The M2 oceanic tide recovered from Seasat altimetry in the Indian Ocean

Abstract

Seasat altimeter data, which provide measurements of the instantaneous ocean level, are used here to create a model of the M2 oceanic tide in the Indian Ocean. This approach avoids the assumptions introduced in the hydrodynamical tide models and takes advantage of a regular distribution of the data over the whole ocean. The hydrodynamical and empirical models that have been proposed for this ocean1–11 exhibit strong discrepancies, particularly in the deep ocean so that the use of altimeter data is of particular interest. Attempts to recover the tides in limited areas of the Atlantic and Pacific oceans from altimeter data have been made previously12–17. We investigate a new method to obtain the amplitude and phase of M2 in a large region. The validity of the model is checked using synthetic data and by comparison with tide gauge data, and seems to be reliable in the deep ocean.