An improved Antarctic sea-ice snow depth product from FY-3 MWRI with enhanced seasonal adaptability

Accurate estimation of snow depth on Antarctic sea ice is critical for understanding ice mass balance, surface thermodynamics, and satellite-altimetry-based sea ice thickness retrievals. This study introduces a dual-mode retrieval framework for deriving a snow depth product on Antarctic sea ice using the Microwave Radiation Imager (MWRI). The MWRI snow depth product outperforms existing passive-microwave products in accuracy, seasonal adaptability, and temporal consistency. Validation against multiple in situ datasets shows that MWRI snow depth achieves superior performance across most Antarctic regions, notably with an RMSE below 9.0 cm and a correlation coefficient above 0.70 in West Antarctica. During the melt season, validation with AWI snow buoys yielded an RMSE of 8.5 cm, demonstrating robustness under complex surface conditions. Time-series comparisons with ICESat-2 snow depth demonstrate that the MWRI snow depth effectively captures seasonal variability (r = 0.79), accurately reproducing the winter-to-spring snow-accumulation trend. Seasonally, snow depth rises in winter and early spring and diminishes during summer melt and compaction. Interannually, long-term snow-covered zones—particularly the Weddell and Amundsen Seas—remain relatively stable and thick, while marginal ice areas exhibit a clear thinning trend. The dataset is available at https://doi.org/10.57760/sciencedb.25039.