地基GPS气象学研究的主要问题及最新进展

THE MAIN PROBLEMS AND NEW ADVANCES IN GROUND-BASED GPS METEOROLOGY

目前大多数映射函数在低高度角时精度都比较差 ,发展适应低高度角的映射函数 ,提高低高度角观测值的利用率 ,研究大气的水平梯度是目前地基GPS气象学的主要研究任务 ,发展随时空变化的动态映射函数也是国际上的一个主要研究问题。由于PWV不能提供水汽分布的三维信息 ,求定GPS信号斜路径方向上的水汽SWV ,以及利用SWV层析大气的垂直结构是目前国际上GPS气象学的研究前沿。文中总结了目前国际上SWV的求定及层析水汽三维结构的主要方法 ,及存在的问题。把GPS探测的水汽同化到数值天气预报中 ,以提高数值预报的能力是GPS气象学研究的目的 ,作者介绍了目前水汽在数值预报模型中的同化情况。

Because the deficiency of the most mapping functions at low cut off angles, it is necessary to develop new mapping functions so that the GPS observations at low cut off angles could be used effectively. The dynamic mapping functions with spatial and temporal variety are also needed for the adaptability. Though we can get PWV (precipitable water vapor) with high accuracy, but it cannot provide three-dimensional distribution of water vapor in atmosphere. It has been proved that slant water vapor(SWV) contains vertical information of water vapor. The vertical distribution can be retrieved by tomography using SWV. In this paper, the techniques of how to determine SWV and analyze the three dimensional distribution using SWV and the main current problems are introduced. The assimilation of water vapor retrieved from GPS observations into numerical weather forecast is the main object of GPS meteorology and the forecast can be improved. The progresses of assimilation at present are also reviewed .The developments of monitoring global climate change and atmosphere refraction environment using GPS are also described.