Entire Arctic Region Research Articles

Statistical appraisal of geothermal heat flow observations in the Arctic

Abstract. Geothermal heat flow is an important boundary condition for ice sheets, affecting, for example, basal melt rates, but for ice-covered regions, we only have sparse heat flow observations with partly high uncertainty of up to 30 m W m−2. In this study, we first investigate the agreement between such pointwise heat flow observations and solid Earth models, applying a 1D steady-state approach to perform a statistical analysis for the entire Arctic region. We find that most of the continental heat flow observations have a high reliability and agreement to solid Earth models, except a few data points, such as, for example, the NGRIP (North Greenland Ice Core Project) point in central Greenland. For further testing, we perform a conditional simulation with focus on Greenland in which the local characteristics of heat flow structures can be considered. Simple kriging shows that including or excluding the less reliable NGRIP point has a large influence on the surrounding heat flow. The geostatistical analysis with the conditional simulation supports the assumption that NGRIP might not only be problematic for representing a regional feature but likely is an outlier. Basal melt estimates show that such a local spot of high heat flow results in local high basal melt rates but leads to less variation than existing geophysical models.

Self-Attention Convolutional Long Short-Term Memory for Short-Term Arctic Sea Ice Motion Prediction Using Advanced Microwave Scanning Radiometer Earth Observing System 36.5 GHz Data

Over the past four decades, Arctic sea ice coverage has steadily declined. This loss of sea ice has amplified solar radiation and heat absorption from the ocean, exacerbating both polar ice loss and global warming. It has also accelerated changes in sea ice movement, posing safety risks for ship navigation. In recent years, numerical prediction models have dominated the field of sea ice movement prediction. However, these models often rely on extensive data sources, which can be limited in specific time periods or regions, reducing their applicability. This study introduces a novel approach for predicting Arctic sea ice motion within a 10-day window. We employ a Self-Attention ConvLSTM deep learning network based on single-source data, specifically optical flow derived from the Advanced Microwave Scanning Radiometer Earth Observing System 36.5 GHz data, covering the entire Arctic region. Upon verification, our method shows a reduction of 0.80 to 1.18 km in average mean absolute error over a 10-day period when compared to ConvLSTM, demonstrating its improved ability to capture the spatiotemporal correlation of sea ice motion vector fields and provide accurate predictions.

Variability in terrestrial characteristics and erosion rates on the Alaskan Beaufort Sea coast

Arctic coastal environments are eroding and rapidly changing. A lack of pan-Arctic observations limits our ability to understand controls on coastal erosion rates across the entire Arctic region. Here, we capitalize on an abundance of geospatial and remotely sensed data, in addition to model output, from the North Slope of Alaska to identify relationships between historical erosion rates and landscape characteristics to guide future modeling and observational efforts across the Arctic. Using existing datasets from the Alaska Beaufort Sea coast and a hierarchical clustering algorithm, we developed a set of 16 coastal typologies that captures the defining characteristics of environments susceptible to coastal erosion. Relationships between landscape characteristics and historical erosion rates show that no single variable alone is a good predictor of erosion rates. Variability in erosion rate decreases with increasing coastal elevation, but erosion rate magnitudes are highest for intermediate elevations. Areas along the Alaskan Beaufort Sea coast (ABSC) protected by barrier islands showed a three times lower erosion rate on average, suggesting that barrier islands are critical to maintaining mainland shore position. Finally, typologies with the highest erosion rates are not broadly representative of the ABSC and are generally associated with low elevation, north- to northeast-facing shorelines, a peaty pebbly silty lithology, and glaciomarine deposits with high ice content. All else being equal, warmer permafrost is also associated with higher erosion rates, suggesting that warming permafrost temperatures may contribute to higher future erosion rates on permafrost coasts. The suite of typologies can be used to guide future modeling and observational efforts by quantifying the distribution of coastlines with specific landscape characteristics and erosion rates.

Russian Universities as Actors of Arctic Science Diplomacy

Abstract. This article examines the role of Russian universities in emerging and further developing Arctic science diplomacy (ASD). According to authors, in the current geopolitical conditions Russian universities are significant ASD actors which perform a number of important functions for the organization of international scientific cooperation with foreign countries and making a positive image of Russia in the world. The paper uses a systemic approach to identify Russian universities’ contribution to the ASD development through various mechanisms: joint research projects and publications with foreign partners, the organization of international events on the Arctic issues and participation in prestigious international conferences on the Arctic research area, joint polar expeditions (land and maritime), and participation of Russian scientists in international Arctic scientific organizations, etc. The university ASD is exemplified by the Russian leading universities – St. Petersburg State University, Moscow State University, Northern (Arctic) Federal University, etc. The study demonstrated that maintaining a dialogue on an ongoing basis within the framework of research and educational activities of universities can contribute to the systematic establishment of cooperation in other areas of international relations, the search for innovative solutions for the benefit of the development of the entire Arctic region.

The role of the Arctic Monitoring and Assessment Programme (AMAP) in reducing pollution of the Arctic and around the globe

This article presents the initiation and implementation of a systematic scientific and political cooperation in the Arctic related to environmental pollution and climate change, with a special focus on the role of the Arctic Monitoring and Assessment Programme (AMAP). The AMAP initiative has coordinated monitoring and assessments of environmental pollution across countries and parameters for the entire Arctic region. Starting from a first scientific assessment in 1998, AMAP's work has been fundamental in recognizing, understanding and addressing environmental and human health issues in the Arctic, including those of persistent organic pollutants (POPs), mercury, radioactivity, oil, acidification and climate change. These scientific results have contributed at local and international levels to define and take measures towards reducing the pollution not only in the Arctic, but of the whole globe, especially the contaminant exposure of indigenous and local communities with a traditional lifestyle. The results related to climate change have documented the rapid changes in the Arctic and the strong feedback between the Arctic and the rest of the world. The lessons learned from the work in the Arctic can be beneficial for other regions where contaminants may accumulate and affect local and indigenous peoples living in a traditional way, e.g. in the Himalayas. Global cooperation is indispensable in reducing the long-range transported pollution in the Arctic.

A modified thermodynamic sea ice model and its application

A modified thermodynamic sea ice model suitable for large-scale climate simulations is described. Originated from the Winton’s three-layer model framework, this new model includes several improvements in the vertical thermodynamics: (1) the number of ice layers increases from two to three; (2) the snow heat capacity is included; (3) a vertically varying salinity profile is implemented; and (4) a temperature- and salinity-dependent heat conductivity parameterization scheme is introduced. A non-iterative fully implicit time-stepping scheme similar to Winton’s model is used to calculate the temperature of ice and snow. Results from a series of one-dimensional experiments show that equilibrium ice thickness in the modified model is increased by 45 cm when compared with the original Winton’s model. All modifications mentioned above contribute to this change of ice thickness, among which the increase of ice layer has the most significant effect. Experiments using the Modular Ocean Model version 4 (MOM4) coupled with the modified model show an improved sea ice simulation which includes an increase in both the sea ice volume and thickness over the entire Arctic region, confirming the above founding. However, contrary model behavior exhibits when the snow heat capacity is considered that warrants further investigation.

Stratigraphy, Lithology, and Geochemistry of Coastal and Shallow-Sea Sections of the Uppermost Middle Jurassic–the Lowermost Cretaceous Section in the Anabar River Region (Arctic Siberia)

Abstract —Concepts of the stratigraphy of the coastal and shallow-sea sections of the uppermost Middle Jurassic and Lower Cretaceous, exposed on the right bank of the Anabar River, have radically changed many times. The performed study and analysis of the published data are aimed at refining the bio- and lithostratigraphic subdivision of the section, substantiating its stratigraphic completeness, and describing the identified stratigraphic units in detail. Comprehensive biostratigraphic studies of the uppermost Bathonian — the lowermost Boreal Berriasian reveal a sequence of nine biostratigraphic units with dinocysts and palynoflora in the ranks of zones and local zones. Some of the palynological biostratigraphic units have been identified for the first time. Foraminiferal assemblages of the boreal standard zones are recorded in the sections under study. The obtained biostratigraphic data and analysis of all known ammonite occurrences make it possible to demonstrate the stratigraphic continuity of the section in the Anabar River region, despite the reduced thickness of the stratigraphic units. The stratigraphic position of the boundary between the Sodiemykha and Buolkalakh formations is accurately defined. According to the interpretation proposed, the basal horizon of the Buolkalakh Formation is associated with a beginning of a new major sedimentation stage in the late Oxfordian–early Kimmeridgian, identified as the lower boundary of lithostratigraphic units of different ranks throughout the entire Arctic Region and partially in the Boreal Region. The lithogeochemical parameters of the studied formations are obtained for the first time. The content of Corg in the studied samples does not exceed its Clarke values, and the pyrolytic parameter Tmax indicates that the organic matter is immature and the petroleum potential is low. The considered organic matter of the rocks is characterized by a heavy isotope composition of carbon, suggesting its mostly terrigenous genesis.

Investigating Thaw and Plant Productivity Constraints on Old Soil Carbon Respiration From Permafrost

AbstractIsotopic radiocarbon (Δ14C) signatures of ecosystem respiration (Reco) can identify old soil carbon (C) loss and serve as an early indicator of permafrost destabilization in a warming climate. Warming also stimulates plant productivity causing plant respiration to dominate Reco Δ14C signatures and potentially obscuring old soil C loss. Here, we investigate how a wide spatio‐temporal gradient of permafrost thaw and plant productivity affects Reco Δ14C patterns and isotopic partitioning. Spatial gradients came from a warming experiment with doubling thaw depth and variable biomass, and a vegetation removal manipulation to eliminate plant contributions. We sampled in August and September to capture transitions from high to low plant productivity, decreased surface soil temperature, and relatively small seasonal thaw extensions. We found that surface processes dominate spatial variation in old soil C loss and a process‐based partitioning approach was crucial for constraining old soil C loss. Resampling the same plots in different times of the year revealed that old soil C losses tripled with cooling surface temperature, and the largest old soil C losses were detected when the organic‐to‐mineral soil horizons thawed (∼50–60 cm). We suggest that the measured increase in old soil respiration over the season and when the organic‐to‐mineral horizon thawed, may be explained by mobilization of nitrogen that stimulates microbial decomposition at depth. Our results suggest that soil C in the organic to mineral horizon may be an important source of soil C loss as the entire Arctic region warms and could lead to nonlinearities in projected permafrost climate feedbacks.

Decadal phase shift of summertime Arctic dipole pattern and its nonlinear effect on sea ice extent

AbstractThe rapid decline in Arctic sea ice during recent decades has been attributed to the combined influence of global warming and internal climate variability. Herein, we elucidate the process by which the decrease in sea ice is accelerated in association with the decadal phase shift of the Arctic dipole (AD), using observational data and Community Earth System Model (CESM1) simulations. The influence of the AD on Arctic sea ice varied according to its phase; in the negative‐AD decades (1979–1998), atmospheric circulation during summers of positive phase AD acts to reduce the sea ice extent (SIE) in the Pacific sector but increases it in the Atlantic sector. In contrast, in the positive‐AD decades (after 1999), the same atmospheric circulation pattern reduces the SIE in both sectors, resulting in enhanced sea ice melting across the entire Arctic region. A similar nonlinear relationship between the AD phase and SIE change is also observed in CESM1 Pre‐Industrial simulations, which stem from altered background temperature conditions between periods, implying the significant role of internal variability, particularly over the Atlantic sector. However, contrary to the recently observed AD trend, CESM1 Large Ensemble experiments predicted a negative AD trend as global warming proceeded. This suggests that the recent positive AD phase may be naturally driven, but the current state of sea ice decline associated with AD could be altered in the near future because of enhanced global warming.

RETRACTED ARTICLE: Structural features of ecotourism in the field of its implementation in the Arctic region

The Arctic region stands out due to its capability to host a large number of tourists without compromising the ecological situation of the territory. In particular, the potential capacity of the tourism market is several times higher than the one existing in accordance to the established development standards. The basis of tourism in the Arctic regions is ecological tourism, which has the least impact on the environment. We see the relevance of the study in identifying limits that should be expanded to achieve the required parameters for the development of ecological tourism. An expert study was performed involving 101 experts; experts needed to rank 33 types of tourism. Next, the variable series were calculated, after which 6 groups of types of tourism were obtained. The considered specific features, which make up the potential of ecotourism, provide an opportunity for further identification of indicators that can be used to assess the potential of ecotourism. The novelty of the study is that for the first-time ecological tourism is considered not as a general procedure in the tourism complex of the region, but as the main category of economic product. The paper points out the understanding of ecological tourism in the Arctic zone of the Russian Federation and considers aspects of managing its development. The practical application of the study may be the sphere of development of depressed territories, which essentially covers the entire Arctic region. The authors believe that the application of the developed management tools will diversify the economy of the region at large.

Sustainable resource development in the Arctic: Using export trade agreements to restrict environmentally harmful subsidies

Abstract Although the Arctic is emerging as a promising region for energy development and maritime transportation, navigational safety is a persistent and growing concern. What can international trade regulations do to ensure the safe transportation of natural resources on the Northern Sea Route (NSR) and the sustainable development of the Arctic region? Government support is almost inevitable for shipyards, particularly in a highly competitive market. Shipyards build large-scale vessels that navigate the Arctic Ocean. However, excessive export competition will soon lead to over-production and exportation of substandard products. Assuming that even a single incident in the NSR could have a disastrous impact on the flora and fauna of the entire Arctic region, the potential for substandard vessel use represents a significant risk and potential damage to the environment. Although the World Trade Organization (WTO) has detailed rules for this purpose with an effective dispute settlement mechanism, the history of WTO disputes has proven that WTO proceedings sometimes result in unintended consequences. As an alternative option, along with negotiations under the WTO and the Organisation for Economic Cooperation and Development (OECD), this paper suggests the possibility of a critical mass agreement to mutually allow more flexible government support for vessels only if they have superior environmental performance.

Summer albedo variations in the Arctic Sea ice region from 1982 to 2015

AbstractThe spatiotemporal changes in the sea ice region albedo over the entire Arctic region and in eight subregions (the Central Arctic Ocean [CAO], the Beaufort and Chukchi Seas [BC], the East Siberian and Laptev Seas [ESL], Baffin Bay and Labrador Sea [BL], the Canadian Archipelago [CA], the Greenland Sea [GS], Hudson Bay [HB] and the Kara and Barents Seas [KB]) in the summer of 1982–2015 are analysed with CLARA‐A2‐SAL data. The results indicate that in the summer of 1982–2015, the Arctic Sea ice region albedo fluctuated with a downward trend of −1.6% per decade (significance level of 99%). The BC had the largest decline in the albedo trend of −2.7% per decade (significance level of 99%), and most other subregions had downward trends except the GS, which exhibited a slight upward trend. The mean Arctic Sea ice region albedo was 44%. The high albedo areas were mainly concentrated in the CAO and the vicinity of Greenland. The albedo decreased with decreasing latitude, while the low‐value areas were mainly concentrated in the outer sea ice area. In the Arctic region, both the sea ice concentration (SIC) and the sea ice extent (SIE) showed a decreasing trend, while the near‐surface air temperature (NSAT) and the summer Central Arctic Index (CAI) showed an increasing trend. The Arctic Sea ice region albedo was positively correlated with the SIC and the SIE (0.84, 0.78) and negatively correlated with the NSAT (−0.72), all with a statistical significance level of 99%. The correlation between sea ice region albedo and the summer CAI revealed different relationships in these regions. The BC and ESL had a significant negative correlation, and the GS showed a significant positive correlation. These findings indicated that the decrease in albedo is closely related to the reduction in Arctic Sea ice and the increase in air temperature. In addition, the sea ice region albedo variations in the BC, ESL and GS are also greatly influenced by atmospheric circulation.

Optimal Arctic Port locations: a quantitative composite multiplier analysis of potential sites

ABSTRACTThe opening of the Arctic presents opportunities for expanded natural resource extraction and increased shipping, both requiring substantial port development to facilitate safe and effective operations. The remoteness and sparsity of Arctic ports requires each port to serve multiple functions – facilitating local and international trade, safety and security, and navigation and emergency services – while respecting the environmentally sensitive surroundings. Evaluating principal location criteria over the entire Arctic region identifies the optimal port locations that would increase the availability of port services while minimizing the number, and therefore impact of Arctic ports. This paper provides a quantitative composite multiplier method to create a unique Port Impact Value (PIV) for 185 potential port locations using the five most cited port development criteria: Proximity to Natural Resources, Proximity from Environmentally Sensitive Areas, Distance to Nearest Shipping Lane, Harbor Depth, and Multimodal Transport Connectivity. The PIV provides the first comprehensive quantitative ranking of Arctic ports and identifies eight optimal port locations that most effectively provide the required expansion of the Arctic port services with minimal environmental disruption.

Map Provides High-Resolution Look at Nearly Entire Arctic Region

Researchers highlight the value of the time element incorporated into imagery and having a baseline for revisiting and comparing topography.

Locals and immigrants on the Yamal Peninsula. Social boundaries and variations in migratory experience

ABSTRACTWestern Siberia and the entire Arctic region have been a beacon for migrants from the European part of Russia, from the national republics and the southern regions of Siberia in the post-war era. In contrast with the other regions of Siberia, the oil- and gas-rich North remains a magnet for migration from the entire former Soviet Union to this day. This paper presents research into the contemporary sociocultural environment of Yar-Sale, the administrative centre of the Yamal district of Yamalo-Nenets Autonomous Okrug. The research focuses on the migrational experiences of ‘new’ migrants and their relations with the native Nenets population. Special attention is paid to concepts such as ‘local’/‘immigrant’, and ‘insider’/‘outsider’. The author holds that the boundaries between these categories are flexible. An immigrant may become a local and an insider may become an outsider, with ethnicity far from always being the deciding factor.

Pan-Arctic aerosol number size distributions: seasonality and transport patterns

Abstract. The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500 nm from five sites around the Arctic Ocean (Alert, Villum Research Station – Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed.A cluster analysis of the aerosol number size distributions revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intra- and an inter-monthly scale. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, increases gradually to ∼ 40 % from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic haze aerosols is minimal in summer and peaks in April at all sites.The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and western Russia is associated with relatively high concentrations of accumulation-mode particles (Nacc) at all five sites – often above 150 cm−3. There are also indications of air descending into the Arctic boundary layer after transport from lower latitudes.The analysis of the back-trajectories together with the meteorological fields along them indicates that the main driver of the Arctic annual cycle of Nacc, on the larger scale, is when atmospheric transport covers the source regions for these particles in the 10-day period preceding the observations in the Arctic. The scavenging of these particles by precipitation is shown to be important on a regional scale and it is most active in summer. Cloud processing is an additional factor that enhances the Nacc annual cycle.There are some consistent differences between the sites that are beyond the year-to-year variability. They are the result of differences in the proximity to the aerosol source regions and to the Arctic Ocean sea-ice edge, as well as in the exposure to free-tropospheric air and in precipitation patterns – to mention a few. Hence, for most purposes, aerosol observations from a single Arctic site cannot represent the entire Arctic region. Therefore, the results presented here are a powerful observational benchmark for evaluation of detailed climate and air chemistry modelling studies of aerosols throughout the vast Arctic region.

Variability of mixed-phase clouds in the Arctic with a focus on the Svalbard region: a study based on spaceborne active remote sensing

Abstract. The Arctic region is known to be very sensitive to climate change. Clouds and in particular mixed-phase clouds (MPCs) remain one of the greatest sources of uncertainties in the modelling of the Arctic response to climate change due to an inaccurate representation of their variability and their quantification. In this study, we present a characterisation of the vertical, spatial and seasonal variability of Arctic clouds and MPCs over the entire Arctic region based on satellite active remote sensing observations. MPC properties in the region of the Svalbard archipelago (78° N, 15° E) are also investigated. The occurrence frequency of clouds and MPCs are determined from CALIPSO/CLOUDSAT measurements processed with the DARDAR retrieval algorithm, which allow for a reliable cloud thermodynamic phase classification (warm liquid, supercooled liquid, ice, mixing of ice and supercooled liquid). Significant differences are observed between MPC properties over the entire Arctic region and over the Svalbard region. Results show that MPCs are encountered all year long, with a minimum occurrence of 30% in winter and 50% during the rest of the year on average over the entire Arctic. Over the Svalbard region, MPC occurrence is more constant with time with larger values (55%) compared to the average observed in the Arctic. MPCs are especially located at low altitudes, below 3000 m, where their frequency of occurrence reaches 90%, particularly during winter, spring and autumn. Moreover, results highlight that MPCs are statistically more frequent above open sea than land or sea ice. The temporal and spatial distribution of MPCs over the Svalbard region seems to be linked to the supply of moister air and warmer water from the North Atlantic Ocean, which contribute to the initiation of the liquid water phase. Over the whole Arctic, and particularly in western regions, the increase of MPC occurrence from spring to autumn could be connected to the sea ice melting. During this period, the open water transports some of the warm water from the North Atlantic Ocean to the rest of the Arctic region. This facilitates the vertical transfer of moisture and thus the persistence of the liquid phase. Particular attention is also paid to the measurement uncertainties and how they could affect our conclusions.

Stratospheric aerosols from the Sarychev volcano eruption in the 2009 Arctic summer

Abstract. Aerosols from the Sarychev volcano eruption (Kuril Islands, northeast of Japan) were observed in the Arctic lower stratosphere a few days after the strongest SO2 injection which occurred on 15 and 16 June 2009. From the observations provided by the Infrared Atmospheric Sounding Interferometer (IASI) an estimated 0.9 Tg of sulphur dioxide was injected into the upper troposphere and lower stratosphere (UTLS). The resultant stratospheric sulphate aerosols were detected from satellites by the Optical Spectrograph and Infrared Imaging System (OSIRIS) limb sounder and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and from the surface by the Network for the Detection of Atmospheric Composition Changes (NDACC) lidar deployed at OHP (Observatoire de Haute-Provence, France). By the first week of July the aerosol plume had spread out over the entire Arctic region. The Sarychev-induced stratospheric aerosol over the Kiruna region (north of Sweden) was measured by the Stratospheric and Tropospheric Aerosol Counter (STAC) during eight balloon flights planned in August and September 2009. During this balloon campaign the Micro Radiomètre Ballon (MicroRADIBAL) and the Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON) remote-sensing instruments also observed these aerosols. Aerosol concentrations returned to near-background levels by spring 2010. The effective radius, the surface area density (SAD), the aerosol extinction, and the total sulphur mass from STAC in situ measurements are enhanced with mean values in the range 0.15–0.21 μm, 5.5–14.7 μm2 cm−3, 5.5–29.5 × 10−4 km−1, and 4.9–12.6 × 10−10 kg[S] kg−1[air], respectively, between 14 km and 18 km. The observed and modelled e-folding time of sulphate aerosols from the Sarychev eruption is around 70–80 days, a value much shorter than the 12–14 months calculated for aerosols from the 1991 eruption of Mt Pinatubo. The OSIRIS stratospheric aerosol optical depth (AOD) at 750 nm is enhanced by a factor of 6, with a value of 0.02 in late July compared to 0.0035 before the eruption. The HadGEM2 and MIMOSA model outputs indicate that aerosol layers in polar region up to 14–15 km are largely modulated by stratosphere–troposphere exchange processes. The spatial extent of the Sarychev plume is well represented in the HadGEM2 model with lower altitudes of the plume being controlled by upper tropospheric troughs which displace the plume downward and upper altitudes around 18–20 km, in agreement with lidar observations. Good consistency is found between the HadGEM2 sulphur mass density and the value inferred from the STAC observations, with a maximum located about 1 km above the tropopause ranging from 1 to 2 × 10−9 kg[S] kg−1[air], which is one order of magnitude higher than the background level.

Geological assessment of the East Greenland margin

The East Greenland margin consists of a number of sedimentary basins, platforms and structural highs (Figs 1, 2). Due to the challenges imposed by the Arctic climate, the region is in an early stage of exploration, and knowledge of the geology and petroleum potential of the margin is limited. However, the significant prospectivity of the conjugated European North Atlantic margin and the nature of the North-East Greenland onshore geology prompt for future offshore exploration. The US Geological Survey thus highlighted the North-East Greenland margin in their latest assessment of the Arctic region (Gautier et al. 2011). With a mean estimate of undiscovered recoverable oil, gas, and natural gas liquids of approximately 31 billion barrels of oil equivalents, the US Geological Survey ranked the North-East Greenland margin fourth in the entire Arctic region, only superseded by known producing petroleum provinces.
 In preparation for the initial East Greenland licence rounds in 2012 and 2013 the Geological Survey of Denmark and Greenland gathers geological information on the margin necessary for the decision process of the Greenland authorities regarding exploration. Geophysical analyses complemented by well-data, onshore geology and information from the conjugated Atlantic margin form the backbone of the study. The East Greenland margin is covered by an open seismic grid supplemented by gravimetric and magnetic data. All existing 2D seismic, gravimetric and magnetic data are included in the current study. Most of the data are confi-dential. Restricted by the general confidential nature of the project, this paper aims to summarise the geology of the East Greenland margin based on the current and previous studies and to briefly assess some of the implications for the regional petroleum prospectivity.

Properties of Sarychev sulphate aerosols over the Arctic

Aerosols from the Sarychev Peak volcano entered the Arctic region less than a week after the strongest SO2eruption on June 15 and 16, 2009 and had, by the first week in July, spread out over the entire Arctic region. These predominantly stratospheric aerosols were determined to be sub‐micron in size and inferred to be composed of sulphates produced from the condensation of SO2gases emitted during the eruption. Average (500 nm) Sarychev‐induced stratospheric optical depths (SOD) over the Polar Environmental Atmospheric Research Laboratory (PEARL) at Eureka (Nunavut, Canada) were found to be between 0.03 and 0.05 during the months of July and August, 2009. This estimate, derived from sunphotometry and integrated lidar backscatter profiles was consistent with averages derived from lidar estimates over Ny‐Ålesund (Spitsbergen). The Sarychev SOD e‐folding time at Eureka, deduced from lidar profiles, was found to be approximately 4 months relative to a regression start date of July 27. These profiles initially revealed the presence of multiple Sarychev plumes between the tropopause and about 17 km altitude. After about two months, the complex vertical plume structures had collapsed into fewer, more homogeneous plumes located near the tropopause. It was found that the noisy character of daytime backscatter returns induced an artifactual minimum in the temporal, pan‐Arctic, CALIOP SOD response to Sarychev sulphates. A depolarization ratio discrimination criterion was used to separate the CALIOP stratospheric layer class into a low depolarization subclass which was more representative of Sarychev sulphates. Post‐SAT (post Sarychev Arrival Time) retrievals of the fine mode effective radius (reff,f) and the logarithmic standard deviation for two Eureka sites and Thule (Greenland) were all close to 0.25 μm and 1.6 respectively. The stratospheric analogue to the columnar reff,f average was estimated to be reff,f(+) = 0.29 μm for Eureka data. Stratospheric, Raman lidar retrievals at Ny‐Ålesund, yielded a post‐SAT average of reff,f(+) = 0.27 μm. These results are ∼50% larger than the background stratospheric‐aerosol value. They are also about a factor of two larger than modeling values used in recent publications or about a factor of five larger in terms of (per particle) backscatter cross section.