Global Ozone Monitoring by Occultation of Stars (GOMOS), is an
instrument on board the European
satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...
Envisat launched 1 March 2002. It is the first space instrument dedicated to the study of the
atmosphere of the Earth by the technique of stellar
occultation
An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...
. The spectrum of stars in the
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
,
visible and the
near infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from arou ...
parts of the
electromagnetic spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.
The electromagnetic spectrum covers electromagnetic waves with frequencies ranging fro ...
is observed. It is aimed to use GOMOS to build a
climatology
Climatology (from Greek , ''klima'', "place, zone"; and , ''-logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of study ...
of
ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
and related species in the middle atmosphere (15 to 100 km).
Instrument details
The 250-680
nm spectral domain is used for the determination of
O3,
NO2,
NO3−,
aerosols and
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer.
Thermometers are calibrated in various Conversion of units of temperature, temp ...
. In addition, two high spectral resolution channels centred at 760 and 940 nm allow measurements of
O2 and
H2O and two fast
photometer
A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, ...
s are used to correct star scintillation perturbations and to determine high vertical resolution temperature profiles.
Global latitude coverage is obtained with up to 40 stellar occultations per
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...
from South Pole to North Pole. Data acquired on dark limb (night-time) are of better quality than on bright limb (day-time) because of a smaller perturbation by background light.
History
GOMOS was first proposed in 1988 as an Announcement of Opportunity instrument dedicated to be a part of the Earth Observation Polar Platform Mission, the former name of Envisat. In 1992 it was decided that GOMOS would be developed as a
European Space Agency-funded instrument.
See also
External links
Official ESA GOMOS pageGOMOS page
from DLR
Ozone
Spacecraft instruments
{{space-stub