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IASI InIASI In--OrbitOrbit ExperienceExperienceCLARREO workshop, University of Maryland,

17-19 July 2007

Claude Camy-PeyretLaboratoire de Physique Moléculaire pour l’Atmosphère et

l’Astrophysique (LPMAA), UMR 1043 CNRS/UPMCUPMC, 4, place Jussieu, case 76, 75252 Paris Cedex 05Immeuble « Le Raphaël », 3 rue Galilée, Ivry-sur-Seine

camy@ccr.jussieu.fr

CLARREO workshop, University of Maryland, 17-19 July 2007

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Presentation given in the name of many people and agencies involved in

IASI (Infrared Atmospheric Sounding Interferometer)

This presenter (co-chairman with J. Taylor of the IASI Sounding Science Working Group or ISSWG) is a « speaker » for all of them. In particularDenis Blumstein from CNES, responsible for the IASI L1 Cal/Val team provided plates presented during the 2nd Meeting of GSICS Research

Working Group at EUMETSAT, Darmstadt, Germany on 12-14 June 2007

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TEC = Technical Expertise Center at CNES in Toulouse

TEC is preparing tables of instrument parameters to be uploaded to the IASI instrument by the core EPS ground segment as needed

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Overview of the instrument

– Normal Operation (N. Op) mode : 30 ground footprints (4 pixels each) every cycle (8 sec)2 features of the instrument will be used intensively for Cal/Val activities– External Calibration (E. Cal) mode Viewing dir. (i.e. Scan Position : SP) remains fixed

• On-board radiometric calibration is performed as in Normal Operation mode• Fixed position can be changed at each cycle : SP=1..30 (30 Earth Views or EV),

BB, CS1, CS2 or SM (Scan Mirror)– Verification Data Selection (in N. OP mode and in E. Cal mode)

• 1 raw interferogram (over 408) is available in scientific telemetry every 8 sec• Pixel Number, Step Number and Spectral Band (PN, SN, SB) which define this interferogram can be

modified every 8 sec (periodic pattern modified by TC)

CLARREO workshop, University of Maryland, 17-19 July 2007

OPDmax = 2 cm, level 1c 0.5cm-1 resolution, 0.25 cm-1 sampling

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IASI spatial sampling

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Schlüssel and Hultberg, 2007

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spatially uniform pixels

all pixels, radiances shiftedby 0.02 mW m-2 sr-1 /cm-1

curves for pixels P1, P2, P3 and P4as a function of scan position (SP)

correlation for pixel P1

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CS1

CS2

Difference beween CS1 and CS2 ~0.2 % of B(285 K) explained by difference of angles on the scan mirror. Well explained by instrument model.

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TOP = Table of On-board Parameters

CS2

CS1

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C = compliantW = waiver

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CLARREO in the context of other international efforts

MetOp of EUMETSAT with a series of 3 satellites (5 yr lifetimeeach) will provide precise/accurate climate related data over a

span of 15 years (start end of 2006)IASI for the IR

GOME-2 for the SW

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IASI Level 1 IR radiances

• In-orbit internal radiometric calibration essential (BB temperature relatedto NIST standards by industry, BB emissivity determined on ground pre-flight, constant monitoring of instrument parameters at TEC)• Overlap periods expected between « identical » IASI instrument modelson 3 successive MetOp satellites• Careful inter-comparisons between different IR satellite sensors (IASI, AVHRR, AIRS up to now, TES … in a later phase) proved very efficient to validate radiometric performances• Importance of synergy between IR sounder (IASI) and imagers (IIS and AVHRR) for proper scene heterogeneity characterization (surface and clouds)

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First IASI conference

Organized by CNES and EUMETSAT in Anglet (near Biarritz), France from 13 to 16 November 2007

http://smsc.cnes.fr/IASI

CLARREO workshop, University of Maryland, 17-19 July 2007