HyMeX (*) V. Ducrocq (1), P. Drobinski (2) (1) GAME-CNRM,Météo-France & CNRS, Toulouse - (2) IPSL/LMD, Palaiseau & the HyMeX International Scientific Steering Committee (P. Lionello,J.T. Allen, P. Alpert, J. Backhaus, I. Braud, P. Chronis, S.Davolio, A. Dörnbrack, J. Font, J. Freer, S. Gualdi, E. Grunfest, V. Homar Santander, G. Madec, A. Montanari, T. Oguz, N. Pinardi, R. Rotunno, C. Sammari, Z. B. Su, I. Taupier-Letage, R. Therrien, R. Uijlenhoet, P. Viterbo, H. Wernli) & the HyMeX Working Group coordinators (K. Béranger, I. Braud, A. Chanzy, G. Delrieu, C. Estournel, E. Grunfest, S. Josey, B. Ivanèan-Picek, K. Lagouvardos, C. Llasat, W. Ludwig, C. Lutoff, A. Mariotti, A. Montanari, E. Richard, R. Romero, S. Somot, P. Viterbo) *Hydrological cycle in the Mediterranean eXperiment

Motivations and Societal Stakes The Mediterranean basin: A nearly enclosed sea surrounded by very urbanized littorals and mountains from which numerous rivers originate  A unique highly coupled system ( Ocean-Atmosphere- Continental surfaces)  Need to improve our knowledge on processes within each compartment, but also on processes at the interfaces and feedbacks in order to progress in the predictability of high-impact events and their evolution with global change.

 Gard, Sept. 2002: ~700 l/m 2, 1.2 billion € damage  Algiers, nov. 2001: ~260 l/m 2, 886 human losses Motivations and Societal Stakes  A region prone to high-impact events related to the water cycle:  Heavy precipitation, flash-flooding during fall  Severe cyclogeneses, strong winds, large swell during winters  Droughts, heat waves, forest fires during summers  Water resources: a critical issue  Freshwater is rare and unevenly distributed in a situation of increasing water demands and climate change Location of the maximum of daily precipitation Source: Météo-France >2 m/y 1-2 m/y m/y m/y m/y < 0.1 m/y Annual mean precipitation  30 M Mediterranean people, particularly in the South and East, are deprived of access to drinking water = 60% of the worldwide population lacking drinking water  During the second half of the 20th century, water demand has increased twofold (Source: Plan Bleu).

Motivations and Societal Stakes  The Mediterranean is one of the two main Hot Spot regions of the climate change Regional Climate Change Index, 20 models, 3 scenarios (Giorgi, 2006)  Climate is especially responsive to global change in Mediterranean  Large decrease in mean precipitation and increase in precipitation variability during dry (warm) season, large increase in temperature ( °C in 2100)

 to improve our understanding of the water cycle, with emphases on the predictability and evolution of intense events  by monitoring and modelling: the Mediterranean coupled system (atmosphere-land-ocean), its variability (from the event scale, to the seasonal and interannual scales) and characteristics over one decade in the context of global change  to evaluate the societal and economical vulnerability to extreme events and the adaptation capacity. Main Objectives Major disciplines: Meteorology, Oceanography, Hydrology, Climatology, Societal sciences In order to make progress in:  The understanding and modelling of key processes governing the Mediterranean water cycle, in particular those at the air-sea-land interfaces  The estimation of the components of the water budget (evaporation, precipitation, runoff, strait exchanges, water vapour transport) and their evolution with the climate change.  The validation of models (ocean, atmosphere, hydrology), including coupled models and development and validation of new parameterizations.

Main Scientific Topics Better understanding of the long-term water cycle over the Mediterranean basin: variability and trend

The Mediterranean Sea water budget acts on two major aspects of the Mediterranean circulation : - the yearly rate of dense water formation (inc. temperature and salinity)  drive the thermohaline circulation - the density of water flowing at the Gibraltar strait  influence the Atlantic ocean characteristics Mediterranean circulation Topic 1: Water budget of the Mediterranean Sea  Better estimation of the water budget components  Better knowledge of their variability at seasonal and interannual scales  Evolution with climate change ?  Impact of the localised intense events on the water budget E R P B D

Topic 2: Hydrological continental cycle  Top 10 rivers contribute ~50 % of the total input in the Mediterranean Sea, river run-off from small and intermittent rivers can account up to 40% in large floods 6-Ebre Jucar Segura 1-Rhône 2-Po 3-Drin- Buna 4-Nil 5-Neretva 7-Tevere 8-Adige 9-Seyhan 10-Ceyhan Evros Moulouya Chelif Medjerda Axios/ Vadar Strymon Gediz Menderez Asi-Orontes Source : Margat, 2004

Topic 2: Hydrological continental cycle  Top 10 rivers contribute ~50 % of the total input in the Mediterranean Sea, river run-off from small and intermittent rivers can account up to 40% in large floods  Dry summers, following by intense precipitation during the fall  high seasonal and interannual variability of discharges, aquifer recharges, vegetation and soil moisture content  Non-linear hydrological and hydraulic transfer functions due to both karstic and porous aquifers  Strong anthropogenic pressures, with recent changes in land use/land cover, strong urbanization and population growth  Better estimation and simulation of the natural and anthropogenic components of the continental hydrological cycle In order to better modeling and predict water resources, including soil water budget ( drought state, initial soil content prior to flash-flood), evapotranspiration and discharges.  at the regional scale (basin scale), with process studies at the local scale in order to improve their parameterizations Source : Plan Bleu

Main Scientific Topics Better understanding of the intense events: processes and contribution to the trend

Topic 3: Heavy precipitation and flash-flooding Large scale meteorological environment propitious to heavy precipitation events relatively well known, progress has to be made to better understand the mechanisms that govern the precise location of the anchoring region of the stationary precipitating systems as well as those that produce in some cases uncommon amount of precipitation Ducrocq et al, Sept Rainfall Totals: 700 l/m oct Rainfall totals: 470 l/m 2 Radar reflectivity

Topic 3: Heavy precipitation and flash-flooding Better observation and understanding of the hydrological and hydraulic responses to the heavy precipitation (contrasted topography, karstic soil, urban hydrology, soil moisture, debris flows, etc). Courtesy of G. Delrieu 22/09/ /09/ /09/1992 – 10:30 Flash flood along the Quliano River, Liguria Region (Italy) Le pont du Gard 9 September 2002

Topic 4: Intense air-sea exchanges Major sites of deep Water formation Major sites of dense Water formation Influence of coastal waters Key spots of intense air-sea exchanges (regional winds: Mistral, Bora,etc – deep cyclogeneses: Genea Gulf, etc)  dense water formation and deep ocean convection western Mediterranean cyclones climatology (Campins et al, 2006) Vents régionaux (D’après Lionello et al, 2006)  Better understanding of the dynamics and high interannual variability of the deep convection (occurrence, intensity), including the strong wind systems (cyclogeneses and regional winds) and the air-sea interaction

Topic 5: Vulnerability and adaptation capacity How to reduce the impacts of the extreme events and climate change ?

Topic 5: Vulnerability and adaptation capacity  Monitoring the vulnerability factors and adaptation strategies over one decade in the context of global change ( Water resources , and intense events  )  Evolution of risk perception  Social organisation and practices evolution  Develop indicators and observation methodologies to measure the evolution of the adaptation strategies

Interfaces with other programs HyMeX MerMeX Ocean Atmosphere CharMeX SicMED TerMeX PaleoMeX Continental surfaces BiodivMeX  Physical oceanography (dense water formation, ocean convection, coastal dynamics) => common cruises and measurement sites  River inputs (common supersites)  Impact of aerosols as CCN/ICN on precipitation, radiative effects of aerosols, impact on air-sea fluxes  common measurement sites on the Med Islands  Land surface description, common models at high resolution  common measurement sites, including North Africa and Eastern Mediteranaean  Lanslide, geology (karst)  GPS

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