See Partington et al. (2003) for an assessment of operational versus satellite -
derived ice concentration.
Pond formation and small floe sizes in dispersed ice (and coastal effects on the radiometer signal) contribute to substantial biases in
the derived ice concentration data.
It should be noted that this number represents a monthly average and is dependent on a particular passive microwave algorithm to
derive ice concentration (see the CliC Arctic Sea Ice Working Group note on the accuracy of satellite - derived passive microwave estimates of sea ice extent).
Not exact matches
Variations of deuterium (δD; black), a proxy for local temperature, and the atmospheric
concentrations of the greenhouse gases CO2 (red), CH4 (blue), and nitrous oxide (N2O; green)
derived from air trapped within
ice cores from Antarctica and from recent atmospheric measurements (Petit et al., 1999; Indermühle et al., 2000; EPICA community members, 2004; Spahni et al., 2005; Siegenthaler et al., 2005a, b).
This was a relatively stable climate (for several thousand years, 20,000 years ago), and a period where we have reasonable estimates of the radiative forcing (albedo changes from
ice sheets and vegetation changes, greenhouse gas
concentrations (
derived from
ice cores) and an increase in the atmospheric dust load) and temperature changes.
«the European Project for
Ice Coring in Antarctica (EPICA) established a precise link between climate records from Greenland and Antarctica using data on global changes in methane concentrations derived from trapped air bubbles in the ice.&raq
Ice Coring in Antarctica (EPICA) established a precise link between climate records from Greenland and Antarctica using data on global changes in methane
concentrations derived from trapped air bubbles in the
ice.&raq
ice.»
Another simulation incorporated prescribed sea
ice loss in autumn and winter based on satellite -
derived Arctic sea
ice concentrations.
This estimate was refined by Hansen and Nazarenko (2004), who used measured BC
concentrations within snow and
ice at a wide range of geographic locations to deduce the perturbation to the surface and planetary albedo,
deriving an RF of +0.15 W mâ $ «2.
Data is from the National Snow and
Ice Data Center, monthly sea ice concentration derived from the passive microwave record (NASA Team algorith
Ice Data Center, monthly sea
ice concentration derived from the passive microwave record (NASA Team algorith
ice concentration derived from the passive microwave record (NASA Team algorithm).
Method: Daily updated statistical regression based on sea
ice concentration derived from 85 GHz SSM / I data.
The primary sources of the post-1972 data are the hemispheric fields of sea -
ice concentration from (1) the U.S. National Ice Center (NIC), whose weekly grids (derived primarily from satellite data) span the period 1972 - 1994, and (2) the satellite passive - microwave grids from the Scanning Multichannel Microwave Radiometer (SMMR) / Special Sensor Microwave / Imager (SSM / I) period, 1978 - 97 (Parkinson and others, 199
ice concentration from (1) the U.S. National
Ice Center (NIC), whose weekly grids (derived primarily from satellite data) span the period 1972 - 1994, and (2) the satellite passive - microwave grids from the Scanning Multichannel Microwave Radiometer (SMMR) / Special Sensor Microwave / Imager (SSM / I) period, 1978 - 97 (Parkinson and others, 199
Ice Center (NIC), whose weekly grids (
derived primarily from satellite data) span the period 1972 - 1994, and (2) the satellite passive - microwave grids from the Scanning Multichannel Microwave Radiometer (SMMR) / Special Sensor Microwave / Imager (SSM / I) period, 1978 - 97 (Parkinson and others, 1999).
Trends in the satellite -
derived Arctic sea
ice concentrations (1978 - 2002) show pronounced decreases in the Barents / Kara Seas, between the Chukchi and Beaufort Seas, the central Sea of Okhotsk and a portion of the Hudson / Baffin Bay by ∼ 2 - 8 % per decade, exceeding the 95 % confidence level.
Raw model sea
ice concentration data was processed using a simple linear regression model and satellite
derived ice extent to produce bias corrected predictions.
Finally, passive microwave brightness temperatures from various satellite platforms have been extensively used to
derive estimates of sea
ice concentration.
Although several different algorithms have been used to
derive sea
ice concentrations from the satellite measurements, our analyses based on the Hurrell et al. (2008) data are consistent with previous studies.
The last image is the US National Snow and
Ice Data Center's satellite - derived sea ice concentration image for August 20
Ice Data Center's satellite -
derived sea
ice concentration image for August 20
ice concentration image for August 2012.
I have repeatedly pointed out (in several places including WUWT) that (1)
ice core data are useful because they indicate CO2
concentration and isotope -
derived temperature data from the same trapped gas bubbles but (2)
ice core data are NOT a direct indication of anything because (2a) different
ice cores provide different indications and (2b) other proxies (e.g. stomata data) provide different indications to those of the
ice cores and to each other.
CO2
Concentrations: record of global CO2
concentration for the last 1000 years,
derived from measurements of CO2
concentration in air bubbles in the layered
ice cores drilled in Antarctica (blue line) and from atmospheric measurements since 1957.