Acta Geographica Sinica ›› 1999, Vol. 54 ›› Issue (2): 125-133.

### LONG TERM VARIABILITY OF THE SIBERIAN HIGH AND THE POSSIBLE CONNECTION TO GLOBAL WARMING

Gong Daoyi, Wang Shaowu

1. Department of Geophysics, Peking University, Beijing 100871
• Received:1998-06-24 Revised:1998-10-14 Online:1999-03-15 Published:1999-03-15
• Supported by:
Supported by National Natural Science Foundation of China,No.49635190

Abstract: The Siberian High is one of the most important circulation systems influencing the climate of eastern Asia in winter. In this study, the intensity index of the Siberian High is defined as I=? 苮72n=1Pnδncosφn? 苮72n=1δn cosφn where Pn is the sea level pressure at grid n , φn is latitude, δn =1 when Pn ≥1 028 hPa, and δn =0 when Pn <1 028 hPa. This index indicates the level of anomaly from the average atmospheric conditions in the core region of the Siberian High. A long time series of the intensity index for the last hundred years was established on the basis of monthly mean sea level pressure data for the northern hemisphere obtained from CRU/UEA. Power spectrum analysis reveals that, for about four decades, the index showed decadal variability. In the 1960s, the Siberian High’s intensity was the highest. During the late 1980s and the early 1990s, the intensity was the lowest. The intensity was strongly correlated with the winter temperature of East Asia. A great deal of the temperature variance in the region 110°E～140°E and north of Bangladesh can be explained by the intensity index. Our calculation of the temperature data for 65 winters shows that 43 6 percent of the variance of North China’s winter mean temperature can be accounted for by the intensity of the Siberian High. The possible impact of global warming on the variability of the High was also investigated using the atmosphere ocean coupled general circulation model (HADCM2). The result of CO2 increase at the rate of 1% per year on global warming was compared with the result of control integration. It was found that in the last hundred years the impact of global warming on the Siberian High was not evident and that the High’s own natural variability played a more important role. Continuous warming in the future will significantly reduce the intensity of the system. However, the change will not be linear. With increasing Co2, variability at 5～6 year inter annual scale can be expected to become more prevalent.

CLC Number:

• P467