Winter temperature anomalies of the North China Plain and macroscale extratropical circulation

Monthly temperature anomaly data for 38 weather stations in the North China Plain and its vicinity were analyzed for winter months (November-March) du ring 1951-1992. The study area was divided into two subregions based on pri ncipal component analysis. Spearman's rank correlation coefficients between the scores of the temperature anomaly principal components and geopotentia l height anomalies in the Eastern Atlantic-Eurasia-Western Pacific realm su ggested different macroscale circulation patterns that influence the spatia l variation of temperature anomalies in the subregions. Temperature anomali es in the southern subregion were more closely related to the northern Asia n teleconnection pattern, while those in the northern subregion were more c losely related to the Eurasian pattern. Composite maps of geopotential heig ht anomalies indicated that the extreme positive and negative temperature a nomalies in the southern subregion were probably associated with the wideni ng and narrowing of the Asian trough, while those in the northern subregion were associated with the filling and deepening of the trough. The characte ristics of the Asian trough were strongly influenced by the variation of th e geopotential heights over Siberia. In stepwise regression, the teleconnec tion indices explained ca. 22 and 37% of the variation in the mean temperat ure anomalies in the southern and northern subregions respectively, indicat ing a stronger association between temperature anomaly in the northern subr egion and macroscale circulation patterns than that in the southern subregi on. Copyright (C) 1999 Royal Meteorological Society.