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Go to ‚View‘ menu and click on ‚Slide Master‘ to update this footer. Include DM reference, version number and date1 THE MTG-IRS MISSION Stephen Tjemkes, Stefano Gigli, Gary Fowler, Rolf Stuhlmann EUMETSAT
2NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 Overview The MTG-IRS Mission The MTG-IRS Instrument, design and main performance The MTG-IRS Level 1B data L2 Processing Data volume and dissemination
3NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Mission The Post-MSG user consultation process identified the following user needs: Information on vertical structure of moisture, temperature and wind at high spatial and temporal resolution, support to emerging operational air-chemistry and air-quality applications.
4NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: high level requirements Analysis of these needs by remote sensing experts resulted observational requirements: Sampling at moderate high spectral, Sampling of a full disc within 60 minutes, Sampling at high spatial resolution.
5NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: Characteristics These requirements resulted in the design of MTG-IRS instrument: Mounted on MTG-S platform Observations in two broad bands MWIR: 1600 – 2175 cm -1 LWIR: 700 – 1210 cm -1 at moderate spectral resolution (0.625 cm -1 ) Two large detector arrays 160x160 detectors Spatial sampling 4 km at SSP covering region of approximately 600 x 600 km 2 Observations in step and stare. Sampling of one stare: 10 sec. Approximately 300 stares to cover GEO Disc
6NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 Front Telescope Scan MirrorBaffle Interferometer BackTelescope Cooled Focusing Optics Cooled Matrix Detectors Blackbody OPTICS The MTG-IRS Instrument: Sketch IRS design: OHB – Munich Source: MTG-KT-IR-DD-0004 Volume: 1.4 x 1.6 x 2.2 m 3 Mass: 400 kg Power: 750 W
7NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: Working Principle The instrument works in step-&-stare mode, with the Earth disc covered through a sequence of contiguous square sub-images (dwells). With the current design, each dwell is taken in 10s and covers about 640 x 640 km 2 (at nadir) with 160 x 160 spatial samples. Within a single dwell, a set of interferograms, one per spatial sample, is produced. A spectral sounding is the result of the Fourier transformation of an interferogram from a single spatial sample L1 processing L0 Spectral sounding Interferogram Earth Dwell Spatia l sampl e time L1 wavenumber
8NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: Spatial Coverage & Repeat Cycle The Earth disc is split in 4 Local Area Coverage (LAC) Zones Each LAC has about 80 dwells Numbered from South to North Sampling: It takes 15 min to sample a LAC. LAC4 is revisited every 30 min In 6 hours (BRC): 12xLAC4, 5xLAC3, 4xLAC2, 3xLAC1 LAC 1 LAC 2 LAC 3 LAC 4
9NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: Radiometric Calibration To generate radiometric and spectral accurate level 1b data for the users a number of corrections to the raw observations have to be applied. The temperature variations inside the instrument generate the need for a continuative radiometric calibration; this is achieved by regularly looking at Deep Space (DS) views and at an internal calibrated blackbody (BB view) The Sun (when near the FOV) and the Earth itself (at any time) produce straylight, that spoils the radiometric accuracy. Straylight correction algorithms will be introduced in the L1 processing
10NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: Timeliness Objective is to make the observations available as soon as it makes physical sense (calibrated and navigated). According to current status of development this implies that release of observations is limited by availability of auxiliary information needed to perform radiometric calibration. Currently an interpolation between the two DS views at beginning and end of scan line is needed to give the best performance possible. Level 1 Processing of a raw observation can only start after completion of full scan line: 3 min at equator (worse case). However, a trade with an extrapolation method to remove the dependency of the second DS view is needed. Release of the level 1 data depends further on performance of level 1 processor which is currently TBD. DS2
11NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: Spectral Calibration Need for spectral calibration: Large detector arrays introduce effects which result in a spectral shift of the observations collected by detector at centre or at the edge of array Thermo-mechanical instabilities produce misalignments of the interferometric axis, which induces additional spectral shifts Instabilities of the metrology laser introduces inaccuracies in spectral axis Scope of the spectral calibration is determining a spectral scaling shift factor, to be used for correctly rescaling the spectra of the observed Earth views to a common reference spectral axis for all detectors
12NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: Spectral Calibration No spectral calibration device is present inside the instrument; the calibration is achieved looking at suitably selected Earth scenes with known and stable spectral behaviour To this aim a number of dwells in an area over the North Atlantic Ocean has been selected for two main reasons: They belong to LAC4, hence they are revisited more often (every 30 min) They ensure stable and well known conditions, thanks to the fact that the entire observed surface is sea
13NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Instrument: L1B Products 1.Level 1b data are the radiometric and spectral calibrated observations with geolocation information appended. The level 1b data will not be rectified to a reference grid. 2. Plan to store radiances in the 1B product as 16-bit Integer value with fixed scaling factors (8-bit ) per channel. Estimates show the dynamic radiance range in a channel can be accommodated without information loss. 3.Level 1B will be generated in netCDF format complying to the MTG Generic Format Specification (GFS). 4.Estimated Volume Level 1B data full spectrum: 1.9.01 Gbyte per LAC 2.865 Gbyte per 24 h (48xLAC4, 20xLAC3, 16xLAC2, 12xLAC1). 5.Level 1B data is disseminated as a Principal Components compressed dataset to reduce datavolume: 1.1.35 Gbyte per LAC 2.139 Gbyte per 24 h (48xLAC4, 20xLAC3, 16xLAC2, 12xLAC1). 6.No cloud information is provided with the Level 1B data.
14NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Level 2 Processor: Overview To generate Moisture, temperature profiles from MTG-IRS a level 2 processor is foreseen. Processor is a basic 1DVAR using ECMWF short term forecast as background (both state and error covariance matrix)
15NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Level 2 Processor: Planned Products Product TypeParameter Description Temperature ProfilePrior and Posterior temperature profiles with standard deviation Specific Humidity Profile Prior and Posterior humidity profiles with standard deviation Ozone ProfileArchive. Prior and Posterior ozone profiles with standard deviation Surface State ProductSurface parameters: Temperature, pressure and emissivity Scale Projected StateFor data assimilation of L2 products by regional scale NWP based on only the temperature and specific humidity profiles. Archive flavour additionally contains Eigen values and vectors. Meta dataNavigation information, ancillary parameters, processing and quality flags and exit statuses.
16NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS Level 2 Products dissemination Products will be generated in netCDF format complying to the MTG Generic Format Specification (GFS). Level 2 products only disseminated for clear sky regions within LAC-4
17NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS MAG and User Readiness To support the MTG-IRS development a MTG-IRS Mission Advisory Group (MAG) has been formed. Key element is to give guidance to Secretariat on issues of L1 and L2 products and processing and support the CAL/VAL. MAG link to NWCSAF: M. Martinez (AEMET)
18NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 The MTG-IRS MAG and User Readiness Some user readiness activities have been started also to support definition of L2 products. This is done with IASI as MTG-proxy and the Level 2 Validation and Demonstration Processor (L2VDP).
19NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 MTG-IRS L2VDP Supports the detailed definition of the operational processor, End-to-end Processor Pre Processing: Scene classification: based on information contained is spectrum. Product generation:1DVAR T(p), q(p), O3(p), Emissivity, surface temperature Based on UWPHYSRET/Mirto used for CrIS/IASI at Univ. of Hawaii with direct readout Post Processing: Scaled Projected State
20NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 19.01.10 Results 29 July 2012, 18UTC LAPS orgLAPS L2VDP TT-index values: > 50 moderate-severe thunderstorms > 60 severe thunderstorms Time UTC 18 UTC E. Gregow: FMI Analysis of TT index with and without L2 products by LAPS 20
21NWC-SAF 215 Users‘ Workshop: ref: EUM/MTG/VWG/15/793016 Location of the single level 2 profile: Altenstadt, Germany