Hello Jonathan,
The term 'statistics' has a slightly different meaning for wave data. Essentially, what wave instrumentation does is record vertical displacement of the sea surface at very high frequency for a period of say ten minutes. Spectral analysis techniques are then used to derive 'statistics', such as the period and direction of the most energetic waves, the average height of the highest 1/3 of the displacements (one definition of significant wave height), from the raw spectra. This process is repeated every hour or so.
Consequently, the usable data comprise an hourly set of 'statistics' at a given location. Describing the derived values as 'parameterisations' might give a clearer picture of what they represent. I therefore think that these belong in standard names rather than cell methods.
Cheers, Roy.
-----Original Message-----
From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
Sent: 17 September 2010 16:22
To: andrew walsh
Cc: Patrick Gorringe; cf-metadata at cgd.ucar.edu; Katherine Tattersall; Mark Kulmar; greg at metoc.gov.au; Moninya Roughan; Roger Proctor; Paul Tildesley; Pauline Mak
Subject: [CF-metadata] Seeking new CF standard names (9) for sea surface wave parameters
Dear Andrew
Thanks for your list of wave height names. Although the standard name table
already contains some wave quantities which are defined statistically (as
you know, such as significant wave height) this larger list makes me wonder
if describing the statistics in the standard name remains the right approach.
This is not generally what we do in CF. For example, time-mean, maximum and
minimum are not indicated in standard names, but by the cell_methods attribute.
Is the idea of these quantities that they describe the statistics of wave
height observed over a long period at a given location? If so, perhaps we
could distinguish them by cell_methods rather than standard_name.
Best wishes
Jonathan
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Received on Fri Sep 17 2010 - 09:33:50 BST
