Sentinel-1 is a constellation of two imaging radar satellites operated by ESA. Sentinel-1B experienced an anomaly which rendered it unable to deliver radar data in December 2021, and the launch of Sentinel-1C is planned for 2023.

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

Albedo is the ratio of the radiation (radiant energy or luminous energy) reflected by a surface to that incident on it. Snow and cloud surfaces have a high albedo, because most of the energy of the visible solar spectrum is reflected. Vegetation and ocean surfaces have low albedo, because they absorb a large fraction of the energy. Clouds are the chief cause of variations in the Earth's albedo.The land surface albedo is the ratio of the radiant flux reflected from Earth's surface to the incident flux. It is a key forcing parameter controlling the partitioning of radiative energy between the atmospheric and surface. In the case of vegetation, a reference surface is typically defined at or near the top of the canopy and must be specified explicitly. Surface albedo depends on natural variations, highly variable in space and time as a result of terrestrial properties changes, and with illumination conditions and human activities and is a sensitive indicator of environmental vulnerability.

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

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.

ClONO2 - This is a stratospheric reservoir species for chlorine and nitrogen, two of the catalysts in the breakdown of ozone. It reacts with HCl at low temperatures on the surfaces of polar stratospheric clouds (PSCs over Antarctica and possibly in the stratosphere over the Arctic). That normally slow reaction heterogeneously produces molecular chlorine and nitric acid. The former outgases from the PSC surface and is quickly photolyzed by 450 nm or shorter wavelength light to form chlorine radicals which rapidly catalyze the breakdown of ozone (see chlorine monoxide). [Science; v 238; pages 1258-1260; 1987.] [Science; v 258; pages 1342-1345; 1992.]

Pertaining to the measured height of large thick, glaciers, with an area of at least 50,000 sq. km, covering a continuous stretch of land and growing in all directions.

ERS-2 (European Remote Sensing Satellite -2) was launched in April 1995, the ERS-2 was an enhancement of the previous ERS-1 mission. ERS-2 provided microwave spectrum environmental monitoring across a range of disciplines (oceans, polar ice, forestry).

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.

GRACE (Gravity Recovery And Climate Experiment) satellites mapped detailed measurements of the global gravitational fields with unprecedented precision. Data from GRACE satellites covered wide application areas. GRACE consists of two satellites (A, B) serving one mission.