中世纪暖期和现代暖期中国季风降水时空模式及其机制  

Spatiotemporal Model and Mechanism of Monsoon Rainfall in China During the Medieval Warm Period and the Current Warm Period

作　　者：崔英方[1,2] 赵侃[2] 赵彬[2] 王权 汪永进[2] Cui Yingfang;Zhao Kan;Zhao Bin;Wang Quan;Wang Yongjin(School of Tourism Management,Nanjing Institute of Tourism and Hospitality,Nanjing 211100,China;School of Geography,Nanjing Normal University,Nanjing 210023,China)

机构地区：[1]南京旅游职业学院旅游管理学院,江苏南京211100 [2]南京师范大学地理科学学院,江苏南京210023

出　　处：《南京师大学报（自然科学版）》2019年第4期145-152,共8页Journal of Nanjing Normal University(Natural Science Edition)

基　　金：国家自然科学基金(41702180);江苏省高校自然科学研究面上项目(16KJD170002)

摘　　要：IPCC第五次评估报告认为中世纪暖期(950-1250 A.D.)和现代暖期(20世纪增温)存在具有高可信度.气象观测结果显示20世纪中期以来的显著增温时期,中国降水变化呈现典型的"南涝北旱"两极模式.然而,这一模式与中世纪暖期代用指标重建降水所揭示的"南干北湿"模式存在显著差异,且这一差异的动力学机制亦不明确.继承大气降水氧同位素(δ18O)的中国石笋δ18O记录是描述水循环演变历史信息的理想天然示踪剂.本文将北京石花洞(中国北方)和贵州董哥洞(中国南方)石笋δ18O记录进行对比,基于δ18O-降水-大气环流信号之间的机理联系,解析中世纪和现代暖期大气降水时空模式及其机制.结果显示中世纪暖期石花洞石笋δ18O值显著负偏,指示亚洲夏季风增强,雨带北移,印度洋远源水汽输送增加,而南方洞穴石笋δ18O值相对正偏,指示降水减少或者蒸发加强,局地环流降水增加.在中世纪暖期,洞穴记录对比结果呈现与其他指标重建结果一致的"南干北湿"模式. 20世纪增温时期,石花洞与董哥洞石笋记录均显示δ18O值正偏过程,指示夏季风减弱,雨带南移,北方降水减少;南方降水则由近源水汽输送所控制.研究结果暗示中世纪暖期亚洲夏季风增强可能是气候自然变率的结果,而现代暖期季风减弱则可能与人类活动影响下的海温异常有关.The Fifth Assessment Report of the Intergovernmental Panel on Climate Change suggests that the existence of Medieval Warm Period( MWP,950-1250 A. D.) and Current Warm Period( CWP,warming in the twentieth century) is very likely. In CWP,annual precipitation anomalies over eastern China are characterized by a north-south dipole pattern,referred to as the"southern flooding and northern drought"pattern( SF/ND). However,spatial pattern of rainfall during MWP shows a"southern dry and northern wet"mode,revealed by paleoclimate reconstructions. Therefore,the mechanism of precipitation variations during the warm periods remains unclear. Inherited from the δ18O signal of precipitation,Chinese stalagmite δ18O records are ideal natural tracers for describing the history of the water cycle. Here,this paper compares stalagmite δ18O records from Shihua Cave,North China with δ18O records from Dongge Cave,South China,to explore the spatiotemporal model of rainfall and its mechanism in late Holocene. In MWP,negative δ18O values in northern China and positive δ18O values in southern China indicate that strong ASM intensity and associated northward progress of the rainband delivered more remote moisture from Indian Ocean to northern China and less to southern China. During the CWP,stalagmite δ18O values show a notable positive trend in both Shihua Cave and Dongge Cave,suggesting that weak ASM intensity and associated southward withdraw of the rainband resulted in the SF/ND pattern. Furthermore,local water vapor from the Pacific Ocean probably contributed to increased rainfall in southern China. The North( dry)-South( wet)pattern during the CWP inversely similar to the spatial pattern during the MWP,probably suggesting different impacts of natural and anthropogenic forcing on precipitation distribution.

关 键 词：中世纪暖期 现代暖期 氧同位素 降水 水汽输送 

分 类 号：K903[历史地理—人文地理学]