Antarctic Sea-ice Extent Oscillation Index with the Relationship Between ASEOI and Synoptic Climate in Summer of China

Sea ice is an important part of climate system and its change will influence local and regional circulation, even global climate change. Recently, Arctic Oscillation (AO) and Antarctic Oscillation (AAO) and their impacts on East Asia and global climate draw more attention of meteorologists. Cheng et al. find a teetertotter characteristic of sea ice concentration between the peripheries of Ross Sea and Bellingshausen Sea, and define the differences between them as the Antarctic Sea-ice Oscillation Index (ASOI). However, it's hard to define the scopes of these two regions exactly. In this study, a new index, ASEOI is built, as the difference of sea ice extent between Ross Sea Region and Antarctic Peninsula Region. Higher ASEOI represents less sea ice in Ross Sea Region and more sea ice in Antarctic Peninsula Region. Results indicate that this new index can well account for the impacts of prophasic sea-ice variations on atmospheric circulation and synoptic climate.The correlation analysis between ASEOI and SOI indicates that lower ASEOI in the previous spring of Southern Hemisphere (SH) will cause stronger Southern Oscillation (SO); lower ASEOI in the previous autumn of SH will lead to weaker SO from June to September. ASEOI can be used as an indicator of precipitation in the lower and middle reaches of Yangtze River and temperature in North China and South China. Taking ASEOI in October as examples, if ASEOI in the preceding October is below normal, the precipitation in the middle and lower reaches of Yangtze River in July would be more and the flood would be easy to build there, while the temperature would be higher in most part of North China and lower in South China. As it is known, less precipitation usually comes with the hot weather, and this would undoubtedly intensify drought in North China.This research helps the better understanding of interaction between Antarctica sea ice and atmospheric circulation and cognize the physical processes of sea-ice-air interaction in Antarctica, and offers helpful reference for further discussing the relationship between the variations of Antarctic sea ice and atmospheric circulation or synoptic climate. At the same time, it helps develop the correlative numerical simulation and seek the strong prognosis signals of Antarctica to the short-term climate influence on China.