Ocean-atmosphere coupling for prediction of Mediterranean heavy

Ocean-atmosphere coupling for prediction of Mediterranean heavy precipitation events:
better modeling and impacts of river run-off and sea state
3-y PhD Position
Place : CNRM, Toulouse, France
The Western Mediterranean regions are prone to heavy precipitation. Daily rainfall amounts above
150 mm are not uncommon, possibly leading to flash-flooding. The marine strong winds that
frequently prevail during heavy precipitation events increase the evaporation from the
Mediterranean Sea and transport towards the coastal regions low-level moist air that feeds the heavy
precipitation systems. The low-level strong winds also disturb the coastal upper-ocean circulation
and contribute sometimes to accentuate flooding by the swell and waves. For instance, a major
precipitation event occurred in December 2003 leading to a historical flooding over Southern
France, with the Rhône river peaking to 13000m 3/s. The strong south to southeasterly winds (gusts
up to 100-150km/h), associated with high waves (up to 8m) and storm surge (~0.8m) disturbed the
Rhône river run-off at Sea and accentuated the flooding.
HyMeX (www.hymex.org) is an international research program devoted to the understanding of
the Mediterranean water cycle with emphasis on high-impact weather events in order to better
predict them. Within the framework of HyMeX, CNRM designed fine-scale coupled modeling
systems in order to better understand the interactions between atmosphere, sea and continental
hydrology and their role in producing heavy precipitation events and associated impacts (Lebeaupin
Brossier, 2007 ; Vincendon, 2010). During the recent years, a coupled ocean-atmosphere model at
kilometric resolution over the western Mediterranean has been developed, based on the MétéoFrance operational atmospheric model AROME (Seity et al., 2011; Fourrié et al., 2015) and the
NEMO ocean model (Madec, 2008). The impact of the coupling on the prediction of two heavy
precipitation events observed during the first HyMeX field campaign in autumn 2012 (Ducrocq et
al., 2014) has been assessed (Rainaud, 2015).
The overarching objective of the PhD project is to improve the understanding and modeling of
the atmosphere-ocean-waves-continental hydrology coupled processes during heavy precipitation
and flash-flooding events through:
(i) A better modeling of the river discharges and run-off in the AROME-NEMO coupled modeling
system through interfacing the system with high-frequency and fine scale observations and analyzed
discharges, combined with a better description of the vertical run-off. The aim is to better represent
the fresh water input to the sea and the main river plumes such as the Rhône one and their impact on
the ocean circulation. The study will investigate the impacts on the local ocean stratification, the
turbulence within and at the edge of the river plume, the upper-ocean currents near the river mouth,
specifically during and just after a flash-flooding event.
(ii) A better modeling of the waves effect in the AROME-NEMO coupled modeling system. As a
first step, the waves will be taken into account in the estimation of the air-sea turbulent fluxes
using wave effect parameterizations as in Thévenot et al. (2015). Then, the integration of the
Météo-France operational wave model MFWAM to the AROME-NEMO system will allow to
examine the coupled processes between ocean-waves-atmosphere-river run-off for several case
studies from HyMeX. Ocean and atmospheric water and heat budgets will be used to analyze the
coupled processes during heavy precipitation and flash-flooding events.
Supervisors
Dr Cindy Lebeaupin Brossier, Dr Marie-Noëlle Bouin (HDR), Dr Véronique Ducrocq (HDR)
About CNRM and the PhD Funding
The French National Center for Meteorological Researches (CNRM, www.cnrm-game-meteo.fr),
affiliated as a joint research Unit (UMR 3589) to Météo-France and CNRS, account eighty
researchers and hundred and fifty engineers, technicians and administration staff. CNRM hosts
between fifteen to twenty new doctoral students each year.
The PhD project is submitted to the doctoral research support of the Languedoc-Roussillon MidiPyrenees Region for a half grant, the other half is funded by Météo-France.
Qualifications and experience required
Candidates are expected to have a Master-of-Science-equivalent university degree when they start
their Ph.D. project, preferably related to ocean physics, atmospheric sciences or geophysics. The
candidates should be under 35 years of age.
Good communication skills in both written and spoken English, good experience in scientific
programming and interest in numerical simulations on supercomputers are seeking.
Application:
Candidates should send a Curriculum Vitae and copies of education certificates including university
transcripts of grades, a cover letter describing background, training and research interests and the
contact information of two referees to:
[email protected] and [email protected]
Application deadline is April 27, 2016.
References
Ducrocq, V., et al, 2014: HyMeX-SOP1, the field campaign dedicated to heavy precipitation and flash-flooding in
Northwestern Mediterranean. Bull. Amer. Meteorol. Soc., 95,1083–1100, doi:10.1175/BAMS-D-12-00244.1
Fourrié, N., E. Bresson, M. Nuret, C. Jany, P. Brousseau, A. Doerenbecher, M. Kreitz, O. Nuissier, E. Sevault, H.
Bénichou, M. Amodei, F. Pouponneau, 2015 : AROME-WMED, a real-time mesoscale model designed for HyMeX
Special Observation Periods. Geosci. Model Dev., 8, 1919-1941, doi :10.5194/gmd-8-1919-2015.
Lebeaupin Brossier, C., 2007: Etude du couplage océan-atmosphère associé aux épisodes de pluie intense en région
méditerranéenne. PhD. Thesis, Univ. P. Sabatier, Toulouse.
Lebeaupin Brossier, C., T. Arsouze, K. Béranger, M-N. Bouin, E. Bresson, V. Ducrocq, H. Giordani, M. Nuret, R.
Rainaud, I. Taupier-Letage, 2014: Ocean mixed layer responses to intense meteorological events during HyMeXSOP1 from a high-resolution ocean simulation. Ocean Modelling, 84, 84-103.
Madec , G., 2008: NEMO ocean engine, Note du pole de modélisation, Institut Pierre Simon Laplace (IPSL), France,
N° 27 ISSN N° 1288-1619.
Oost, W. A., G. J. Komen, C. M. K. Jacobs, C. Van Oort, 2002: new evidence for a relation between wind stress and
wave age from measurement during ASGAMAGE. Bound. Lay. Meteorol., 103 (3), 409-438.
Rainaud, R., 2015: Modélisation couplée océan-atmosphère pour l’étude des évènements météorologiques intenses en
Méditerranée occidentale. PhD. Thesis, Univ. P. Sabatier, Toulouse.
Seity, Y., P. Brousseau, S. Malardel, G. Hello, P. Bénard, F. Bouttier, C. Lac, V. Masson, 2011 : The AROME-France
convective scale operational model. Mon. Wea. Rev., 139, 976-991.
Thévenot, O., M-N. Bouin, V. Ducrocq, C. Lebeaupin Brossier, O. Nuissier, J. Pianezze, F. Duffourg, 2015 : Influence
of the sea state on Mediterranean heavy precipitation: a case study from HyMeX SOP1. Quart. J. Roy. Meteorol.
Soc., doi :10.1002/qj.2660.
Vincendon, B., 2010 : Apport des modèles météorologiques de résolution kilométrique pour la prévision des crues
rapides méditerranéennes : vers une prévision d'ensemble des débits en région Cévennes-Vivarais, PhD. Thesis,
Univ. P. Sabatier, Toulouse.