usefulness of radar qpe for mediterranean flash …...ensemble forecasting of flash-flood, nhess,...

Usefulness of radar QPE for

Mediterranean flash-flood

ensemble forecasting

B. Vincendon, V. Ducrocq, O. Nuissier, B. Vié

GAME/CNRM (Météo-France, CNRS)Toulouse, France

[email protected]

ERAD 2012 - Toulouse –28 June 2012

HYdrological cycle in the Mediterranean Experiment

� « Time-nested » observation stategy :

� Aim : understanding of thewater cyclewith emphases onintense events

ERAD 2012 ERAD 2012 --22--

� First HYMEX Special Observation Period (SOP) :� North-Western Mediterranean

� from 5 September to 6 November 2012

� dedicated to Heavy Precipitation Events and FF.

� Additional observing systems deployed

� Real time meteorological and hydrological forecasting � e.g.for FF : ISBA-TOPMODEL

Accumulated rainfall (radar QPE) from 3 Nov. 2011 to 8 Nov. 2011

0

100

200

300

400

500

600

700

800

(mm)

� Uncertainty affects QPF even for high resolution NWP

FF forecasting within HYMEX

Observation

Simulation driven by radar QPE

Forecast with deterministic QPF

METEOROLOGICAL FORCINGMETEOROLOGICAL FORCING

Precipitation

AROME* QPFPrecipitation

Radar QPE

ISBAISBA--TOPMODEL*TOPMODEL**Bouilloud et al, 2010; Vincendon et al, 2010

*(Seity et al, 2011)

ERAD 2012 ERAD 2012 --33--

StreamflowStreamflow

800

900


Streamflow

Discharges from 3 Nov. 2011 @ 00UTC to 7 Nov. 2011 @ 00UTC

Ardèche riverGardons river

3 Nov. 4 Nov. 5 Nov. 6 Nov. 7 Nov. 3 Nov. 4 Nov. 5 Nov. 6 Nov. 7 Nov. 3 Nov. 4 Nov. 5 Nov. 6 Nov. 7 Nov. 3 Nov. 4 Nov. 5 Nov. 6 Nov. 7 Nov. 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011

3 Nov. 4 Nov. 5 Nov. 6 Nov. 3 Nov. 4 Nov. 5 Nov. 6 Nov. 3 Nov. 4 Nov. 5 Nov. 6 Nov. 3 Nov. 4 Nov. 5 Nov. 6 Nov. 7 Nov. 7 Nov. 7 Nov. 7 Nov. 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011

Assessment of high resolution QPF errors

� Climatology of differences between QPF and radar QPE

� Double penalty problem � object-oriented climatology of errors

� Objects defined according to thresholds in mm/h in the QPF and QPE fields

� PDF of amplitude and location errors

� Structure-Amplitude-Location* method

� measure of the QPF quality

QPE field

+

+

x qpe

ERAD 2012 ERAD 2012 --44--*(Wernli et al, 2008)

� no need to match objects one to one

QPF field

� S : difference in size , shape and gradientof the rainy objects

�A : normalized difference of averaged precipitation values

� L =L1 +L2

�L1 : global shift between QPE and QPF

�L2 : difference in relative positioning ofobjects in QPE and QPF

xqpf

+

SAL diagram

L component

A c

ompo

nent

Too much rain in QPF

Too small objects Too large objects Good forecast

False alarm

Convective rainfall

forecasted

Stratiformrainfallobserved

+2

ERAD 2012 ERAD 2012 --55--

A c

ompo

nent

S component

Not enough rain in QPF

and/or

too large a

gradient in QPF

and/or

too small a

gradient in QPF

Good forecast

No detection

Convectiverainfall

observed

Stratiform rainfall

forecasted

0

-20-2 +2

(Wernli et al, 2008)

Assessment of AROME QPF

L component

A c

ompo

nent

� A median value close to 0

� 1-h QPF vs 1-h QPE from Météo-France radar composite

� Days with significant rain from Sept. 2008 to Dec. 2011

ERAD 2012 ERAD 2012 --66--

A c

ompo

nent

S component

� A median value close to 0

⇒ No systematic bias

� L component

⇒ 70% of the cases with a location error < 50 km

� Valuable information in AROME QPF

SAL diagram for objects with 1-h rain over 2mm

Streamflow ensembles with ISBA-TOPMODELDeterministic AROME

Perturbation generation*

(*Vincendon et al., 2011)

PDF of amplitude and location errors

ERAD 2012 ERAD 2012 --77--

Single streamflow forecast

8 members streamflowensemble

ISBAISBA--TOPMODELTOPMODEL

30 members streamflowensemble

30 members

(*Vié et al., 2011)

8 m

em

be

rs

Real time FF forecasting chain within HYMEX SOP� Daily forecast:

Deterministic AROME

|

Day D+1

à 00utc

AROME + Perturbation

Forecasts with

ISBA-TOPMODEL driven by :

T0= Day D

à 00utc

|

T0+36 h

AROME + Perturbation : RPSS ~0.23

3 Nov. 2011 4 Nov. 2011

ERAD 2012 ERAD 2012 --88--

30 members

AROME EPS

8 members

AROME EPS: RPSS ~ 0.35

3 Nov. 2011 4 Nov. 2011

Streamflow ensembles for Gardons river : 3 nov. 2011 @ 02UTC - 4 nov. 2011 @ 04UTC

Observation

Simulation driven by radar QPE

Interquartile range of the ensemble

Ensemble median


Conclusions and future work� Usefulness of radar QPE for FF forecasting

⇒ To document the uncertainty on QPF

⇒ Method of perturbation of QPF to take benefit from valuable information of AROME deterministic forecast

⇒ Streamflow ensemble at reduced numerical cost

� Implemented in real-time for HYMEX SOP : http://sop.hymex.org

� Improvement of streamflow ensembles :

ERAD 2012 ERAD 2012 --99--

� Combining perturbation method with AROME EPS

� Considering other sources of uncertainty :

� Hydrological modelling

� Initial soil conditions

� Benefit from HYMEX SOP to : � Intercompare FF forecasts on HYMEX cases

� Assess ensemble forecasting on a satisfactory sample

� Improve initialisation and calibration of hydrological models

Bouilloud et al, 2010 :Bouilloud L., K. Chancibault, B. Vincendon, V. Ducrocq, F. Habets, G.M. Saulnier, S. Anquetin, E. Martin, J. Noilhan , 2009: An advanced coupling between the ISBA land surface model and the TOPMODEL hydrological model to simulate Mediterranean flash-floods, J. Hydrometeor., 11(2),315-333

Vié et al, 2011 :Vié, B., Nuissier, O., Ducrocq, V., 2010: Cloud-resolving ensemble simulations of heavy precipitating events : uncertainty on initial conditions and lateral boundary conditions, Mon. Weath. Rev.,139,403-423

Vincendon et al, 2010 :Vincendon B.,Ducrocq V., Saulnier G.M.; Bouilloud L., Chancibault K., Habets F., Noilhan J., 2010:

Thank you

ERAD 2012 ERAD 2012 --1010--

Vincendon B.,Ducrocq V., Saulnier G.M.; Bouilloud L., Chancibault K., Habets F., Noilhan J., 2010: Advantages of coupling the ISBA land surface model with a TOPMODEL hydrological model dedicated to Mediterranean flash floods, J. Hydrology, 394(1-2), 256-266

Vincendon et al, 2011 :Vincendon B., Ducrocq V., Nuissier O. et Vié B. , 2011:Introducing perturbation in rainfall fields for an ensemble forecasting of flash-flood, NHESS, 11, 1529-1544

Wernli et al, 2008 :Wernli H., Paulat M., Heigen M. and Frei C., 2008 : SAL A novel quality measure for the verification of quantitative precipitation forecast , Mon. Weath. Rev., 136,4470-4487

Point-to-point assessment of QPF values

D

� A : characterizes how different are domain-averaged precipitation values

QPE field

QPF field

ERAD 2012 ERAD 2012 --1111--*(Wernli et al, 2008)

Observed D-averaged precipitation

Modelled D-averaged precipitation

QPF field


� L =L1 +L2

� L1 characterizes the global shift between QPE and QPF

Barycentre of the QPE field among D

Maximal distance among D

D

+

x(Rmod)+

x(Robs)

d

Object n

nx+

Rn

ERAD 2012 ERAD 2012 --1212--

� L2 characterizes the spatial precipitation distribution inside the domain.

(Wernli et al, 2008)

Barycentre of object n

Mean rainfall on object n

Total number of objects


� S: characterizes the size of the rainy objects as well as the gradient

D

Object n

ERAD 2012 ERAD 2012 --1313--(Wernli et al, 2008)

Maximal rainfall on object n

Usefullness of radar QPE for FF forecasting?

� Hydrological models dedicated to FF sensitive to rainfall (volume and spatial distribution)

⇒ Radar QPE = appropriate information

METEOROLOGICAL FORCINGMETEOROLOGICAL FORCING

Precipitation

Radar QPE

Coupled system ISBAISBA--TOPMODELTOPMODEL**

� FF simulation:

ERAD 2012 ERAD 2012 --1414--

Surface schemeISBA

Routing

Hydrological model TOPMODEL

Streamflow

Initial soil

conditions

*Bouilloud et al, 2010; Vincendon et al, 2010

�!

� Use of radar QPE for :

� hydrological simulation

� hydrological models calibration

Uncertainty on FF simulations due to QPE

• Paris

Rivers:

Ardèche at Saint Martin (2240 km²)

Cèze at Bagnols-sur-Cèze (1100 km²)

Gardons at Ners (1090km²)

ERAD 2012 ERAD 2012 --1515--

Bollène•Toulouse

Nîmes

Montpellier• •

•MontAigoual

0-4040-110110-190190-270270-370370-500500-650650-800800-980980-11801180-14301430-17301730-20502050-24002400-28302830-4760

Altitude (en m)

(C)

ME

TE

O-F

RA

NC

E /

IGN

Weather radars

Hydrological range (80 km)

Uncertainty on FF simulations due to QPE: November 2011 case

0

100

200

300

400

500

600

700

800

(mm)QPEs (mm) from 3rd nov. 2011 at 12UTC to 8 nov. 2011 at 00UTC

ERAD 2012 ERAD 2012 --1616--

900Bollène radar MosaicNîmes radar

Discharges (m3.s-1) from 3rd nov. 2011 at 12UTC to 8 nov. 2011 at 00UTC

Ardèche river Gardons river

Uncertainty on FF simulations due to QPE: November 2011 caseS

ever

al p

aram

eter

s

ERAD 2012 ERAD 2012 --1717--Discharges (m3.s-1) from 3rd nov. 2011 at 12UTC to 8 nov. 2011 at 00UTC

Ardèche river Gardons river

Sev

eral

rad

ar d

ata

Sensitivity to radar QPE time stepTemporal frequency:

1h

15 minutes

05 minutes

Catchments with an area < 200 km²

ERAD 2012 ERAD 2012 --1818--

area < 200 km²

Catchments with an area > 600 km²

Cumulated frequencies of nash efficiency (Prediflood project)

Quantification of AROME QPF error� PDF of amplitude and location errors for object Or and Oc

� Amplitude errors : no systematic bias

� Location errors : < 50 km in 70% of cases

ERAD 2012 ERAD 2012 --1919--PDF of location errors for Or objects along E/W axe(Vincendon et al., NHESS, in revision)

Quantification of AROME QPF error

�AROME hourly QPF vs Météo-France radar hourly QPE

� Significant rainy events

� Object–based climatology of AROME QPF errors :

� Rainy objects = Or

� Convective objects = Oc

Or

ERAD 2012 ERAD 2012 --2020--

1h-radar QPE the 01 Nov. 2008 at 20UTC 1h-AROME QPF the 01 Nov. 2008 at 20UTC(AROME run start = 01/11/2008 analyse)

Or

Oc

1h-radar QPE the 01 Nov. 2008 at 20UTC 1h-AROME QPF the 01 Nov. 2008 at 20UTC(AROME run start = 01/11/2008 analyse)

Quantification of AROME QPF error

ERAD 2012 ERAD 2012 --2121--

D

Perturbation generation method

PDF of location errors

(Vincendon et al., NHESS, in revision)

AROME déterministic forecast

Or

Oc

N members selected

PDF of

ERAD 2012 ERAD 2012 --2222--

D

Nnew fields

D

PDF of amplitude errors for Oc

fc

OcRainfall intensity of Or

X fPDF of amplitude errors for Or

f

Rainfall intensity of Oc X fc

Ardèche

Cèze

(m3 /

s)

(m3 /

s)


21 October 2008 22 October 2008

Streamflow ensemble for 21-22 October 2008 event

ERAD 2012 ERAD 2012 --2323--

Gardons

(m3 /

s)

21 October 2008 22 October 200821 October 2008 22 October 2008

21 October 2008 22 October 2008

Ensemble median

Interquartiles range

Discharges simulated from :

50 members of the ensemble

Observed discharge

deterministic AROME

Ardèche

Cèze

(m3 /

s)

(m3 /

s)


01 November 2008 02 November 2008

Streamflow ensemble for 01-02 November 2008 event

ERAD 2012 ERAD 2012 --2424--

Gardons

(m3 /

s)




Ensemble median

Interquartiles range

Discharges simulated from :

50 members of the ensemble

Observed discharge

deterministic AROME

Early verification

� RPSS ~ 0.35 mm/day on 24h-accumulated rainfall ⇒ Ensemble forecast > deterministic forecast

Gardons Perturbation method

(m3/s)� Comparison to a research AROME EPS (Vié et al., 2010)

⇒ Close results

ERAD 2012 ERAD 2012 --2525--

AROME EPS

�Advantage of the perturbation method:

� Reduced numerical cost

� Lot of members

How do we simulate Mediterranean FF?

d2

d3

∆xw2

w3

Runoff RDeep drainage

ISBA-3L :Management of water and energy at surface / atmosphere interface

WI,tW’

R

DR

Surface scheme resolution∆x = 1km / ∆t = 15min.

ERAD 2012 ERAD 2012 --2626--

TOPMODEL :Lateral water transfer within the catchments

ROUTING MODULE:Water transfer along slopes and

rivers

QtotCatchments resolution

δx = 50m / δt = 1h

δx

di,td’ i,t

Deep drainage DRdi,t= f( WI,t ) W’ I,t = f( d’i,t )

|

Day D-2

à 00utc

|

Day D-1

à 00utc

Radar QPE:

Spin-up period =>Simulation with


Real time FF forecasting chain within HYMEX SOP

� Daily forecast :

Deterministic AROME

|

Day D+1

à 00utc

|

Day D+2

à 00utc

Forecasts with


|

Day D

à 00utc

Climatology of amplitude and

ERAD 2012 ERAD 2012 --2727--

Initial soil conditions

Radar QPE:

RR1h AROME perturbated

30 members

AROME EPS

8 members

� Usefullness of radar QPE in this framework?� FF simulation � QPF assessment

amplitude and location errors

usefulness of radar qpe for mediterranean flash …...ensemble forecasting of flash-flood, nhess,...

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