Moisture-advection feedback supports strong early-to-mid Holocene monsoon climate on the eastern Tibetan Plateau as inferred from a pollen-based reconstruction
Moisture-advection feedback supports strong early-to-mid Holocene monsoon climate on the eastern Tibetan Plateau as inferred from a pollen-based reconstruction
复制标题
DOI：
10.1016/j.palaeo.2014.02.022
复制
发表时间：
2014-05
期刊：
影响因子：
--
通讯作者：
U. Herzschuh;J. Borkowski;J. Schewe;S. Mischke;F. Tian
中科院分区：
文献类型：
--
作者：
U. Herzschuh;J. Borkowski;J. Schewe;S. Mischke;F. Tian
（古）气候学家面临的挑战，以确定机制，导致所观察到的突然全新世季风事件，尽管事实上，季风环流被认为是由逐步日照变化。在这里，我们提供代理和模型的证据表明，水分平流反馈可以导致海面和大陆温度和季风降水之间的非线性关系。西门错湖的花粉记录（年宝也则山）表明，末次盛冰期后青藏高原东缘植被以高山荒漠和冰川植物群为特征（21-15.5 cal kyr BP），冰川晚期的高山草甸（15.5-10.4 cal kyr BP）和全新世后半期（5.0 cal kyr BP至今）以及全新世前半期（10.4-5.0 cal kyr BP）的混交林。基于花粉的传递函数的应用在10.4 cal kyr BP处产生温度突然升高，在5.0 cal kyr BP处产生约3 °C的温度降低。通过应用端元建模粒度数据从同一沉积物的核心，我们推断，频繁的河流事件（可能源于高量级的降水事件）更常见的早，中期全新世。我们分配推断异常强季风环流的启动水分平流反馈，一个简单的模型，再现这种反馈模式在同一时期的结果支持。
(Paleo-)climatologists are challenged to identify mechanisms that cause the observed abrupt Holocene monsoon events despite the fact that monsoonal circulation is assumed to be driven by gradual insolation changes. Here we provide proxy and model evidence to show that moisture-advection feedback can lead to a non-linear relationship between sea-surface and continental temperatures and monsoonal precipitation. A pollen record from Lake Ximencuo (Nianbaoyeze Mountains) indicates that vegetation from the eastern margin of the Tibetan Plateau was characterized by alpine deserts and glacial flora after the Last Glacial Maximum (LGM) (21–15.5 cal kyr BP), by alpine meadows during the Late Glacial (15.5–10.4 cal kyr BP) and second half of the Holocene (5.0 cal kyr BP to present) and by mixed forests during the first half of the Holocene (10.4–5.0 cal kyr BP). The application of pollen-based transfer functions yields an abrupt temperature increase at 10.4 cal kyr BP and a decrease at 5.0 cal kyr BP of about 3 °C. By applying endmember modeling to grain-size data from the same sediment core we infer that frequent fluvial events (probably originating from high-magnitude precipitation events) were more common in the early and mid Holocene. We assign the inferred exceptional strong monsoonal circulation to the initiation of moisture-advection feedback, a result supported by a simple model that reproduces this feedback pattern over the same time period.