A fog and low visibility climatology for selected stations in the Western Canadian Arctic
Date
2017-01-06
Authors
Khalilian, Vida
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A detailed examination of low visibility (LV) occurrences and the weather types
that cause low visibility, with a focus on fog, was performed for five weather stations in
the western Canadian Arctic, in the vicinity of the Amundsen Gulf area of the eastern
Beaufort Sea. A series of climatologies were developed that established patterns of LV
occurrence as a proportion of all observations and as a function of LV events caused by
fog. Frequency climatologies for other weather types were also performed; in particular,
for snow, blowing snow, rain, and drizzle. Annual climatologies were used to identify
trends in several weather parameters over the 1980-2015 period of study. Monthlies were
used to identify typical patterns of occurrence over the course of a year, and hourlies over
the course of a day. A dataset of multi-hour fog events was also created; some of these
were related to synoptic patterns. Analysis was also broken down by season.
Results indicate several things. Monthly climatologies showed considerable
diversity across the study area. Three distinct groupings were noted: Tuktoyaktuk and
Ulukhaktok with a maximum frequency of LV conditions in February, Aklavik and
Inuvik with a maxiumum frequency in October, and Sachs Harbour in August. The
February maximum in Tuktoyaktuk and Ulukhaktok was related to cold air temperatures
combined with small amounts of moisture from sea ice leads. The Alkavik and Inuvik
October maximum was related to moisture advected over land from remaining open
water, as well as diurnal snow melt adding moisture to the boundary layer that condenses
as the evening cools off. The August maximum in Sachs Harbour is a reflection of
proximity to open water and cold air temperatures.
Hourly climatologies in the spring/fall season showed most stations have
maximum occurrence of LV events caused by fog in the early morning. This is a radiative
effect; cooling overnight causes radiation fog that peaks in occurrence just as morning
begins. This peak is pushed into the midday in the winter, and is much weaker in the
summer, both reflections of the changing pattern of daylight hours.
Description
Keywords
Low visibility, Arctic, fog, Climatology, Beaufort Sea