Laptev Sea Research Articles

Macroalgae of the high-Arctic Severnaya Zemlya Archipelago

Abstract Most of the archipelagos of the Russian Arctic are still extremely poorly studied. New data have been obtained using SCUBA diving and on-shore sampling during the“Open Ocean: Arctic Archipelagos – 2019. Severnaya Zemlya” expedition, which provided a significant update to scarce information on the seaweeds of the Severnaya Zemlya Archipelago. The list of macroalgae of the archipelago includes 48 species to date, belonging to Chlorophyta (17 species), Rhodophyta (18), and Phaeophyceae (13). Twenty-eight species are recorded for the first time in the study area; three species are new for the entire Russian Arctic. The taxonomic status of some observed species is discussed. For the first time, a wide distribution of kelps is described in the sub-tidal zone in the high-Arctic areas of the Siberian shelf, which is severely affected by ice disturbance and glacial processes. The highest population densities of the kelp communities have been observed near the Krasnoflotskie Islands (the Kara Sea) and in the Akhmatov and Mikoyan bays (the Laptev Sea). Further studies of the flora and vegetation of both the Severnaya Zemlya Archipelago shelf and other Arctic archipelagos are required.

Regional Features of the Arctic Sea Ice Area Changes in 2000–2019 versus 1979–1999 Periods

One of the most striking manifestations of ongoing climate change is a rapid shrinking of the Arctic sea ice area (SIA). An important feature of the observed SIA loss is a nonlinear rate of a decline with an accelerated decrease in the 2000–2019 period relative to a more gradual decline in 1979–1999. In this study, we perform a quantitative assessment and comparison of the spatial-temporal SIA changes during these two periods. It was found that winter Arctic SIA loss is primarily associated with changes in the Barents Sea, where the SIA decline in 2000–2019 has accelerated more than three-fold in comparison with 1979–1999. In summer and autumn, rates of SIA decline in 2000–2019 increased most strongly in the Kara, Beaufort Seas, the Northwestern Passage, and inner Arctic Ocean. The amplitude of the SIA seasonal cycle has also increased in 2000–2019 in comparison with the earlier period, with the largest changes in the inner Arctic Ocean, the Kara, Laptev, East Siberian and Beaufort Seas in summer and in the Barents Sea in winter. The results may reflect a transition to a new dynamic state in the recent two decades with the triggering of positive feedbacks in the Arctic climate system.

RESEARCH OF NAVIGATIONAL AND HYDROGRAPHIC CHARACTERISTICS OF FLAW POLYNYAS OF THE EASTERN SECTOR OF THE NORTHERN SEA ROUTE

The possibility of using the areas of flaw polynyas in the Eastern sector of the Northern Sea Route in planning and choosing the routes for navigation of transport ships is considered in the paper. It is noted that shipping in the Arctic seas is associated with an increased level of risk, shallow seas and difficult hydrometeorological conditions, and is also characterized by insufficient or completely absent hydrographic knowledge of the bottom topography. The main data characterizing the increase in the number of issued permits for ships navigation in the water area of the Northern Sea Route, and the percentage of ships depending on the ice class are given. It is noted that in the cold season, the main navigable straits of the Northern Sea Route are covered with fast ice. Due to circulation and under-ice currents, flaw polynyas, which can be used when planning navigation routes, are formed. The main flaw polynyas of the Eastern Sector of the Northern Sea Route are presented; data on their width, length and range of depths are provided. It is noted that the flaw polynyas of the East Siberian and Chukchi seas are deeper than the polynyas of the Laptev Sea. The ships classification depending on the draft is presented in the paper; an analysis of the characteristic routes for each category of ships is performed. An analysis of the data received from the automatic identification system of vessels has revealed that the choice of route is seasonal and directly depends on the ice conditions of the water area. The relevance of the topic is due to the need to increase the duration of navigation in the Eastern sector of the Northern Sea Route, in order to achieve targets for the volume of cargo transportation. This can be achieved by choosing the route of the transport vessel along the areas of ice polynyas, which are a strip of open water and young ice.

Nutrient and Silicon Isotope Dynamics in the Laptev Sea and Implications for Nutrient Availability in the Transpolar Drift

AbstractRealistic prediction of the near‐future response of Arctic Ocean primary productivity to ongoing warming and sea ice loss requires a mechanistic understanding of the processes controlling nutrient bioavailability. To evaluate continental nutrient inputs, biological utilization, and the influence of mixing and winter processes in the Laptev Sea, the major source region of the Transpolar Drift (TPD), we compare observed with preformed concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP), silicic acid (DSi), and silicon isotope compositions of DSi (δ30SiDSi) obtained for two summers (2013 and 2014) and one winter (2012). In summer, preformed nutrient concentrations persisted in the surface layer of the southeastern Laptev Sea, while diatom‐dominated utilization caused intense northward drawdown and a pronounced shift in δ30SiDSi from +0.91 to +3.82‰. The modeled Si isotope fractionation suggests that DSi in the northern Laptev Sea originated from the Lena River and was supplied during the spring freshet, while riverine DSi in the southeastern Laptev Sea was continuously supplied during the summer. Primary productivity fueled by river‐borne nutrients was enhanced by admixture of DIN‐ and DIP‐rich Atlantic‐sourced waters to the surface, either by convective mixing during the previous winter or by occasional storm‐induced stratification breakdowns in late summer. Substantial enrichments of DSi (+240%) and DIP (+90%) beneath the Lena River plume were caused by sea ice‐driven redistribution and remineralization. Predicted weaker stratification on the outer Laptev Shelf will enhance DSi utilization and removal through greater vertical DIN supply, which will limit DSi export and reduce diatom‐dominated primary productivity in the TPD.

Atmospheric CO2 and CH4 Fluctuations over the Continent-Sea Interface in the Yenisei River Sector of the Kara Sea

Observations of the atmospheric sources and sinks of carbon dioxide (CO2) and methane (CH4) in the pan-Arctic domain are extremely scarce, limiting our knowledge of carbon turnover in this climatically sensitive environment and the fate of the enormous carbon reservoirs conserved in the permafrost. Especially critical are the gaps in the high latitudes of Siberia, covered by the vast permafrost underlain tundra, where only several atmospheric monitoring sites are operational. This paper presents the first two years (September 2018–January 2021) of accurate continuous observations of atmospheric CO2 and CH4 dry mole fractions at the recently deployed tower-based measurement station “DIAMIS” (73.5068° N, 80.5198° E) located on the southwestern coast of the Taimyr Peninsula, Siberia, at the Gulf of the Yenisei River that opens to the Kara Sea (Arctic Ocean). In this paper, we summarized the scientific rationale of the site, examined the seasonal footprint of the station with an analysis of terrestrial vegetation and maritime sector contributing to the captured atmospheric signal, and illustrated temporal patterns of CO2 and CH4 for the daytime mixed atmospheric layer over the continent–sea interface. Along with the temporal variations reflecting a signal caused pan-Arctic and not very much influenced by the local processes, we analyzed the spatiotemporal distribution of the synoptic anomalies representing the atmospheric signatures of regional sources and sinks of CO2 and CH4 for the studied high-arctic Siberian domain of ~625 thousand km2, with nearly equal capturing the land surface (54%) and the ocean (46%) throughout the year. Both for CO2 and CH4, we have observed a sea–continent declining trend, presuming a larger depletion of trace gases in the maritime air masses compared to the continental domain. So far, over the Kara Sea, we have not detected any prominent signals of CH4 that might have indicated processes of subsea permafrost degradation and occurrence of cold seeps–still mainly observed in the eastern Arctic Seas—The Laptev Sea and the East-Siberian Sea.

Organic matter composition and greenhouse gas production of thawing subsea permafrost in the Laptev Sea

Subsea permafrost represents a large carbon pool that might be or become a significant greenhouse gas source. Scarcity of observational data causes large uncertainties. We here use five 21-56 m long subsea permafrost cores from the Laptev Sea to constrain organic carbon (OC) storage and sources, degradation state and potential greenhouse gas production upon thaw. Grain sizes, optically-stimulated luminescence and biomarkers suggest deposition of aeolian silt and fluvial sand over 160 000 years, with dominant fluvial/alluvial deposition of forest- and tundra-derived organic matter. We estimate an annual thaw rate of 1.3 ± 0.6 kg OC m−2 in subsea permafrost in the area, nine-fold exceeding organic carbon thaw rates for terrestrial permafrost. During 20-month incubations, CH4 and CO2 production averaged 1.7 nmol and 2.4 µmol g−1 OC d−1, providing a baseline to assess the contribution of subsea permafrost to the high CH4 fluxes and strong ocean acidification observed in the region.

Heavy mineral assemblages of the De Long Trough and southern Lomonosov Ridge glacigenic deposits: implications for the East Siberian Ice Sheet extent

Abstract. The Arctic's glacial history has classically been interpreted from marine records in terms of the fluctuations of the Eurasian and North American ice sheets. However, the extent and timing of the East Siberian Ice Sheet (ESIS) have remained uncertain. A recently discovered glacially scoured cross-shelf trough extending to the edge of the continental shelf north of the De Long Islands has provided additional evidence that glacial ice existed on parts of the East Siberian Sea (ESS) during previous glacial periods MIS 6 and 4. This study concentrates on defining the heavy mineral signature of glacigenic deposits from the East Siberian continental margin which were collected during the 2014 SWERUS-C3 expedition. The cores studied are 20-GC1 from the East Siberian shelf, 23-GC1 and 24-GC1 from the De Long Trough (DLT), and 29-GC1 from the southern Lomonosov Ridge (LR). Heavy mineral assemblages were used to identify prominent parent rocks in hinterland and other sediment source areas. The parent rock areas include major eastern Siberian geological provinces such as the Omolon massif, the Chukotka fold belt, the Verkhoyansk fold belt, and possibly the Okhotsk–Chukotka volcanic belt. The primary riverine sources for the ESS sediments are the Indigirka and Kolyma rivers, the material of which was glacially eroded and re-deposited in the DLT. The higher abundances of amphiboles in the heavy mineral assemblages may indicate ESS paleovalley of the Indigirka River as a major pathway of sediments, while the Kolyma River paleovalley pathway relates to a higher share of pyroxenes and epidote. The mineralogical signature in the DLT diamicts, consisting predominantly of amphiboles and pyroxenes with a minor content of garnet and epidote, shows clear delivery from the eastern part of the ESIS. Although the physical properties of the DLT glacial diamict closely resemble a pervasive diamict unit recovered from the southern LR, their source material is slightly different. The assemblages with elevated amphibole and garnet content, along with higher titanite and ilmenite content of the southern LR ice-rafted diamict, emphasise the Verkhoyansk fold belt as a possible primary source. The presence of glacial sediments and the recovered glacial–tectonic features on the East Siberian continental shelf and slope, along with the results from this heavy mineral analysis, imply that glacial ice not only grew out of the East Siberian shelf but also from the De Long Islands, and that there was also ice rafting related sediment transportation to the southern LR from westerly sources, such as the Laptev Sea.

Fluorescent signatures of autochthonous dissolved organic matter production in Siberian shelf seas

The East Siberian Sea is an area of high biogeochemical activity caused by multiple factors, such as an influence of river runoff, Atlantic, and Pacific waters, formation and melting of sea ice, and internal circulation. Extensive amounts of carbon are accumulated in sub-sea permafrost within the Arctic shelf in East Siberia. Thawing permafrost and resulting microbial decomposition of frozen carbon pool is a potential feedback process affected global climate dynamics. Several studies of dissolved organic carbon (DOC) distribution in the East Siberian Sea have demonstrated untypical for other Arctic shelf seas pronounced non-conservative DOC behavior. Using seawater samples from the 69th cruise of R/V Akademik Mstislav Keldysh conducted in the Laptev and East Siberian seas in September 2017, this study examines the distribution of fluorescent dissolved organic matter (FDOM) along the shelf-crossing transects including the areas affected by the Khatanga, Lena, Indigirka, and Kolyma river runoff. The set of 137 excitation-emission matrices (EEMs), analyzed with Parallel Factor analysis (PARAFAC), was described by a 4-component model demonstrating Tucker’s congruence coefficient above the 0.95 threshold. Spectral characteristics of the resulting components allowed identifying them as well-known humic-like A and C, protein-like B/T, and marine humic-like M fluorophores. Component C1 (A fluorophore) showed a good correlation with salinity for different river plume influenced regions. As well as chromophoric DOM (CDOM) absorption, it can be used as marker of input of terrestrial DOM to the Arctic Ocean. A distinctive feature of the East Siberian Sea shelf waters in comparison with the Laptev Sea is the higher content of the C2 and C4 components, exhibiting protein-like and marine humic-like fluorescence. Component C3 (C fluorophore) which is usually identified as terrestrial-derived material, was found to be produced locally on the East Siberian Sea shelf and in the continental slope region of the Khatanga transect. Destruction of dead algae cells, production of marine biota and dissolved organic matter (DOM) reworking are considered as possible autochthonous FDOM sources in the Siberian shelf seas.

Cenozoic deposits of western Kotel’nyi Island (New Siberian Islands): key insights into the tectonic evolution of the Laptev Sea

ABSTRACT The Arctic sedimentary basins are still poorly studied in comparison with other regions. The lack of deep wells across the eastern Russian Arctic has resulted in numerous contrasting geodynamic models for the geological evolution and age of sedimentary successions within this frontier region, where a modern mid-ocean ridge breaks through the continental crust in the Laptev Sea. The only onshore evidence of rifting processes is a number of small graben-like depressions exposed on the New Siberian Islands and along the Laptev Sea coast. We present U-Pb detrital zircon provenance and palynology study results of the Cenozoic sedimentary rocks filling graben-like depressions across western Kotel’nyi Island. Palynological data indicate that these sedimentary rocks are Early Eocene to Pleistocene in age. Based on U-Pb detrital zircon dating, Early Eocene and Late Oligocene clastic sediments were sourced from underlying deformed Palaeozoic rocks as well as by reworking of Upper Mesozoic rocks outcropping elsewhere on Kotel’nyi Island, which bear Siberian signature. Plio-Pleistocene clastic sediments were not derived from the erosion of deformed Palaeozoic rocks, suggesting the cessation of active uplift by this time and the development of a regional peneplain. Therefore, by extrapolating our onshore observations to the neighbouring offshore, we propose that graben structures imaged by seismic profiles along the eastern flank of the Laptev Rift System are likely to host Eocene and Oligocene sediments. Thus, it implies the Cenozoic extension led to formation of grabens on- and offshore in the eastern portion of Laptev Sea as early as Eocene. Further studies are necessary to evaluate the age of graben-related basins in the central and western part of the Laptev Sea.

Improving the CFSv2 prediction of the Indian Ocean Dipole based on a physical‐empirical model and a deep‐learning approach

AbstractDespite significant advances in seasonal climate forecasts, the reliability of both dynamical and empirical models for the Indian Ocean Dipole (IOD) prediction is still limited to a lead time of one season or less. In this study, the skill of the NCEP Climate Forecast System version 2 (CFSv2) for the IOD prediction during the period 1982–2014 is evaluated. The results indicate that the model performance for the IOD prediction is the worst in spring among the four seasons, which is manifested in the fact that a skilful prediction of spring IOD event is limited to a lead time of only about 1–2 months. To improve the forecast of spring IOD events, a physical‐empirical (PE) model and a convolutional neural network (CNN) model are established in the present study. The IOD in April–May–June (AMJ) is taken as the predictand, and the CFSv2‐predicted sea surface height (SSH) in AMJ and the observed Laptev sea ice in the preceding December are used as the two predictors. The original CFSv2‐predicted IOD time series has an insignificant correlation with the observed IOD time series with a temporal correlation coefficient (TCC) of 0.03; the PE model (CNN model) can largely improve the IOD prediction with a TCC of 0.74 (0.77) between the PE‐model‐predicted (CNN‐model‐predicted) IOD and the observed IOD during AMJ. Thus, the PE model and the CNN model developed in the present study can be applied to improve the IOD predictions from numerical models in the future.

The Structural–Formational Zoning of the Laptev Sea Shelf (Eastern Arctic)

The Structural–Formational Zoning of the Laptev Sea Shelf (Eastern Arctic)

An analysis of the characteristics of precipitation in the Northeast passage and its relationship with sea ice

Precipitation is an important part of the atmospheric circulation in the Arctic and is of great significance to the energy budget and hydrological characteristics of the Arctic region. The distribution of precipitation affects the exchange of energy, which then affects the Arctic sea ice indirectly. Arctic precipitation impacts the sea surface albedo, which leads to changes in the sea ice concentration (SIC) and the energy exchange between the sea, ice, and air. In this study, GPM IMERG precipitation data, which have a spatial resolution of 0.1°, were used to analyze the characteristics of precipitation in the Northeast Passage (NEP) from May to December during the period 2011–2020. This analysis of the amount of precipitation and its distribution were performed for the Barents Sea, Kara Sea, Laptev Sea, and East Siberian Sea. The relationship between precipitation and sea ice was also explored. The results show that, during the study period, the average precipitation over the Barents Sea from May to December was 57–561 mm/year and that this area had the highest precipitation in the NEP. For the Kara Sea, the average precipitation for May to December was 50–386 mm/year and for the East Siberian Sea and the Laptev Sea it was 48–303 mm/year and 53–177 mm/year, respectively. For the NEP as a whole, September was found to be the month with the highest average precipitation. An analysis of the correlation between the precipitation and the SIC gave a correlation coefficient of −0.792 for the study period and showed that there is a 15-day delay between the precipitation increase and the decrease in SIC. The analysis of the precipitation data in these areas thus showed that precipitation is related to SIC and is of great importance to understanding and predicting the navigable capacity of the NEP.

Suspended Matter and Hydrocarbons Fluxes in the Kara and Laptev Seas

The distribution of suspended particulate matter (SPM) by filtration and the magnitude of its fluxs using sediment traps in the Kara and Laptev Seas (cruise 72 of the R/V Akademik Mstislav Keldysh, August–September 2018) was studied. The composition of the SPM was determined by the material composition using an electron microscope, the organic component (Corg and hydrocarbons) and the inorganic component (amorphous silica and calcium carbonate). It was found that the SPM content in surface waters varied from 0.2 to 5.9 mg/L (on average 0.90 mg/L) with a maximum in the Blagopolychia Bay and aliphatic hydrocarbons from 10 to 49 µg/L (average 22 µg/L) with a maximum in the area of the removals of the river Ob. The SPM flux decreased from the surface to the near-bottom horizon only into the Blagopolychia Bay (from 13,127 to 11,900 mg/m2/day), but in most samples the flux increased in the near-bottom horizon with a maximum of 6920 mg/m2/day in the Ob’s discharge water area and correlated with the maximum of the Corg flux 695 mg/m2/day. In the composition of SPM, as well as in organic compounds, including hydrocarbons, allochthonous basically prevailed over autochthonous.

CALIBRATION FREE LIBS FOR THE DETERMINATION OF Mn/Fe RATIO IN FERROMANGANESE NODULES WITH PORTABLE DIODE PUMPED SOLID STATE LASER

The Mn/Fe ratio, which serves as a marker of the content of rare earth elements and the platinum group elements in ferromanganese nodules, was determined in samples taken during expeditions to the Kara Sea and the Laptev Sea, as well as in a set of certified reference materials (ОOPE 601—604). The analysis was carried out by calibration-free laser-induced breakdown spectroscopy, based on the use of plasma parameters and intensities of analytical lines of manganese and iron (Mn I 542.04 nm and Fe I 539.71 nm). Boltzmann plot was used to determine the plasma temperature and Stark broadening of Fe I line 538.34 nm was used to determine electron density. We have shown the possibility of determining the Mn/Fe ratio in range
 from 0.2 to 4.2 in ferromanganese nodules of various geographic origin. A high coefficient of linear determination (R2 = 0.938) and proportionality between the results of calibration-free laser-induced breakdown spectroscopy and inductively coupled plasma atomic emission spectrometry (1:0.99) were achieved.

A statistical downscaling prediction model for winter temperature over Xinjiang based on the CFSv2 and sea ice forcing

AbstractBased on a year‐to‐year increment approach, a statistical downscaling model is developed for winter temperature prediction over Xinjiang of northwest China by using the predicted 200‐hPa westerly wind in winter over the Ural Mountains from the Climate Forecast System version 2 (CFSv2) as well as the observed sea ice over the Barents Sea–Laptev Sea in the preceding September. The statistical downscaling hindcasts on the 1983–2018 winter temperature over Xinjiang show that the statistical downscaling method has significantly improved the prediction capability compared with the original CFSv2. Specifically, the temporal correlation coefficients increase from negative to positive in most of Xinjiang, with the values passing the significance test at 90% confidence level at 81% of the stations. The regional averaged root‐mean‐square error reduces by more than 20%. In addition, the anomaly correlation coefficient increases from 0.08 to 0.26, passing the significance test at 95% confidence level. For two typical cases of the extreme cold winter in 2011 and the extreme warm winter in 2016, the spatial distribution characteristics of temperature anomaly are well reproduced, which are generally consistent with the observations. Overall, the statistical downscaling model based on the year‐to‐year increment strategy is a relatively effective method for predicting the winter temperature in Xinjiang.

Evident differences of haze days between December and January in north China and possible relationships with preceding climate factors

AbstractAir pollution of fine particulate matter (PM2.5) is severe in winter and causes vast premature deaths in north China. Many previous studies have concerned winter‐mean haze conditions and identified some useful climate factors. However, obvious differences in the number of haze days also existed between December and January (HDJ‐D) that lacked of understandings. The HDJ‐D maximum was 6.6 days, which occurred between December 2005 and January 2006, accounting for more than 45% of the monthly mean number of haze days in these 2 months. Differences of large‐scale atmospheric circulations were distributed like a Rossby wave pattern in mid‐troposphere, with centres in the west of Europe (+), the north to the Caspian Sea (−) and north China (+). Associated meteorological conditions in north China resulted in more adverse ventilation conditions and stronger chemical productions, and thus larger number of haze days in January than in December. In addition, significant relationships between HDJ‐D and three preceding climate factors during 1979–2018 were also revealed, including August–September–October sea ice over the Laptev Sea and the north of the Kara Sea (correlation coefficient = −0.53), November snow depth in eastern Europe and western Siberia (correlation coefficient = −0.44) and sea surface temperature over the Mid‐Atlantic Ridge (correlation coefficient = −0.48). Abundant analyses, basing on the observation data, large‐ensemble climate simulations and atmospheric chemical simulations, all reproduced the influences of each climate factor on large‐scale atmospheric circulations and local meteorological conditions associated with HDJ‐D changes.

Morphological variability and diagnostics of two sculpins Icelus bicornis and I. spatula (Cottiformes: Cottidae) from the Arctic

The morphological variability of Icelus spatula Gilbert et Burke, 1912 and I. bicornis Reinhardt, 1840 was studied in order to clarify the diagnostic characters of these poorly studied fishes. Allometry, geographic variability and sexual dimorphism of species were evaluated by statistical methods based on 24 counts and 30 morphometric indices. Samples from 5 Arctic regions were studied: southwestern Greenland, Spitsbergen, Barents Sea, Laptev and East Siberian seas. An analysis of the variability of diagnostic characters showed that the following can be used to identify species with high certainty: 1) the shape of the urogenital papilla (males); 2) the presence/absence of spinules on the lower-posterior margin of scales of the lateral line below the pore of the canal and the degree of development of spinules on the dorsal margin of these scales; 3) the presence of scales at the base of the caudal fin; 4) presence/absence of bony granules on the skin between the lateral line and dorsal row of scales. Other characters (the number of scales in the lateral line and in rows on the body behind the base of the pectoral fin, the length of the nuchal spines) are more variable. No clinal changes in meristic characters were found over the studied areas of ranges of the two species. Greenland population of I. bicornis differs markedly from the samples from the Barents and Laptev seas, which suggests the possibility of the existence of groups of subspecies rank in these waters. An updated key for identification of juveniles, females and males of I. bicornis and I. spatula is provided.

Warm and moist air intrusions into the winter Arctic: a Lagrangian view on the near-surface energy budgets

Abstract. In this study, warm and moist air intrusions (WaMAIs) over the Arctic Ocean sectors of Barents Sea, Kara Sea, Laptev Sea, East Siberian Sea, Chukchi Sea, and Beaufort Sea in 40 recent winters (from 1979 to 2018) are identified from the ERA5 reanalysis using both Eulerian and Lagrangian views. The analysis shows that WaMAIs, fueled by Arctic blocking, cause a relative surface warming and hence a sea-ice reduction by exerting positive anomalies of net thermal irradiances and turbulent fluxes on the surface. Over Arctic Ocean sectors with land-locked sea ice in winter, such as Laptev Sea, East Siberian Sea, Chukchi Sea, and Beaufort Sea, the total surface energy-budget is dominated by net thermal irradiance. From a Lagrangian perspective, total water path (TWP) increases linearly with the downstream distance from the sea-ice edge over the completely ice-covered sectors, inducing almost linearly increasing net thermal irradiance and total surface energy-budget. However, over the Barents Sea, with an open ocean to the south, total net surface energy-budget is dominated by the surface turbulent flux. With the energy in the warm-and-moist air continuously transported to the surface, net surface turbulent flux gradually decreases with distance, especially within the first 2∘ north of the ice edge, inducing a decreasing but still positive total surface energy-budget. The boundary-layer energy-budget patterns over the Barents Sea can be categorized into three classes: radiation-dominated, turbulence-dominated, and turbulence-dominated with cold dome, comprising about 52 %, 40 %, and 8 % of all WaMAIs, respectively. Statistically, turbulence-dominated cases with or without cold dome occur along with 1 order of magnitude larger large-scale subsidence than the radiation-dominated cases. For the turbulence-dominated category, larger turbulent fluxes are exerted to the surface, probably because of stronger wind shear. In radiation-dominated WaMAIs, stratocumulus develops more strongly and triggers intensive cloud-top radiative cooling and related buoyant mixing that extends from cloud top to the surface, inducing a thicker well-mixed layer under the cloud. With the existence of cold dome, fewer liquid water clouds were formed, and less or even negative turbulent fluxes could reach the surface.

Prospects of hydrocarbon exploration in the Laptev sea basin

Background. The geological structure of the Laptev Sea basin is characterized by a rift nature, thus providing no favorable conditions for the presence of hydrocarbon accumulations. However, the lack of seismic information and the absence of well drilling indicate an incomplete stage of the basin exploration.Aim. To analyze the results of geological modeling based on structural mapping and to identify promising areas of hydrocarbon exploration. A geological hydrocarbon study of the Laptev Sea basin was carried out in order to recommend areas for licensing, as well as to identify exploration drilling sites and estimate the total initial prospective geological resources according to the conducted numerical basin modeling. To design sedimentation models and predict reservoir properties in the Laptev Sea basin.Materials and methods. The analysis was based on the data retrieved from production reports for individual large objects in the water area. A model developed by Equinor specialists was used for the basin analysis. The results of hydrocarbon system modeling, the prediction of hydrocarbon saturation obtained from sections of two sample profiles while structural mapping of the basement and top of Oligocene-Miocene sediments were used.Results. Prospective areas of accumulation of hydrocarbons and their confinement were determined. The probability of hydrocarbons in non-anticlinal traps was estimated. Priority areas of hydrocarbon exploration within the unallocated subsoil area were identified. Recommendations for further geological exploration across the license area were formulated.Conclusion. Further exploration of the Yuzhno-Laptevomorsky promising area is recommended by means of analyzing the available data, processing of new geophysical data, updating the geological model and designing 3D seismic surveys within the identified promising areas. In addition, 2D seismic surveys at the regional level should be carried out to define the sedimentary boundaries of the Eastern Artic water area.

Mammoth Fauna Remains From Late Pleistocene Deposits of the Dmitry Laptev Strait South Coast (Northern Yakutia, Russia)

The Yedoma Ice Complex in northern Yakutia provides perfect preservation conditions for frozen remains of vertebrate animals. Even complete mummified specimens of the late Pleistocene Beringian Mammoth fauna such as woolly mammoth, woolly rhinoceros, horse, and bison are occasionally found in permafrost deposits across eastern Siberia, i.e., in West Beringia, although bones are much more commonly found. The present study characterizes mammal bones from late Pleistocene and Holocene permafrost deposits exposed on the Oyogos Yar coast, part of the southern shore of the Dmitry Laptev Strait that connects the Laptev and East Siberian seas. The study applies a method to characterize fossil bone samples by the location of their discovery and by the accuracy of their relation to a depositional horizon. We analyzed a total of 38 finite radiocarbon ages of bone material from mammoth, horse, and musk ox, spanning from about 48.8 to 4.5 ka BP and including both our own data and data from the literature, in addition to previous publications that reported numerous bones with infinite ages from the Oyogos Yar coast. The distribution of bones and tooth along the coastal permafrost exposure is not uniform; it depends upon whether the material was found in situ, on thermo-terraces, or on the shore. The overall bone collection consists of 13 species of which Mammuthus primigenius (woolly mammoth, 41%), Bison priscus (bison, 19%), Equus ex gr., caballus (horse, 19%), and Rangifer tarandus (reindeer, 16%) predominate. The fossil bone species distribution is similar to those of other prominent Yedoma outcrops in the region, i.e., on Bykovsky Peninsula and on Bol’shoy Lyakhovsky Island. Correlation analysis shows that the Oyogos Yar bone sampling sites of different geomorphological settings are similar to each other but not to all sampling sites within the other two locations on Bykovsky Peninsula and on Bol’shoy Lykahovsky Island. High similarities in terms of correlation coefficients between specific sampling sites are often not represented in the cluster analysis.