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

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.

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 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/)

Launched in June 2008, Jason-2, also referred to as the Ocean Surface Topography Mission (OSTM), was the follow-on mission from Jason-1 and Posiedon/TOPEX. In this mission, the National Aeronautics and Space Administration (NASA) and Centre National d'Etudes Spatiales (CNES) worked collaboratively with the National Oceanic and Atmospheric Administration (NOAA) and European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) to extend the existing time series of ocean surface topography measurements. Jason-2 successfully obtained a continuous record of observations in line with previous missions which included measurements of time-averaged ocean circulation, global sea-level change and improved open ocean tide models, until it was decommissioned in October 2019.

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

Soil Moisture and Ocean Salinity (SMOS) mission is a microwave imaging satellite whose operation is led by ESA as part of their Earth Explorer missions. SMOS provides global observations on soil moisture and ocean salinity to improve our understanding of the water cycle and our weather forecasting ability.

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]

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.

Discharge is the volume rate of water flow, including any suspended solids (i.e. sediment), dissolved chemical species (i.e. CaCO3(aq)) and/or biologic material (i.e. diatoms), which is transported through a given cross-sectional area.[Buchanan, T.J. and Somers, W.P., 1969, Discharge Measurements at Gaging Stations: U.S. Geological Survey Techniques of Water-Resources Investigations, Book 3, Chapter A8, 1p. Wikipedia: http://en.wikipedia.org/wiki/Discharge_%28hydrology%29#cite_note-0]