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REDOSAT-RUN RE- Analysing D ata O f SAT ellite imagery RSMC La R é UN ion

This project aims to improve and homogenize the Best-Track database of Tropical Cyclones in the South Indian Ocean by re-analyzing the all-stages Tropical systems using HURSAT Satellite Pictures database from 1978-2006. Tools have been developed for data conversion, visualization, and analysis.

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REDOSAT-RUN RE- Analysing D ata O f SAT ellite imagery RSMC La R é UN ion

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  1. REDOSAT-RUNRE-Analysing Data Of SATelliteimageryRSMC La RéUNion 2nd International Best Tracks Archive for DataStewardship (IBTrACS) Workshop Honolulu 11-13 April 2011 Thierry Dupont - RSMC La Réunion - Mars 2011

  2. Plan • Context • Objectives of our re-analysis project over the South Indian Ocean • What we really had in real-time before Hursat ? • What we have now ? • What we needed to start this re-analysis project? • Downloading and dealing with the Hursat data • Exemple of in-house built layers • Methodology 1st Step : To a purely « Dvorak based » Best-Track • Methodology 2nd Step : To a « final » Best-Track • Planning of the project.

  3. Context • 6th International Workshop on Tropical Cyclones (IWTC-VI) (Costa-Rica 2006) To study Tropical Cyclone activity and its eventual modifications in relationship with the global warming, it's primordial to work with "clean", high quality and "homogeneous"  Tropical Cyclone databases. • Long-standing internal knowledge of the deficiencies of our cyclone database.

  4. Objectives of our project over the South Indian Ocean • Using the Hursat Satellite Pictures database (1978-2006), the goal is to re-analyse the all-stages Tropical systems over the South Indian Ocean to improve and homogenize our Best-Track database. • Re-analysis is focusing primarily on the pre-geostationary era, i.e. before May 1998. • This re-analysis will be conducted backwards in time from 1997/1998 to 1978/1979 TC seasons. Knapp and Kossin (2007)

  5. What we really had in real-time before Hursat ? Plenty satellite pictures were not available at La Reunion's Tropical Cyclone Centre in the past (DMSP, NOAA orbits outside of our scope of acquisition) or have been more or less poorly exploited (Dvorak not used or inappropriately used ... no digital but « manually gridded » hardcopy printouts pictures).

  6. What we have now ? • NCDC : National Climatic Data Center  (Asheville) • Digital Satellite Pictures focussed on Tropical Disturbances (HURricane SATellite). • Easy to get on available ftp server. • Standart format (NETCDF) • Calibrated without temporal bias (fixed resolution over the re-analysis period) • HURSAT-B1 (International Satellite Cloud Climatology Project (ISCCP) B1  ) : • Geostationary satellites.. • IR, VIS, VW at 8km resolution every 3 hours • HURSAT-AVHRR : • Avhrr satellites • Channels IR, VIS, VW at 4km resolution every 12 hours or more.

  7. What we needed to start this re-analysis project ? Geo-referenced Satellite Pictures: • We had to develop tools to convert and produce different channels and palettes pictures from Hursat Netcdf files (tools based on Ferret and ImageMagik). Visualization and Navigation • We adapted our in-house operational software and workstation Synergie-Cyclone. Tools and Technics for analysis • Dvorak Technique is daily used by all TC Specialists and Senior Forecasters of the re-analysis team.. • Some NWP models fields are also extracted for environmental conditions/parameters.

  8. Downloading and dealing with the Hursat data • First step is to identify systems and to link the SWIO and IBTrACS Nomenclatures (not obvious). • netcdf files are downloaded from eclipse ftp server. ftp://eclipse.ncdc.noaa.gov/pub/hursat/ • netcdf files are locally converted (thanks to ferret macros) to layers which can be used by our in-house Synergie-Cyclone software. 1 Synergie-Cyclone Layer = 1 png pictures + 1 ascii georeferenced file.

  9. In-house built layers – Hursat-B1 (1) Visible Channel (VSCHN) 0.51 – 0.99 μm Colored Composite (VSCHN + IRWIN) Daniella Met-5 1996.12.08.0600 Daniella Met-5 1996.12.08.0600

  10. In-house built layers – Hursat-B1 (2) InfraRed Channel (IRWIN) 10.2 - 11.4 μm Water VaporInfraRed Channel (IRWVP) 6.7 – 7.2 μm Daniella Met-5 1996.12.08.0600 Daniella Met-5 1996.12.08.0600

  11. In-house built layers – Hursat-B1 (3) InfraRed Channel (IRWIN) 10.2 - 11.4 μm InfraRed Channel (IRWIN) 10.2 - 11.4 μm Daniella Met-5 1996.12.05.0600 Daniella Met-5 1996.12.08.0600 Brightness Temp from -55°C to -45°C Enhanced Colored Dvorak Palette

  12. In-house built layers – Hursat-AVHRR (1) Visible Reflectance (CH1_REF) 0.6 μm Visible Reflectance (CH3_REF) 1.6 μm Daniella Noaa-14 1996.12.08.1024 Daniella Noaa-12 1996.12.09.1438

  13. In-house built layers – Hursat-AVHRR (2) InfraRed Channel (CH4_TEMP) 11.0 μm NearInfraRed Channel (CH3_TEMP) 3.7 μm Daniella Noaa-14 1996.12.08.1024 Daniella Noaa-12 1996.12.09.1438

  14. In-house built layers – Hursat-AVHRR (3) DaytimeColored Composite Vis 0.6 μm + Vis 0.9 μm + IR 11.0 μm NighttimeColored Composite NIR 3.7 μm + IR 11.0 μm Daniella Noaa-14 1996.12.08.1024 Daniella Noaa-12 1996.12.09.1438

  15. In-house built layers – Hursat-AVHRR (4) InfraRed Channel (CH4_TEMP) 11.0 μm InfraRed Channel (CH4_TEMP) 11.0 μm Daniella Noaa-12 1996.12.06.0315 Daniella Noaa-12 1996.12.06.0315 Brightness Temp from -55°C to -45°C Enhanced Colored Dvorak Palette

  16. In-house built layers – Hursat-DMSP (1) DMSP layers are actually produced thanks to Google Earth kml files built by NCDC. We plan to produce them directly from netcdf files.

  17. Methodology 1st Step : To a purely "Dvorak based" Best-Track • Each system to analyse is affected to a group formed with 3 TC Specialists/Senior Forecasters (2 groups). • Each analyst performs "blind" and independent analyses (only with the Dvorak technique) (LatLon, confidence, T, CI, 10mn MaxWind, Gusts, Stormtype) and determines some empirical parameters, RMW, empirical extension of the gales). • When the 3 analysts end this first step, they meet together to build a synthetic and common purely "Dvorak based" BestTrack

  18. Methodology 2nd Step : To a "final" Best-Track • Then the group will adjust the "Dvorak" BT with other available data, like microwave imagery, ECMWF SLP re-analysis fields and all -generally sparse- available observations (we need to further investigate the ICOADS Ship database). • It results 2 BT • A purely "Dvorak based" BestTrack (for studies, comparison, homogeneous reference...) • A "climatological" one.

  19. Re-analysis – Daniella December 1996Only Dvorak Analysis 05/12/1996 at 1200Z Location : -14.19S /56.38E T = 6.5 T average over 6 h = 5.5 Met = 5.5 / PT = 6.0 FT = 5.5+ / Ci=5.5+ 10mn max Winds = 95kt Gusts = 135kt R35kt CDO estimate R35SW = 60 NM … RMW measured IR=-50°C RMW = 20 NM

  20. Re-analysis – Daniella December 1996 Other data adjustments 05/12/1996 at 1200Z RMW adjusted thanks to microwave imagery. RMW = 24 NM First closedIsobar : 1008 hPa Diameter : 510 NM MSLP computed thanks to Wind-Pressure Relationship Courtney &Knaff = 952 hPa.

  21. Re-analysis – Daniella December 1996Wind Radii Holland Adjustment Le 05/12/1996 à 1200Z – Wind Radii computed thanks to Holland Vortex (1980) forced by 34kt radii. Non-forced computed wind radii 34kt radii forced computed wind radii

  22. RedoSat-Run Planning of the project • May to October 2011 : Test of the re-analysis procedures and methodology with the TC season 1996/1997 (19 TCs over SWI + 7 TCs over SEI) • Then we plan to re-analyse 6 TC seasons each year, which means 3 seasons per group. • The whole  period 1978-1998 should be re-analysed in 3 to 4 years. Thierry Dupont - RSMC La Réunion - Mars 2011

  23. Thanks for your attentionMerci de votre attention Thierry Dupont - RSMC La Réunion - Mars 2011

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