Dew amounts and its correlations with meteorological factors in urban landscapes of Guangzhou, China

The aim of this study was to investigate dew amounts in different urban landscapes and to examine the correlations between dew amounts and meteorological factors in Guangzhou, China. Results indicated that the dew amounts at fine night were different from landscapes to landscapes. A significant difference was found in average dew amounts between forest landscape and residential landscape (forest landscape and commercial landscape, industrial landscape and residential landscape). The highest mean dew amounts in urban area were observed in forest landscape (0.034 mm night− 1), followed by industrial landscape (0.022 mm night− 1), commercial landscape (0.013 mm night− 1) and residential landscape (0.009 mm night− 1), respectively. For maximum dew amounts, a similar relationship like the mean dew mounts was found in urban measured landscapes, whose values in turn were 0.104 mm, 0.08 mm, 0.03 mm and 0.109 mm, respectively. Both the mean dew amounts night− 1 and maximum dew amounts in urban landscapes were significantly less than those (0.077 mm in mean value and 0.224 mm in maximum value) in their countryside. The mean dew amounts correlated positively with mean relative humidity; meanwhile it correlated negatively with daily evaporation and urban heat island, respectively. It was therefore concluded that urban forest landscape was an important site for dew deposit, urban environment was not favorable for dew condensation, and relative humidity, daily evaporation and urban heat island might be the most important three meteorological factors responsible for the dew amounts in urban area.