ED 173 - SDU2E
Nom du laboratoire
(et n° de l’unité) dans lequel se déroulera la thèse :
LEGOS UMR 5566
Titre du sujet proposé : Fonctionnement et variabilité de l’upwelling de Nha Trang : altimétrie et modélisation régionale
Financement :
 acquis ( préciser nom de l’organisme)  mis au concours ( contrat doctoral ministériel)
X candidature auprès d’un organisme ( préciser nom de l’organisme) : cofinancement USTH (Vietnam) + demandes IRD et Région MIP
Spécialités de l’école doctorale :
(cocher une seule spécialité sans la modifier)
 Astrophysique, Sciences de l’Espace, Planétologie
X Climat, Océan, Atmosphère, Surfaces Continentales
 Ecologie Fonctionnelle
 Hydrologie, Hydrochimie, Sol, Environnement
 Sciences de la Terre et des Planètes solides
Nom et statut (PR, DR, MCf, CR, …) du (des) responsable (s) de thèse (préciser si HDR) :
Marine Herrmann, CR IRD ; Rosemary Morrow, CNAP HDR
Coordonnées (téléphone et e-mail) du (des) responsable(s) de thèse : marine.herrmann@legos.obs-mip.fr
0561333056
Résumé du sujet de la thèse (le descriptif ne doit pas dépasser une page recto/verso)
Costal oceanic regions often show high primary production associated to large nutrients inputs. This biological activity conditions the functioning of marine ecosystems hence influences local biodiversity and halieutic resources. It also impacts global climate by participating in oceanic carbon sequestration. Spatial and temporal heterogeneity of nutrients concentration is partly due to water masses transport and mixing : oceanic dynamics play a major role in the functioning and variability of marine ecosystems. Coastal oceanic regions are moreover submitted to a strong human stress, and their response to climate variations is an open question.
The PhD subject proposed here will participate to improve the understanding of the functioning and variability of marine coastal dynamics and ecosystems, and to assess their response to anthropic influence and climate variations. For that the thesis will focus on the
Nha Trang upwelling, a major process of the coastal and regional marine circulations and ecosystems in the East Sea. By uplifting deep nutrient rich water masses up to the surface photic layer in summer, this upwelling induces a strong biological activity that influences the
Vietnamese halieutic resources. It thus plays a major role in the Vietnamese halieutic industry. The PhD thesis will adopt a multidisciplinary integrated approach combining coupled physical-biogeochemical numerical modeling, multi-sensors spatial observations and in-situ data to answer to the following questions:

ED 173 - SDU2E
- What is the hydrodynamic functioning of the Nha Trang upwelling ? Which physical processes interven e (tide, (sub)mesoscale structures, vertical mixing…), which water masses are involved, which factors trigger or weaken it (topography, large scale oceanic circulation, atmospheric forcing, hydrological forcing) ?
- How does it influence the marine pelagic planktonic ecosystem that constitutes the first trophic levels of the food chain ? In particular how does it participate to matter, nutrients and planktonic ecosystem components transport and mixing? How does it influence the associated carbon cycle associated (carbon dioxide absorption and respiration, deep organic carbon export) ?
- What are the variability scales of the upwelling dynamics, which factors trigger them, and how is this variability transmitted to the planktonic pelagic ecosystem ?
- How will the dynamics and the ecosystem be impacted by climate change (end of XXIst century) ?
The PhD candidate should have a master in ocean sciences and some knowledge in numerical modelling and data processing.