Positive or Negative? Urbanization-Induced Variations in Diurnal Skin-Surface Temperature Range Detected Using Satellite Data

Diurnal temperature range (DTR) is an important indicator for assessing the local climate change due to urbanization. Studies that focused on surface air temperature (SAT) have reported decreased DTRSAT in urban areas. However, this urbanization-induced effect becomes more complex with regard to land skin-surface temperature (LST), which is highly localized and extremely sensitive to land surface properties. We thus investigated the urban-rural DTRLST difference (DTRLST) over 354 cities across China using satellite-retrieved LSTs within 2008-2013. Our major findings include the following: (1) urban areas experience increased (decreased) DTRLST compared with rural areas on the annual average for the majority of cities located in southern (northern) China; (2) the DTRLST is mostly positive in warm months but negative in cold months. It generally becomes more positive from January to August and becomes more negative afterward; and (3) the DTRLST is positively related to the daytime surface urban heat island intensity; it is yet negatively correlated with the urban-rural difference in vegetation abundance. We consider these insights valuable for in-depth understanding urban thermal environment and will likely help improve urban planning.