GNSS和非实测气象参数的PWV反演方法及其精度评估

PWV Inversion Method Based on GNSS and Non-Measured Meteorological Parameters and Accuracy Evaluation

    摘要
  • 摘要: 水汽是大气的重要组成成分之一,其时空变化受气温、气压等多种气象因素的影响。因此,研究水汽反演影响因素对获取高精度水汽信息具有重要意义。以中国区域为例,研究利用全球导航卫星系统(global navigation satellite system,GNSS)和非实测气象数据（气温和气压）探测大气可降水量（precipitable water vapor, PWV）的方法。首先,对欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasting, ECMWF)第5代气候再分析数据集(ECMWF reanalysis v5, ERA5)提供的气温、气压和GNSS反演的天顶对流层延迟进行评估；其次,大气加权平均温度Tm是PWV反演的关键参数,对不同的Tm计算模型进行分析,确定中国区域最优Tm计算模型；最后,根据误差传播理论推导PWV的理论误差,利用非实测数据计算小时分辨率的PWV并进行精度评估。结果表明,利用GNSS获取的中国区域PWV与无线电探空/ERA5 PWV均有较好的时空一致性,降雨期间PWV的误差较非降雨期间稍大。所提方法获取的PWV理论误差为2.0 mm,实际误差为2.1 mm。因此,基于GNSS和非实测气象参数反演的PWV具有较高精度,对于研究中国区域水汽时空变化与分布具有重要意义。

     

    Abstract:
    Objectives Water vapor is one of the important components of the atmosphere, and its spatial and temporal variations are influenced by various meteorological factors such as temperature and pressure. Therefore, it is important to study the impact factors of water vapor inversion to obtain high-precision water vapor information.
    Methods We study the method of precipitable water vapor (PWV) detection using global navigation satellite system (GNSS) and non-measured meteorological data (temperature and pressure) in China. First, we evaluate the data of temperature and pressure provided by the European Centre for Medium-Range Weather Forecasting(ECMWF) reanalysis v5(ERA5), and the zenith troposphere delay retrieved by GNSS. Then, different calculation models of atmospheric weighted mean temperature, named Tm, are analyzed to determine the optimal calculation model in China region. Finally, the theoretical error of PWV is derived from the error propagation theory, and the hourly resolution PWV is calculated using the non-measured data, and then the accuracy is evaluated.
    Results The results show that the PWV obtained by GNSS in China region is in good spatial and temporal agreement with PWV derived from radio sounding and ERA5. The error of PWV during the rainfall period is slightly larger than that during the non-rainfall period. The theoretical error of PWV obtained by the proposed method is 2.0 mm, and the actual error is 2.1 mm.
    Conclusions The inversion of PWV based on GNSS and non-measured meteorological parameters has high accuracy and it is important for studying the spatial and temporal variation and distribution of water vapor in China region.

     

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