| Titre | Comparison of the influence of coastal proximity on ground thermal regimes at two High Arctic sites |
| Auteur | Bonnaventure, P P; Smith, S L; Lewkowicz, A G |
| Source | Arctic Net Annual Science Meeting 2016; 2016 p. 23-24 |
| Liens | Online - En ligne
|
| Année | 2016 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20160232 |
| Éditeur | Arctic Net |
| Réunion | Arctic Net Annual Science Meeting 2016; Winnipeg, MB; CA; décembre 5-9 2016 |
| Document | livre |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Nunavut |
| SNRC | 120E; 340B |
| Lat/Long OENS | -86.0000 -84.0000 80.8333 80.0000 |
| Lat/Long OENS | -64.0000 -61.8333 82.7500 82.0000 |
| Sujets | pergélisol; regimes thermiques; températures au sol; congélation du sol; trous de mine; milieu côtièr; climat arctique; pédologie |
| |
| Programme | Surveillance des variables climatiques, Géosciences de changements climatiques |
| Résumé | (disponible en anglais seulement)
Air 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. |
| Résumé | (Résumé en langage clair et simple, non publié)
Les résultats d'études sur l'impact de la proximité du littoral sur l'état thermique du pergélisol dans l'Arctique canadien seront présentés. Les
données de température de l'air et du sol obtenues à deux sites sur l'île d'Ellesmere NU, soit Eureka et Alert, ont été utilisées afin de démontrer que, jusqu'à une distance d'au moins 5km, les températures annuelles moyennes de l'air et du
pergélisol augmentent en direction de l'intérieur des terres. Des inversions persistantes dans les températures de l'air peuvent se développer pendant les mois froids de l'hiver, ce qui mène à des conditions plus froides aux sites de faible altitude,
par rapport à ceux de plus haute altitude. De meilleures informations sur les variations de température de l'air et du pergélisol en fonction de la distance de la côte faciliteront des avancées dans les modèles régionaux de conditions du pergélisol.
Ces informations aideront aussi à déterminer si le pergélisol des régions côtières et celui à l'intérieur des terres se réchauffent à des vitesses différentes en réponse au changement climatique. Une meilleure compréhension des conditions actuelles
de pergélisol ainsi que des prévisions de conditions futures aideront à la prise de décisions éclairées en matière de planification de l'adaptation dans une région où l'on s'attend à ce que le climat change plus rapidement que d'autres
régions. |
| GEOSCAN ID | 299349 |
|
|