Anomalies of Central England Temperature Classified by Air Source

Abstract

Daily anomalies of mean central England temperature (CET), relative to daily 1961?90 climatology, are analyzed in terms of the source of the air estimated from fields of mean sea level pressure. The average CET anomaly for a given source and calendar month during 1961?90 is taken as an estimate of the influence of atmospheric circulation for that source and calendar month, and the uncertainty in this influence is provided by the associated standard error. The atmospheric circulation influences are subtracted from the daily CET anomalies since the late nineteenth century to yield ?residual anomalies,? which represent the influence of forcings other than atmospheric circulation. The use of air sources captures more circulation-related daily CET variance than the airflow indices used in previous studies. The warming in central England since the 1970s is not predominantly a result of atmospheric circulation changes, and the long-term changes of CET for air from major source regions are on the whole very similar to each other and to the overall long-term changes.