Assessment of urban effect on observed warming trends durng 1955-2012 over China: a case of 45 cities

Jin, K.; Chen, D.; Jiao, Q.; Xia, L.; Fleskens, L.; Mu, X.


This study aims at qualifying the contribution of the urban effect to the total warming recorded by 45 urban or suburban stations in China where rapid and extensive urbanization over the last few decades occurred. Partly due to differences in urbanization and stations’ geographic location, the total warming trends for 1955–2012 vary from of -0.10 to 0.49 °C and -0.03 to 0.64 °C per decade for the annual averaged daily mean and daily minimum temperature, respectively. A principal component analysis of seven factors on the siting and geographical coordinates of the meteorological stations shows three dominant factors (urban size, relative position of meteorological station to city center and geographic location of station) accounting for 87.1 % of the total explained variance. An index quantifying the impact of the first two dominating factors of the urban effect is proposed considering also the dominating wind direction. The positive correlation between the temperature trends and the index is significant (P¿