[MITgcm-support] how to change the vertical mixing strength

[979583702]

Hi everyone,


Recently, I'd like to study the relationship between MOC and ocean vertical mixing. I want to change the strength of vertical mixing, as far as I know, we can change the two parameters:  diffKrT and  diffKrS (the value typically ranges from 1.E-5 to 1.E-4) in the data file. In my experiments, I changed diffKrT and  diffKrS from 1.E-5 to 5.E-5, but I found there is little change in the MOC strength. It seems quite odd.


In addition, I didn't switch on the KPP package in the data.pkg. (I comment out the line #useKPP = .TRUE. in data.pkg)


I was wondering if anyone could tell me the reason why MOC changes little when I change the  diffKrT and  diffKrS.  Is there any better way to change the vertical mixing strength (e.g., switch on KPP package and change the vertical mixing strength)?  If there is, how to change?


Thank you so much.


Best,


Fei






Here is my data file:
# ====================
# | Model parameters |
# ====================
#
# Continuous equation parameters
 &PARM01
 tRef               = 3*23.,3*22.,21.,2*20.,19.,2*18.,17.,2*16.,15.,14.,13.,
                      12.,11.,2*9.,8.,7.,2*6.,2*5.,3*4.,3*3.,4*2.,12*1.,
 sRef               = 50*34.5,
 no_slip_sides  = .TRUE.,
 no_slip_bottom = .TRUE.,
#
 viscAr=0.5E-4,
#
 viscAh=1.E0,
 viscAhGrid=2.E-2,
# viscAh=2.0e4,
#
 diffKhT=1.E1,
 diffKhS=1.E1,
# change the vertical mixing parameters from 1.E-5 to 5.E-5
 diffKrT=1.E-5,
 diffKrS=1.E-5,
#
### diffKrBL79surf=0.1E-4,
### diffKrBL79deep=1.0E-4,
 bottomDragQuadratic = 0.001,
#when using ggl90
 ivdc_kappa=10.,
 implicitDiffusion=.TRUE.,
 implicitViscosity=.TRUE.,
 useRealFreshWaterFlux=.TRUE.,
# balanceThetaClimRelax=.TRUE.,
 balanceSaltClimRelax=.TRUE.,
# balanceEmPmR=.TRUE.,
# balanceQnet=.TRUE.,
 allowFreezing=.FALSE.,
### hFacInf=0.2,
### hFacSup=2.0,
 hFacMin=.2,
 hFacMinDr=5.,
 select_rStar=2,
 nonlinFreeSurf=4,
 gravity=9.81,
 rhonil=1029.,
 rhoConst=1029.,
 rhoConstFresh=1000.,
 convertFW2Salt=-1.,
 eosType='JMD95Z',
 implicitFreeSurface=.TRUE.,
 exactConserv=.TRUE.,
 useSingleCpuIO=.TRUE.,
 tempAdvScheme=30,
 saltAdvScheme=30,
 tempVertAdvScheme=3,
 saltVertAdvScheme=3,
 tempImplVertAdv=.TRUE.,
 saltImplVertAdv=.TRUE.,
 staggerTimeStep=.TRUE.,
 vectorInvariantMomentum=.TRUE.,
#when using the cd scheme:
# useCDscheme=.TRUE.,
 useJamartWetPoints=.TRUE.,
 readBinaryPrec=32,
 writeBinaryPrec=32,
 debugLevel=1,
 /


# Elliptic solver parameters
 &PARM02
 cg2dMaxIters=300,
#cg2dTargetResWunit=1.E-12,
 /


# Time stepping parameters
 &PARM03
 nIter0=0,
#2 lev2 for testing:
#nTimeSteps=8,
 nTimeSteps=350000,
#
 forcing_In_AB=.FALSE.,
 momDissip_In_AB=.FALSE.,
#when using the cd scheme:
# epsAB_CD = 0.25,
# tauCD=172800.0,
 deltaTmom   =3600.,
 deltaTtracer=3600.,
 deltaTfreesurf=3600.,
 deltaTClock =3600.,
#when using ab2:
# abEps = 0.1,
#when using ab3:
 doAB_onGtGs=.FALSE.,
 alph_AB=0.5,
 beta_AB=0.281105,
#
 pChkptFreq  =10368000.0,
 chkptFreq   =10368000.0,
# taveFreq    =2635200.0,
# dumpFreq    =2635200.0,
# monitorFreq = 7200.0,
 monitorFreq = 2592000.0,
 dumpInitAndLast = .TRUE.,
 adjDumpFreq = 31536000.0,
#adjDumpFreq = 604800.0,
 adjMonitorFreq = 864000.0,
 pickupStrictlyMatch=.FALSE.,
 /


# Gridding parameters
 &PARM04
 usingCurvilinearGrid=.TRUE.,
 delR = 
     10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.01,
     10.03, 10.11, 10.32, 10.80, 11.76, 13.42, 16.04, 19.82, 24.85,
     31.10, 38.42, 46.50, 55.00, 63.50, 71.58, 78.90, 85.15, 90.18,
     93.96, 96.58, 98.25, 99.25,100.01,101.33,104.56,111.33,122.83,
     139.09,158.94,180.83,203.55,226.50,249.50,272.50,295.50,318.50,
     341.50,364.50,387.50,410.50,433.50,456.50,
 /


# Input datasets
 &PARM05
 diffKrFile='total_diffkr_r009bit11.bin',
 adTapeDir='tapes',
#bathyFile      ='bathy_eccollc_90x50.bin',
 bathyFile      ='bathy_eccollc_90x50_min2pts.bin',
 hydrogThetaFile='T_OWPv1_M_eccollc_90x50.bin',
 hydrogSaltFile ='S_OWPv1_M_eccollc_90x50.bin',
 viscA4Dfile    ='fenty_biharmonic_visc_v11.bin',
 viscA4Zfile    ='fenty_biharmonic_visc_v11.bin',
 geothermalFile='geothermalFlux.bin',
#
 /
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