Charlie and John: Thanks for the discussion, this is really good background information for the list.
The "effective" or "radiative center" height that we retrieve can be at least 1 km below the true cloud top as measured by a lidar. We also produce a cloud top height product that matches well with lidar heights, but this parameter is a function of the "effective" height, retrieved cloud optical depth and other information. So I hesitate to use the term "cloud top" in association with the product we're discussing here because it is clear that our height is at some depth within the cloud. Kris ========================================================= Kristopher Bedka Senior Research Scientist Science Systems & Applications, Inc. @ NASA Langley Research Center Climate Science Branch 1 Enterprise Parkway, Suite 200 Hampton, VA 23666 Primary Office Phone: (757) 864-5798 Secondary Office Phone: (757) 951-1920 Fax: (757) 951-1902 kristopher.m.be...@nasa.gov ========================================================= -----Original Message----- From: Charlie Zender <zen...@uci.edu> Organization: University of California, Irvine Date: Thursday, February 13, 2014 12:31 AM To: CF Metadata Mail List <cf-metadata@cgd.ucar.edu> Cc: "Bedka, Kristopher M. (LARC-E302)[SCIENCE SYSTEMS AND APPLICATIONS, INC]" <kristopher.m.be...@nasa.gov> Subject: Re: new standard name requests Hi Kris, Try to pick a name that matches what the algorithm retrieves. What you have described seems much closer to an effective cloud top height for 11 um photons. So first I would replace the word "center" with something like "top". As you note, satellites traditionally use IR techniques to estimate cloud height. Does your product differ in practice from what some now store as height_at_cloud_top? If not, use that name. It seems like your intent is to be more precise and explicitly recognize the radiative basis of the height measurement. And I laud that because height depends on how it's measured/defined: Clouds become optically thick sooner in the IR than the visible, so visible photons might lead to a retrieval of ten to a few hundred meters (depending on condensate concentration) less in height than IR photons. Lidar is an example of a visible technique. Many models define clouds with a condensate concentration threshold. I think that the name should encode the method if the result is sensitive to the method. Possibly your retrieval algorithm already corrects for sensitivity to the method (e.g., to estimate a "wavelength-independent" height). Others will say this sensitivity to method is a given and should not be reflected in the name... If you want all that reflected in a new name, then maybe something along these lines for your quantity: height_at_radiative_cloud_top height_at_retreived_cloud_top height_at_IR_radiative_cloud_top height_at_IR_retrieved_cloud_top height_at_thermal_cloud_top height_at_11um_retrieved_cloud_top height_at_infrared_retrieved_cloud_top I prefer the last suggestion. Others with more experience at CF name construction might improve on these with this as background. Best, c -- Charlie Zender, Earth System Sci. & Computer Sci. University of California, Irvine 949-891-2429 )'( _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
