Visible progress has been observed recently in research concerning changes in the climate of the Northern Hemisphere, the Arctic included, and this is why the present update has drawn attention to major publications discussing this issue. Apart from the atmosphere, other elements of the Arctic climatic system are also being studied to a greater extent, mainly the ocean and the cryosphere. Researchers are paying particular attention to investigating the mechanisms determining the variability of climate in the Arctic in interannual, interdecadal, and century time-scales. Both anthropogenic and natural factors are being taken into consideration, with the latter still appearing to play a significant role in the variability of the climate of this region, especially in the case of short-term changes (the first two scales).
Various aspects of the variability of different components of the Arctic climatic system (trends, cycles) and the relations between them have been examined using longer and longer sets of data which characterise the components (both standard surface observations, including NCEP/NCAR and ECMWF Reanalyses have recently been made available, along with satellite data). In the case of research on the atmosphere, many researchers have looked for interrelations between the circulation of the atmosphere and other elements of the natural environment of the Arctic. Circulation variability indices, such as the North Atlantic Oscillation index (NAO), the North Pacific Index (NPI) and the recently introduced Arctic Oscillation (AO) are most often used for this purpose. Among the most recent works discussing these issues we should mention, among others, Maslanik et al. (1996), Serreze et al. (1997), Hurrell & van Loon (1997), Mysak & Venegas (1998), Thompson & Wallace (1998), Kwok & Rothrock (1999), Polyakov et al. (1999), Proshutinsky et al. (1999), Deser (2000), Dickson et al. (2000), Kwok (2000), Przybylak (2000a), Rigor et al. (2000), Skeie (2000), Wang & Ikeda (2000), Cohen et al. (2001), Haas & Eicken (2001), and Mysak (2001). Even without a detailed discussion of the results presented in those works, in order to underline the importance of the influence of circulation changes on the climate of the Arctic it is enough to quote one of the most important conclusions drawn by Rigor et al. (2000). They found that "...changes in surface air temperature over the Arctic Ocean are related to the Arctic Oscillation, which accounts for more than half of the surface air temperature trends over Alaska, Eurasia, and the eastern Arctic Ocean but less than half in the western Arctic Ocean." Some researchers have also tried to find the existing natural cycles in temporal series describing sea-ice cover and atmospheric circulation (Yi et al. 1999; Venegas & Mysak 2000). The variability of the climate of the Arctic and its driving factors were also examined using climatic models (e.g. Zhang et al 1998; Maslowski et al. 2000; Zhang & Hunke 2001).
Meteorological data from the Arctic have recently become more accessible, especially those from the Russian Arctic which had hardly been available up to now. Currently series of mean monthly T and monthly P totals from many stations from this area are available in a digital version (such as on the CD-ROM The Arctic Climatology Project, Arctic Meteorology and Climate Atlas, Version 1.0, 1 April 2000, or from the database of the Global
Historical Climatology Network (GHCN), Version 1 and 2 produced by the National Climatic Data Center/NOAA, the Office of Climatology Arizona State University, and the Carbon Dioxide Information Analysis Center/ORNL/DOE). However, the data series usually only cover the period up to around 1990. Daily data (until 1995) for a smaller number of stations have recently been made available by the All-Russian Research Institute of Hydrometeorological Information - World Data Centre B (http://www.meteo.ru/data). The Arctic and Antarctic Research Institute in St. Petersburg has also recently made available meteorological data collected during the operations of the North Pole drifting stations in the years 1937 and 1950-1991. These data are now available in digital version on the above CD-ROM, as well as on an earlier CD-ROM Arctic Ocean, Snow and Meteorological Observations from Drifting Stations 1937, 1950-1991, Version 1.0, 1996. As was mentioned in the previous sub-chapter, the results of these observations have been presented in numerous works, and they have also been used to create new databases (POLES and IABP/POLES). In the present update they were used to a limited extent.
The data from the Canadian and Norwegian Arctic are now also more easily available. They can be obtained directly from the Canadian Climate Centre (or from the Historical Canadian Climate Database Version 2 - http:/ /www.cccma.bc.ec.gc.ca/hccd/data developed by this Centre) and from the Norwegian Meteorological Institute. The most difficult and most expensive data to obtain are those from Greenland, though some have been made available in Monthly Climatic Data for the World (MCDW).
For the purposes of the present work, the series of meteorological data (monthly means/totals of T/P) presented in Chapter 3 have been updated for 1990s. For the Norwegian and Canadian Arctic they were obtained from the above sources, for Greenland and Alaska from the MCDW, and for the Russian Arctic they were taken from the database which was made available by World Data Center B and from MCDW. The list of stations which were used here to examine these issues has been supplemented in this update by a few stations from the area ofthe Russian and Canadian Arctic and Alaska. Due to closures of stations, the introduction of automatic stations, or the inaccessibility of data, some stations from the area of Greenland or the Russian Arctic have been excluded. For similar reasons, the data for the 1990s are not available for some of the stations (see Table 9.1). A list of the stations used in this update and their localisations is presented in Figure 9.1.
It is also worth mentioning that the data presently available are of a much higher quality. Great efforts have been made by the Canadian Climate Centre and Norwegian Meteorological Institute to obtain homogeneous data (both monthly and daily) (for details see e.g. Nordli et al. 1997; Vincent & Gullett 1999; Mekis & Hogg 1999; Tuomenvirta 2001).
Figure 9.1. Location of meteorological stations used.
Key: continuous thick line - the border of the Arctic after Atlas Arktiki (1985), dots - meteorological stations:
1 - Angmagssalik (height above sea level H = 35 m), 2 - Danmarkshavn (H =11 m), 3 - Ian Mayen (H = 10 m). 4 - Svalbard Lufthavn (H = 28 m). 5 - Björnöya (H = 15 m). 6 - Höpen (H = 6 m). 7 - Kanin Nos (H = 49). 8 - Naryan-Mar (H = 7 m). 9 - Polar GMO E.T. Krenkelya (H = 20 m), 10 - Mys Kamenny (H = 7 m), 11 - Ostrov Vize (H = 18 m), 12 - Ostrov Dikson (H = 20 m). 13 - GMO E.K. Fedorova (H = 13 m). 14 - Ostrov Kotelny (H = 10 m). 15 - Chokurdakh (H = 48 m). 16 - Ostrov Chetryrekhstolbovoy (H = 6 m). 17 - Mys Shmidta (H = 7 m). 18 - Ostrov Vrangel (H = 3 m). 19 - Nome (H = 11m), 20 - Kotzebue (H = 5 m). 21 - Barrow (H = 4 m). 22 - Sachs Harbour A (H = 88 mi. 23 - Mould Bay A (H = 15 m). 24 - Coppermine A (H = 24 m). 25 - Cambridge Bay (H = 27 m). 26 - Baker Lake A (H = 18 m). 27 - Resolute A (H = 67 m). 28 - Churchill A (H = 29 m). 29 - Eureka (H = 10 m). 30 - Coral Harbour A (H = 64 m). 31 - Hall Beach A (H = 8 m). 32 - Clyde A (H = 25 m). 33 - Iqaluit A (H = 34 m). 34 - Kuujjuaq (H = 37 m). 35 - Alert (H = 63 m). 36 - Egedesminde (H = 48 m). 37 - Godthab (H = 20 m). 38 - Akureyri (H = 27 m). 39 Tromsö (H = 10 m). 40 - Vardo (H = 15 m). 41 - Murmansk (H = 46 m); 42 - Arkhangelsk (H = 13 m). 43 - Khatanga (H = 24 m). 44 - Inuvik (H = 68). 45 - Fort Smith A (H = 203 m). 46 - Kuujjuarapik A (H = 10m).
In order to render the results presented here fully comparable with those presented earlier (mainly in Chapters 5 and 6), analagous research and calculation procedures have been used, along with similar graphic and cartographic representations of the results.
Detailed research into T tendencies in the Arctic in the periods from 1951 to 1990 (in the present book) and from 1951 to 1995 (Przybylak 2000a) revealed the predominance of negative trends, even though most of them were not statistically significant. Slight increases in T have been prevailing in the recently observed "second phase of contemporary warming" (after 1975). However, they are up to four times smaller for the areally averaged Arctic Tthan for the analogous series for the Northern Hemisphere (land + ocean). Such a situation occurred, for example, in the period 1976-1995. Thus, it may be assumed that, up to 1995, the impact of the greenhouse effect had been only slightly observable in the Arctic or, as is suggested in the present book and in the article by Przybylak (2000a), it had decreased significantly through the activity of sulphate aerosol and a set of natural factors.
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