利用小波变换对暴雨过程中GNSS气象要素的初步探索

利用小波分解对地基GNSS获取的可降水量(PWV)、气压和对流层延迟(ZTD)等时序进行处理和分析,以暴雨的实际降水量作为判别依据。研究结果表明,1 h间隔PWV与ZTD的小波高频分解系数接近,均能够从中提取暴雨预报特征信息,可用高频ZTD代替PWV进行小波分析;频率在30 min-1h之间的ZTD,预报时间信息应在第1~3层级进行搜寻,30 min以下频率的应在第3~5层级进行搜寻;db4小波分解PWV的暴雨预报阈值可设为-1.2,db4小波分解ZTD的暴雨预报阈值可设置为-0.007,db2小波分解ZTD的暴雨预报阈值可设为-0.01。

Preliminary Exploration of GNSS Meteorological Elements Using Wavelet Transform for Rainstorm Prediction

In this paper, we process and analyze, by wavelet decomposition, the time series of ground-based GNSS precipitable water vapor (PWV), atmospheric pressure and zenith tropospheric delay (ZTD). Based on the actual precipitation of rainstorms, the results show that the wavelet high-frequency decomposition coefficients of one-hour interval PWV and ZTD are close to each other, and the characteristic information of rainstorm prediction can be extracted from them. The high-frequency ZTD can be used to replace PWV for wavelet analysis. In ZTD with frequency between 30 minutes and 1 hour, the forecast time information should be searched at level 1~3, the frequency below 30 minutes should be searched at level 3~5, the forecast threshold of db4 wavelet decomposition PWV can be set to -1.2, the forecast threshold of db4 wavelet decomposition ZTD can be set to -0.007, and the forecast threshold of db2 wavelet decomposition ZTD can be set to -0.01.