[MITgcm-support] Negative Salinities

[Sergio Jaramillo]

Hi Martin,

Thanks a lot for your comments. I noticed that the CPP-flag does not 
improve anything for me. The problem does occur after the first time 
step, but I wouldn't think that it has anything to do with my forcing 
fields as I haven't changed this from my old runs, and I don't use any 
salinity filed as an input. I force the model with a body force that I 
wrote into external_forcing.F. I will put here part of my data file in 
case anyone sees something wrong and could give me any advice:

# ====================
# | Model parameters |
# ====================
#
# Continuous equation parameters
 &PARM01

 Tref =  14.1283,  11.9377,  9.89651,    8.154,  6.71021,  
          5.6647,  4.91792,  4.32048,  3.72305,  3.02605, 
          2.32905,   1.7814,  1.18397, 0.486969, -0.110463,
         -0.558536,  -1.0564, -1.70361, -2.35083, -2.84869,
         -3.29676, -3.69505, -4.19291, -4.69077, -5.18863,
         -5.58691,  -5.9852, -6.28392,  -6.6822, -7.18006, 
         -7.92685, -8.92257,
 sRef= 32*35.,
 viscAz=1.E-6,
 viscAh=1.E-6,
 no_slip_sides=.TRUE.,
 no_slip_bottom=.TRUE.,
 bottomDragLinear=0.,
 viscA4=0.E12,
 diffKhT=1.E-6,
 diffKzT=1.5E-9,
 diffKhS=1.E-6,
 diffKzS=1.5E-9,
 tempAdvScheme= 33,
 saltAdvScheme= 33,
 saltForcing= .FALSE.,
 tempForcing=.FALSE.,
 staggerTimeStep=.TRUE.,
 exactConserv=.TRUE.,
 f0=0.52,
 beta=0.E-11,
 tAlpha=2.E-3,
 rhonil=1.0043E3,
 sBeta =0.E-4,
 gravity=9.81,
 gBaro=9.81,
 rigidLid=.FALSE.,
 implicitFreeSurface=.TRUE.,
 eosType='LINEAR',
 hFacMin=0.2,
 nonHydrostatic=.FALSE.,
 readBinaryPrec=64,
 globalFiles=.FALSE.,
 vectorInvariantMomentum=.FALSE.,
 &


Sergio Jaramillo
UBC

>
>Sergio,
>
>no use in defining this CPP-flag, it will not solve your problem. This 
>routine raises a flag/warning, if it finds one or more negative 
>salinity values in the current horizontal slab and resets the negative 
>values to zero.
>But if you have salinities of +/-1.5e+139, your problem is likely to be 
>something completely different. If this happens after one or two time 
>steps, I am guessing, that there are some memory issues, such as a 
>double precision field is read into a single precision variable or vice 
>versa (for example, your forcing fields).
>
>Martin
>
>On Saturday, May 22, 2004, at 02:47 AM, Sergio Jaramillo wrote:
>
>  
>
>>Dear MITgcm support,
>>
>>I just noticed that the salinity field that I get from my runs is 
>>going negative like -1.5e+139!. Why could this be? I only input 
>>sRef=32*35, and I do all the stratification using the temperature 
>>profile. I also have set sBeta=0.  Also I didn't have this problem 
>>before , when I used an older version of the model (like a year ago, 
>>v1.15 according to find_rho.F ).
>>
>>Finally I find this in find_rho.F:
>>
>>#ifdef CHECK_SALINITY_FOR_NEGATIVE_VALUES
>>     CALL LOOK_FOR_NEG_SALINITY( bi, bj, iMin, iMax, jMin, jMax,  k,
>>    &     sFld, myThid )
>>#endif
>>
>>Should I define this in CPP_OPTIONS.h?
>>
>>
>>Thanks a lot,
>>
>>Sergio Jaramillo
>>UBC
>>
>>_______________________________________________
>>MITgcm-support mailing list
>>MITgcm-support at mitgcm.org
>>http://dev.mitgcm.org/mailman/listinfo/mitgcm-support
>>
>>    
>>
>Martin Losch // mailto:mlosch at awi-bremerhaven.de
>Alfred-Wegener-Institut für Polar- und Meeresforschung
>Postfach 120161, 27515 Bremerhaven, Germany
>Tel./Fax: ++49(471)4831-1872/1797
>http://www.awi-bremerhaven.de/People/show?mlosch
>
>  
>

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