THE CEOS DATABASE : Missions, Instruments and Measurements
GLOBAL CLIMATE OBSERVING SYSTEM
ESSENTIAL CLIMATE VARIABLES INDEX

This page lists the Global Climate Observing System (GCOS) Essential Climate Variables (ECVs). The contents of this index are derived from the 2015 Status of the Global Observing System for Climate (GCOS-195), and the CEOS Response to the GCOS IP (2015 Update). The ECVs are listed alphabetically by domain. Click the links to view ECV details.

indicates ECVs for which GCOS has determined satellite observations make a significant contribution.

atmospheric · oceanic · terrestrial
Atmospheric ECVs

Atmospheric

14 of 17 ECVs have a significant contribution from satellite EO

Atmospheric - Surface

ECVGlobal Products requiring Satellite ObservationsFundamental Climate Data Records required for Product Generation (from past, current, and future missions)Product Numbers (IP-10 Reference Actions)
Air temperature

Surface air temperature has profound and widespread impacts on human lives and activities, affecting health, agriculture, energy demand and much more. click for more
N/AN/AN/A
Precipitation

Precipitation, either liquid or solid, is perhaps the single most important climate variable directly affecting mankind. click for more
Estimates of liquid and solid precipitation, derived from specific instruments and provided by composite productsPassive microwave radiances
Geostationary VIS/NIR/IR radiances
A.2: Estimates of liquid and solid precipitation, derived from specific instruments and provided by composite products
Pressure

Surface pressure is a fundamental meteorological variable for which observations are required for initialising forecasts and for use in reanalysis systems. click for more
N/AN/AN/A
Surface radiation budget

Radiation at the Earth’s surface is a fundamental component of the surface energy budget that is crucial to many aspects of the working of the climate system, including its energy and hydrological cycles. click for more
N/AN/AN/A
Water vapour

The humidity of air near the surface of the Earth affects the comfort and health of humans, livestock and wildlife, the swarming behaviour of insects and the occurrence of plant disease. click for more
Passive microwave radiances
UV/VIS imager radiances
IR and microwave radiances
Limb soundings
Passive microwave radiances
UV/VIS imager radiances
IR and microwave radiances
Limb soundings
A.5.1: Total column water vapour
A.5.2: Tropospheric and lower-stratospheric profiles of water vapour
A.5.3: Upper tropospheric humidity
Wind speed and direction

Surface wind has substantial influence on the exchanges of momentum, heat, moisture and trace species between the atmosphere and the underlying ocean and land. click for more
Surface wind retrievalsPassive microwave radiances and radar backscatterA.1: Surface Wind Retrievals
atmospheric · oceanic · terrestrial · top

Atmospheric - Upper-air

ECVGlobal Products requiring Satellite ObservationsFundamental Climate Data Records required for Product Generation (from past, current, and future missions)Product Numbers (IP-10 Reference Actions)
Cloud Properties

The variable properties of clouds determine their profound effects on radiation and precipitation. click for more
Cloud amount, top pressure and temperature, optical depth, water path and effective particle radiusVIS/IR imager radiances
IR and microwave radiances
Lidar
A.6.1: Cloud amount (CA)
A.6.2: Cloud top pressure (CTP)
A.6.3: Cloud top temperature (CTT)
A.6.4: Cloud optical depth (COD)
A.6.5: Cloud water path (liquid and ice) (CWP)
A.6.6: Cloud effective particle radius (liquid and ice) (CRE)
Earth radiation budget

The primary observations related to the Earth’s radiation budget are of solar irradiance, the external driver of the climate system, and of the almost compensating reflected solar and emitted longwave radiation that leaves the atmosphere. click for more
Earth radiation budget (top-of- atmosphere and surface)
Total and spectrally-resolved solar irradiance
Broadband radiances
Spectrally-resolved solar irradiances
Geostationary multispectral imager radiances
A.7.1: Earth radiation budget (top-of-atmosphere and surface)
A.7.2: Total and spectrally resolved solar irradiance
Temperature

Temperature is one of the fundamental state variables for which observation is essential for understanding and predicting the behaviour of the atmosphere. click for more
Upper-air temperature retrievals Temperature of deep atmospheric layersPassive microwave and IR radiances
GNSS radio occultation bending angles
A.3.1: Upper-air temperature retrievals
A.3.2: Temperature of deep atmospheric layers
Water Vapour

Temperature is one of the fundamental state variables for which observation is essential for understanding and predicting the behaviour of the atmosphere. click for more
Passive microwave radiances
UV/VIS imager radiances
IR and microwave radiances
Limb soundings
Passive microwave radiances
UV/VIS imager radiances
IR and microwave radiances
Limb soundings
A.5.1: Total column water vapour
A.5.2: Tropospheric and lower-stratospheric profiles of water vapour
A.5.3: Upper tropospheric humidity
Wind speed and direction

The horizontal components of the atmospheric motion field are, like temperature, fundamental state variables of the system of equations that are commonly solved in the models of atmospheric behaviour used to make forecasts and climate projections. click for more
Upper-air wind retrievalsVIS/IR imager radiances
Doppler wind lidar
A.4: Upper-air wind retrievals
atmospheric · oceanic · terrestrial · top

Atmospheric - Composition

ECVGlobal Products requiring Satellite ObservationsFundamental Climate Data Records required for Product Generation (from past, current, and future missions)Product Numbers (IP-10 Reference Actions)
Aerosol

Atmospheric aerosols are minor constituents of the atmosphere by mass, but a critical component in terms of impacts on climate, and especially climate change. click for more
Aerosol optical depth
Aerosol single scattering albedo
Aerosol layer height
Aerosol extinction profiles from the troposphere to at least 35km
UV/VIS/NIR/SWIR and TIR radiances
UV/VIS/IR limb sounding (scatter, emission, occultation)
Lidar profiling
A.10.1: Aerosol optical depth
A.10.2: Aerosol single scattering albedo
A.10.3: Aerosol layer height
A.10.4: Aerosol extinction profiles from the troposphere to at least 35km
Carbon dioxide

Carbon dioxide (CO2) is a naturally occurring greenhouse gas, but one whose abundance has been increased substantially above its pre-industrial value of some 280 ppm by human activities, primarily because of emissions from combustion of fossil fuels, deforestation and other land-use change. click for more
Retrievals of greenhouse gases, such as CO2 and CH4, of sufficient quality to estimate regional sources and sinksNIR/IR radiancesA.8.1: Retrievals of CO2 and CH4 of sufficient quality to estimate regional sources and sinks
Methane

Methane (CH4) is the second most significant of the greenhouse gases that have increased in concentration in the atmosphere directly due to human activities, from the viewpoint of the radiative forcing of climate change. click for more
Retrievals of greenhouse gases, such as CO2 and CH4, of sufficient quality to estimate regional sources and sinksNIR/IR radiancesA.8.1: Retrievals of CO2 and CH4 of sufficient quality to estimate regional sources and sinks
Other long‐lived greenhouse gases

The ECV “Other long-lived greenhouse gases” refers to a set of gases additional to carbon dioxide and methane that are classified as having atmospheric lifetimes of at least a few years. click for more
Retrievals of greenhouse gases, such as CO2 and CH4, of sufficient quality to estimate regional sources and sinksNIR/IR radiancesA.8.1: Retrievals of CO2 and CH4 of sufficient quality to estimate regional sources and sinks
Ozone

Ozone (O3) is a short-lived greenhouse gas whose changes since the pre-industrial era due to emissions of precursor species contribute to a tropospheric radiative forcing that is larger than that of N20 but less than that of methane. click for more
Total column ozone
Tropospheric ozone
Ozone profiles from upper troposphere to mesosphere
UV/VIS and IR/microwave radiances, from nadir and limb soundingA.9.1: Total column ozone
A.9.2: Tropospheric ozone
A.9.3: Ozone profiles from upper troposphere to mesosphere
Precursor species

The importance of observing relatively short-lived gaseous “precursor species” that affect the distributions of ozone and aerosols through chemical interactions was stated in IP-10. click for more
Retrievals of precursors for aerosols and ozone such as NO2, SO2, HCHO and COUV/VIS/NIR/SWIR and TIR radiances UV/VIS/IR limb sounding (scatter, emission, occultation) Lidar profilingA.11.1: Retrievals of precursors for Aerosols and Ozone such as NO2, SO2, HCHO and CO
atmospheric · oceanic · terrestrial · top
Oceanic ECVs

Oceanic

6 of 18 ECVs have a significant contribution from satellite EO

Oceanic - Surface

ECVGlobal Products requiring Satellite ObservationsFundamental Climate Data Records required for Product Generation (from past, current, and future missions)Product Numbers (IP-10 Reference Actions)
Carbon dioxide partial pressure

The surface ocean partial pressure of carbon dioxide, pCO2, is a critical parameter of the oceanic inorganic carbon system (a) because it largely determines the magnitude and direction of the exchange of CO2 between the ocean and atmosphere, and (b) because it is a valuable indicator for changes in the upper ocean carbon cycle. click for more
N/AN/AN/A
Ocean acidity

The scientific and policy needs for coordinated, worldwide information-gathering on ocean acidification and its ecological impacts are now widely recognized. click for more
N/AN/AN/A
Ocean colour

Ocean colour is measured as the ocean colour radiance (OCR). click for more
Ocean colour radiometry – water leaving radiance
Oceanic chlorophyll-a concentration, derived from ocean colour radiometry
Multispectral VIS imager radiancesO.6.1: Ocean colour radiometry – water leaving radiance
O.6.2: Oceanic chlorophyll-a concentration derived from ocean colour radiometry
Phytoplankton

Climate variability significantly impacts plankton in the ocean, both the microflora (phytoplankton) and the microfauna (zooplankton), over both short (seasonal to interannual) and long (decadal) time scales. click for more
N/AN/AN/A
Sea ice

Sea ice is most often thought of as a sensitive indicator to changes in the energy absorbed by the ice. click for more
Sea-ice concentration/extent/edge, supported by sea-ice thickness and sea-ice driftPassive and active microwave and visible imager radiances, supported by Synthetic Aperture Radar (SAR) altimetryO.5: Sea-ice concentration/extent/edge, supported by Sea-ice thickness and sea-ice drift
Sea level

Changes in local sea level are important to coastal communities. click for more
Sea level global mean and regional variabilityAltimetryO.3: Sea level global mean and regional variability
Sea state

Waves are generated by ocean surface vector stress and evolve from wind waves to swell when the stress has insufficient magnitude to support the waves. click for more
Wave height, supported by other measures of sea state (wave direction, wavelength, time period)AltimetryO.4: Wave height, supported by other measures of sea state (wave direction, wavelength, and time period)
Sea-surface salinity (SSS)

Salinity is the fraction of water that is comprised of salt and other impurities. click for more
Datasets for research on identification of changes in sea-surface salinityMicrowave radiancesO.2: Datasets for research on identification of changes in sea-surface salinity
Sea-surface temperature (SST)

The large-scale spatial patterns of sea-surface temperature (SST) are related to large-scale weather patterns. click for more
Integrated sea-surface temperature analyses based on satellite and in situ data recordsSingle and multi-view IR and microwave imager radiancesO.1: Integrated sea-surface temperature analyses based on satellite and in situ data records
Surface current

Surface currents span a wide range of space and time scales, from basin-wide motions to mesoscale eddies with scales greater than 100 km, fast narrow currents of the order of 100 km wide, sub- mesoscale features down to the kilometre scale, and finally down to turbulence scales of less than one metre. click for more
N/AN/AN/A
atmospheric · oceanic · terrestrial · top

Oceanic - Sub-surface

ECVGlobal Products requiring Satellite ObservationsFundamental Climate Data Records required for Product Generation (from past, current, and future missions)Product Numbers (IP-10 Reference Actions)
Carbon dioxide partial pressure

The oceanic uptake of anthropogenic carbon is a key element of the planetary carbon budget. click for more
N/AN/AN/A
Current

Oceanic measurements of sub-surface ocean velocity provide the data needed for estimates of ocean transports of mass, heat, freshwater and other properties on basin to global scales. click for more
N/AN/AN/A
Nutrients

It became clear over the last decade that it is necessary to develop accurate observations of trends in dissolved nutrients in both upper- and deep-ocean waters. click for more
N/AN/AN/A
Ocean acidity

The scientific and policy needs for coordinated, worldwide information-gathering on ocean acidification and its ecological impacts are now widely recognized. click for more
N/AN/AN/A
Oxygen

Oxygen is essential for all higher life. click for more
N/AN/AN/A
Salinity

Oceanic observations of sub-surface salinity are required for estimating ocean transports of freshwater and other properties on basin to global scales. click for more
N/AN/AN/A
Temperature

Sub-surface temperature is a fundamental variable required to monitor variability and change in the physical environment of the ocean, energy flows, climate patterns and sea level, and is essential to the understanding of changes in many other variables in the realms of marine biogeochemistry and biology. click for more
N/AN/AN/A
Tracers

Ocean tracers are essential for identifying anthropogenic carbon uptake, storage, and transport in the ocean, as well as for understanding multi-year ocean ventilation, long-term mixing and ocean circulation and thereby for providing essential validation information for climate-change models. click for more
N/AN/AN/A
atmospheric · oceanic · terrestrial · top
Terrestrial ECVs

Terrestrial

11 of 16 ECVs have a significant contribution from satellite EO

ECVGlobal Products requiring Satellite ObservationsFundamental Climate Data Records required for Product Generation (from past, current, and future missions)Product Numbers (IP-10 Reference Actions)
Above-ground biomass

Vegetation biomass is a crucial ecological variable for understanding the evolution and potential future changes of the climate system. click for more
Regional and global above-ground forest biomassLong-wavelength radar and lidarT.9: Regional and global above-ground forest biomass
Albedo

The albedo of a land surface is the non-dimensional ratio of the radiation flux reflected by a (typically horizontal) surface in all directions and the incoming irradiance, which is the radiation flux from the upper hemisphere. click for more
Reflectance anisotropy (BRDF), black- sky and white-sky albedoMultispectral and multiangular imager radiancesT.5: Reflectance anisotropy (BRDF), black-sky and spectral white-sky albedo
Fire disturbance

Fires have impact on several identified radiative forcing agents. click for more
Maps of burnt area, supplemented by active-fire maps and fire-radiative powerVIS/NIR/SWIR/TIR moderate- resolution multispectral imager radiancesT.10: Maps of burnt area, supplemented by active-fire maps and fire-radiative power
Fraction of absorbed photosynthetically active radiation (FAPAR)

Solar radiation in the spectral range from 400 to 700nm, known as Photosynthetically Active Radiation (PAR), provides the energy required by terrestrial vegetation to produce organic materials from mineral components. click for more
Maps of the Fraction of Absorbed Photosynthetically Active RadiationVIS/NIR multispectral imager radiancesT.7: Maps of the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR)
Glaciers and ice caps

This ECV was termed “Glaciers and ice caps” in IP-10, but here the term “Glacier” is used more generally, to include ice caps. click for more
2D vector outlines of glaciers and ice caps (delineating glacier area), supplemented by digital elevation models for drainage divides and topographic parametersHigh-resolution VIS/NIR/SWIR optical imager radiances, supplemented by microwave InSAR and along-track optical stereo imagingT.3.1: 2D vector outlines of glaciers and ice caps (delineating glacier area), supplemented by digital elevation models for drainage divides and topographic parameters
T.3.2: Elevation change of glaciers and ice caps, from geodetic methods, in regions where outlines are available
Groundwater

It is estimated that groundwater accounts for around 30% of the world’s total freshwater resources, including those locked in snow and ice, and is by far the largest available reservoir of liquid freshwater. click for more
N/AN/AN/A
Ice sheets

Our understanding of the timescale of ice sheet response to climate change has changed dramatically over the last decade. click for more
Ice-sheet elevation changes, supplemented by fields of ice velocity and ice-mass changeRadar and laser altimetry, supplemented by SAR, gravityT.4: Ice-sheet elevation changes, supplemented by fields of ice velocity and ice mass change
Lakes

Information on changes in lake level and area (which are surrogates for changes in lake volume) is required on a monthly basis for climate assessment purposes. click for more
Lake levels and areas of lakes in the Global Terrestrial Network for Lakes (GTN-L)VIS/NIR imager radiances, and radar imager radiances
Altimetry
T.1.1: Areas of lakes in the Global Terrestrial Network for Lakes (GTN-L)
T.1.2: Lake level of all lakes in the Global Terrestrial Network for Lakes (GTN-L)
Land cover

Land cover influences climate by modifying water and energy exchanges with the atmosphere and by changing greenhouse gas and aerosol sources and sinks. click for more
Moderate-resolution maps of land- cover type
High-resolution maps of land-cover type, for the detection of land-cover change
Moderate-resolution multispectral VIS/NIR imager radiances
High-resolution multispectral VIS/NIR imager radiances, supplemented by radar
T.6.1: Moderate-resolution maps of land-cover type
T.6.2: High-resolution maps of land-cover type, for the detection of land-cover change
Leaf area index (LAI)

The Leaf Area Index (LAI) of a plant canopy or ecosystem, defined as one half the total green leaf area per unit horizontal ground surface area, measures the area of leaf material present in the specified environment. click for more
Maps of Leaf Area IndexVIS/NIR multispectral imager radiancesT.8: Maps of Leaf Area Index
Permafrost

The properties of frozen ground react sensitively to climate and environmental change in high- latitude and high-altitude regions. click for more
N/AN/AN/A
River discharge

River discharge measurements have essential direct applications for water management and related services, including flood protection. click for more
N/AN/AN/A
Snow cover

Terrestrial snow properties are highly sensitive to changes in temperature and precipitation regimes and are recognised to provide a fundamental indicator of climate variability and change. click for more
Snow areal extent, supplemented by snow water equivalentModerate-resolution VIS/NIR/IR and passive microwave imager radiancesT.2: Snow areal extent, supplemented by snow water equivalent
Soil carbon

Carbon in soils occurs in organic and inorganic forms. click for more
N/AN/AN/A
Soil moisture

Soil moisture is an important variable in land-atmosphere feedbacks at both weather and climate time scales. click for more
Research towards global near-surface soil-moisture map (up to 10cm soil depth)Active and passive microwaveT.11: Global near-surface soil moisture maps (up to 5cm soil depth)
Water use

Data on water extractions and available renewable freshwater provide key information on the availability of freshwater and the amount of water stress in a country. click for more
N/AN/AN/A
atmospheric · oceanic · terrestrial · top
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