Hi All,
As a new comer to the world of metorological/oceanographic datasets, I
am currently reading up on a number of subject matters including the use
of the UDUNITS package and the use of version 1 or 2 for CF conformance.
As a result of a URL kindly provided by Mike Grant, Plymouth Marine
Laboratory I came across a posting by Andrew Clegg in March 2010:
>I'm running into some problems regarding units in CF-compliant files.
Up
>until now I've been using udunits 1 to check units, but I recently
tried
>the CF checker which uses udunits2. There are some unit strings which
>are valid in one but not the other. In particular, I am dealing with
>milligrams per cubic meter. In udunits1, I used 'ukg m^-3', which
>udunits2 rejects as invalid. udunits2 accepts 'mg m^-3' (which is much
>better!), but udunits1 interprets this as to do with gravity. Because
of
>this, I can't include a unit string which is generally compatible with
> udunits...
My query relates to the specifications quoted for dealing with
milligrams per cubic meter values, i.e. 'ukg m^-3' for version 1, and
'mg m^-3' for version 2. When I enter either value, or indeed 'mg/m3',
into my installed version 1 (v1.12.11) of 'udunits' it reports the
definition as '1e-06 kilogram metre-3' implying a unit value of
'0.000001 kg/m3' - and what I would expect, i.e. kilograms per cubic
metre.
However, when I enter the same values into my installed version 2
(v2.1.23) of 'udunits2' it reports the definition as '1e-06 m-3 kg'
implying a unit value of '0.000001 m3/kg' - and not what I would expect,
i.e. cubic metres per kilogram.
Has anyone else noted this, or can somebody correct my interpretation of
the meaning of 'm-3 kg'.
Kind regards,
Glenn Comiskey
Data System Administrator
Fugro Global Environment & Ocean Sciences
Fugro House, Hithercroft Road
Wallingford, Oxfordshire OX10 9RB, UK
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(Direct) / Fax: +44 (0) 1491 820599
E-mail: g.comiskey at geos.com <mailto:g.comiskey at g.comiskey_at_geos.com> /
Website: www.geos.com <
http://www.geos.com/>
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Received on Wed Jun 01 2011 - 10:22:25 BST
