ALBERT

Description: Remote Sensing, Vol. 10, Pages 677: Microrelief Associated with Gas Emission Craters: Remote-Sensing and Field-Based Study Remote Sensing doi: 10.3390/rs10050677 Authors: Alexander Kizyakov Artem Khomutov Mikhail Zimin Rustam Khairullin Elena Babkina Yury Dvornikov Marina Leibman Formation of gas emission craters (GEC) is a new process in the permafrost zone, leading to considerable terrain changes. Yet their role in changing the relief is local, incomparable in the volume of the removed deposits to other destructive cryogenic processes. However, the relief-forming role of GECs is not limited to the appearance of the crater itself, but also results in positive and negative microforms as well. Negative microforms are rounded hollows, surrounded by piles of ejected or extruded deposits. Hypotheses related to the origin of these forms are put forward and supported by an analysis of multi-temporal satellite images, field observations and photographs of GECs. Remote sensing data specifically was used for interpretation of landform origin, measuring distances and density of material scattering, identifying scattered material through analysis of repeated imagery. Remote-sensing and field data reliably substantiate an impact nature of the hollows around GECs. It is found that scattering of frozen blocks at a distance of up to 293 m from a GEC is capable of creating an impact hollow. These data indicate the influence of GEC on the relief through the formation of a microrelief within a radius of 15–20 times the radius of the crater itself. Our study aims at the prediction of risk zones.

Description: Remote Sensing, Vol. 9, Pages 1023: Comparison of Gas Emission Crater Geomorphodynamics on Yamal and Gydan Peninsulas (Russia), Based on Repeat Very-High-Resolution Stereopairs Remote Sensing doi: 10.3390/rs9101023 Authors: Alexander Kizyakov Mikhail Zimin Anton Sonyushkin Yury Dvornikov Artem Khomutov Marina Leibman Gas Emission Craters (GEC) represent a new phenomenon in permafrost regions discovered in the north of West Siberia. In this study we use very-high-resolution Worldview satellite stereopairs and Resurs-P images to reveal and measure the geomorphic features that preceded and followed GEC formation on the Yamal and Gydan peninsulas. Analysis of DEMs allowed us to: (1) distinguish different terrain positions of the GEC, at the foot of a gentle slope (Yamal), and on an upper edge of a terrace slope; (2) notice that the formation of both Yamal and Gydan GECs were preceded by mound development; (3) measure a funnel-shaped upper part and a cylindrical lower part for each crater; (4) and measure the expansion and plan form modification of GECs. Although the general characteristics of both craters are similar, there are differences when comparing both key sites in detail. The height of the mound and diameter of the resulting GEC in Yamal exceeds that in Gydan; GEC-1 was surrounded by a well-developed parapet, while AntGEC did not show any considerable accumulative body. Thus, using very-high-resolution remote sensing data allowed us to discriminate geomorphic features and relief positions characteristic for GEC formation. GECs are a potential threat to commercial facilities in permafrost and indigenous settlements, especially because at present there is no statistically significant number of study objects to identify the local environmental conditions in which the formation of new GEC is possible.

Description: Remote Sensing, Vol. 10, Pages 167: Terrestrial CDOM in Lakes of Yamal Peninsula: Connection to Lake and Lake Catchment Properties Remote Sensing doi: 10.3390/rs10020167 Authors: Yury Dvornikov Marina Leibman Birgit Heim Annett Bartsch Ulrike Herzschuh Tatiana Skorospekhova Irina Fedorova Artem Khomutov Barbara Widhalm Anatoly Gubarkov Sebastian Rößler In this study, we analyze interactions in lake and lake catchment systems of a continuous permafrost area. We assessed colored dissolved organic matter (CDOM) absorption at 440 nm (a(440)CDOM) and absorption slope (S300–500) in lakes using field sampling and optical remote sensing data for an area of 350 km2 in Central Yamal, Siberia. Applying a CDOM algorithm (ratio of green and red band reflectance) for two high spatial resolution multispectral GeoEye-1 and Worldview-2 satellite images, we were able to extrapolate the a(λ)CDOM data from 18 lakes sampled in the field to 356 lakes in the study area (model R2 = 0.79). Values of a(440)CDOM in 356 lakes varied from 0.48 to 8.35 m−1 with a median of 1.43 m−1. This a(λ)CDOM dataset was used to relate lake CDOM to 17 lake and lake catchment parameters derived from optical and radar remote sensing data and from digital elevation model analysis in order to establish the parameters controlling CDOM in lakes on the Yamal Peninsula. Regression tree model and boosted regression tree analysis showed that the activity of cryogenic processes (thermocirques) in the lake shores and lake water level were the two most important controls, explaining 48.4% and 28.4% of lake CDOM, respectively (R2 = 0.61). Activation of thermocirques led to a large input of terrestrial organic matter and sediments from catchments and thawed permafrost to lakes (n = 15, mean a(440)CDOM = 5.3 m−1). Large lakes on the floodplain with a connection to Mordy-Yakha River received more CDOM (n = 7, mean a(440)CDOM = 3.8 m−1) compared to lakes located on higher terraces.

Description: The data set presents results from geospatial analyses of a region in Central Yamal, Western Siberia, which was affected by the construction of the Bovanenkovo railway line and by high Retrogressive Thaw Slumps (RTS) occurrence in consequence of the extremely warm and wet year 2012. A change detection was performed using high resolution optical satellite images from 2010 (GeoEye-1) and 2013 (QuickBird). The preprocessing of the satellite data (orthorectification and atmospheric correction) was performed by and is described in Dvornikov et al., 2016. The degree of disturbance change from 2010 and 2013 around the railway line was classified into three major disturbance levels - low, medium and high, based on the width of disturbance and magnitude of change over the course of three years. A kernel density raster file illustrates RTS distribution. The highest disturbance along the railway can be observed, where the RTS activity is the highest in 2013.

Description: The datasets present measurements of cDOM absorption of lakes located in Central Yamal regularly from the summer periods of 2011 on. The study region is in the central part of Yamal peninsula (Western Siberia, Russia) with the long-term research station Vaskiny Dachi. Vaskiny Dachi has been established in 1988 as permafrost monitoring site, since 1996 it is run by the Earth Cryosphere Institute (ECI), Siberian Branch of Russian Academy of Sciences and an established site for the international Global Terrestrial Network for Permafrost (GTN-P) program. Water samples were collected in calm weather conditions with bottle sampling from the upper 30 cm of water column close to the shore or in the center of lakes from boat. The coastal rim of several lakes on the high plains is affected by recent activation of thermocirques. The samples for CDOM were filtrated directly in the field after sampling. Filtrates for CDOM were prepared by filtrating through 0.7µm pore size glass fiber filters (Whatman) and were stored in cold and dark conditions to avoid the photodegradation of CDOM. CDOM filtrates have been measured after the expedition using the dual-beam Specord 200 laboratory spectrometer (Jena Analytik) at the Otto Schmidt Laboratory OSL, Arctic and Antarctic Research Institute, St. Petersburg, Russia. The OSL CDOM protocol (Heim and Roessler, 2016) prescribes 3 Absorbance (A) measurements per sample from UV to 750 nm against ultra-pure water. The absorption coefficient, a, is calculated by a = 2.303A/L, where L is the pathlength of the cuvette [m], and the factor 2.303 converts log10 to loge. The output of the calculation is a continuous spectrum of a. The CDOM a spectra are used to determine the exponential slope value for specific wavelength ranges, S by fitting the data between min and max wavelength to an exponential function. We provide CDOM absorption coefficients for the wavelengths 254, 260, 350, 375, 400, 412, 440, 443 nm [1/m] and Slope values for three different UV, VIS, wavelength ranges: 275 to 295 nm, 350 to 400 nm, 300 to 500 nm [1/nm]. All data sampling and processing were carried out by scientists from Earth Cryosphere Institute and Alfred Wegener Institute.