Variation in atmospheric dust since 1950 from an ice core in the Central Tibetan Plateau and its relationship to atmospheric circulation

Abstract

Variation in atmospheric dust deposited on the Tibetan Plateau (TP) and its response to climate change are not well understood. In this study, a 65-year annually resolved (1950–2014) atmospheric dust proxy record is presented from the Mugagangqiong (MGGQ) ice core in the central Tibetan Plateau. There is a significant positive correlation between the dust concentration of the MGGQ ice core and dust days observed from meteorological stations in the Taklimakan Desert (r = 0.47, p < 0.001) and the central TP (r = 0.50, p < 0.001), indicating that the MGGQ dust record provides a good proxy for reconstructing an annual history of atmospheric dust-loading in this region. Two periods of enhanced dust deposition, (1962–1968 and 1975–1987), characterised by high concentrations and coarse grain size, suggest enhanced aridity, strong winds and active dust storm events. The lowest dust deposition period was identified as being between 1988 and 2000. Here we utilise 1975–1987 and 1988–2000 as typical high and low dust-loading periods, respectively, to discuss the possible dust mechanisms with the JRA-55 reanalysis data. During the high dust-loading period, dust concentration and flux were positively correlated with the mid-latitude zonal wind, suggesting that the high-level westerlies strengthened in northwestern China and transported more dust to the central TP than during the low dust-loading period. Dust concentration and flux decreased from the late 1980s and were positively correlated with weakened zonal winds and negatively correlated with precipitation in northwestern China from 1988 to 2000. Weakening westerlies and increasing precipitation at the dust source areas were responsible for this decrease in dust-loading during this period.