三种温湿参数下昆明准静止锋锋面位置及锋生函数诊断的对比分析

A Comparative Analysis of the Kunming Quasi-stationary Frontal Position and Frontogenesis Function with Three Different Temperature and Humidity Parameters

针对2008年1~2月昆明准静止锋天气过程,讨论了位温、相当位温和广义位温三个温湿参数及其对应的锋生函数,对比分析结果表明:(1)广义位温因其湿度因子权重过大,不适用于分析以温度梯度定义的昆明准静止锋锋面位置和强度;(2)理想状态下的干大气位温和饱和大气相当位温仅与气压和温度有关,均能较好地反映大气温度场特征,适用于昆明准静止锋的分析,比较而言相当位温对温度锋区的描述更为显著;(3)用位温或相当位温计算锋生函数所得结果直接表达了因温度场变化导致的锋面生消状况,而用广义位温计算锋生函数所得结果同时包含温度锋生(消)和湿度锋生(消)两种情况,不能简洁地判断昆明准静止锋锋面生消状况。

This paper discusses potential temperature（PT）, equivalent potential temperature（EPT）, generalized potential temperature（GPT）, and corresponding frontogenesis function during the weather process of Kunming quasi-stationary front（KQSF） in January and February 2008. Results are as follows.（1） Due to the large weighting factor of humidity in the GPT, it is not appropriate for analyzing the position and intensity of the KQSF, which is determined by temperature gradient.（2） In an ideal state, the dry atmospheric PT and the saturated atmospheric EPT are only related to temperature and pressure, and can better describe the characteristics of the atmospheric temperature field. Thus both PT and EPT can be applied for analyzing the KQSF, while the EPT can better describe temperature frontal zone.（3） Frontogenesis function calculated from PT or EPT can directly represent the situation of frontogenesis and frontolysis caused by changes in temperature,while the result of the GPT is able to indicate the temperature frontogenesis（frontolysis）and humidity frontogenesis（frontolysis）at the same time,yet it cannot be simply adopted to determine the front frontogenesis or frontolysis situation of the KQSF.