Arctic tidal characteristics at Eureka (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006/07: seasonal and longitudinal variations, migrating and non-migrating tides

Abstract. Operation of a Meteor Radar at Eureka, Ellesmere Island (80° N, 86° W) began in February 2006. The first 12 months of wind data (82–97 km) are combined with winds from the Adventdalen, Svalbard Island (78° N, 16° E) Meteor Radar to provide the first contemporaneous longitudinally spaced observations of mean winds, tides and planetary waves at such high Arctic latitudes. Unique polar information on diurnal non-migrating tides (NMT) is provided, as well as complementary information to that existing for the Antarctic on the semidiurnal NMT. Zonal and meridional monthly mean winds differed significantly between Canada and Norway, indicating the influence of stationary planetary waves (SPW) in the Arctic mesopause region. Both diurnal (D) and semi-diurnal (SD) winds also demonstrated significantly different magnitudes at Eureka and Svalbard. Typically the D tide was larger at Eureka and the SD tide was larger at Svalbard. Tidal amplitudes in the Arctic were also generally larger than expected from extrapolation of high mid-latitude data. For example time-sequences from ~90 km showed D wind oscillations at Eureka of 30 m/s in February–March, and four day bursts of SD winds at Svalbard reached 40 m/s in June 2006. Fitting of wave numbers for the migrating and non-migrating tides (MT, NMT) successfully determines dominant tides for each month and height. For the diurnal tide, NMT with s=0, +2 (westward) dominate in non-summer months, while for the semi-diurnal tide NMT with s=+1, +3 occur most often during equinoctial or early summer months. These wave numbers are consistent with stationary planetary wave (SPW)-tidal interactions. Assessment of the global topographic forcing and atmospheric propagation of the SPW (S=1, 2) suggests these winter waves of the Northern Hemisphere are associated with the 78–80° N diurnal NMT, but that the SPW of the Southern Hemisphere winter have little influence on the summer Arctic tidal fields. In contrast the large SPW and NMT of the Arctic winter may be associated, consistent with Antarctic observations, with the observed occurrence of the semidiurnal NMT in the Antarctic summer.

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Characteristics of Arctic tides at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

Annales Geophysicae ◽

10.5194/angeo-29-1939-2011 ◽

2011 ◽

Vol 29 (10) ◽

pp. 1939-1954 ◽

Cited By ~ 3

Author(s):

A. H. Manson ◽

C. E. Meek ◽

X. Xu ◽

T. Aso ◽

J. R. Drummond ◽

...

Keyword(s):

Middle Atmosphere ◽

Radar Data ◽

High Arctic ◽

Wind Component ◽

Meteor Radar ◽

The North ◽

Wave Numbers ◽

Central Canada ◽

June July ◽

Abstract Operation

Abstract. Operation of a Meteor Radar (MWR) at Eureka, Ellesmere Island (80° N, 86° W) began in February 2006: this is the location of the Polar Environmental and Atmospheric Research Laboratory (PEARL), operated by the "Canadian Network for the Detection of Atmospheric Change" (CANDAC). The first 36 months of tidal wind data (82–97 km) are here combined with contemporaneous tides from the Meteor Radar (MWR) at Adventdalen, Svalbard (78° N, 16° E), to provide the first significant evidence for interannual variability (IAV) of the High Arctic's diurnal and semidiurnal migrating (MT) and non-migrating tides (NMT). The three-year monthly means for both diurnal (DT) and semi-diurnal (SDT) winds demonstrate significantly different amplitudes and phases at Eureka and Svalbard. Typically the summer-maximizing DT is much larger (~24 m s−1 at 97 km) at Eureka, while the Svalbard tide (5–24 m s−1 at 97 km)) is almost linear (north-south) rather than circular. Interannual variations are smallest in the summer and autumn months. The High Arctic SDT has maxima centred on August/September, followed in size by the winter features; and is much larger at Svalbard (24 m s−1 at 97 km, versus 14–18 m s−1 in central Canada). Depending on the location, the IAV are largest in spring/winter (Eureka) and summer/autumn (Svalbard). Fitting of wave-numbers for the migrating and non-migrating tides (MT, NMT) determines dominant tides for each month and height. Existence of NMT is consistent with nonlinear interactions between migrating tides and (quasi) stationary planetary wave (SPW) S=1 (SPW1). For the diurnal oscillation, NMT s=0 for the east-west (EW) wind component dominates (largest tide) in the late autumn and winter (November–February); and s=+2 is frequently seen in the north-south (NS) wind component for the same months. The semi-diurnal oscillation's NMT s=+1 dominates from March to June/July. There are patches of s=+3 and +1, in the late fall-winter. These wave numbers are also consistent with SPW1-MT interactions. Comparisons for 2007 of the observed DT and SDT at 78–80° N, with those within the Canadian Middle Atmosphere Model Data Assimilation System CMAM-DAS, are a major feature of this paper. The diurnal tides for the two locations have important similarities as observed and modeled, with seasonal maxima in the mesosphere from April to October, and similar phases with long/evanescent wavelengths. However, differences are also significant: observed Eureka amplitudes are generally larger than the model; and at Svalbard the modeled tide is classically circular, rather than anomalous. For the semi-diurnal tide, the amplitudes and phases differ markedly between Eureka and Svalbard for both MWR-radar data and CMAM-DAS data. The seasonal variations from observed and modeled archives also differ at each location. Tidal NMT-amplitudes and wave-numbers for the model differ substantially from observations.

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Metagenomic Analysis of Stress Genes in Microbial Mat Communities from Antarctica and the High Arctic

Applied and Environmental Microbiology ◽

10.1128/aem.06354-11 ◽

2011 ◽

Vol 78 (2) ◽

pp. 549-559 ◽

Cited By ~ 103

Author(s):

Thibault Varin ◽

Connie Lovejoy ◽

Anne D. Jungblut ◽

Warwick F. Vincent ◽

Jacques Corbeil

Keyword(s):

High Arctic ◽

Environmental Stresses ◽

The Arctic ◽

Functional Responses ◽

Protein Coding ◽

Content Type ◽

Stress Genes ◽

Cyanobacterial Genes ◽

Shock Proteins ◽

The Antarctic

ABSTRACTPolar and alpine microbial communities experience a variety of environmental stresses, including perennial cold and freezing; however, knowledge of genomic responses to such conditions is still rudimentary. We analyzed the metagenomes of cyanobacterial mats from Arctic and Antarctic ice shelves, using high-throughput pyrosequencing to test the hypotheses that consortia from these extreme polar habitats were similar in terms of major phyla and subphyla and consequently in their potential responses to environmental stresses. Statistical comparisons of the protein-coding genes showed similarities between the mats from the two poles, with the majority of genes derived fromProteobacteriaandCyanobacteria; however, the relative proportions differed, with cyanobacterial genes more prevalent in the Antarctic mat metagenome. Other differences included a higher representation ofActinobacteriaandAlphaproteobacteriain the Arctic metagenomes, which may reflect the greater access to diasporas from both adjacent ice-free lands and the open ocean. Genes coding for functional responses to environmental stress (exopolysaccharides, cold shock proteins, and membrane modifications) were found in all of the metagenomes. However, in keeping with the greater exposure of the Arctic to long-range pollutants, sequences assigned to copper homeostasis genes were statistically (30%) more abundant in the Arctic samples. In contrast, more reads matching the sigma B genes were identified in the Antarctic mat, likely reflecting the more severe osmotic stress during freeze-up of the Antarctic ponds. This study underscores the presence of diverse mechanisms of adaptation to cold and other stresses in polar mats, consistent with the proportional representation of major bacterial groups.

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High gas-phase mixing ratios of formic and acetic acid in the High Arctic

10.5194/acp-2018-60 ◽

2018 ◽

Author(s):

Emma L. Mungall ◽

Jonathan P. D. Abbatt ◽

Jeremy J. B. Wentzell ◽

Gregory R. Wentworth ◽

Jennifer G. Murphy ◽

...

Keyword(s):

Acetic Acid ◽

Gas Phase ◽

Transport Model ◽

High Arctic ◽

Early Summer ◽

The Arctic ◽

Chemical Transport Model ◽

Phase Measurements ◽

Diurnal Cycles ◽

Mixing Ratios

Abstract. Formic and acetic acid are ubiquitous and abundant in the Earth's atmosphere and are important contributors to cloud water acidity, especially in remote regions. Their global sources are not well understood, as evidenced by the inability of models to reproduce the magnitude of measured mixing ratios, particularly at high northern latitudes. The scarcity of measurements at those latitudes is also a hindrance to understanding these acids and their sources. Here, we present ground-based gas-phase measurements of formic acid (FA) and acetic acid (AA) in the Canadian Arctic collected at 0.5 Hz with a high resolution chemical ionization time-of-flight mass spectrometer using the iodide reagent ion (Iodide HR-ToF-CIMS, Aerodyne). This study was conducted at Alert, Nunavut, in the early summer of 2016. FA and AA mixing ratios for this period show high temporal variability and occasional excursions to very high values (up to 11 and 40 ppbv respectively). High levels of FA and AA were observed under two very different conditions: under overcast, cold conditions during which physical equilibrium partitioning should not favour their emission, and during warm and sunny periods. During the latter, sunny periods, the FA and AA mixing ratios also displayed diurnal cycles in keeping with a photochemical source near the ground. These observations highlight the complexity of the sources of FA and AA, and suggest that current chemical transport model implementations of the sources of FA and AA in the Arctic may be incomplete.

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Density, snow, and seasonality lead to variation in muskox (Ovibos moschatus) habitat selection during summer

Canadian Journal of Zoology ◽

10.1139/cjz-2018-0292 ◽

2019 ◽

Vol 97 (11) ◽

pp. 997-1003

Author(s):

Orlando Tomassini ◽

Floris M. van Beest ◽

Niels M. Schmidt

Keyword(s):

Population Dynamics ◽

Habitat Selection ◽

Environmental Conditions ◽

Census Data ◽

High Arctic ◽

Early Summer ◽

The Arctic ◽

Selection Strategy ◽

Ovibos Moschatus ◽

Arctic Summer

Understanding how environmental conditions influence habitat selection and suitability of free-ranging animals is critical, as the outcome may have implications for individual fitness and population dynamics. Density and snow are among the most influential environmental conditions driving habitat-selection patterns of northern ungulates. We used two decades of census data from high Arctic Greenland to quantify inter- and intra-annual variations in muskox (Ovibos moschatus (Zimmermann, 1780)) habitat selection and suitability during the Arctic summer (July through October). Across years, habitat selection varied considerably, and the strength of habitat selection appeared negatively related to both muskox density and spring snow cover. In early summer, habitat suitability was high and spatially rather uniform. Towards the autumn, suitable habitats contracted to just the lower elevations, when muskoxen exhibited increasingly stronger habitat selection towards low elevations and dense vegetation. This selection strategy clearly reflects the need to build up fat reserves for the upcoming winter, highlighting the energetic importance of the Arctic summer. Extreme climatic events such as freezing rain in autumn are increasing in frequency in Greenland and limit muskox access to high-quality forage in fens. Such events may therefore negatively affect the energy acquisition process of muskox with potential cascading consequences on population dynamics.

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Polar endoliths – an anti-correlation of climatic extremes and microbial biodiversity

International Journal of Astrobiology ◽

10.1017/s1473550403001344 ◽

2002 ◽

Vol 1 (4) ◽

pp. 305-310 ◽

Cited By ~ 22

Author(s):

Charles S. Cockell ◽

Christopher P. McKay ◽

Christopher Omelon

Keyword(s):

Biological Diversity ◽

High Arctic ◽

Physical Structure ◽

Environmental Stresses ◽

The Arctic ◽

Dry Valleys ◽

Freeze Thaw ◽

Devon Island ◽

Order Of Magnitude ◽

The Antarctic

We examined the environmental stresses experienced by cyanobacteria living in endolithic gneissic habitats in the Haughton impact structure, Devon Island, Canadian High Arctic (75° N) and compared them with the endolithic habitat at the opposite latitude in the Dry Valleys of Antarctica (76° S). In the Arctic during the summer, there is a period for growth of approximately 2.5 months when temperatures rise above freezing. During this period, freeze–thaw can occur during the diurnal cycle, but freeze–thaw excursions are rare within higher-frequency temperature changes on the scale of minutes, in contrast with the Antarctic Dry Valleys. In the Arctic location rainfall of approximately 3 mm can occur in a single day and provides moisture for endolithic organisms for several days afterwards. This rainfall is an order of magnitude higher than that received in the Dry Valleys over 1 year. In the Dry Valleys, endolithic communities may potentially receive higher levels of ultraviolet radiation than the Arctic location because ozone depletion is more extreme. The less extreme environmental stresses experienced in the Arctic are confirmed by the presence of substantial epilithic growth, in contrast to the Dry Valleys. Despite the more extreme conditions experienced in the Antarctic location, the diversity of organisms within the endolithic habitat, which includes lichen and eukaryotic algal components, is higher than observed at the Arctic location, where genera of cyanobacteria dominate. The lower biodiversity in the Arctic may reflect the higher water flow through the rocks caused by precipitation and the more heterogeneous physical structure of the substrate. The data illustrate an instance in which extreme climate is anti-correlated with microbial biological diversity.

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Life cycles and population dynamics of enchytraeids (Oligochaeta) from the High Arctic

Canadian Journal of Zoology ◽

10.1139/z00-148 ◽

2000 ◽

Vol 78 (12) ◽

pp. 2079-2086 ◽

Cited By ~ 8

Author(s):

T Birkemoe ◽

S J Coulson ◽

L Sømme

Keyword(s):

Population Dynamics ◽

High Arctic ◽

Early Summer ◽

Life Cycles ◽

The Arctic ◽

Adult Size ◽

Numerous Species ◽

Summer Temperatures ◽

First Time ◽

Mature Size

We report the results of the first study of the population dynamics and life cycles of Arctic enchytraeid populations. Sampling was undertaken in a Salix heath in Adventdalen, Svalbard, during one summer and the succeeding spring. In addition, a Cassiope heath at a more northerly site close to Ny-Ålesund, Svalbard, was sampled twice. The Arctic enchytraeids were generally smaller at maturity than their temperate-zone relatives. The three most numerous species in the Salix heath, Henlea perpusilla, Henlea glandulifera, and Bryodrilus parvus, hatched from cocoons in early summer and attained adult size early in their second summer. A few H. perpusilla and H. glandulifera reached mature size in their first summer; since the summer of investigation was unusually cold, these species may have a 1-year life cycle in warmer years. Life cycles were apparently longer in the Cassiope heath than in the Salix heath. Henlea perpusilla, H. glandulifera, and B. parvus produced eggs throughout the summer in the Salix heath, though hatching was restricted to early summer. Therefore, the hypothesis that cocoons require a cold period to hatch was tested in a laboratory experiment. When soil containing cocoons was incubated at -5°C for 3 weeks, a significant increase in juveniles was demonstrated for H. perpusilla and Bryodrilus diverticulatus compared with soils kept at constant summer temperatures. This is the first time that breaking of dormancy by an external stimulus has been demonstrated in enchytraeid cocoons.

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High gas-phase mixing ratios of formic and acetic acid in the High Arctic

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-10237-2018 ◽

2018 ◽

Vol 18 (14) ◽

pp. 10237-10254 ◽

Cited By ~ 6

Author(s):

Emma L. Mungall ◽

Jonathan P. D. Abbatt ◽

Jeremy J. B. Wentzell ◽

Gregory R. Wentworth ◽

Jennifer G. Murphy ◽

...

Keyword(s):

Acetic Acid ◽

Gas Phase ◽

Transport Model ◽

High Arctic ◽

Early Summer ◽

The Arctic ◽

Chemical Transport Model ◽

Phase Measurements ◽

Diurnal Cycles ◽

Mixing Ratios

Abstract. Formic and acetic acid are ubiquitous and abundant in the Earth's atmosphere and are important contributors to cloud water acidity, especially in remote regions. Their global sources are not well understood, as evidenced by the inability of models to reproduce the magnitude of measured mixing ratios, particularly at high northern latitudes. The scarcity of measurements at those latitudes is also a hindrance to understanding these acids and their sources. Here, we present ground-based gas-phase measurements of formic acid (FA) and acetic acid (AA) in the Canadian Arctic collected at 0.5 Hz with a high-resolution chemical ionization time-of-flight mass spectrometer using the iodide reagent ion (iodide HR-ToF-CIMS, Aerodyne). This study was conducted at Alert, Nunavut, in the early summer of 2016. FA and AA mixing ratios for this period show high temporal variability and occasional excursions to very high values (up to 11 and 40 ppbv respectively). High levels of FA and AA were observed under two very different conditions: under overcast, cold conditions during which physical equilibrium partitioning should not favor their emission, and during warm and sunny periods. During the latter, sunny periods, the FA and AA mixing ratios also displayed diurnal cycles in keeping with a photochemical source near the ground. These observations highlight the complexity of the sources of FA and AA, and suggest that current chemical transport model implementations of the sources of FA and AA in the Arctic may be incomplete.

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Characteristics of Arctic winds at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

Annales Geophysicae ◽

10.5194/angeo-29-1927-2011 ◽

2011 ◽

Vol 29 (10) ◽

pp. 1927-1938 ◽

Cited By ~ 5

Author(s):

A. H. Manson ◽

C. E. Meek ◽

X. Xu ◽

T. Aso ◽

J. R. Drummond ◽

...

Keyword(s):

Middle Atmosphere ◽

Polar Vortex ◽

High Arctic ◽

The Arctic ◽

Short Term ◽

Meridional Winds ◽

The Mean ◽

Abstract Operation ◽

Data Assimilation System

Abstract. Operation of a Meteor Wind Radar (MWR) at Eureka, Ellesmere Island (80° N, 86° W) began in February 2006; this is the location of the Polar Environmental and Atmospheric Research Laboratory (PEARL), operated by the "Canadian Network for the Detection of Atmospheric Change" (CANDAC). The first 36 months of wind data (82–97 km) are here combined with contemporaneous winds from the Meteor Wind Radar at Adventdalen, Svalbard (78° N, 16° E), to provide the first evidence for substantial interannual variability (IAV) of longitudinally spaced observations of mean/background winds and waves at such High Arctic latitudes. The influences of "Sudden Stratospheric Warmings" (SSW) are also apparent. Monthly meridional (north-south, NS) 3-year means for each location/radar demonstrate that winds (82–97 km) differ significantly between Canada and Norway, with winter-equinox values generally northward over Eureka and southward over Svalbard. Using January 2008 as case study, these oppositely directed meridional winds are related to mean positions of the Arctic mesospheric vortex. The vortex is from the Canadian Middle Atmosphere Model, with its Data Assimilation System (CMAM-DAS). The characteristics of "Sudden stratospheric Warmings" SSW in each of the three winters are noted, as well as their uniquely distinctive short-term mesospheric wind disturbances. Comparisons of the mean winds over 36 months at 78 and 80° N, with those within CMAM-DAS, are featured. E.g. for 2007, while both monthly mean EW and NS winds from CMAM/radar are quite similar over Eureka (82–88 km), the modeled autumn-winter NS winds over Svalbard (73–88 km) differ significantly from observations. The latter are southward, and the modeled winds over Svalbard are predominately northward. The mean positions of the winter polar vortex are related to these differences.

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Summer phytoplankton of the northern Barents Sea (75–80º N)

Hydrosphere Еcology (Экология гидросферы) ◽

10.33624/2587-9367-2019-2(4)-8-19 ◽

2019 ◽

pp. 8-19

Author(s):

Larisa A. Pautova ◽

Vladimir A. Silkin ◽

Marina D. Kravchishina ◽

Valeriy G. Yakubenko ◽

Anna L. Chultsova

Keyword(s):

Barents Sea ◽

Weighted Average ◽

Arctic Basin ◽

High Arctic ◽

Alexandrium Tamarense ◽

Warm Water ◽

The Arctic ◽

Absolute Maximum ◽

Deep Trench ◽

Maximum Biomass

The structure of the summer planktonic communities of the Northern part of the Barents sea in the first half of August 2017 were studied. In the sea-ice melting area, the average phytoplankton biomass producing upper 50-meter layer of water reached values levels of eutrophic waters (up to 2.1 g/m3). Phytoplankton was presented by diatoms of the genera Thalassiosira and Eucampia. Maximum biomass recorded at depths of 22–52 m, the absolute maximum biomass community (5,0 g/m3) marked on the horizon of 45 m (station 5558), located at the outlet of the deep trench Franz Victoria near the West coast of the archipelago Franz Josef Land. In ice-free waters, phytoplankton abundance was low, and the weighted average biomass (8.0 mg/m3 – 123.1 mg/m3) corresponded to oligotrophic waters and lower mesotrophic waters. In the upper layers of the water population abundance was dominated by small flagellates and picoplankton from, biomass – Arctic dinoflagellates (Gymnodinium spp.) and cold Atlantic complexes (Gyrodinium lachryma, Alexandrium tamarense, Dinophysis norvegica). The proportion of Atlantic species in phytoplankton reached 75%. The representatives of warm-water Atlantic complex (Emiliania huxleyi, Rhizosolenia hebetata f. semispina, Ceratium horridum) were recorded up to 80º N, as indicators of the penetration of warm Atlantic waters into the Arctic basin. The presence of oceanic Atlantic species as warm-water and cold systems in the high Arctic indicates the strengthening of processes of “atlantificacion” in the region.

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Characterization of Transport Regimes and the Polar Dome during Arctic Spring and Summer using in-situ Aircraft Measurements

10.5194/acp-2019-70 ◽

2019 ◽

Cited By ~ 3

Author(s):

Heiko Bozem ◽

Peter Hoor ◽

Daniel Kunkel ◽

Franziska Köllner ◽

Johannes Schneider ◽

...

Keyword(s):

Lower Troposphere ◽

High Arctic ◽

The Arctic ◽

Trace Gas ◽

Second Phase ◽

Aerosol Formation ◽

Transport Barrier ◽

Data Set ◽

Air Masses ◽

Mixing Ratios

Abstract. The springtime composition of the Arctic lower troposphere is to a large extent controlled by transport of mid-latitude air masses into the Arctic, whereas during the summer precipitation and natural sources play the most important role. Within the Arctic region, there exists a transport barrier, known as the polar dome, which results from sloping isentropes. The polar dome, which varies in space and time, exhibits a strong influence on the transport of air masses from mid-latitudes, enhancing it during winter and inhibiting it during summer. Furthermore, a definition for the location of the polar dome boundary itself is quite sparse in the literature. We analyzed aircraft based trace gas measurements in the Arctic during two NETCARE airborne field camapigns (July 2014 and April 2015) with the Polar 6 aircraft of Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (AWI), Bremerhaven, Germany, covering an area from Spitsbergen to Alaska (134° W to 17° W and 68° N to 83° N). For the spring (April 2015) and summer (July 2014) season we analyzed transport regimes of mid-latitude air masses travelling to the high Arctic based on CO and CO2 measurements as well as kinematic 10-day back trajectories. The dynamical isolation of the high Arctic lower troposphere caused by the transport barrier leads to gradients of chemical tracers reflecting different local chemical life times and sources and sinks. Particularly gradients of CO and CO2 allowed for a trace gas based definition of the polar dome boundary for the two measurement periods with pronounced seasonal differences. For both campaigns a transition zone rather than a sharp boundary was derived. For July 2014 the polar dome boundary was determined to be 73.5° N latitude and 299–303.5 K potential temperature, respectively. During April 2015 the polar dome boundary was on average located at 66–68.5° N and 283.5–287.5 K. Tracer-tracer scatter plots and probability density functions confirm different air mass properties inside and outside of the polar dome for the July 2014 and April 2015 data set. Using the tracer derived polar dome boundaries the analysis of aerosol data indicates secondary aerosol formation events in the clean summertime polar dome. Synoptic-scale weather systems frequently disturb this transport barrier and foster exchange between air masses from midlatitudes and polar regions. During the second phase of the NETCARE 2014 measurements a pronounced low pressure system south of Resolute Bay brought inflow from southern latitudes that pushed the polar dome northward and significantly affected trace gas mixing ratios in the measurement region. Mean CO mixing ratios increased from 77.9 ± 2.5 ppbv to 84.9 ± 4.7 ppbv from the first period to the second period. At the same time CO2 mixing ratios significantly dropped from 398.16 ± 1.01 ppmv to 393.81 ± 2.25 ppmv. We further analysed processes controlling the recent transport history of air masses within and outside the polar dome. Air masses within the spring time polar dome mainly experienced diabatic cooling while travelling over cold surfaces. In contrast air masses in the summertime polar dome were diabatically heated due to insolation. During both seasons air masses outside the polar dome slowly descended into the Arctic lower troposphere from above caused by radiative cooling. The ascent to the middle and upper troposphere mainly took place outside the Arctic, followed by a northward motion. Our results demonstrate the successful application of a tracer based diagnostic to determine the location of the polar dome boundary.

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