黄土高原地区PWV影响因素分析及精度评定

Analysis of Influencing Factors and Accuracy Evaluation of PWV in the Loess Plateau

    摘要
  • 摘要: 大气水汽是对流层的重要组成部分之一，研究影响水汽的因素及精度具有重要意义。主要研究黄土高原地区大气可降水量（precipitable water vapor, PWV）的影响因素，并对其实际精度进行评估。首先，对ERA5（the fifth-generation atmospheric reanalysis data of ECMWF）的气压、气温数据和全球导航卫星系统（global navigation satellite system, GNSS）获取的天顶对流层延迟（zenith troposphere delay, ZTD）进行评定；然后，依据ERA5的气压、气温数据和GNSS的ZTD数据计算1 h分辨率的PWV，并利用误差传播理论推导PWV的理论误差; 最后, 与PWV实际计算误差进行对比，分析黄土高原地区PWV的精度。结果表明，基于GAMIT/GLOBK软件获得的GNSS ZTD与PANDA软件解算的GNSS ZTD差值的均方根（root mean square, RMS）和Bias分别为4.05 mm和-0.46 mm；ERA5气压和气温的平均RMS和Bias分别为3.36 hPa/1.97 K和-0.01 ‍hPa/0.04 K；黄土高原地区PWV的理论误差为1.51 mm，实际误差为1.94 mm。计算得到的PWV精度较高，对水汽分布以及气候监测的研究具有重要意义。

     

    Abstract:
      Objectives  Atmospheric water vapor is one of the important components in troposphere. It is of great significance to study the factors and accuracy of influencing water vapor. This paper mainly studies the influencing factors of precipitable water vapor (PWV) in the Loess Plateau and evaluates its actual accuracy.
      Methods  Firstly, the pressure, temperature data of the fifth-generation atmospheric reanalysis data of ECMWF(ERA5)and global navigation satellite system(GNSS) derived zenith troposphere delay (ZTD) are evaluated. Secondly, according to the pressure and temperature data of ERA5 and ZTD data of crustal movement observation network of China (CMONOC), the PWV with 1-hour time resolution is calculated, and the theoretical error of PWV is deduced by using error propagation theory, and then the accuracy of PWV in the Loess Plateau is analyzed by comparing with the actual calculation error of PWV.
      Results  The results show that the average root mean square(RMS) and bias of GNSS-derived ZTD calculated by GAMIT/GLOBK and PANDA are 4.05 mm and -0.46 mm, respectively. The average RMS and bias of ERA5-provided pressure and temperature are 3.36 hPa / 1.97 K and -0.01 hPa / 0.04 K, respectively. The theoretical error of PWV in the Loess Plateau is 1.51 mm, and the actual error is 1.94 mm.
      Conclusions  The accuracy of PWV calculated in this paper is high, which is of great significance to the investigation of water vapor distribution and climate monitoring.

     

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