Research Spotlight: Using satellite data to estimate the North Atlantic Ocean circulation

Abstract

By redistributing heat and freshwater around the planet, ocean currents play a crucial role in regulating Earth's climate. Accurate knowledge of the subtle regional variations in Earth's gravity field is fundamental to the measurement of ocean currents, but the challenge of mapping Earth's gravity in sufficient detail has previously limited scientists' ability to reliably determine the ocean's time‐mean circulation. To address this problem, in October 2009 the European Space Agency launched the Gravity field and steady‐state Ocean Circulation Explorer (GOCE) satellite with the aim of mapping Earth's gravity field with unprecedented spatial resolution. Bingham et al. present an initial assessment of the performance of GOCE by using the first data from the satellite to estimate the time‐mean circulation of the North Atlantic Ocean. This basin is particularly interesting because it contains the Gulf Stream, the world's strongest current and a key component of the global overturning circulation, which carries heat from the equator to high northerly latitudes. The scientists show that with just 2 months of observations, the GOCE estimate of the North Atlantic circulation is superior to that obtained from 8 years of data from the Gravity Recovery and Climate Experiment (GRACE) satellite. In many places, the current speeds estimated from the GOCE data compare well with those obtained from in situ observations, providing strong validation of the GOCE mission design. Accumulation of data as the mission progresses could lead to a more accurate and detailed map of the ocean's currents. (Geophysical Research Letters, doi:10.1029/2010GL045633, 2011)