Dust Deposition Researches In Westerly Region In Xinjiang

By using an 18.7m ice core retrieved form Middle West Kunlun Mountain inSouth Xinjiang, we reconstructed the dust flux and snow accumulation rate of near 90years of last century, and the dust deposition characteristic in the ice core is gotten.We also sampled 7 loess profiles in North Xinjiang; they are respectively ZKT, XYZ,XYZ+ and XY section in Yili region; BL section in Bole region; LL1 and LL2 inTacheng region. By using the loess samples, we reconstructed the environmentalchange of North Xinjiang since the last interglacial period.The ice core provides us an opportunity to comparative analysis the weatherstation of low altitude surrounding Taklimakan Desert represented by Hotan and theclimatic proxy of high altitude surrounding Taklimakan Desert represented byChongce Ice-core. Wavelet analysis were used to investigate the climatic variations ofpatterns, cycles and frequencies of different altitudes from 1954 to 1992, and differentresponses of different altitude surrounding Taklimakan Desert to global warming weregot: Coherent decline of snow accumulation rate and dust deposition of high altituderecorded in Chongce ice core; Coherent increase of summer half-year precipitationand SAT(surface air temperature) of Hotan; Consistent variation tendency betweendust deposit recorded in Chongce ice core and Hotan spring sandstorm days; Oppositevariation tendency between Hotan precipitation and Chongce ice core snowaccumulation rate and consistent cycles in general.By analyzing the mechanism of different response, determined the predominantfactors of different altitudes: At the low altitude, the vapor supply is predominant, andmore vapor supplying means more precipitation; At the high altitude, probably thepopulation of dust aerosol which act as cloud ice nuclei in high altitude atmospheretakes advantage over the vapor supply to affect the precipitation, and the dust aerosolpopulation reducing result in the wet deposition reducing, thus the dust aerosol is thepredominant factor.By using the typical loess profiles ZKT and LL2, we reconstructed theenvironmental evolution of North Xinjiang since the last glacial period. We used the＜2μm grain size content to reflect the precipitation variations;＞63μm grain sizecontent to reflect the sandstorm variations;＜10μm grain size content to reflect thestrength of the westerlies. Although the change characteristics are different in detail,the overall changing trends are consistent. Combined with the TOC, CaCO3 content,magnetism characteristic and the Chromaticity; we found the North Xinjiangenvironment present a warm-dry characteristic in inter-glacial period and stages, and a cold-wet characteristic in glacial period and stages, since last inter-glacial period.Compared with the Loess Plateau, Tibetan Plateau, Polar region and the NorthAtlantic region since last inter-glacial period, the paleoclimatic characteristics show aconsistent variation trend in the cold-warm, i.e. the temperature variation is controlledby the global change; but the wet-dry variations are different, show a regionalcharacteristic, opposite to the Loess Plateau.