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Abstrakt

This study presents the results of dendrochronological and dendroclimatological research of Betula pubescens from four sites in northern Norway (Kvaløya Island, Tromsøya Island and Storelva Valley), which provided a 193-year chronology. Our results highlight the importance of the site selection in dendroclimatological studies. We demonstrated that activity of geomorphic processes connected with local topography could led to reduced strength of climatic signal embedded in tree-ring data. Negative pointer years, triggered mainly by unfavourable climatic conditions and insect outbreaks, were common for all site chronologies in 1945, 1955, 1965, 1975, 1986, 2004. However, some site-specific differences were also distinguished. Response function analysis confirmed that June, July and August temperatures were positively correlated with tree-ring widths. This climate-growth relationship was stable throughout the years 1925-2000. From summer temperature reconstruction back to AD 1820, two colder (c. 1835-1850 and 1890-1920) and two warmer (c. 1825-1835 and 1920-1940) periods were identified. The tree-ring record from the Tromsø Region, well correlated between series, sites and climate variables, is an important element of a large-scale reconstruction of pre-instrumental climate variation in the northeastern part of the Atlantic Ocean. Our dendroclimatic reconstruction corresponds well with other climate proxy data, like fluctuations of mountain glaciers in Scandinavia or sea ice extent.
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Abstrakt

Meteorological and biometeorological conditions during the warm seasons (June– September) of 1979–2008 are described for the Hornsund area, Spitsbergen. The measure− ments were taken at four sites: at Hornsund, at the Hans Glacier (at its equilibrium line and in the firn section) and at the summit of Fugleberget. The variation of meteorological and biometeorological conditions was analysed in relation to altitude, distance from the sea and the ground type. In warm seasons, the air temperature at Hornsund was 2.2 #2;C higher on aver− age than at the Hans Glacier (central section) and by 2.8 #2;C than at the Hans Glacier (firn sec− tion) and at Fugleberget. The average wind speed recorded at Hornsund was higher (0.6ms−1) than at the Hans Glacier and lower (0.9ms−1) than at Fugleberget. Four biometeorological in− dices were used: wind chill index (WCI), predicted insulation of clothing (Iclp), cooling power (H) and subjective temperature index (STI). The strongest thermal stimuli were ob− served on the Hans Glacier and in the upper mountain areas. The study has found a consider− able degree of spatial variation between the meteorological elements investigated and the biometeorological indices in the Hornsund area. The impact of atmospheric circulation on meteorological elements and biometeorological indices is also presented. The mildest bio− meteorological conditions of the warm season found at Hornsund were associated with air masses arriving from the southwest and west.
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