湖泊沉积物记录的过去两千年青藏高原南部干湿变化及其驱动机制

Climatic Changes During the Last Two Millennia on the Southern Tibetan Plateau Based on Lake Sediment and Its Forcing Mechanisms

基于青藏高原南部过去2000 a高分辨率的降水/湿度重建序列,通过区域对比以及集成分析方法,探讨了青藏高原南部过去2000 a气候干湿变化的时空特征,并对典型时段中世纪暖期(AD 600-1400年)和小冰期(AD 1400-1900年)高原南部气候变化的特征和机制进行了着重探讨.结果显示:整体而言,过去2000 a青藏高原南部气候变化显著,表现出AD 1-600年由湿转干、AD 600-1400年干旱以及AD 1400年后湿润的特征;对比分析表明,青藏高原南部在中世纪暖期和小冰期“暖干”/“冷湿”的特征,与高原东南部以及西北部地区相似,而与高原东部地区相反;过去2000 a青藏高原南部气候干湿变化可能与印度季风和西风强度变化、西风在青藏高原上的季节性移动以及蒸散发强度变化有关.

Based on the high resolution precipitation/moisture series over the Southern Tibetan Plateau in the past two millennia,the spatiotemporal pattern of drought-wet change over the Southern Tibetan Plateau are discussed by regional comparison and integrated analysis.The characteristics and mechanisms of climate change during the two typical periods,i.e.the Medieval Climate Anomaly(MCA,AD 600-1400)and the Little Ice Age(LIA,AD 1400-1900),are discussed emphatically.The results show that climate over the Southern Tibetan Plateau has changed significantly in the past two thousand years.It changed from wet to dry in AD 1-600,keeping dry in AD 600-1400,and then wet after AD 1400.The LIA and MCA climate conditions on the Southern Tibetan Plateau were found to be generally similar to those in the south-eastern and Northwestern Tibetan Plateau areas,but anti-phase with those in the Southwestern and Eastern Tibetan Plateau areas.The variation of dry and wet climate over the Southern Tibetan Plateau in the past two thousand years may be related to the intensity changes of Indian monsoon and westerlies,the seasonal movement of westerly jet over the Tibetan Plateau,and the intensity changes of evapotranspiration.