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CEOS EO HANDBOOK –
EARTH OBSERVATION SATELLITE CAPABILITIES AND PLANS
Capabilities of Earth Observation Satellites
   
Atmospheric Chemistry Instruments
Atmospheric Temperature and Humidity Sounders
Cloud Profile and Rain Radars
Earth Radiation Budget Radiometers
High Resolution Optical Imagers
Imaging Multi-Spectral Radiometers (vis/IR)
Imaging Multi-Spectral Radiometers (Passive Microwave)
Imaging Microwave Radars
Lidars
Multiple Direction/ Polarisation Instruments
Ocean Colour Instruments
Radar Altimeters
Scatterometers
Gravity, Magnetic Field and Geodynamic instruments
  Earth Observation Plans by Measurement  
Catalogue of Satellite Missions
Catalogue of Satellite Instruments
 



ATMOSPHERIC CHEMISTRY INSTRUMENTS
Description
‘Atmospheric chemistry instruments’ is used here to describe a range of different types of instruments that use various techniques and different parts of the electromagnetic spectrum to undertake measurements of the atmosphere’s composition. Each atmospheric gas is characterised by its ‘absorption’ and ‘emission’ spectra, which describe how the molecules respond to different frequencies of radiation. Remote sensing instruments exploit these ‘signatures’ to provide information on atmospheric composition, using measurements over a range of wavelengths, between UV and microwave.

Atmospheric absorption tends to be dominated by water vapour, carbon dioxide, and ozone, with smaller contributions from methane and other trace gases. Relatively broadband instruments can be used for measurements of the dominant gases, but high spectral resolution sensors are needed to make measurements of other species, since they produce weaker signals, and these must be discriminated from the signals from more abundant gases.

The instruments are typically operated in either:

— nadir-viewing mode: looking directly down to measure the radiation emitted or scattered in a small solid angle centred around a measurement point on the Earth, with resulting high spatial resolution in the horizontal direction, but limited vertical resolution; or

— limb-viewing mode: scanning of positions beyond the horizon to observe paths through the atmosphere at a range of altitudes – providing high vertical resolution (a few km) but limited horizontal resolution (tens of km at best) and particularly useful for studying the middle atmosphere.

Emission or absorption spectra can be studied in limb-viewing mode. One approach – known as occultation – uses known astronomical bodies (such as the Sun and stars) as well characterised target sources, and measures the effect of the Earth’s atmosphere on the radiation reaching the satellite to determine atmospheric composition.

Applications
The earliest atmospheric chemistry instruments were deployed to help understanding of stratospheric ozone depletion. They succeeded in producing startling and convincing evidence of the growth of the Antarctic ozone hole. Many of the current and planned instruments continue to provide more sophisticated and accurate information on ozone chemistry in the atmosphere, including data related to gases and radicals which impact on the ozone cycle.

Agencies are addressing the need for sustained measurements of other key atmospheric constituents including CO2, CO and CH4. Research missions are also planned periodically to allow detailed examination of the complex details of atmospheric chemistry and the possibility that such details might be changing. The capability to provide a global picture of the atmosphere, and how it is changing on a daily, seasonal and geographical basis, is ensuring demand for these instruments in a wide range of applications. These include: pollution monitoring; climatology, including studies of the carbon cycle and support to policy-making processes such as the Kyoto Protocol; volcanic eruption monitoring; and operational meteorology.
Current and planned Instruments
ACE-FTS OMPS
CO Sensor (ASCENDS) OSIRIS
GAMI PCW PHEMOS-Atmospheric
GEMS SAGE-III
GOME-2 SBUV/2
GOMOS SCIAMACHY
HiRDLS SMILES
IASI SMR
IPDA LIDAR Spectrometer (OCO-2)
IR Spectrometer (GACM) TANSO-FTS
Mach-Zehnder Micro-interferometer TES
MAESTRO UC Sepctrometer (GACM)
Microwave limb sounder (GACM) UVAS
MIPAS UVN (Sentinel-4)
MOPITT UVNS (Sentinel-5 precursor)
OMI UVNS (Sentinel-5)
Atmospheric transmittance and radiance for UV to IR regions.
A global air pollution (nitrogen dioxide) map produced by SCIAMACHY on Envisat.
The trend towards improved measurement resolutions and accuracies, profiling measurements (rather than total column measurements), and extended capability in the
 
Upper Troposphere/Lower Stratosphere (UTLS) will further extend the value of these instruments in the coming years for monitoring air quality and modelling atmospheric processes.
Further Information
ACE-FTS: www.ace.uwaterloo.ca
GOMOS/MIPAS/SCIAMACHY: envisat.esa.int/instruments/index.html
GOSAT: http://www.jaxa.jp/projects/sat/gosat/index_e.html
IASI: smsc.cnes.fr/IASI/
HIRDLS/MLS/OMI/TES: eos-aura.gsfc.nasa.gov/instruments/
 

 

 

 

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