[MITgcm-devel] seaice_budget_ice

[Martin Losch]

OK, got the message (o:
I'll get a copy tomorrow.

Martin
On 27 Dec 2006, at 19:01, Jinlun Zhang wrote:

> Hi Martin,
>
> Parkinson&Washington gives a very nice description about  
> surface_emissivity. It lists all the components of surface heat  
> flux, really an excellent paper about ice thermodynamics.
>
> Jinlun
>
> Martin Losch wrote:
>
>> 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
>>>>>>
>>>>>>
>>>>> _______________________________________________
>>>>> MITgcm-devel mailing list
>>>>> MITgcm-devel at mitgcm.org
>>>>> http://mitgcm.org/mailman/listinfo/mitgcm-devel
>>>>
>>>>
>>>>
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