Dear All,
My view on this is that I would include sea ice as 'honorary land' when it comes to skin temperatures on the basis that both are solid rather than liquid, which fits in with Nathan's suggestion of having the new term cover any skin temperatures that aren't measured on liquid water.
Cheers, Roy.
________________________________
From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Evan Manning [Evan.M.Manning at jpl.nasa.gov]
Sent: 30 June 2013 16:10
To: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] new standard name: land_surface_skin_temperature
Now we'll have sea_surface_skin_temperature and land_surface_skin_temperature.
Will we also add an ice_surface_skin_temperature?
This raises issues of what the land & sea surface skin temperatures are when
there is ice or snow over the dirt or ocean. Is it the temperature where land meets
ice or where ice meets air?
>From my perspective with AIRS, looking down through the atmosphere at the
Earth, the answer is clearly that we sense the surface at the bottom of the
atmosphere, whether it is land, ice/snow, water, or some combination of those.
I'd like us to have a "surface_skin_temperature" and use "area_fraction"-family
fields to tell users what portion of the observed area is frozen or
what portion is liquid. This mirrors what we currently do in non-CF HDF
products.
I don't object to also having "sea_surface_skin_temperature" etc. Presumably
with an observation of an extended area where part is land and part is sea,
the sea_surface_skin_temperature would be the temperature of the part
that is sea. If part of the sea portion is covered in ice, would that part be
included in the sea_surface_skin_temperature?
Ditto land?
-- Evan
On Fri, Jun 14, 2013 at 11:45 AM, <cf-metadata-request at cgd.ucar.edu<mailto:cf-metadata-request at cgd.ucar.edu>> wrote:
Thanks for your comments. They all make sense to me and I'm on board with your suggested definition. I'll just wait for others to comment, if needed, then we can converge on a final definition. Sincerely,
Jonathan
On 6/14/2013 2:11 PM, Jim Biard wrote:
Jonathan,
I still don't believe that the surface temperature concept that Jonathan Gregory has ever been what people were intending when they make the surface_temperature standard name, but I'll abide by whatever folks decide.
On a different front, I don't think the definition of the standard name should include statements about technology used (measured by an infrared radiometer?). The definition should speak only to the measured quantity, without reference to the way in which you happen to be measuring it. Likewise, there is no need for the statement regarding variability of the quantity. Also, the surface in this name is not the lower boundary of the atmosphere. It is the upper boundary of the land. An non-volatile object in a hard vacuum has a surface skin temperature.
Given all that, I'd suggest this for your definition:
Standard Name: land_surface_skin_temperature
Definition: The land surface skin temperature is the aggregate temperature of the "skin" of the land surface, which extends vertically approximately 12 micrometers below the land surface.
If people really think it needs to be spelled out even further, add the sentence "The land surface is the upper boundary of the land."
Grace and peace,
Jim
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