To quantify the impact of urbanization on changes in observed surface air temperature and extremes,a homogenized dataset of daily mean,maximum and minimum temperature(Tm,Tmax and Tmin)observations at 20 stations in Gr...To quantify the impact of urbanization on changes in observed surface air temperature and extremes,a homogenized dataset of daily mean,maximum and minimum temperature(Tm,Tmax and Tmin)observations at 20 stations in Greater Beijing(GBJ)from1978 to 2008 is analyzed.In contrast with previous studies,a cluster analysis is done to objectively classify observing stations into four categories(urbanized,suburban,rural and mountain),which is checked with remote-sensing night-light images since the1990s.At urbanized sites,there is an added warming trend in annual mean Tm representing an average of 10.9%(up to 18.4%or0.12°C/decade at the most strongly influenced site)of overall warming.Corresponding contributions for Tmin are 12.7%(up to20.8%or 0.19°C/decade)and 24%for diurnal temperature range DTR(up to 37.4%or 0.149°C/decade)over the last three decades.Although it has not had a significant impact on daytime records(Tmax),urbanization has enhanced the increasing(decreasing)trend of extremely warm(cold)nights by an average of 12.7%or 2.07 d/decade(29.0%or 5.06 d/decade)at the urbanized sites since the 1970s.展开更多
基金supported by the National Natural Science Foundation of China(41075063)the Chinese Academy of Sciences(XDA05090000)
文摘To quantify the impact of urbanization on changes in observed surface air temperature and extremes,a homogenized dataset of daily mean,maximum and minimum temperature(Tm,Tmax and Tmin)observations at 20 stations in Greater Beijing(GBJ)from1978 to 2008 is analyzed.In contrast with previous studies,a cluster analysis is done to objectively classify observing stations into four categories(urbanized,suburban,rural and mountain),which is checked with remote-sensing night-light images since the1990s.At urbanized sites,there is an added warming trend in annual mean Tm representing an average of 10.9%(up to 18.4%or0.12°C/decade at the most strongly influenced site)of overall warming.Corresponding contributions for Tmin are 12.7%(up to20.8%or 0.19°C/decade)and 24%for diurnal temperature range DTR(up to 37.4%or 0.149°C/decade)over the last three decades.Although it has not had a significant impact on daytime records(Tmax),urbanization has enhanced the increasing(decreasing)trend of extremely warm(cold)nights by an average of 12.7%or 2.07 d/decade(29.0%or 5.06 d/decade)at the urbanized sites since the 1970s.
