Annual cycle in mean sea level from Topex-Poseidon and ERS-1: inference onthe global hydrological cycle

Using satellite altimetry time series from Topex-Poseidon and ERS-1 to esti mate the annual variation of the global mean sea level, we study the global hydrological cycle at the annual frequency. The observed annual sea level signal is first corrected for steric effects and further compared to the an nual change in atmospheric water vapor content and soil moisture of contine nts. The altimetry-derived global mean sea level variation corrected for st eric effects, i.e., due to annual ocean mass change amounts to 9.5 mm with a maximum in mid-September. This observation is consistent with the signal estimated from atmospheric and continental data. Accounting for the variati ons of water mass stored in the superficial soil layers and in the atmosphe re, one can get a reasonable phase agreement with satellite observations, w ith an amplitude difference of only 2.5 mm. This difference may result from uncertainties of the soil moisture estimate, or from neglecting the water storage variations in other reservoirs, such as the rivers, the underground or the ice sheets. (C) 1999 Elsevier Science B.V. All rights reserved.