JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, D14113, 12 PP., 2011
Observed surface warming induced by urbanization in east China
- The rapid urbanization has significant impacts on temperature over east China
- A new method was developed to dynamically classify urban and rural stations
- Comparison of the trends of UHI effects by using OMR and UMR approaches
Xuchao Yang, Shanghai Typhoon Institute of China Meteorological Administration, Shanghai, China Institute of Meteorological Sciences, Zhejiang Meteorological Bureau, Hangzhou, China Yiling Hou, Shanghai Climate Center, Shanghai, China, Baode Chen, Shanghai Typhoon Institute of China Meteorological Administration, Shanghai, China
Monthly mean surface air temperature data from 463 meteorological stations, including those from the 1981–2007 ordinary and national basic reference surface stations in east China and from the National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, are used to investigate the effect of rapid urbanization on temperature change.
These stations are dynamically classified into six categories, namely, metropolis, large city, medium-sized city, small city, suburban, and rural, using satellite-measured nighttime light imagery and population census data. Both observation minus reanalysis (OMR) and urban minus rural (UMR) methods are utilized to detect surface air temperature change induced by urbanization. With objective and dynamic station classification, the observed and reanalyzed temperature changes over rural areas show good agreement, indicating that the reanalysis can effectively capture regional rural temperature trends. The trends of urban heat island (UHI) effects, determined using OMR and UMR approaches, are generally consistent and indicate that rapid urbanization has a significant influence on surface warming over east China. Overall, UHI effects contribute 24.2% to regional average warming trends. The strongest effect of urbanization on annual mean surface air temperature trends occurs over the metropolis and large city stations, with corresponding contributions of about 44% and 35% to total warming, respectively. The UHI trends are 0.398°C and 0.26°C decade−1. The most substantial UHI effect occurred after the early 2000s, implying a significant effect of rapid urbanization on surface air temperature change during this period.
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One of the most thorough and detailed comparisons of urban vs rural data is summarised at: http://wattsupwiththat.com/2011/04/04/an-investigation-of-ushcn-station-siting-issues-using-a-cleaned-dataset/ see especially the secon half of the post – by Mark Gibbas. This was published by SPPI and may therefore be seen as biased in the eyes of some, but remember that this is a small company putting its reputation on the line. IMHO the quality and integrity of the work speaks for itself.
steven mosher says:
July 28, 2011 at 3:02 pm
“The definition of ‘rural’ for GIStemp is a population of >10,000, (also airports are frequently classed as rural) ”
“Wrong.- that changed in 2010. Nightlights are now used.”
I stand corrected. I even mentioned nightlights but failed to remember to mention the change. Nonetheless there are some reservations about the use of nightlights particularly in reference to the historical growth and development of areas.
With UHI it is the growth and when it happened that matters and not the absolute urban size. With the GISS correction for Urban/suburban vs rural, nightlights provides the classification of size and therefore its treatment by homogenisation, but this is applied regardless of when a change of size that might affect temperature happened.
Heres a compare for East China urban-stations vs rural:
http://hidethedecline.eu/media/ARUTI/Asia/China/fig21.jpg
– taken from the new RUTI project (see China)
http://hidethedecline.eu/pages/ruti.php