[MITgcm-support] Atmospheric emissivity in Cheapaml

[Bruno Deremble]

Hello Sanjiv,

I think you are right, this is a typo. there is a typo in the paper
too...

I think the boundary layer temperature budget is ok because we do 
xalwu - xalwd

however, for the ocean, the downward longwave is wrong. I usually use a
prescribed downward longwave option so I didn't notice this issue; I'll
fix it asap

cheers,
bruno



On Tuesday, Feb 05 2019, 18:38:50, quentin <quentinjamett at gmail.com> wrote:
> Hello Sanjiv,
>
> To my understanding, the 0.5 at the end of those two equations refers to 
> the up/down repartition of the atmospheric longwave radiations, i.e. 
> half goes upward and half goes downward, while the atmospheric 
> emissivity is set to 1 here.
>
> Hope that helps.
>
> Best,
>
> Quentin
>
>
>
> Le 2/5/19 à 11:38 AM, Sanjiv Ramachandran a écrit:
>>
>> Hi all,
>>
>>  I have a question regarding the value of the atmospheric 
>> emissivity used by cheapaml. Here is a snippet of code from the file 
>> cheapaml.F computing the upward longwave radiation (xalwu) emitted 
>> through the top of the ABL and the downward radiation (xalwd) through 
>> the "bottom" (= reference height of atmospheric variables in cheapaml).
>>
>>
>>  xalwu = stefan*(0.5*Tair(i,j,bi,bj)+0.5*ttt+celsius2K)**4
>>  & *0.5 _d 0
>>
>>  xalwd = stefan*(Tair(i,j,bi,bj)+celsius2K)**4*0.5 _d 0
>>
>>
>> In each of these expressions, there is a 0.5 at the end of the 
>> expression. Is that supposed to be the atmospheric emissivity?
>>
>>
>> Thanks,
>>
>>
>> Sanjiv Ramachandran
>>
>> UMass Dartmouth
>>
>>
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