HyMeX-SOP1, the field campaign dedicated to

heavy precipitation and flash-flooding

in Northwestern Mediterranean

V. Ducrocq (CNRM-GAME, Météo-France & CNRS)

E. Richard (CNRS & Univ. Toulouse)

with the HyMeX Executive Committee - SOP1 and many other contributions (~300 people involved in the field campaign)

http://www.hymex.org , http://sop.hymex.org

The HyMeX Program

HyMeX is a 10-y project devoted to the water cycle in Mediterranean, with

emphases on the predictability and evolution of high-impact weather events

(heavy precipitation, floods and flash-floods, droughts, strong winds and

ocean convection,...)

Within the long-term observation period (started in 2010), several Special

Observation Periods (SOP) have been planned for improving our process

understanding, modelling and forecasting capability of high-impact weather

events.

The first SOP series in Northwestern Mediterranean:

-SOP1: Heavy precipitation events (HPE) and flash-flooding

5 Sept.-6 Nov. 2012

- SOP2: Strong wind events and their impact on the ocean

convection and dense water formation

1 Feb. –15 March 2013

The HyMeX Program

HyMeX is a 10-y project devoted to the water cycle in Mediterranean, with

emphases on the predictability and evolution of high-impact weather events

(heavy precipitation, floods and flash-floods, droughts, strong winds and

ocean convection,...)

Within the long-term observation period (started in 2010), several Special

Observation Periods (SOP) have been planned for improving the process

understanding, modelling and forecasting capibility of high-impact weather

events.

The first SOP series in Northwestern Mediterranean:

-SOP1: Heavy precipitation events (HPE) and flash-flooding

5 Sept.-6 Nov. 2012

- SOP2: Strong wind events and their impact on the ocean

convection and dense water formation

1 Feb. –15 March 2013

Outline

State-of-art Knowledge on heavy precipitation and flash-flooding

Observation strategy

Design of the field campaign

The field campaign

Execution and coordination

Conclusion Successes and failures

State of art

Knowledge on Heavy Precipitation

and Flash-flooding

L

H

40-y composite analysis (ERA-40) for HPE over Southern France

(from Nuissier et al, 2011, QJ)

Synoptic environment

Postulate: the synoptic environment propitious to HPE is well known and

now rather well analysed/forecasted by global scale NWP systems.

Pattern resulting of Rossby wave breaking

at the end of the North Atlantic storm track

500 hPa Z Upper/mid-

troposphere

winds

Low-level

marine winds

Slow propagating pattern

Reduced statibility

Forcing for ascent

Strong low-level marine

moisture flux

Marine low-level flows

Heavy Precipitation area Low-level flow

Marine low-level flow facing the coastal mountain slopes

Strong orographic effects : chanelling, blocking/splitting/deflection

Dominant low-level flow with respect to heavy precipitation location

(from Ricard et al, 2012, JC

Davolio et al, 2012, HESSD)

deflection

Cold

pool

Orographic

forcing

convergence

French « Cévenol » cases

The characteristics of the marine low-level (conditionally unstable) flows

interacting with complex terrain modulate the location, intensity and stationarity

of the convective systems

Idealized simulations of stationarity MCS with the « true » terrain

(Bresson et al, QJRMS2012)

Convective

cells

MCS

stratiform

part Low-level

flow

Orographic

forcing

Cold pool

front

deflection

Low-level

convergence

#10

The Observation Strategy of SOP1

SOP1 objectives

25 oct. 2009

Most of the previous results have been obtained from numerical

model simulations. A dedicated field campaign was mandatory to

confirm these results by an observational-driven knowledge base.

HyMeX SOP1 aims to obtain detailed information on the following key

components:

the upstream marine flows and their interaction with complex

terrain

the air-sea exchanges and ocean mixed layer

the microphysics and dynamics of precipitating systems

leading to HPE

Distributed hydrological response of the Mediterranean

watersheds

The SOP1 domain and period

Criteria:

An area prone to heavy precipitation events with an expected number of events

in a 2 months period > 10 .

An area with operational meteorological and hydrological observations

networks well furnished to provide a high-level observation background that the

field campaign research instruments will complement.

A 2 month period centered on the climatological peak of convective heavy

precipitation events SOP1: from 5 September to 6 November 2012

Upstream Marine flows

Mobile on-alert instrumented platforms

over the maritime domain

Aircraft: ATR42 (WV lidar, aerosols), DO128

(in-situ, stable water isotopes),F20

(dropsondes)

Boundary layer balloons

Le Provence (RS)

Coastal observations

Radiosoundings (research,

oper.), wind profilers,

Supersites (Candillargues, San

Giuliano)

Instrumented sites in

Corsica (CO) and Menorca

(BA)

Lidars, RS, wind profilers

Le Provence

Mediterranean Sea Air-Sea fluxes

Le Provence (fluxes mast,

swell recorder)

Marisondes and SVP

Fixed MF buoys

SOO Marseille-Algiers

Upper ocean

Gliders (0-1000m), ARGO floats

Le Thethys cruise (Sept.) and Le Provence (3 IOP): CTD

MF buoys (mooring lines),Corsica channel mooring

IOP12

Le Tethys II - INSU

Bouée MF- Azur

Gliders – INSU

Le Provence

Precipitating systems

Microphysics and circulation within precipitating systems

F20 (cloud radar, microphysics probes)

Operational radars (Doppler, polarimetrics)

4 instrumented sites : CV, CI, CO, NEI

Surface precipitation

Oper. raingauges network, HPICONET,

disdrometers

Electrical activity precipitation

Lightning Mapping array, field mill, … in CV

CV

CO CI

NEI

Hydrological measurements

Hillslope (process

understanding on runoff

generation and concentration)

Soil moisture, infiltration, stable

water isotopes, geochemistry

small watersheds

Distributed hydrology

observations over

discharge, infiltration, soil moisture

Valescure, Tourgueuille, Avene,

Auzon

medium/large watersheds

(transfer in river and flooding)

Discharge and precipitation

estimation

Gard, Ardèche

Nested-catchment instrumentation

The Field Campaign execution

and coordination

The Heavy Precipitation Events

Ducrocq et al (2013)

20 days with at least 100mm/24h recorded by a raingauge station

HPE recorded over all the Northwestern Mediterranean, but more in Italy

The Intense Observation Periods (IOPs)

Flood in Spain

13 fatalities

Tornado in Marseille,

Nice airport closed

IOP13

IOP8

POI16a Flood in France

2 fatalities

IOP16b

Strong mistral, 2 fatalities

HPE- deep convection Strong winds

Instrument validation Shallow orographic precipitation

Squall Lines in Italy IOP6

IOPs types vs sites and time France

Spain

Italy

16 IOPs dedicated to HPE

Severe events with

fatalities and damages

France

Spain

Italy

POI14

Flooding in Lourdes

The Aircraft Missions

251 Flight hours:

SAFIRE/ATR42: 87 h

Survey of the upstream flow

Payload : WV Leandre II Lidar, aerosols,

turbulent air-sea fluxes

ATR42 Flight tracks

LV

Flight tracks available on google maps data visualisation

ATR 42 Flight AS41 28/09/2012 (1458-2016 UTC)

The Aircraft Missions

Airborne Leandre II lidar observations

The Aircraft Missions

251 Flight hours:

SAFIRE/F20: 69 h

Dynamics and microphysics within

precipitating systems

Payload :cloud radar, cold microphysics

probes, dropsondes launched over the Sea

F20 Flight tracks

Example of airborne measurements

Reflectivity from

the RASTA cloud

radar along the

Falcon flight

track – IOP13

17:10TU

21:00TU

RASTA radar -

Principles

Observed reflectivity and IR brightness temperature

+ lightning

Flight track- IOP13

The Aircraft Missions

251 Flight hours:

KIT/DO128: 95 h (11 Sept.-11 Oct.)

over and offshore Corsica

Payload : air-sea fluxes, stable water

vapour isotopes

+ T-NAWDEX flights : 32h (11-20 Oct.)

SOP1/IOP13

SOP1/IOP12a

SOP1/IOP14

SOP1/IOP15a

Related talks:

B. Adller , Tuesday 8:30

N. Kalthoff, Thursday 8:30

Balloons

•19 Boundary layer Balloons launched from Mahon

© CNES

Radiosoundings

About 850 radiosoundings

Targetable oper RS

MSLP and sensitive areas (ECMWF)

Valid time: 25 Oct.@18UTC

Verif time: 26 Oct.@18 UTC

~ 30 RS

from Le Provence 403 additional oper soundings at 06 & 18UTC (EUCOS)

using the DTS system

Trajectory and height

3 UTC-26 Oct

(IOP16a)

7km

350m

9 km

From HyMeX sites:

~ 250 RS in Corsica (San Giulano, Corte)

~160 RS along the French coast (Vias, Candillargues, Marseille, Fréjus)

~15 RS in Bologna, L’Aquila, Campoformido

One example of observations for the CV site

1

2 3 4

5

6

7 8

9

10

11

12

Nimes

Bollène

Lightning activity plotted as a

function of VHF source density per

10-min period

Convective Line - IOP6

00:00-07:50 UTC

0 10min

X X’

Z

Lightning Mapping Array

(12 stations)

The HyMeX Operation Center (HOC)

The HyMeX Operation Center (HOC) was located in La Grande Motte, close to the French

research aircraft base at Montpellier airport and the Candillargues supersite.

A coordination team composed of:

Scientific Director, Operation Director, Scientific

Secretary, forecaster, PI aircraft, PI ocean, PI

precipitation, PI Hydrology, PI winds, PI air-sea

fluxes, Logistics Coordination, Informatic support

The field campaign coordination

Main challenges:

- Aircraft: take-off time for day D and flight plans to be decided day D-1 before 11h forecast of

location and precise timing of deep convection 24-48h in advance

- Le Provence: Sea state (calm) to be forecasted 72h-48h in advance

- Balloons: 24-48h forecast of balloon trajectories: exclusively over the Sea and free of precip

- Radiosoundings: Not forget the short DTS deadlines !

A dedicated Météo-France forecaster at HOC

with a Météo-France forecaster workstation

(SYNERGIE)

Morning daily briefing 7/7, in visioconference

with L’Aquila, Palma, Mahon, San Giuliano,

Toulouse.

Several dedicated NWP systems for the SOP

(AROME_WMED over the whole Western

Mediterranean up to 48h, WRF for Italy,…):

25 output models available on the SOP website

The field campaign website

A dedicated website (sop.hymex.org) with a lot of observations and model

forecasts for: (i) real-time operations coordination; (ii) post-SOP analyses (model

evaluation, IOP studies,…)

Conclusions

25 oct. 2009

The field campaign has been successful regarding:

- the number of events observed: 23 IOPs, with 16 IOPs dedicated to HPE

over Italy, France and Spain.

- the variety of events: convective and squall lines, V-shape quasi-

stationary MCS, tornado, orographic precipitation, cyclogenesis,…

and with different levels of predictability that allow both (i) IOP process

studies and (ii) predictability studies (model improvement, data

assimilation), by synergistic use of SOP1 observations and models

Difficulties encountered:

- strong limitations imposed by the French Air Traffic Control, but impacts

attenuated thank to a dedicated controller and military zones (D54) over the

Sea.

-installation of the wind profilers in BA impossible although all our efforts,

but an interesting alternative has been found

- few flash-flood events over the CV watersheds, but EOP on-going…

Thanks for your attention !

http://www.hymex.org , http://sop.hymex.org

Hydrological response

Several factors influence flash-

floods:

- rainfall (spatial and timing

distribution)

- topography

- geology and soils

- initial soil moisture

- hydraulic transfer

Two main challenges:

- the change of scale problem

« how to transfer knowledge

acquired at a given scale to another

scale ? »

- prediction in ungauged basins

Cumulative distributions of regional model performances (over 19

watersheds in Cévennes-Vivarais, 8-9 Sep 2002 flash-flood)

L2: L1 + topography non-uniform

L3: L2 + rainfall non-uniform L4: L3 + initial water content non-uniform

Le Lay and Saulnier, 2007, GRL.

L5: L4 + soil parameters non-uniform

L6: L5 + velocity transfer parameters non-uniform

L1: uniform topography, rainfall, soils, velocities

transfer parameters and initial soil water

L3

L4

L6

L5

A Southern Alps case

• Interaction of the marine flows

with orography and cold pool

evidenced,

• but low-preditability of the event,

• few observations over the Sea for

data assimilation and for

verification of the model

Real case simulations of HPE : Var (Southern Alps) case in June 2010 Var, 15 June 2010

400mm/24h @ AFP – G.Julien

(Bresson et al, 2012)

Phase 1

Phase 2

A Southern Alps case

• Interaction of the marine flows

with orography and cold pool

evidenced,

• but low-preditability of the event,

• few observations over the Sea for

data assimilation and for

verification of the model

Real case simulations of HPE : Var (Southern Alps) case in June 2010 Var, 15 June 2010

400mm/24h @ AFP – G.Julien

(Bresson et al, 2012)

Phase 1

Phase 2

A low-level

marine flow

uptaking moisture

and energy from the

Mediterranean Sea,

along its path over

the Western

Mediterranean

rv gained from the sea

24h

Anticyclonic context

Cyclonic context E

vap

ora

tio

n f

lux

ove

r th

e S

ea

Residence time in the Mediterranean low-levels

anticyclonic situations Cyclonic situations

Origin and transport of moisture feeding the HPE, based on multiscale simulations

D

D-1

D-3

D-3 D-3

D

D-4

D-4

Origin and transport of moisture

Duffourg and Ducrocq (2011)

Water vapor

gained from the

Sea

1. Synoptic wave

(Rossby wave train)

adapted from F. Grazzini by Davolio (2012)

2. Low-level flow

3. Interaction with local

(orographic) features

This seems to be a common features

in the three convective events,

although with different intensity

Italian Liguria-Tuscany cases

25 Oct 2011

4 Nov. 2011

4 Oct. 2010

Very similar large

scale patterns

(resembling

condition for

Alpine HPE!)

#13

Le Provence missions

ATR42 flux measurements over Le Provence

3 missions :

IOP7a – 25-26 sept. Loc: 5.5 E/42.5 N

IOP12a – 11-12 Oct. Loc: 4.5 E/42.5 N

IOP16a – 25-27 Oct. Loc: 4.5 E/42.5 N

IOP12a

And also observations at sea…

4 gliders

~ 15 drifting buoys and ARGO floats

Ocean profiles from a R/V Le Tethys2 cruise

(Sept. Month)

A ship on alert (air-sea fluxes,

radiosoundings, swell recorder, ocean

profiles)

Ship of Opportunity measurements (regular

line Marseille- Algiers)

Additional instruments on fixed buoys

Bouée MF- Azur Bouée MF-Lion

Le Tethys II - INSU

Marisonde- MF houlographe- MF

Gliders – INSU

Le Provence – Phares & balises