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Effects of site change and urbanisation in the Beijing temperature series 1977–2006

During 1977–1981 the Beijing (BJ) meteorological station was at a suburban location. In 1981 it was moved to a more urban location, but in 1997 it was subsequently moved back to the same suburban location. The daily BJ temperature series, together with those from 18 nearby stations, form a unique database for studying how site‐change and possible urbanisation influences affect climate changes at a local scale. The site‐change‐induced biases were quantified, between 0.43 and 0.95 °C, based on comparisons between multi‐year‐mean seasonal temperature anomalies at BJ and the mean of those from a cluster of nearby stations. The annual mean urban‐suburban difference was 0.81 °C around 1981 and 0.69 °C around 1997, indicating a growing urbanisation effect in the suburban compared to the downtown area. The linear warming trend in the adjusted (for site moves only) BJ temperature series during 1977–2006 was 0.78 °C/decade. Comparing with several rural and less‐urban sites, we suggest that the BJ records include an urbanisation‐related warming bias between 0.20 and 0.54 °C/decade, likely about 0.30 °C/decade, for the recent few decades. The climatic warming at BJ between 1977 and 2006 is likely, therefore, to be about 0.48 °C/decade. Caveats for using these estimates were discussed. Copyright © 2009 Royal Meteorological Society