本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过...本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过程进行对比分析,发现5次降雪过程均为雨转雪过程,且持续时间相对较短,平原为雨夹雪或小雪到中雪,山区中到大雪,局部暴雪,数值模式预报的积雪深度与实况相差甚远;大尺度环流形势为500 hPa中低纬南支槽或弱波动配合700 hPa上的暖湿气流和中低层冷空气,造成边界层浅薄的冷垫上温度骤降而在短时间内形成降雪;相较于平原地区,高山区上空温度层结与最大上升运动中心的配置,有利于降雪粒子较长时间维持在有利于枝状雪花的形成区域,且高山区云底云水含量显著偏低、整层温度足够低,故高山区更利于暴雪的形成。展开更多
从资料搜集、同化系统、数值模式、检验评估四个方面介绍了东亚区域大气再分析技术研究及资料建设取得的进展。就观测资料而言,搜集了常规地面和探空、飞机观测、GPS、雷达、风廓线、卫星导风、野外试验等观测资料。其中未参加国际交换...从资料搜集、同化系统、数值模式、检验评估四个方面介绍了东亚区域大气再分析技术研究及资料建设取得的进展。就观测资料而言,搜集了常规地面和探空、飞机观测、GPS、雷达、风廓线、卫星导风、野外试验等观测资料。其中未参加国际交换的地面、探空资料、雷达等观测资料是本再分析资料构建的特色之一。针对Gridpoint Statistical Interpolation(GSI)同化系统,开展了该系统的本地化移植,并改进了GSI雷达径向风同化算子。对于Weather Research and Forecasting Model(WRF-ARW)模式,采用多组物理过程参数化方案组合,开展了批量个例和长时间模拟试验,并基于试验结果优化了模式的配置。检验评估系统采用NCAR模式评估系统MET。目前,再分析系统搭建及优化已完成,试验结果表明再分析系统初步具有在全球再分析的基础上提高区域再分析资料性能的能力,可将本再分析系统用于今后再分析数据的研制。展开更多
本文利用WRF(weather research and forecasting,天气预报)中尺度模式模拟2020年3月22日在浙江中部地区发生的一次超单体降雹过程,并结合多普勒雷达资料、常规天气资料分析了超单体的雷达回波特征、内部风场结构和云物理特征,研究冰雹...本文利用WRF(weather research and forecasting,天气预报)中尺度模式模拟2020年3月22日在浙江中部地区发生的一次超单体降雹过程,并结合多普勒雷达资料、常规天气资料分析了超单体的雷达回波特征、内部风场结构和云物理特征,研究冰雹形成、生长的机制。结果表明:本次超单体过程是在高空急流入口区右侧并配合低层冷切、配合较大的风切变、充足的不稳定能量等动力热力条件共同作用下发生发展,雷达图上有典型的钩状回波、高悬垂回波、有界弱回波区、三体散射长钉以及强烈发展的中气旋等特征。数值试验成功地再现了超单体的时空演变特征和垂直结构,降雹过程的雹粒子的增长和过冷却水密切相关,发展阶段的过冷却水、上升气流、雹三者处在统一位置,有利于冰雹的粒子增长;成熟阶段和减弱阶段则缺少这一配置,导致雹粒子缺少增长和补充,降雹趋于结束。展开更多
Based on the barotropic primitive equation in the polar coordinate system and the appropriate assumption, we obtained the mathematical equation of orographic forcing on unit mass air parcel. With the consideration of ...Based on the barotropic primitive equation in the polar coordinate system and the appropriate assumption, we obtained the mathematical equation of orographic forcing on unit mass air parcel. With the consideration of the frictional stress of the sea and land, supposing that parcel velocity in tropical cyclones is in linear variation and that the distribution of surface pressure is circular, a set of equations are derived, which describe the impact of orographic slope error, the central pressure error and position error of tropical cyclones on the wind field in the tropical cyclone. Typhoon Wipha (2007) is selected to verify the above interpretation method. The results show that the orographic slope, the frictional coefficient, the intensity and position of the cyclone are the important factors which have great influence on the interpretation of wind information about tropical cyclones. The dynamic interpretation method gives very good results, especially for the coastal area. It is applicable to improving the forecasts of the wind field in tropical cyclones.展开更多
Based on the primitive equations in polar coordinates and with the supposition that parcel velocity in tropical cyclones is in linear variation and that the distribution of surface pressure agrees with the Fujita form...Based on the primitive equations in polar coordinates and with the supposition that parcel velocity in tropical cyclones is in linear variation and that the distribution of surface pressure agrees with the Fujita formula, a set of equations are derived, which describe the impact of perturbations of central pressure, position of tropical cyclones, direction and velocity of movement of tropical cyclones on the wind field. It is proved that the second order approximation of the kinetic energy of tropical cyclones can be described by the equations under linear approximation. Typhoon Wipha (2007) is selected to verify the above interpretation method, and the results show that the interpretation method of the wind field could give very good results before the landfall of tropical cyclones, while making no apparent improvement after the landfall. The dynamical interpretation method in this paper is applicable to improving the forecasts of the wind field of tropical cyclones close to the coast.展开更多
Ensemble prediction experiments of the tracks of eight tropical cyclones occurring between 2004-2006 over the western Pacific have been performed by using MM5 with five cumulus parameterization schemes. The results sh...Ensemble prediction experiments of the tracks of eight tropical cyclones occurring between 2004-2006 over the western Pacific have been performed by using MM5 with five cumulus parameterization schemes. The results show that the predictions of the tracks of the tropical cyclones are sensitive to the selection of cumulus parameterization schemes. Each scheme has its own advantage and disadvantage, and the predications without cumulus parameterization schemes are not the worst, sometimes even better than the others. And all of the three ensemble methods improve the predictions of the tracks significantly, among which the ensemble method without parameterization schemes, the Grell, Betts-Miller and Kain-Fritsch schemes are the best.展开更多
文摘本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过程进行对比分析,发现5次降雪过程均为雨转雪过程,且持续时间相对较短,平原为雨夹雪或小雪到中雪,山区中到大雪,局部暴雪,数值模式预报的积雪深度与实况相差甚远;大尺度环流形势为500 hPa中低纬南支槽或弱波动配合700 hPa上的暖湿气流和中低层冷空气,造成边界层浅薄的冷垫上温度骤降而在短时间内形成降雪;相较于平原地区,高山区上空温度层结与最大上升运动中心的配置,有利于降雪粒子较长时间维持在有利于枝状雪花的形成区域,且高山区云底云水含量显著偏低、整层温度足够低,故高山区更利于暴雪的形成。
文摘从资料搜集、同化系统、数值模式、检验评估四个方面介绍了东亚区域大气再分析技术研究及资料建设取得的进展。就观测资料而言,搜集了常规地面和探空、飞机观测、GPS、雷达、风廓线、卫星导风、野外试验等观测资料。其中未参加国际交换的地面、探空资料、雷达等观测资料是本再分析资料构建的特色之一。针对Gridpoint Statistical Interpolation(GSI)同化系统,开展了该系统的本地化移植,并改进了GSI雷达径向风同化算子。对于Weather Research and Forecasting Model(WRF-ARW)模式,采用多组物理过程参数化方案组合,开展了批量个例和长时间模拟试验,并基于试验结果优化了模式的配置。检验评估系统采用NCAR模式评估系统MET。目前,再分析系统搭建及优化已完成,试验结果表明再分析系统初步具有在全球再分析的基础上提高区域再分析资料性能的能力,可将本再分析系统用于今后再分析数据的研制。
文摘本文利用WRF(weather research and forecasting,天气预报)中尺度模式模拟2020年3月22日在浙江中部地区发生的一次超单体降雹过程,并结合多普勒雷达资料、常规天气资料分析了超单体的雷达回波特征、内部风场结构和云物理特征,研究冰雹形成、生长的机制。结果表明:本次超单体过程是在高空急流入口区右侧并配合低层冷切、配合较大的风切变、充足的不稳定能量等动力热力条件共同作用下发生发展,雷达图上有典型的钩状回波、高悬垂回波、有界弱回波区、三体散射长钉以及强烈发展的中气旋等特征。数值试验成功地再现了超单体的时空演变特征和垂直结构,降雹过程的雹粒子的增长和过冷却水密切相关,发展阶段的过冷却水、上升气流、雹三者处在统一位置,有利于冰雹的粒子增长;成熟阶段和减弱阶段则缺少这一配置,导致雹粒子缺少增长和补充,降雹趋于结束。
基金National Basic Research Program of China (973 Program) (2009CB421505)major projects for science and technology development of Zhejiang province (2007C13G1610002)major promoting projects for new technology of China Meteorologycal Administration (09A13)
文摘Based on the barotropic primitive equation in the polar coordinate system and the appropriate assumption, we obtained the mathematical equation of orographic forcing on unit mass air parcel. With the consideration of the frictional stress of the sea and land, supposing that parcel velocity in tropical cyclones is in linear variation and that the distribution of surface pressure is circular, a set of equations are derived, which describe the impact of orographic slope error, the central pressure error and position error of tropical cyclones on the wind field in the tropical cyclone. Typhoon Wipha (2007) is selected to verify the above interpretation method. The results show that the orographic slope, the frictional coefficient, the intensity and position of the cyclone are the important factors which have great influence on the interpretation of wind information about tropical cyclones. The dynamic interpretation method gives very good results, especially for the coastal area. It is applicable to improving the forecasts of the wind field in tropical cyclones.
基金National Basic Research Program of China (973 Program) (2009CB421505)Major Projects for Science and Technology Development of Zhejiang Province (2007C13G1610002)Natural Science Foundation Project of Zhejiang Province(Y505286)
文摘Based on the primitive equations in polar coordinates and with the supposition that parcel velocity in tropical cyclones is in linear variation and that the distribution of surface pressure agrees with the Fujita formula, a set of equations are derived, which describe the impact of perturbations of central pressure, position of tropical cyclones, direction and velocity of movement of tropical cyclones on the wind field. It is proved that the second order approximation of the kinetic energy of tropical cyclones can be described by the equations under linear approximation. Typhoon Wipha (2007) is selected to verify the above interpretation method, and the results show that the interpretation method of the wind field could give very good results before the landfall of tropical cyclones, while making no apparent improvement after the landfall. The dynamical interpretation method in this paper is applicable to improving the forecasts of the wind field of tropical cyclones close to the coast.
基金Applied Research on Ensemble Forecast Using Multiple Parameterization Schemes, a NaturalScience Foundation project of Zhejiang Province (Y505286)
文摘Ensemble prediction experiments of the tracks of eight tropical cyclones occurring between 2004-2006 over the western Pacific have been performed by using MM5 with five cumulus parameterization schemes. The results show that the predictions of the tracks of the tropical cyclones are sensitive to the selection of cumulus parameterization schemes. Each scheme has its own advantage and disadvantage, and the predications without cumulus parameterization schemes are not the worst, sometimes even better than the others. And all of the three ensemble methods improve the predictions of the tracks significantly, among which the ensemble method without parameterization schemes, the Grell, Betts-Miller and Kain-Fritsch schemes are the best.
