Study Area

Up to the present, the majority of researchers have not adopted a unanimous criterion for delineating the southern border of the Arctic. As will be demonstrated in the chapters to follow, the lack of such a criterion has been the cause of misunderstandings when researchers have been formulating general conclusions regarding the temperature changes of the Arctic as a whole in recent decades.

The name "Arctic" is derived from the Greek word arktos (a bear). The Arctic encompasses the area under the Great Bear constellation and is notable for its unique environmental and daylight characteristics. The main qualities that ought to be mentioned in this respect include the considerable snow and ice cover in the region (in the form of glaciers, ice-sheets, and sea ice), and the occurrence of polar nights and days. That the Arctic has been largely unaffected by human activity is another characteristic distinguishing it from other regions. Yet in spite of the considerable physico-geographical distinction of the Arctic, determined mainly by the climate and the possibilities it creates for the development of nature, the delineation of its borders is not easy.

There are three main criteria which have traditionally been used to delineate the borders ofthe Arctic (Baird 1967; Pietrov 1971; Jahn 1977): astronomical, climatic, and botanical.

According to the astronomical criterion, the Arctic Circle constitutes the southern border of the Arctic. The Arctic delineated in this way encompasses a considerable number of regions that cannot be perceived as belonging to the real Arctic. Nevertheless, many researchers have applied this criterion for purely practical reasons, considering the Arctic to be the region lying above a particular parallel which runs either north or south of the Arctic Circle. For example, for the southern border of the Arctic some researchers have chosen the 60°N parallel (Walsh 1977, 1978; Yeserkepova et al. 1982; Aleksandrov & Subbotin 1985; Subbotin 1985; Jones 1995, personal communication), the 65°N parallel (Kelly & Jones 1981a-d, 1982; Jones 1985a; Alekseev & Svyashchennikov 1991), or the 70°N parallel (Dmitriev 1994). In each ofthe above cases, the regions delineated on the basis of such criteria differ considerably from the real area of the Arctic.

Out of the three above criteria used to delineate the Arctic border, the climatic criterion is the one most commonly adopted as the most exact and appropriate. The most popular of these methods is the isotherm of the warmest month (10°C), proposed for the first time in Supan's classification of climates, and popularised by Koppen. Other popular climatic methods include Vahl's method covering the temperatures of both the warmest and the coolest months. The pattern established by Vahl was later modified by Nordenskjold who adopted as the Arctic border the warmest month temperature value, amounting to 9°C, diminished by one-tenth of the coolest month temperature.

One can also use the rate ofthe heat balance, and in particular the radiation balance, to delineate the borders ofthe Arctic (Gavrilova 1963; Vowinckel & Orvig 1970); the criterion is that the radiation balance in this area cannot exceed The border delineated in this way lies close to the warmest-month isotherm 10°C and the so-called Nordenskjold line.

The inventor of the botanical method is O. Nordenskjold, who adopted the northern limit of tree growth as the Arctic border. A modification of this method was proposed by Hustich (1973) who distinguished the polar "species border" of coniferous trees.

All the above borders are concerned exclusively with land areas. In the 1960s, the sea border of the Arctic was perceived as the occurrence of Arctic low temperature waters of reduced salinity with an upper layer of up to 200 m in depth constituting at least a third of the volume. In the 1970s this criterion was changed. Lomniewski et al. (1979) write that "presently, the decisive criterion for delineating the border is the joining of marine regions in surface and deep-sea circulation with the Arctic Ocean, the exchange of waters, and the Arctic and sub-Arctic region balances" (p. 16).

Figure 1.1. Locations of study area and meteorological stations from which climatic data have been used in the present work. Borders of the Arctic and climatic regions are taken after Atlas Arktiki (1985).

Key. 1 - Arctic border; 2 - borders of the climatic regions; 3 - borders of the climatic sub-regions; 4 - meteorological stations from which monthly, seasonal and annual data were taken; 5 - meteorological stations from which daily data were also available. I, II, ..., VII - climatic regions; la, lb etc. - climatic sub-regions. Their names are given in the list of symbols provided at the start of the book.

Figure 1.1. Locations of study area and meteorological stations from which climatic data have been used in the present work. Borders of the Arctic and climatic regions are taken after Atlas Arktiki (1985).

Key. 1 - Arctic border; 2 - borders of the climatic regions; 3 - borders of the climatic sub-regions; 4 - meteorological stations from which monthly, seasonal and annual data were taken; 5 - meteorological stations from which daily data were also available. I, II, ..., VII - climatic regions; la, lb etc. - climatic sub-regions. Their names are given in the list of symbols provided at the start of the book.

In the present work, it has been acknowledged that this problem has been best solved in Atlas Arktiki (1985) in which, apart from the southern border of the Arctic, seven climatic regions have also been delineated (Figure 1.1). Moreover, subordinate units (climatic sub-regions) have been distinguished within the Atlantic, Canadian, and the Arctic Ocean regions. All these borders, the Arctic border included, have been delineated on the basis of the climatic criterion. In order to achieve this goal, multiannual averages of the rate of a number of meteorological elements have been used. The averages have been computed for the periods representing mainly the first half of the 20lh century.

In order to mark the seven particular climatic regions, the authors of the Atlas used Roman numerals (I, II, ..., VII) while climatic sub-regions have been described in a written form. In the present work, acronyms have been added to the Roman numerals in order to distinguish the sub-regions. The symbols for climatic regions and sub-regions have also been used in tables and figures to save space. However, in order to for the text to make more sense to the reader, a different and more extended system of marking the climatic regions and sub-regions has been introduced with Roman numerals being replaced with the initial letters of the climatic regions' names (see the list of symbols at the start of the book).

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