Spatial differentiation of temperature and relative humidity of air on western coast of Spitsbergen in 1979—1983 is presented. Applying the author's classification of types of atmospheric circulation in the studied area, its influence on distribution of these elements is shown. Air temperature in the area is related more to the degree of climate continentality than to its latitude. The lowest mean 5—year temperatures were calculated for stations with highest degrees of thermic continentality (Svea Gruber and Svalbard Lufthavn). The highest thermic differentiation occurs from November to March (1 —4°C) and the lowest in May—June and August—October (0.0— 1.5°C). It is opposite if relative humidity is concerned: the highest differences occur in summer (10—15%) and the lowest in winter (0—9%). Influence of atmospheric circulation on air temperature is larger during a polar night than a polar day. Again, it is opposite in the case of relative humidity. In both analyzed seasons the highest thermic differentiation occurred at the circulation type Ca. However, it was the lowest during a polar night at advection of air from northern and southern sectors, and during a polar day at advection from a northern sector and at the type Cc.

The paper presents a spatial distribution of changes of air temperature (T) in the Arctic. Estimates of their spatial relations in the study region were based on a correlation analysis. T in the Arctic is most strongly correlated spatially in winter and spring, and least in summer. The radius of extent of statistically significant correlation coefficients of changes of T at the stations Svalbard Lufthavn, Ostrov Kotelny and Resolute A is equal to 2000-2500 km in winter and 1500-2000 km in summer. An attempt was done to delimit the regions of consistent occurrence of the anomalies T with respect to the signs and magnitudes, as well as of the regions with the most coherent T. The Wroclaw dendrite method was used to solve this problem. Relations of the mean areał T of the climatic regions and of the Arctic as a whole, with the northern hemisphere of temperature and selected climatic factors are presented.

The paper describes climatic conditions of the north-western part of Oscar II Land (Spitsbergen) based on meteorological data from 1975 to 2000, which were taken from Ny Ĺlesund and Kaffiöyra-Heggodden stations. The changes in annual courses of main climatic elements are investigated. However, the authors focused mainly on the analysis of summer climate, because most of the field work is conducted at this time of the year. Aside from the standard climatic analysis, the influence of atmospheric circulation on selected meteorological elements was also investigated. The climate of the north-western part of Oscar II Land was compared with the climates of the remaining areas of the western coast of Spitsbergen . It was found that the climate of the studied area differs considerably from the climate of the central-inner and southern parts of the western coast of Spitsbergen (areas represented by the Svalbard Lufthavn and Hornsund stations respectively). The differences in climatic elements, however, are not stable throughout the year and in particular seasons and months can even change signs. Thus, any generalisation of results obtained based on seasonal data is inadmissible. It was also found that the wind conditions of the Kaffiöyra region are more representative of the north-western part of Oscar II Land than are the wind conditions of the Ny Ĺlesund region.

Height, frequency and spatial differentiation of atmospheric precipitation of the summer season for the period 1975-1982 are presented. Results of the respective investigations are compared with atmospheric precipitation in other areas of the western coast of Spitsbergen.

Temperature and precipitation conditions in the Kaffiøyra region in the summer season (21 July-31 August) for the period from 1975-2014 are described based on data collected during 22 expeditions, in which meteorological measurements were carried out, and complete data series combining both original and reconstructed data. The latter ones were obtained using data from the Ny Ålesund meteorological station, which are strongly correlated with data from the Kaffiøyra region. Seasonal statistics presented for temperature and precipitation based on these two sets of data reveal only slight changes. Summer temperatures in the Kaffiøyra region in the studied period (1975-2014) showed statistically significant strong upward trends, while precipitation totals revealed a downward trend, but not statistically significant. In the studied area, based on 40-years of data, it was demonstrated that the near-surface lapse rates of summer air temperature are slightly lower in glaciated (0.58°C/100 m) than in non-glaciated areas (0.67°C/100 m). Anticyclonic/cyclonic circulation types significantly increase/decrease air temperature on the Waldemar Glacier, while their impact on precipitation is markedly smaller. In summer, close correlations were observed between air temperature and such glacier characteristics as the mass balance and the location of the equilibrium line, while precipitation does not have a great influence on them.

This paper provides an overview of the results of research on changes in ground temperature down to 50 cm depth, on the Kaffiøyra Plain, Spitsbergen in the summer seasons. To achieve this, measurement data were analysed from three different ecotopes (CALM Site P2A, P2B and P2C) – a beach, a moraine and tundra – collected during 22 polar expeditions between 1975 and 2014. To ensure comparability, data sets for the common period from 21 July to 31 August (referred to as the “summer season” further in the text) were analysed. The greatest influence on temperature across the investigated ground layers comes from air temperature (correlation coefficients ranging from 0.61 to 0.84). For the purpose of the analysis of the changes in ground temperature in the years 1975–2014, missing data for certain summer seasons were reconstructed on the basis of similar data from a meteorological station at Ny-Ålesund. The ground temperature at the Beach site demonstrated a statistically−significant growing trend: at depths from 1 to 10 cm the temperature increased by 0.27–0.28 ° C per decade, and from 20 to 50 cm by as much as 0.30 ° C per decade. On the Kaffiøyra Plain, the North Atlantic Oscillation (NAO) has a greater influence on the ground an d air temperature than the Arctic Oscillation (AO).

This article analyses the conditions affecting the incoming global solar radiation in Hornsund (Spitsbergen) in spring of 2015. Incoming solar radiation turned out to be average for the season under analysis, as compared with longer-term data. The clearness index (KT) was 0.46, and was mainly determined by the extent of cloudiness. As a result of differences in the length of day, sunshine duration in May was greater than in April. Incoming solar radiation to the earth's surface is also affected by the atmospheric optical properties. The average value of aerosol optical depth (AOD) at 500 nm in Hornsund in spring of 2015 was 0.087. In the analysed period, increased values of AOD at 500 nm (up to 0.143) were observed, although these are not record values. Over April and May, the greatest part of optical depth was comprised of anthropogenic aerosols (41%), followed by marine aerosols (26%), desert dust (21%) and biomass-burning aerosols (12%). This indicates the significant role of the anthropogenic factor in the climatic conditions of Spitsbergen.

Unique and independent historical observations, carried out in the central Arctic during the early twentieth century warming (ETCW) period, were used to evaluate the older (20CRv2) and newer (20CRv2c) versions of the 20th Century Reanalysis and the HIRHAM5 regional climate model. The latter can reduce several biases compared to its forcing data set (20CRv2) probably due to higher horizontal resolution and a more realistic cloud parameterization. However, low-level temperature and near-surface specific humidity agree best between 20CRv2c and the surface-based observations. This better performance results from more realistic lower boundary conditions for sea ice concentration and sea surface temperature, but it is limited mainly to polar night. Although sea level pressures are very similar, the vertical stratification and baroclinicity change in the transition from 20CRv2 to 20CRv2c. Compared to observed temperature profiles, the systematic cold bias above 400 hPa remains almost unchanged indicating an incorrect coupling between the planetary boundary layer and free troposphere. In addition to surface pressures, it is therefore recommended to assimilate available vertical profiles of temperature, humidity and wind speed. This might also reduce the large biases in 10 m wind speed, but the reliability of the sea ice data remains a great unknown.