Synoptic Scale Weather and Coastal Fog Occurrence along Atlantic Canada during C-FOG

Abstract:

This reviews the large scale weather conditions for the September 2018 occurred during the C-FOG field project that took place on the eastern of the Avalon Peninsula, Newfoundland, Canada. Visibility and other meteorological parameters were measured at five C-FOG sites and the St John’s International Airport. Three sites at Ferryland were about 1 km from each other. Supporting measurements included surface winds, air temperature, humidity, radiation and cloud base height as well as turbulence radiative fluxes and microphysical parameters. Eleven fog events were observed at Ferryland. Each fog event was related to large scale cyclonic systems and surface relative humidity was above 90%. Days with fog occurred in groups separated by fog-free days. Composites of fog events and of fog-free days had significant differences of sea level pressure and 2-m humidity. Fog was also examined across Atlantic Canada by including measurements from Sable Island, Yarmouth, Halifax and Sydney, Nova Scotia. Results suggested that the most fog events occurred at Ferryland and the least at Sable Island. Fog occurrence tends to increase toward the west along Nova Scotia, to the south along the Avalon Peninsula and toward higher elevations for all stations. At Ferryland, all fog events occurred with a cyclonic system while Sable Island and Yarmouth events occurred under cyclonic and anticyclonic systems.