GRACE satellite gravimetry to monitor AMOC variability and coherence in the Atlantic Ocean

Abstract:

The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism in basin-scale heat transport to high latitudes. It has significant impact in particular in the Northern Hemisphere and on Northwestern Europe’s climate. The dynamics of the AMOC especially in the North Atlantic have been observed and described in recent model and observational studies. However, in-situ observations are limited to a few latitudes where observational arrays are deployed. Also, the physical relationship between ocean bottom pressure (OBP) and the AMOC has been characterized in recent literature.

Here, we employ GRACE-derived OBP (from the JPL-RL05M mascons solution) to derive AMOC anomalies through physical relations. Viability of the approach to infer AMOC variability from GRACE-OBP observations has been demonstrated by comparing the GRACE-derived AMOC signal to in-situ observations by the RAPID array at 26.5N. In contrast to in-situ observations, GRACE observations provide the unique opportunity to derive AMOC anomalies continuously (for the GRACE time period from 2003 until present) across all latitudes of the basin, and evaluate spatial and temporal coherence.