Andrey Pnyushkov

University of Alaska Fairbanks · International Arctic Research Center

Two year-long (2004-05 and 2005-06) records of currents from two moorings deployed at the continental slope of the Laptev Sea (78°26'N, 125°40'E; ~2690 m) have been used in order to define the properties of tidal currents in the upper 200-m ocean layer. Harmonic and spectral analyses of currents showed that the solar semi-diurnal tidal constituent...

The Arctic Circumpolar Boundary Current (ACBC) transports a vast amount of mass and heat around cyclonic gyres of the deep basins, acting as a narrow, topographically-controlled flow, confined to the continental margins. Current observations during 2002–2011 at seven moorings along the major Atlantic Water (AW) pathway, complemented by an extensive...

Heat fluxes steered by mesoscale eddies may be a significant, but still not quantified, source of heat to the surface mixed layer and sea ice cover in the Arctic Ocean, as well as a source of nutrients for enhancing seasonal productivity in the near-surface layers. Here we use 4 years (2007–2011) of velocity and hydrography records from a moored pr...

This study discusses along-slope volume, heat, and salt transports derived from observations collected in 2013–2015 using a cross-slope array of six moorings ranging from 250 to 3900 m in the eastern Eurasian Basin (EB) of the Arctic Ocean. These observations demonstrate that in the upper 780 m layer, the along-slope boundary current advected, on a...

Mooring observations in the eastern Eurasian Basin of the Arctic Ocean showed that mean 2013–2018 along-slope volume and heat (calculated relative to the freezing temperature) transports in the upper 800 m were 4.8 ± 0.1 Sv (1 Sv = 106 m3/s) and 34.8 ± 0.6 TW, respectively. Volume and heat transports within the Atlantic Water (AW) layer (∼150–800 m...

Pan-Arctic observations of summer sea ice thickness have been a challenging problem despite their global significance in weather/climate analysis and prediction. To solve this problem, this study developed a method for estimating the pan-Arctic ice draft (depth of sea ice below sea surface level) using spaceborne passive microwave-measured brightne...

Enhanced warm, salty subarctic inflows drive high-latitude atlantification, which weakens oceanic stratification, amplifies heat fluxes, and reduces sea ice. In this work, we show that the atmospheric Arctic Dipole (AD) associated with anticyclonic winds over North America and cyclonic winds over Eurasia modulates inflows from the North Atlantic ac...

The study focuses on conducting a quantitative comparison of sea ice thickness data obtained through satellite-based remote sensing and in-situ observations in the eastern Arctic Ocean from September 2013 to September 2015 as part of the Nansen and Amundsen Basins Observational System (NABOS) program. Upward-looking sonar observations from an ocean...

We investigated liquid freshwater content (FWC) in the upper 100 m layer of the Arctic Ocean using oceanographic observations covering the period from 1990 through 2018. Our analysis revealed two opposite tendencies in freshwater balance—the freshening in the Canada Basin at the mean rate of 2.04 ± 0.64 m/decade and the salinization of the eastern...

This study traces the pathways of dissolved methane at the Eurasian continental slope (ECS) and the Siberian shelf break based on data collected during the NABOS-II expedition in August-September, 2013. We focus on the sea ice-ocean interface during seasonal strong ice melt. Our analysis reveals a patchy pattern of methane supersaturation related t...

On September 2, 2002, the Nansen and Amundsen Basins Observational System (NABOS) program deployed its first mooring in the Eastern Eurasian Basin (EEB) of the Arctic Ocean. Since then, NABOS moorings, complemented by repeat multidisciplinary shipborne surveys and Lagrangian drifters, have provided a unique data set in an area of traditionally spar...

The paper deals with global changes in regime and climate of Arctic basin. Changes in the content and inflows of freshwater into the upper 100 m layer of the Arctic basin from decade to decade (1950s – 2010s) were determined. Data from national expedition surveys of the Arctic Basin in the 1950s to the 1970s combined with data from expe- ditions in...

The diverse range of mechanisms driving the Arctic amplification and global climate are not completely understood and, in particular, the role of the greenhouse gas methane (CH4) in the Arctic warming remains unclear. Strong sources of methane at the ocean seabed in the Barents Sea and other polar regions are well documented. Nevertheless, some of...

On-line oral presentation summarizing results of GBC paper

The results of ice and hydrological studies of the shallow Bay of Braganzavågen (Van Mayen Fjord Bay, West Spitsbergen Island) in March 2016 and 2018, supplemented with model calculations using a thermodynamic model, are presented. The model uses both known methods of localizing the phase transition region-the classical (frontal) for fast ice and i...

Tidal and wind-driven near-inertial currents play a vital role in the changing Arctic climate and the marine ecosystems. We compiled 429 available moored current observations taken over the last two decades throughout the Arctic to assemble a pan-Arctic atlas of tidal band currents. The atlas contains different tidal current products designed for t...

Plain Language Summary Previous studies demonstrated that in recent years density gradients above the warm and salty intermediate (~150–900 m) water of Atlantic origin in the eastern Arctic Ocean have weakened, allowing stronger upward transport of heat to the bottom of the sea ice. Using mooring observations, we show that this weakening of stratif...

Data from coastal tide gauges, oceanographic moorings, and a numerical model show that Arctic storm surges force continental shelf waves (CSWs) that dynamically link the circumpolar Arctic continental shelf system. These trains of barotropic disturbances result from coastal convergences driven by cross-shelf Ekman transport. Observed propagation sp...

A 15-year duration record of mooring observations from the eastern (>70°E) Eurasian Basin (EB) of the Arctic Ocean is used to show and quantify the recently increased oceanic heat flux from intermediate-depth (∼150-900 m) warm Atlantic Water (AW) to the surface mixed layer (SML) and sea ice. The upward release of AW heat is regulated by the stabili...

An important yet still not well documented aspect of recent changes in the Arctic Ocean is associated with the advection of anomalous sub-Arctic Atlantic- and Pacific-origin waters and biota into the polar basins, a process which we refer to as borealization. Using a 37-year archive of observations (1981–2017) we demonstrate dramatically contrastin...

Inter-decadal changes in the water layer of Atlantic origin and freshwater content (FWC) in the upper 100 m layer were traced jointly to assess the influence of inflows from the Atlantic on FWC changes based on oceanographic observations in the Arctic Basin for the 1960s – 2010s. For this assessment, we used oceanographic data collected at the Arct...

In this study, we propose a new Arctic climate change indicator based on the strength of the Arctic halocline, a porous barrier between the cold and fresh upper ocean and ice and the warm intermediate Atlantic Water of the Arctic Ocean. This indicator provides a measure of the vulnerability of sea ice to upward heat fluxes from the ocean interior,...

The diffusive layering (DL) form of double-diffusive convection cools the Atlantic Water (AW) as it circulates around the Arctic Ocean. Large DL steps, with heights of homogeneous layers often greater than 10 m, have been found above theAWcore in the Eurasian Basin (EB) of the eastern Arctic. Within these DL staircases, heat and salt fluxes are det...

The Eurasian Basin (EB) of the Arctic Ocean is subject to substantial seasonality. We here use data collected between 2013 and 2015 from six moorings across the continental slope in the eastern EB and identify three domains, each with its own unique seasonal cycle: 1) The upper ocean ( < 100 m), with seasonal temperature and salinity differences of...

This study discusses along-slope volume, heat, and salt transports derived from observations collected in 2013–15 using a cross-slope array of six moorings ranging from 250 m to 3900 m in the eastern Eurasian Basin (EB) of the Arctic Ocean. These observations demonstrate that in the upper 780 m layer, the along-slope boundary current advected, on a...

In this contribution, we present results from instrumental sea ice/ocean observations collected during the winter of 2014–15 in the Buor-Khaya Bay (southern Laptev Sea; Arctic Ocean). An observational analysis was complemented by numerical simulations, with a conceptual, one-dimensional thermodynamic model employed to describe the formation of sea...

Heat fluxes steered by mesoscale eddies may be a significant (but still not quantified) source of heat to the surface mixed layer and sea ice cover in the Arctic Ocean, as well as a source of nutrients for enhancing seasonal productivity in the near-surface layers. Here we use four years (2007–2011) of velocity and hydrography records from a moored...

The Eurasian Basin of the Arctic Ocean is subject to substantial seasonality in temperature and salinity. We here use data collected between 2013 and 2015 from six moorings across the continental slope in the eastern Eurasian Basin to identify three subdomains, each with its own unique seasonal cycle: 1) The upper ocean with seasonal fluctuations i...

The Eurasian Basin of the Arctic Ocean is subject to substantial seasonality in temperature and salinity. We here use data collected between 2013 and 2015 from six moorings across the continental slope in the eastern Eurasian Basin to identify three subdomains, each with its own unique seasonal cycle: 1) The upper ocean with seasonal fluctuations i...

A series of cross-slope transects were occupied in 2013 and 2015 that extended eastward from St. Anna Trough to the Lomonosov Ridge. High-resolution physical and chemical observations collected along these transects revealed fronts in the potential temperature and the stable oxygen isotopic ratio (δ18O) that were observed north of Severnaya Zemlya...

In the recent decade, the Arctic Ocean has experienced dramatic changes evident in all components of the climate system, e.g., in sea ice cover, thermohaline state, and freshwater budget; and there is no indication that they will discontinue in the near future (e.g., Cavalieri et al., 2012; Jeffries et al., 2013). The role of oceanic processes in t...

A series of cross-slope transects were occupied in 2013 and 2015 that extended eastward from St. Anna Trough to the Lomonosov Ridge. High-resolution physical and chemical observations collected along these transects revealed fronts in the potential temperature and the stable oxygen isotopic ratio (δ¹⁸O) that were observed north of Severnaya Zemlya...

Losing its character The eastern Eurasian Basin of the Arctic Ocean is on the far side of the North Pole from the Atlantic, but it is becoming more like its larger neighbor as the climate warms. Polyakov et al. show that this region is also evolving toward a state of weakened stratification with increased vertical mixing, release of oceanic heat, a...

The results of oceanographic and sea ice studies in the shallow Braganzavågen Gulf (Van Mijenfjorden, Svalbard) in March 2016 are presented. These studies are a continuation of observational efforts initiated by UNIS (Svalbard, Norway) in 2014. 2016 field campaign includes instrumental measurements of snow and ice properties in the fjord (e.g., ice...

presentation at ILTS seminar

This presentation provides an overview of recent oceanographic expeditions in the eastern part of the Arctic Ocean aimed at understanding how changes in sea ice regime in the Arctic affects physical conditions in the polar ocean.

We analyze mooring data collected along the continental slope of the Eurasian Basin in 2007-11 to improve the characterization of Arctic mesoscale eddies. Wavelet analyses suggest that ~20% of the mooring record is occupied by mesoscale eddies, whose vertical scales can be large, often >600 m. These eddies carry anomalous water properties along the...

This presentation provides the estimates of volume, heat and salt transports by the ACBC in the eastern Eurasian Basin (EB) of the Arctic Ocean using temperature, salinity and velocity observations collected by Nansen and Amundsen Basins Observational System (NABOS) program at six moorings distributed at the continental slope of the Laptev Sea in 2...

Regional Oceanic Modeling System (ROMS) Regional Oceanic Modeling System (ROMS) is a 3D, primitive equations, Boussinesq, hydrostatic, free-surface ocean model in an s-coordinate system (Shсhepetkin and McWilliams 2005) which is used by the scientific community for a wide range of applications (e.g., Haidvogel et al., 2000; Marchesiello et al., 200...

NABOS observations evaluate shift to more dynamic state of the eastern Arctic Ocean

Some preliminary results of NABOS 2015 expedition

A conceptual thermodynamic model of seasonal freezing of water column and underlying layer of bottom sediments, which is based on the solution of heat- and mass transfer equations in saline porous media, was elaborated. This model uses two distinct methods, simulating phase transitions in water and ground layers. Using realistic atmospheric forcing...

Preliminary results from 114 dual headed LADCP (Lowered Acoustic Doppler Current Profiler) measurements performed during the NABOS (Nansen and Amundsen Basin Observational System) 2013 cruise in the Eurasian Basin of the Arctic Ocean are discussed. Calculated horizontal magnetic field strength for that specific study area and cruise time span equal...

The pan-Arctic boundary current provides the largest input of water, heat, and salt into the Arctic Ocean. Recent observations captured strong changes in the Eurasian and Makarov basins (EMB); understanding the transition requires tracing the intensity of this major subsurface transport system. Responding to urgent needs for a long-term observation...

The presentation was aimed to illuminate wide range of possibilities available for carrier development of young scientists like myself as a NABOS team member. It was shown that NABOS provides excellent opportunity for young scientists to be involved in scientific research, expedition activities, operations with state-of-the-art instruments and new...

We examine general structure (vertical and spatial) and temporal variability of pan-arctic boundary current (BC) in the Eurasian Basin (EB) of the Arctic Ocean using observations at several moorings located at EB continental slope, complemented by results of state-of-the-art numerical modeling. Observations suggest gradual decrease of speed of the...

This synthesis study assesses recent changes of Arctic Ocean physical parameters using a unique collection of observations from the 2000s and places them in the context of long-term climate trends and variability. Our analysis demonstrates that the 2000s were an exceptional decade with extraordinary upper Arctic Ocean freshening and intermediate At...

A one year (2009–2010) record of temperature and salinity profiles from Ice Tethered Profiler (ITP) buoys in the Eurasian Basin (EB) of the Arctic Ocean is used to quantify the flux of heat from the upper pycnocline to the surface mixed layer. The upper pycnocline in the central EB is fed by the upward flux of heat from the intermediate depth (~150...

Recent mooring-based observations at several locations along the continental slope of the Arctic Ocean's Eurasian Basin showed a transformation of the Boundary Current (BC) from a mostly barotropic flow in Fram Strait to a jet-like baroclinic current northeast of Svalbard, and the reemergence of the barotropic structure of the flow in the eastern E...

This analysis evaluates the thermal state of the intermediate (depth range of 150–900 m) Atlantic Water (AW) of the Arctic Ocean, beginning in the 1950s and with particular focus on the transition from the 1990s to the 2000s and on changes during the 2000s. Using an extensive array of observations, the authors document AW warming trends across vari...

The peculiarities of flaw lead freezing were studied using the conceptual thermodynamic model. Mechanism of polynya forming under wind stress was analysed. Qquantitative characteristics of sea ice evolution for the Northeastern Taimyr area of Laptev Sea were obtained with the use of NCEP/NCAR reanalysis data as the atmospheric forcing.

Mooring-based high-resolution profiles of water temperature and salinity from the Laptev Sea slope (2003-04, 2686m depth, 78°26'N, 125°37'E) show six remarkably persistent staircase layers in the upper Atlantic Water (AW) and lower halocline (~140-350m depth range). Despite persistent displacement of isopycnal surfaces associated, probably, with in...

The features of the sea ice growing and melting under the modern climatic conditions are considered with the use of the thermodynamic model of sea ice taking into account the seasonal melting and recrystallization of its upper layers. The evolution of the snowy and icy cover for the North Pole geographic point is estimated quantitatively on the bas...

Conceptual thermodynamical model of seasonal freezing of sea water layer and underwater ground, which takes into account air-sea energy and mass exchange processes, is presented in this study. A special feature of the model is combination of phase transition approaches – frontal one is for fast-ice and in temperature range approach is for the under...

Two year-long (2004-05 and 2005-06) records of currents from two moorings deployed at the continental slope of the Laptev Sea (78°26'N, 125°40'E; ~2690 m) have been used in order to define the properties of tidal currents in the upper 200-m ocean layer. Harmonic and spectral analyses of currents showed that the solar semi-diurnal tidal constituent...

The data on water mass, sea ice and atmosphere collected during the IPY 2007–08 period and a combination of these new data with the data collected earlier made it possible to follow the development of the climatic phenomenon of the end 1990s – beginning 2000s in the sea Arctic, to deduce its relationship with the global climate change and to compar...

The pan-Arctic Boundary Current (BC) provides the largest input of water, heat, and salt into the Polar Basins. Recent mooring-based observations at several locations along the continental slope of the Arctic Ocean's Eurasian Basin showed a transformation of the BC from a mostly barotropic flow in Fram Strait to a jet-like baroclinic current northe...

The formation of fast ice in the costal zone of freezing seas (immobile ice) is considered on the basis of a specially developed thermodynamic model that takes into account the energy exchange in the atmospheric boundary layer and the salinification of the water layer under the ice. The conditions at which the wind forced onshore motion of the ice...

The process of seaice forming and evolution in circumpolar flaw leads was studied using conceptual thermodynamic model. The model is based on the non-stationary heat and mass transfer equations with moving interfaces applied for mushy (skeletal) zone that is transforming at the top into solid ice and takes into account the energy exchange processes...

The enhanced warming in the Arctic began in the middle of 1990s and maximized in 2007. During this period an abrupt shrinking of the summer ice extent occurred and significant positive anomaly of temperature in Atlantic Water (AW) layer in the Arctic Basin expanded over larger area. This climate shift coincided with the resumption of intensive fiel...

It is believed that circulation of the intermediate (150-800m) water of Atlantic origin (the so-called Atlantic Water, AW) in the eastern Arctic Ocean is topography-steered confining with deep-basin margins and enveloping the shelf breaks. However, recent observations from Fram Strait show barotropic structure of water transport. Mooring records fr...

A thermodynamic model of sea snow-ice cover growth under the influence of heat flows on its upper and lower surfaces is presented. The growing is described with an extended region of phase transition (a two-phase region) with a linear temperature distribution. The temperature of the upper surface is calculated with the use of a heat-balance equatio...

A system of oceanic reanalysis of the Nordic seas (Norwegian, Greenland and Barents seas) directed to the investigations of long period changes in the oceanic climate of the Arctic sub-polar seas was developed. The system of oceanic reanalysys (SOR) includes hybrid coordinate 22-th level ocean model HYCOM [Bleck,2002] and modern oceanographic data...

Oceanographic data sets including ones from IPY 2007/2008 were used to estimate the changes in the Arctic Ocean after 1990. New method is applied to construct large-scale oceanographic fields when observations are rare. It is allowed to present the oceanographic fields and their anomalies relatively 1970s climate on the large part of the Arctic Bas...

Constantly growing interests in high-resolution oceanographic fields stimulate compilation of comprehensive initial datasets and advanced methodology of the objective analysis. Observed level database for the Nordic Seas and the North Atlantic compiled from large amount of initial sources was recently considerably updated by adding historical and m...

The goal of the work was to study the thermodynamic evolution of sea ice in modern climate conditions. The model describes repetitive changing the processes of winter ice growth, snow summer melting and dissolution of ice upper layer and its autumn re-crystallization. Ice block uses classical (frontal) variant of Stefan problem and takes into consi...

The article considers technology of compiling oceanographic database for the North European Basin. A sequence of compiling «clean» datasets is discussed from merging the original datasets to computing the objectively analyzed fields of oceanographic parameters. Special attention is given to data quality control, objective analysis methodology and f...

The Nordic Seas (NS) that included Norwegian, Greenland and Barents seas play an important role in the global climate system. They have a strong effect on the climate of middle and high latitudes due to unique location on the border between Atlantic and Arctic oceans. Interannual and long period changes of air-ocean interaction intensity in the NS...