A Monthly Atmospheric Circulation Classification and Its Relationship with Climate in Harbin

In this study, the classi cation scheme developed by Jenkinson and Collison (1977) based on a typing scheme of Lamb (1950) is applied to obtain circulation types from the mean sea-level pressure on a monthly basis. Monthly mean sea-level pressure data from 1951 to 2002 are used to derive six circulation indices and to provide a circulation catalogue with 27 circulation types. Five major types (N, NW, C, CSW, and SW) which occurred most frequently are analyzed to reveal their relationships with the temperature of Harbin on various time scales. Stepwise multiple regression is used to reconstruct temperature anomaly. The monthly mean rainfall of all types occurring and the composite maps of three major types (C, CSW, and SW) relevant to Harbin's precipitation are studied. The results show that the dominant types in winter are types N and NW. types C, CSW, and SW occur frequently in summer. Types N and NW favor a negative temperature anomaly and correspond to less rainfall, while types C,CSW, and SW often induce a positive temperature anomaly and correspond to more rainfall. Moreover, a successful statistical model can be established with only one of the six indices and large-scale mean temperature. Using the model, 77.3% of the total variance in the temperature anomaly between 1951 and 2002 can be reconstructed. Type C has a close relationship with total rainfall and type C precipitation plays a major role in determining the total rainfall of Harbin in recent years. This classification scheme is a statistical downscaling model and its relationships with temperature and precipitation can be used to forecast regional climate.