CEOS EO HANDBOOK – MEASUREMENT INSTRUMENTS
Measurements > Atmosphere >
Aerosols >
Aerosol absorption optical depth (column/profile)


Measurement Definition*: Optical depth (OD) is the integral of extinction in the vertical dimension (integral of extinction (km-1) dz). The transmittance of the atmosphere = T = Exp(-OD) = Exp(-Integral(extinction dz)).
InstrumentStatus/
Accuracy
Instrument DescriptionMeasurement TechnologyTimeline
ACE-FTS
Atmospheric Chemistry Experiment (ACE) Fourier Transform Spectrometer
Operational
Measure and understand the chemical processes that control the distribution of ozone in the Earth's atmosphere, especially at high altitudes.n/a
AVHRR/3
Advanced Very High Resolution Radiometer/3
Operational
Measurements of land and sea surface temperature, cloud cover, snow and ice cover, soil moisture and vegetation indices. Data also used for volcanic eruption monitoring.Multi-purpose imaging Vis/IR radiometer
GEMS
Geostationary Environment Monitoring Spectrometer
Operational
Measurements of atmospheric chemistry, precursors of aerosols and ozone in particular, in high temporal and spatial resolution over Asia.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.High-resolution nadir-scanning SW spectrometer
MISR
Multi-angle Imaging SpectroRadiometer
Operational
Measurements of global surface albedo, aerosol and vegetation properties. Also provides multi-angle bidirectional data (1% angle-to-angle accuracy) for cloud cover and reflectances at the surface and aerosol opacities. Global and local modes.Multi-channel/direction/polarisation radiometer
OMI
Ozone Measuring Instrument
Operational
Mapping of ozone columns, key air quality components (NO2, SO2, BrO, OClO and aerosols), measurements of cloud pressure and coverage, global distribution and trends in UV-B radiation.High-resolution nadir-scanning SW spectrometer
OSIRIS
Optical Spectrograph and Infra-Red Imaging System
Operational
Detects aerosol layers and abundance of species such as O3, NO2, OClO, BrO and NO. Consists of spectrograph and IR imager.Limb-scanning SW spectrometer
Sounder
Sounder
Operational
Atmospheric soundings and data on atmospheric stability and thermal gradient winds.n/a
UVNS (Sentinel-5 precursor)
TROPOMI
Operational
Supporting atmospheric composition and air quality monitoring services.High-resolution nadir-scanning SW spectrometer
VIIRS
Visible/Infrared Imager Radiometer Suite
Operational
Global observations of land, ocean, and atmosphere parameters: cloud/weather imagery, sea-surface temperature, ocean colour, land surface vegetation indices.Multi-purpose imaging Vis/IR radiometer
CWFMS
Canadian Wildland Fire Monitoring Sensor
Being developed
Measurements are: Fire Radiative Power (FRP), hotspot locations, rate of spread, burned area mapping. Data products generated: 1) Fire maps, showing location, extent, and timing of forest fire events; 2) Fire characteristics, such as fire line intensity, rate of spread and fuel consumption; 3) Plume dynamics through smoke transport maps and plume heights; 4) Mass of carbon released into atmosphere.Multi-purpose imaging Vis/IR radiometer
SPEXone
Spectro-Polarimeter for Exploration
Being developed
Polarimeter for measuring aerosol optical properties, clouds and aerosol types. Multi-angle spectro-polarimetry by spectral modulation technology. Distribution and detailed micro-phyiscal properties of atmospheric aerosol. Direct and indirect aerosol radiative forcing and their impact on climate.Multi-channel/direction/polarisation radiometer
GHMS
Geostationary HiMawari Sounder
Approved
 n/a
MAIA
Multi-Angle Imager for Aerosols
Approved
+/-0.05
Pushbroom spectropolarimetric camera on a 2-axis gimbal for multiangle viewing, frequent revisits over targets, and inflight calibration. Major metropolitan areas are sampled with sub-km spatial resolution to study impacts of different types of particulate matter on human health.Multi-channel/direction/polarisation radiometer
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.High-resolution nadir-scanning SW spectrometer
UVN (Sentinel-4)
UV-visible- near infrared imaging spectrometer (Sentinel-4)
Proposed
Supporting atmospheric composition and air quality monitoring services.High-resolution nadir-scanning SW spectrometer
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
* Description adapted from WMO.