Contributions of hydrological processes to sea level change

Abstract

We estimate the global mean sea level (GMSL) change using TOPEX/Poseidon satellite radar altimeter measurements and investigate possible contributions from water mass redistribution within the global hydrological cycle using a few numerical models. We examine the global mean sea level change at seasonal, interannual, and long-term time scales. The atmospheric and hydrological models include the ECMWF operational atmospheric model and the NCEP/NCAR reanalysis system. The World Ocean Atlas 1998 and over 19 years’ satellite sea surface temperature observations are used to evaluate steric mean sea level change at different time scales. Both hydrological cycle and steric change provide important contribution to seasonal GMSL change. At interannual time scales, atmospheric water vapor variation shows good correlation to the altimeter observation and can introduce observable changes in the mean sea level. The snow water over Greenland and Antarctica estimated from the ECMWF model also shows encouraging interannual variability during the 1997/1998 El Niño period. Preliminary results show that thermal effect is a major but not a dominant contributor to long-term sea level rise, indicating that snow and ice melting associated with global warming may play an important role in driving GMSL rise.