[MITgcm-devel] bloc and bloc in shelfice_thermodynamics

[Menemenlis, Dimitris (329D)]

done

> On Oct 1, 2015, at 12:15 AM, Martin Losch <Martin.Losch at awi.de> wrote:
> 
> Hi Dimitris,
> 
> the only reason for this is to save one floating point operation. I agree that is this can be confusing and I myself stumble last week over something like this in the seaice_evp code that I wrote myself.
> 
> I guess performance isn’t an issue here, so go ahead and change it for clarity
> 
> M.
> 
>> On 01 Oct 2015, at 01:08, Menemenlis, Dimitris (329D) <Dimitris.Menemenlis at jpl.nasa.gov> wrote:
>> 
>> Hi Martin, Yoshi and I wonder why you don’t multiply uLoc and vLoc by 0.5 in lines below:
>> 
>>         uLoc(I,J) = recip_hFacC(I,J,K,bi,bj) *
>>    &         ( uVel(I,  J,K,bi,bj) * _hFacW(I,  J,K,bi,bj)
>>    &         + uVel(I+1,J,K,bi,bj) * _hFacW(I+1,J,K,bi,bj) )
>>         vLoc(I,J) = recip_hFacC(I,J,K,bi,bj) *
>>    &         ( vVel(I,J,  K,bi,bj) * _hFacS(I,J,  K,bi,bj)
>>    &         + vVel(I,J+1,K,bi,bj) * _hFacS(I,J+1,K,bi,bj) )
>> 
>>           uLoc(I,J) = ( uLoc(I,J) * drF(K)*_hFacC(I,J,K,bi,bj)
>>    &           + drKp1 * recip_hFacC(I,J,Kp1,bi,bj) *
>>    &           ( uVel(I,  J,Kp1,bi,bj) * _hFacW(I,  J,Kp1,bi,bj)
>>    &           + uVel(I+1,J,Kp1,bi,bj) * _hFacW(I+1,J,Kp1,bi,bj) )
>>    &           ) * recip_drLoc
>>           vLoc(I,J) = ( vLoc(I,J) * drF(K)*_hFacC(I,J,K,bi,bj)
>>    &           + drKp1 * recip_hFacC(I,J,Kp1,bi,bj) *
>>    &           ( vVel(I,J,  Kp1,bi,bj) * _hFacS(I,J,  Kp1,bi,bj)
>>    &           + vVel(I,J+1,Kp1,bi,bj) * _hFacS(I,J+1,Kp1,bi,bj) )
>>    &           ) * recip_drLoc
>> 
>> You do it later on in line:
>> 
>>           ustarSq = shiCdrag * MAX( 1.D-6,
>>    &           0.25 _d 0 *(uLoc(I,J)*uLoc(I,J)+vLoc(I,J)*vLoc(I,J)) )
>> 
>> The problem with this formulation is that if one is trying to modify
>> drag formulation, it’s very easy to forget that uLoc = 2 * u
>> (Yoshi spent days tracking this missing factor :-(
>> 
>> Shall we change for clarity?
>> 
>> Cheers, Dimitris