LDCmgm90 monthly geopotential model set with separate GIA model

This is an updated version of LDCmgm90, which has assimilated CSR RL06 mascon and GSFC SLR degree-2 Stokes coefficients besides all the data sets used in the previous version (see https://www.nature.com/articles/s41597-019-0239-7 for more details).In addition, The ICE-6G_C used for RL05 mascons, and ICE-6G_D used for RL06 mascons are added back because there are still somewhat large uncertainties in GIA modeling. Instead, we provide a corrected GIA model ICE6Gavg(GPS) as a separate data set (see the attached pdf for more details about this GIA model).While the GRACE (Gravity Recovery and Climate Experiment) satellite mission is of great significance in understanding various branches of Earth sciences, the quality of GRACE monthly products can be unsatisfactory due to strong longitudinal stripe-pattern errors and other flaws. Based on corrected GRACE Mascon (mass concentration) gridded mass transport time series and updated LDCgam (Least Differential Combination global angular momenta) data, we present a new set of monthly gravity models called LDCmgm90, in the form of Stokes coefficients with order and degree both up to 90. The LDCgam inputs are developed by assimilating degree-2 Stokes coefficients from various versions of GRACE (including Mascon products) and SLR (Satellite Laser Ranging) monthly gravity data into combinations of outputs from various global atmospheric, oceanic, and hydrological circulation models, under the constraints of accurately measured Earth orientation parameters in the Least Differential Combination (LDC) scheme. Taking advantages of the relative strengths of the various input solutions, the LDCmgm90 is free of stripes and some other flaws of classical GRACE products.

本数据集为LDCmgm90的更新版本，除沿用前版所用的全部数据集外，还同化了CSR RL06质量浓度（mascon）与GSFC SLR的二阶斯托克斯（Stokes）系数，详细说明见https://www.nature.com/articles/s41597-019-0239-7。此外，考虑到冰川均衡调整（GIA，Glacial Isostatic Adjustment）建模仍存在较大不确定性，本次更新恢复使用了RL05质量浓度所用的ICE-6G_C模型与RL06质量浓度所用的ICE-6G_D模型，并额外提供经校正的GIA模型ICE6Gavg(GPS)作为独立数据集，该GIA模型的详细说明见附件PDF。尽管重力恢复与气候实验（GRACE，Gravity Recovery and Climate Experiment）卫星任务对地球科学诸多分支的研究具有重要意义，但受较强的纵向条带误差及其他缺陷影响，GRACE月度产品的质量往往不尽如人意。本数据集基于校正后的GRACE质量浓度（mascon）网格质量传输时间序列与更新后的LDCgam（最小差分组合全球角动量）数据，构建了一套新的月度重力场模型LDCmgm90，其斯托克斯系数的阶与次均最高可达90。LDCgam输入数据的构建方式为：在精确测量的地球定向参数约束下，采用最小差分组合（LDC，Least Differential Combination）方案，将多版本GRACE（含质量浓度产品）与SLR（卫星激光测距，Satellite Laser Ranging）的月度重力场数据的二阶斯托克斯系数，同化至多套全球大气、海洋与水文环流模型的输出组合中。该模型依托各类输入解的相对优势，消除了经典GRACE产品常见的条带误差及其他部分缺陷。