Hello Karl,
in udunits "sr", "steradian" and "radian^2", "radian2" are all equivalent. I think we could use "sr". This unit is already used in the term "volume_scattering_function_of_radiative_flux_in_air_due_to_ambient_aerosol_particles", which has units "m-1 sr-1" and is defined as a "flux per unit solid angle".
I believe the term "solid angle" is general enough to be used for an arbitrary shape: it is the area of a the shape projected onto a unit sphere.
It is clear from the context of your proposal that the quantity you are interested in is a solid angle relative to the Earth's centroid, whereas the solid angle in the definition of the term above is relative to the scattering particle. It may be worth considering making explicit reference to the fact that this term is a geocentric solid angle in the standard name, e.g. "solid_angle_from_geocenter" (analogous to the existing term "distance_from_geocenter").
regards,
Martin
________________________________
From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of Taylor, Karl E. <taylor13 at llnl.gov>
Sent: 02 March 2019 17:36
To: cf-metadata at cgd.ucar.edu
Subject: [CF-metadata] angular areas
Hi all,
Certain conservative regridding applications use "angular area" in
mapping from a source to destination grid. Some of these applications
record the areas in units of radians squared (i.e., they compute the
fraction of spherical area occupied by the grid cell and then multiply
it by 4*pi.
I would like to define a new standard name to use with these "angular
areas". Would the following be appropriate?
standard_name = "solid_angle"
units = "steradian" (abbrev. "sr")
Is "solid_angle" general enough to represent any shaped region on the
spherical surface?
Does udunits allow "sr", or should it be "radian**2"
best wishes,
Karl
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Received on Mon Mar 04 2019 - 04:46:34 GMT
