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Theme 5 (Cryosphere and Polar Oceans) Sea Ice Elevation and Thickness and Ice Sheet Elevation Change: ENVISAT Radar Altimeter 2 (RA-2) 5-year Time Series (2002-2008) of Ice Thickness data

Update Frequency: Not Planned
Status: Completed
Online Status: ONLINE
Publication State: Published
Publication Date: 2011-09-04
Download Stats: last 12 months


Theme 5 - Cryosphere and Polar Oceans - of the National Centre for Earth Observation (NCEO) is aimed at resolving uncertainties in future climate and sea-level arising from behaviour of the cryosphere. Under this theme, 5 year time series Ice thickness data used by Katharine Giles, Seymour Laxon and Andy Ridout in their paper "Circumpolar thinning of Arctic sea ice following the 2007 record ice extent minimum" (Geophysical Research Letters, Vol. 35, L22502, doi:10.1029/2008GL035710, 2008) are presented.

Citable as:  National Centre for Earth Observation; Giles, K.A.; Laxon, S.W.; Ridout, A. (2011): Theme 5 (Cryosphere and Polar Oceans) Sea Ice Elevation and Thickness and Ice Sheet Elevation Change: ENVISAT Radar Altimeter 2 (RA-2) 5-year Time Series (2002-2008) of Ice Thickness data. NERC Earth Observation Data Centre, date of citation.
Abbreviation: NCEO_T5_Ice_thickness
Keywords: ice, nceo, polar


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Data lineage:

Data prepared by authors and sent to the NERC Earth Observation Data Centre (NEODC) where data were re-formatted to use the BADC-CSV (British Atmospheric Data Centre) file format prior to archiving at the NEODC.

File Format:
BADC-CSV formatted file

Process overview

This dataset was generated by a combination of instruments deployed on platforms and computations as detailed below.

Computation Element: 1

Title Theme 5 (Cryosphere and Polar Oceans) Sea Ice Elevation and Thickness and Ice Sheet Elevation Change
Abstract To generate winter averages for each season, the data were seasonally adjusted to the 1st January using an average winter growth curve derived from the data. The seasonally adjusted data were averaged onto 100 × 100 km grid cells on a polar stereographic projection. We estimated the errors in ice thickness for each grid cell as follows: The error in the ice freeboard was calculated using equation (1) from Giles and Hvidegaard [2006], with an additional term to account for the error in the velocity of the radar signal through the snow pack. The error in the estimate of ice thickness in each grid cell was then calculated from equation (3) of Giles et al. [2007], with errors in the ice and water densities taken to be 5 kg m−3 and 0.5 kg m−3 respectively [Wadhams et al., 1992], the snow density error taken to be 3 kg m−3 [Warren et al., 1999], and snow depth error taken to be the interannual variability (IAV) in snow depth of 0.03 m from Radionov et al. [1996]. For each winter season we then calculated ice thickness anomalies for each grid cell, which contained data for all years, by removing the six-year mean thickness for that cell. The error in the anomaly for each grid cell was also computed. Our grids of ice thickness anomalies were then averaged over the Arctic for each winter season, inversely weighted by the error on each grid cell, to generate regional or circumpolar averages.
Input Description None
Output Description None
Software Reference None
Output Description None
  • long_name: AO anomaly
  • names: AO anomaly
  • long_name: Arctic Ocean err
  • names: Arctic Ocean err
  • long_name: EA anomaly +65 lat
  • names: EA anomaly +65 lat
  • long_name: EA err
  • names: EA err
  • long_name: WA anomaly +65 lat
  • names: WA anomaly +65 lat
  • long_name: WA err
  • names: WA err
  • long_name: normalised date
  • names: normalised date
  • long_name: start of season
  • names: start of season

Co-ordinate Variables

Temporal Range
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Geographic Extent