【摘要】 利用常规气象观测资料、NCEP/NCAR北半球逐日再分析等资料,对2011年5月7日夜间至9日夜间宁夏久旱转首场透雨天气从环流演变及各种物理量场特征进行诊断分析。结果表明:透雨过程主要出现在大尺度环流形势由"西高东低"向"东高西低"环流转变过程中。透雨过程水汽主要来源于孟加拉湾及南海地区,孟加拉湾低槽的建立与东移西风槽的同位向叠加、700 hPa低涡发展东移、低层偏南急流的建立和水汽输送是久旱转透雨的主要条件和影响系统。久旱转雨时青藏高原和印缅槽指数及水汽、热力、动力等物理量场的转折特征明显。较大量级降水落区主要出现在低层风向风速辐合区、高能区、水汽通量散度辐合大值区以及低层辐合高层辐散的上升气流区内。更多还原

【Abstract】 The circulation evolution and various physical quantities characteristics during a weather process from long drought to the first soaking rain from May 7 to 9,2011 in Ningxia were analyzed by using the meteorological observations and NCEP/NCAR daily reanalysis data.The results show that the soaking rain occurred when the large-scale circulation transformed from "high in the west and low in the east" to "high in the east and low in the west".The water vapor came from the Bay of Bengal and the South China Sea region.The establishment of low trough in the Bay of Bengal and and overlap with westerly trough moving eastward,the developing and moving eastward of 700 hPa low vortex,and the establishment of low-level southerly jet and the moisture transportation resulted in the soaking rainfall in Ningxia.When the soaking rain occurred after long drought,the Qinghai-Tibet Plateau and the India-Burma indexes,moisture,heat,dynamics factors changed obviously.Larger rainfall area was mainly in the convergence zones of wind direction and speed on the low-level,the high energy regions,the big value zones of convergence of moisture flux divergence,and in the updraft regions where convergence in the low-level and divergence in the high-level.更多还原