获取GPS斜路径方向水汽含量算法

Operational Retrieval Method of Water Vapor along GPS Slant Path

获取高精度的GPS信号斜路径方向的水汽含量(SWV)数据,是获得测站周围水汽三维空间分布信息(水汽层析)的基础。目前计算SWV的方法有多种,但都不同程度地存在解算实时性差、解算精度不高、转换方程复杂不利于系统维护等缺点。本文计算SWV方法综合Bernese 5.0软件的双差处理流程和非差处理流程,分别获得相关站点的湿延迟梯度值和非差残差值,能近实时、高精度地反演SWV。使用该方法重新处理2007年微波辐射计和GPS对比观测试验数据,均方根误差小于4mm。证明应用该方法,地基GPS可较精确地反演三维水汽信息。

Remote sensing of water vapor amount along the slant path （SWV： Slant-path Water Vapor） using the ground-based GPS is the basis of getting the three-dimensional distribution （water vapor tomography） of water vapor on the immediate vicinity of the site. Many estimation methods have been developed in recent year, but more or less there are problems that hindered these method from putting into operational use, such as non-real-time resolving, low accuracy resolving result, or complex convert formula. By running the Bernese （version 5.0） double-difference processing script and the zero-difference processing script respectively, the key elements of no-isotropic component of water vapor in different azimuths above the GPS receiver, the wet gradient, and zero-differenced residuals are calculated. Then slant path water vapor amount can be accurately retrieved. In order to prove the accuracy of this new method, the observation data of a comparative observation experiment of slant-path water vapor between ground-based GPS and microwave radiometer conducted in summer 2007 are re-calculated. Comparison between GPS and MR shows that RMS is less than 4 ram, which means that the estimates of SWV can be used to retrieve the three dimensional information of water vapor.