REGIONAL INSTRUMENT CENTRE: REVIEW AND STRENGTHENING Dr Jérôme DUVERNOY [email protected].
THE NEW FRENCH OPERATIONAL CONVENTIONAL RADAR PRODUCTS Pierre Tabary Centre de Météorologie Radar,...
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Transcript of THE NEW FRENCH OPERATIONAL CONVENTIONAL RADAR PRODUCTS Pierre Tabary Centre de Météorologie Radar,...
THE NEW FRENCH OPERATIONAL CONVENTIONAL RADAR PRODUCTS
Pierre TabaryCentre de Météorologie Radar, Direction des Systèmes d’Observation, Météo France
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 ?
Current operational productsRainfall intensity maps ( Surveillance, Nowcasting, Aviation safety, …)
Single radar (Bollène) Composite (France)
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;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
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
Radar « Detection product » Nowcasting
Maximum reflectivity along the vertical;
Bright-band correction only;
Partial beam blocking correction ;
Systematic generation of detailled quality indexes;
Single radar
Composite
?
RR3
Unshielded, not in the bright-band, but high
RR2
unshielded, not too high, but in the bright band
RR1
low but shielded
1
2
3
Courtesy of JJ Gourley (NSSL)
RR1 RR2 RR3
RR1corr
1
RR2corr
2
RR3corr
3
Correction for VPR, partial beam-blocking, ground-clutter and advection
RRbest = iiRRicorr / ii
best=MAXi(i)Weighted linear combination
The new radar QPE
Try to get the best surface estimation from the ith tilt
Assign a weight to each estimation
The VPR correctionKitchen et al. 1994; Kitchen 1996; Andrieu et al. 1995, Fabry and Zawadzki 1995
Simulate – for each VPR candidate - the expected radar observations (ratio
curves)
Simulate VPR candidates
The four parameters can only take a limited number
of predetermined, climatology-based values
Observed radar measurements (ratio
curves)
Optimal VPR
Correction / extrapolation down to ground-level
A conceptual four-parameter VPR
3dB beamwidth
A guess is provided by the model
Comparison of radar-derived Freezing Level Heights with radiosonde 0°C (dry and wet bulb) heights
Illustration of Single-radar QPE24 h accumulation – 20050206 - Opoul radar
Old QPE (HYDRAM) New QPE (PANTHERE) Quality indexes
0 (purple) = excellent
255 (red)= badProposed (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 (%)
Are the proposed quality indexes relevant ?Is there a correlation between radar vs. rain gauge scores and the quality indexes ?
15 episodes included. Each curve corresponds to one episode. The dotted curve is the mean
Nash criterion
Corr. coefficient
0 (good) Quality indexes 200 (bad) 0 (good) Quality indexes 200 (bad)
Illustration of composite QPE24 h accumulation – 20050206 – 7 radars of Southern France
Composite QPE
Composite quality index map
Rcomposite = jradar Rjradar / jradar
composite = MAXjradar(jradar)
Applications
NWP QPF verification;
Radar – rain gauge adjustment;
Assimilation in hydrologic models;
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
The Single-radar and composite « detection product »
Attenuation by rain Partial beam blocking
Altitude
Status of the pixelBright band correction
3-level quality index
Advection duration
Maximum reflectivity
Thank you