科研之友
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摘要
Mechanism of arid central Asia climate dynamics is still an open question even it has been studied for a long time. Interpreting climatic proxy data properly is crucial for better understanding the paleoclimate in such a sensitive area and its role in the earth system. According to the analysis of water stable isotope (delta O-18 and delta D), Lake Barkol catchment obeys the typical isotopic model of a hydrologically closed lake: Lake input water inherits the feature of the weighted mean annual isotopes in precipitation, and lake water isotopes move along the local evaporation line from the start point of input water isotopes, modulated by the regional effective moisture. Based on the modern water isotopes and its relation to the climate, sediment carbonate oxygen isotope (delta O-18 carb) record reinterpretation suggests that the Asian monsoon incursion to arid central Asia area alone is unlikely the reason for the early Holocene delta O-18 carb negative, as the calculated extreme summer rainfall delta O-18 change to compensate the more negative delta O-18 carb in the early Holocene is far beyond our knowledge of precipitation isotopes in the real world. Besides, a 40 % of winter precipitation increase could explain the delta O-18 negative change in the early Holocene, which does, more importantly, reconcile the contradiction between the pollen Aretemisia/Chenopodiaceae effective moisture and delta O-18 records.
