An Observation‐Based Estimate of Atlantic Meridional Freshwater Transport

Abstract

Abstract Meridional freshwater transport (MFT) in the Atlantic Ocean (Atlantic meridional freshwater transport (AMFT)) plays a vital role in the Atlantic Ocean circulations, but an accurate estimate of AMFT time series remains challenging. This study uses an indirect approach that combines ocean salinity, surface evaporation and precipitation observations to derive AMFT and its uncertainty by solving the ocean freshwater budget equation. Climatologically, AMFT is southward between 18.5°S and 34.5°S, but northward from 18.5°S to 66.5°N. AMFT also shows substantial inter‐annual variability with a clear separation at ∼40°N and is more coincident with the Atlantic Meridional Overturning Circulation (AMOC) at 26°N than 47°N across latitudes. The derived time series indicates that throughout the Atlantic Ocean, there is a positive trend in the AMFT from 2004 to 2020, resulting in an AMFT convergence in the tropical Atlantic and an AMFT divergence in the subtropical North Atlantic.

Keywords

• Atlantic meridional freshwater transport
• meridional coherence
• ocean freshwater budget
• ocean salinity