以北京市观象台2010年8月、2011年8月每日3次(08:00,14:00,20:00,北京时,下同)L波段探空秒间隔数据为实况,对BJ RUC系统(rapid updated cycle system for the Beijing area)分析和预报边界层性能进行了初步评估。结果表明:BJ...以北京市观象台2010年8月、2011年8月每日3次(08:00,14:00,20:00,北京时,下同)L波段探空秒间隔数据为实况,对BJ RUC系统(rapid updated cycle system for the Beijing area)分析和预报边界层性能进行了初步评估。结果表明:BJ RUC系统对北京地区夏季白天边界层的细致特征具有较好的预报能力,但也存在明显的系统性误差。08:00边界层偏冷;14:00和20:00 1 km以下的边界层则显著偏暖,边界层内明显偏湿。整体上模式对边界层内温度、湿度的预报误差均高于自由大气。该系统对北京地区边界层内早晨(08:00)从夜间山风向白天谷风环流过渡、午后(14:00)到日落后(20:00)1500 m以下盛行西南偏南气流的日变化特征具有较强的预报能力。系统预报的14:00边界层顶高度与评估时段内实际对流边界层高度的变化趋势一致。但预报的对流边界层顶偏高,这与BJ RUC系统采用YSU边界层参数化方案的垂直混合更强有关。展开更多
Based on turbulence theory,a 1.5-order closure turbulence model is established.The model incorporating with theground surface energy budget equation is constructed by means of a vertical one-dimensional(1-D)40-level... Based on turbulence theory,a 1.5-order closure turbulence model is established.The model incorporating with theground surface energy budget equation is constructed by means of a vertical one-dimensional(1-D)40-levelgrid-mesh.The numerical results reveal the 24-h evolution of the clear planetary boundary layer comparing with theWangara boundary layer data of days 33—34.The model also takes into account some physical processes of radiativetransfer and baroclinicity,revealing some important characteristics observed in the boundary layer,especially for theevolution of the mixed layer and low-level jet.The calculated results are in good agreement with the observational data.On the other hand,we also run the high-resolution model of the planetary boundary layer in the Mesoscale Model Ver-sion 4(MM4)with the same physical processes and initial conditions.The results show that the high-resolution modelcan not reveal those important characteristics as the 1.5-order closure model did.In general,it is shown that the 1.5-or-der closure turbulence model based on turbulence theory is better in rationality and reality.展开更多
Vertical profiles of virtual potential temperature,specific humidity,temperature at saturation points,moist staticenergies along with parcel condensing levels using minisonde data are analysed for two stations throu... Vertical profiles of virtual potential temperature,specific humidity,temperature at saturation points,moist staticenergies along with parcel condensing levels using minisonde data are analysed for two stations through which a mon-soon depression passed.The height of the cloud base came down as low as 910 hPa level from 835 hPa.Equivalent po-tential temperature increased in the vertical profile as well as in the conserved variable diagram as the depression ap-proached the station.Parcel condensing levels showed clearly inversion top and cloud top but not in all cases.Moist stat-ic energy showed an increase upto 10 kJ/kg as the depression approached.展开更多
In this paper, the eddy coefficient and the treatment for dividing layers of Estoque’s numerical model in modernPBL dynamics have been applied to derive order-zero and order-one analytic solutions over large-scale ... In this paper, the eddy coefficient and the treatment for dividing layers of Estoque’s numerical model in modernPBL dynamics have been applied to derive order-zero and order-one analytic solutions over large-scale topography,the solutions are used to obtain the divergence and vertical velocity, improving the previous results.展开更多
文摘以北京市观象台2010年8月、2011年8月每日3次(08:00,14:00,20:00,北京时,下同)L波段探空秒间隔数据为实况,对BJ RUC系统(rapid updated cycle system for the Beijing area)分析和预报边界层性能进行了初步评估。结果表明:BJ RUC系统对北京地区夏季白天边界层的细致特征具有较好的预报能力,但也存在明显的系统性误差。08:00边界层偏冷;14:00和20:00 1 km以下的边界层则显著偏暖,边界层内明显偏湿。整体上模式对边界层内温度、湿度的预报误差均高于自由大气。该系统对北京地区边界层内早晨(08:00)从夜间山风向白天谷风环流过渡、午后(14:00)到日落后(20:00)1500 m以下盛行西南偏南气流的日变化特征具有较强的预报能力。系统预报的14:00边界层顶高度与评估时段内实际对流边界层高度的变化趋势一致。但预报的对流边界层顶偏高,这与BJ RUC系统采用YSU边界层参数化方案的垂直混合更强有关。
基金Acknowledgements. Part of this study was done during the first author's Ph. D studies at the Institute of Atmospheric Physics in China. Two anonymous reviewers provided constructive comments to an early manuscript of this study. The authors thank Marcela Ulate Medrano for providing the WRF latent heating data. This study was supported by National Science Foundation of U.S.A. (Grant No. ATM0739402) and the National Natural Science Foundation of China (Grant Nos. U0833602 and 40905035).
文摘 Based on turbulence theory,a 1.5-order closure turbulence model is established.The model incorporating with theground surface energy budget equation is constructed by means of a vertical one-dimensional(1-D)40-levelgrid-mesh.The numerical results reveal the 24-h evolution of the clear planetary boundary layer comparing with theWangara boundary layer data of days 33—34.The model also takes into account some physical processes of radiativetransfer and baroclinicity,revealing some important characteristics observed in the boundary layer,especially for theevolution of the mixed layer and low-level jet.The calculated results are in good agreement with the observational data.On the other hand,we also run the high-resolution model of the planetary boundary layer in the Mesoscale Model Ver-sion 4(MM4)with the same physical processes and initial conditions.The results show that the high-resolution modelcan not reveal those important characteristics as the 1.5-order closure model did.In general,it is shown that the 1.5-or-der closure turbulence model based on turbulence theory is better in rationality and reality.
文摘 Vertical profiles of virtual potential temperature,specific humidity,temperature at saturation points,moist staticenergies along with parcel condensing levels using minisonde data are analysed for two stations through which a mon-soon depression passed.The height of the cloud base came down as low as 910 hPa level from 835 hPa.Equivalent po-tential temperature increased in the vertical profile as well as in the conserved variable diagram as the depression ap-proached the station.Parcel condensing levels showed clearly inversion top and cloud top but not in all cases.Moist stat-ic energy showed an increase upto 10 kJ/kg as the depression approached.
基金This work was supported by National Natural Science Foundation of China
文摘 In this paper, the eddy coefficient and the treatment for dividing layers of Estoque’s numerical model in modernPBL dynamics have been applied to derive order-zero and order-one analytic solutions over large-scale topography,the solutions are used to obtain the divergence and vertical velocity, improving the previous results.
基金Acknowledgments This research is partially supported by National Natural Science Foundation of China (NSFC) under Grant Nos. 41175007 and 40905060 the Project of Scientific and Technological New Star of Beijing under Grant No. 2010B029+1 种基金 the National Basic Research Program of China (2011CB403401) China Meteorological Admin- istration (CMA) under Grant No. GYHY200806001-4.