Influence of the 26°N RAPID–MOCHA Array and Florida Current Cable Observations on the ECCO–GODAE State Estimate

Abstract

The incorporation of local temperature and salinity observations from the Rapid Climate Change?Meridional Overturning Circulation and Heatflux Array (RAPID?MOCHA), as well as the cable estimates of volume transport in the Florida Current (FC), is tested in the Estimating the Circulation and Climate of the Ocean?Global Ocean Data Assimilation Experiment (ECCO?GODAE) estimation system for their impact on the estimate of the meridional overturning circulation (MOC) and the meridional heat transport in the Atlantic. An experimental setup covering the first deployment period of RAPID?MOCHA from March 2004 to March 2005 is used to test different strategies for incorporating these datasets. Incorporating both monthly means of the FC data and monthly means of the RAPID?MOCHA temperature and salinity measurements at the eastern and western boundaries of the basin as an observational constraint in a 1-yr experiment results in an adjustment to the reference estimate, which does not include these datasets, of approximately 1 Sv (1 Sv ≡ 106 m3 s?1) in the MOC at 26°N and the adjacent latitudes (approximately ±15°), with a larger northward branch of the MOC above 1000 m, compensated by a larger flow in the southward branch of the MOC between approximately 2000 and 3000 m. The meridional heat transport from 26°N to near 40°N is approximately 0.05 PW larger than in the reference experiment.