Application of FVCOM to the Gulf of Maine/Georges Bank:
Simulated and Assimilated Modeling Studies of Stratification and Sub-tidal Circulation
Chen, C, H. Liu, R. C. Beardsley, G. Cowles, J. Pringle, R. Schlitz and B. Rothschild
The FVCOM GOM/GB
Physical Model
Wind stress, heat flux
GOM/GB MM5
• Real-time tidal forcing
• River discharges
• Scotian shelf water input
• North Atlantic open boundary condition ??
• SST
• Hydrographic survey CTD
• ADCP
• Moored current meter data
• CODAR??
Assimilation Boundary forcings
Meteorological forcing
: H, , , D, s, , q2, q2l, Am, Kh I : u, v,
The Finite-Volume Coastal Ocean Model (FVCOM)
6 ADCPs 3-6, 1999
NECE
The 1995 and 1999 Experiments
1. Run the model with tidal forcing only from December 1-15;
2. Re-start the model on December 15 with the initial condition of T and S given by December climatologic hydrographic field;
3. Add real-time wind stress, heat flux, river discharge, etc on January 1
Simulating
Assimilating: SST, Current
Re-start with the assimilated field
January February
Observed Calculated CalculatedObserved
M2
N2
S2
Observed ObservedCalculated Calculated
K1
O1
The 1995 Simulation and Assimilation
Jan
Feb
March
Observed Simulated Assimilated
SimulatedObserved Assimilated
April
May
June
Observed Simulated Assimilated
July
Aug
Sept
Observed Simulated Assimilated
Oct
Nov
Dec
23 m
99 m
191 m
Site: NECE
Site: NECE
23 m
99 m
191 m
February 1995
July 1995
The 1999 Summer Simulation and Assimilation
Observed Simulated Assimilated
Times (day) May 1999
Observed Simulated Assimilated
Ob
serv
edS
imu
late
dA
ssim
ilat
ion
Site2 Site4 Site6
Comparison between observed and simulated currents at an ADCP site
May 1999
May 1999Simulated subtidal surface water temperature and currents
Summary
1. Both simulation and assimilation clearly show that the seasonal variation of clockwise subtidal gyre on GB and also cyclonic circulation around the Jordon basin. The cyclonic circulation forming around the Jordon basin could cause a significant on-bank water transport to GB during summer.
2. Good agreement between model-predicted and observed currents was found on the southern flank of GB, but not in the Northeast Channel (NEC). This suggests that the subtidal circulation on GB is mainly controlled by local forcing, while the currents in the eastern GOM/GB are strongly influenced by water input from the Scotian Shelf.
3. Nudging assimilation is used to merge the model-computed and observed currents in the NEC. This approach produces a more realistic pattern of subtidal currents and on-bank transport on the northeastern flank of GB.