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

B. Meyssignac (1) , J. M. Lemoine (2) , Gm. Chen (3) , A. Cazenave (1) , P. Gegout (2) , Philippe Maisongrande (1)

1 GOHS
2 GET - Géosciences Environnement Toulouse
3 CSR

Several recent studies have shown evidences for large water transfers in the climate system at interannual to decadal time scales, in particular during El Nino-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 C-2,C-0 (Earth's oblateness), C-2,C-2, and S-2,S-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 Nino 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.

Mots clés: time-variable gravity field; gravity coefficients C20C22S22; ENSO; climatic mass transfers; WATER; REDISTRIBUTION; VARIABILITY; OBLATENESS; MODEL

Domaines: Océan, Atmosphère

B. Meyssignac, J. M. Lemoine, Gm. Chen, A. Cazenave, P. Gegout, et al.. Interannual variations in degree-2 Earth's gravity coefficients C-2,C-0, C-2,C-2, and S-2,S-2 reveal large-scale mass transfers of climatic origin. Geophysical Research Letters, 2013, 40 (15), pp.4060-4065. ⟨10.1002/grl.50772⟩. ⟨hal-00991277⟩