Abstract: The three-dimensional water vapor field is obtained using Monte Carlo tomography algorithm based on the small-scale network of ground-based GPS. After the proof of the accuracy of the tomography water vapor field through the comparison between the profiles from the radiosonde and tomography field, the three-dimensional water vapor field and the data of Weather Radar are used to study the variation of the water vapor in the strong convection and heavy precipitation processes which took place on July 29, 2011. For the first time, the authors propose the continuous change and fine structure of the small-scale water vapor field during the convective processes. For local convection process, the tomography vapor field can capture the water vapor enrichment phenomenon and provide its location 20 minutes ahead the precipitation and it is an indication to the precipitation forecast. For rainstorm process, the water vapor field can explicitly show the position and intensity of the vapor transport source which meet well with the conclusion from the analysis of weather radar and meteorological situation.

Key words: tomography, water vapor field, precipitation

摘要： 利用小尺度GPS网络, 使用蒙特卡罗GPS水汽层析算法获取高时空分辨率的水汽场, 并通过与探空资料对比验证层析水汽场具有理想的精度。结合GPS三维层析水汽场与天津气象雷达资料, 分析2011年7月29日大暴雨过程, 首次给出小尺度水汽场在强对流过程中连续的变化过程以及精细结构。对于局地的对流过程, 三维层析水汽场能够在降水发生前约20分钟捕捉水汽在空中的富集现象并给出相应位置, 对降水预报具有指示作用。对于大范围强降水过程, 水汽场能够明确地给出水汽输送来源的位置和强度, 与天气形势分析和雷达气象分析的结论一致。

关键词: 层析, 水汽场, 降水