Hello Andrew and Jonathan,
First, I think this discussion is heading towards reasonable compromise avoiding my concerns of a massive proliferation in cell methods and the pitfall of concepts that are explainable in the context of their parameter, but meaningless in isolation (e.g. explaining moments without the concept of frequency).
Now for my views on 'common concepts'. This was a very good idea that so far has drowned in a quagmire of over-commitment. Bad news is that it's nearly a year since I left Hamburg allaying Michael and Frank's frustrations with an enthusiasm to make progress that was instantly swamped by day job issues when I returned to the office.
Good news is that I am now involved (with co-workers and support) in an EU FP7 project and discovered at the project meeting last week that is going to need precise semantic interoperability between CF and SeaDataNet. In other words an exact mapping between the BODC Parameter Usage Vocabulary (P011) and data channels in CF. A mapping between P011 and CF Standard Names isn't going to cut the mustard for all the reasons that 'common concepts' were mooted to address. So, if this project is to progress operational common concepts will have to be implemented by next summer at the latest.
So, my view on common concepts has recently become much more positive and I am therefore comfortable with the latest proposal.
Cheers, Roy.
-----Original Message-----
From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of andrew walsh
Sent: 13 October 2010 01:00
To: Jonathan Gregory
Cc: cf-metadata at cgd.ucar.edu; Mark Kulmar
Subject: Re: [CF-metadata] Seeking new CF standard names (9) for sea surface wave parameters
Hi Jonathon and CF metadata list,
My responses are in-line below.
Andrew Walsh
----- Original Message -----
From: "Jonathan Gregory" <j.m.gregory at reading.ac.uk>
To: "andrew walsh" <awalsh at metoc.gov.au>
Cc: "Patrick Gorringe" <Patrick.Gorringe at utas.edu.au>; <greg at metoc.gov.au>;
"Mark Kulmar" <Mark.Kulmar at mhl.nsw.gov.au>; <cf-metadata at cgd.ucar.edu>; "Roger
Proctor" <Roger.Proctor at utas.edu.au>
Sent: Wednesday, October 13, 2010 03:09
Subject: [CF-metadata] Seeking new CF standard names (9) for sea surface wave
parameters
> Dear Andrew
>
> Thanks - this is a fruitful discussion. I think we agree on proposing these
> new names
>
> sea_surface_wave_height
Yes, but depends on the community (list) accepting the idea of having a common
concept
of 'sea_surface_wave_height' modified by the cell methods to get particular
meanings
for 4 of the 9 proposed wave parameters as follows:
CF std. name; "cell_method"; constructed meaning (name)
First 2 parameters would use new cell methods:
1) sea_surface_wave_height; "time: root_mean_square";
sea_surface_wave_height_root_mean_square
2) sea_surface_wave_height; "time:
mean_of_upper_decile";sea_surface_wave_height_mean_of_upper_decile
These 2 parameters would use existing cell methods:
3) sea_surface_wave_height; "time: mean"; sea_surface_wave_height_mean
4) sea_surface_wave_height; "time: maximum"; sea_surface_wave_height_maximum
List readers, I would appreciate any feedback on the idea of using
common concept + cell_method?
> sea_surface_wave_mean_crest_period
> sea_surface_wave_significant_wave_period
Yes, these 2 OK.
>
> You have proposed a new name
> sea_surface_wave_period_at_second_largest_peak_of_the_energy_spectrum
> (to replace an earlier proposal). Is this the "second" corresponding to this
> existing name being the "first":
> sea_surface_wave_period_at_variance_spectral_density_maximum
> and if so, could your new quantity be
> sea_surface_wave_period_at_second_largest_peak_of_variance_spectral_density
> for consistency?
Yes, I this would be more consistent.
>
> Thanks for your explanation of sea_surface_wave_zeroth_spectral_moment. That
> leads me to ask whether it could be called
> sea_surface_wave_variance_spectral_density_zeroth_frequency_moment
> to correspond to the terminology used in the existing names
>
> sea_surface_wave_mean_period_from_variance_spectral_density_first|second_frequency_moment
Yes it could be called that, again fits in with existing terminology.
>
> Finally, you have explained that
> sea_surface_wave_root_mean_square_amplitude
> is the square root of the zeroth moment. It is liable to be confused with the
> root_mean_square sea_surface_wave_height. Would it be acceptable to call it,
> rather clumsily,
>
> sea_surface_wave_amplitude_from_variance_spectral_density_zeroth_frequency_moment
> which follows the pattern of the names of wave periods calculated from
> moments?
> If it is always called sea_surface_wave_root_mean_square_amplitude and that
> doesn't cause any confusion in practice, we don't need to worry about it. But
> you did point out "not be confused with", so I suppose it might be a problem!
I think
'sea_surface_wave_amplitude_from_variance_spectral_density_zeroth_frequency_moment'
is longer/more clumsy than it needs to be. How about just
'sea_surface_wave_root_mean_square_amplitude_from_variance_spectral_density'
with a the 'description' in the CF XML stating that:
"The sea surface wave root mean square amplitude (Yrms) is derived from the wave
energy spectrum
zeroth spectral moment (M0) which is the area under the wave energy spectrum
(variance spectral density) curve. Yrms is the square root of the zeroth
spectral moment (M0) i.e Yrms=sqrt(M0)
This wave parameter is not to be confused with the root mean square wave height
which is
calculated from a zero crossing analysis of the wave height time series data
recording."
With this name and description it is not likely to be confused with
'sea_surface_wave_height' + cell method (root_mean_square).
>
> We are also going to propose two new cell_methods
>
> root_mean_square
> mean_of_upper_decile.
>
> We have to do that in the trac system but it's not a large change to the
> convention.
>
> Best wishes
>
> Jonathan
>
>
_______________________________________________
CF-metadata mailing list
CF-metadata at cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
--
This message (and any attachments) is for the recipient only. NERC
is subject to the Freedom of Information Act 2000 and the contents
of this email and any reply you make may be disclosed by NERC unless
it is exempt from release under the Act. Any material supplied to
NERC may be stored in an electronic records management system.
Received on Wed Oct 13 2010 - 01:57:15 BST
