THE BC SHELF ROMS MODEL THE BC SHELF ROMS MODEL Diane Masson, Isaak Fain, Mike Foreman Institute of Ocean Sciences Fisheries and Oceans, Canada The Canadian perspective AVISO EKE (cm 2 s -2 )

2 Motivation For the last several years, DFO has provided support for the development of a BC shelf ocean model to address departmental issues on:  Process oriented studies  Regional climate impact  Coupling with biological model  OBCs for smaller regional grids (e.g. Strait of Georgia/Juan de Fuca Strait)

  Model domain from south of Columbia River to the Alaska border   3km (236 X 410), 30 sigma levels   Forcing: tides, 3 hourly wind and daily atmospheric forcing (bulk_fluxes) from NARR, monthly discharge from main rivers, climatological open boundary forcing (Levitus)   Now running on new HP 256 cpu machine i.e. decadal runs feasible ( ) Model Setup Depth (m)

ClimatologyROMS ( ) Winter Summer Over an annual cycle, the model behaves realistically: Thermal Stratification (including summer upwelling) SST (ºC)

June December Reversal of shelf break current (northward in winter, southward in summer)

6 Estuarine circulation in Juan de Fuca Strait Juan de Fuca Strait Haro Strait Strait of Georgia Observed- Summer ROMS - Summer Salinity

7 Salish Sea grid  1 km horizontal resolution (184x370)  31 sigma vertical levels  8 tidal constituents  Freshwater daily discharge from 7 rivers (and temp)  Seasonal T/S profiles along OBCs  Hourly wind forcing from observations  Monthly atmospheric forcing (heat flux) from observations  Coupled with NPZD model (Angelica Pena)

8 Sub-surface intrusions in the Strait of Georgia (2007) ROMS Depth (m) Observed

Interannual variability: ROMS able to capture main features, e.g. annual summer SST anomalies ROMSAVHRR Pathfinder v ( o C)

Fraser River projections: Morrison et al., J. Hydrology, Tidal forcing unchanged 2.Wind & heat flux thru interpolation from GCMs and/or RCMs 3.Oceanic initial conditions & boundary forcing from ocean component of GCMs component of GCMs 4.Freshwater runoff by downscaling precipitation & temperature from RCMs Climate impact: Development of a Regional Climate model

Climate impact: future changes in oceanic salinities & temperatures  Lateral boundary & initial 3D salinity & temperature fields for future simulations will (probably) be anomalies added to present-day climatologies  Anomalies computed from CCCma CGCM3.1 T47 SRES A2 run #4 -- Averages over shelf model domain  BC waters are becoming fresher & warmer

12 Future model development   Improve OBCs (e.g. NCOM) to examine effect of local vs remote forcing on coastal circulation)   Continue model validation (e.g. satellite EKE, long term moorings)   Track passive tracer (e.g. northern reach of CUC)   Climate impact study (downscaling of atm. forcing)   Biological applications (e.g. HABs in Juan de Fuca eddy (PNWTOX), fish larvae drift in Strait of Georgia)   Extend run beyond (e.g. to examine ocean conditions during period of Fraser River sockeye fisheries dramatic ups and downs, to start before 2007)