[CF-metadata] Clarifications on latitude_longitude

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 25 Jun 2014 17:28:39 +0100

Dear Eizi

> Yes the default is the spherical latitude and longitude. But practically
> we often compare locations in such datasets with locations in common
> ellipsoidal CRS such as WGS84. If a default CRS is to be defined that
> should be WGS84. I don't think anybody want automatic conversion of
> latitudes from spherical to ellipsoidal - that means 20 km of shift in
> midlatitudes.

Not all data is real-world data. In fact possibly the majority of CF data in
archives (the CMIP data) is model data, for which a spherical model Earth is
often correct, and that's why it's the default. If this is not appropriate, a
grid_mapping should be included to specify the ellipsoid.

Best wishes

Jonathan
Received on Wed Jun 25 2014 - 10:28:39 BST