Vladimir Alexeev

University of Alaska Fairbanks · International Arctic Research Center

Monitoring and quantifying high‐latitude atmospheric circulation variability and trends are important toward understanding the anatomy of extreme events and constraining their probabilities under continued Arctic change. The greater Alaska region stands out as one region of enhanced warming and environmental changes over the Arctic Amplification er...

On the Arctic Coastal Plain (ACP) in northern Alaska (USA), permafrost and abundant surface‐water storage define watershed hydrological processes. In the last decades, the ACP landscape experienced extreme climate events and increased lake water withdrawal (LWW) for infrastructure construction, primarily ice roads and industrial operations. However...

Plain Language Summary Many current‐generation climate models have land components that are too shallow. Under climate change conditions, the long‐term warming trend at the surface propagates deeper into the ground than the commonly used 3–10 m. Shallow models alter the terrestrial heat storage and distribution of temperatures in the subsurface, in...

Observations show increases in river discharge to the Arctic Ocean especially in winter over the last decades but the physical mechanisms driving these changes are not yet fully understood. We hypothesize that even in the absence of a precipitation increase, permafrost degradation alone can lead to increased annual river runoff. To test this hypoth...

We explore the response of wintertime Arctic sea ice growth to strong cyclones and to large-scale circulation patterns on the daily scale using earth system model output in the Coupled Model Intercomparison Project phase five (CMIP5). A combined metrics ranking method selects three CMIP5 models that are successful in reproducing the wintertime Arct...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Abstract is available at: https://epic.awi.de/id/eprint/50808/

In North America and Asia, extreme cold weather characterized the winter of 2017–18. At the same time, the Pacific, the Bering Sea, and the Atlantic Arctic regions experienced anomalously low sea ice extent in the early winter. The jet stream dividing cold Arctic air from warm air deviated from normal zonal patterns northward into the ice-free area...

Vast mosaics of lakes, wetlands, and rivers on the Arctic Coastal Plain give the impression of water surplus. Yet long winters lock freshwater resources in ice, limiting freshwater habitats and water supply for human uses. Increasingly the petroleum industry relies on lakes to build temporary ice roads for winter oil exploration. Permitting water w...

Strong winter warming has dominated recent patterns of climate change along the Arctic Coastal Plain (ACP) of northern Alaska. The full impact of arctic winters may be best manifest by freshwater ice growth and the extent to which abundant shallow ACP lakes freeze solid with bedfast ice by the end of winter. For example, winter conditions of 2016-1...

Thirty models in phase 5 of the Coupled Model Intercomparison Project (CMIP5) are evaluated for their performances in reproducing two summertime atmospheric circulation patterns in the Arctic: the Arctic Oscillation (AO) and Arctic dipole (AD). The reference AO and AD are extracted from the ERA-Interim dataset (1979-2016). Model evaluation is condu...

БПЛА, неоднородный ландшафт, метеорологические параметры

This is the data set created by polar WRF version 3.5.1 forced by multiple forcings including a reanalysis data set (ERA-interim) and an Earth System Model (CESM1) over the domain of the Alaskan North Slope, with 10 km grid spacing and 3-hourly output interval. The available variables in this data set are temperature, precipitation, wind speed/dire...

Gradually decaying Arctic sea ice changes the boundary conditions at the surface, separating ocean and atmosphere. In recent years, substantial reductions in sea ice during winter have been observed in the Atlantic sector of the Arctic Ocean, which forms the gateway for warm water inflow from the midlatitudes. In this study, we used routine output...

This model‐based study assesses the response of the lower atmosphere and near‐surface permafrost on the North Slope of Alaska to projections in sea ice decline. The Weather Research and Forecast model, with polar optimization (polar WRF), was configured for the North Slope of Alaska and the adjacent Arctic Ocean and run for two decade‐long control...

We carried out upper air measurements with radiosondes during the summer over the Arctic Ocean from an icebreaker moving poleward from an ice-free region, through the ice edge, and into a region of thick ice. Rapid warming of the Arctic is a significant environmental issue that occurs not only at the surface but also throughout the troposphere. In...

Climate change is most pronounced in the northern high latitude region. Yet, climate observations are unable to fully capture regional-scale dynamics due to the sparse weather station coverage, which limits our ability to make reliable climate-based assessments. A set of simulated data products was therefore developed for the North Slope of Alaska...

Arctic sea ice over the last few decades has experienced a significant decline in coverage both in summer and winter. The currently warming Atlantic Water layer has a pronounced impact on sea ice in the Nordic Seas (including the Barents Sea). More open water combined with the prevailing atmospheric pattern of airflow from the southeast, and persis...

We discuss the possibility of detecting deep convection in the Lofoten Basin of the Norwegian Sea based on the eddy structures revealed from the satellite data. Satellite altimetry, SAR imagery, and MODIS satellite spectral radiometer sea-surface temperature (SST) data are used in the analysis, along with the data of oceanographic Argo floats. It i...

Climatic changes are most pronounced in northern high latitude regions. Yet, there is a paucity of observational data, both spatially and temporally, such that regional-scale dynamics are not fully captured, limiting our ability to make reliable projections. In this study, a group of dynamical downscaling products were created for the period 1950 t...

Field measurements, satellite observations, and models document a thinning trend in seasonal Arctic lake ice growth, causing a shift from bedfast to floating ice conditions. September sea ice concentrations in the Arctic Ocean since 1991 correlate well (r = +0.69, p < 0.001) to this lake regime shift. To understand how and to what extent sea ice af...

Climatic changes are most pronounced in northern high latitude regions. Yet, there is a paucity of observational data, both spatially and temporally, such that regional-scale dynamics are not fully captured, limiting our ability to make reliable projections. In this study, a group of dynamical downscaling products were created for the period 1950 t...

Broad, long-living, ice-free areas in midwinter northeast of Svalbard between 2011 and 2014 are investigated. The formation of these persistent and reemerging anomalies is linked, hypothetically, with the increased seasonality of Arctic sea ice cover, enabling an enhanced influence of oceanic heat on sea ice and, in particular, heat transported by...

Instead of «ground truth» precipitation, rain gauges at meteorological stations estimate a function of several variables. In addition to precipitation, these variables include temperature, wind, humidity, gauge type, state of the gauge exposure, and observational practices. Their impact and changes hamper our efforts to estimate precipitation chang...

The goal of this study was to assess the importance of the 2007 sea ice retreat for hydrologic conditions on the Alaskan North Slope, and how this may have influenced the outbreak of tundra fires in this region. This study concentrates on two years, 2007 and 1996, with different arctic sea ice conditions and tundra fire activity. The year of 2007 i...

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...

Surface albedo feedback is widely believed to be the principle contributor to polar amplification. However, a number of studies have shown that coupled ocean-atmosphere models without ice albedo feedbacks still produce significant polar amplification in 2 × CO2 runs due to atmospheric heat transports and their interaction with surface conditions. I...

Under conditions of decreasing ice cover the influence of ocean heat on Arctic sea ice is expected to increase. There are several ways how the ocean heat may be transferred towards the ice contributing to the existent ice thinning and/or impeding new ice formation. They include (i) Direct impact of sensible heat, stored in the ocean on the ice cove...

Warming of recent decades coincides with the overall increase in runoff from Siberian rivers to the Arctic Ocean. Significant changes in moisture budgets and contributing components have been observed. Changes in precipitation are usually considered as the primary cause of any alteration to the hydrological regime and this is often the default assu...

Precipitation is an essential and highly variable component of the freshwater budget, and solid precipitation in particular, has a major impact on the local and global climate. The impacts of snow on the surface energy balance are tremendous, as snow has a higher albedo than any other naturally occurring surface condition. Documenting the instrumen...

Arctic region is experiencing strong warming and related changes in the state of sea ice, permafrost, tundra, marine en-vironment and terrestrial ecosystems. These changes are found in any climatological data set comprising the Arctic re-gion. This study compares the temperature trends in several surface, satellite and reanalysis data sets. We demo...

Long-term thinning of arctic sea ice over the last few decades has resulted in significant declines in the coverage of thick multi-year ice accompanied by a proportional increase in thinner first-year ice. This change is often attributed to changes in the arctic atmosphere, both in composition and large-scale circulation, and greater inflow of warm...

Harassment by mosquitoes is an important factor influencing caribou (Rangifer tarandus) activity and movement patterns during summer (Kelsall, 1968; White et al., 1975; Russell et al., 1993). Incidence of mosquito activity, and consequently harassment to caribou is spatially and temporally dynamic in response to temperature and wind (Thomson, 1971;...

Одной из глобальных проблем, стоящих сегодня перед человечеством, является меняющийся планетарный климат. Несмотря на то, что взгляды ученых на первопричины наблюдаемых изменений климата весьма различны, факт наличия самих изменений сомнений не вызывает. Представляют большой научный и практический интерес количественная оценка современного состояни...

We focus on the Arctic Ocean between Svalbard and Franz Joseph Land in order to elucidate the possible role of Atlantic water (AW) inflow in shaping ice conditions. Ice conditions substantially affect the temperature regime of the Spitsbergen archipelago, particularly in winter. We test the hypothesis that intensive vertical mixing at the upper AW...

Surface albedo feedback is widely believed to be the principle contributor to polar amplification. However, a number of studies have shown that coupled ocean-atmosphere models without ice albedo feedbacks still produce significant polar amplification in 2xCO2 runs due to atmospheric heat transports and their interaction with surface conditions. In...

The most up to date consensus from global climate models predicts warming in the Northern Hemisphere (NH) high latitudes to middle latitudes during boreal winter. However, recent trends in observed NH winter surface temperatures diverge from these projections. For the last two decades, large-scale cooling trends have existed instead across large st...

Current consensus on global climate change predicts warming trends driven by anthropogenic forcing, with maximum temperature changes projected in the Northern Hemisphere (NH) high latitudes during winter. Yet, global temperature trends show little warming over the most recent decade or so. For longer time periods appropriate to the assessment of tr...

It is widely believed that the surface albedo feedback is the most important mechanism responsible for the polar amplified shape of surface warming in response to doubling the CO2 concentration. It has been shown that a pronounced polar amplified response can be obtained in an aquaplanet model with constant albedo of the surface. Atmospheric polar...

The global climate models predict that temperatures will warm the greatest in winter due to a positive feedback of increased greenhouse gases (GHGs) and a diminished and darker cryosphere. However, headlines on the two most recent years have been less about the extreme warmth and more about the severity of winter weather and record snowfalls. What...

This study diagnoses the changes in Arctic clouds simulated by the Community Climate System Model version 3 (CCSM3) in a transient 2 × CO2 simulation. Four experiments—one fully coupled and three with prescribed SSTs and/or sea ice cover—are used to identify the mechanisms responsible for the projected cloud changes. The target simulation uses a T4...

Observations show the warm pulse of Atlantic Water (AW) that entered the Arctic Ocean in the early 1990s has reached the Canada Basin during the 2000s. Observations from 2008-09 suggest that the recent warm surge has passed its peak in the Eurasian Basin, Data show apparently synchronous warming of the AW and the overlying layer (OL) at 125°E, whic...

Alaska Climate Research Center data (temperature and precipitation) is analyzed for changes in snow precipitation statistics. Data used span over period of 1947-2009. Frequency and intensity of snowfalls and their occurrence at different temperatures are studied. Trends in winter season snowfall are analyzed for different temperature intervals. The...

Over the past several decades, the Arctic regions have undergone substantial change. A high-latitude warming rate over 1875-2008 was 1.36°C/century, almost two times stronger than the Northern Hemisphere trend, with the accelerated warming rate in the recent decade (1.35°C/decade). Oceanographic data demonstrated that over the 20th century the cent...

We brought a party of 15 scientists, graduate students, and educators to King George Island, the largest of the South Shetland Islands, just off the Antarctic Peninsula, for an international workshop on Antarctica and global climate change in January 2010. Participants included professors, young scientists and graduate students from the Obukhov Ins...

Analysis of modern and historical observations demonstrates that the temperature of the intermediate-depth (150-900 m) Atlantic water (AW) of the Arctic Ocean has increased in recent decades. The AW warming has been uneven in time; a local ~1°C maximum was observed in the mid-1990s, followed by an intervening minimum and an additional warming that...

This study uses an extensive dataset of monthly surface air temperature (SAT) records (including previously unutilized) from high-latitude (>60°N) meteorological land stations. Most records have been updated by very recent observations (up to December 2008). Using these data, a high-latitude warming rate of 1.36°C century -1 is documented for 1875-...

Intensive field campaigns during the IPY (2007-2009) allowed unprecedented coverage of Eurasian continental slope by CTD measurements. These data allowed detailed mapping of the warm Atlantic water on its way from Fram Strait to the East Siberian Sea. Fourteen cross-slope sections, carried out by Russian, US and German scientists in August-Septembe...

This immersion experience exposed students from multiple disciplines and several nations to basic and advanced Antarctic research techniques necessary for understanding the area of the world most affected by climate change. This course offered a general overview of several fields, techniques and technologies used to collect and analyze data, hands-...

Climate fluctuations in the North Atlantic Ocean have wide-spread implications for Europe, Africa, and the Americas. This study assesses the relative contribution of the long-term trend and variability of North Atlantic warming using EOF analysis of deep-ocean and near-surface observations. Our analysis demonstrates that the recent warming over the...

Atlantic Water (AW) reaching the Arctic Ocean is considered to be the major heat source for the ocean interior. Under the progressing decay of the Arctic ice cap, potential effect of AW on this process is of high importance, particularly along with the currently observed temperature increase in AW layer. Multiple reports about substantial warming i...

An aquaplanet atmospheric GCM coupled to a mixed layer ocean is analyzed in terms of its polar amplified response to a 2xCO2-like forcing and in terms of phase space trajectory of the relaxation of a free perturbation to equilibrium. In earlier studies concerned with linear stability and fluctuation-dissipation analysis of the same system we have s...

Twentieth century North Atlantic and Arctic temperatures show two major warming events, one early in the century and another in recent decades. The earlier warming displays a high-latitude amplification whereas the recent warming lacks an enhanced high-latitude signal. This has led to the conclusion that different mechanisms operate for the two pea...

Arctic climate is the result of a complex interplay between the atmosphere, the ocean, sea ice and a terrestrial component in which freezing and thawing are critical to variations over a range of timescales. In view of the delicate balances between these components and their poorly documented sensitivities, it is not surprising that global climate...

An aquaplanet atmospheric GCM coupled to a mixed layer ocean is analyzed in terms of its polar amplified response to a 2xCO2-like forcing and in terms of phase space trajectory of the relaxation of a free perturbation to equilibrium. In earlier studies concerned with linear stability and fluctuation-dissipation analysis of the same system we have s...

Recent observations show dramatic changes of the Arctic atmosphere-ice-ocean system. Here the authors demonstrate, through the analysis of a vast collection of previously unsynthesized observational data, that over the twentieth century the central Arctic Ocean became increasingly saltier with a rate of freshwater loss of 239 ± 270 km3 decade-1. In...

Spatiotemporal patterns of recent (1979–2008) air temperature trends are evaluated using three reanalysis datasets and radiosonde data. Our analysis demonstrates large discrepancies between the reanalysis datasets, possibly due to differences in the data assimilation procedures as well as sparseness and inhomogeneity of high-latitude observations....

In November, 2007 a workshop was hosted by the International Arctic Research Center at the University of Alaska Fairbanks that had goals closely aligned with the NEESPI program. The goals of this workshop were to 1) describe observed changes in the Eurasian hydroclimatological system over the instrumental period from stations, gridded data, reanaly...