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In summer 2013, mainly from July to August, most parts of China continued to experience an unusually severe heat
wave with exceptionally high air temperatures, based on the records measured at meteorological stations. As a
supplement to the weather station networks, remotely sensed observation can quantify detailed variation of surface
temperature at relatively high spatial resolution, owing to its ability to provide a complete and homogeneous data sources.
In addition to the GHCN CAMS gridded land air surface temperature, land surface temperature products of MODIS
including MOD11C3/MYD11C3 and MOD11A2/MYD11A2 were used to evaluate the anomaly of summertime thermal
environment over the South China in 2013. To investigate the impacts of heat wave event on built environment, the
MODIS Land Cover Type yearly product (MCD12Q1) was collected. Regional thermal anomaly was observed in both
air and surface temperature measurements, especially for August. Statistics based on MOD11A2/MYD11A2 shows the
spatio-temporal variation of land surface temperature at regional scale, and the heterogeneous characteristics in diurnal
cycle are also shown. Compared with other types, the urban and built-up generally presents larger surface temperature at
daytime. Detailed analyses were further conducted for three selected regions roughly covering the Yangtze River Delta,
the Pearl River Delta, and the areas around Wuhan City respectively. Findings indicate that urban and built-up exhibits
more distinct thermal contrast to its surroundings at daytime, in contrast to the situation at nighttime. This thermal
contrast was defined as surface urban heat island intensity (UHII) calculated using a newly proposed procedure, in this
paper. The UHII shows both time- and geography-dependent variations. Meanwhile, the UHII over medium and small
cities was even more obvious and larger than that over megalopolitan areas. These preliminary findings suggest that land
use and land cover changes as a consequence of rapid urbanization possibly gives positive feedback to warming anomaly
during heat wave event. The exacerbated warming of built-up environment, not only over megalopolitan areas but also
over medium and small cities, deserves our attention in urban management.
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