Comparison of IASI-A and IASI-B L1C data on the MetOp satellites: monitoring of radiometric and spectral performances and possible use for climate studies

Abstract : A method is presented to compare the L1c products (calibrated radiance spectra) of the two IASI (In- frared Atmospheric Sounding Interferometer) instruments on board the two Metop satellites Metop-A and Metop-B. After defining categories of homogenous geophysical/geographical conditions (day/night, ocean/night, clear/overcast), one can produce grand average spectra with the corresponding statistical diagnostics on the L1c spectral grid (8461 channels between 645 and 2760 cm-1 with a spacing of 0.250 cm-1 ). The corresponding spectra are generated monthly for the 30 scan positions (SP) of the scene acquisition mirror and for the 4 pixels (PN or IFOV) of the two IR sounders. These average spectra (with a much reduced noise as compared to one individual IASI spectrum) and the corresponding uncertainty on a channel-by-channel basis (with a Gaussian character check) can then be used to compare the two instruments on the short time scale (month or shorter periods). A pixel-by-pixel comparison of IASI-A and IASI-B is not possible because the two instruments can never "see" the same footprint at the same time, since they are flying 50 min apart on the same orbit. But due to this small time difference, the set of sampled IFOVs used for generating the averages (over given homogeneous categories) should obey the approximation ≅ - . The left term of the equation would be the hypothetical pixel-by-pixel spectral radiance difference of the two sounders if they were sampling the same footprint at the same time. The right hand side term is the difference calculated from the mean of the individual sounders calculated for the various categories over a given time period. A status on the efforts to implement this tool in the EPS monitoring environment and the potential for instrument as well as climate monitoring is presented.
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https://hal.archives-ouvertes.fr/hal-00993380
Contributor : Jérôme Bureau <>
Submitted on : Tuesday, May 20, 2014 - 11:05:07 AM
Last modification on : Thursday, July 25, 2019 - 4:34:10 PM

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  • HAL Id : hal-00993380, version 1

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Claude Camy-Peyret, Jérôme Bureau, Dorothée Coppens, Bertrand Théodore, T. August. Comparison of IASI-A and IASI-B L1C data on the MetOp satellites: monitoring of radiometric and spectral performances and possible use for climate studies. 2013 EUMETSAT Meteorological Satellite Conference -19th American Meteorological Society (AMS) Satellite Meteorology, Oceanography and Climatology Conference, Sep 2013, Vienne, Austria. pp.Session 8 - Instrument calibration and characterisation. ⟨hal-00993380⟩

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