[MITgcm-support] temperature difference in the horizontal direction cause large velocity

[Chun-Yan Zhou]

The temperature difference in horizontal direction are 2º and the
velocity there is 0 

Dear all, 
  
 Again, I test about the different temperature distribution. The
topography is a slope with deepest 90m. No other forces are applied. 
The first case, the temperature decreased with only depth linearly. 
The second case, the temperature has a difference 2º  in the horizontal
direction, and still decreased with depth. 


In first case, the velocity is almost zeros and surface elevation Eta
is also zero, which quite make sense. 


The second case, however,  the velocity can reach up to 0.2m/s where
the temperature change very quickly in the horizontal direction. It also
cause surface elevation eta around 0.01m.  
  
Why does the temperature difference in the horizontal direction cause
such large velocity and Eta? 
Thanks in advance 


The data file 

# ==================== 
# | Model parameters | 
# ==================== 
# 
# Continuous equation parameters 
 &PARM01 
 sRef=60*35., 
 viscA4=0.0E4, 
 viscAh=1.E-3, 
 viscAz=1.E-5, 
 no_slip_sides=.FALSE., 
 no_slip_bottom=.FALSE., 
 diffK4T=0.E4, 
 diffKhT=1.E-3, 
 diffKzT=1.E-5, 
 diffK4S=0.E4, 
 diffKhS=0.E-2, 
 diffKzS=0.E-5, 
 implicitDiffusion=.TRUE., 
 implicitViscosity=.TRUE., 
 f0=0.e-4, 
 beta=0.E-11, 
 eosType='LINEAR', 
 tAlpha=2.E-4, 
 sBeta =0.E-4, 
 gravity=9.81, 
 gBaro=9.81, 
 rigidLid=.FALSE., 
 saltStepping=.FALSE., 
 implicitFreeSurface=.TRUE., 
 hFacMin=0.05, 
 nonHydrostatic=.TRUE., 
 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=80000, 
 nTimeSteps=80000, 
#nTimeSteps=8640, 
 deltaT=22.357, 
 abEps=0.01, 
 pChkptFreq=447140., 
 chkptFreq=0.0, 
 dumpFreq=223570, 
#taveFreq=864000.0, 
 monitorSelect=2, 
 monitorFreq=1., 
 periodicExternalForcing=.TRUE., 
 externForcingPeriod=223.57, 
 externForcingCycle=44714., 
 & 

# Gridding parameters 
 &PARM04 
 usingCartesianGrid=.TRUE., 
 delX=700*500., 
 dYspacing=50000., 
 delZ=60*1.5, 
 & 

# 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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