Air Temperature on the NSR

(from Navigational Book 4151; translated from Russian)

Snow and ice thawing in summer results in air temperatures that remains close to 0°C. Large and abrupt air temperature variations are not common for the NSR zone. Number of days with air temperature above 0°C is almost the same along the parallel 75°N, and is approximately 40 days. Closer to the North Pole temperatures above zero usually occur in the second half of July, for 10 to 15 days. Maximum air temperatures in the open sea do not exceed +5°C. Isotherms distribution by zones, with very insignificant horizontal temperature gradients, is characteristic for the Arctic summer. In summer maximum air temperature deviations from the multi-year average occurs on land. The air temperature is higher, sometimes very significantly, in the coastal areas of Arctic seas which are under the influence of warmed up continent.

Air temperature in the Arctic depends much on the wind direction. Air temperature on the coast is 7 to 10°C higher during continental wind than during inshore wind. On islands 25 to 50 miles offshore this difference is 2 to 4°C and between the parallels 80° - 85°N it is 1°C. Air temperature also depends on the average wind speed. Temperature inversion occurrence rate is very high during the Arctic summer, and wind strengthening in the surface layer results in turbulent mixing of air layers, inversion breaking, and in surface air layer temperature rise.

Transition to mainly above-the-0°C air temperature occurs first in the SW-part of the Barents Sea, where the influence of warm currents is the greatest. In the SE-part of the Barents Sea steadily rising air temperatures arrive about 1.5 months later, and in the vicinity of the islands of Franz Josef Land about 2 months later, i.e. in the 3rd week of June. In the SW-part of the Kara Sea and in the southern parts of the Laptev Sea and East Siberian Sea change of air temperatures to above zero occur in the second half of June. In the northern parts of almost all Arctic seas, except for the Barents Sea and Chukchi Sea, air temperature change to above zero occurs by the end of the first week or the beginning of the second week of July. However, even in July temperature below zero can occur in any region of the Arctic.

In a similar way in autumn air temperature change to below zero takes place in different regions at different times. In northern parts of the Kara Sea and Laptev Sea, and in the central East Siberian Sea, it occurs in the third week of August. In the central parts of the Kara and Laptev Seas, the northern parts of the Barents Sea and Chukchi Sea, and in the coastal areas of the East Siberian Sea, such transition occurs in the third week of September. Above zero air temperatures hold longer in the southern parts of the Kara and Chukchi seas as a result of an inflow of warmer waters from the adjacent seas. In the SW-part of the Barents Sea below zero air temperatures begin to prevail in the second week of November.

State hydrographic department of the Ministry of Transport of Russian Federation, 1996, Guide to navigating through the NSR, .©