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

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 ground-based 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.