M URS La solution aux murs de gypse… « Présentation Générale » .
Alessandro Hering 1 , Urs Germann 1 , Marco Boscacci 1 , Stéphane Sénési 2
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Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology MeteoSwiss Operational thunderstorm nowcasting in the Alpine region using 3D-radar severe weather parameters and lightning data Alessandro Hering 1 , Urs Germann 1 , Marco Boscacci 1 , Stéphane Sénési 2 1 MeteoSwiss, Locarno-Monti, Switzerland 2 Météo-France, Toulouse, France.
description
Operational thunderstorm nowcasting in the Alpine region using 3D-radar severe weather parameters and lightning data. Alessandro Hering 1 , Urs Germann 1 , Marco Boscacci 1 , Stéphane Sénési 2 1 MeteoSwiss, Locarno-Monti, Switzerland 2 Météo-France, Toulouse, France. - PowerPoint PPT Presentation
Transcript of Alessandro Hering 1 , Urs Germann 1 , Marco Boscacci 1 , Stéphane Sénési 2
Federal Department of Home Affairs FDHAFederal Office of Meteorology and Climatology MeteoSwiss
Operational thunderstorm nowcasting in the Alpine region using 3D-radar
severe weather parameters and lightning data
Alessandro Hering1, Urs Germann1, Marco Boscacci1, Stéphane Sénési2
1 MeteoSwiss, Locarno-Monti, Switzerland2 Météo-France, Toulouse, France.
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Montreux, Lake Geneva, 18.7.2005
Source: Webcam Hotel Splendid, Montreux, Switzerland
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Montreux, Lake Geneva, 18.7.2005
Source: Webcam Hotel Splendid, Montreux, Switzerland
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Montreux, Lake Geneva, 18.7.2005
Source: Webcam Hotel Splendid, Montreux, Switzerland
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TRT (Thunderstorms Radar Tracking)
TRT Cell tracking
Montreux (webcam)
TRT Cell-based VIL(Vertically Integrated Liquid)
18.7.2005 (12:50-14:35)
220
km
13dBZ 25dBZ 40dBZ 55dBZ
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TRT (Thunderstorms Radar Tracking)
TRT Cell tracking TRT Cell-based VIL(Vertically Integrated Liquid)
18.7.2005 (12:50-14:35)
220
km
13dBZ 25dBZ 40dBZ 55dBZ
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TRT (Thunderstorms Radar Tracking)
TRT Cell-based VIL(Vertically Integrated Liquid)
18.7.2005 (12:50-14:35)
TRT Cell tracking
220
km
13dBZ 25dBZ 40dBZ 55dBZ
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Scan geometry, Orography
• Scan geometry of Swiss radar La Dôle situated on a mountain top (1680 m a.s.l.) near Geneva
• Orography roughly in the direction of the hail swath on 18 July 2005
Montreux (webcam)
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TRT (Thunderstorms Radar Tracking)
• TRT: real-time object-oriented tool for thunderstorms nowcasting based on multiple-radar composites
• 2003: TRT operational at MeteoSwiss• Detection: Dynamic reflectivity thresholding scheme• cells detected at individual thresholds: 36-48 dBZ
• 2004: Improved cell position extrapolation
• 2005: Lightning data added → multiple-sensors system
• 2006: 3D multiple-radar derived storm properties
cell-based (time series), grid-based (2D horizontal fields):• VIL (Vertically Integrated Liquid)• EchoTops 15/45 dBZ• Max storm reflectivity altitude
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Operational view: cell-based attributes
VIL, 15/45 EchoTops, storm altitudes:
• Cartesian composite 3 C-band Doppler radars
• 20 elevation scan (-0.3° / 40°)
• 12 CAPPI between 1 and 12 km
• 5 min
Lightning data:• CG positive/negative
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The severe hailstorm on 18 July 2005
• One cell, 11:00-15:00 UTC, developed to a supercell hailstorm moving over Lake Geneva to western Switzerland
• 250 km track• hail swath 1200 km2 • 8 people injured• 15'000 cars damaged• several vineyards destroyed• Insured claims > €70 millions
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Hail swath on 18 July 2005• Hail crop damage claims (Swiss Hail Insurance)• Daily maximum grid-VIL• Daily maximum grid-VIL > 10 [kg/m2]
[kg/m2]0 20 40 60
540
km• Squares: communities where hail reported at least once
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Hail swath on 18 July 2005
• Maximum grid-VIL > 5 [kg/m2] (10:30-17:00 UTC)
• Hail crop damage locations (Swiss Hail Insurance)
[kg/m2]0 20 40 60
100
km
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Hail swath on 18 July 2005
• Maximum grid-VIL > 5 [kg/m2] (10:30-17:00 UTC)
• Hail crop damage locations (Swiss Hail Insurance)
• POH (Probability of Hail): Waldvogel et al. (1979)
C0dBZ 45 HH ΔH Hail: ΔH ≥ 1.4 km
3850 m
[%]20 40 60 80 1000
100
km
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Hail swath on 18 July 2005
• Maximum grid-VIL > 5 [kg/m2] (10:30-17:00 UTC)
• Hail crop damage locations (Swiss Hail Insurance)
• POH (Probability of Hail): Waldvogel et al. (1979)
C0dBZ 45 HH ΔH Hail: ΔH ≥ 1.4 km
3850 m
[%]20 40 60 80 1000
[kg/m2]0 20 40 60
VIL POH
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18.7.2005: cell-based attributes
Montreux (F2 tornado, 161 km/h)Geneva (F1 tornado)
18.7.2005
0
10
20
30
40
50
60
70
80
10:30 11:30 12:30 13:30 14:30 15:30
Time
[kg
/m2 ]
[
#/5m
in]
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
Alt
itu
de
[km
]
CGtot VIL EchoTop45 HmaxStormReflectivity
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18.7.2005: max cell-VIL distribution
VIL distribution145 trajectories (2630 cells); max >= 57 dBZ, duration >=30 min
25
3639
26
11
53
0
5
10
15
20
25
30
35
40
45
10-20 20-30 30-40 40-50 50-60 60-70 70-80
VIL [kg/m2]
Nu
mb
er
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Conclusions and outlook
• Reliable operational thunderstorms identification, tracking and 3D characterisation in Alpine area needs:• high resolution in height / time: 20-elev. (-0.3° / 40°) in 5 min
• dynamic reflectivity thresholding scheme: TRT
• multiple-radar composites
• Nowcasting in Alpine area: • use 3D storm attibutes VIL, 15/45 EchoTops, max storm refl.
altitude, CG for assessing the severe weather potential of thunderstorms
• combine grid-based 2D-animations and cell-based time trends
• Outlook Alpine area:• VIL: determine typical values, thresholds for occurrence of hail
• explore use of POH!? (Probability of Hail, Waldvogel et al.)
• extend time series analysis to forecast thunderstorm development (stage in its life cycle)
