利用GABLS2客观评估GRAPES的边界层参数化方案
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摘要
根据GABLS(Global Energy and Water Cycle Experiment Atmospheric Boundary Layer Study)的第2个个例在GRAPES(Global and Regional Assimilation and PrEdiction System)单柱模式中构造了一个试验,用于检验规定的下垫面温度强迫条件下边界层过程的昼夜循环模拟能力。然后,将模拟结果与观测和大涡模拟结果进行了比较。结果表明,在规定的下垫面温度强迫下,GRAPES模拟的2m温度基本合理。然而,对于稳定条件(夜间),GRAPES模拟的向下的感热通量比观测的大,过估10m风速和摩擦速度,过估稳定边界层高度;对于不稳定条件(白天),GRAPES模拟的向上的感热通量比观测的小,低估不稳定边界层高度,低层位温偏冷。随后的敏感试验表明,减小边界层方案中的动量和热量的背景扩散值后,GRAPES模拟的稳定条件下的10m风速和摩擦速度,以及对流边界层的风和温度的廓线更接近大涡模拟。
Based on GABLS2(the 2nd case of Global Energy and Water Cycle Experiment Atmospheric Boundary Layer Study),a SCM(Single Column Model)experiment is constructed to evaluate the diurnal cycle of PBL(Planetary Boundary Layer)processes in GRAPES(Global and Regional Assimilation and PrEdiction System).Compared with observation and LES(Large Eddy Simulation),GRAPES simulates the 2-m temperature reasonably with the prescribed surface temperature forcing.However,it is found that the simulated downward sensible heat flux,10-m wind speed,surface friction velocity,and PBL height are overestimated under stable condition(during nighttime),while the simulated upward sensible heat flux and PBL height are underestimated under unstable condition(during daytime).Sensitivity experiment shows that the simulated 10-m wind speed and friction velocity in the stable boundary layer,as well as the profiles of wind and temperature in the convective boundary layer,are closer to LES if the background diffusion values are reduced.
Based on GABLS2(the 2nd case of Global Energy and Water Cycle Experiment Atmospheric Boundary Layer Study),a SCM(Single Column Model)experiment is constructed to evaluate the diurnal cycle of PBL(Planetary Boundary Layer)processes in GRAPES(Global and Regional Assimilation and PrEdiction System).Compared with observation and LES(Large Eddy Simulation),GRAPES simulates the 2-m temperature reasonably with the prescribed surface temperature forcing.However,it is found that the simulated downward sensible heat flux,10-m wind speed,surface friction velocity,and PBL height are overestimated under stable condition(during nighttime),while the simulated upward sensible heat flux and PBL height are underestimated under unstable condition(during daytime).Sensitivity experiment shows that the simulated 10-m wind speed and friction velocity in the stable boundary layer,as well as the profiles of wind and temperature in the convective boundary layer,are closer to LES if the background diffusion values are reduced.
引文
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[14]吴增茂,盛立芳.边界层大气大湍涡模拟(LES)方法的研究进展[J].气象科技,1998(2):7-12.
[2]雷雨顺.关于行星边界层顶现象[J].气象科技,1981(1):10-13.
[3]Holtslag A A M,Svensson G,Baas P,et al.Stable atmospheric boundary layers and diurnal cycles:challenges for weather and climate models[J].Bulletin of the American Meteorological Society,2013,94(11):1691-1706.
[4]Randall D A,Xu K M,Somerville R C J,et al.Single-column models and cloud ensemble models as links between observations and climate models[J].Journal of Climate,1996,9:1683-1697.
[5]薛纪善,陈德辉.数值预报系统GRAPES的科学设计与应用[M].北京:科学出版社,2008.
[6]Yang J L,Shen X S.The construction of SCM in GRAPES and its applications in two field experiment simulations[J].Advances in Atmospheric Sciences,2011,28(3):534-550.
[7]杨军丽,沈学顺.GRAPES单柱模式的试验研究[J].气象学报,2012,70:275-290.
[8]Zeng X B,Zhao M,Dickinson R E.Intercomparison of bulk aerodynamic algorithms for the computation of sea surface fluxes using TOGA COARE and TAO data[J].Journal of Climate,1998,11:2628-2644.
[9]Han J,Pan H L.Revision of convection and vertical diffusion schemes in the NCEP global forecast system[J].Weather and Forecasting,2011,26:520-533.
[10]Svensson G,Holtslag A A M,Kumar V,et al.Evaluation of the diurnal cycle in the atmospheric boundary layer over land as represented by a variety of single column models:The second GABLS experiment[J].Boundary-Layer Meteorology,2011,140:177-206.
[11]Kumar V,Svensson G,Holtslag A A M,et al.Impact of surface flux formulations and geostrophic forcing on large-eddy simulations of diurnal atmospheric boundary layer Flow[J].Journal of Applied Meteorology and Climatology,2010,49:1496-1516.
[12]Xu K M,Cederwall R T,Donner L J,et al.An intercomparison of cloud-resolving models with the Atmospheric Radiation Measurement summer 1997Intensive Observation Period data[J].Quarterly Journal of the Royal Meteorological Society,2002,128:593-624.
[13]Miao S G,Jiang W M.Large Eddy Simulation and Study of the Urban Boundary Layer[J].Advances in Atmospheric Sciences,2004,4:650-661.
[14]吴增茂,盛立芳.边界层大气大湍涡模拟(LES)方法的研究进展[J].气象科技,1998(2):7-12.