Correlation of interannual sea level variations in the Indian Ocean from Topex/Poseidon altimetry, temperature data and tide gauges with ENSO

Abstract

Indian Ocean sea level observed by Topex/Poseidon (T/P) altimetry during 1993-1999, steric sea level for 1957-1998 based on recently released global ocean temperature data, and long tide gauge record (over the past century) along the Indian coast are analysed to investigate the dominant mode of interannual change and its (possible) correlation with El Nino-Southern Oscillation (ENSO). We first focus on recent years where dense sea level coverage is provided by satellite altimetry and extend the result with an analysis of the steric sea level to the past 40 years and look for any correlation with the Southern Oscillation Index (SOI). Finally, we present result of sea level fluctuations based on long tide gauge record on the Indian coast. Our results suggest significant correlation of sea level changes in the Indian Ocean with ENSO events suggesting external forcing for interannual sea level variations in the Indian Ocean. However, there are time spans during which the correlation is poor or non-existent that might be caused due to internal dynamics of Indian Ocean. Thus, it appears that there is some competition between internal dynamics forcing and external influence by ENSO phenomena on interannual sea level variations in the Indian Ocean