Characteristic precipitation patterns of El Niño/La Niña in time-variable gravity fields by GRACE

El Niño and La Niña are known to bring about characteristic patterns of anomalous precipitation in various regions of the world. We extracted temporary and regional gravity changes from monthly gravity fields recovered by the GRACE satellites, and converted them to the changes in surface mass, possibly ground or subsurface water in land area. Such mass changes in the 2006–2007 El Niño and 2005–2006 La Niña episodes agreed well with precipitation anomaly patterns inferred from meteorological records in tens of past such episodes. We further compared them with anomalies of soil moisture numerically simulated by integrating monthly precipitation and evapotranspiration. They agree quantitatively with the GRACE data, suggesting that temporal changes in terrestrial water storage in low-latitude region are largely governed by precipitation. This study demonstrates the potential of satellite gravimetry as a sensor of inter-annual climate changes.