卫星跟踪卫星技术反演局部地表物质迁移的MASCON方法研究

MASCON方法是直接利用GRACE任务的卫星跟踪卫星技术研究地表浅层物质运动的一种有效技术手段.该方法相较Stokes球谐系数法在一定程度上克服了时变信号的滤波问题,能有效解决该方法时变重力场的南北条带效应.本文在对现有MASCON方法深入研究的基础上对其进行了改进,提出引入卫星精密轨道作为观测值,联合高低跟踪和低低跟踪两类观测数据,实现MASCON参数及有关动力学模型参数求解的思路,在不影响时变信号主要由星间距离变率观测值提供的前提下,采用方差分量估计方法合理定权,充分利用轨道数据的绝对基准作用,用一种改进的途径实现了MASCON方法.利用2008年GRACE的卫星重力观测数据,获得了亚马逊地区的地表物质迁移结果,并与GLDAS水文模型、CSR RL05球谐系数和JPL MASCON方法计算的水储量变化进行比较,表明一致性较好,验证了本文所提MASCON方法解算思路的可靠性,该方法为研究局部地区的地表物质迁移提供了一种可行手段.

Research on the MASCON method for the determination of local surface mass flux with Satellite-Satellite Tracking technique

The MASCON (Mass Concentration) method is an effective technique to study the mass flux of the shallow earth surface by using the GRACE satellite-satellite tracking (SST) technique directly. Compared with the Stokes spherical harmonic coefficient method, it can overcome the uncertainty problem of the filtering of time variable signals and effectively solve the problem of the North-South stripes in the solution of the GRACE earth gravity models. In this paper, the existing local MASCON method is improved, and the satellite precise orbit is introduced as the observations to solve for the parameters of MASCON and the relating dynamic models by combining the high-low SST and low-low SST measurements. To ensure the time variable signals be mainly derived from the inter-satellite range-rates, the variance component estimation method is used to determine a reasonable weight. By using the precise orbit as the absolute reference, a modified way to realize the MASCON is studied in this paper. Using the GRACE satellite gravity data in 2008, the water storage change in terms of equivalent water height (EWH) of Amazon basin is achieved. Compared with those computed from the GLDAS model, the time variable gravity models of the CSR Release 05 version and the MASCON solution by JPL, our results are confirmed to have good consistence, supporting the ideas on the method recommended in this article, which may provide a feasible way to study the local surface mass flux.