HyMeX-SOP1, the field campaign dedicated to heavy precipitation and flash-flooding in Northwestern Mediterranean

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HyMeX-SOP1, the field campaign dedicated to heavy precipitation and flash-flooding in Northwestern Mediterranean V. Ducrocq (CNRM-GAME, Météo-France & CNRS) E.

1 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)

2 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 SOP2: Strong wind events and their impact on the ocean convection and dense water formation 1 Feb. 15 March 2013

3 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 SOP2: Strong wind events and their impact on the ocean convection and dense water formation 1 Feb. 15 March 2013

4 State-of-art Outline Knowledge on heavy precipitation and flash-flooding Observation strategy Design of the field campaign The field campaign Execution and coordination Conclusion Successes and failures

5 State of art Knowledge on Heavy Precipitation and Flash-flooding

6 Synoptic environment Pattern resulting of Rossby wave breaking at the end of the North Atlantic storm track L 500 hpa Z Upper/midtroposphere winds Low-level marine winds Slow propagating pattern 40-y composite analysis (ERA-40) for HPE over Southern France (from Nuissier et al, 2011, QJ) H Reduced statibility Forcing for ascent Strong low-level marine moisture flux Postulate: the synoptic environment propitious to HPE is well known and now rather well analysed/forecasted by global scale NWP systems.

Marine low-level flows Dominant low-level flow with respect to heavy precipitation location Heavy Precipitation area Low-level flow (from Ricard et al, 2012,

7 Marine low-level flows Dominant low-level flow with respect to heavy precipitation location Heavy Precipitation area Low-level flow (from Ricard et al, 2012, JC Davolio et al, 2012, HESSD) Marine low-level flow facing the coastal mountain slopes Strong orographic effects : chanelling, blocking/splitting/deflection

French «Cévenol» cases Idealized simulations of stationarity MCS with the «true» terrain Orographic forcing Cold pool deflection convergence Convective cells MCS stratiform part Low-level flow

8 French «Cévenol» cases Idealized simulations of stationarity MCS with the «true» terrain Orographic forcing Cold pool deflection convergence Convective cells MCS stratiform part Low-level flow Orographic forcing Cold pool front deflection Low-level convergence (Bresson et al, QJRMS2012) The characteristics of the marine low-level (conditionally unstable) flows interacting with complex terrain modulate the location, intensity and stationarity of the convective systems #10

9 The Observation Strategy of SOP1

10 SOP1 objectives 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 25 oct. 2009

11 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

12 Upstream Marine flows Coastal observations Radiosoundings (research, oper.), wind profilers, Supersites (Candillargues, San Giuliano) Le Provence 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) Instrumented sites in Corsica (CO) and Menorca (BA) Lidars, RS, wind profilers

Mediterranean Sea Air-Sea fluxes Le Provence (fluxes mast, swell recorder) Marisondes and SVP Fixed MF buoys SOO Marseille-Algiers Le Provence Bouée MF- Azur IOP12 Gliders

13 Mediterranean Sea Air-Sea fluxes Le Provence (fluxes mast, swell recorder) Marisondes and SVP Fixed MF buoys SOO Marseille-Algiers Le Provence Bouée MF- Azur IOP12 Gliders INSU Le Tethys II - INSU Upper ocean Gliders (0-1000m), ARGO floats Le Thethys cruise (Sept.) and Le Provence (3 IOP): CTD MF buoys (mooring lines),corsica channel mooring

Precipitating systems Microphysics and circulation within precipitating systems F20 (cloud radar, microphysics probes) Operational radars (Doppler, polarimetrics) 4 instrumented

14 Precipitating systems Microphysics and circulation within precipitating systems F20 (cloud radar, microphysics probes) Operational radars (Doppler, polarimetrics) 4 instrumented sites : CV, CI, CO, NEI Electrical activity precipitation Lightning Mapping array, field mill, in CV CV NEI CO CI Surface precipitation Oper. raingauges network, HPICONET, disdrometers

Nested-catchment instrumentation Hydrological measurements medium/large watersheds (transfer in river and flooding) Discharge and precipitation estimation Gard, Ardèche small watersheds Distributed

15 Nested-catchment instrumentation Hydrological measurements medium/large watersheds (transfer in river and flooding) Discharge and precipitation estimation Gard, Ardèche small watersheds Distributed hydrology observations over discharge, infiltration, soil moisture Valescure, Tourgueuille, Avene, Auzon Hillslope (process understanding on runoff generation and concentration) Soil moisture, infiltration, stable water isotopes, geochemistry

16 The Field Campaign execution and coordination

17 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

18 The Intense Observation Periods (IOPs) France Spain IOPs types vs sites and time Flood in Spain 13 fatalities Italy IOP8 Flood in France 2 fatalities POI16a France Spain Italy Strong mistral, 2 fatalities HPE- deep convection Shallow orographic precipitation Strong winds Instrument validation IOP16b 16 IOPs dedicated to HPE Flooding in Lourdes IOP6 Squall Lines in Italy IOP13 Severe events with fatalities and damages POI14 Tornado in Marseille, Nice airport closed

19 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 Flight tracks available on google maps data visualisation LV

20 The Aircraft Missions Airborne Leandre II lidar observations ATR 42 Flight AS41 28/09/2012 ( UTC)

21 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

22 Example of airborne measurements RASTA radar - Principles Reflectivity from the RASTA cloud radar along the Falcon flight track IOP13 17:10TU Observed reflectivity and IR brightness temperature + lightning Flight track- IOP13 21:00TU

The Aircraft Missions 251 Flight hours: KIT/DO128:

24 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 Related talks: B. Adller, Tuesday 8:30 N. Kalthoff, Thursday 8:30 + T-NAWDEX flights : 32h (11-20 Oct.) SOP1/IOP12a SOP1/IOP13 SOP1/IOP14 SOP1/IOP15a

25 CNES Balloons 19 Boundary layer Balloons launched from Mahon

Radiosoundings About 850 radiosoundings From HyMeX sites: ~

French coast (Vias, Candillargues, Marseille, Fréjus) ~15

soundings at 06 & 18UTC (EUCOS) using the DTS system ~ 30

sensitive areas (ECMWF) Valid time: 25 Oct.

26 Radiosoundings About 850 radiosoundings 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 403 additional oper soundings at 06 & 18UTC (EUCOS) using the DTS system ~ 30 RS from Le Provence Targetable oper RS 9 km 350m MSLP and sensitive areas (ECMWF) Valid time: 25 Oct.@18UTC Verif time: 26 Oct.@18 UTC 7km Trajectory and height 3 UTC-26 Oct (IOP16a)

Convective Line - IOP6 00:00-07:50 UTC Z 0 10min 9 11 X X 8 10

27 One example of observations for the CV site Lightning activity plotted as a function of VHF source density per 10-min period Convective Line - IOP6 00:00-07:50 UTC Z 0 10min 9 11 X X Bollène Nimes Lightning Mapping Array (12 stations)

The HyMeX Operation Center (HOC) The HyMeX Operation Center (HOC) was

at Montpellier airport and the Candillargues supersite.

Director, Scientific Secretary, forecaster, PI aircraft, PI ocean, PI

28 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

29 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

30 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, )

31 Conclusions 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 quasistationary 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 25 oct. 2009

32 Thanks for your attention!

33 Hydrological response Several factors influence flashfloods: Cumulative distributions of regional model performances (over 19 watersheds in Cévennes-Vivarais, 8-9 Sep 2002 flash-flood) - rainfall (spatial and timing distribution) - topography - geology and soils - initial soil moisture - hydraulic transfer Two main challenges: L3 L4 L5 L6 - the change of scale problem «how to transfer knowledge acquired at a given scale to another scale?» - prediction in ungauged basins L1: uniform topography, rainfall, soils, velocities transfer parameters and initial soil water L2: L1 + topography non-uniform L3: L2 + rainfall non-uniform L4: L3 + initial water content non-uniform L5: L4 + soil parameters non-uniform L6: L5 + velocity transfer parameters non-uniform Le Lay and Saulnier, 2007, GRL.

34 A Southern Alps case Real case simulations of HPE : Var (Southern Alps) case in June 2010 Phase 1 Var, 15 June 2010 AFP G.Julien Phase 2 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 (Bresson et al, 2012)

orography and cold pool evidenced, but low-preditability of

35 A Southern Alps case Real case simulations of HPE : Var (Southern Alps) case in June 2010 Phase 1 Var, 15 June 2010 AFP G.Julien Phase 2 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 (Bresson et al, 2012)

from the rv gained from the sea Sea A low-level marine flow uptaking moisture and energy from the Mediterranean Sea, along its

36 Evaporation flux over the Sea D-4 Origin and transport of moisture feeding the HPE, based on multiscale simulations anticyclonic situations D-4 D D-3 D-3 Origin and transport of moisture Cyclonic situations D-3 Anticyclonic context D D-1 Water vapor gained from the rv gained from the sea Sea A low-level marine flow uptaking moisture and energy from the Mediterranean Sea, along its path over the Western Mediterranean Cyclonic context 24h Residence time in the Mediterranean low-levels Duffourg and Ducrocq (2011)

Italian Liguria-Tuscany cases 25 Oct 2011 1.

Interaction with local (orographic) features 4

(resembling condition for Alpine HPE!) 2.

2010 This seems to be a common features in the

37 Italian Liguria-Tuscany cases 25 Oct Synoptic wave (Rossby wave train) 3. Interaction with local (orographic) features 4 Nov Very similar large scale patterns (resembling condition for Alpine HPE!) 2. Low-level flow 4 Oct This seems to be a common features in the three convective events, although with different intensity adapted from F. Grazzini by Davolio (2012) #13

3 missions : IOP7a 25-26 sept. Loc: 5.5 E/42.

38 3 missions : IOP7a sept. Loc: 5.5 E/42.5 N IOP12a Oct. Loc: 4.5 E/42.5 N IOP16a Oct. Loc: 4.5 E/42.5 N Le Provence missions ATR42 flux measurements over Le Provence IOP12a

And also observations at sea 4 gliders ~ 15 drifting

Ocean profiles from a R/V Le Tethys2 cruise (Sept.

radiosoundings, swell recorder, ocean profiles) Le

houlographe- MF Bouée MF-Lion Ship of Opportunity

39 And also observations at sea 4 gliders ~ 15 drifting buoys and ARGO floats Gliders INSU Le Tethys II - INSU Ocean profiles from a R/V Le Tethys2 cruise (Sept. Month) A ship on alert (air-sea fluxes, radiosoundings, swell recorder, ocean profiles) Le Provence Phares & balises Marisonde- MF Bouée MF- Azur houlographe- MF Bouée MF-Lion Ship of Opportunity measurements (regular line Marseille- Algiers) Additional instruments on fixed buoys

WG3 Heavy precipitation, flash-floods and floods. Guy Delrieu, Alberto Montanari Romualdo Romero, Evelyne Richard

WG3 Heavy precipitation, flash-floods and floods Guy Delrieu, Alberto Montanari Romualdo Romero, Evelyne Richard Scientific questions WG3-SQ1: What are the characteristics of extreme hydro-meteorological