Using Envisat radar altimeter data, scientists from the Centre for Polar Observation and Modelling at University College London (UCL) measured
sea ice thickness over the Arctic from 2002 to 2008 and found that it had been fairly constant until the record loss of ice in the summer of 2007.
At Twitter Kirye posted an excellent GIF animation to compare Arctic
sea ice thickness over the past 10 years:
Not exact matches
Together with his AWI colleague Dr Stefan Hendricks, they evaluated the
sea ice thickness measurements taken
over the past five winters by the CyroSat - 2 satellite for their
sea ice projection.
«It may even be possible to predict
sea ice cover a year in advance with high - quality observations of
sea ice thickness and snow cover
over the whole Arctic,» said Cecilia Bitz, co-author and professor of atmospheric sciences at the University of Washington.
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.
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.
We find a consistent decreasing trend in Arctic Ocean
sea ice thickness since 1979, and a steady decline in the Eastern Arctic Ocean
over the full 40 - year period of comparison that accelerated after 1980, but the predictions of Western Arctic Ocean
sea ice thickness between 1962 and 1980 differ substantially.
Although the Arctic Ocean is typically mostly covered by
ice, both the
thickness and extent of summer
sea ice in the Arctic have shown a dramatic decline
over the past thirty years, satellite measurements have found.
The
thickness of Arctic
sea ice has also been on a steady decline
over the last several decades.
Over the
sea ice field the observations include:
sea ice freeboard height and hence
sea ice thickness from radar altimetry;
sea ice surface temperature and
sea ice drift from respectively infrared radiometer and imaging spectrometer under cloud free conditions.
Peter Wadhams, President of the International Association on
Sea Ice and Head of the Polar Ocean Physics Group / Department of Applied Mathematics and Theoretical Physics, University of Cambridge, says: «It is quite urgent that we recognize what is going on... the ice has been getting thinner over the last 40 years since I have been measuring it, and it has lost about one - half of its thickness... five years ago the shrinkage started to accelera
Ice and Head of the Polar Ocean Physics Group / Department of Applied Mathematics and Theoretical Physics, University of Cambridge, says: «It is quite urgent that we recognize what is going on... the
ice has been getting thinner over the last 40 years since I have been measuring it, and it has lost about one - half of its thickness... five years ago the shrinkage started to accelera
ice has been getting thinner
over the last 40 years since I have been measuring it, and it has lost about one - half of its
thickness... five years ago the shrinkage started to accelerate.
Aerial
thickness surveys and ground - based sampling in the western Beaufort and eastern Chukchi
Sea in April this year indicate that level
ice in the region is well
over 3 m thick and strong (due to low salt content; www.sizonet.org).
On page 16 here: https://curryja.files.wordpress.com/2014/10/
sea-
ice-physical-processes.pdf There is the «Annual cycle of net surface heat flux for various
ice thicknesses» Roughly interpolating the no
sea ice flux I got an average of — 310 Wm2
over the course of a year.
Therefore, due to entirely natural variations in spring snow conditions
over sea ice (and
thickness of the
ice), 2 polar bear population sizes can vary by region.
Poitou & Bréon do not explain why the
ice pack volume would be relevant for the albedo; according to Haas (2005)[47] the changes of the
thickness of the
sea ice are small since they are correctly measured by an airborne radio apparatus, only
over the Arctic.
In response to your question I would refer you to my comment above Dave Wendt (14:39:39): where I discuss the Rigor and Wallace paper of 2004 which demonstrated that the decline in
sea ice age and
thickness began with a shift in state in Beaufort Gyre and the TransPolar Drift in 1989 which resulted in multiyear
ice declining from
over 80 % of the Arctic to 30 % in about one year and that the persistence of that pattern has been responsible for the continuing decline.
April 1, 2009
Sea ice cover
over the Arctic Ocean typically reaches its maximum geographic extent and
thickness just as spring begins in the Northern Hemisphere.
According to scientific measurements, both the
thickness and extent of summer
sea ice in the Arctic have shown a dramatic decline
over the past thirty years.
In addition, records from Russian coastal stations show the extent and
thickness of
sea ice has varied greatly
over 60 - to 80 - year periods during the last 125 years.
Based on the understanding of both the physical processes that control key climate feedbacks (see Section 8.6.3), and also the origin of inter-model differences in the simulation of feedbacks (see Section 8.6.2), the following climate characteristics appear to be particularly important: (i) for the water vapour and lapse rate feedbacks, the response of upper - tropospheric RH and lapse rate to interannual or decadal changes in climate; (ii) for cloud feedbacks, the response of boundary - layer clouds and anvil clouds to a change in surface or atmospheric conditions and the change in cloud radiative properties associated with a change in extratropical synoptic weather systems; (iii) for snow albedo feedbacks, the relationship between surface air temperature and snow melt
over northern land areas during spring and (iv) for
sea ice feedbacks, the simulation of
sea ice thickness.
NASA satellites have seen the minimum summertime
sea ice coverage decline by 13 percent
over the last three decades, along with a decline in
sea ice thickness.
The Arctic coastal regions of the Chukchi and Beaufort
Seas generally are covered with shore - fast
ice for about eight months, but
over the past two decades,
sea ice extent and
thickness have diminished.
Recall the long - term military submarine record of decreasing seasonal Arctic
sea ice thickness that was kept secret for
over a decade?
The research, reported in Geophysical Research Letters, showed that last winter the average
thickness of
sea ice over the whole Arctic fell by 26 cm (10 %) compared with the average
thickness of the previous five winters, but
sea ice in the western Arctic lost around 49 cm of
thickness.
And scientists from NASA recently flew a series of missions
over the Arctic during the IceBridge project, to study details of Arctic
sea ice thickness as well as changing glaciers in Greenland.
Last winter the average
thickness of
sea ice over the whole Arctic fell by 26 cm (10 %) compared with the average
thickness of the previous five winters, but
sea ice in the western Arctic lost around 49 cm of
thickness.