Loomis B D, Luthcke S B, Sabaka T J
NASA Goddard Space Flight Center, Geodesy and Geophysics Laboratory, Greenbelt, MD, USA.
NASA Goddard Space Flight Center, Greenbelt, MD, USA.
J Geod. 2019 Sep;93(9):1381-1398. doi: 10.1007/s00190-019-01252-y. Epub 2018 Apr 15.
We present a new global time-variable gravity mascon solution derived from Gravity Recovery and Climate Experiment (GRACE) Level 1B data. The new product from the NASA Goddard Space Flight Center (GSFC) results from a novel approach that combines an iterative solution strategy with geographical binning of inter-satellite range-acceleration residuals in the construction of time-dependent regularization matrices applied in the inversion of mascon parameters. This estimation strategy is intentionally conservative as it seeks to maximize the role of the GRACE measurements on the final solution while minimizing the influence of the regularization design process. We fully reprocess the Level 1B data in the presence of the final mascon solution to generate true post-fit inter-satellite residuals, which are utilized to confirm solution convergence and to validate the mascon noise uncertainties. We also present the mathematical case that regularized mascon solutions are biased, and that this bias, or leakage, must be combined with the estimated noise variance to accurately assess total mascon uncertainties. The estimated leakage errors are determined from the monthly resolution operators. We present a simple approach to compute the total uncertainty for both individual mascon and regional analysis of the GSFC mascon product, and validate the results with comparisons to independent mascon solutions and calibrated Stokes uncertainties. Lastly, we present the new solution and uncertainties with global analyses of the mass trends and annual amplitudes, and compute updated trends for the global ocean, and the respective contributions of the Greenland Ice Sheet, Antarctic Ice Sheet, Gulf of Alaska, and terrestrial water storage. This analysis highlights the successful closure of the global mean sea level budget; i.e. the sum of global ocean mass from the GSFC mascons and the steric component from Argo floats agrees well with the total determined from sea surface altimetry.
我们展示了一种从重力恢复与气候实验（GRACE）1B级数据中得出的全新全球时变重力质心解。美国国家航空航天局戈达德太空飞行中心（GSFC）的这一新产品源于一种新颖的方法，该方法在构建用于质心参数反演的时间相关正则化矩阵时，将迭代求解策略与卫星间距离加速度残差的地理分箱相结合。这种估计策略有意保持保守，因为它试图在最终解中最大化GRACE测量的作用，同时最小化正则化设计过程的影响。我们在存在最终质心解的情况下对1B级数据进行完全重新处理，以生成真正的拟合后卫星间残差，这些残差用于确认解的收敛性并验证质心噪声不确定性。我们还给出了数学案例，即正则化质心解存在偏差，并且这种偏差或泄漏必须与估计的噪声方差相结合，以准确评估质心的总不确定性。估计的泄漏误差由月度分辨率算子确定。我们提出了一种简单的方法来计算GSFC质心产品的单个质心和区域分析的总不确定性，并通过与独立质心解和校准的斯托克斯不确定性进行比较来验证结果。最后，我们通过对质量趋势和年振幅的全球分析展示新的解和不确定性，并计算全球海洋的更新趋势，以及格陵兰冰盖、南极冰盖、阿拉斯加湾和陆地水储量的各自贡献。该分析突出了全球平均海平面预算的成功闭合；即GSFC质心中的全球海洋质量与Argo浮标中的比容分量之和与从海面测高确定的总量非常吻合。
