Circulation Structure Features Of Western Pacific Teleconnection Pattern And Their Relation With China's Climate In Winter

The NCEP/NCAR global reanalysis monthly data, the NOAA Extended Reconstructed monthly SST from the Climate Diagnostics Center, The northern hemisphere monthly sea level pressure data set provided by the University of East Anglia and the monthly 160-station temperature and precipitation data set of the Chinese mainland provided by the National Climate Center are used in the paper. We present a study on the anomaly feature of western Pacific teleconnection pattern (WP) and their relation with the climate of China in winter from the point view of lager-scale circulation. The relationships between WP pattern and Arctic Oscillation (AO),Eastern Asian Jet (EAJ) were also analyzed. In addition, we discussed synthetically the effects of several climate factors on winter temperature over China. The main results show as following:In boreal winter, WP pattern have obvious the interannual and interdecadal variation characters. It can be observed in the whole troposphere and there is an equivalent barotropic structure in vertical direction. The differences of the circulation are extraordinarily notable between strong and weak WP pattern. In the higher WP index years (strong WP pattern) , the longitudinal pressure gradient enlarges and the middle latitude western wind is strengthened, the circulation is zonal pattern in East Asian . In accordance, the Siberian High (SB) and the East Asian winter monsoon (EAWM) are weak than normal. An inverse circulation sense was observed in the lower WP index years (weak WP pattern). In addition, the WP index positively correlates to the winter temperature and precipitation in China. In temperature aspect, significant correlations are concentrated in the region which begins from the eastern coast, goes to the south, then turns to the southwestern region, while only eastern region of China is significant to precipitation.The WP pattern is intimately related to the sea surface temperature (SST) in the tropical central eastern Pacific not only in winter but also the preceding summer season. From summer-autumn seasons the SST starts to affect the WP pattern and persists to the end of winter. The SST can affect strength of the EAWM by influencing WP pattern, WP pattern acts as a bridge between the EAWM and SST in the tropical central eastern Pacific. Further studies shows that WP is independent with SST in a certain degree. WP pattern is not entirely determined bySST and interior dynamic force is also important in the atmosphere.There are also some relationship between the WP pattern and ACK EAJ in winter. The AO can also affect strength of the EAWM by influencing WP pattern. The EAJ is weaker than normal when WP index is higher. An inverse sense was found in the lower WP index years. This indicates that WP pattern is related to not only low-latitude systems but also high-latitude systems, and to system not only in low troposphere but also in high troposphere.The western Pacific teleconnection pattern and SB have significant influence on winter temperature in China on the interannual timescale. WP pattern mainly influences the east of marginal areas from the south of the northeast China to coastal cities in Guangdong province. EAJ influences the central of China. The region associated with SB covers almost the entire China except for the upper reach of Yangtze and Huanghe River, which is larger than that associated with the WP pattern. However, the temperature is strongly affected by AO and ENSO on the interdecadal timescale. The area under the impact of ENSO includes North China and the middle and lower reaches of Yangtze River. Compared to ENSO, AO affects larger areas including the entire mainland except for some regions on the upper reach of Yangtze River.