[MITgcm-devel] seaice_budget_ice

[Martin Losch]

Thanks Jinlun,
but then, what is the meaning of the of the term
surface_emissivity*lwdown?
(surface is both ice and ocean for the respective cases in budget) I  
would have thought that the radiation that is emitted by the surface  
is upward radiation, not downward. Or does one parameterize the  
emitted radiation as .97*lwdown?

Martin

On 27 Dec 2006, at 17:51, Jinlun Zhang wrote:

> Hi Martin,
> 0.97 is surface emissivity.
> Jinlun
>
> Martin Losch wrote:
>
>> Hi Jinlun, Dimitris,
>>
>> Please forgive me, if I am confused about all these constants:
>> I am currently trying to implement some radiation-bulk formulae  
>> that  estimate lwdown from air and ocean temperature, humidity,  
>> because  apparently for the Arctic the reanalysis fields for  
>> lwdown (and  swdown) are not very good (this is what my Arctic  
>> specialists Gerdes,  Karcher, Kauker, Koeberle tell me). The  
>> seaice-pkg has some remains  of the original Parkinson&Washington  
>> bulk formulae in it, which is  close to what we want to have for  
>> the Arctic (for comparison  reasons), so I want to understand what  
>> the individual contributions are.
>> So: What is the 0.97? ice emissivity? why then have .97*lwdown,  
>> if  lwdown is not affected by the surface? Or is it some sort of  
>> albedo  for long wave radiation? What variable name should I give  
>> to this  number?
>>
>> Martin
>>
>> On 27 Dec 2006, at 07:23, Dimitris Menemenlis wrote:
>>
>>> Martin, why do you think that emissivity is already part of   
>>> lwdown?  My understanding of the NCEP and ERA fields is that  
>>> lwdown  and swdown are radiation fields prior to any interaction  
>>> with sea  surface, as opposed to lwnet and swnet, which include  
>>> interaction  with sea surface.  A more serious issue is  
>>> potentially the lack of  realism of the representation of  
>>> atmospheric boundary layer  processes, especially in NCEP  
>>> reanalysis, which is the older of the  two.
>>>
>>> A second comment is that by default we bypass the   
>>> seaice_budget_ocean bulk formulae and instead use that of pkg/exf.
>>>
>>> Dimitris
>>>
>>>> Whatever forcing one uses, make sure 0.97 is not used twice. Jinlun
>>>> Martin Losch wrote:
>>>>
>>>>> Hi there,
>>>>> why is lwdown (now lwdownLoc) mulitplied by 0.97 in   
>>>>> seaice_budget_ice
>>>>> (formerly budget)? This looks awfully like some ocean surface    
>>>>> emissivity,
>>>>> which is already part of lwdown if I am not mistaken.  (the  
>>>>> same  is true
>>>>> for seaice_budget_ocean, also formerly budget.)
>>>>> I think that this is wrong.
>>>>> Martin
>>>>
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>>
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>
> -- 
>
> Jinlun Zhang
> Polar Science Center, Applied Physics Laboratory
> University of Washington, 1013 NE 40th St, Seattle, WA 98105-6698
>
> Phone: (206)-543-5569;  Fax: (206)-616-3142
> zhang at apl.washington.edu
> http://psc.apl.washington.edu/pscweb2002/Staff/zhang/zhang.html
>
>
>
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