选择临汾盆地陶寺遗址附近中梁黄土剖面为研究对象,通过分析磁化率、元素含量等的变化,结合AMS14C测年,重建该区域末次冰消期以来东亚夏季风(EASM)演化过程。认识如下:(1)中梁剖面磁化率和地球化学元素变化记录了自16 ka B.P.以来一系列短尺度气候波动事件,如新仙女木事件(YD)和10.2 ka B.P.、9.2 kaB.P.、4.2 ka B.P.降温事件,但8.2 ka B.P.降温事件在该区的记录并不明显,表明末次冰消期以来该地区的气候变化具有全球特征,但同时也受区域气候变化的影响;(2)东亚夏季风EASM在(16.6—6.0) ka B.P.持续增强,(7.6—6.0) ka B.P.达到最盛,6 ka B.P.以后呈现波动减弱的趋势;(3)东亚夏季风EASM在早全新世对太阳辐射有一定的滞后性,全新世中期与太阳辐射变化基本一致,表明东亚夏季风总体上受太阳辐射驱动,同时也受到北高纬冰盖的调控;冰盖以及冰川融水注入大西洋引起的北大西洋径向环流(AMOC)的减弱一定程度上抑制了东亚夏季风的强度,导致出现如新仙女木事件和9.2 ka B.P.东亚夏季风明显减弱事件。
亚洲夏季风是十分复杂的天气系统,并且其对我国降水量有着重要影响。目前已建立了许多亚洲夏季风指数定量地衡量亚洲夏季风的强弱,但由于各个指数的侧重点不同,导致其对我国降水量的相关性也有所差异。文章选取目前已建立的11种亚洲夏季风指数,根据定义利用1981~2016年NCEP/NCAR再分析资料计算各指数序列,同时分析其与我国降水量之间的空间相关性。结果表明:不同季风子系统对我国降水量影响范围不同,南亚夏季风指数主要与华北地区夏季降水存在正相关关系;东亚夏季风指数与我国西南、东部地区存在强相关性。根据定义将亚洲季风指数按所使用的要素类型分为气压场类、风场类、环流场类和综合类,以不同气候要素定义的季风指数其影响范围亦不同。此外,东亚夏季风指数影响区域的年内变率与我国雨带变率一致。The Asian summer wind is a very complex weather system, and it has an important impact on precipitation in China. Many Asian summer wind indices have been established to quantitatively measure the strength of the Asian summer winds, but due to the different focuses of each index, their relevance to the precipitation in China is also different. In this paper, we select 11 Asian summer wind indices that have been established so far, and use the NCEP/NCAR reanalysis data from 1981 to 2016 to calculate the sequence of each index according to the definition, and analyze the spatial correlation between them and the precipitation in China at the same time. The results show that different monsoon subsystems have different ranges of influence on precipitation in China, and the South Asian summer wind index mainly has a positive correlation with summer precipitation in North China;the East Asian summer wind index has a strong correlation with the southwestern and eastern regions of China. According to the definition of the Asian monsoon index, the Asian monsoon index is categorized
