CRA-LICOM: 全球高频大气海洋时变重力场产品（2002-2024）

CRA-LICOM 是大气海洋时变重力场产品，也叫大气海洋去混频产品，它包含逐六小时Stokes系数（ATM、OCN、GLO、OBA），其对应的月平均Stokes系数（GAA、GAB、GAC、GAD），以及大气潮汐（K1、M2、P1、T2、L2、N2、S1）的Stokes系数。

ATM 表示大气压在陆地上的贡献、大气压力对海底压力的静态贡献，以及大陆和海洋上空较弱的高空气体密度异常的贡献。OCN 反映了动态海洋对海底压力的贡献。ATM 和 OCN 的总和形成了 GLO 系数。而 OBA 在大陆上为零，在海洋区域提供气柱和水柱共同作用造成的海底压力。

Stokes系数通过球谐分析从相应的压力场计算得出。其中，大气场由 CRA40（the 40-year global reanalysis dataset released by China Meteorological Administration）提供，海底压力由在 CRA40 强迫下运行的 LICOM（LASG/IAP Climate System Ocean Model 3.0）模拟。此外，大气潮汐通过潮汐谐波分析方法提取。

该去混叠产品的最大阶数为 180，对应约 50 公里的空间分辨率。目前逐6h和月平均球谐系数的时间覆盖范围为 2002 年 1 月至 2024 年 4 月，并计划持续更新。大气潮汐的时间范围是2007-2014年。CRA-LICOM 能够有效捕捉地球的高频质量变化，其精度足以满足现代卫星重力测量任务的去混叠需求。

CRA-LICOM 在基于 GRACE 的时变重力场重建中效果显著，其结果与 CSR、JPL 和 GFZ 提供的最新官方产品相当。此外，作为一个独立的数据集，CRA-LICOM 为研究高频时间重力场的不确定性提供了宝贵的资源。

CRA-LICOM is an atmospheric and oceanic time-variable gravity field product, also known as the atmospheric-oceanic de-aliasing product. It includes 6-hourly Stokes coefficients (ATM, OCN, GLO, OBA), their corresponding monthly-averaged Stokes coefficients (GAA, GAB, GAC, GAD), as well as Stokes coefficients for atmospheric tides (K1, M2, P1, T2, L2, N2, S1).

ATM represents the contributions of atmospheric pressure over land, the static contribution of atmospheric pressure to seafloor pressure, and the contributions of weak upper-atmospheric gas density anomalies over continents and oceans. OCN reflects the contribution of dynamic ocean to seafloor pressure. The sum of ATM and OCN forms the GLO coefficients. OBA is zero over continents, and provides seafloor pressure caused by the combined effect of air column and water column in oceanic regions.

Stokes coefficients are calculated from the corresponding pressure fields via spherical harmonic analysis. The atmospheric field is provided by CRA40 (the 40-year global reanalysis dataset released by the China Meteorological Administration), and seafloor pressure is simulated by LICOM (LASG/IAP Climate System Ocean Model 3.0) forced by CRA40. In addition, atmospheric tides are extracted via tidal harmonic analysis.

The maximum degree of this de-aliasing product is 180, corresponding to a spatial resolution of approximately 50 km. Currently, the temporal coverage of 6-hourly and monthly-averaged spherical harmonic coefficients ranges from January 2002 to April 2024, with plans for continuous updates. The temporal range of atmospheric tides is 2007–2014. CRA-LICOM can effectively capture high-frequency mass variations of the Earth, and its accuracy meets the de-aliasing requirements of modern satellite gravity measurement missions.

CRA-LICOM performs excellently in GRACE-based time-variable gravity field reconstruction, and its results are comparable to the latest official products provided by CSR, JPL and GFZ. Furthermore, as an independent dataset, CRA-LICOM provides a valuable resource for studying the uncertainty of high-frequency temporal gravity fields.

搜集汇总

背景与挑战

背景概述

CRA-LICOM数据集提供2002-2024年全球高频大气海洋时变重力场数据，包含逐六小时和月平均Stokes系数及大气潮汐数据，空间分辨率0.5°-1°，适用于卫星重力测量任务的高频质量变化研究。