Water Balance Estimates From Time-Variable Satellite Gravity

GRACE卫星任务提供的地球全球重力场的月解将用于估计和解释陆地上储存的液态水和雪的垂直综合分布的逐月变化。GRACE提供的重力场球面调和系数将用于估计地球表面大陆区域的平均质量变化。这将涉及到为这些区域特别定制的平均函数的构建。这些变化将根据这些地区储水量的变化来解释。将被估计和解释的事项包括：大区域（大于20万平方公里）内储水量的变化；大流域降水减去蒸发平均值；北纬地区积雪量变化；以及地下蓄水层面积大的地区总储水量的变化。这项工作将成为一名研究生的博士论文项目，将是将时变卫星重力观测整合到水文科学的第一步。这些观测结果构成了一种新的和创新的水文学数据类型，对改善对全球水循环的理解具有很大的希望。

0309678WahrMonthly solutions for the Earth's global gravity field,as provided bythe GRACE satellite mission, will be used to estimate and interpretmonth-to-month changes in the vertically-integrated distribution ofliquid water and snow stored on land.The spherical harmonic coefficients of the gravityfield provided by GRACE will beused to estimate mass variations averaged over continental regionson the Earth's surface.This will involve the construction ofaveraging functions that are specially tailoredfor those regions.These variations will be interpreted interms of changes in the mass of water stored in those regions.Among the things that will be estimated and interpreted are:changes in the total amount of water stored within large regions (greaterthan 200,000 square km);precipitation minus evaporation averagedover large river basins;changes in snowpack at northern latitudes; andchanges in the total water stored in regions withlarge underground aquifers.This work, which will form the PhD thesisproject of a graduate student,will be a first step towards integrating time-variablesatellite gravity observations into the hydrological sciences.These observations constitute a new and innovative data type for hydrology,with considerable promise for improved understandingof the global water cycle.