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The French operational radar network

THE NEW FRENCH OPERATIONAL CONVENTIONAL RADAR PRODUCTS Pierre Tabary Centre de Météorologie Radar, Direction des Systèmes d’Observation, Météo France pierre.tabary@meteo.fr. The French operational radar network.

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The French operational radar network

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  1. THE NEW FRENCH OPERATIONAL CONVENTIONAL RADAR PRODUCTSPierre TabaryCentre de Météorologie Radar, Direction des Systèmes d’Observation, Météo Francepierre.tabary@meteo.fr

  2. The French operational radar network • In 2006 : 24 radars of different wavelength (8 S-band, 16 C-band) and type (GEMATRONIK, THOMSON, …) • All radars are equipped with the same « home-made » radar processor (CASTOR2, See the contribution of Parent-du-Châtelet et al. to the 2001 Radar Conference) • Doppler processing (« staggered-PRT », See Tabary et al., 2005, JAOT) and products are gradually introduced  all radars will be Doppler by 2008; • Polarimetry is currently tested on the Trappes (Paris) radar (See Poster 4.13 by Gourley et al.)  8 polarimetric radars by the end of 2006 ?

  3. Current operational products Rainfall intensity maps ( Surveillance, Nowcasting, Aviation safety, …) • 1 km² x 5 minutes; • Constant pseudo-CAPPI composition; • Dynamical ground-clutter suppression; • No VPR nor partial beam-blocking correction; • Marshall-Palmer Z-R relationship; Single radar (Bollène) Composite (France) 9 September 2002 09.00 UTC • Radar QPE ( Hydrology) • Single radar only; • Available every 15 minutes; • No radar – rain gauge real-time adjustment; 24h accumulation – Toulouse radar – Start = 16 April 2005 06.00 UTC

  4. The new conventional radar products Radar QPE  Hydrology • Pixel-by-pixel composition (Joss and Lee 1995); • VPR correction (Kitchen et al. 1994, Andrieu et al. 1995) • Partial beam blocking correction (orogenic : Delrieu et al. 1995 and non-orogenic : use of long-term accumulations); • Enhanced frequency : 5 minutes ( Urban applications); • Systematic generation of quantitative quality indexes; Single radar Composite Single radar Radar « Detection product »  Nowcasting • Maximum reflectivity along the vertical; • Bright-band correction only; • Partial beam blocking correction ; • Systematic generation of detailled quality indexes; Composite

  5. RR1corr 1 RR2corr 2 RR3corr 3 Courtesy of JJ Gourley (NSSL) RR2 unshielded, not too high, but in the bright band RR3 Unshielded, not in the bright-band, but high 3 The new radar QPE 2 1 ? RR1 low but shielded Correction for VPR, partial beam-blocking, ground-clutter and advection RR1 RR2 RR3 Try to get the best surface estimation from the ith tilt Assign a weight to each estimation RRbest = iiRRicorr / ii best=MAXi(i) Weighted linear combination

  6. The VPR correction Kitchen et al. 1994; Kitchen 1996; Andrieu et al. 1995, Fabry and Zawadzki 1995 Simulate VPR candidates The four parameters can only take a limited number of predetermined, climatology-based values A conceptual four-parameter VPR 3dB beamwidth Simulate – for each VPR candidate - the expected radar observations (ratio curves) Optimal VPR A guess is provided by the model Observed radar measurements (ratio curves) Correction / extrapolation down to ground-level

  7. Comparison of radar-derived Freezing Level Heights with radiosonde 0°C (dry and wet bulb) heights

  8. Illustration of Single-radar QPE 24 h accumulation – 20050206 - Opoul radar Old QPE (HYDRAM) New QPE (PANTHERE) Quality indexes 0 (purple) = excellent 255 (red)= bad Proposed (empirical) formula for the quality index:  = exp[-(h-hterrain) / h0] x (1-T/100)1/1.6 0 if ground-clutter or strongly shielded (T > 70%) with : h = altitude of the beam, h0 = 1 km and T = occultation rate (%)

  9. Are the proposed quality indexes relevant ? Is there a correlation between radar vs. rain gauge scores and the quality indexes ? Nash criterion Corr. coefficient 0 (good) Quality indexes 200 (bad) 0 (good) Quality indexes 200 (bad) 15 episodes included. Each curve corresponds to one episode. The dotted curve is the mean

  10. Illustration of composite QPE 24 h accumulation – 20050206 – 7 radars of Southern France Composite quality index map Applications Composite QPE • NWP QPF verification; • Radar – rain gauge adjustment; • Assimilation in hydrologic models; Rcomposite = jradar Rjradar / jradar composite = MAXjradar(jradar)

  11. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  12. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  13. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  14. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  15. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  16. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  17. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  18. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  19. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  20. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  21. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  22. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  23. The Single-radar and composite « detection product » Attenuation by rain Partial beam blocking Maximum reflectivity 3-level quality index Altitude Bright band correction Advection duration Status of the pixel

  24. Thank you

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