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  • 1
    Online Resource
    Online Resource
    Informa UK Limited ; 2002
    In:  La Houille Blanche Vol. 88, No. 6-7 ( 2002-10-01), p. 92-97
    In: La Houille Blanche, Informa UK Limited, Vol. 88, No. 6-7 ( 2002-10-01), p. 92-97
    Type of Medium: Online Resource
    ISSN: 0018-6368 , 1958-5551
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2002
    detail.hit.zdb_id: 3101096-9
    detail.hit.zdb_id: 2410181-3
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  • 2
    Online Resource
    Online Resource
    International Glaciological Society ; 2002
    In:  Annals of Glaciology Vol. 34 ( 2002), p. 58-64
    In: Annals of Glaciology, International Glaciological Society, Vol. 34 ( 2002), p. 58-64
    Abstract: We evaluated the contribution of Special Sensor Microwave/Imager (SSM/I) passive-microwave data to the monitoring of spatial and temporal variability of snow cover in the Churchill area, Manitoba, Canada. Because of the coarse spatial resolution of current passive-microwave sensors, the estimation of snow water equivalent using empirical equations with these instruments is largely compromised in complex areas such as Churchill (forest–tundra ecotone). However, with its high frequency of observations and the availability of a long time series (1988–99), passive-microwave data from the SSM/I radiometer remain a very valuable tool for monitoring the temporal evolution of snow cover at various spatial scales. Through winter 1997/98, we first examined the passive-microwave signatures at the local scale and we identified the major stages of the snow period. Principal-component analysis (PCA) applied on spectral-difference (T b (19H) - T b (37H))time series (1988–99) enabled us to identify spatio-temporal effects over a large area. PCA also permitted the extraction of indices of relevance for monitoring climatic variability and climate change (annual snow-cover duration, dates of snow-cover appearance and disappearance).
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 2002
    detail.hit.zdb_id: 2122400-6
    SSG: 14
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  • 3
    Online Resource
    Online Resource
    UiT The Arctic University of Norway ; 2004
    In:  Rangifer Vol. 24, No. 1 ( 2004-04-01), p. 31-50
    In: Rangifer, UiT The Arctic University of Norway, Vol. 24, No. 1 ( 2004-04-01), p. 31-50
    Abstract: Habitat studies are essential in order to understand the dynamics of migratory caribou herds and to better define management strategies. In this paper, multi-date Landsat images are used to map lichen in the summer range of the George River Caribou Herd (GRCH), Québec-Labrador (Canada), over the period from 1976 to 1998. Multi-Spectral Scanner scenes from the seventies and Thematic Mapper scenes from the eighties and nineties were radiometrically normalized and processed using spectral mixture analysis to produce lichen fraction maps and lichen change maps. Field sites, surveyed during summer campaigns in 2000 and 2001, are used to validate the lichen maps. Results show a good agreement between field data and the lichen results obtained from image analysis. Maps are then interpreted in the context of previous caribou dynamics and habitat studies conducted in the study area over the last three decades. The remote-sensing results confirm the habitat degradation and herd distribution patterns described by other investigators. The period between 1976-1979 and 1985-1986 is characterized by a localized decrease in lichen cover in the southern part of the study area, whereas from 1985-1986 to 1998 the decrease in lichen cover extends northward and westward. This period coincides with the widest extent of the GRCH summer range and activity. The approach presented in this paper provides a valuable means for better understanding the spatio-temporal relation between herd dynamics and distribution, as well as habitat use. Satellite remote sensing imagery is a useful data source, providing timely information over vast and remote territories where caribou populations cannot be surveyed and managed on a frequent basis. 
    Type of Medium: Online Resource
    ISSN: 1890-6729
    Language: Unknown
    Publisher: UiT The Arctic University of Norway
    Publication Date: 2004
    detail.hit.zdb_id: 2439500-6
    detail.hit.zdb_id: 2724077-0
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  • 4
    Online Resource
    Online Resource
    Wiley ; 2002
    In:  Hydrological Processes Vol. 16, No. 8 ( 2002-06-15), p. 1631-1644
    In: Hydrological Processes, Wiley, Vol. 16, No. 8 ( 2002-06-15), p. 1631-1644
    Abstract: Results from an investigation on the evaluation of RADARSAT (C‐HH) imagery for monitoring ice growth and decay, and related processes of shallow sub‐Arctic (tundra and forest) lakes in northern Manitoba, Canada, are presented. Field observations on the structural and stratigraphic characteristics of snow and ice from four lake sites are used in support of the interpretation of changes in synthetic aperture radar backscatter intensity as a function of time and incidence angle (20–49°). Results show that bubble inclusions, most of which are tubular and oriented in the direction of growth, strongly influence backscatter intensity from floating ice in RADARSAT Standard beam mode imagery. It is shown that radar return can vary considerably as a function of incidence angle. Differences of as much as 6·5 dB were observed for the same ice cover when observed at steeper (20–35°) compared with shallower (35–49°) incidence angles. During the early stages of ice growth and/or when the ice volume contains a small amount of tubular bubbles, backscatter intensity from the floating ice measured at shallower incidence angles (35–49°) is similar to that observed from the grounded ice at any incidence angle (−17 to −11 dB). A strong decrease in backscatter was observed at all sites during spring thaw and was explained by the microwave signal being absorbed by the wet snow cover and by specular reflection from the standing water (ponds) on the lake ice surface. With its multiple beam mode configurations, RADARSAT offers an improved temporal coverage over ERS‐1/2, thus making it possible to determine more precisely freeze‐up and break‐up dates, and timing of bottom freezing from shallow Arctic and sub‐Arctic lakes. Copyright © 2002 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 0885-6087 , 1099-1085
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1479953-4
    SSG: 14
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  • 5
    Online Resource
    Online Resource
    Wiley ; 2002
    In:  Hydrological Processes Vol. 16, No. 18 ( 2002-12-30), p. 3691-3706
    In: Hydrological Processes, Wiley, Vol. 16, No. 18 ( 2002-12-30), p. 3691-3706
    Abstract: A one‐dimensional thermodynamic lake ice model (Canadian Lake Ice Model or CLIMo) is used to simulate ice phenology on Great Slave Lake (GSL) in the Mackenzie River basin, Northwest Territories, Canada. Model simulations are validated against freeze‐up and break‐up dates, as well as ice thickness and on‐ice snow depth measurements made in situ at three sites on GSL (Back Bay near Yellowknife, 1960–91; Hay River, 1965–91; Charlton Bay near Fort Reliance, 1977–90). Freeze‐up and break‐up dates from the lake ice model are also compared with those derived from SSM/I 85 GHz passive microwave imagery over the entire lake surface (1988–99). Results show a very good agreement between observed and simulated ice thickness and freeze‐up/break‐up dates over the 30–40 years of observations, particularly for the Back Bay and Hay River sites. CLIMo simulates the ice thickness and annual freeze‐up/break‐dates with a mean error of 7 cm and 4 days respectively. However, some limitations have been identified regarding the rather simplistic approach used to characterize the temporal evolution of snow cover on ice. Future model improvements will therefore focus on this particular aspect, through linkage or coupling to a snow model. Copyright © 2002 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 0885-6087 , 1099-1085
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1479953-4
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  • 6
    Online Resource
    Online Resource
    Wiley ; 2003
    In:  Hydrological Processes Vol. 17, No. 17 ( 2003-12-15), p. 3465-3483
    In: Hydrological Processes, Wiley, Vol. 17, No. 17 ( 2003-12-15), p. 3465-3483
    Type of Medium: Online Resource
    ISSN: 0885-6087 , 1099-1085
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2003
    detail.hit.zdb_id: 1479953-4
    SSG: 14
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  • 7
    Online Resource
    Online Resource
    Wiley ; 2002
    In:  Hydrological Processes Vol. 16, No. 18 ( 2002-12-30), p. 3707-3722
    In: Hydrological Processes, Wiley, Vol. 16, No. 18 ( 2002-12-30), p. 3707-3722
    Abstract: The Canadian government has been compiling various observations on freshwater and coastal sea ice conditions for many years. However, the records are not easily accessible and are dispersed within different government departments. Given this, a major effort was undertaken in order to gather all available observations into a common database—the Canadian Ice Database (CID). This database will respond to the needs for climate monitoring in Canada, the validation and improvement of numerical ice models and the development of new remote‐sensing methods. Indeed, several studies have shown that freshwater ice and sea ice are good proxy indicators of climate variability and change. The first version of CID contains in situ observations from 757 sites distributed across Canada, which were originally kept on digital or paper records at the Meteorological Service of Canada Headquarters and the Canadian Ice Service (CIS). The CID holds 63 546 records covering the period from ice season 1822–23 to 2000–01. An analysis of the database allows one to trace the temporal evolution of the ice networks. The freeze‐up/break‐up network of 2000–01 only represents 4% of what it was in 1985–86. A drastic decline of the ice thickness and the snow on ice network is also observable. In 1997–98, it represented only 10% of the network that existed in 1984–85. The major budget cuts in Canadian government agencies during the late 1980s and the 1990s offer the most plausible explanation for the drastic decline in the ice observation networks. Weekly ice coverage determination on large lakes from satellite imagery by the CIS and the national volunteer ice monitoring program, IceWatch, may provide a means of reviving, at least, the freeze‐up/break‐up network. Copyright © 2002 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 0885-6087 , 1099-1085
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1479953-4
    SSG: 14
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