JRA55 reanalysis is an auxiliary data set for SMOS sea ice thickness retrieval. The update of this near real-time JRA55 data will terminate at the end of January 2024, instead, the Japanese Reanalysis for Three Quarters of a Century (JRA-3Q) will be used thereafter. The impact of this transition on L3 SMOS and L4 CS2SMOS products will be analyzed in detail after the reprocessing of the complete data in April 2024. A preliminary comparison of JRA55 and JRA-3Q temperature and its impact on L3 SMOS sea ice thickness product is shown in Figure 1. There is temperature difference up to 5K in some regions in the Arctic, which is caused by the update of sea-ice and snow schemes in JRA-3Q. 

Figure 1. Temperature difference between JRA-3Q and JRA55 in December 2023 (left) and the difference in SMOS sea ice thickness caused by the transition from JRA55 to JRA-3Q for the same month (right).