The effects of increasing surface reflectivity on heat-related mortality in Greater Montreal Area, Canada

Heat-related mortality is increasing as the result of climate change, extreme heat events and higher ambient temperature because of urban heat island (UHI) phenomenon. We coupled the Weather Research and Forecasting model (WRFV3.6.1) with a multi-layer of the Urban Canopy Model (ML-UCM) to investigate the effects of UHI intensity during the 2005 and 2011 heat wave periods in Greater Montreal Area (GMA), Canada. Each day of simulation is categorized into an air mass type using the Spatial Synoptic Classification. Using the non-accidental mortality data during summer period, the number of deaths above the expected mean anomalous daily mortality is calculated for each air mass classification. Results indicate that moist tropical plus and dry tropical weather have the highest rank in heat-related death. We assessed the effects of increasing surface reflectivity (ISR) on four meteorological parameters: 2-m air temperature, 10-m wind speed, 2-m relative humidity, dew point temperature, and four heat stress indices: National Weather Service - Heat Index, Apparent Temperature, Canadian Humid Index, and Discomfort Index (DI). ISR decreased air temperature by 0.6 °C, increased relative humidity by 2%, increased dew point temperature by 0.4 °C. The DI improved by 3% and heat-related mortality decreased by nearly 3.2% during heat wave periods in GMA.