[CF-metadata] Swath observational data

From: Thomas Lavergne <thomasl>
Date: Fri, 20 Nov 2009 14:56:08 +0000 (UTC)

Dear John,

----- "John Caron" <caron at unidata.ucar.edu> wrote:

> The geometry of each point is an interesting wrinkle, and may need
> some new conventions. would a rotated ellipse work (3 params) or do we
> need a more general polygon? Does it have to be specified per point,
> or can is be common to all points? I would imagine that quick
> visualizers might ignore the details of this (essentially assuming a
> tesselating grid), but more sophisticated and specialized tools would
> need this.

I do not thing the FOV (field of view) of single "point" should be described as projected on the Earth surface (rotated ellipse and/or polygon) if this is what you meant. It should come as a response function of angular incoming radiation. This response function might be a formula (2D Gaussian, weighted sum of 2D gaussians, etc...) or given as a Look Up Table. The Earth-projected geometry will then be a function of the view angle, Earth topography, integration (photon counting) period, etc... We should definitely be able to have response function varying within the scan array.

I think we are entering a terribly complex (and interesting) subject when defining a Feature for those space- and air-borne observational data. The question is then, where should we put the limit in complexity and what is the scope: Do we aim at encoding the "spacecraft instrument engineer" point of view or the "geophysical data user" point of view?

Cheers,
Thomas
Received on Fri Nov 20 2009 - 07:56:08 GMT