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What is an ECV?

Over the last decade, the Global Climate Observing System (GCOS), in support of the UNFCCC, have put together a set of requirements for satellite data to meet the needs of the climate change community. These are broken down into key parameters of the Earth system, or 'Essential Climate Variables' (ECVs) as they are known. The specifications given by GCOS for each ECV data product are designed to provide information to characterise the state of the global climate system and enable long-term climate monitoring. 

In 2010 50 ECVs were defined by GCOS, with are required to support the work of the UNFCCC and the IPCC. These are described in the table below. All ECVs are technically and economically feasible for systematic observation. It is these variables for which international exchange is required for both current and historical observations.
 

Domain GCOS Essential Climate Variables
 

Atmospheric

(over land, sea and ice)

Surface: Air temperature, Wind speed and direction, Water vapour, Pressure, Precipitation, Surface radiation budget
Upper-Air: Temperature, Wind speed and direction, Water vapour, Cloud properties, Earth radiation budget (including solar irradiance)
Composition: Carbon dioxide, Methane, and other long-lived greenhouse gases, Ozone and Aerosol, supported by their precursors
Oceanic Surface: Sea-surface temperature, Sea-surface salinity, Sea level, Sea state, Sea ice, Surface current, Ocean colour, Carbon dioxide partial pressure, Ocean acidity, Phytoplankton
Sub-Surface: Temperature, Salinity, Current, Nutrients, Carbon dioxide partial pressure, Ocean acidity, Oxygen, Tracers
Terrestrial River discharge, Water use, Groundwater, Lakes, Snow cover, Glaciers and ice caps, Ice sheets, Permafrost, Albedo, Land cover (including vegetation type), Fraction of absorbed photosynthetically active radiation (FAPAR), Leaf area index (LAI), Above-ground biomass, Soil carbon, Fire disturbance, Soil moisture.