Global and regional sea level change from multi-satellite altimeter data
Remko Scharroo(1) , Laury Miller(2) , Andy Ridout(3) , and Seymour Laxon(3)
330a Parsonage Road,
Cornish, NH 03745,
(2) NOAA/NESDIS, 1335 East-west Highway, Silver Spring, MD 20910, United States
(3) University College London, Gower Street, London WC1E 6BT, United Kingdom
A record of fifteen years of precision altimeter data has been built up, including the data of ERS-1, TOPEX, ERS-2, GFO, Jason-1 and Envisat, each with their different strengths and weaknesses. Only by careful analysis and correction of drifts and biases in the altimeter and microwave radiometer data we can combine them efficiently to create an accurate record of sea level change both globally and regionally.
This presentation discusses some of the difficulties faced in the combination of such diverse altimeter records, including the importance of fixing long-term instrumental drifts, the existence of temporal and regional variations in sea level trend.
The combination of the data of all six altimeters is essential to the building of an accurate long-term record. Without comparison errors and drifts can remain unnoticed, and different observed regional trends stimulate and aid the analysis of the measurements and their numerous corrections. Some further emphasis is put on the trend in the Arctic region, measured by ERS and Envisat, but beyond the reach of TOPEX and Jason-1.
The altimeter data has also been compared to tide gauge data and estimates for sea level rise based on budgets for melting of ice shelves, increase runoff, thermal expansion, etc.