Daily temperature measurements from six meteorological stations along the coast and fjords of western Spitsbergen have been digitized and quality controlled in a Norwegian, Russian and Polish collaboration. Complete daily data series have been reconstructed back to 1948 for all of the stations. One of the station's monthly temperature series has previously been extended back to 1898 and is included in this study. The long-term series show large temperature variability on western Spitsbergen with colder periods in the 1910s and 1960s and warmer periods in the 1930s, 1950s and in the 21st century. The most recent years are the warmest ones in the instrumental records. There is a positive and statistically significant trend in the annual times series for all of the stations; however, the strongest warming is seen in winter and spring. For the period 1979Á2015, the linear trends range from 1.0 to 1.38C/decade for the annual series and from 2.0 to 2.38C/decade in winter. Threshold statistics demonstrate a decrease in the number of cold days per year and an increase in the number of warm days. A decreasing inter-annual variability is observed. In winter, spring and autumn, the stations in the northernmost areas of west Spitsbergen and in the innermost parts of Isfjorden are the coldest ones. In summer, however, the southernmost station is the coldest one. To access the supplementary material for this article, please see the supplementary files under Article Tools, online.

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The article describes an optical response of metastructure consisted of two optically coupled resonant subwavelength rectangular -profile diffraction gratings, between which a layer of optically transparent dielectric was placed. The features of optical resonance transmittance and reflectance for optical PT-symmetry mode was numerical investigated and some advantages of using optical PT-symmetry for resonance transmittance (reflectance) improving was demonstrated. The spectral characteristics of the metastructure change when the pumping level changes and when the system switches from the optical parity-time-symmetry mode to the broken parity-time-symmetry mode were analyzed too.

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This article examines the relationship between interannual changes in the sea ice extent and thickness in the Kara Sea with climate change in the region and with sea surface temperature in the tropical North Atlantic. The data from observations at meteorological stations, ERA5 reanalysis, and data on the sea ice from the AARI website for 1979–2021 were used. The growth of ice in winter is most influenced by air temperature and downward long-wave radiation. In summer, interannual changes in sea ice extent are closely related to air temperature. The remote influence of the sea surface temperature anomalies in the tropics of the North Atlantic on the summer (July–September) sea ice in the Kara Sea is discovered 33–35 months later. A significant correlation between climate and sea ice anomalies can serve as the basis for predicting up to four years ahead.

The article discusses the results of applying in Antarctica an original technique for estimating albedo from photogrammetric data and exposure parameters by an unmanned aerial vehicle (UAV). The complexities of the photogrammetric observations under extreme conditions are considered. Conclusions are drawn on ways to improve the recording equipment and the direction of improving the technique for calculating albedo values based on photogrammetric materials and metadata.

The article discusses the regional features of the Svalbard climate based on the data of regular meteorological observations obtained at Norwegian, Russian and Polish stations. Attention is paid to the spatial features of the multi-year regime of surface air temperature (SAT). Climatic norms (1961-1990, WMO recommendations) calculated from all meteorological stations, as well as long-term changes in the spatial gradients of the SAT and estimates of the range of annual fluctuations, revealed stations (area) with a “continental” and “marine” type of climate, as well as trends in spatial heterogeneities of the Svalbard climate. The rate of “modern” climate warming (1990-2016) was, on average, three times higher compared with the period after II World War (1948-2016). The continentality and abnormality of the climate are analyzed. Conclusions are formulated about a regular change in the spatial features of the climate (SAT) and the manifestation of its anomalous nature in different periods (1960-1970, 1988 and 2005-2014).

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