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Status of the operational IASI L2 version 5 products

Status of the operational IASI L2 version 5 products. Thomas August (EUMETSAT) Tim Hultberg, Dorothée Coppens, Arlindo Arriaga, Lars Fiedler, Xavier Calbet, Dieter Klaes, Peter Schlüssel, Rose Munro, Marc Crapeau. Outline. Overview of the IASI mission The IASI L2 processor (PPF) version 5

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Status of the operational IASI L2 version 5 products

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  1. Status of the operationalIASI L2 version 5 products Thomas August (EUMETSAT) Tim Hultberg, Dorothée Coppens, Arlindo Arriaga, Lars Fiedler, Xavier Calbet, Dieter Klaes, Peter Schlüssel, Rose Munro, Marc Crapeau

  2. Outline • Overview of the IASI mission • The IASI L2 processor (PPF) version 5 • Discussion on T, q validation • Summary

  3. I. The IASI mission The instrument Infrared Fourier transform interferometer Spectral range: 645 to 2760 cm-1 (15.5-3.62 µm) Spectral sampling: 0.25 cm-1 Footprint: 12 km (Nadir) Swath: ±1000km (± 48.3°) Surface Clouds Surface Clouds N2O CO2 CO CO2 O3 CH4 H2O T profiles

  4. I. The IASI mission Metop and the EPS program • European contribution to The Initial Joint Polar-orbiting System (IJPS) • Satellites in complementary orbits designed to ensure global data coverage at intervals of no more than 6 hours. • Prime objective: provide continuous, long-term data sets in support of operational meteorological and environmental forecasting and global climate monitoring. • Lifetime: 3 satellites, more than 14 years operation from October 2006. • Imager (AVHRR) and MW (AMSU,MHS) companions

  5. I. The IASI mission The operational L2 products Disseminated in NRT (sensing +3h) Vertical profiles: Temperature Vertical profiles: Humidity Land & Sea Surface Temperature TWT EMS Surface emissivity CLD Cloud detection and characterisation OZO Ozone: total & partial (0-6, 0-12, 0-16 km) columns CO N2O CH4 CO2 Total columns TRG Slide: 5

  6. II. IASI L2 PPF version 5 Why upgrade ? IASI – ECMWF @ 500 hPa 2 rmse Processing chain version 5 operational since 14 September 2010 ! v4 σ 1 σ bias Error [K] v5 0 -1 bias

  7. II. IASI L2 PPF version 5 The main steps • Input data pre-processing • Cloud detection and characterisation • Statistical retrievals: T, q, Ts, ε, trace gases • Optimal Estimation Method (OEM): T, q, Ts, O3 IASI L1C EOF ANN cloud-free OEM IASI L2 product NWP Aux. meas. EOFcloudy Conf. data Static db

  8. II. IASI L2 PPF version 5 The staticdatabases

  9. II. IASI L2 PPF version 5 Measurements & aux. products Raw L1C Ammonia Reconstructed • IASI L1C radiances • Noise-filtering via PC reconstruction • ECMWF 6h-forecasts: 00, 06, 12, 18 UTC • Up to 3h difference with sensing-time • Time-interpolation • AVHRR • L1B used if IASI L1C format < 11.0 • Cloud-fraction embedded in IASI 1C used for cloud screening • AMSU & MHS 1B • Not used yet. “Potential for the use of reconstructed IASI radiances in the detection of atmospheric trace gases”, N. C. Atkinson, F. I. Hilton, S. M. Illingworth, J. R. Eyre, and T. Hultberg, AMT 2010

  10. II. IASI L2 PPF version 5 Cloud detection Opt. depth test AVHRR test NWP test • NWP cloud test • OBS–CALC(NWP, ems, … ) @ chans 751 & 1023 • Cloudy if |OBS-CALC| > 1K • Relies on accurate forecasts and surface ems • AVHRR integrated cloud-fraction • IASI PSF weighted count of AVHRR cloudy pixels • Cloudy if CFR > 2% • Cloud optical depth test • EOF retrieval, D. Zhou et al., GRL 2005 • Triggers final acceptance of cloudy retrievals 18/11/2009 White: clear

  11. II. IASI L2 PPF version 5 Statisticalretrievals: T, q profiles • EOF retrieval (D. Zhou et al., 2005, GRL) • Regression with different coefficients for different viewing angles • Full profiles available under clear and partly cloudy conditions • Clear sky: first-guess in the final iterative retrieval • Clear sky: q profiles enters final L2 products • Cloudy IFOVs: after users request, the cloudy T,q profiles retrievals were added to the final IASI L2 products. Distributed since 02/12/2010.

  12. II. IASI L2 PPF version 5 Statisticalretrievals: SST Impact of the cloud & aerosol detection on the product quality AVHRR cloud test ANN cloud test No dust - ANN cloud test NWP cloud test Global figures Cold bias: 0.4 K σ ~ 0.4 K Outside aerosol areas Cold bias: 0.25 K σ < 0.3 K IASI L2P GHRSST (AATSR – IASI) SST

  13. II. IASI L2 PPF version 5 Statisticalretrievals: LST • 19-24 March 2010 :: Night • LANDSAF_MSG – IASI 10 K -10 Global figures (excluding deserts) ρ ~ 0.99 Warm bias ~ 1 K σ < 2 K Bias 0 5 K σ Slide: 13

  14. II. IASI L2 PPF version 5 The iterativeretrieval: OEM • Standard Optimal Estimation Method (OEM) after Rodgers: • J = (x - xa)T . B-1 . (x - xa) + (F(x) – y)T . R-1 . (F(x) – y) • Marquardt-Levenberg minimisation (5 iterations max.) • Active parameters: Tskin and T, q & O3 profiles • Background term computed in the EOF space of the atmospheric parameters: T -> 28 PCs, q -> 18 PCs, O3 -> 9 PCs • One unique global a priori and covariance matrix • 316 channels after Collard (Collard et al., QJRMS 2007) • global radiance tuning and measurement error covariance matrix: prior clear sky OBS-CALC • Forward model: RTIASI-4 optimised for faster computations • First guess: statistical retrievals

  15. II. IASI L2 PPF version 5 T, q profiles: non-regression check • Non-regression check and validation result from comparisons against ECMWF analyses. • 3 datasets: • “One Year” orbits centred on analyses synoptic times • “Focus days” (8 Sep 2007, 5 March and 9 May 2008) • 19-24 March 2010, with latest L1c products • Detailed results presented in EUM/MET/TEN/09/0448

  16. II. IASI L2 PPF version 5 T, q profiles: non-regression check Ps < 900 hPa

  17. II. IASI L2 PPF version 5 Temp. profiles: non-regression check • 19-24 March 2010 • IASI - ECMWF • Yield increased x1.7 • rms ≤ 1K [200-800hPa] rms ~ 0.7 K !!! rms ~ 0.7 K !!! - v5 - v4

  18. II. IASI L2 PPF version 5 WV profiles: non-regression check • 19-24 March 2010 • (IASI - ECMWF) • Bias reduced in BDL EOF FG OEM - v5 - v4

  19. II. IASI L2 PPF version 5 OEM: Future developements • Includecovariance Tskin – T – WV and possiblyO3in BG • Synergistic use of MW measurements: AMSU, MHS • Addphysicalconstraints(super-saturation and adabiatic lapse rate) to restrict solution space • More channelsneeded for humidityretrievals: externalstudy for MTG-IRS by C. Serio (Univ. Basilicata), paper by Rodgers in Adv. SpaceRes. 1998 • Migration to RTTOV-10: • Upgradedspectroscopy • MW instruments => residualcloud contamination effect • PCRTM => use more channels in retrievals • Simulation of clouds & aerosols All channels 300 channels 300 PCs Credits: C.Serio (Univ. Basilicata)

  20. III. Discussion on T,q validation T @ NOAA/NPROVS T @ 500 hPa T @ 700 hPa T @ 850 hPa IASI L2 PPFv5.0 PPFv4 PPFv5 IASI EUM IASI NOAA COSMIC UCAR AIRS AQUA http://www.star.nesdis.noaa.gov/smcd/opdb/poes/NPROVS.php Credits: NOAA / NESDIS Center for Satellite Applications and Research.

  21. III. Discussion on T,q validation WV @ NOAA/NPROVS WV @ 500 hPa WV @ 700 hPa WV @ 850 hPa PPFv5 IASI EUM IASI NOAA COSMIC UCAR AIRS AQUA Credits: NOAA / NESDIS Center for Satellite Applications and Research.

  22. III. Discussion on T,q validation Sondes @ Sodankylä • Humidity profiles: High variability, model vs sondes differences • Credits: X. Calbet (EUM) and R. Kivi (FMI) 13/07/2007 3σ noise Calbet et al., AMTD 2010

  23. III. Discussion on T,q validation ConcordIasi • Co-operation with F. Rabier and L. Lavanant (Meteo-France) • 3 main field experiments during Austral springs 2008, 2009 and 2010 • In 2010, 19 super-pressure balloons (CNES) launched from McMurdo, 6 with a scientific payload sounding the stratosphere, and 13 of the driftsonde type developed at NCAR. • From the 13 driftsondes flying at around 20km altitude, ~640 dropsondes were dropped over Antarctica and the surrounding seas, coincident with Metop overpasses. • Additional measurements performed at other stations in Antarctica: Dumont d’Urville, Concordia and Rothera. • Drop-ondes coincident with Metop and A-Train overpasses IASI/AVHRR CTP @ CMF IASI CTP @ EUM Credits: Lydie Lavanant CALIOP CTP (hPa)

  24. Summary • PPFv5 operational since 14/09/2010 ! • Significant improvements: T, LST, clouds (O3, CO) • Products further characterised: SST, LST • Some cloudy retrievals • Validation documentation available on-line: www.eumetsat.int • Improve/characterise further T and q in bottom layers • Reduce use of NWP forecasts • Seasonal variations in long-term monitoring: origins ? How to account for it in CDRs ? • clouds/aerosol detection/simulation impact on WV profiles quality ? • What WV products references for the validation of satellite retrieved profiles with ground resolution of 12-30 km ?

  25. Thank you for your attention ! • thomas.august@eumetsat.int

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