This paper examines the performance of an atmospheric general circulation model (AGCM) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of ...This paper examines the performance of an atmospheric general circulation model (AGCM) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). It is a spectral model truncated at R42(2.8125°long×1.66°lat) resolution and with nine vertical levels, and referred to as R42L9/LASG hereafter. It is also the new version of atmospheric component model R15L9 of the global ocean-atmosphere-land system (GOALS/LASG). A 40-year simulation in which the model is forced with the climatological monthly mean sea surface temperature is compared with the 40-year (1958-97) U.S. National Center for Environmental Prediction (NGEP) global reanalysis and the 22-year (1979-2000) Xie-Arkin monthly precipitation climatology. The mean DJF and JJA geographical distributions of precipitation, sea level pressure, 500-hPa geopotential height, 850-hPa and 200-hPa zonal wind, and other fields averaged for the last 30-year integration of the R42L9 model are analyzed. Results show that the model reproduces well the observed basic patterns, particularly precipitation over the East Asian region. Comparing the new model with R15L9/LASG, the old version with coarse resolution (nearly 7.5°long×4.5°lat), shows an obvious improvement in the simulation of regional climate, especially precipitation. The weaknesses in simulation and future improvements of the model are also discussed.展开更多
Considerable spring precipitation occurs over South China(SC),a region that is adjacent to large-scale Asian topography and oceans.Its reasonable simulation is crucial for improving regional climate predictability.Thi...Considerable spring precipitation occurs over South China(SC),a region that is adjacent to large-scale Asian topography and oceans.Its reasonable simulation is crucial for improving regional climate predictability.This study investigates spring precipitation biases over SC and their possible causes in atmosphere-only and coupled Flexible Global Ocean–Atmosphere–Land System finite-volume version 3(FGOALS-f3) models with different horizontal resolutions.The performance of spring precipitation simulation over SC varies across different FGOALS-f3 model versions,with the best reproducibility in the high-resolution coupled model(25 km).In the low-resolution atmosphere-only model(100–125 km),the precipitation dry bias over SC is closely linked to overestimated surface sensible forcing over the eastern Tibetan Plateau(TP),which weakens the subtropical anticyclone over the western Pacific(SAWP) through regional circulation responses.By contrast,the high-resolution atmosphere-only model further amplifies surface thermal forcing in the Asian continents,causing intensified land–sea thermal contrast between the Southeast Asian continents and western Pacific,enhanced southerly winds and SAWP,and increased water vapor transport into SC.Meanwhile,the reduced middle–high level cold bias over 10°–30°N in the high-resolution atmosphere-only model intensifies the East Asian westerly jet and ascent over SC,leading to enhanced spring precipitation there.The high-resolution coupled model simulation not only reduces sea surface cold bias over the Bay of Bengal,thus intensifying the Indian–Burma trough and strengthening low-level water vapor transport into SC,but also enhances ascent over SC.As a result,the high-resolution coupled model better reproduces the magnitude and pattern of spring precipitation over SC than its atmosphere-only model.Compared with low-resolution models,the domain-mean spring precipitation dry bias decreases by 11.2% over SC in the high-resolution atmosphere-only model and by 35.9% in the coupled model.These results demonstrate that the high-resolution FGOALS-f3 models can improve simulations of the influencing atmospheric circulations and spring precipitation over SC.展开更多
文摘This paper examines the performance of an atmospheric general circulation model (AGCM) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). It is a spectral model truncated at R42(2.8125°long×1.66°lat) resolution and with nine vertical levels, and referred to as R42L9/LASG hereafter. It is also the new version of atmospheric component model R15L9 of the global ocean-atmosphere-land system (GOALS/LASG). A 40-year simulation in which the model is forced with the climatological monthly mean sea surface temperature is compared with the 40-year (1958-97) U.S. National Center for Environmental Prediction (NGEP) global reanalysis and the 22-year (1979-2000) Xie-Arkin monthly precipitation climatology. The mean DJF and JJA geographical distributions of precipitation, sea level pressure, 500-hPa geopotential height, 850-hPa and 200-hPa zonal wind, and other fields averaged for the last 30-year integration of the R42L9 model are analyzed. Results show that the model reproduces well the observed basic patterns, particularly precipitation over the East Asian region. Comparing the new model with R15L9/LASG, the old version with coarse resolution (nearly 7.5°long×4.5°lat), shows an obvious improvement in the simulation of regional climate, especially precipitation. The weaknesses in simulation and future improvements of the model are also discussed.
基金Supported by the National Key Research and Development Program of China (2022YFF0802003)National Natural Science Foundation of China (42288101,42275026,and 41975109)+2 种基金Natural Science Foundation of Yunnan Province (202301AV070001)Yunnan University Graduate Research and Innovation Fund (KC-22221894)National Key Scientific and Technological Infrastructure Project of China “Earth System Science Numerical Simulator Facility”(EarthLab)。
文摘Considerable spring precipitation occurs over South China(SC),a region that is adjacent to large-scale Asian topography and oceans.Its reasonable simulation is crucial for improving regional climate predictability.This study investigates spring precipitation biases over SC and their possible causes in atmosphere-only and coupled Flexible Global Ocean–Atmosphere–Land System finite-volume version 3(FGOALS-f3) models with different horizontal resolutions.The performance of spring precipitation simulation over SC varies across different FGOALS-f3 model versions,with the best reproducibility in the high-resolution coupled model(25 km).In the low-resolution atmosphere-only model(100–125 km),the precipitation dry bias over SC is closely linked to overestimated surface sensible forcing over the eastern Tibetan Plateau(TP),which weakens the subtropical anticyclone over the western Pacific(SAWP) through regional circulation responses.By contrast,the high-resolution atmosphere-only model further amplifies surface thermal forcing in the Asian continents,causing intensified land–sea thermal contrast between the Southeast Asian continents and western Pacific,enhanced southerly winds and SAWP,and increased water vapor transport into SC.Meanwhile,the reduced middle–high level cold bias over 10°–30°N in the high-resolution atmosphere-only model intensifies the East Asian westerly jet and ascent over SC,leading to enhanced spring precipitation there.The high-resolution coupled model simulation not only reduces sea surface cold bias over the Bay of Bengal,thus intensifying the Indian–Burma trough and strengthening low-level water vapor transport into SC,but also enhances ascent over SC.As a result,the high-resolution coupled model better reproduces the magnitude and pattern of spring precipitation over SC than its atmosphere-only model.Compared with low-resolution models,the domain-mean spring precipitation dry bias decreases by 11.2% over SC in the high-resolution atmosphere-only model and by 35.9% in the coupled model.These results demonstrate that the high-resolution FGOALS-f3 models can improve simulations of the influencing atmospheric circulations and spring precipitation over SC.
