[MITgcm-support] single v. multiple processor

[Ian G. Fenty]

Hello,
Can somebody suggest any reasons why output from a single processor gcm 
compilation would differ from the output from a multiple processor 
compilation?  I'm getting differences of order 0.05 degrees after about 
15 weeks.  Here is my "data" file. 

 &PARM01
 tRef= 24.0 , 23.0 , 22.0 , 21.0 , 20.0 ,
       19.0 , 18.0 , 17.0 , 16.0 , 15.0 ,
       14.0 , 13.0 , 12.0 , 11.0 , 10.0 ,
        9.0 ,  8.0 ,  7.0 ,  6.0,   5.0 ,
        4.0 ,  3.0 ,  2.0 ,
 sRef= 35.65, 35.65 ,35.65, 35.65, 35.65,
       35.65, 35.65 ,35.65, 35.65, 35.65,
       35.65, 35.65 ,35.65, 35.65, 35.65,
       35.65, 35.65 ,35.65, 35.65, 35.65,
       35.65, 35.65 ,35.65,
 no_slip_sides=.false.,
 no_slip_bottom=.true.,
 viscAz =1.E-3,
 viscA4Grid = 0.10,
 viscAHGrid = 0.10,
 diffKhT=5.E1,
 diffKzT=1.E-5,
 diffKhS=5.E1 ,
 diffKzS=1.E-5,
 tempAdvScheme=30,
 saltAdvScheme=30,
 inADExact=.true.,
 StaggerTimeStep=.true.,
 allowFreezing=.false.,
 multiDimAdvection=.false.
 beta=1.E-11,
 tAlpha=2.E-4,
 sBeta =7.4E-4,
 gravity=9.81,
 gBaro=9.81,
 rigidLid=.FALSE.,
 implicitFreeSurface=.true.,
 eosType='JMD95Z',
 readBinaryPrec=32,
 writeBinaryPrec=32,
 tempStepping=.TRUE.,
 momStepping=.true.,
 saltStepping=.TRUE.,
 
 implicitDiffusion=.true.,
 implicitViscosity=.true.,
 globalFiles=.FALSE.,
 useSingleCpuIO=.true.,
 useCDscheme=.FALSE.,
 exactConserv=.true.,

 debugLevel=0,
 vectorInvariantMomentum=.TRUE.,
 useRealFreshWaterFlux = .false.,
 /
 &PARM02
 cg2dMaxIters=15000,
 cg2dTargetResidual=1.E-20,
 /
 &PARM03
 cAdjFreq = -1,
 nIter0 = 0,
 nTimeSteps = 8784,
 forcing_In_AB = .FALSE.,
 
 deltaTmom  =  3600.0,
 deltaTtracer= 3600.0,
 deltaTClock = 3600.0,
 abEps=0.1,
/
 &PARM04
 usingCartesianGrid=.FALSE.,
 usingSphericalPolarGrid=.FALSE.,
 usingCurvilinearGrid=.TRUE.,
 delZ=10.,10.,15.,20.,20.,25.,35.,50.,75.,100.,150.,200.,275.,350.,415.,450.,500.,500.,500.,500.,500.,500.,500.,
 &
/
 &PARM05
bathyFile='ib_open_40.bin',
hydrogSaltFile  =   'salt_init.ecco_19920901T060000_19920817T000000',
hydrogThetaFile = ' theta_init.ecco_19920901T060000_19920817T000000',
 /