Western Arctic Climate
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At the regional scale, the climate of Alaska is controlled by polar and arctic air masses. In general, these air masses are characterized by low average annual temperatures and small amounts of precipitation, most of which is received in summer. These regions are characterized by strong seasonal fluctuations in solar energy and temperature, resulting in long severe winters and short mild summers. Temperature ranges characteristically exhibit greater annual ranges than diurnal ranges. Annual solar radiation intensity is characteristically low (Bailey, 2002). The study area is dominated by two climate divisions: the Tundra Division and the Subarctic division. The Tundra Division extends northward from the Arctic Circle to approximately 75°N and lies within the outer zone of the influence of Arctic Air masses. This climate is characterized by very short, cool summers and long severe winters. Average annual temperature of the warmest month is between 0 and 10 °C. Mean daily temperatures rise above 0 °C between 55 and 188 days (Bailey, 2001). Annual precipitation is low, though because of extremely low evaporation rates this climate is regarded as being humid. This climate is dominated by high pressure year round, which accounts for the prevailing low temperatures and lack of moisture, and experiences negligible invasion of cyclonic storms. The whaling villages found in this climate region include Kaktovik, Nuiqsut, Barrow, and Wainwright. The climate data in Table 1 illustrates the relatively low average maximum and minimum annual temperatures, and lack of overall precipitation and snow received in this climate.

The vast area of Alaska is dominated by a subarctic climate, which is dominated by continental polar air masses which form between 50-70 °N. This climate exhibits a large seasonal temperature range. Winters are severe, and summers are cool and short with only one month of the year with a mean temperature above 10 °C. As high pressure systems dominate the winter season, the relatively small amount of annual precipitation concentrated in the three summer months (Oliver 2002). The transition between summer and winter is abrupt, with extremely short spring and fall: the traditional times of whale hunting depending on specific location. While the two dominant climate types of tundra and subarctic are dominated by arctic and continental polar air masses respectively, in the Bering Sea region there is a strong maritime influence. Here, maritime polar air masses, originating in the north pacific, dominate the climate of the region. While these air masses are very similar in their characteristics to continental Polar air masses, they differ from them with respect to more moderate temperature and moisture characteristics. The influence of these air masses is well illustrated in the climate contrasts between Barrow, Barter Is. and Wainwright on one hand and Gamble, Kotzebue, and Wales on the other. These latter three stations all show substantially warmer average temperatures, and substantially greater amounts of average annual precipitation and snow depths.

The maritime polar air mass is dominated by low pressure, and this persistent low pressure cell is referred to as the Aleutian Low. This low pressure system is the dominant control on the weather of much of Alaska in the winter and spring time seasons (Wilson and Overland, 1987). Interannual variability in Alaskan climate, particularly as it relates to annual temperatures and storm tracks, is strongly tied to variability in the path of movement of the Aleutian low (Miller et al. 1994). Changes in the pathways and intensity of the Aleutian Low for example have been responsible for a marked warming in temperature in southern Alaska between 1976 and 1988 (Trenberth 1990). These marked changes have been related to the occurrence of ENSO events in the tropical oceans (Niebauer 1998, Mysak, 1986). More recently however, extratropical forcings have been proposed as the dominant influence on the strength and position of the Aleutian Low (Latif and Barnett 1994 ). These forcings are related to a pattern of Pacific climate variability referred to as the Pacific Decadal Oscillation, which is more strongly tied to subtropical gyre circulation than to the shorter frequency tropical ENSO forcings (Wiles 1997).

REFERENCES
Bailey, R.G. 2002. Ecoregions. In: Orme, A.O. (Ed.) The Physical Geography of North America. Oxford University Press. Oxford. pp235-245.

Latif, M. and Barnett, T.P. 1994. Causes of decadal climate variability over the north pacific and North America. Science, 266, 634-637.

Miller, A.J., Cayan, D.R., Barnett, T.P., Graham, N.E., and Oberhuber, J.M. 1994. Interdecadal variability of the Pacific Ocean: model response to observed heat flux and wind stress anomalies. Climate dynamics, 9, 287-302.

Mysak, L.A. 1986. El Nino, interannual variability and fisheries in the northeast Pacific Ocean. Canadian Journal of Fisheries and Aquatic Science, 43, 464-497.

Niebauer, H.J. 1998. Variability in Bering Sea ice cover as affected by a regime shift in the north Pacific in the period 1947-1996. Journal of Geophysical Research, 103 (C12) 27717-27737,

Oliver, J.E. 2002. Climatic regionalization. In: Orme, AO (Ed.) The physical geography of North America. Oxford University Press. Oxford. pp 112-129.

Trenberth, K.E. 1990. Recent observed interdecadal climate changes in the northern hemisphere. Bulletin of the American Meteorological Society. 71, 993-998.

Wiles, G. 1997. North pacific atmosphere-ocean variability over the past millennium inferred from coastal glaciers and tree rings. Preprints 8th Symposium on Global Change Studies. American Meteorological Society. Boston. PP 218-220.

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Weather for specific zones throughout AK

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Barrow Climatology

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