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  • 1
    Online Resource
    Online Resource
    International Glaciological Society ; 1990
    In:  Annals of Glaciology Vol. 14 ( 1990), p. 9-12
    In: Annals of Glaciology, International Glaciological Society, Vol. 14 ( 1990), p. 9-12
    Abstract: With an airborne lidar, we have observed massive plumes of condensate particles rising from wintertime leads in the Arctic Ocean. Some of these plumes reached an altitude of 4 km; some extended over 200 km down-wind from their surface source. Here we invert the lidar equation and use lidar backscatter data to infer particle concentrations within two such plumes. Assuming that the plumes consist of supercooled water droplets of radius 5 μm, we estimate typical concentrations of 3–6 × 10 5 droplets m -3 just above the leads. Concentrations within the plumes can still be as high as 10 4 droplets m -3 at an altitude of 3 km and 200 km down-wind from some leads. Had we assumed that the plume particles are ice spheres of radius 40 μm, concentrations would be just 100 times less than these.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1990
    detail.hit.zdb_id: 625468-8
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    International Glaciological Society ; 1989
    In:  Annals of Glaciology Vol. 12 ( 1989), p. 9-15
    In: Annals of Glaciology, International Glaciological Society, Vol. 12 ( 1989), p. 9-15
    Abstract: New data on leads and surface-melt phenomena in the Arctic, based on mapping of DMSP visible images, are presented. Lead orientations in the Beaufort Sea are broadly correlated with geostrophic wind direction and show similar synoptic scale patterns. Preliminary results of airborne 1.06 μm lidar transects over Baffin Bay demonstrate its great potential for high-resolution mapping of open-water areas and, in winter/spring, their ice-crystal plumes. Some of these sub-visible plumes are observed to penetrate the Arctic inversion. Snow-melt maps for the entire Arctic prepared for four summer seasons have been used to derive surface-albedo data. From these data the variability of the surface-energy balance is estimated to be equivalent to 0.6 m of ice melt.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1989
    detail.hit.zdb_id: 625468-8
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    International Glaciological Society ; 1989
    In:  Annals of Glaciology Vol. 12 ( 1989), p. 9-15
    In: Annals of Glaciology, International Glaciological Society, Vol. 12 ( 1989), p. 9-15
    Abstract: New data on leads and surface-melt phenomena in the Arctic, based on mapping of DMSP visible images, are presented. Lead orientations in the Beaufort Sea are broadly correlated with geostrophic wind direction and show similar synoptic scale patterns. Preliminary results of airborne 1.06 μm lidar transects over Baffin Bay demonstrate its great potential for high-resolution mapping of open-water areas and, in winter/spring, their ice-crystal plumes. Some of these sub-visible plumes are observed to penetrate the Arctic inversion. Snow-melt maps for the entire Arctic prepared for four summer seasons have been used to derive surface-albedo data. From these data the variability of the surface-energy balance is estimated to be equivalent to 0.6 m of ice melt.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1989
    detail.hit.zdb_id: 625468-8
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Online Resource
    Online Resource
    International Glaciological Society ; 1990
    In:  Annals of Glaciology Vol. 14 ( 1990), p. 9-12
    In: Annals of Glaciology, International Glaciological Society, Vol. 14 ( 1990), p. 9-12
    Abstract: With an airborne lidar, we have observed massive plumes of condensate particles rising from wintertime leads in the Arctic Ocean. Some of these plumes reached an altitude of 4 km; some extended over 200 km down-wind from their surface source. Here we invert the lidar equation and use lidar backscatter data to infer particle concentrations within two such plumes. Assuming that the plumes consist of supercooled water droplets of radius 5 μm, we estimate typical concentrations of 3–6 × 10 5 droplets m -3 just above the leads. Concentrations within the plumes can still be as high as 10 4 droplets m -3 at an altitude of 3 km and 200 km down-wind from some leads. Had we assumed that the plume particles are ice spheres of radius 40 μm, concentrations would be just 100 times less than these.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1990
    detail.hit.zdb_id: 625468-8
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
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  • 5
    In: Journal of Glaciology, International Glaciological Society, Vol. 60, No. 221 ( 2014), p. 537-552
    Abstract: The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority was given to completeness of coverage, but a limited, uniform set of attributes is attached to each of the ~198 000 glaciers in its latest version, 3.2. Satellite imagery from 1999–2010 provided most of the outlines. Their total extent is estimated as 726 800 ± 34 000 km 2 . The uncertainty, about ±5%, is derived from careful single-glacier and basin-scale uncertainty estimates and comparisons with inventories that were not sources for the RGI. The main contributors to uncertainty are probably misinterpretation of seasonal snow cover and debris cover. These errors appear not to be normally distributed, and quantifying them reliably is an unsolved problem. Combined with digital elevation models, the RGI glacier outlines yield hypsometries that can be combined with atmospheric data or model outputs for analysis of the impacts of climatic change on glaciers. The RGI has already proved its value in the generation of significantly improved aggregate estimates of glacier mass changes and total volume, and thus actual and potential contributions to sea-level rise.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 2014
    detail.hit.zdb_id: 242506-3
    detail.hit.zdb_id: 2140541-4
    SSG: 14
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    International Glaciological Society ; 2016
    In:  Annals of Glaciology Vol. 57, No. 71 ( 2016-03), p. 212-222
    In: Annals of Glaciology, International Glaciological Society, Vol. 57, No. 71 ( 2016-03), p. 212-222
    Abstract: Air temperature is a key control of processes affecting snow and glaciers in high-elevation catchments, including melt, snowfall and sublimation. It is therefore a key input variable to models of land–surface–atmosphere interaction. Despite this importance, its spatial variability is poorly understood and simple assumptions are made to extrapolate it from point observations to the catchment scale. We use a dataset of 2.75 years of air temperature measurements (from May 2012 to November 2014) at a network of up to 27 locations in the Langtang River, Nepal, catchment to investigate air temperature seasonality and consistency between years. We use observations from high elevations and from the easternmost section of the basin to corroborate previous findings of shallow lapse rates. Seasonal variability is strong, with shallowest lapse rates during the monsoon season. Diurnal variability is also strong and should be taken into account since processes such as melt have a pronounced diurnal variability. Use of seasonal lapse rates seems crucial for glacio-hydrological modelling, but seasonal lapse rates seem stable over the 2–3 years investigated. Lateral variability at transects across valley is high and dominated by aspect, with south-facing sites being warmer than north-facing sites and deviations from the fitted lapse rates of up to several degrees. Local factors (e.g. topographic shading) can reduce or enhance this effect. The interplay of radiation, aspect and elevation should be further investigated with high-elevation transects.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 2016
    detail.hit.zdb_id: 625468-8
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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