Source area scale variations in urban snow cover and its impact on the radiation budget

The complexity of urban structures and processes provide challenges in the assessment of climatological properties in urban regions. This is further complicated in the winter season of mid-latitude regions by the spatially and temporally variable presence of snow. To date, few experimental studies have examined urban climate processes in winter. To improve understanding of the spatially complex urban surface and its relation to winter urban climates, a study was conducted in Montreal to assess the dynamics of urban snow cover at the measurement source area scale. High resolution aerial photographs were obtained in the winter of 2008 to study the spatial and temporal variation of snow cover. Photos were taken at scheduled intervals following snow fall events (IOPs) in order to demonstrate high levels of variation and evolution. Radiative and turbulent source areas were modelled during the IOPs and spatial statistics illustrate snow cover variation within them. Implications of these results to urban climate parameters, specifically the energy balance, are discussed.