Exploring patterns and potential impact of cloud cover at public satellite overpass times used for wildfires: a case study of two regions in Canada

Background Satellite-based remote sensing is important for managing wildfires. However, cloud cover could hinder its effectiveness. Aims We examine potential cloud cover impacts on satellite-based wildfire detection and monitoring in Canada, analysing spatio-temporal patterns and relationships with local fire conditions. Methods Geostationary Operational Environmental Satellite 16 (GOES-16) Clear Sky Mask (CSM) data at relevant satellite overpass times in Ontario and Alberta are used to characterise cloud cover at a variety of spatial and temporal scales. Two potential fire behaviour indicators are compared under cloudy and clear conditions. Key results Cloud cover can vary by time of day, seasonally and by sub-region. In general, cloud cover was lowest overnight, during July–August and typically greatest at the overpass time of the Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) instruments (13:30). Initial Spread Index (ISI) and Head Fire Intensity (HFI) distributions were similar under clear and cloudy conditions. Conclusions Satellite-derived active fire products will experience omission error rates varying in space-time and this could occur under potentially dangerous fire behaviour conditions. Care may need to be taken when relying on these products for fire monitoring and detection. Implications Wildfire-detection and monitoring strategies should leverage satellite, airborne and ground-based methods.