基于水汽垂直指数分布特征的PWV快速层析方法

A rapid PWV tomography technique based on water vapor vertical index distribution characteristics

GNSS水汽层析技术可以反演对流层水汽三维时空变化情况,但该技术比较复杂、运算量大,需要消耗一定的时间.故本文提出了一种利用地基GNSS反演的大气可降水量(precipitable water vapor,PWV)结合水汽在垂直方向上的指数分布特性来计算大气水汽三维分布的快速层析方法.该方法利用香港地区2022年8月的GNSS数据开展试验,与传统GNSS水汽层析方法进行对比.试验结果表明:两种方法的层析解算结果与探空数据均具有良好的一致性.虽然快速层析方法的解算结果在底层区域缺少一些水汽变化的细节信息,精度略逊于传统层析方法,但是在中、高层时精度会有所提升,层析解算结果良好.而且本文提出的快速层析方法无需构建和解算复杂的层析方程组,可以在大量GNSS测站参与水汽层析时减少计算复杂度,提升运算能力,同时可以更快地得到任意高度层的水汽密度,是一种简便、高效的层析方法.

Global navigation satellite system(GNSS)water vapor tomography technique can be used to retrieve the three-dimensional spatiotemporal variation of the atmospheric water vapor,but this technique is complicated,which requires a large number of computation and a certain amount of time.Therefore,this paper proposes a rapid tomography technique that uses the precipitable water vapor(PWV)from groundbased GNSS inversion and combines with the exponential distribution characteristics of water vapor in the vertical direction to calculate the three-dimensional distribution of atmospheric water vapor.In this paper,the GNSS data over Hong Kong area,China in August 2022 are used to carry out the experiment in which the rapid tomography technique are compared with the traditional GNSS tomography technique.The experimental results show that the two methods have good agreement with the radiosonde data.Due to lacking of some details of water vapor change in the bottom region,the accuracy of the rapid tomography technique in such region is slightly lower than that of the traditional tomography technique.However,the accuracy of the rapid tomography technique is improved in the middle and high levels,and the results of the tomography technique solution are good.In addition,the rapid tomography technique proposed in this paper does not need to construct and solve complex tomography equations,and can reduce the computational complexity and improve the computing power when a large number of GNSS stations participate in water vapor tomography technique.At the same time,the water vapor density at any level can be obtained rapidly,which is a simple and efficient tomography technique.