Atmospheric and oceanic freshwater transport during weak Atlantic overturning circulation

Abstract

Oceanic and atmospheric freshwater transports are analyzed in a numerical experiment where inducedfreshwater in the North Atlantic slowed the thermohaline circulation (THC). During times of weakAtlantic overturning circulation, it is found that the Intertropical Convergence Zone moves southwardand trade winds at tropical latitudes increase, resulting in enhanced water vapor export out of theAtlantic catchment area. The experiment reveals furthermore that the oceanic freshwater transportamounts to a stabilizing effect of similar magnitude to the atmospheric effect. It is argued that themodeled response can be used as a fingerprint for the detection of THC changes documented in thepaleoclimatic record or related recent climate change.