Global Ozone Monitoring by Occultation of Stars
Encyclopedia
Global Ozone Monitoring by Occultation of Stars (GOMOS), is an instrument
on board the European satellite
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
. The spectrum of stars in the ultraviolet
, visible and the near infrared parts of the electromagnetic spectrum
is observed. It is aimed to use GOMOS to build a climatology
of ozone
and related species in the middle atmosphere (15 to 100 km).
, NO2
, NO3−
, aerosols and temperature
. In addition, two high spectral resolution channels centred at 760 and 940 nm allow measurements of O2
and H2O
and two fast photometer
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
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.
-funded instrument.
Measuring instrument
In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item...
on board the European satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
Envisat
Envisat
Envisat is an Earth-observing satellite. It was launched on 1 March 2002 aboard an Ariane 5 from the Guyana Space Centre in Kourou, French Guyana into a Sun synchronous polar orbit at an altitude of...
launched 1 March 2002. It is the first space instrument dedicated to the study of the atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
of the Earth by the technique of stellar occultation
Occultation
An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...
. The spectrum of stars in the ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
, visible and the near infrared parts of the electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
is observed. It is aimed to use GOMOS to build a climatology
Climatology
Climatology is the study of climate, scientifically defined as weather conditions averaged over a period of time, and is a branch of the atmospheric sciences...
of ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
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 O3Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
, NO2
Nitrogen dioxide
Nitrogen dioxide is the chemical compound with the formula it is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent...
, NO3−
Nitrate
The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
, aerosols and temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
. In addition, two high spectral resolution channels centred at 760 and 940 nm allow measurements of O2
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and H2O
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
and two fast photometer
Photometer
In its widest sense, a photometer is an instrument for measuring light intensity or optical properties of solutions or surfaces. Photometers are used to measure:*Illuminance*Irradiance*Light absorption*Scattering of light*Reflection of light*Fluorescence...
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
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
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 AgencyEuropean Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
-funded instrument.
External links
- Official ESA GOMOS page
- GOMOS page from DLRGerman Aerospace CenterThe German Aerospace Center is the national centre for aerospace, energy and transportation research of the Federal Republic of Germany. It has multiple locations throughout Germany. Its headquarters are located in Cologne. It is engaged in a wide range of research and development projects in...