Black Sea Dynamics Joanna Staneva • Click to edit Master text styles – Second level • Third level in cooperation w ith: – Fourth level E. Stanev » Fifth level D. Dietrich, M. Bow m an, K. Buesseler, H. Livingston, J. Murrey, J. Bullister, V. Kourafallou ( USA) C. Lancelot, J.-M. Beckers, M. Gregoire ( Belgium ) , T. Oguz ( Turkey) , K. Schrum ( Norw ay) , K. Tsiaras ( Greece) A. Stips ( JRC) , M. Vichi, ( I taly) V. Roussenov, E. Peneva ( Bulgaria) .... and others ... International Workshop for Numerical Ocean Modeling and Prediction Taipei, Taiwan, 23-25 April, 2008. 1
OUTLINE • Introduction • Click to edit Master text styles – The Black Sea – Models used – Second level • Results • Third level – Simulation of processes – Circulation – Fourth level – Water mass formation » Fifth level • Coupled physical-biogeochemical modelling • Conclusions 2
The Black Sea is an estuarine basin The total freshwater supply of 3 x 10 2 km 3 /year is large compared to the basin volume (~ 5.4 x 10 5 km 3 ) Unique water properties are due to small exchange in the straits. • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 3
The Black Sea is where most kinds of numerical models based on primitive • Click to edit Master text styles equations have been used to simulate circulation – Second level • Third level – Fourth level » Fifth level Atmospheric model Ocean models 4
Ocean models Ocean regimes and vertical coordinates • Click to edit Master text styles – Second level MOM DieCAST • Third level HOPS NLOM POP MICOM – Fourth level NCOM 1 HIM » Fifth level OPYC HYCOM (z+ σ + ρ ) H ∞ POM GHER POLCOMS 5 GETM, ROMS, TOMS, NCOM 2 , OPA, z+ σ
Black Sea DieCAST (5 nm horizontal resolution), low friction model Mechanisms of Black Sea circulation Sevastopol Danub Crimea e • Click to edit Master text styles Caucasus Kaliakr Western Gyre Ea stern Gyre a – Second level • Third level Synop Bospho Kizilirmak Sakaryia Batumi – Fourth level rus » Fifth level -10 -8 -6 -4 -2 0 2 4 6 8 10 12 (cm) Seasonal amplitudes: ~ 10 cm Staneva et al. (2001, JMS) Amplitudes of interannual variations: ~ 5 cm. 6
Specific questions answered by numerical models Deflection of Rim Current and entrainment of coastal water into the open sea • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level The transition between summer and winter circulation is controlled by baroclinic eddies. The large seasonal stratification cycle above a relatively shallow and strong pycnocline shapes the seasonal cycle of potential vorticity. 7 Staneva et al. (2001, JMS)
DieCAST Results T/ P data: basin Rossby Sea level Anomaly waves • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 8 Staneva et al. (2001, JMS)
CIW formation in the Black Sea • Click to edit Master text styles • General characteristics • Open questions – Second level • Mixing basin • Regions of formation • Third level • Fresh water • Rates of formation – Fourth level flux~300km 3 yr -1 » Fifth level • Temporal and spatial • Two-layer exchange in patterns straits • Transport of CIW • Limited vertical • No winter data exchange-the necessary condition of CIW mass formation 9
Black Sea MOM (5 nm resolution) The vertical circulation (~ 10 5 m 3 / s) is Below σ t = 15.5 stratification is entirely much weaker than dependent on salinity • Click to edit Master text styles horizontal circulation (~ 5 x 10 6 m 3 / s) and comparable with the amount of water entrained – Second level by the Mediterranean plume • Third level – Fourth level » Fifth level Stanev et al. (2003, JMR) 10
• Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 11
44.5N, 31E 42.5N, 32E • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 12
Decadal changes (Black Sea MOM, 5 nm resolution) • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level Model versus hydrographic survey data (no assimilation) 13 Stanev et al. (2003, JMR)
Coastal-Open ocean exchange: Black Sea MOM (5 nm resolution) )/ Δ t Convective heat flux: Q CF = r o C p (T a -T b Water mass w conv = Q CF / (r o C p T) formation controlled by • Click to edit Master text styles dynamics (topography) – Second level Replenishment • Third level time of CIL – Fourth level ~ 5 years Lee et al. (2002) » Fifth level 14 )
EBS-MOM-3 km Sea Surface Temperature 1991 1993 • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 15
EBS-MOM-3 km Temperature Vertical Sections (1991) • Click to edit Master text styles – Second level Zonal Section –February Meridional Section –February • Third level – Fourth level » Fifth level Zonal Section –August Meridional Section –August 16
Temperature (EBS-MOM-3 km) Time vs depth in box B • Click to edit Master text styles – Second level A B • Third level – Fourth level » Fifth level Time vs depth in box A 17
Temperature (EBS-MOM-3 km) • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 18
To conclude this part • Click to edit Master text styles The Black Sea provides optimal possibilities, – Second level using easily manageable models and • Third level observational data to address a wide spectrum – Fourth level of processes observed in the ocean. » Fifth level It is a useful test region for developing models, which can then be applied to larger scales. 19
Biogeochem ical m odelling Biogeochem ical m odelling ... to ... to address the functioning address the functioning of of the the ecosystem and and its response its response to to clim ate clim ate ecosystem • Click to edit Master text styles variabiliy and hum an and hum an forcing forcing variabiliy – Second level • Models: ERSEM, NPZD, BI OGEN • Third level • w ith different levels of com plexity – Fourth level » Fifth level and different resolution Determ ine: : process Determ ine process and and m echanism s m echanism s of m ass tranfer from m ass tranfer from land to land to ocean ocean of Validation: m odel sim ulations Validation: m odel sim ulations versus survey and satellite data survey and satellite data 20
WHY A MODEL CAN DO BETTER THAN CORRELATIONS BETWEEN EVENTS? • The synergy between the different human forcing cannot • Click to edit Master text styles be assessed from simple correlations between ecological – Second level observations and historical correlations. • Third level • Mechanistic models, which describe the kinetics between – Fourth level biological and chemical compartments as a function of » Fifth level meteorological and human forcings provide a powerful tool which encompasses this complexity. • The ecological model ERSEM is established in order to assess the response of the north-western Black Sea ecosystem to human-induced changes and predict its future evolution. 21
ERSEM • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 22
• Click to edit Master text styles Benthos model – Second level • Third level – Fourth level » Fifth level Pelagic model 23
OFF-LINE COUPLING BETWEEN MOM AND ERSEM • Atmospheric forcing – high frequency • Click to edit Master text styles atmospheric analyses data from ECMWF – Second level • River discharge – daily data taken from A. • Third level Cociasu – Fourth level • Open BC – Black Sea MOM » Fifth level • Initialization: Physical sub-model – MOM output Biogeochemical sub-model – ERSEM, observational data 24
Seasonal evolution of the vertical profiles of T and S • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 25
Model-data comparissons in 2003 • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level D • Reg. 4 1 2 4 3 26
Biogeochemical modelling (Satellite v/s Model Data) • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level 27
Vertical profiles - 2003 • Click to edit Master text styles – Second level • Third level – Fourth level » Fifth level Spring 28
Scenario simulations top-Danube discharge; bottom-model results. Black line 1984 (pre-eutrophication period); red • Click to edit Master text styles line- 1993 (high eutrophication) – Second level • Third level – Fourth level » Fifth level 29
Time evolution of some of the ecosystem variables • Click to edit Master text styles Black line 1984; red line 1993. – Second level • Third level – Fourth level » Fifth level 30
Scenaria: Evolution of the vertical profiles copepods [ mg.C m –3 ] diatoms [ mg.Chla. m –3 ] • Click to edit Master text styles – Second level 80s • Third level – Fourth level » Fifth level 90s 31
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