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| Titel |
Comparison between IASI and GOSAT retrievals in the thermal infrared |
| VerfasserIn |
S. Payan, C. Camy-Peyret, J. Bureau, K. Shiomi |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066345
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| Zusammenfassung |
| GOSAT (Greenhouse Gases Observing SATellite) is a satellite dedicated to the
study of greenhouses gases. It carries an infrared Fourier transform spectrometer
(The Thermal and Near Infrared Sensor for Carbon Observation Fourier-Transform
Spectrometer or TANSO-FTS), which acquires spectra in 4 bands, located in the
Near-Infrared (NIR), ShortWave Infrared (SWIR) and Thermal Infrared (TIR). An
imager (CAI: Cloud and Aerosols imager) enables to gain information on clouds
and aerosols, and this information is used to improve the quality of CO2 and CH4
retrievals.
IASI (Infrared Atmospheric Sounding Interferometer) designed by CNES for Eumetsat
is carried by the MetOp-A satellite. It is used for operational meteorology and is
also interesting for greenhouse gases as well as for atmospheric chemistry and
climate.
We looked for close spatial and temporal coincidences between IASI and TANSO-FTS
nadir spectra. Due to the respective orbits of MetOp-A and GOSAT, this is only achieved at
high latitudes. We compared the surface temperature, CO2, CH4, N2O and O3 mixing ratios
retrieved from TANSO-FTS and from IASI spectra. We used the [940;980] cm-1 window for
CO2 (laser band), [1240;1320] cm-1 for CH4, [1140;1200] cm-1 for N2O, and [980;1100]
cm-1 for O3. Since IASI is considered as a reference for radiometric calibrations, we
compared the surface temperatures retrieved by GOSAT and IASI in these different windows
to assess the GOSAT radiometric calibration. The GOSAT/IASI comparison is
done on surface temperature rather than on raw radiances because the different
instrumental noise and spectral resolution of these instruments make a direct comparison
of the radiances more difficult. The use of different spectral windows enabled us
to explore the spectral dependence of the TANSO-FTS radiometric calibration.
Cloud-free and spatially homogenous fields of view (IFOVs) were selected using CAI
images.
Finally, we will show the potential to further improve the results using the synergy
between measurements in the TIR and the SWIR spectral domains. |
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