Recent trends of spatial extent and volume of global snow and icecover are reported the A. examines expected changes projected for increasing concentrations of greenhouse gases too.
Evidence of recent changes in global snow and icecover in Global Change.
Data on recent variations in the seasonal extent of snow cover and sea ice, of the terminal position and volume of alpine glaciers, and of ground temperature profiles in permafrost area are reviewed.
Illustration of the roles of snow in the evolution of the winter cover of a lake
Spatial patterns in the snow and icecover of Elizabeth Lake, Labrador, as surveyed in late February 1979, are displayed and analysed. Relationships between distinct trends in the ice and less distinct trends in the snow are discussed within
a context of processes operative during a winter. The nature of and spatial patterns in the winter cover of lakes and their evolution have important implications for those interested in generalizing about lake ice properties and about the effects of snow
Continental ice sheets and the planetary radiation budget
this interaction in a quantitative way. Experiments in which the ice-sheet model is coupled step by step to the climate model show that ice sheets hardly affect the zonal mean radiation balance because the albedo feedback due to sea ice and snow cover is dominating
The interaction between continental ice sheets and the planetary radiation budget is potentially important in climate-sensitivity studies. A simple ice-sheet model incorporated in an energy-balance climate model provides a tool for studying
. The model requires a 5% drop in the solar constant to create ice sheets of ice-age size. If the feedback between surface elevation and ice-mass balance is included (in very crude way), the ice-sheet size (L, mesured southward from 70N) becomes much more
sensitive to insolation. For a range of normalized solar constants, roughly from 0.98 to 1.02, two stable solutions exist: L0 and L2000 km. This result demonstrates that the response of ice sheets to insolation variations is far from linear. It also stresses
the need for explicit modeling of the ice-mass balance of ice sheets, particularly its dependence on surface elevation.
In this study, flume experiments of flows under a simulated icecover are presented. Open water conditions and simulated rough ice-covered flows are discussed. Mean flow and turbulent flow statistics were obtained from an Acoustic Doppler
Velocimeter (ADV) above a gravel-bed surface. A central region of faster flow develops in the middle portion of the flow with the addition of a rough cover. The turbulent flow characteristics are unambiguously different when simulated icecovered conditions
are used. Two distinct boundary layers (near the bed and in the vicinity of the icecover, near the water surface) are clearly identified, each being characterized by high turbulent intensity levels. Detailed profile measurements of Reynolds stresses
and turbulent kinetic energy indicate that the turbulence structure is strongly influenced by the presence of an icecover and its roughness characteristics.
Anchor ice ; Antarctica ; Arctic Region ; Frazil ice ; Ice ; Icecover ; Polar region ; Sea ice
This paper reviews the current understanding of anchor ice formation in polar marine environments. Supercooled water is a necessity for anchor ice to form and frazil adhesion is the most likely common mechanism for initial anchor ice growth. Strong
biological zonation has led some authors to suggest that anchor ice does not form to depths of greater than 33 m, yet in Antarctica there appear to be no physical reasons for such a limit given the production of supercooled water to substantial depths
associated with ice shelves. Future work should focus on the potential extent of anchor ice production and identify the key oceanographic, glaciological and meteorological conditions conducive to its formation.
This paper discusses a technique for mapping the area coverage of sea ice regardless of a cloud cover. Data from the AVHRR sensor of the NOAA-9 satellite were recorded on 22 May 1988.
The AA. compare macroturbulent coherent structures (MCS) geometry and organization between icecovered and open channel flow conditions. Velocity profiles were obtained using a Pulse-Coherent Acoustic Doppler Profiler in both open channel and ice
-covered conditions. A field survey was carried out in early March 2008 in a small meandering reach of the Neigette River, which is part of the catchment system of the Mitis River, Quebec. The friction imposed by the icecover results in parabolic shaped
velocity profiles. Reynolds stresses in the streamwise (u) and vertical (v) components of the flow show positive values near the channel bed and negative values near the icecover, with 2 distinctive boundary layers with specific turbulent signatures
discontinued and nested close to the boundary walls in ice-covered conditions.
The parameterization of surface albedo for sea ice and its snow cover
Albedo ; Antarctica ; Arctic Region ; Atmospheric circulation ; Canada ; Cold area ; Model ; Northwest Territories ; Radiation ; Remote sensing ; Sea ice ; Snow cover
The factors determining the albedo of sea ice and its snow cover, including spectral characteristics are reviewed. The thickness, properties and fractional cover of snow are of general importance. The effects of sky conditions and surface impurities
Ross ice shelf oxygen isotopes and West Antarctic climate history
Antarctique ; Barrière de Ross ; Carotte de glace ; Glace ; Géographie des régions polaires ; Isotopes de l'oxygène ; Paléoclimatologie ; Quaternaire supérieur ; Ross Ice Shelf
The Ross Ice Shelf oxygen isotopic profile at station J-9 covers at least the last 30,000 yr.
Palaeo-ice-stream onsets : examples from the north-eastern Laurentide Ice Sheet
Reconstructing ice-sheet dynamics from subglacial sediments and landforms. Special issue
Arctic Region ; Baffin Land ; Canada ; Cold area ; Geographical information system ; Glacial features ; Ice sheet ; LANDSAT ; Moraine ; Northwest Territories ; Palaeogeography ; Remote sensing ; Thematic Mapper
of north-eastern Canada formerly covered by the Laurentide Ice Sheet. Four different cases are considered and analysed in a geographical information system (GIS) environment with full integration of ancillary topographical and geological data. The AA
The AA. report on observations of glacial landscapes at the head of geomorphologically interpreted palaeo-ice streams, i.e. palaeo-ice-stream onsets. Their work is based on the results of systematic palaeoglaciological mapping of the portion
. conclude that conditions for the preservation of the onset zones are more likely to be met in the case of relatively small ice streams because these are more rapidly deglaciated.
Glacial features ; Ice sheet;Ice cap;Inlandsis ; Quaternary ; Salt tectonics ; United States
of the salt-bearing bed has been overridden by massive ice sheets. From central New York through northeastern Ohio, southwestern Ohio, and the southern peninsula of Michigan, up-dip edges of salt basins are in areas covered by successive Pleistocene ice sheets.
Evaluation of remote sensing techniques for ice-area classification applied to the tropical Quelccaya Ice Cap, Peru
Andes ; Classification ; Deglaciation ; Glacier ; Icecover ; Peru ; Remote sensing ; Satellite imagery
La déglaciation des Andes nécessite l'étude de méthodes pour déterminer l'importance de la glace des glaciers à partir d'images par satellite. Plusieurs techniques pour décrire l'englacement sont évaluées au travers de l'application au Quelccaya Ice
The AA. provide a summary of the current state of knowledge pertaining to the geophysical, thermodynamic and dielectric properties of snow on sea ice. They first give a detailed description of snow thermophysical properties such as thermal
conductivity, diffusivity and specific heat and how snow geophysical /electrical properties and the seasonal surface energy balance affect them. The AA. also review the different microwave emission and scattering mechanisms associated with snow-covered first
-year sea ice. Finally, they discuss the annual evolution of the Arctic system through snow thermodynamic and aeolian processes, with linkages to microwave remote sensing.
the ice phenomena : date of the appearance of the first ice, the maximum ice thickness, the frequency of their occurence, the trends, and some phenomena of icecovers deformation on. The observations mainly originate from the period of 1960/61 - 1999/2000
The aim of the present paper is to describe the spatial and temporal diversification of ice characteristics concerning. The observations were carried out in Jamno, Bukowo, Gardno and Łebsco lakes. Characterized were the following features concerning