Developing an understanding of how ice sheets are changing over time requires precise measurements of
the thickness of the ice sheets and accurate mapping of the bedrock below.
«The ice shelf generally breaks at points that are between a half and full
thickness of the ice sheet from the edge,» summarises Christmann.
At the Dome A site in East Antarctica — roughly the size of the state of California — the base layer of refrozen ice accounted for up to half the total
thickness of the ice sheet, and 24 percent of the area covered by ice.
Radar images show that water under the base of the ice sheet refreezes into ice, creating a new bottom layer that accounts for up to half the total
thickness of the ice sheet in some locations.
From an altitude of just over 700 km, CryoSat will precisely monitor changes in the thickness of sea ice and variations in
the thickness of the ice sheets on land.
Not exact matches
the south - bound expedition had cleared that vast plain
of floating
ice which flows down from the great mountains
of the interior and covers the southern part
of Ross Sea throughout an area above 20,000 square miles with an
ice sheet approximately 800 feet in
thickness, and had begun to climb the heights which form the mountainous embayment at the head
of Ross Sea.
Although CryoSat - 2 is designed to measure changes in the
ice sheet elevation, these can be translated into horizontal motion at the grounding line using knowledge
of the glacier and sea floor geometry and the Archimedes principle
of buoyancy — which relates the
thickness of floating
ice to the height
of its surface.
Ambient geothermal heat emanating up from the seafloor melts the underside
of the
ice sheet at a rate
of several penny
thicknesses per year.
With a volume
of more than 700,000 cubic miles and an average
thickness of 4,000 feet, the West Antarctic
Ice Sheet (WAIS) holds enough water to raise sea levels by 15 to 20 feet — and it is already sweating off 130 billion tons of ice per ye
Ice Sheet (WAIS) holds enough water to raise sea levels by 15 to 20 feet — and it is already sweating off 130 billion tons
of ice per ye
ice per year.
The lakes are fed by geothermal heat that seeps up from the Earth's interior, melting away the bottom
of the
ice sheet at a rate
of several dime -
thicknesses per year and liberating water from the
ice.
Previous observations
of the
thickness of Antarctic sea
ice produced a mean draught — the depth between the waterline and the bottom
of the
ice sheet —
of around 1 meter; the new work gives a mean draught
of over 3 meters.
Many older models
of Greenland assumed that its massive
ice sheet sat on bedrock that was relatively flat, even though scientists did not know the full
thickness of the
ice.
If everything goes according to plan, the radar will be turned on and will start to collect data on the
thickness of glaciers and
ice sheets just three days post-launch.
In some parts
of Antarctica,
ice sheets have been losing 30 feet a year in
thickness since 2003, according to the study....
NASA and the USGS have used MRO instruments to analyze the vertical structure and
thickness of buried
ice sheets, which preserve a detailed record
of the Red Planet's past and could provide future human explorers with an easily - accessible water supply.
Inferring Histories
of Accumulation,
Ice Flow, and
Ice Thickness from Internal Layers in
Ice Sheets.
The
ice sheet's
thickness makes its temperature much more resistant to change than the six inches
of snow that might fall on your driveway during a winter snowstorm.
So unless the perimeter
of the Greenland
ice sheet is the exact same
thickness as the entire
ice sheet (say 3 km on average), an area loss there,
of 15 %, will produce a much smaller % volume loss, than say if this area loss were smack dab in the middle
of the Greenland
ice sheet.
[Response: The
thickness of the greenland
ice sheet is ~ 2000 m on average (don't quote me, that's a ballpark estimate).
why not a sawtooth, characteristic
of a relaxation oscillator, where something (voltage on a capacitor,
ice sheet thickness) accumulates until it reaches a tipping point (neon lamp trigger voltage, basal warming), then suddenly the state changes?
... the confusion came most likely from a confusion in definitions
of what is the permanent
ice sheet, and what are glaciers, with the «glaciers» being either dropped from the Atlas entirely or colored brown (instead
of white)... there is simply no measure — neither
thickness nor areal extent — by which Greenland can be said to have lost 15 %
of its
ice.
It is a thin layer
of 2 - 3 meters
thickness — unlike the 3,000 meter thick Greenland
Ice Sheet.
Ice shelf - A floating slab of ice of considerable thickness extending from the coast (usually of great horizontal extent with a level or gently sloping surface), often filling embayments in the coastline of the ice shee
Ice shelf - A floating slab
of ice of considerable thickness extending from the coast (usually of great horizontal extent with a level or gently sloping surface), often filling embayments in the coastline of the ice shee
ice of considerable
thickness extending from the coast (usually
of great horizontal extent with a level or gently sloping surface), often filling embayments in the coastline
of the
ice shee
ice sheets.
(Right) Extents and
thicknesses of the Greenland
Ice Sheet and western Canadian and Iceland glaciers at their minimum extent during the last interglacial, shown as a multi-model average from three ice mode
Ice Sheet and western Canadian and Iceland glaciers at their minimum extent during the last interglacial, shown as a multi-model average from three
ice mode
ice models.
The
ice sheet's
thickness makes its temperature much more resistant to change than the six inches
of snow that might fall on your driveway during a winter snowstorm.
Although CryoSat - 2 is designed to measure changes in the
ice sheet elevation, these can be translated into horizontal motion at the grounding line using knowledge
of the glacier and sea floor geometry and the Archimedes principle
of buoyancy — which relates the
thickness of floating
ice to the height
of its surface.
These hydrates are likely in a sensitive equilibrium that could be disrupted by small changes in pressure, caused by variations in the
thickness of the overlying
ice sheets.
Researchers used data from IceBridge's
ice - penetrating radar — the Multichannel Coherent Radar Depth Sounder, or MCoRDS, which is operated by the Center for Remote Sensing of Ice Sheets at the University of Kansas, Lawrence, Kan. — to determine ice thickness and sub-glacial terrain, and images from satellite sources such as Landsat and Terra to calculate veloci
ice - penetrating radar — the Multichannel Coherent Radar Depth Sounder, or MCoRDS, which is operated by the Center for Remote Sensing
of Ice Sheets at the University of Kansas, Lawrence, Kan. — to determine ice thickness and sub-glacial terrain, and images from satellite sources such as Landsat and Terra to calculate veloci
Ice Sheets at the University
of Kansas, Lawrence, Kan. — to determine
ice thickness and sub-glacial terrain, and images from satellite sources such as Landsat and Terra to calculate veloci
ice thickness and sub-glacial terrain, and images from satellite sources such as Landsat and Terra to calculate velocity.
Recent research indicates it may be related to increasing friction at the base
of the
ice sheets slowing ablation and allowing greater
thicknesses.
You are certainly right about the
thickness of the Antarctic snow, and the point goes double for the
ice sheet — that's why fluctuations in the AIS can cause tens
of meters
of sea level rise.
5.3.7 In the Polar Regions, the main effect foreseen is a reduction in
thickness and extent
of glaciers,
ice sheets, sea
ice, and permafrost, and associated impacts on infrastructures, ecosystems, and traditional ways
of life.
This thin
ice cap is very different from the Greenland Ice Sheet where the enormous thickness gives it a very slow response time and the type of process you are suggesting can opera
ice cap is very different from the Greenland
Ice Sheet where the enormous thickness gives it a very slow response time and the type of process you are suggesting can opera
Ice Sheet where the enormous
thickness gives it a very slow response time and the type
of process you are suggesting can operate.
If hydrates are present beneath the Antarctic
ice sheet, they could be destabilized by reducing the pressure, as a result
of the reduction
of the
ice thickness.
On time scales
of years to centuries, the largest changes in tides around the
ice sheets are likely to be caused by changes in the extent and
thickness of ice shelves.
That is the discovery made by scientists using data from CryoSat - 2, the European probe that has been measuring the
thickness of Earth's
ice sheets and glaciers since it was launched by [continue reading...]
With a step change in temperature at the surface
of the
ice sheet, and assuming a constant
thickness of 2 km, the time required for the mid-point
of the
ice sheet to reflect only 50 % absorption
of the energy reflecting the temperature increase is... 159.5 years.
http://www.livescience.com/24168-glacier-volume-sea-level-rise.html «Researchers calculated the
ice thickness for 171,000 glaciers worldwide, excluding the Greenland and Antarctic
ice sheets, which hold the bulk
of Earth's frozen water.
Researchers calculated the
ice thickness for 171,000 glaciers worldwide, excluding the Greenland and Antarctic
ice sheets, which hold the bulk
of Earth's frozen water.
Further, there has been an almost worldwide reduction in glacial mass and extent in the 20th century; melting
of the Greenland
Ice Sheet has recently become apparent; snow cover has decreased in many Northern Hemisphere regions; sea ice thickness and extent have decreased in the Arctic in all seasons, most dramatically in spring and summer; the oceans are warming; and sea level is rising due to thermal expansion of the oceans and melting of land
Ice Sheet has recently become apparent; snow cover has decreased in many Northern Hemisphere regions; sea
ice thickness and extent have decreased in the Arctic in all seasons, most dramatically in spring and summer; the oceans are warming; and sea level is rising due to thermal expansion of the oceans and melting of land
ice thickness and extent have decreased in the Arctic in all seasons, most dramatically in spring and summer; the oceans are warming; and sea level is rising due to thermal expansion
of the oceans and melting
of land
iceice