CRA-LICOM: A global high-frequency atmospheric and oceanic temporal gravity field product (2002-2024)

CRA-LICOM are the atmospheric and oceanic temporal gravity filed product, also called the de-aliasing product, that includes six-hourly Stokes coefficients (ATM, OCN, GLO, OBA), their corresponding monthly average Stokes coefficients (GAA, GAB, GAC, GAD), and the Stokes coefficients of atmospheric tides (K1, M2, P1, T2, L2, N2, S1). The ATM component represents the effects of atmospheric surface pressure over continents, the static contribution of atmospheric pressure to ocean bottom pressure elsewhere, and the relatively weaker contribution of upper-air density anomalies over both continents and oceans. The OCN component accounts for the dynamic ocean contribution to ocean bottom pressure. The sum of ATM and OCN forms the GLO coefficients. The OBA component, set to zero over continents, provides simulated ocean bottom pressure that integrates both air and water contributions in oceanic regions. The Stokes coefficients are computed from the corresponding pressure fields using spherical harmonic analysis. The atmospheric fields are sourced from CRA40 (the 40-year global reanalysis dataset released by China Meteorological Administration), while the ocean bottom pressure is simulated using LICOM (LASG/IAP Climate System Ocean Model 3.0), which is forced with CRA40. Atmospheric tides are extracted using tidal harmonic analysis methods. The de-aliasing product has a maximum degree of 180, corresponding to a spatial resolution of approximately 50 km. The current temporal coverage for six-hourly and montly average Stokes coefficients spans from January 2002 to April 2024, with plans for continuous updates. The atmospheric tide are calculated form 2007-2014. CRA-LICOM effectively captures Earth's high-frequency mass variations with sufficient accuracy to fulfill the de-aliasing requirements of modern satellite gravimetry missions. CRA-LICOM has proven effective in temporal gravity recovery from GRACE, producing results comparable to the latest official products from CSR, JPL, and GFZ. Additionally, as an independent dataset, CRA-LICOM provides a valuable resource for investigating uncertainties in high-frequency temporal gravity fields.