Launched in October 2005, CryoSat was a next-generation radar altimetry mission, aiming to determine variations in the thickness of the Earth's continental ice sheets and marine ice cover. Primary objective is to test the prediction of thinning arctic ice due to global warming. CryoSat was supposed to be the first Earth Explorer Opportunity mission in ESA's Living Planet program, but was lost in a launch failure on 8 October 2005, prompting the development of a successor mission, CryoSat-2.

Difference of sea surface height and mean sea surface. Sea surface height may be corrected using models for effects such as tides and atmospheric forcing

The Arctic Oscillation (AO) is the dominant pattern of non-seasonal sea-level pressure (SLP) variations north of 20N, and it is characterized by SLP anomalies of one sign in the Arctic and anomalies of opposite sign centered about 37-45N. Additional information is available for the Arctic Oscillation (AO) and for the North Atlantic Oscillation (NAO), a close relative of the AO (http://jisao.washington.edu/ao/)

The ERS-1 (European Remote Sensing Satellite -1) was the first environmental monitoring satellite developed by ESA. The mission detected land and ocean surface change and provided observation data on oceans, polar ice, vegetation, geology, meteorology and ecology.

The Antarctic Oscillation (AAO) is the dominant pattern of non-seasonal tropospheric circulation variations south of 20S, and it is characterized by pressure anomalies of one sign centered in the Antarctic and anomalies of the opposite sign centered about 40-50S. The AAO is also referred to as the Southern Annular Mode (SAM). There is a Northern Hemisphere analog to the AAO, and it is called the Arctic Oscillation (or Northern Annular Mode).

Habitat found in the zone on mountain tops between permanent snow and the cold limits of trees, or in arctic regions, characterized by very low winter temperatures, short cool summers, permafrost below a surface layer subject to summer melt, short growing season, and low precipitation.[The Nature Conservancy]

The measurement and charting of the spatial variation of the ocean depths.

There are no Arctic-wide or Antarctic-wide measurements of the volume of sea ice, but the volume of the Arctic sea ice is calculated using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed at the University of Washington Applied Physics Laboratory/Polar Science Center. PIOMAS blends satellite-observed sea ice concentrations into model calculations to estimate sea ice thickness and volume. Comparison with submarine, mooring, and satellite observations help increase the confidence of the model results

This dataset presents biweekly gridded sea ice thickness and uncertainty for the Arctic derived from the European Space Agency's satellite CryoSat-2. An associated 'developer's product' also includes intermediate parameters used or output in the sea ice thickness processing chain. Data are provided as biweekly grids with a resolution of 80 km, mapped onto a Northern Polar Stereographic Grid, covering the Arctic region north of 50 degrees latitude, for all months of the year between October 2010 and July 2020. CryoSat-2 Level 1b Baseline-D observed radar waveforms have been retracked using two different approaches, one for the 'cold season' months of October-April and the second for 'melting season' months of May-September. The cold season retracking algorithm uses a numerical model for the SAR altimeter backscattered echo from snow-covered sea ice presented in Landy et al. (2019), which offers a physical treatment of the effect of ice surface roughness on retracked ice and ocean elevations. The method for optimizing echo model fits to observed CryoSat-2 waveforms, retracking waveforms, classifying returns, and deriving sea ice radar freeboard are detailed in Landy et al. (2020). The melting season retracking algorithm uses the SAMOSA+ analytical echo model with optimization to observed CryoSat-2 waveforms through the SARvatore (SAR Versatile Altimetric Toolkit for Ocean Research and Exploitation) service available through ESA Grid Processing on Demand (GPOD). The method for classifying radar returns and deriving sea ice radar freeboard in the melting season are detailed in Dawson et al. (2022). The melting season sea ice radar freeboards require a correction for an electromagnetic range bias, as described in Landy et al. (2022). After applying the correction, year-round freeboards are converted to sea ice thickness using auxiliary satellite observations of the sea ice concentration and type, as well as snow depth and density estimates from a Lagrangian snow evolution scheme: SnowModel-LG (Stroeve et al., 2020; Liston et al., 2020). The sea ice thickness uncertainties have been estimated based on methods described in Landy et al. (2022). NetCDF files contain detailed descriptions of each parameter. Funding was provided by the NERC PRE-MELT grant NE/T000546/1 and the ESA Living Planet Fellowship Arctic-SummIT grant ESA/4000125582/18/I-NS.

Sentinel-2 is a constellation of two optical imaging satellites, which are a part of Copernicus - the European Union's Earth observation program.