Monitoring sea level and sea surface temperature trends from ERS satellites

Abstract

Data from the two ESA satellites ERS-1 and ERS-2 are used in global and regional analysis of sea level and sea surface temperature trends over the last 7.8 years. The ERS satellites and in the future the ENVISAT satellite provide unique opportunity for monitoring both changes in sea level and sea surface temperature as these satellites are equipped with an altimeter to measure sea level height as well as an along track scanning radiometer (ATSR) to measure the sea surface temperature. Consistent increase in both sea level and sea surface temperatures are found in most parts of the Atlantic Ocean over this period. In the Indian Ocean and particularly the Pacific Ocean the trends in both sea level and temperature are still dominated by the large changes associated with the El Ninõ Southern Oscillation. In terms of contribution to the total global sea level change, the contribution of the central Pacific Ocean is as large as the contribution of the whole North Atlantic. The regional changes detected by ERS sea level and sea surface temperature observations are highly correlated with independent finding from TOPEX/POSEIDON (T/P) sea level observations and the Reynolds advanced very high resolution radiometer (AVHRR) sea surface temperature observations. Global averaged spatial correlations between the 50° parallels are 0.87 between the ATSR and AVHRR based sea surface temperature trends values, and 0.85 between the T/P and ERS altimetric sea level trends. The spatial correlation between the ERS derived sea level change and sea surface temperature is 0.42 for both the ATSR and AVHRR derived data.