Global satellite-based sea and sea-ice surface temperatures since 1982

Area of Science:

• Climate Science
• Oceanography
• Cryosphere Science

Background:

• Accurate long-term sea and sea-ice surface temperature data are crucial for understanding global climate dynamics and polar region changes.
• Existing datasets may have limitations in consistency, spatial coverage, or integration of sea-ice influence.

Purpose of the Study:

• To produce a comprehensive 43-year Climate Data Record (CDR) of global sea and sea-ice surface temperature (SST/IST) from 1982 to 2024.
• To provide a gap-free, high-resolution dataset for climate change assessment and extreme event analysis.
• To enable independent analysis of SST/IST regardless of sea-ice cover.

Main Methods:

• Integration of infrared and microwave satellite observations using optimal interpolation for daily, gap-free global SST/IST fields (0.05° resolution).
• Derivation of consistent sea-ice concentration (SIC) fields by combining passive microwave CDRs with sea ice charts.
• Inclusion of under-ice SST (UISST) data derived from SIC and monthly salinity climatologies.

Main Results:

• Validation against in situ SSTs shows excellent agreement (median differences of -0.04°C, robust std dev 0.17-0.28°C).
• Sea-ice temperature validation shows median differences from 1.41°C to -4.62°C (robust std dev 2.55-4.99°C).
• Global SST/IST increased by approximately 0.75°C from 1982-2024, with significant Arctic amplification (~4.36°C) and Antarctic warming (~0.54°C).

Conclusions:

• The new CDR offers a novel, consistent, and validated dataset for global and polar climate change research.
• The findings highlight amplified Arctic warming and recent record warmth in Antarctica, underscoring the need for continued monitoring.
• This dataset facilitates independent assessment of sea surface temperatures, crucial for understanding climate extremes.