Evaluating the Role of Snow Cover in Urban Canopy Layer on the Urban Heat Island in Sapporo, Japan with a Regional Climate Model

Journal of the Meteorological Society of Japan. Ser. II

Tomonori SATO²  Keisuke MORI¹ 

[1] Graduate school of Environmental Science, Hokkaido University, Sapporo, Japan;Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan

关键词: urban climate;    urban heat island;    snowy urban;    regional climate model;    urban canopy model;   

DOI  :  10.2151/jmsj.2015-039

学科分类：大气科学

来源: Meteorological Society of Japan

【 摘 要 】

 Climate monitoring in urban areas is important because climate change in densely populated areas has a strong influence on society. The rate of long-term temperature increase in high-latitude snowy urban areas is relatively large due to global warming and urban heat islands. However, the influence of snow cover on urban heat islands is unclear. The purpose of this study is to assess the effect of snow cover in urban canopy layer on winter heat islands using a mesoscale atmospheric model coupled with an urban canopy model. Numerical experiments indicate that snow cover in urban areas serves to decrease surface air temperature, with a stronger decrease in daily maximum temperatures (0.4-0.6°C) than daily minimum temperatures (0.1-0.3°C). The increase in surface albedo is primarily responsible for the decrease in net shortwave radiation and sensible heat flux. In addition, increased evaporation causes a weakened sensible heat flux. The estimated snow cover effect during the day is comparable with the typical magnitude of anthropogenic heat release. In urban canopy layer, snow cover on roofs plays a significant role in reducing surface air temperature. Snow clearing on roads tends to increase nocturnal surface air temperature, especially in suburban areas because decreased snow depth increases ground heat transfer. These results indicate that snow cover in urban canopy layer reduces surface air temperature, resulting in weakened urban heat islands.

【 授权许可】

Unknown