Arctic Ocean, North and Baltic Sea GHRSST-compliant SST and IST products for the Copernicus Marine Service

Satellite missions carrying Thermal Infrared (TIR) and Passive Microwave Sensors (PMW) allow for high-resolution Sea Surface Temperature (SST) and Sea-Ice Surface Temperature (IST) retrievals under clear skies (TIR) and all weather retrievals (PMW) albeit with coarser resolution. This allows the continuous provision of SST and IST to operational Numerical Weather Prediction systems, climate models and to the wider scientific community. DMI is a Production Unit (PU) for the Sea Ice (SI) and SST Thematic Assembly Centers (TAC) of the Copernicus Marine Monitoring Service (CMS) providing a suite of level 4 SST products for the Arctic Ocean, the Baltic and North Sea daily, hourly and as multi-year products.

The L4 Near-Real-Time (NRT) SST product SST-BAL-SST-L4-NRT-OBSERVATIONS-010-007-b is a daily, multi-sensor, gap-free, optimally interpolated product derived from night-time SST retrievals at high resolution (0.02^o), available from 2016 onward. The L4 Multi-Year SST product SST-BAL-SST-L4-REP-OBSERVATIONS-010-016 is a daily, multi-sensor, level 4 optimally interpolated product using infra-red satellite observations from the ESA CCI and Copernicus C3S projects and high resolution sea ice information from SMHI and the SI TAC available from 1982 to 2022. The L4 Near-Real-Time Diurnal SST product SST-BAL-PHY-SUBSKIN-L4-NRT-010-034 is an hourly, gap-free satellite sub-skin SST analysis using L2P and L3 single-sensor SST data as input.

For the Arctic Ocean, the L4 NRT SST/IST product ARC-SEAICE-L4-NRT-011-008 is a daily, multi-sensor, gap-free and optimally interpolated analysis of sea surface and sea-ice surface temperatures at a resolution of 0.05^o extending north of 58 ^oN and available from 2018 onwards. The corresponding MY product, ARC-SEAICE-L4-NRT-011-016, is the first combined SST and IST analysis of the Arctic available from 1982 and up to 2023.

Within the current C3S portfolio, DMI will provide the SST ECV, i.e. a global (up to 90^o latitude), sub-skin product (20 cm) with a 0.05^o spatial resolution. The aim of the present study is to provide an overview of the available products and their performance along with insights on future developments and products.