两种垂直分层方法对GPS水汽层析结果的影响

利用北京房山地区9个全球定位系统测站组成的实验站网，研究GPS水汽层析网格的划分方法，采取垂直均匀和垂直非均匀两种分层方法，分析GPS层析网格垂直分层对水汽层析结果的影响。结果表明：均匀和非均匀垂直分层方法得到的GPS水汽层析结果是可靠的，均可以与探空水汽结果进行比较。但垂直非均匀分层更符合大气水汽的实际分布特征，层析解算精度更高，尤其对测站高度差较小的GPS站网，尽量选择垂直非均匀分层方法。垂直均匀和垂直非均匀分层方法均可以为北京地区GPS层析网格垂直划分提供参考。

Effect of two vertical stratification methods of GPS tomography grid on GPS water vapor tomography result

A Global Positioning System (GPS) experimental station network including nine GPS stations in Fangshan district of Beijing was used for a study on GPS tomography grid. Effects of vertical stratification on the water vapor tomography results were analyzed in terms of methods of a vertically uniform and a non-uniform stratification. The results show that GPS water vapor tomography results obtained by two vertical stratification methods are reliable, and they are consistent with observed water vapor from radiosonde stations. However, tomography grid of vertically non-uniform stratification is more accurate compared with the observed atmospheric water vapor distribution, and the results are more precise compared with that of vertically non-uniform stratification, especially for GPS stations with less altitude differences. Thus, the vertically non-uniform stratification method should be chosen for these stations, although two methods both can provide references for the GPS tomography grid in Beijing.