LOCEAN and ACRI-ST have derived improved level 3 (L3) SMOS Sea Surface Salinity (SSS) maps over the Arctic Ocean. With respect to SMOS ARCTIC SSS L3 V1.0, main changes in version 2.0 are as follows:

• 9-day and 18-day maps are provided over the June 2010 to August 2023 period,
• the methodology originally derived by Supply et al. 2020 and implemented in SMOS ARCTIC SSS V1 maps has been revisited,
• a temporal optimal interpolation with a bias removal depending on the SMOS observation geometry (see a general description in Boutin et al., 2018) has been added,
• comparisons with independent in situ datasets, conducted in CEC LOCEAN and in PIMEP, indicate a clear improvement (reduction of std difference by ~a factor 2 and systematic increase of r²); with V2.0 r² is greater than 0.8 with 40% of the data sets considered at PIMEP (see more details on CATDS webpage https://www.catds.fr/Products/Products-over-Ocean/CEC-Locean-L3-Arctic-V2).

As in version 1, SSS maps are provided on an Equal-Scalable Earth Grid 2 (EASE, https://nsidc.org/data/ease) with a Northern Hemisphere Azimuthal projection and a resolution of 25km.

LOCEAN and ACRI-st work as Ocean Salinity Center of Expertise for CATDS (CATDS CEC-OS) in order to improve methodologies to be implemented in the future in the near real time CATDS processing chain (CATDS-CPDC). Feedbacks from users about the quality of these new products are very welcome, as they are experimental.