A Region of Enhanced Northward Antarctic Intermediate Water Transport in a Coupled Climate Model

Abstract

Abstract A global coupled model is used to examine pathways of freshwater transport in the Southern Ocean. On the background of a strong zonal freshwater transport along the pathway of the Antarctic Circumpolar Current (ACC), there are meridional freshwater flows distributed nonuniformly around the globe, including in the upper ocean. The analysis does not support a simple two-dimensional scheme of Antarctic Intermediate Water (AAIW) formation, according to which the fresh AAIW forms uniformly around the circumpolar ocean. Rather, a more complex three-dimensional picture of the freshwater transport in the Southern Ocean is revealed, with enhanced AAIW formation in the southeast Pacific Ocean both north and south of the Drake Passage latitudes. Freshened by intense precipitation and surface waters from around Antarctica, the ACC transports freshwater from the northwest to the southeast toward Drake Passage. There, a fraction of this freshwater is transported southward across 60°S with the subsurface ACC an...