地基GPS联合COSMIC掩星数据的水汽三维层析研究

Three-dimensional Water Vapor Tomography Using Ground-based GPS and COSMIC Occultation Observations

利用精密单点定位方法求取对流层斜路径方向的水汽含量,并用COSMIC掩星数据反算出的水汽密度值作为层析迭代的初始值,联合高斯加权距离拟合法进行三维水汽反演。对香港地区3d的GPS数据及相应的掩星数据进行试算,得到的水汽斜路径含量反演值与实测值差值小于0.87mm。将层析得到的水汽密度值与Radiosonde探空数据进行比较,二者差值的RMS小于1.1g.m-3,从而验证了该水汽三维层析方法的可行性。

A three-dimensional water vapor tomography algorithm is presented. The precise point positioning method is used to obtain the tropospheric slant water vapor. Then COSMIC occultation data is exploited to calculate the water vapor density to be used as initial values in the tomography iteration procedure. Afterwards, the inversion of three-dimensional water vapor is conducted using a fitting method of the Gaussian weighted distance. GPS datasets collected in Hong Kong on three days and the corresponding COSMIC occultation data are used for the algorithm test. RMS statistical value for differences between SWV derived from PPP and SWV derived by tomography is better than 0.87 mm. Comparing the water vapor density by tomography with that derived by the Radiosonde sounding data, their differences are typically below 1.1 g/m3 , which demonstrates the feasibility of the presented three-di- mensional tomography algorithm.