Decrease In Sea Ice Extent Research Articles

Iceberg production and characteristics around the Prince of Wales Icefield, Ellesmere Island, 1997-2015

ABSTRACTSince the 1960s, warming air and sea surface temperatures have led to decreasing sea ice extent and longer periods of open water in the Canadian Arctic Archipelago (CAA), together with changes in glacier discharge patterns. An important question, therefore, is whether there is a relationship between changing sea ice conditions, glacier dynamics, and iceberg production in this region. Using synthetic aperture radar (SAR) (Radarsat-1, Radarsat-2, and ALOS PALSAR) and optical (Landsat 7 and 8) satellite imagery, iceberg plume events and sea ice break-up/freeze-up dates between 1997 and 2015 are investigated for 40 tidewater glaciers around the Prince of Wales (POW) Icefield, Ellesmere Island. Results show a clear relationship between the presence of sea ice and the production of icebergs, with ~49% of total iceberg plume events occurring during the 3–4 month long summer open water season and ~51% of events when sea ice was present the remaining 8–9 months of the year. There is no clear evidence of recent increases in iceberg production on a regional basis, but on a local, individual glacier scale there has been a connection between periods of increased iceberg plume events and: (a) acceleration in the surface velocity of Trinity and Wykeham glaciers; (b) increase in terminus retreat rates for glaciers which have not accelerated in flow speed over the past ~5–10 years. Comparisons with ocean temperature, surface air temperature from NCEP-NCAR reanalysis, and tidal data showed no clear relationship with iceberg plume events.

Processes Controlling the Composition and Abundance of Arctic Aerosol

AbstractThe Arctic region is a harbinger of global change and is warming at a rate higher than the global average. While Arctic warming is driven by increases in anthropogenic greenhouse gases' in combination with local feedback mechanisms, short‐lived climate forcing agents, such as tropospheric aerosol, are also important drivers of Arctic climate. Arctic aerosol‐climate impacts vary seasonally as a result of the interplay between aerosol and different cloud types, available solar radiation, sea ice, surface albedo, Arctic and lower latitude removal processes, and atmospheric transport patterns. Photochemistry and efficient wet aerosol removal have low impact in winter but become important in spring to summer, dramatically altering aerosol chemical composition, and driving the size distribution from a pronounced accumulation mode toward a dominance of smaller particles. Retreating sea ice, increasing solar insolation and warmer temperatures in summer result in enhanced emissions from Arctic marine and terrestrial ecosystems, and anthropogenic sources, with impacts on the composition of gas and particle phases. Fractional cloud cover reaches a maximum in Arctic summer, in parallel with decreasing sea ice extent and surface albedo. This seasonal variation corresponds to significant changes in the net cloud radiative effect; changes that are affected by aerosol. This review summarizes our current knowledge of processes that control Arctic aerosol properties. We highlight both natural and anthropogenic processes that will be impacted by current and future sea ice loss. Efforts are needed to better constrain aerosol removal rates, characterize aerosol precursors, and constrain the seasonality and magnitude of aerosol‐cloud‐climate impacts.

A temporal shift in trophic diversity among a predator assemblage in a warming Arctic.

Climate change is leading to northward shifts in species distributions that is altering interspecific interactions at low- and mid-trophic levels. However, little attention has been focused on the effects of redistributions of species on the trophic ecology of a high trophic-level predator assemblage. Here, during a 22-year period (1990–2012) of increasing sea temperature (1.0°C) and decreasing sea ice extent (12%) in Cumberland Sound, Nunavut, Canada, we examined the trophic structure of a near-apex predator assemblage before (1990–2002) and after (2005–2012) an increase in the availability of capelin—generally an indicator species in colder marine environments for a warming climate. Stable isotopes (δ13C and δ15N) were used in a Bayesian framework to assess shifts in diet, niche size and community-wide metrics for beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), Greenland halibut (Reinhardtius hippoglossoides) and anadromous Arctic char (Salvelinus alpinus). After 2005, consumption of forage fish increased for all predator species, suggesting diet flexibility with changing abiotic and biotic conditions. An associated temporal shift from a trophically diverse to a trophically redundant predator assemblage occurred where predators now play similar trophic roles by consuming prey primarily from the pelagic energy pathway. Overall, these long-term ecological changes signify that trophic shifts of a high trophic-level predator assemblage associated with climate change have occurred in the Arctic food web.

Atmospheric influences on the anomalous 2016 Antarctic sea ice decay

Abstract. In contrast to the Arctic, where total sea ice extent (SIE) has been decreasing for the last three decades, Antarctic SIE has shown a small, but significant, increase during the same time period. However, in 2016, an unusually early onset of the melt season was observed; the maximum Antarctic SIE was already reached as early as August rather than the end of September, and was followed by a rapid decrease. The decay was particularly strong in November, when Antarctic SIE exhibited a negative anomaly (compared to the 1979–2015 average) of approximately 2 million km2. ECMWF Interim reanalysis data showed that the early onset of the melt and the rapid decrease in sea ice area (SIA) and SIE were associated with atmospheric flow patterns related to a positive zonal wave number three (ZW3) index, i.e., synoptic situations leading to strong meridional flow and anomalously strong southward heat advection in the regions of strongest sea ice decline. A persistently positive ZW3 index from May to August suggests that SIE decrease was preconditioned by SIA decrease. In particular, in the first third of November northerly flow conditions in the Weddell Sea and the Western Pacific triggered accelerated sea ice decay, which was continued in the following weeks due to positive feedback effects, leading to the unusually low November SIE. In 2016, the monthly mean Southern Annular Mode (SAM) index reached its second lowest November value since the beginning of the satellite observations. A better spatial and temporal coverage of reliable ice thickness data is needed to assess the change in ice mass rather than ice area.

A decade of marine mammal acoustical presence and habitat preference in the Bering Sea

As Arctic seas rapidly change with increased ocean temperatures and decreased sea ice extent, traditional marine mammal distributions may be altered, and non-traditional Arctic species may shift poleward. Extant and seasonal continental shelf odontocete species in the Arctic Ocean include sperm whales, killer whales, beluga whales, delphinids, harbour porpoises, and Dall’s porpoises. Until recently, recording constraints limited higher sampling rates, preventing detection of many of these high frequency-producing species in the Arctic seas. Using one of the first long-term data sets to record clicks, buzzes, and whistles, multiple species have been detected and classified to explore shifting distributions in the Arctic Corridor. The data were then paired with environmental variables for generalized linear and additive modeling. Pacific white-sided dolphins were detected for a few years during minimal ice coverage. Dall’s porpoises and Risso’s dolphins may have been acoustically detected in areas farther n...

Peatland Ecosystem Processes in the Maritime Antarctic During Warm Climates

We discovered a 50-cm-thick peat deposit near Cape Rasmussen (65.2°S), in the maritime Antarctic. To our knowledge, while aerobic ‘moss banks’ have often been examined, waterlogged ‘peatlands’ have never been described in this region before. The waterlogged system is approximately 100 m2, with a shallow water table. Surface vegetation is dominated by Warnstorfia fontinaliopsis, a wet-adapted moss commonly found in the Antarctic Peninsula. Peat inception was dated at 2750 cal. BP and was followed by relatively rapid peat accumulation (~0.1 cm/year) until 2150 cal. BP. Our multi-proxy analysis then shows a 2000-year-long stratigraphic hiatus as well as the recent resurgence of peat accumulation, sometime after 1950 AD. The existence of a thriving peatland at 2700–2150 cal. BP implies regionally warm summer conditions extending beyond the mid-Holocene; this finding is corroborated by many regional records showing moss bank initiation and decreased sea ice extent during this time period. Recent peatland recovery at the study site (<50 years ago) might have been triggered by ongoing rapid warming, as the area is experiencing climatic conditions approaching those found on milder, peatland-rich sub-Antarctic islands (50–60°S). Assuming that colonization opportunities and stabilization mechanisms would allow peat to persist in Antarctica, our results suggest that longer and warmer growing seasons in the maritime Antarctic region may promote a more peatland-rich landscape in the future.

Direct determination of the air‐sea CO2 gas transfer velocity in Arctic sea ice regions

AbstractThe Arctic Ocean is an important sink for atmospheric CO2. The impact of decreasing sea ice extent and expanding marginal ice zones on Arctic air‐sea CO2 exchange depends on the rate of gas transfer in the presence of sea ice. Sea ice acts to limit air‐sea gas exchange by reducing contact between air and water but is also hypothesized to enhance gas transfer rates across surrounding open‐water surfaces through physical processes such as increased surface‐ocean turbulence from ice‐water shear and ice‐edge form drag. Here we present the first direct determination of the CO2 air‐sea gas transfer velocity in a wide range of Arctic sea ice conditions. We show that the gas transfer velocity increases near linearly with decreasing sea ice concentration. We also show that previous modeling approaches overestimate gas transfer rates in sea ice regions.

Movements of a deep-water fish: establishing marine fisheries management boundaries in coastal Arctic waters.

Management boundaries that define populations or stocks of fish form the basis of fisheries planning. In the Arctic, decreasing sea ice extent is driving increasing fisheries development, highlighting the need for ecological data to inform management. In Cumberland Sound, southwest Baffin Island, an indigenous community fishery was established in 1987 targeting Greenland halibut (Reinhardtius hippoglossoides) through the ice. Following its development, the Cumberland Sound Management Boundary (CSMB) was designated and a total allowable catch (TAC) assigned to the fishery. The CSMB was based on a sink population of Greenland halibut resident in the northern section of the Sound. Recent fishing activities south of the CSMB, however, raised concerns over fish residency, the effectiveness of the CSMB and the sustainability of the community-based winter fishery. Through acoustic telemetry monitoring at depths between 400 and 1200m, and environmental and fisheries data, this study examined the movement patterns of Greenland halibut relative to the CSMB, the biotic and abiotic factors driving fish movement and the dynamics of the winter fishery. Greenland halibut undertook clear seasonal movements between the southern and northern regions of the Sound driven by temperature, dissolved oxygen, and sea ice cover with most fish crossing the CSMB on an annual basis. Over the lifespan of the fishery, landfast ice cover initially declined and then became variable, limiting accessibility to favored fisher locations. Concomitantly, catch per unit effort declined, reflecting the effect of changing ice conditions on the location and effort of the fishery. Ultimately, these telemetry data revealed that fishers now target less productive sites outside of their favored areas and, with continued decreases in ice, the winter fishery might cease to exist. In addition, these novel telemetry data revealed that the CSMB is ineffective and led to its relocation to the entrance of the Sound in 2014. The community fishery can now develop an open-water fishery in addition to the winter fishery to exploit the TAC, which will ensure the longevity of the fishery under projected climate-change scenarios. Telemetry shows great promise as a tool for understanding deep-water species and for directly informing fisheries management of these ecosystems that are inherently complex to study.

A preliminary acoustic survey of echolocating marine mammals in the Bering Sea

As the Arctic seas rapidly change with increased ocean temperatures and decreased sea ice extent, traditional Arctic marine mammal distributions will be altered, and non-traditionally Arctic species may shift poleward. Arctic species typically include sperm, bowhead, humpback, right, gray, fin, and blue whales; odontocetes, specifically killer and beluga whales; and several pinnipeds species. Their acoustic presence has been documented because they produce relatively low-frequency sounds that are detectable by many common, remotely-deployed recording platforms. Until recently, however, recording constraints of power and storage limited higher sampling rates and prevented the detection of many high-frequency-producing species in the Arctic seas. Such species likely include Baird’s, Cuvier’s, and Stejneger’s beaked whales, as well as Northern right whale and Pacific white-sided dolphins. Using one of the first long-term data sets to record relatively high frequencies in the Bering Sea, signal types similar ...

Arctic Sea Ice: Decadal Simulations and Future Scenarios Using BESM-OA

Important international reports and a significant number of scientific publications have reported on the abrupt decline of Arctic sea ice and its impact on the Global Climate System. In this paper, we evaluated the ability of the newly implemented Brazilian Earth System Model (BESM-OA) to represent Arctic sea ice and sensitivity to CO2 forcing, using decadal simulations (1980-2012) and future scenarios (2006-2100). We validated our results with satellite observations and compared them to Coupled Model Intercomparison Project, Phase 5 (CMIP5) for the same numerical experiment. BESM results for the seasonal cycle are consistent with CMIP5 models and observations. However, almost all models tend to overestimate sea ice extent in March compared to observations. The correct evaluation of minimum record of sea ice, in terms of time, spatial and area remains a limitation in Coupled Global Climate Models. Looking to spatial patterns, we found a systematic model error in September sea ice cover between the Beaufort Sea and East Siberia for most models. Future scenarios show a decrease in sea ice extent in response to an increase in radiative forcing for all models. From the year 2045 onwards, all models show a dramatic shrinking in sea ice and ice free conditions at the end of the melting season. The projected future sea ice loss is explained by the combined effects of the amplified warming in northern hemisphere high latitudes and feedbacks processes.

Scaling observations of surface waves in the Beaufort Sea

Abstract The rapidly changing Arctic sea ice cover affects surface wave growth across all scales. Here, in situ measurements of waves, observed from freely-drifting buoys during the 2014 open water season, are interpreted using open water distances determined from satellite ice products and wind forcing time series measured in situ with the buoys. A significant portion of the wave observations were found to be limited by open water distance (fetch) when the wind duration was sufficient for the conditions to be considered stationary. The scaling of wave energy and frequency with open water distance demonstrated the indirect effects of ice cover on regional wave evolution. Waves in partial ice cover could be similarly categorized as distance-limited by applying the same open water scaling to determine an ‘effective fetch’. The process of local wave generation in ice appeared to be a strong function of the ice concentration, wherein the ice cover severely reduces the effective fetch. The wave field in the Beaufort Sea is thus a function of the sea ice both locally, where wave growth primarily occurs in the open water between floes, and regionally, where the ice edge may provide a more classic fetch limitation. Observations of waves in recent years may be indicative of an emerging trend in the Arctic Ocean, where we will observe increasing wave energy with decreasing sea ice extent.

New areas of polar lows over the Arctic as a result of the decrease in sea ice extent

Three mesocyclones (MCs) over the Russian (Eastern) Arctic are investigated using multispectral satellite remote sensing data, surface analysis maps, and reanalysis data. Advanced retrieval algorithms are used for estimating the geophysical parameter from satellite passive microwave measurements. These methods allow reconstructing in full the geophysical parameter fields characterizing polar lows. Synoptic analysis along with cloud image, atmospheric water vapor content, cloud liquid water content, and sea surface wind speed field analysis show that, while the Arctic sea ice retreats, new areas of open water appear where MCs can arise. A detailed study of several polar low cases reveals the typical conditions of their formation and development. Further studies are in demand due to the danger of MC extreme events for navigation, transport, and fishery operations in these unexplored regions.

An improved methodology for deriving high‐resolution surface shortwave radiative fluxes from MODIS in the Arctic region

AbstractThe Arctic is experiencing an unprecedented increase in surface air temperature and decrease in sea ice extent. The causes of these changes are still being debated; radiative fluxes are believed to play an important role in this warming. The primary motivation for this study is to advance the quality and resolution of currently available information on surface shortwave (solar) irradiance (SWR) for the Arctic. Such information is needed to meet the challenge for accurate estimates of heat input into the open waters. An inference scheme that utilizes the Moderate Resolution Imaging Spectroradiometer (MODIS) observations is optimized for high latitudes and implemented at 5 km for 2007 at an hourly time scale. Evaluation of the 5 km based SWR estimates against hourly ground observations at Barrow site shows a mean bias of 7.9 W m−2 (3% of mean values), a standard deviation of 58.2 W m−2 (23% of mean value), and a high correlation of 0.95. Evaluation of the SWR estimates against daily ground measurements at these latitudes shows good agreement with surface observations at three sites, with a mean bias of 1.9 W m−2 (1.1% of mean values), a standard deviation of 31.5 W m−2 (17.8% of mean value), and a high correlation of 0.96. Information at this high resolution and good quality can lead to improved estimates of heat input into the complex Arctic domain. For the Beaufort Sea domain (70°N–80°N, 120°E–50°E), the differences can amount to 116 MJ m−2 (~7%) of the total solar input of this region.

Air quality monitoring in communities of the Canadian Arctic during the high shipping season with a focus on local and marine pollution

Abstract. The Canadian Arctic has experienced decreasing sea ice extent and increasing shipping activity in recent decades. While there are economic incentives to develop resources in the north, there are environmental concerns that increasing marine traffic will contribute to declining air quality in northern communities. In an effort to characterize the relative impact of shipping on air quality in the north, two monitoring stations have been installed in Cape Dorset and Resolute, Nunavut, and have been operational since 1 June 2013. The impact of shipping and other sources of emissions on NOx, O3, SO2, BC, and PM2.5 pollution have been characterized for the 2013 shipping season from 1 June to 1 November. In addition, a high-resolution Air Quality Health Index (AQHI) for both sites was computed. Shipping consistently increased O3 mixing ratio and PM2.5 concentration. The 90% confidence interval for mean difference in O3 mixing ratio between ship- and no ship-influenced air masses were up to 4.6–4.7 ppb and 2.5–2.7 ppb for Cape Dorset and Resolute, respectively. The same intervals for PM2.5 concentrations were up to 1.8–1.9 μg m−3 and 0.5–0.6 μg m−3. Ship-influenced air masses consistently exhibited an increase of 0.1 to 0.3 in the high-resolution AQHI compared to no ship-influenced air masses. Trajectory cluster analysis in combination with ship traffic tracking provided an estimated range for percent ship contribution to NOx, O3, SO2, and PM2.5 that were 12.9–17.5 %, 16.2–18.1 %, 16.9–18.3 %, and 19.5–31.7 % for Cape Dorset and 1.0–7.2 %, 2.9–4.8 %, 5.5–10.0 %, and 6.5–7.2 % for Resolute during the 2013 shipping season. Additional measurements in Resolute suggested that percent ship contribution to black carbon was 4.3–9.8 % and that black carbon constituted 1.3–9.7 % of total PM2.5 mass in ship plumes. Continued air quality monitoring in the above sites for future shipping seasons will improve the statistics in our analysis and characterize repeating seasonal patterns in air quality due to shipping, local pollution, and long-range transport.

Observed and simulated changes in Antarctic sea ice extent over the past 50 years

Continuous monitoring of the polar regions by satellites has shown that sea ice extent (SIE) in the Antarctic has increased slightly since 1979. By contrast, climate model simulations including all major anthropogenic and natural climate influences simulate an average decrease in SIE since 1979. Here we take a longer view and assess the consistency of observed and simulated changes in Antarctic SIE using recently recovered satellite-based estimates of Antarctic SIE for September 1964 and May–July 1966, hence extending the current observational record from 35 to 50 years. While there is evidence of inconsistency between observed trends in Antarctic SIE and those simulated since 1979, particularly in models with realistic interannual variability, the observed trends since the mid-1960s fall within the 5–95% range of simulated trends. Thus, our results broadly support the hypothesis that the recent increase in Antarctic SIE is due to internal variability, though the reasons for the inconsistency in simulated and observed changes since 1979 remain to be determined.

The Antarctic Sea Ice Response to the Ozone Hole in Climate Models

Abstract It has been suggested that the increase of Southern Hemisphere sea ice extent since the 1970s can be explained by ozone depletion in the Southern Hemisphere stratosphere. In a previous study, the authors have shown that in a coupled atmosphere–ocean–sea ice model the ozone hole does not lead to an increase but to a decrease in sea ice extent. Here, the robustness of this result is established through the analysis of models from phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5). Comparison of the mean sea ice trends in CMIP3 models with and without time-varying stratospheric ozone suggests that ozone depletion is associated with decreased sea ice extent, and ozone recovery acts to mitigate the future sea ice decrease associated with increasing greenhouse gases. All available historical simulations with CMIP5 models that were designed to isolate the effect of time-varying ozone concentrations show decreased sea ice extent in response to historical ozone trends. In most models, the historical sea ice extent trends are mainly driven by historical greenhouse gas forcing, with ozone forcing playing a secondary role.

The Greenland Ice Sheet's surface mass balance in a seasonally sea ice‐free Arctic

General circulation models predict a rapid decrease in sea ice extent with concurrent increases in near‐surface air temperature and precipitation in the Arctic over the 21st century. This has led to suggestions that some Arctic land ice masses may experience an increase in accumulation due to enhanced evaporation from a seasonally sea ice‐free Arctic Ocean. To investigate the impact of this phenomenon on Greenland Ice Sheet climate and surface mass balance (SMB), a regional climate model, HadRM3, was used to force an insolation‐temperature melt SMB model. A set of experiments designed to investigate the role of sea ice independently from sea surface temperature (SST) forcing are described. In the warmer and wetter SI + SST simulation, Greenland experiences a 23% increase in winter SMB but 65% reduced summer SMB, resulting in a net decrease in the annual value. This study shows that sea ice decline contributes to the increased winter balance, causing 25% of the increase in winter accumulation; this is largest in eastern Greenland as the result of increased evaporation in the Greenland Sea. These results indicate that the seasonal cycle of Greenland's SMB will increase dramatically as global temperatures increase, with the largest changes in temperature and precipitation occurring in winter. This demonstrates that the accurate prediction of changes in sea ice cover is important for predicting Greenland SMB and ice sheet evolution.

Simulation and prediction of climate changes in the 19th to 21st centuries with the Institute of Numerical Mathematics, Russian Academy of Sciences, model of the Earth’s climate system

This paper presents results from a simulation of climate changes in the 19th–21st centuries with the Institute of Numerical Mathematics Climate Model Version 4 (INMCM4) in the framework of the Coupled Model Intercomparison Project, phase 5 (CMIP5). Like the previous INMCM3 version, this model has a low sensitivity of 4.0 K to a quadrupling of CO2 concentration. Global warming in the model by the end of the 21st century is 1.9 K for the RCP4.5 scenario and 3.4 K for RCP8.5. The spatial distribution of temperature and precipitation changes driven by the enhanced greenhouse effect is similar to that derived from the INMCM3 model data. In the INMCM4 model, however, the heat flux to the ocean and sea-level rise caused by thermal expansion are roughly 1.5 times as large as those in the INMCM3 model under the same scenario. A decrease in sea-ice extent and a change in heat fluxes and meridional circulation in the ocean under global warming, as well as some aspects of natural climate variability in the model, are considered.

Comparison between summertime and wintertime Arctic Ocean primary marine aerosol properties

Abstract. Primary marine aerosols (PMAs) are an important source of cloud condensation nuclei, and one of the key elements of the remote marine radiative budget. Changes occurring in the rapidly warming Arctic, most importantly the decreasing sea ice extent, will alter PMA production and hence the Arctic climate through a set of feedback processes. In light of this, laboratory experiments with Arctic Ocean water during both Arctic winter and summer were conducted and focused on PMA emissions as a function of season and water properties. Total particle number concentrations and particle number size distributions were used to characterize the PMA population. A comprehensive data set from the Arctic summer and winter showed a decrease in PMA concentrations for the covered water temperature (Tw) range between −1°C and 15°C. A sharp decrease in PMA emissions for a Tw increase from −1°C to 4°C was followed by a lower rate of change in PMA emissions for Tw up to about 6°C. Near constant number concentrations for water temperatures between 6°C to 10°C and higher were recorded. Even though the total particle number concentration changes for overlapping Tw ranges were consistent between the summer and winter measurements, the distribution of particle number concentrations among the different sizes varied between the seasons. Median particle number concentrations for a dry diameter (Dp&lt; 0.125μm measured during winter conditions were similar (deviation of up to 3%), or lower (up to 70%) than the ones measured during summer conditions (for the same water temperature range). For Dp &gt; 0.125μm, the particle number concentrations during winter were mostly higher than in summer (up to 50%). The normalized particle number size distribution as a function of water temperature was examined for both winter and summer measurements. An increase in Tw from −1°C to 10°C during winter measurements showed a decrease in the peak of relative particle number concentration at about a Dp of 0.180μm, while an increase was observed for particles with Dp &gt; 1μm. Summer measurements exhibited a relative shift to smaller particle sizes for an increase of Tw in the range 7–11°C. The differences in the shape of the number size distributions between winter and summer may be caused by different production of organic material in water, different local processes modifying the water masses within the fjord (for example sea ice production in winter and increased glacial meltwater inflow during summer) and different origin of the dominant sea water mass. Further research is needed regarding the contribution of these factors to the PMA production.

A comparison of the atmospheric conditions at Eureka, Canada, and Barrow, Alaska (2006–2008)

It is now well understood that the Arctic is particularly sensitive to climate change. Arctic sea ice is already undergoing significant changes. Some of the recent decrease in sea ice extent is due to changes in the surface energy budget, including the effect of clouds. Accurate ground‐based measurements of atmospheric and cloud properties are valuable for estimating components of the surface energy budget. In this paper, measurements made between 2006 and 2008 at the Canadian Network for the Detection of Arctic Change (CANDAC) site at Eureka, Nunavut, Canada (80°N, 86°W) and the Atmospheric Radiation Measurement (ARM) program site at Barrow, Alaska (71°N, 156°W) are used to examine differences in the atmospheres over the two sites, including the temperature, humidity, winds, and the downwelling longwave radiation flux. A method is developed to convert infrared radiances to downwelling longwave fluxes since broadband measurements of flux were not available at Eureka during the study period; the method is validated by comparing the fluxes at Barrow to independent measurements made by a pyrgeometer. Comparisons of the derived fluxes show significant differences between the two sites. Eureka is consistently colder and drier than Barrow, and the infrared effect of clouds on the surface energy budget is less. To examine the meteorological conditions that cause such differences, the ERA‐Interim reanalysis model is used; it is chosen over other models because it provides the best reproduction of longwave radiation at the surface. We find that the location of Eureka predisposes it to cold and dry air masses from the central Arctic Ocean and the Greenland Ice Sheet. In contrast, the air masses at Barrow come from a variety of directions, some of which are relatively warm and moist.