Seasonal and Annual Means of T T and T

mm7 i7 max

The variability of Tin the Arctic has been examined using seasonal and annual means for 7.. The analysis also incorporates extreme temperatures (Tmax and Tmin), which up to the present have not been worked out for the whole of the . The publications available discuss their behaviour in small areas of the Arctic (Przybylak & Usowicz 1994). One of the aims of the analysis of and is to determine whether their variability in recent decades corre-

min max J

sponds to the variability of those temperatures in areas outside the polar regions, where the global warming observable at present is caused mainly by an increase in 7\n while Tmax values do not manifest significant changes (IPCC 1990, 1992; Karl"et al. 1991, 1993a).

5.1.1 Long-term and Extreme Means

Before discussing particular aspects of the variability of Tin the Arctic, it is worthwhile reviewing its mean spatial distribution in this area. A review of the literature shows that there are few publications in which information on this issue can be found. What is more, most of them make use of maps of the distribution of T in the Arctic after Prik (1959) (e.g. Vowinckel & Orvig 1970, Donina 1971 and Martyn 1985). More recent studies in this field include CIA (1978), Atlas Arktiki (1985), and Herman (1986). In most of those studies the spatial distribution of T is shown only for January and July. It is Prik (1959) who includes maps for other months as well (February, April, August and October). However, there is a lack of studies showing the distribution of T for the four seasons of the year commonly recognised in literature on climatology (December to February, March to May, June to August, and September to November) and mean annual T. For this reason, the present author has decided to plot the distribution of isotherms for the periods mentioned on the basis of the most recent data from 1951-1990 (Figures 5.1 and 5.2). As far as T extremes are concerned, no maps showing their spatial distribution in the area of the Arctic appear to be available in the literature. Thus, in all likelihood, the maps included here (Figures 5.2 and 5.3) are the only ones existing. They were charted for one year (Figure 5.2) and for two outlying seasons (Figure 5.3) on the basis of the data from the study period. The course of the isotherms should be treated as approximate, especially in the areas where there are few meteorological stations (or none at all), for instance, in the case of the Central Arctic. The general distribution of mean T (Figures 5.1 and 5.2) is similar to those published. Detailed comparison is not

Figure 5.1. The spatial distribution of mean seasonal Tt in the Arctic, 1951-1990.

Figure 5.2. The spatial distribution of mean annual Tmax, Tm.n, and T., in the Arctic, 1951-1990,

Figure 5.3. The spatial distribution of the mean winter and summer Tmm (left panels) and Tn (right panels) in the Arctic, 1951-1990.
Table 5.1. The course of selected climatic elements in the Arctic (1-35) and Subarctic (36-45) stations over the period 1951-1990

Mr.

Siaiion

Ti

1951-1960 Tmax Tmin P

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