Interannual variations in degree-2 Earth's gravity coefficients C 2,0, C2,2, and S2,2 reveal large-scale mass transfers of climatic origin

Abstract

Several recent studies have shown evidences for large water transfers in the climate system at interannual to decadal time scales, in particular during El Niño-Southern Oscillation events. In this study, we investigate further these water transfers and their signature in the gravity field. We analyze variations of the low-degree spherical harmonics C2,0 (Earth's oblateness), C2,2, and S2,2 (eccentricity at the Earth's equator) from satellite laser ranging data during the 19 year period 1993-2012. We also estimate the water mass transfers in the climate system using satellite altimetry corrected for the steric effect, atmospheric reanalysis, and land hydrology models. We find a large signal in the water mass redistribution during the 1997/1998 El Niño which is consistent with an increase of the ocean mass in the tropical Pacific, a decrease of water storage in the Amazon Basin, and an increase of water storage in the Congo Basin. © 2013. American Geophysical Union. All Rights Reserved.