Aeolian activities change and possible mechanisms in central Asia on sub-orbital to decadal timescales

Abstract

The aeolian activity in central Asia (CA)and its relevant dust emissions significantly influenced the global climate changes and biogeochemical cycles. Fully understanding the formation processes and mechanism of aeolian activity in CA is helpful to elevate our knowledge of global climate change, materials cycles and aeolian disasters monitoring and prevention. However, this issue is still controversial at present. We systematically review and integrate the geological archives and instrumental data to trace the variations of aeolian activity on sub-orbital, centennial, and decadal timescales in CA, and assessed the relationship between aeolian activity changes and climate changes, atmospheric circulation system changes and human activities. The result suggested that on the sub-orbital scale, during the past 8500 years, the low intensity and relatively stable aeolian activity occurred during the early to middle Holocene (8500-4000 Cal. Yr B.P.), followed by a more intensive/frequent and more variable aeolian activity conditions during late Holocene (4000-0 Cal. Yr B.P.). On centennial scale, over the past 1000 years, the more intensive (attenuated)aeolian activity occurred during the Little Ice Age (Medieval Warm Period). On the decadal scale, during the last century, aeolian activity in CA has decreased greatly since the 1960s, accompanied by the increasing of temperature and precipitation. Compared to the changes of climate, atmospheric circulation system and human activities, we proposed that the Siberian High (SH) which related to the temperature variations, rather than the precipitation and human activity, largely controlled aeolian activity in CA on the sub-orbital, centennial, and decadal timescales. Cooling at high latitudes markedly enhances the intensity of the SH, which is displaced southward as a result, causing the incursion of cold air masses from high latitudes which result in more robust wind regimes that provide suitable wind regimes for dust emission the study area.