局地低温过程的特征分析及思考

Analysis and Thinking on Characteristics of Local Low Temperature Process

利用天津市13个国家级台站地面气象观测站数据资料,通过对2018年1月24日北辰区低温为全市之首天气过程的大尺度天气背景、低温动力和热力结构特征及其演变进行计算和分析,揭示了低温过程的形成和维持机制。结果表明:在地面冷高压及"大寒"节气之中的大尺度背景条件下,正北风向连续7个小时不变是低温过程的触发和加强机制;前期较低基础温度的存在有利于低温落区的建立;大气压强的升高和水汽压的降低是低温出现的原因;伴随湿度的增大和风向的改变是驱使低温结束的动力因子。

Based on the data of 13 national meteorological observation stations in Tianjin,the formation and maintenance mechanism of the low temperature process are revealed by calculating and analyzing the large-scale weather background,low-temperature dynamic and thermal structure characteristics and their evolution of the low temperature process in Beichen District on January 24,2018.The results are as follows:Firstly,under the large-scale background conditions of the ground cold high pressure and the solar term of"great cold",the constant northerly wind direction for seven consecutive hours is the triggering and strengthening mechanism of the low temperature process.Secondly,the lower base temperature in primary stage helps to establish low-temperature zone.Thirdly,the increase of atmospheric pressure and the decrease of water vapor pressure are the reasons for the occurrence of low temperature.Fourthly,the increase of humidity and the change of wind direction are the driving factors that terminate the low temperature process.