Interdecadal Variation And Attribution Of Climate Change Of Cold Events Over Asia During Holocene

The Holocene is a key period for understanding the past and the present,for predicting the future,it is of great scientific and social significance for understanding the response of Asian climate to cold events,predicting climate change,and making scientific decisions under similar climate background in the future.In this paper,the results of the all forcing run and four single-factor run of the past 21000 years Simulation of Transient Climate Evolution over the last 21000 years(TRACE-21ka)conducted by Community Climate System Model 3(CCSM3)are analyzed,based on the verification of the reliability of the model for the simulation results of cold events in Holocene and precipitation in Asia,the Empirical Orthogonal Function decomposition(EOF)and correlation analysis are used to diagnose the climate,to explore the characteristics of interdecadal climate change and the mechanism of precipitation change in Asia after the cold event.The temporal and spatial characteristics and causes of the interdecadal variations of precipitation in Asia during the cold event are analyzed as well.The main conclusions are summarized as follows:1.The change of variation characteristics of interdecadal climate after the Holocene cold eventThe cooling effect of the 8.2ka cold event is the most evident of all Holocene cold events and the temperature variation between-1.31-0.38? while the cooling effect of 4.2ka event is the least evident and the variation is between-0.40-0.60?The change of spatial distribution of Asian inter-decadal temperature after 9.5ka cold event is different from other events,the temperature increased significantly in East Asia.The change of spatial distribution in inter-decadal temperature variation under Asia after other typical cold events shows that the temperature decreased at high latitudes while increased at low latitudes.The decrease of precipitation is the greatest after 6.3ka cold event,while it is generally moisture after 9.5ka cold event.The area extent of decrease is the greatest after the 8.2ka event.The spatial variation characteristics after 8.2ka and 4.2ka cold events are relatively similar.The precipitation distribution pattern in East Asia is south flood and north drought.The precipitation in India uniformly decreased,and the precipitation in the central-western Pacific decreased while increases in the north pacific.2.Temporal and spatial variations of interdecadal precipitation in Asia during each typical Holocene cold eventBased on extracting the interdecadal signals of precipitation in the all forcing run,the temporal and spatial characteristics of the inter-decadal precipitation change in Asia under each cold event were studied by empirical orthogonal function decomposition.Analysis reveals:The interdecadal spatial modes of precipitation in Asia during each cold event during the Holocene are roughly the tripole distribution of the reverse change between Southeast Asia and the rest of Asia,except for the 9.5ka and 4.2ka cold event.The extreme center of precipitation in Asia under each cold event is located in the equatorial central and western Pacific Ocean east of the Philippine Islands,but the range of precipitation zone during each cold event varies.There is a significant quasi-25-year cycle of precipitation in Asia under each cold event.There are 28-year cycle and quasi-70-year cycle in 9.5ka cold event,quasi-20-year cycle in 8.2ka cold event,a 22-year cycle and quasi-40-year cycle in6.3 ka cold event There are 25-year period and quasi-75-year period in 4.2ka cold event and 26-year period in 1.5 ka cold event in late Holocene.3.The influence of different external forcing factors on the spatial and temporal variation characteristics of inter-decadal precipitation in Asia during the cold eventAfter extracting the inter-decadal signals of Asian precipitation in the all forcing run and four single-factor forcing run,the empirical orthogonal function decomposition,spatial correlation analysis,power spectrum,and other methods are used,the temporal and spatial characteristics of inter-decadal precipitation changes in Asia under various cold events are investigated.The analysis finds:During 9.5ka,8.2ka,and 1.5ka cold events,the interdecadal precipitation spatial modes in Asia are most affected by ICE forcing,and the 4.2ka cold events are most affected by MWF forcing.During the 6.3ka cold event,the inter-decadal precipitation spatial mode in Asia is most affected by GHG forcing.The temporal variation characteristics of inter-decadal precipitation in Asia are most affected by ORB during the 9.5ka and 6.3ka cold events.During 8.2ka and 1.5ka cold events that occurred,ICE has the greatest influence.During 4.2ka cold events that occurred,MWF has the greatest influence.