为深入认识冷涡影响下不同类型强对流天气发生条件的差异,利用高空、地面气象观测资料,多普勒天气雷达和风廓线雷达资料,以及欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料ERA5...为深入认识冷涡影响下不同类型强对流天气发生条件的差异,利用高空、地面气象观测资料,多普勒天气雷达和风廓线雷达资料,以及欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料ERA5,对2016年6月13日和2018年6月13日山东两次同受冷涡影响但分别以短时强降水为主和风雹天气为主的不同类型强对流天气过程(分别简称“过程I”、“过程II”)进行了对比分析。结果表明:(1)以短时强降水为主的过程I,降水效率高,在其发展阶段回波质心高度低,成熟阶段形成强降水超级单体,最强降水出现在中气旋附近;以风雹天气为主的过程II,雷暴大风强度具有极端性,对流风暴发展深厚,60 dBZ以上强回波发展至-20℃层高度之上并持续,是产生大冰雹的重要原因。两次过程的强风均出现在弓形回波反射率因子核心前部和超级单体后侧下沉气流区。(2)过程I不稳定条件中等,西南气流配合湿区使低层增湿,950~850 hPa形成近饱和层并增厚,干层位于500 hPa以上,构成上干下湿层结,对流在地面辐合线和地面湿舌顶端叠加处触发;过程II热力和动力不稳定强,中空急流与800~600 hPa的显著干层为雷暴大风和冰雹的形成提供了有利条件,触发抬升系统是暖锋,比过程I更深厚。环境条件的差异决定了两次过程天气类型的差异。展开更多
The effects of vertical wind shear on tropical cyclone(TC) intensity change are examined based on the TC data from the China Meteorological Administration and the NCEP reanalysis daily data from 2001 to 2006.First,the...The effects of vertical wind shear on tropical cyclone(TC) intensity change are examined based on the TC data from the China Meteorological Administration and the NCEP reanalysis daily data from 2001 to 2006.First,the influence of wind shear between different vertical levels and averages in different horizontal areas are compared.The results indicate that the effect of wind shear between 200 and 850 hPa averaged within a 200-800 km annulus on TC intensity change is larger than any other calculated vertical wind shear.High-latitude and intense TCs tend to be less sensitive to the effects of VWS than low-latitude and weak TCs.TCs experience time lags between the imposition of the shear and the weakening in TC intensity.A vertical shear of 8-9 m/s(9-10 m/s) would weaken TC intensity within 60 h(48 h).A vertical shear greater than 10 m/s would weaken TC intensity within 6 h.Finally,a statistical TC intensity prediction scheme is developed by using partial least squares regression,which produces skillful intensity forecasts when potential predictors include factors related to the vertical wind shear.Analysis of the standardized regression coefficients further confirms the obtained statistical results.展开更多
文摘为深入认识冷涡影响下不同类型强对流天气发生条件的差异,利用高空、地面气象观测资料,多普勒天气雷达和风廓线雷达资料,以及欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料ERA5,对2016年6月13日和2018年6月13日山东两次同受冷涡影响但分别以短时强降水为主和风雹天气为主的不同类型强对流天气过程(分别简称“过程I”、“过程II”)进行了对比分析。结果表明:(1)以短时强降水为主的过程I,降水效率高,在其发展阶段回波质心高度低,成熟阶段形成强降水超级单体,最强降水出现在中气旋附近;以风雹天气为主的过程II,雷暴大风强度具有极端性,对流风暴发展深厚,60 dBZ以上强回波发展至-20℃层高度之上并持续,是产生大冰雹的重要原因。两次过程的强风均出现在弓形回波反射率因子核心前部和超级单体后侧下沉气流区。(2)过程I不稳定条件中等,西南气流配合湿区使低层增湿,950~850 hPa形成近饱和层并增厚,干层位于500 hPa以上,构成上干下湿层结,对流在地面辐合线和地面湿舌顶端叠加处触发;过程II热力和动力不稳定强,中空急流与800~600 hPa的显著干层为雷暴大风和冰雹的形成提供了有利条件,触发抬升系统是暖锋,比过程I更深厚。环境条件的差异决定了两次过程天气类型的差异。
基金National Natural Science Foundation of China(41405060,41475082,41305049,41275067,41475059)
文摘The effects of vertical wind shear on tropical cyclone(TC) intensity change are examined based on the TC data from the China Meteorological Administration and the NCEP reanalysis daily data from 2001 to 2006.First,the influence of wind shear between different vertical levels and averages in different horizontal areas are compared.The results indicate that the effect of wind shear between 200 and 850 hPa averaged within a 200-800 km annulus on TC intensity change is larger than any other calculated vertical wind shear.High-latitude and intense TCs tend to be less sensitive to the effects of VWS than low-latitude and weak TCs.TCs experience time lags between the imposition of the shear and the weakening in TC intensity.A vertical shear of 8-9 m/s(9-10 m/s) would weaken TC intensity within 60 h(48 h).A vertical shear greater than 10 m/s would weaken TC intensity within 6 h.Finally,a statistical TC intensity prediction scheme is developed by using partial least squares regression,which produces skillful intensity forecasts when potential predictors include factors related to the vertical wind shear.Analysis of the standardized regression coefficients further confirms the obtained statistical results.
