Improved satellite altimetry for the observation of coastal ocean dynamics: a case study for the Northern Indian Ocean

摘要

The coastal currents in the Northern Indian Ocean are believed to play a prominent role in the heat and salt exchanges between Arabian Sea and Bay of Bengal. Hence it appears timely to carefully monitor their structure and variability at all timescales from intraseasonal to interannual. The objective of this study is to determine to what extent the sea surface height (SSH) variability associated to these coastal processes can be observed with satellite altimetry, in the Northern Indian ocean sector. Indeed, radar altimetry, which allows to measure SSH at centimetric accuracy, has been shown to be a powerful tool to obtain a wealth of information about open-ocean dynamics. Unfortunately, today, the use of standard satellite altimetric products in coastal zones remains challenging. This study explores a newly released coastal altimetric dataset, obtained from a complete reprocessing of the Topex/Poseidon data. We first present an objective method to derive geostrophic current from the raw SSH. Then we present the validation of the altimetric SSH against in situ observations. Finally we briefly analyze the observed variability of the East India Coastal Current at various timescales.