南疆夏季不同降水类型预报及递进式服务思考

Forecast and Progressive Service of Different Precipitation Types in Summer of Southern Xinjiang

南疆作为气候干旱区,夏季常发生不同类型的降水,2013年6月南疆短历时、高强度、小范围降水事件和2016年8月长时间、持续型、大范围降水事件在预报和服务方面有较大差异。分析两次强降水事件,南亚高压双体型是南疆夏季强降水的大尺度环流背景。高强度降水事件环流经向度大,高、中、低纬低槽同位相叠加,是造成强降水的直接影响系统;持续型强降水事件在500 hPa高空平均环流场上显示,欧亚范围内中高纬度地区为两脊一槽的经向环流,西西伯利亚至中亚地区的副热带大槽呈东北—西南向分布,长波槽底伸至38°N附近,是造成持续型强降水和气温持续下降或偏低的直接影响系统。本文在预报基础上,从气象服务的角度出发,结合长期、中短期、短时临近天气预报,重点分析在时间、范围和强度等方面存在明显差异的不同类型强降水过程中气象服务的递进式思路和方法,为精细化气象服务提供参考。

As an arid climate zone, different precipitation types often occur during summertime in southern Xinjiang. There are significant differences between precipitation events with short duration,high intensity and small scale in southern Xinjiang in June 2013 and long duration, and those in August 2016 with persistent and large scale in terms of forecast and service. Two-body type South Asia high pressure is the large-scale circulation background of heavy precipitation in summer of southern Xinjiang. Same phase superposition trough in high, medium and low latitude is a direct influence system of high intensity precipitation event, and the subtropical trough from western Siberia to central Asia near to the 38 0 N is thedirect influence system of continuous heavy rain events and continues declining of temperature. Based on the forecast and from the perspective of meteorological service, this study mainly focus on analyzing the strategy and methods of meteorological service during various heavy rains with obvious temporal and spatial as well as strength differences with prediction time scales consist of long-term, medium-term and short-term to provide reference for fine weather service.