[MITgcm-support] only eta as open boundary condition

[Chun-Yan Zhou]

Dear all, 
 I tried to provide Eta as open boundary condition for  a regional model. As the barotropic tide amplitude and phase along the open boundary can be obtained from sea charts,but the velocities along the boundary are not known. I tested a simple case with turning on OBCS=.True. and  nonlinFreeSurf=4, exactConserv=.TRUE., the OBEeta amplitude=1m. But the Eta turned out to be  
0.0000001 order except for the open boundary, it seems like the Eta at the boundary has nothing to do with inside domain. How to deal with such situation without prescribed velocity file at the boundary?  

data 
# ==================== 
# | Model parameters | 
# ==================== 
# 
# Continuous equation parameters 
 &PARM01 
 sRef=45*35., 
 viscA4=0.0E4, 
 viscAh=1.E2, 
 viscAz=1.E-4, 
 no_slip_sides=.FALSE., 
 no_slip_bottom=.TRUE., 
 diffK4T=0.E4, 
 diffKhT=1.E2, 
 diffKzT=1.E-4, 
 diffK4S=0.E4, 
 diffKhS=0.E-2, 
 diffKzS=0.E-5, 
 implicitDiffusion=.FALSE., 
 implicitViscosity=.FALSE., 
 f0=1.e-4, 
 beta=1.E-11, 
 eosType='LINEAR', 
 tAlpha=2.E-4, 
 gravity=9.81, 
 gBaro=9.81, 
 rigidLid=.FALSE., 
 tempStepping=.TRUE., 
 nonlinFreeSurf=4, 
 exactConserv=.TRUE., 
 hFacMin=0.05, 
 readBinaryPrec=64, 
#- not safe to use globalFiles in multi-processors runs 
#globalFiles=.TRUE., 
 staggerTimestep=.TRUE., 
 & 

# Elliptic solver parameters 
 &PARM02 
 cg2dMaxIters=300, 
 cg2dTargetResidual=1.E-13, 
 cg3dMaxIters=20, 
 cg3dTargetResidual=1.E-8, 
 & 

# Time stepping parameters 
 &PARM03 
 nIter0=0, 
 nTimeSteps=6000, 
#nTimeSteps=8640, 
 deltaT=22.357, 
 abEps=0.01, 
 pChkptFreq=44714., 
 chkptFreq=0.0, 
 dumpFreq=4471.4, 
#taveFreq=864000.0, 
 monitorSelect=2, 
 monitorFreq=1., 
 periodicExternalForcing=.TRUE., 
 externForcingPeriod=223.57, 
 externForcingCycle=44714., 
 & 

# Gridding parameters 
 &PARM04 
 usingCartesianGrid=.TRUE., 
 delX=120*4560., 
 delY=45*5555., 
 delZ=45*2., 
 & 
data.obcs 
# Open-boundaries 
 &OBCS_PARM01 
 OB_Ieast=45*-1, 
 useOBCSprescribe=.TRUE., 
 OBEetaFile = 'OBEeta.bin', 
 OBEtFile = 'OBEt.bin', 
 & 


# Input datasets 
 &PARM05 
 bathyFile='topog.slope', 
 hydrogThetaFile='T.init', 
 & 
Chunyan Zhou
Division of Civil Engineering
School of Engineering, Physics and Mathematics
College of Art, Science and Engineering
G19,Fulton Building
University of Dundee
Dundee DD1 4HN
Tel: +44 (0) 1382 385431




The University of Dundee is a registered Scottish charity, No: SC015096
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