CEOS EO HANDBOOK – MEASUREMENT INSTRUMENTS
Measurements > Atmosphere >
Atmospheric Humidity Fields >
Atmospheric specific humidity (column/profile)


Measurement Definition*: Vertical profile of the specific humidity in the atmosphere - Requested from surface to TOA (layers: LT, HT, LS, HS&M) + Total column - Physical units: [ g/kg ] for profile, [ kg/m2 ] for total column - Accuracy unit: [ % ] for profile, [ kg/m2 ] for total column.

Thematic Links
InstrumentStatus/
Accuracy
Instrument DescriptionMeasurement TechnologyTimeline
AIRS
Atmospheric Infra-red Sounder
Operational
High spectral resolution measurement of temperature and humidity profiles in the atmosphere. Long-wave Earth surface emissivity. Cloud diagnostics. Trace gas profiles. Surface temperatures.n/a
AltiKa
Ka-band Altimeter
Operational
Sea surface height.n/a
AMI
Advanced Meteorological Imager
Operational
Continuous monitoring capability for the near real-time generation of high-resolution meteorological products and long-term change analysis of land/sea surface temperature and cloud coverage.n/a
AMR
Advanced Microwave Radiometer
Operational
Altimeter data to correct for errors caused by water vapour and cloud-cover. Also measures total water vapour and brightness temperature.n/a
AMR-C
Advanced Microwave Radiometer for Climate
Operational
Capabilities of the AMR with the addition of an on-board calibrator for high stability wet-tropospheric path delay correction.n/a
AMSR2
Advanced Microwave Scanning Radiometer 2
Operational
+/-1.5 kg/m2
Measurements of water vapour, cloud liquid water, precipitation, winds, sea surface temperature, sea ice concentration, snow cover, soil moisture.n/a
AMSU-A
Advanced Microwave Sounding Unit-A
Operational
All-weather night-day temperature sounding to an altitude of 45 km.n/a
AMSU-A
Advanced Microwave Sounding Unit-A
Operational
All-weather night-day temperature sounding to an altitude of 45 km. AMSU-A on Aqua is still partially operational, with 9 of the 15 channels working and collecting data.n/a
ASI
Atmospheric Sounding Interferometer
Operational
Atmospheric sounding for weather forecasting.n/a
ATMS
Advanced Technology Microwave Sounder
Operational
Collects microwave radiance data that when combined with the CrIS data will permit calculation of atmospheric temperature and water vapour profiles.n/a
CrIS
Cross-track Infrared Sounder
Operational
Daily measurements of vertical atmospheric distribution of temperature, moisture, and pressure. MWIR non-operational on Suomi NPP effective 12 July 2021.n/a
GIIRS
Geostationary Interferometric Infrared Sounder
Operational
Measurements of three dimensional atmospheric structure. Large-area, continuous, fast, and accurate vertical air soundings of temperature and humidity. Subsequent units have slightly different specifications.n/a
GMI
GPM Microwave Imager
Operational
Measures rainfall rates over oceans and land, combined rainfall structure and surface rainfall rates with associated latent heating. Used to produce three hour, daily, and monthly total rainfall maps over oceans and land.n/a
GNOS
GNSS Radio Occultation Sounder
Operational
Atmospheric sounding for weather forecasting.n/a
GNSS-RO Receiver
Global Navigation Satellite Systems (GNSS)- Radio Occultation (RO) Receiver
Operational
Measurement of bending angles of GNSS satellite signals occulted by Earth's atmosphere for retrieval of temperature and humidity profiles.n/a
GOME-2
Global Ozone Monitoring Experiment - 2
Operational
Measurement of total column amounts and stratospheric and tropospheric profiles of ozone. Also amounts of H20, NO2, OClO, BrO, SO2 and HCHO.n/a
GPSRO (Terra-SAR)
GPS Radio Occultation System
Operational
Measurements of atmospheric temperature, pressure and water vapour content.n/a
GRAS
Global Navigation Satellite Systems (GNSS) Receiver for Atmospheric Sounding
Operational
GNSS receiver for atmospheric temperature and humidity profile sounding.n/a
HIRAS
Hyperspectral Infrared Atmospheric Sounder
Operational
 n/a
HIRS/4
High Resolution Infra-red Sounder/4
Operational
Atmospheric temperature profiles and data on cloud parameters, humidity soundings, water vapour, total ozone content, and surface temperatures. Same as HIRS/3, with 10 km IFOV.n/a
IASI
Infrared Atmospheric Sounding Interferometer
Operational
+/-10 %
Measures tropospheric moisture and temperature, column integrated contents of ozone, carbon monoxide, methane, nitrous oxide and other minor gases which affect tropospheric chemistry. Also measures sea surface and land temperature.n/a
IKFS-2
IR-Fourier spectrometer
Operational
Atmospheric temperature/humidity profiles, data on cloud parameters, water vapour & ozone column amounts, surface temperature.n/a
IRAS
InfraRed Atmospheric Sounder
Operational
Atmospheric sounding for weather forecasting.n/a
MAESTRO
Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation
Operational
Chemical processes involved in the depletion of the ozone layer, and now including a high quality water vapour data product.n/a
MHS
Microwave Humidity Sounder
Operational
Atmospheric humidity profiles, cloud cover, cloud liquid, water content, ice boundaries and precipitation data. MHS on NOAA-18 is considered failed following an anomaly on 21 October 2018.n/a
MLS (EOS-Aura)
Microwave Limb Sounder (EOS-Aura)
Operational
Measures lower stratospheric temperature and concentration of H2O, O3, ClO, HCl, OH, HNO3, N2O and SO2.n/a
MODIS
MODerate-Resolution Imaging Spectroradiometer
Operational
Data on biological and physical processes on the surface of the Earth and in the lower atmosphere, and on global dynamics. Surface temperatures of land and ocean, chlorophyll fluorescence, land cover measurements, cloud cover (day and night).n/a
MSU-GS
Multispectral scanning imager-radiometer
Operational
Measurements of cloud cover, cloud top height, precipitation, cloud motion, albedo, vegetation, convection, air mass analysis, tropopause monitoring, stability monitoring, total ozone and surface temperature, fire detection.n/a
MSU-GS/VE
Multispectral scanning imager-radiometer
Operational
Operational metrology, hydrology, climate monitoring and environmental monitoringn/a
MTVZA-GY
Scanning microwave imager-sounder
Operational
Atmospheric temperature and humidity profiles, precipitation, sea-level wind speed, snow/ice coverage.n/a
MWHS-2
Improved MicroWave Humidity Sounder
Operational
Meteorological applications.n/a
MWRI
Micro-Wave Radiation Imager
Operational
All weather observations of precipitation, cloud features, vegetation, soil moisture sea ice, etc.n/a
MWRI
Microwave Radiometer Imager
Operational
Ocean wind and temperature measurements.n/a
MWTS-2
Micro-Wave Temperature Sounder-2
Operational
Atmospheric sounding measurements.n/a
SAGE-III
Stratospheric Aerosol and Gas Experiment
Operational
Limb-viewing measurements of aerosol, O3, H20, NO2, OClO, NO3, temperature and pressure in the stratosphere, upper troposphere, and mesosphere using solar occultation, lunar occultation and limb scatter measurement techniques.n/a
SEVIRI
Spinning Enhanced Visible and Infra-Red Imager
Operational
Measurements of cloud cover, cloud top height, precipitation, cloud motion, vegetation, radiation fluxes, convection, air mass analysis, cirrus cloud discrimination, tropopause monitoring, stability monitoring, total ozone and sea surface temperature.n/a
SMR
Submillimetre Radiometer
Operational
Measures global distributions of ozone and species of importance for ozone chemistry ClO, HNO3, H2O, N2O, (HO2, H2O2). Measures temperature in the height range 15 - 100 km.n/a
Sounder
Sounder
Operational
Atmospheric soundings and data on atmospheric stability and thermal gradient winds.n/a
Sounder (INSAT)
IR Sounder
Operational
Atmospheric soundings, atmospheric stability, thermal gradient winds.n/a
SRAL
SAR Radar Altimeter
Operational
Marine and land services.n/a
SSM/IS
Special Sensor Microwave Imager Sounder
Operational
Measures thermal microwave radiation. Global measurements of air temp profile, humidity profile, ocean surface winds, rain overland/ocean, ice concentration/age, ice/snow edge, water vapour/clouds over ocean, snow water content, land surface temperature.n/a
TEMPEST
Temporal Experiment for Storms and Tropical Systems
Operational
Hosted on the ISS, TEMPEST measures atmospheric humidityn/a
TGRS
TriG (Tri-GNSS) GNSS Radio-occultation System
Operational
TGRS is the radio occultation receiver, which will receive signals from GPS, Galileo, and Glonass.n/a
TOR
Tracking, Occultation and Ranging
Operational
Consists of the dual-frequency GPS receiver IGOR (Integrated GPS Occultation Receiver) for evaluation of GPS-based orbit data as an independent tracking techniquen/a
TROPICS
Microwave Spectrometer (TROPICS)
Operational
+/-0.25
Constellation to provide temperature/moisture sounding and cloud/precipitation imaging with rapid update.n/a
UVNS (Sentinel-5 precursor)
TROPOMI
Operational
Supporting atmospheric composition and air quality monitoring services.n/a
AMR-S
AMR-S Two-Beam Microwave Radiometer
Being developed
Capabilities of the AMR with the addition of a 2nd beam to provide wet-tropospheric path delay correction within both swaths of the primary radar instrument (KaRIn)n/a
AMSR3
Advanced Microwave Scanning Radiometer 3
Being developed
Measurements of water vapour, cloud liquid water, precipitation including snowfall, winds, sea surface temperature, sea ice concentration, snow cover, soil moisture.n/a
AWS Instrument
Arctic Weather Satellite Microwave Radiometer
Being developed
Cross-track scanning microwave radiometer. Provides measurements of atmospheric humidity and temperature.n/a
FCI
Flexible Combined Imager
Being developed
Measurements of cloud cover, cloud top height, precipitation, cloud motion, vegetation, radiation fluxes, convection, air mass analysis, cirrus cloud discrimination, tropopause monitoring, stability monitoring, total ozone and sea surface temperature.n/a
GEOXO Sounder
GEO Extended Operations Hyperspectral Infrared Sounder
Being developed
 n/a
HyperCube Instrument
HyperCube Instrument
Being developed
Designed to measure the speed, direction, and elevation of wind in Earth's atmosphere. Contains more vertical layers of wind vector data at fine spatial resolution, resulting in more accurate data than other available solutions.n/a
IASI-NG
Infrared Atmospheric Sounding Interferometer - New Generation
Being developed
+/-5 %
Measures profiles of atmospheric temperature, humidity, ozone, carbon monoxide, columns of methane, nitrous oxide, and other minor gases, and sea, ice, and land surface temperature and emissivity. Provides information on aeorols and cloud: fractional coverage, phase, cloud top height (input to Polar AMVs) and particle size. Prime applications: NWP, AC/AQ, climate. Secondary applications: NWC, land/ocean surface monitoring. IASI-NG will resume IASI role as internationl standard for satellite inter-calibration (GSICS).n/a
IRIS
Interferometric Radar Altimeter for Ice and Snow
Being developed
Ku-band Interferometric Synthetic Aperture Radar Altimeter (with added Ka-band channel for snow depth retrieval and in combination with AMR-CR MW Radiometer for ice&snow classification and wet troposphere correction) to cover the needs for continuous monitoring of the sea ice thickness and land ice elevation measurement after Cryosat-2 with enhanced performance.n/a
IRS
Infra-Red Sounder
Being developed
Measurements of vertically resolved clear sky atmospheric motion vectors, temperature and water vapour profiles.n/a
MWS
Microwave Sounder
Being developed
All-weather night-day temperature soundingn/a
RO
RO
Being developed
GNSS receiver for atmospheric temperature and humidity profile sounding.n/a
UVNS (Sentinel-5)
Ultra-violet Visible Near-infrared Shortwave-infrared spectrometer
Being developed
Supporting atmospheric composition and air quality monitoring services. Measurements of atmospheric trace gases, primarily O3, NO2, SO2, HCHO, CH4 and CO.n/a
GHMS
Geostationary HiMawari Sounder
Approved
 n/a
MVIRS
Moderate Resolution Visible and Infrared Imaging Spectroradiometer
Approved
Measures surface temperature and cloud and ice cover. Used for snow and flood monitoring and surface temperature.n/a
UVN
UV-VIS-NIR Sounder
Approved
Measurements of atmospheric trace gases, mainly O3, NO2, SO2, H2CO. The product list is not yet approved, the accuracy summary column lists the breakthrough user requirements.n/a
Advanced Radiomet
Advanced Radio-occultation receiver
Proposed
Atmospheric temperature and humidity profiles with high vertical resolution.n/a
IKFS-3
Advanced Fourier spectrometer
Proposed
Atmospheric temperature/humidity profiles, data on cloud parameters, water vapour & ozone column amounts, surface temperature.n/a
MTVZA-GY-MP
Advanced Scanning microwave imager-sounder
Proposed
Atmospheric temperature and humidity profiles, precipitation, sea-level wind speed, snow/ice coverage.n/a
AMSR-E
Advanced Microwave Scanning Radiometer-EOS
No longer operational
+/-3.5 kg/m2
Measurements of water vapour, cloud liquid water, precipitation, winds, sea surface temperature, sea ice concentration, snow cover and soil moisture. Instrument stopped functioning 4th October 2011.n/a
AOPOD
Atmosphere Occultation and Precision Orbit Determination
No longer operational
A spaceborne dual-frequency GPS receiver for Precision Orbit Determination (POD) and GPS radio occultation (RO) measurements n/a
HiRDLS
High Resolution Dynamics Limb Sounder
No longer operational
Measures atmospheric temperature, concentrations of ozone, water vapour, methane, NOx, N2O, CFCs and other minor species, aerosol concentration, location of polar stratospheric clouds and cloud tops. Currently not collecting data on Aqua.n/a
HSB
Humidity Sounder for Brazil
No longer operational
Humidity soundings for climatological and atmospheric dynamics applications. The scan mirror motor failed on the 5th of February 2003.n/a
TES
Tropospheric Emission Spectrometer
No longer operational
3D profiles on a global scale of all infra-red active species from surface to lower stratosphere. Measures greenhouse gas concentrations, tropospheric ozone, acid rain precursors, gas exchange leading to stratospheric ozone depletion.n/a
* Description adapted from WMO.