The Canadian Region

This region is one of the largest areas in the Arctic. Therefore, of course, the differentiation of climate is particularly evident here. The estimates of magnitude of these differences are, however, not identical. For example, Barry and Hare (1974) write, "The Canadian Arctic Archipelago extends over 15° of latitude but the climatic characteristics are relatively homogeneous". In turn, Maxwell (1982) noted that "...despite the northern latitudes of the Canadian Arctic Islands, the climate there is extremely diverse." Such divergences in opinion, according to Maxwell (1982), result from the fact that the majority of climatic classifications are based on data from individual stations, which are all situated in the coastal areas. This fact, as well as the use of mainly temperature and precipitation data in the process of climatic clas sification, introduces a bias in the results. This divergence may also result from the fact that Maxwell's (1982) work is of a regional character, so the greater detail is understandable, while other works describing climatic characteristics (Barry and Hare 1974) or presenting climatic classifications (Prik 1960, 1971; Atlas Arktiki 1985) for the entire Arctic must contain some element of generalisation.

In winter, as is demonstrated by the most recent data (Serreze et al. 1993), the frequency of both cyclones and anticyclones is similar, but rather low. The former dominate in the northern part of the Canadian Arctic, and the latter are prevalent in the western part. It is also important to add that the frequency of both these air pressure systems is significantly greater in the summer months (see Figure 2.3). However, both cyclones and anticyclones in summer and winter have been classified by Serreze et al. (1993) as relatively weak. This means that in the Canadian Arctic, the variability of climatic elements should be relatively low. Prik has distinguished two sub-regions in the Canadian Arctic: northern and southern (Prik 1971; Atlas Arktiki 1985).

In winter months very low temperatures are observed in the northern sub-region. The coldest temperatures in the entire Arctic (with the exception of Greenland) occur in the north-eastern part. The mean monthly temperatures here drop below -34°C and locally even below -38°C. Winds blow mainly from the northern sector and their speed is moderate or weak (in the northern part). Calms are very common and are noted for about 30% of all observations. Cloudiness is low, with the frequency of occurrence of clear and cloudy days amounting to 40-50% and 30-40%, respectively. Amounts of precipitation are also very low (< 10mm per month). The annual totals here are the lowest in the Arctic (see Figure 7.3).

The southern sub-region has higher temperatures (-20°C to -30°C) than those occurring in the northern sub-region due to the influence of both the latitude and a greater frequency of cyclones. The greater synoptic activity also causes an increase in the variability of air temperature and other climatic elements. Wind speed, cloudiness, and precipitation, similar to air temperature, are also higher here. The mean, very low temperatures in the Canadian Arctic, as noted Barry and Hare (1974) are connected with persistent rather than extreme cold.

During the summer, the significant influence of solar radiation (polar day), together with the lower temperature contrast in the time between high and moderate latitudes, markedly reduces the differences between the northern and southern sub-regions. Mean summer temperatures oscillate from 2 -4°C (in the North) to 6-8°C (in the South). A significant increase of local differentiation of air temperature may be observed, particularly between sea areas (which are full of drifting ice and therefore cold) and coastal non-glaci ated regions (which absorb great amounts of solar radiation and thus are relatively warm). The highest temperatures are, however, noted in the southernmost parts of the Canadian Arctic (>10-12°C). Winds are moderate and blow mainly from the northern sector. Cloudiness is higher than in winter. The frequency of cloudy days over the archipelago is 60-70%, decreasing over the continent to about 50%. This increase of cloudiness in summer is connected both with a greater occurrence of cyclones and with moisture provided by the open water areas and melting snow. Barry and Hare (1974) noted that local fogs and stratus clouds could occur even in the absence of cyclonic convergence since little uplift is necessary to saturate the air. Precipitation falls mainly as rain, except in the mountain areas. Most precipitation is related to cyclone passages, but orographic effects are also very important. The year-to-year variability of monthly and seasonal totals is very great and it is dependent on the frequency of passing depressions.

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