Contrasting patterns of Last-deglacial and Holocene precipitation between the southern and northern portions of the Arid Central Asia

ABSTRACT

The north-south migration of prevailing westerly system strongly shapes the seasonality of modern precipitation in Arid Central Asia (ACA). The temperate continental climate with warm-season precipitation dominates the northern ACA and the Mediterranean climate with cold-season precipitation dominates the southern ACA. However, the north-south contrasts of precipitation/moisture for longer time scales remain unknown. In this study, we quantitatively reconstructed the precipitation sequence covering the past ~14.4 cal. kyrs based on pollen data obtained from Shayan loess section in the southern ACA using MAT (Modern Analogue Technique) method. Ours reconstruction shows that the precipitation had an increasing trend from ~14.4 to ~8.2 cal. kyr BP and a decreasing trend from ~8.2 to ~1.5 cal. kyr BP with the past 1500 years being characterized by an averagely high precipitation. The precipitation trend in the southern ACA was rather different from that in the northern ACA. That is, the precipitation has increased more or less constantly since the late deglaciation in the southern ACA. The contrast between the southern ACA and the northern ACA appears to have been associated with the south-north migration of westerlies that was accompanied with alterations of NAO (North Atlantic Oscillation) phases and also with changes in strengths of Siberian High and ENSO (El Nino-southern Oscillation).