Conditions Responsible for Periods of Low Visibility along the West Coast of Greenland

The topography of Greenland often acts as a barrier to atmospheric flow and synoptic scale systems creating a large variety of weather situations in high latitude locations. A small number of studies have explored the seasonal variation and atmospheric conditions of low visibility at locations on the Eastern Coast of Greenland. This research aims to examine the surface weather conditions associated with time periods of low visibility (defined as reduced to 2 miles or less) at two West Greenland locations. Surface hourly observations were used for Thule Air Base (AB) and Sondre Stromfjord (SS) from 1952- 2018. A total of 11 weather classifications were created by grouping surface hourly manual and automated present weather codes (99 codes) by similar attributes (e.g., Fog, Blowing Snow). Results show a prominent relationship between the amount of low visibility hours, the type of weather classification, and the season for each weather station. Overall, Thule AB had many more hours of measured low visibility each month (2-100 times) compared to the SS location. Hours of low visibility peaked during the months of June, July, and August at Thule AB and were dominated by fog, while the hours of low visibility were a minimum during these same months at SS with precipitation as the dominant cause. Lastly, fewer weather classes were responsible for low visibility time periods during the Melt Season (JJA) compared to the Cold Season (DJF).