Onboard implementation of the GHER model for the Black Sea, with SST and CTD data assimilation

The first operational implementation of the GHER hydrodynamic model is described. It took place onboard the research vessel Alliance with all computation and sharing of forecasts being realised from the vessel in near-real time. The forecasts were realised in the context of the Turkish Straits System 2008 campaign, which aimed at the real-time characterisation of the Marmara Sea and (south-western) Black Sea. The model performed badly at first, mainly because of poor initial conditions. Hence, as the model includes a reduced-rank extended Kalman filter assimilation scheme, after a hindcast where sea surface temperature and temperature and salinity profiles were assimilated, the model yielded realistic forecasts. Furthermore, the time required to run a one-day simulation (about 300 seconds of simulation, or 500 with pre-processing and data transfers included) was very limited and thus operational use of the model is possible.

[1]  Allan R. Robinson,et al.  Real-time regional forecasting , 1996 .

[2]  Jacques Verron,et al.  A singular evolutive extended Kalman filter for data assimilation in oceanography , 1998 .

[3]  Jean-Marie Beckers,et al.  Modeling the nitrogen fluxes in the Black Sea using a 3D coupled hydrodynamical-biogeochemical model: transport versus biogeochemical processes, exchanges across the shelf break and comparison of the shelf and deep sea ecodynamics , 2004 .

[4]  E. Özsoy,et al.  Oceanography of the Black Sea: A review of some recent results , 1997 .

[5]  Wolfgang Ludwig,et al.  River discharges of water and nutrients to the Mediterranean and Black Sea: Major drivers for ecosystem changes during past and future decades? , 2009 .

[6]  J. Nihoul,et al.  Modelling the general circulation of shelf seas by 3Dk-ε models , 1989 .

[7]  Allan R. Robinson,et al.  An interdisciplinary ocean prediction system: Assimilation strategies ana structured data models , 1996 .

[8]  Jean-Marie Beckers,et al.  Seasonal temperature and salinity fields in the Mediterranean Sea: Climatological analyses of a historical data set , 1996 .

[9]  Jean-Marie Beckers,et al.  Modelling the Danube-influenced North-western continental shelf of the Black Sea. I: Hydrodynamical processes simulated by 3-D and box models , 2002 .

[10]  R. Rew,et al.  NetCDF-4 : Software Implementing an Enhanced Data Model for the Geosciences , 2007 .

[11]  Walter H. F. Smith,et al.  Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings , 1997 .

[12]  Pierre Brasseur,et al.  Assimilation of altimetric data in the mid-latitude oceans using the Singular Evolutive Extended Kalman filter with an eddy-resolving, primitive equation model , 1999 .

[13]  J. Beckers,et al.  Two-way nested model of mesoscale circulation features in the Ligurian Sea , 2005 .

[14]  Jean-Michel Brankart,et al.  Assimilation of sea-surface temperature and altimetric observations during 1992–1993 into an eddy permitting primitive equation model of the North Atlantic Ocean , 2003 .