Fog Characteristics on the NSR

(from Navigational Book 4151; translated from Russian)

In summer visibility over Arctic seas can be reduced by precipitation especially in the areas of atmospheric lows, but more frequently it is reduced by fog. Fogs are common during the summer months and are mainly caused by an influx of relatively warm and moist air from the Atlantic and Pacific Oceans. Ice thawing in the summer also leads to the formation of stable fog and low clouds. Fogs are most frequently observed close to the edge of the sea ice, but not necessarily near the shore. Maximum number of days with fog occurs in July and August, up to 24-29 per month. On small islands lying within the NSR area the number of days with fog is somewhat less, or 22-24 per month. The average number of days with fog is 14-17 days per month on the continental shore and on the coasts of large islands, and 8-10 days per month over gulfs and bays.

At a distance of over 250 miles offshore and in the absence of ice, fogs occur frequently during winds blowing from the south. But, at a distance of 50-75 miles offshore fogs are more common during winds blowing from the north. In the presence of sea-ice fogs become equally frequent during winds blowing from the south and north. Fogs occur most frequently when air temperature is 0°C to +5°C, but fogs are also observed when the temperature is below 0°C (up to -5°C). Fogs are most frequently observed in the northern part of the Kara Sea, but are also frequently observed in the northern parts of the Barents and East Siberian Seas, and in the southern part of the Chukchi Sea.

In summer fogs last on average for 4-6 hours along the coast and 7-9 hours in the northern part of the NSR area. Sometimes fogs can last for 4 days. Fogs lasting 1-3 hours make up 35- 40% of the total number of fogs. Fogs in July and August lasting 1-1.5 days account for only 2-4%. Fogs lasting 2 or more days are more frequent (up to 2%) in the northern part of the Kara Sea, in the southern part of the Chukchi Sea, and in the western part of the Arctic Basin.

Generation of a fog by "charge" when the duration of a "charge" is less than 1 hour is observed rather frequently. Normally fogs are formed during gentle and moderate winds. Fogs occurring during winds with speed of more than 8 m/sec make up 25-30% of the total number of fogs.

State hydrographic department of the Ministry of Transport of Russian Federation, 1996, Fog Characteristics on the NSR, .©