EnviSat was a satellite mission monitoring Earth's environment. EnviSat application areas included meteorology, climatology, environment, atmospheric chemistry, vegetation, hydrology, land use, and ocean and ice processes. EnviSat was a research mission that carried ten instruments and provided a wealth of data related to Earth's health and climate change. EnviSat carried the Medium Resolution Imaging Spectrometer( MERIS), Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), Radar Altimeter-2 (RA-2), Laser Retro-Reflector (LRR), Microwave Radiometer (MWR), Advanced SAR (ASAR), Global Ozone Monitoring by Occultation of Stars (GOMOS), Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), Advanced Along Track Scanning Radiometer, provided by the UK and Australia (AATSR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS).

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]

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.

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

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.

ICESat (Ice, Cloud, and Land Elevation Satellite) is a NASA/GSFC mission within the ESE (Earth Science Enterprise) program. The prime objective is to monitor the mass balance of the polar ice sheets and their contributions to global sea level change. Secondary goals are to measure cloud heights and the vertical structure of clouds and aerosols in the atmosphere, further to measure roughness, reflectivity, vegetation heights, snow-cover, and sea-ice surface characteristics, and to map topography of land surfaces. Note: ICESat is the renamed former "Laser Altimetry-1" mission.

Pertaining to the extent, depth, and longevity of snow pack.

Polar stratospheric clouds (PSCs) play a central role in the formation of the ozone hole in the Antarctic and Arctic. PSCs provide surfaces upon which heterogeneous chemical reactions take place. These reactions lead to the production of free radicals of chlorine in the stratosphere which directly destroy ozone molecules. PSCs form poleward of about 60°S latitude in the altitude range 10 km to 25 km during the winter and early spring. The clouds are classified into Types I and II according to their particle size and formation temperature. Type II clouds, also known as nacreous or mother-of-pearl clouds, are composed of ice crystals and form when temperatures are below the ice frost point (typically below -83°C). The Type I PSCs are optically much thinner than the Type II clouds, and have a formation threshold temperature 5 to 8°C above the frost point. These clouds consist mainly of hydrated droplets of nitric acid and sulphuric acid. Despite two decades of research, the climatology of PSCs is not well described, and this impacts on the accuracy of ozone depletion models. The timing and duration of PSC events, their geographic extent and vertical distributions, and their annual variability are not well understood.The Davis lidar has been used to study stratospheric clouds since 2001. The observations consist of profiles of Rayeligh laser backscatter at a wavelength of 532 nm as a function of altitude. The measurements are being used to investigate the climatology of the clouds and their relation to the temperature structure of the stratosphere, and the influence of atmospheric gravity waves and planetary waves in modulating their structure and ozone depletion.

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