贵州局地T_m模型的建立及时空变化特征分析

Establishment of the Local T_m Model in Guizhou and Its Spatio-Temporal Variation

加权平均温度(Tm)作为GNSS反演大气可降水量(PWV)的关键参量,具有较强的区域差异性和时域周期性。针对贵州地形起伏大和气候多变的特点,为提升贵州地区GNSS PWV的探测精度,本文基于欧洲中期天气预报中心发布的ERA5气象数据集,在揭示贵州局域Tm时域周期性的基础上,构建了一种适宜于贵州的高时空分辨率局域Tm格网模型(GZTm),并基于无线电探空站气象资料计算的Tm,对GZTm的精度进行了评价。结果表明:相比于Bevis模型和GPT2w模型,GZTm在贵阳站的精度分别提高了24.8%和1.0%,在威宁站则分别提高了10.4%和8.1%。此外,基于选定的15个ERA5格网点,本文还对贵州Tm的时空变化特征进行了初步分析,结果显示贵州Tm的季节差异明显,且与站点高程间密切相关,呈现出较强的区域差异性。

As a key parameter for GNSS inversion of precipitable water vapour (PWV), the weighted mean temperature (Tm) has strong regional differences and time-domain periodicity. In view of the characteristics of large topographic fluctuation and changeable climate in Guizhou, and in order to improve the precision of GNSS PWV within the Guizhou province, based on the ERA5 meteorological data set released by the European Centre for Medium-Range Weather Forecasts, a high spatio-temporal resolution Tm grid model (GZTm) suitable for Guizhou province was established on the basis of the revealing of the time domain periodicity for Guizhou Tm. Also, the precision of GZTm was evaluated by the Tm computed by the radiosonde dataset. Compared with the Bevis model and the GPT2w model, the results show that the precision of GZTm at Guiyang Station was increased by 24.8% and 1%, and 10.4% and 8.1% for Weining station, respectively. In addition, based on the selected 15 ERA5 grid points, this paper also conducts a preliminary analysis of the temporal and spatial characteristics of Guizhou Tm. The results show that Guizhou Tm owns obvious seasonal differences and is closely related to site elevation, showing strong regional differences.