[MITgcm-support] flux boundary condition

[Olivier Arzel]

Hello all,
I am running an experiment under constant flux boundary conditions for 
temperature and salinity.
While I have a zero net surface heat flux in average, there is a trend 
in the global average ocean temperature.
I must have missed something obvious here but I cannot figure it out.
Attached are the data file and the timeseries of the statistics that 
show zero FORCING_QNET_MEAN and a temperature trend in DYNSTAT_THETA_MEAN.
To reach zero average surface heat flux, here is what I did using matlab:
areasum=sum(sum(grid_ocn.HFacC(:,:,1).*grid_ocn.rA));
varmean=sum(sum(shf_rtrs.*grid_ocn.HFacC(:,:,1).*grid_ocn.rA))/areasum;
shf_rtrs=shf_rtrs-varmean*grid_ocn.HFacC(:,:,1);
% mean shf_rtrs is zero
I did the same for salinity forcing, and observe no salinity trend, 
perhaps due to the fact that I use exactConserv=.TRUE. ?
Any help would be much appreciated
Thanks !
Olivier


-- 
-----------------------------------
Olivier Arzel
Laboratoire de Physique des Océans
Université de Bretagne Occidentale
6 Avenue le Gorgeu / CS 93837
29238 Brest cedex 3
France
Tel: +33 (0)2 98 01 62 25
Fax: +33 (0)2 98 01 64 68
homepage : http://stockage.univ-brest.fr/~oarzel/
homepage : http://web.maths.unsw.edu.au/~oarzel/

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# ====================
# | Model parameters |
# ====================
#
# Continuous equation parameters
 &PARM01
 tRef = 32*4.,
 sRef = 32*35.,
 viscAr=1.E-3,
 viscAh=1.E5,
 diffKhT=0.,
 diffKrT=1.E-4,
 diffKhS=0.,
 diffKrS=1.E-4,
 rhonil=1035.,
 rhoConstFresh=1000.,
 tAlpha=2.E-4,
 sBeta =8.E-4,
 eosType = 'LINEAR',
 ivdc_kappa=100.,
 implicitDiffusion=.TRUE.,
 allowFreezing=.TRUE.,
 exactConserv=.TRUE.,
 useRealFreshWaterFlux=.TRUE.,
 useCDscheme=.TRUE.,
# turn on looped cells
 hFacMin=.05,
 hFacMindr=50.,
# set precision of data files
 readBinaryPrec=64,
 &

# Elliptic solver parameters
 &PARM02
 cg2dMaxIters=500,
 cg2dTargetResidual=1.E-13,
 &

# Time stepping parameters
 &PARM03
# nIter0=       0,
# nTimeSteps = 20,
 startTime =          0.,
 endTime   = 155520000000,
 deltaTmom = 300.,
 tauCD =     321428.,
 deltaTtracer= 86400.,
 deltaTClock = 86400.,
 deltaTfreesurf= 86400.,
 abEps = 0.1,
 pChkptFreq= 31104000000.,
 dumpFreq=   3110400000.,
 taveFreq=   3110400000.,
 monitorFreq=31104000.,
# 2 months restoring timescale for temperature
# tauThetaClimRelax=  5184000.,
# 6 months restoring timescale for salinity
# tauSaltClimRelax = 15552000.,
# periodicExternalForcing=.FALSE.,
# externForcingPeriod=2592000.,
# externForcingCycle=31104000.,
 &

# Gridding parameters
 &PARM04
 usingSphericalPolarGrid=.TRUE.,
 delR= 15., 32., 41., 50., 59., 68., 77., 86.,
       95., 104., 113., 122., 131., 140., 149., 158.,
       167., 176., 185., 194., 203., 212., 221., 230.,
       239., 248., 257., 266., 275., 285., 296., 306.,
 ygOrigin=-70.,
 dySpacing=1.,
 dxSpacing=1.,
 &

# Input datasets
 &PARM05
 bathyFile=      'bathymetry.bin',
 hydrogThetaFile=,
 hydrogSaltFile= ,
 zonalWindFile=  'windx.bin',
 meridWindFile=  ,
 thetaClimFile=  ,
 saltClimFile=   ,
 surfQnetFile=   'shf_rtrs.bin',
 the_run_name=   'idealized_atl',
# fresh water flux is turned on, comment next line to it turn off
# (maybe better with surface salinity restoring)
 EmPmRFile=      'emp_rtrs.bin',
 &
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