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[CF-metadata] Decibel units in CF standard names

From: Moroni, David F <David.F.Moroni>
Date: Mon, 12 Nov 2018 06:24:26 +0000

John and others interested,

I was part of the initial request that dated back to 2014. Here?s the original GitHub ticket (still open) capturing the correspondence with the UDUNITS team: https://github.com/Unidata/UDUNITS-2/issues/33

I was corresponding with ?mhidas? and ?semmerson?, so I don?t know if these people are still on this project, as no further correspondence has taken place since July 2015. I made another attempt last year to bring some life to this request, but to no avail.

There was another user inquiring about representing dB as a unit, but that ticket has since closed and it?s not clear to me from the thread whether there was a positive resolution. Here?s that link: https://github.com/r-quantities/units/issues/176

Others on here are more than welcome to pursue this further.

Cheers,
David

From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of John Graybeal <jbgraybeal at mindspring.com>
Date: Sunday, November 11, 2018 at 9:33 PM
To: Jonathan Gregory <j.m.gregory at reading.ac.uk>
Cc: CF Metadata List <cf-metadata at cgd.ucar.edu>
Subject: Re: [CF-metadata] Decibel units in CF standard names

Just as an aside (or maybe not), the udunits support list has been asked before to include dB, and I understood that they had (I think I actually saw it, but can?t find written confirmation). So it wouldn?t surprise me if the library included dB.

In case it?s useful I pasted in a bit of the old thread below.

john
---------------------------------------
John Graybeal
jbgraybeal at mindspring.com<mailto:jbgraybeal at mindspring.com>



On Nov 4, 2018, at 09:03, Jonathan Gregory <j.m.gregory at reading.ac.uk<mailto:j.m.gregory at reading.ac.uk>> wrote:

Dear Martin

Your points are good ones and have been raised before. More than once we have
talked about maintaining a CF version of the udunits definition to include dB
and sverdrup, or ask udunits to add them (if they're not there). dB is a dimen-
sionless unit, equivalent to 1. I suggest that dBZ should be changed to dB,
as I don't think we ought to have several of them. I believe that the default
reference levels are mostly conventional and stated in the definitions of the
standard name, as you say. They can be overridden by supplying a size-one or
scalar coordinate variable. You have previously suggested an xml table to
contain more information about the definition of standard names, haven't you?
It seems to me that an arrangement like that would be the right place to store
the default reference levels and scale factor in a machine-readable way.

Best wishes

Jonathan

----- Forwarded message from Martin Juckes - UKRI STFC <martin.juckes at stfc.ac.uk<mailto:martin.juckes at stfc.ac.uk>> ??






Begin forwarded message:

From: "Moroni, David F (398M)" <David.F.Moroni at jpl.nasa.gov<mailto:David.F.Moroni at jpl.nasa.gov>>
Subject: Re: [CF-metadata] [cf-satellite] normalized_radar_backscatter_coefficient
Date: August 8, 2014 at 3:10:50 PM PDT
To: John Graybeal <john.graybeal at marinexplore.com<mailto:john.graybeal at marinexplore.com>>, "rhorne at excaliburlabs.com<mailto:rhorne at excaliburlabs.com>" <rhorne at excaliburlabs.com<mailto:rhorne at excaliburlabs.com>>
Cc: "Weiss, Barry H (398B)" <barry.h.weiss at jpl.nasa.gov<mailto:barry.h.weiss at jpl.nasa.gov>>, Jonathan Gregory <j.m.gregory at reading.ac.uk<mailto:j.m.gregory at reading.ac.uk>>, "cf-satellite at unidata.ucar.edu<mailto:cf-satellite at unidata.ucar.edu>" <cf-satellite at unidata.ucar.edu<mailto:cf-satellite at unidata.ucar.edu>>, CF Metadata List <cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>>

Hi John,

Thanks for providing the email link. I've already emailed Unidata and they are processing my request to include dB within UDUNITS.

Cheers,
David

From: John Graybeal <john.graybeal at marinexplore.com<mailto:john.graybeal at marinexplore.com>>
Date: Friday, August 8, 2014 10:57 AM
To: "rhorne at excaliburlabs.com<mailto:rhorne at excaliburlabs.com>" <rhorne at excaliburlabs.com<mailto:rhorne at excaliburlabs.com>>
Cc: "Weiss, Barry H (398B)" <barry.h.weiss at jpl.nasa.gov<mailto:barry.h.weiss at jpl.nasa.gov>>, David F Moroni <David.F.Moroni at jpl.nasa.gov<mailto:David.F.Moroni at jpl.nasa.gov>>, Jonathan Gregory <j.m.gregory at reading.ac.uk<mailto:j.m.gregory at reading.ac.uk>>, "cf-satellite at unidata.ucar.edu<mailto:cf-satellite at unidata.ucar.edu>" <cf-satellite at unidata.ucar.edu<mailto:cf-satellite at unidata.ucar.edu>>, CF Metadata List <cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>>
Subject: Re: [CF-metadata] [cf-satellite] normalized_radar_backscatter_coefficient

This request has now been made by me of UDUNITS on general principle, but I think individuals could also express their desire as a way to move the ball forward.

John

On Aug 7, 2014, at 07:57, rhorne at excaliburlabs.com<mailto:rhorne at excaliburlabs.com> wrote:


Dear Barry and David:

For udunits support, send an email to support-udunits at unidata.ucar.edu<mailto:support-udunits at unidata.ucar.edu>.



very respectfully,

randy



________________________________
From: "Weiss, Barry H (398B)" <barry.h.weiss at jpl.nasa.gov<mailto:barry.h.weiss at jpl.nasa.gov>>
Sent: Thursday, August 07, 2014 10:06 AM
To: "Moroni, David F (398M)" <David.F.Moroni at jpl.nasa.gov<mailto:David.F.Moroni at jpl.nasa.gov>>, "Jonathan Gregory" <j.m.gregory at reading.ac.uk<mailto:j.m.gregory at reading.ac.uk>>
Cc: "Niedfeldt, John C (398M-Affiliate)" <John.C.Niedfeldt at jpl.nasa.gov<mailto:John.C.Niedfeldt at jpl.nasa.gov>>, "CF Metadata List" <cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>>, "John Graybeal" <john.graybeal at marinexplore.com<mailto:john.graybeal at marinexplore.com>>, "cf-satellite at unidata.ucar.edu<mailto:cf-satellite at unidata.ucar.edu>" <cf-satellite at unidata.ucar.edu<mailto:cf-satellite at unidata.ucar.edu>>
Subject: Re: [cf-satellite] [CF-metadata] normalized_radar_backscatter_coefficient

Jonathan,

As the data product engineer for the SMAP project, I second David's
request.

We are attempting to employ CF metadata in our products. This is not a
challenge at level 2 and above where our products provide geophysical
measure, but is a challenge at level 1, where our products provide
instrument measurements.

Please consider inclusion of dB units. That should include dB based on
unit less measure, as well as dB relative to watts and volts.

Thanks and Regards,

Barry


On 8/6/14 7:49 PM, "Moroni, David F (398M)" <David.F.Moroni at jpl.nasa.gov<mailto:David.F.Moroni at jpl.nasa.gov>>
wrote:

>Hi Jonathan,
>
>Just as follow up from my last email, I noticed an online email exchange
>where you had responded to a request to use units of dB (decibels) even
>though it is not currently in the udunits database:
>http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/056572.html
>
>We also agree it would be wise to include dB in the udunits database, and
>we will be applying these units for our scatterometer datasets.
>
>We hope to see this incorporated in the near future.
>
>Thanks again for your considerations.
>
>Cheers,
>David
>


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