NCEP/NCAR FNL资料在强对流天气中可信度的初步分析

Confidence Analysis of NCEP/NCAR FNL Data on Strong Convective Weather

基于NCEP/NCAR FNL(1°×1°)资料已成为研究强对流天气触发机制、演变等特征的基础资料,有必要分析该资料在强对流天气中的可信度。利用山西岢岚地区2005-2014年共414个强对流天气日的NCEP/NCAR FNL(1°×1°)资料与探空资料,采用偏差、绝对差、相关系数和偏差区间占有率的统计方法,对常用的常规气象要素、诊断量进行统计分析,结果表明:1)在常规气象要素中,温度的可信度最高,而相对湿度的可信度最低,纬向风和经向风的可信度相差不大,均略低于温度的可信度。2)总体上,诊断量的可信度不如常规气象要素的,其中,K指数偏差值在[-5,5]内占总数的57. 25%,沙氏指数SI偏差值在[-3,3]内占总数的75. 12%,对流有效位能CAPE偏差值在[-100,100]内占总数的78. 26%,风暴强度指数SSI偏差值在[-10,10]内占总数的62. 08%。因此,虽然NCEP/NCAR FNL资料中的常规气象要素可信度较高,但与强对流天气存在紧密联系的诊断量却存在较大偏差和绝对差,其可信度较低,若以其进行强对流天气机理的诊断分析,需注意该资料的这种特征。

The NCEP/NCAR FNL reanalysis data （1°×1°） has become a basic data to research the generation mechanism and evolution characteristics of strong convective weather.Therefore,it is necessary to analyze the credibility of the data.In the paper,by using NCEP/NCAR FNL data（1°×1°） and radiosonde data in 414 strong convective weather days during 20052014 in Kelan, Shanxi province, the conventional meteorological elements （temperature,relative humidity,zonal wind and meridional wind）and diagnostic physical quantity （K index,SI index,CAPE,et al.） were discussed by using statistical analysis methods including deviation,absolute difference,correlation coefficient and the occurrence rates of deviation range etc.Results were as follows.1）In conventional meteorological elements, the temperature had highest reliability, while relative humidity had poor reliability,the reliability of the zonal wind and meridional wind were almost the same,and were slightly lower than temperature. 2）As a whole,the reliability of diagnostic physical quantity were lower than conventional meteorological elements.And the deviation of K index in [-5,5],SI index in [-3,3],CAPE in [-100,100] and SSI in [-10,10] respectively accounted for 57.25%,75.12%,78.26% and 62.08% of the total.Therefore, although conventional meteorological elements in NCEP/NCAR FNL data had high reliability, the diagnostic physical quantity that were closely related to strong convective weather had high deviation and absolute difference,indicating poor reliability,and if analysis of the mechanism about strong convection weather is based on such data,it needs to pay attention to the characteristics of the data.