Open AccessThe Effect of Southern Ocean Surface Buoyancy Loss on the Deep-Ocean Circulation and Stratification
Author(s) -
Malte F. Jansen,
Louis-Philippe Nadeau
Publication year - 2016
Publication title -
journal of physical oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 143
eISSN - 1520-0485
pISSN - 0022-3670
DOI - 10.1175/jpo-d-16-0084.1
Subject(s) - abyssal zone , buoyancy , stratification (seeds) , oceanography , geology , ocean current , shutdown of thermohaline circulation , north atlantic deep water , antarctic bottom water , thermohaline circulation , seabed , deep sea , climatology , mechanics , seed dormancy , physics , germination , botany , dormancy , biology
The deep-ocean circulation and stratification have likely undergone major changes during past climates, which may have played an important role in the modulation of atmospheric CO 2 concentrations. The mechanisms by which the deep-ocean circulation changed, however, are still poorly understood and represent a major challenge to the understanding of past and future climates. This study highlights the importance of the integrated buoyancy loss rate around Antarctica in modulating the abyssal circulation and stratification. Theoretical arguments and idealized numerical simulations suggest that enhanced buoyancy loss around Antarctica leads to a strong increase in the abyssal stratification, consistent with proxy observations for the last glacial maximum. Enhanced buoyancy loss moreover leads to a contraction of the middepth overturning cell and thus upward shift of North Atlantic Deep Water (NADW). The abyssal overturning cell initially expands to fill the void. However, if the buoyancy loss rate further increases, the abyssal cell also contracts, leaving a “dead zone” with vanishing meridional flow at middepth.