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The flash flood event of June 2000 in Catalonia: The flash flood event of June 2000 in Catalonia: monitoring and nowcasting using the monitoring and nowcasting using the
meteorological radar and an automatic meteorological radar and an automatic raingauge networkraingauge network
MARÍA DEL CARMEN LLASAT MARÍA DEL CARMEN LLASAT TOMEU RIGOTOMEU RIGO
Meteorological Hazards Analysis Team Meteorological Hazards Analysis Team Department of Astronomy & MeteorologyDepartment of Astronomy & MeteorologyUniversity of Barcelona, SpainUniversity of Barcelona, [email protected] http://www.am.ub.es/~carmell
INTERREG IIIC: HYDROPTIMET MEETING. GRENOBLE 2-3 FEBRUARY 2004
During the early morning of 10 June 2000 there occurred a heavy rainfall event over Catalonia (NE of Spain) that caused material damages estimated at over 65,000,000 euros and there were 5 fatalities.
A short diagnosis of the event
Location of the event
The affected region is placed at NE of the Spain.
It is named Internal Basins of Catalonia and it consists of 4 larger basins (Ter, Besos, Llobregat and Francoli) and other smaller ones.
DataRaingauge data in surfaceRadar imageryRadiosoundings of Barcelona
and Palma MallorcaSynoptic analysisMesoscale analysis
Acknowledgements for the data: Agencia Catalana de l’Aigua, Instituto Nacional de Meteorología, Servei de Meteorologia de Catalunya
Our special acknowledgement to E. Velasco (ACA) and P. Martín (INM) for their collaboration
The raingauge network
* Rain gaugeWhite area: IBC
The SAIH system of the IBC covers an area of 16000 km2.
The rainfall network is composed by 126 tipping-bucket automatic rain gauges.
The precipitation is cumulated and recorded every 5 minutes.
Rainfall overturning of 0.1 mm.
The meteorological radar
Range 240 km (normalmode)
120 km (Dopplermode)
First elevationaltitude(degrees)
0.5º 0.5º
Number oflevels
20 8
PRF 250Hz 900/1200 HzFrequency 5600-5650 MHzPolarization Horizontal
Placed over the Puig de les Agulles (20 km at SW of Barcelona) at 612 m asl.
It belongs to the INM radar network and operates in the C-band.
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Total Cumulated Rainfall
The 94% of the rainfall gauges of the IBC registered a cumulated rainfall above 15 mm in 24 hours.
A lot of 24 hours maximum rainfall values exceeding the 100 mm were recorded in many gauges of the Llobregat Basin and other minor basins.
Some examples of maximum values registered are:
• 223 mm in 24 hours
• 158 mm in 3 hours
• 13.2 mm in 5 minutes
21:00 UTC 9 June- 21:00 UTC 10 June
The maximum 5-minutal rainfall value (13.2 mm) is equivalent to 154.8 mm in only one hour.
Rainfall Rate and Time Evolution
The rainfall event started at the Southern Basins at 21:30 UTC as a consequence of the pass of a quasi-stationary rainfall band, that remained over the same place for about 2 hours.
Flow evolution
Synoptic Evolution
On 10 June at 0000 UTC:
• Previously: anticyclonic situation, warm and very wet advection in low levels, great potential instability
•the cold front was situated around the west of Catalonia.
• in the previous few hours to the event, a surface depression (1008 hPa) had been forming, centred on the Balearic Islands.
• the flow from the west that dominated most of the Peninsula at 850 hPa had been veering, so that by that time it was coming mainly from the north and had advected very cold air that extended right to the upper troposphere
Barcelona Palma
Madrid Murcia
The day of the floods:
10 June
(00 UTC)
Cross sections 10/06/00
00 UTC 12 UTC
LISBOA- MADRID- MURCIA-BARCELONA-PALMA-CAGLIARI
pe p
Mesoscale analysis
L
It showed a conjunction of the following factors:
Mesoscalar depression at surface. It led to the convergence of water vapour at low levels and played a direct role in triggering the potential instability cumulated previously
•2. the existence of a line of convergence, which advance over Catalonia along a SW-NE axis, with the slow movement of the depression. The squall lines were formed near of it.
Lecture of wind profile
Identification of convective cells
Identification of 2D precipitation structures
Tracking of convective cells
Nowcasting of convective cells
Tracking of 2D precipitation structures
Nowcasting of 2D precipitation structures
Warning of floodsor other severe events
Data base of convectivestructures (2D & 3D)
Lecture of wind profile
Identification of convective cells
Identification of 2D precipitation structures
Tracking of convective cells
Nowcasting of convective cells
Tracking of 2D precipitation structures
Nowcasting of 2D precipitation structures
Warning of floodsor other severe events
Data base of convectivestructures (2D & 3D)
The radar tool• Interaction between the 2 procedures
(2D&3D), adapting, improving and combining different algorithms
• 2D: rainfall structures (separating convective & stratiform precipitation)
• 3D: convective cells
• Use of the wind profile over the meteorological radar for tracking and nowcasting 2D&3D structures
• Warnings production
To classify convective structures in 2D
To identify convective structures in 3D
2D
3D
Mesoscale Convective System
Multi-Cell Storm
To integrate cells and convective structures
The method (Johnson et al., 1998) uses the centroid position and other features (size, shape and intensity) of 3D cells of the 6 previous images.
For each “actual” cell identifiyed, the algorithm has tried to detect “past” cells which distance was less than 10 km. The other features help to describe the state and the life-cycle of the cell.
However, for cases where two cells could be associated to the same “previous” 3D structure, those features, combined with distance, can help to determine which is the selected.
Tracking and nowcasting of cells
nowpast
future
Forecasted position
Real position
Application to rainfall nowcasting
Application to rainfall nowcasting
Tracking and nowcasting of cells
Cells can move throughout the convective system or in the same direction that the 2D structure. First case is the most dangerous: slow or null cells movement can
gives strong rainfall values over the same zone
Previous positions have not been used. Reason: in general, positions of 2D structures changes extraordinarily in 10 minutes.
The displacement vector has been obtained by combining two different vectors:
• mean wind vector at mid-levels (HIRLAM data)
• mean movement vector of convective cells associated to that structure
Tracking and nowcasting of convective structures 2D+3D
Application to rainfall nowcasting
Example of tracking and nowcasting
2D3D
Example of tracking and nowcasting
Now
Tracking
Nowcasting
Nowcasting
Now
Application to rainfall nowcasting
Past: t-60-t0 Future: t0-t+60
Tracking & Warning
Application to rainfall nowcasting
Application to rainfall nowcasting
Radar image at 22:40 UTC
Z = 800 R1.6
The next stepsTo apply this methodology to other eventsTo improve the analysis using lightning dataTo apply objective mesoscale models (see contribution UIB) To obtain the nowcasted rainfall chart by applying the suitable algorithms (convective and stratiform relationships) in order to improve the flood warning system To integrate with hydrological models
Thanks for your attention
