GOME-2

The Global Ozone Monitoring Experiment–2 (GOME-2) is used to get a detailed picture of the total atmospheric content of ozone and the vertical ozone profile in the atmosphere.

GOME instrument

It also provides accurate information on the total column amount of nitrogen dioxide, sulphur dioxide, water vapour, oxygen/oxygen dimmer, bromine oxide and other trace gases, as well as aerosols.

Measuring global water vapour and formaldehyde

What is GOME-2?

The Global Ozone Monitoring Experiment–2 (GOME-2) is an optical spectrometer, fed by a scan mirror which enables across-track scanning in nadir, as well as sideways viewing for polar coverage and instrument characterisation measurements using the Moon.

GOME-2 Summary Budget

GOME-2 senses the Earth’s backscattered radiance and extraterrestrial solar irradiance, in the ultraviolet and visible part of the spectrum (240-790 nm), at a high spectral resolution, between 0.2–0.4 nm. 4096 spectral points from four detector channels are transferred per individual GOME-2 measurement.

Graphic of a chart showing GOME-2 transmittance

The footprint size is 80 x 40 km for main channel data. The instrument also measures the state of linear polarisation of the backscattered earthshine radiances in two perpendicular directions.

The polarisation data is down-linked in 15 spectral bands covering the region from 312 to 800 nm for both polarisation directions with a footprint of 10 x 40 km.

For a more detailed description, see the GOME-2 Product Guide, ESA's GOME-2 page or the GOME-2 Instrument Factsheet (PDF, 433 KB).

Instrument performance, product quality monitoring and further information regarding GOME-2 are provided on the GOME-2 Product Quality Monitoring page, and in the GOME-2 newsletter.

The GOME-2 instrument is developed by SELEX Galileo in Florence, Italy, under a joint contract from EUMETSAT and ESA.

Measuring global water vapour and formaldehyde

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The Global Ozone Monitoring Experiment-2 (GOME-2) delivera operational information on the total amount of water vapour and formaldehyde.

Atmospheric water vapour (H2O) is the most important natural (as opposed to man-made) greenhouse gas, accounting for about two-thirds of the natural greenhouse effect. Despite this importance, its role in climate and its reaction to climate change are still difficult to assess.

Many details of the hydrological cycle are poorly understood, such as the process of cloud formation and the transport and release of latent heat contained in the water vapour.

In contrast to other important greenhouse gases like carbon dioxide (CO2) and methane, water vapour has a much higher temporal and spatial variability.

Global monitoring of H2O by Metop is a key to understanding its impact on climate.

Formaldehyde (HCHO) is one of the most abundant hydrocarbons in the atmosphere and is an important indicator of so-called non-methane volatile organic compound (NMVOC) emissions and photochemical activity. As such, it is an indicator of the presence of volatile organic compounds in the atmosphere, which in turn play an important role in the formation of toxic ozone close to the surface and also have an important influence on climate through the formation of large aerosol particles. HCHO is a primary emission product from biomass burning and fossil fuel combustion, but its principle source in the atmosphere is the photochemical oxidation of methane and non-methane hydrocarbons. Metop-A measurements of HCHO can be used to constrain NMVOC emissions in current state-of-the-art chemical transport models used in the forecasting and analysis of pollution events and also in modelling climate change.

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Operational GOME-2 H2O and HCHO data are being produced by the Deutsches Zentrum für Luft- und Raumfahrt (DLR), the German Aerospace Center, a partner of EUMETSAT’s Ozone and Atmospheric Chemistry Monitoring SAF (O3M-SAF) coordinated by the Finnish Meteorological Institute. The H2O and HCHO retrieval algorithms for GOME-2 have been developed by the Max Planck Institute for Chemistry in Mainz, Germany, and the Belgian Institute for Space Aeronomy (BIRA/IASB) in Brussels, respectively.

GOME-2 H2O and HCHO as well as other operational products can be ordered via the SAF on Ozone and Atmospheric Chemistry Monitoring site

Deutsches Zentrum für Luft- und Raumfahrt (DLR) provides near-real-time and historical maps of GOME-2 total column (ozone, nitrogen dioxide, tropospheric nitrogen dioxide, bromine oxide, sulphur dioxide, H2O, HCHO) and cloud products.

GOME-2 Summary Budgets
  Technical specifications
Spectral band (nm) 240–790
Spectral resolution (nm) 0.2–0.4
Spatial resolution (km2) 80 x 40 (main channels) 80 x 10 (PMD)
Earth coverage (km) 120–1920
Spectral channels 4096
Polarization channels 30
Calibration system Spectral lamp, white lamp, solar diffuser
Dimensions 600 mm x 800 mm x 500 mm
Weight 68 kg
Main bus voltage 22–37 V
Lifetime Five years
Power 50 W
Data rate interface 400 kbit