It is important to keep in mind that the current "positive" attribute conveys only sign, not direction. The directional standard names have the direction embedded because the direction is intrinsic to the measurement. In many cases, changing the direction of these measurements changes more than just the sign!
For example, downwelling_spectral_radiance_in_air + upwelling_spectral_radiance_in_air != 0, as the quantities are fundamentally different. I believe that semantic meaning would be obfuscated if the two standard names were merged to just "spectral_radiance_in_air" with a sign-like attribute conveying direction.
Mike
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Michael A. Godin
Software Engineer
Monterey Bay Aquarium Research Institute
Phone: 831-775-2063
http://www.mbari.org
Received on Thu Jun 28 2007 - 11:10:48 BST
