lack of consideration of floodplains and human influences in the model, for example, dams and irrigation, impacts the realism of simulated discharge. Plain Language Summary Land surface-atmosphere interactions play an essential role in the climate system. They strongly modulate the regional climates and have impacts on the global scale for instance through freshwater release into the oceans. Climate hazards (heat waves, droughts) and their impacts on populations also strongly depend on interactions between land and atmosphere and on their evolution with climate change. Climate models are precious tools to investigate how the Earth climate behaves. The sixth phase of the Climate Model Intercomparison Project (CMIP6) provides important tools to measure the progress and address the remaining open questions regarding the continental climate modeling. The representation of the land-atmosphere coupled system by the IPSL-Climate Model involved in CMIP6 is thoroughly evaluated against observations and compared with simulations using the CMIP5 version. Several biases concerning the temperature over land and over the ice sheets and with the snow cover are significantly reduced. Numerous improvements were made developping advanced parameterizations and tuning of the radiation and of the turbulent mixing in the atmospheric model. The realism of the seasonal

Jarno Mielikainen - One of the best experts on this subject based on the ideXlab platform.

  • optimizing total energy mass flux temf planetary boundary layer scheme for intel s many integrated core mic architecture
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2015
    Co-Authors: Jarno Mielikainen, Bormin Huang, Hunglung Allen Huang
    Abstract:

    In order to make use of the ever-improving microprocessor performance, the applications must be modified to take advantage of the parallelism of today’s microprocessors. One such application that needs to be modernized is the weather research and forecasting (WRF) model, which is designed for numerical weather prediction and atmospheric research. The WRF software infrastructure consists of several components such as dynamic solvers and physics schemes. Numerical models are used to resolve the large-scale flow. However, subgrid-scale parameterizations are for an estimation of small-scale properties (e.g., boundary layer turbulence and Convection, Clouds, radiation). Those have a significant influence on the resolved scale due to the complex nonlinear nature of the atmosphere. For the cloudy planetary boundary layer (PBL), it is fundamental to parameterize vertical turbulent fluxes and subgrid-scale condensation in a realistic manner. A parameterization based on the total energy–mass flux (TEMF) that unifies turbulence and moist Convection components produces a better result than other PBL schemes. Thus, we present our optimization results for the TEMF PBL scheme. Those optimizations included vectorization of the code to utilize multiple vector units inside each processor code. The optimizations improved the performance of the original TEMF code on Xeon Phi 7120P by a factor of ${\bf 25}.{\bf 9} \times $ . Furthermore, the same optimizations improved the performance of the TEMF on a dual socket configuration of eight-core Intel Xeon E5-2670 CPUs by a factor of ${\bf 8}.{\bf 3} \times $ compared to the original TEMF code.

  • using intel xeon phi to accelerate the wrf temf planetary boundary layer scheme
    Data Compression Communications and Processing, 2014
    Co-Authors: Jarno Mielikainen, Bormin Huang, Allen Huang
    Abstract:

    The Weather Research and Forecasting (WRF) model is designed for numerical weather prediction and atmospheric research. The WRF software infrastructure consists of several components such as dynamic solvers and physics schemes. Numerical models are used to resolve the large-scale flow. However, subgrid-scale parameterizations are for an estimation of small-scale properties (e.g., boundary layer turbulence and Convection, Clouds, radiation). Those have a significant influence on the resolved scale due to the complex nonlinear nature of the atmosphere. For the cloudy planetary boundary layer (PBL), it is fundamental to parameterize vertical turbulent fluxes and subgrid-scale condensation in a realistic manner. A parameterization based on the Total Energy – Mass Flux (TEMF) that unifies turbulence and moist Convection components produces a better result that the other PBL schemes. For that reason, the TEMF scheme is chosen as the PBL scheme we optimized for Intel Many Integrated Core (MIC), which ushers in a new era of supercomputing speed, performance, and compatibility. It allows the developers to run code at trillions of calculations per second using the familiar programming model. In this paper, we present our optimization results for TEMF planetary boundary layer scheme. The optimizations that were performed were quite generic in nature. Those optimizations included vectorization of the code to utilize vector units inside each CPU. Furthermore, memory access was improved by scalarizing some of the intermediate arrays. The results show that the optimization improved MIC performance by 14.8x. Furthermore, the optimizations increased CPU performance by 2.6x compared to the original multi-threaded code on quad core Intel Xeon E5-2603 running at 1.8 GHz. Compared to the optimized code running on a single CPU socket the optimized MIC code is 6.2x faster.

Hunglung Allen Huang - One of the best experts on this subject based on the ideXlab platform.

  • optimizing total energy mass flux temf planetary boundary layer scheme for intel s many integrated core mic architecture
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2015
    Co-Authors: Jarno Mielikainen, Bormin Huang, Hunglung Allen Huang
    Abstract:

    In order to make use of the ever-improving microprocessor performance, the applications must be modified to take advantage of the parallelism of today’s microprocessors. One such application that needs to be modernized is the weather research and forecasting (WRF) model, which is designed for numerical weather prediction and atmospheric research. The WRF software infrastructure consists of several components such as dynamic solvers and physics schemes. Numerical models are used to resolve the large-scale flow. However, subgrid-scale parameterizations are for an estimation of small-scale properties (e.g., boundary layer turbulence and Convection, Clouds, radiation). Those have a significant influence on the resolved scale due to the complex nonlinear nature of the atmosphere. For the cloudy planetary boundary layer (PBL), it is fundamental to parameterize vertical turbulent fluxes and subgrid-scale condensation in a realistic manner. A parameterization based on the total energy–mass flux (TEMF) that unifies turbulence and moist Convection components produces a better result than other PBL schemes. Thus, we present our optimization results for the TEMF PBL scheme. Those optimizations included vectorization of the code to utilize multiple vector units inside each processor code. The optimizations improved the performance of the original TEMF code on Xeon Phi 7120P by a factor of ${\bf 25}.{\bf 9} \times $ . Furthermore, the same optimizations improved the performance of the TEMF on a dual socket configuration of eight-core Intel Xeon E5-2670 CPUs by a factor of ${\bf 8}.{\bf 3} \times $ compared to the original TEMF code.

Frédérique Cheruy - One of the best experts on this subject based on the ideXlab platform.

  • improved near surface continental climate in ipsl cm6a lr by combined evolutions of atmospheric and land surface physics
    Journal of Advances in Modeling Earth Systems, 2020
    Co-Authors: Frédérique Cheruy, Agnès Ducharne, Frédéric Hourdin, Ionela Musat, Étienne Vignon, Guillaume Gastineau, Vladislav Bastrikov, Nicolas Vuichard, Binta Diallo, Jean-louis Dufresne
    Abstract:

    This work is motivated by the identification of the land-atmosphere interactions as one of the key sources of uncertainty in climate change simulations. It documents new developments in related processes, namely, boundary layer/Convection/Clouds parameterizations and land surface parameterization in the Earth System Model of the Institut Pierre Simon Laplace (IPSL). Simulations forced by prescribed oceanic conditions are produced with different combinations of atmospheric and land surface parameterizations. They are used to explore the sensitivity to the atmospheric physics and/or soil physics of • major biases in the near surface variables over continents, • the energy and moisture coupling established at the soil/atmosphere interface in not too wet (energy limited) and not too dry (moisture limited) soil moisture regions also known as transition or "hot-spot" regions, • the river runoff at the outlet of major rivers. The package implemented in the IPSL-Climate Model for the Phase 6 of the Coupled Models Intercomparison Project (CMIP6) allows us to reduce several biases in the surface albedo, the snow cover, and the continental surface air temperature in summer as well as in the temperature profile in the surface layer of the polar regions. The interactions between soil moisture and atmosphere in hotspot regions are in better agreement with the observations. Rainfall is also significantly improved in volume and seasonality in several major river basins leading to an overall improvement in river discharge. However, the lack of consideration of floodplains and human influences in the model, for example, dams and irrigation, impacts the realism of simulated discharge. Plain Language Summary Land surface-atmosphere interactions play an essential role in the climate system. They strongly modulate the regional climates and have impacts on the global scale for instance through freshwater release into the oceans. Climate hazards (heat waves, droughts) and their impacts on populations also strongly depend on interactions between land and atmosphere and on their evolution with climate change. Climate models are precious tools to investigate how the Earth climate behaves. The sixth phase of the Climate Model Intercomparison Project (CMIP6) provides important tools to measure the progress and address the remaining open questions regarding the continental climate modeling. The representation of the land-atmosphere coupled system by the IPSL-Climate Model involved in CMIP6 is thoroughly evaluated against observations and compared with simulations using the CMIP5 version. Several biases concerning the temperature over land and over the ice sheets and with the snow cover are significantly reduced. Numerous improvements were made developping advanced parameterizations and tuning of the radiation and of the turbulent mixing in the atmospheric model. The realism of the seasonal