Synoptic Scale and Fog Occurrence at Ferryland, Newfoundland during C-Fog 2018 Field Program

A C-FOG (Coastal-Fog) field program took place on the southeast coast the Newfoundland Avalon peninsula and Atlantic Canada in 2018. Visibility and other surface meteorological variables were measured at Battery/Ferryland supersites on a low coast close to the ocean from Aug 18 to October 5. This point is in a broad zone of large scale climatic gradients in sea surface temperature, air temperature, and dew point. Eastward moving synoptic and mesoscale cyclones and anticyclones traverse over the area in rapid succession, sometimes in time scales less than 2 days. Fog occurred when the visibility was less than 1 km and occurred in 25 events lasting from 1 hour to 30 hours. Eighteen fog events occurred within 3 hours of sunrise and lasted 2-4 hours. All of these sunrise fog events occurred with an anticyclonic ridge or high center passing over the site within 3 hours of sunrise. An anticyclonic ridge or high center passing over the site greater than 6 hours of sunrise did not occur with fog. In addition, there were 2 longer fog events, one lasting 30 hours and one 11 hours which were associated with cyclonic conditions. The relation of coastal fog occurrence to synoptic scale weather systems will be discussed.