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TitleComparison of the influence of coastal proximity on ground thermal regimes at two High Arctic sites
AuthorBonnaventure, P P; Smith, S L; Lewkowicz, A G
SourceArctic Net Annual Science Meeting 2016; 2016 p. 23-24
Year2016
Alt SeriesEarth Sciences Sector, Contribution Series 20160232
PublisherArctic Net
MeetingArctic Net Annual Science Meeting 2016; Winnipeg, MB; CA; December 5-9 2016
Documentbook
Lang.English
Mediaon-line; digital
File formatpdf
ProvinceNunavut
NTS120E; 340B
AreaEllesmere Island
Lat/Long WENS -86.0000 -84.0000 80.8333 80.0000
Lat/Long WENS -64.0000 -61.8333 82.7500 82.0000
Subjectssoils science; permafrost; thermal regimes; ground temperatures; freezing ground; boreholes; coastal environment; climate, arctic
ProgramEssential Climate Variable Monitoring, Climate Change Geoscience
LinksOnline - En ligne
AbstractAir and ground temperature data collected at Canadian Forces Station Alert (82°N, 62°W) and in the vicinity of Eureka (80°N, 86°W) on Ellesmere Island in Nunavut have been analyzed to investigate the potential role that air temperature inversions play in influencing the spatial variation of permafrost thermal conditions in coastal areas of the High Arctic. In both locations frequent and persistent air temperature inversions have been documented using a series of weather stations and instrumented boreholes deployed along an elevation gradient. At the Eureka site the weather stations also extend further inland (up to 5 km) compared to Alert (2.3 km). During inversion periods, which may last several days, air temperatures in the valley bottoms at lower elevations can be considerably colder than adjacent stations located at higher elevations and distances from the coast.
At Eureka air temperatures increased away from the coast on an annual and seasonal basis with mean annual temperatures increasing logarithmically inland by 1.6°C from -17.2°C to -15.6°C. Mean annual ground surface temperatures varied from -13.3°C to -14.3°C but did not show a consistent trend inland on either an annual or a seasonal basis, likely due to spatially variable distribution of snow along the transect. There was however, a trend inland in mean ground temperatures at 0.5 m and 5 m depths, which increased inland by up to 3°C and 1.1°C respectively. At Alert similar patterns were observed. Ground temperatures were highest at the lowest elevation site at the coast with a mean annual ground temperature of -11.5°C at a depth of 24 m which is close to the zero annual amplitude depth. This site also receives the greatest amount of snow compared to the other four sites located further inland, complicating the impact of the inversion on the spatial heterogeneity of permafrost temperature. However, at sites further inland with little snow cover, ground temperatures are lower in the valley bottom located compared to a site at higher elevation on the valley wall. Calculated TTOP (temperature at the top of permafrost) values for the Alert sites indicate that the occurrence of air temperature inversions during the winter combined with the variable snow cover explain the observed of ground thermal patterns seen at Alert. We conclude that both air and ground temperatures increase inland at least up to 5 km around the Eureka area according to the logarithm of the distance from the coast. This analysis shows that air temperature inversions can produce considerable heterogeneity in the thermal field in the air and in depth across High Arctic landscapes.
Summary(Plain Language Summary, not published)
Results from investigations on the impact of coastal proximity on permafrost thermal state in the Canadian Arctic will be presented. Air and ground temperature data from permafrost observatories for two sites on Ellesmere Island NU, Eureka and Alert were utilized to show that annual mean air and permafrost temperatures were found to increase inland, at least to a distance of 5 km. During the cold winter months, persistent air temperature inversions may develop resulting in colder conditions at lower elevation sites, compared to those at higher elevation. Improved information regarding how air and permafrost temperatures vary with distance from the coast will facilitate better models of regional permafrost conditions and help to determine whether permafrost in coastal and inland areas will warm at different rates in response to climate change. Improved understanding of current permafrost conditions and predictions of future conditions will support informed adaptation planning in a region where climate is expected to change faster than other regions.
GEOSCAN ID299349