Penetration of Atlantic westerly winds into Central and East Asia

Abstract

The geographical position of the convergence zone where the western Atlantic climate system meets the Asian (winter) monsoonal system depends on their relative strength. These individual strengths are determined by the intensities of the air pressure gradients over the North Atlantic, and the Siberian High Pressure Cell, respectively. Since the factors that forced those gradients varied throughout glacial–interglacial cycles, the location of the convergence zone should have moved accordingly. Both the grain-size characteristics of wind blown sediments and climate modelling prove that the Atlantic influence extended remarkably far eastward at times. The northeastern Tibetan Plateau was at the cross-road of western and monsoonal influences. During the last glacial this region was dominated by an Atlantic signal with millennial-scale climatic oscillations that are similar to the North Atlantic marine and Greenland ice-core records. In contrast, that same region was only under monsoonal influence during the last interglacial. It implies that the Atlantic winds penetrated more vigorously eastward in full glacial conditions than in interglacial conditions.