[Esip-documentation] ACDD-1.3 documentation change request: Descriptions of "resolution" attributes

[Aaron Sweeney]

Hi, folks,

       I want to bring to your attention a problem with the ACDD-1.3 
documentation that is leading to the creation of invalid ISO 19115-2 
metadata records.

       Specifically, I am referring to the Descriptions of the following 
Suggested global attributes: geospatial_lat_resolution, 
geospatial_lon_resolution, and geospatial_vertical_resolution.  For 
reference and clarity, I've included these attributes (as well as their 
related units attributes) and their descriptions from the ACDD-1.3 
documentation 
<http://wiki.esipfed.org/index.php/Attribute_Convention_for_Data_Discovery_1-3> 
below this message.

       There are two problems with the Description of these 
"resolutions."  The first is the recommendation to include both a 
numerical value and unit.  The ncISO tool expects these resolutions to 
be numeric only.  This leads to the creation of invalid ISO 19115-2 
records.  The second problem is that the Description does not require 
the unit of resolution to be the same as the corresponding 
"geospatial_[lat|lon|vertical]_unit."

       I would advocate that the Description of resolution explicitly 
state that a numeric value is expected and that the value be expressed 
in the same unit as specified in the corresponding 
"geospatial_[lat|lon|vertical]_unit" attribute.

Cordially,
Aaron

----relevant ACDD-1.3 documentation follows----

 1. geospatial_lat_units: Units for the latitude axis described in
    "geospatial_lat_min" and "geospatial_lat_max" attributes. These are
    presumed to be "degree_north"; other options from udunits may be
    specified instead.
 2. geospatial_lat_resolution: Information about the targeted spacing of
    points in latitude. Recommend describing resolution as a number
    value followed by the units. Examples: '100 meters', '0.1 degree'
 3. geospatial_lon_units: Units for the longitude axis described in
    "geospatial_lon_min" and "geospatial_lon_max" attributes. These are
    presumed to be "degree_east"; other options from udunits may be
    specified instead.
 4. geospatial_lon_resolution: Information about the targeted spacing of
    points in longitude. Recommend describing resolution as a number
    value followed by units. Examples: '100 meters', '0.1 degree'
 5. geospatial_vertical_units: Units for the vertical axis described in
    "geospatial_vertical_min" and "geospatial_vertical_max" attributes.
    The default is EPSG:4979 (height above the ellipsoid, in meters);
    other vertical coordinate reference systems may be specified. Note
    that the common oceanographic practice of using pressure for a
    vertical coordinate, while not strictly a depth, can be specified
    using the unit bar. Examples: 'EPSG:5829' (instantaneous height
    above sea level), 'EPSG:5831' (instantaneous depth below sea level).
 6. geospatial_vertical_resolution: Information about the targeted
    vertical spacing of points. Example: '25 meters'



-- 
Aaron D. Sweeney
Water Level Data Manager

Cooperative Institute for Research in Environmental Sciences (CIRES)
University of Colorado at Boulder
and
NOAA National Geophysical Data Center
Marine Geology and Geophysics Division
325 Broadway, E/GC3
Boulder, CO 80305-3328

Phone: 303-497-4797, Fax: 303-497-6513

DISCLAIMER: The contents of this message are mine personally and do not necessarily reflect any position of NOAA.

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