Ekman transport and upwelling during Younger Dryas estimated from wind stress from GENESIS climate model experiments with variable North Atlantic heat convergence

Abstract

Reconstructed climatic changes during the Younger Dryas interval are similar to, but somewhat larger and more wide-spread than, those expected based on the direct atmospheric effects of reduced North Atlantic oceanic heat transport. The paleoclimatic data show that North Atlantic cooling during the Younger Dryas was accompanied by stronger winds in many regions, suggesting that enhanced wind-driven ocean upwelling may have served as a positive feedback on the cooling. We test this hypothesis using the GENESIS atmospheric general circulation model, and find that Younger Dryas-age specified reduction in North Atlantic oceanic heat transport increases tropical Ekman divergence by ≈10% in regions and at times of prominent upwelling, sufficient to affect tropical temperatures. Copyright 1999 by the American Geophysical Union.