Abstract:

By using the real － time observations and the physical quantities diagnosis，the causes of the regional extreme hot weather which occurred on July 26 to 31 in 2010 in Gansu Province were analyzed． The results show that the Qinghai － Tibetan high － pressure，middle － level continental high － pressure，low － level warm ridge of the plateau and the thermal low － pressure on the ground were the main influence systems of the continuous high temperature weather． The seasonal driving up northward and moving eastward of Tibetan high provided the large scale circulation condition for high temperature weather，and the Tibetan high and continental high pressure overlapped each other and formed a deep warm high pressure system，which resulted in radiation warming in clear zone and sinking adiabatic heating，these were the direct cause of the continuous hot weather． The development and moving eastward of the plateau warm ridge and the ground thermal low pressure caused ground temperature increase，which was an important reason for the continuous hot weather． In addition，low humidity，upper － level convergence，low － level divergence，the strong anticyclonic circulation with sinking motion，such dynamic field structure was an important condition for the formation of continuous hot weather．

Key words: continuous high temperature, affecting system, causes

摘要：

利用实时观测资料和物理量诊断对2010 年7 月26 ～ 31 日出现的甘肃区域性持续高温天气成因进行了分析。结果表明，对流层上层青藏高压、中层大陆高压、低层高原暖脊、地面热低压是造成这次持续高温天气的主要影响系统。青藏高压季节性北抬与东移，为持续高温天气的发生发展提供了大尺度环流背景条件; 青藏高压与大陆高压相互叠加形成深厚的暖性高压系统，由其引起的晴空区辐射增温和下沉绝热增温，是造成持续高温天气的直接原因; 高原暖脊和地面热低压发展东移引起的地面气温上升，是造成这次持续高温天气的重要原因; 另外，大气湿度小，上层辐合、低层辐散、强反气旋环流并伴有下沉运动的空间动力场结构是这次持续高温天气形成的重要条件。

关键词: 持续高温, 影响系统, 成因