The Nha Trang upwelling
The Nha Trang upwelling, or South Central Vietnam upwelling, is one of the key processes of the South China circulation. This upwelling occurs in summer under the influence of the winds associated to the southwest monsoon. Through its action on the transport and mixing of water masses, it influences the nutrients distribution and therefore the functioning of the coastal marine ecosystems in this region.
Questions associated to this process are the following.
- What are the physical processes that govern its functionning ?
- What are the atmospheric and oceanic factors responsible for its variability at different scales (from the daily intense event to the interannual variability and long term evolution) ?
- How does it influence the marine ecosystems, and in particular how does it transmit its variability ?
The study of the Nha Trang upwelling gather members of French (LEGOS IRD, EIO for biogeochemistry measurements, CNRM-Météo-France for atmospheric measurements and LOG for optical measurements) and Vietnamese (VNIO, HMO at VNU-HUS) research centers. The VNIO has a long experience of the observation and study of the Nha Trang upwelling. In particular, between 2003 and 2005, this group conducted several in-situ observations campaigns to monitor the upwelling. Water masses hydrologic characteristics, currents and biogeochemical parameters were measured. HMO is strongly involved in hydrodynamical modeling and in-situ observation campaigns. LEGOS develops and uses numerical modelling tools (hydrodynamics model coupled with atmosphere/biogeochemical or sediment transport models). These tools are used in order to perform multi-annual high resolution simulations of the East Sea circulation and influence, with a particular focus on the Nha Trang upwelling. LEGOS is also supervising the oceanographic campaign DRAGUN, specially dedicated to the study of the hydrodynamics and biogeochemistry in the Nha Trang region.
The study of the Nha Trang upwelling is the subject of a PhD thesis funded by USTH (N.D. Da) and supervised by researchers from LEGOS and VNU-HUS : N. D. Da, presently funded by CNES (TOSCA MONSUN) uses jointly satellite altimetry data, in-situ data that will be obtained during the DRAGUN campaign (July 2014) and numerical modeling.
SST in summer 1999 in a simulation of the South China Sea circulation between 1990 and 2000 (ROMS, 1/12°). The signature of the Nha Trang upwelling associated to a cold water tongue near 11°N is clearly visible.
LEGOS M. Herrmann, F. Birol, F. Nino, R. Morrow , Nguyen Dac Da
LOG, Wimereux - H. Loisel, X. Mériaux
CNRM, Brest - M.-N. Bouin
UMR EIO, Papeete - M. Rodier
Center of research for Environmental Fluid Dynamics et Faculty of Hydrology, Meteorology and Oceanography, Hanoi University of Science (HUS-VNU), Hanoi - Nguyen Minh Huan
National Institute of Oceanography (NIO), VAST, Nha Trang - Bui Hong Long, Le Dinh Mau
University of Science and Technology of Hanoi (USTH), Hanoi - Nguyen Nguyet Minh, Trin Bich Ngoc
MONSUN (TOSCA, CNES - 2014-17), DRAGUN (LEFE-INSU - 2014), HILO (Amb. France / MAE, 2014-15)
USTH fellowship for Nguyen Dac Da (2014-17) UMR LEGOS/IRD