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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@xxxxxxxxxxxxxxxxx wrote: > Dear Barry and David: > > For udunits support, send an email to support-udunits@xxxxxxxxxxxxxxxx. > > > > very respectfully, > > randy > > > > From: "Weiss, Barry H (398B)" <barry.h.weiss@xxxxxxxxxxxx> > Sent: Thursday, August 07, 2014 10:06 AM > To: "Moroni, David F (398M)" <David.F.Moroni@xxxxxxxxxxxx>, "Jonathan > Gregory" <j.m.gregory@xxxxxxxxxxxxx> > Cc: "Niedfeldt, John C (398M-Affiliate)" <John.C.Niedfeldt@xxxxxxxxxxxx>, "CF > Metadata List" <cf-metadata@xxxxxxxxxxxx>, "John Graybeal" > <john.graybeal@xxxxxxxxxxxxxxxx>, "cf-satellite@xxxxxxxxxxxxxxxx" > <cf-satellite@xxxxxxxxxxxxxxxx> > 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@xxxxxxxxxxxx> > 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 > > > >On 8/5/14 7:24 PM, "Moroni, David F (398M)" <David.F.Moroni@xxxxxxxxxxxx> > >wrote: > > > >>Hi John, > >> > >>We will incorporate these constant coordinate variables as you've > >>recommended. > >> > >>Since during this 2+ month comment period we have not received any > >>objections on our proposed inclusion of > >>normalized_radar_backscatter_coefficient as a CF standard_name, we will > >>now proceed with applying this as a standard_name for our relevant > >>scatterometer datasets. > >> > >>On to our next concern: when will our proposed standard name become > >>officially adopted into the CF standard name listing? > >> > >>Timing is not super critical, but considering what I perceive to be a > >>consensus during this exchange of emails, we would at least like to > >>obtain > >>a statement of confirmation from the CF folks that this standard name > >>will > >>be adopted. > >> > >>A simple, brief email response from the chair or co-chair of this > >>committee would suffice. > >> > >>Thank you again for your consideration and generous feedback. > >> > >>Cheers, > >>David > >> > >> > >>On 7/23/14 9:32 PM, "John Graybeal" <john.graybeal@xxxxxxxxxxxxxxxx> > >>wrote: > >> > >>>Hi David, > >>> > >>>Thanks for the question. Constant coordinate variables are hopefully not > >>>a big deal -- they can be easily specified as scalar coordinate > >>>variables, as noted in the example here: > >>>http://cfconventions.org/Data/cf-convetions/cf-conventions-1.7/build/cf- > >>>c > >>>o > >>>nventions.html#scalar-coordinate-variables. > >>> > >>>That's an example for analysis time and pressure level, but it's OK to > >>>use coordinate variables for any critical reference variable. (Chapter > >>>4: > >>>"Coordinate types other than latitude, longitude, vertical, and time are > >>>allowed." Incidentally, the text in reference [1] was proposed as a > >>>replacement for that sentence in http://kitt.llnl.gov/trac/ticket/100, > >>>which has been accepted but not implemented.) > >>> > >>>I had to search the archives to fully understand the motivation, here's > >>>what I found (ooh, FAQ question!): > >>> (1) To locate the data in an axis other than space or time. [1] > >>> (2) To provide a consistent way to specify the value of a certain > >>>other > >>>parameter, or even multiple parameters; if the parameter is unvarying, > >>>it > >>>can be specified as a scalar. [2] > >>> > >>>So your declaration that both the radiation wavelength and scatter angle > >>>were essential led to my suggestion. Adopting it standardizes the method > >>>for citing the needed information (consistent with other standard names, > >>>and across users of this standard name), thereby maximizing > >>>interoperability. > >>> > >>>By all means reply further if this seems problematic, I'm at the edge of > >>>my experience but others can jump in. > >>> > >>>John > >>> > >>>[1] On Apr 11, 2013, at 12:45, Jonathan Gregory > >>><j.m.gregory@xxxxxxxxxxxxx> wrote: > >>> > >>>> The commonest use of coordinate variables is to locate the data in > >>>>space and > >>>> time, but coordinates may be provided for any other continuous > >>>>geophysical > >>>> quantity (e.g. density, temperature, radiation wavelength, zenith > >>>>angle of > >>>> radiance, sea surface wave frequency) or discrete category (see > >>>>Section 4.5, > >>>> "Discrete axis", e.g. area type, model level number, ensemble member > >>>>number) > >>>> on which the data variable depends. > >>> > >>> > >>>[2] On Dec 24, 2010, at 13:26, Jonathan Gregory > >>><j.m.gregory@xxxxxxxxxxxxx> wrote: > >>> > >>>> We quite often recommend, for instance in connection with particular > >>>>standard names, > >>>> that the value of a certain other parameter could be specified, e.g. a > >>>> radiation_wavelength for radiative quantities. Scalar coord vars are a > >>>>neat > >>>> way to do this. They are something between multivalued coord vars and > >>>> attributes in terms of function: easier than coord vars, and more > >>>>powerful > >>>> than attributes because they can themselves have attributes. > >>> > >>>[3] > >>> > >>> > >>>On Jul 23, 2014, at 17:39, Moroni, David F (398M) > >>><David.F.Moroni@xxxxxxxxxxxx> wrote: > >>> > >>>> Hi John (G), > >>>> > >>>> John (N) and myself are working together on this effort. > >>>> > >>>> Thanks for your inputs here. > >>>> > >>>> In general, I agree with the first part of your revision of the > >>>>description, but I don't suggest including a reference to the > >>>>coordinate > >>>>values for the other standard names as you've suggested, namely > >>>>"radiation_wavelength" and "scattering_angle", simply because this type > >>>>of measurement assumes: 1) constant wavelength and 2) constant > >>>>scattering angle. I simply don't follow your reasoning for why such > >>>>coordinate values would be needed given the nature of these values > >>>>being > >>>>constant. Can you provide some rationale as to why we would want to > >>>>list > >>>>these as coordinate values? > >>>> > >>>> Cheers, > >>>> David > >>>> > >>>> ================================================== > >>>> David Moroni > >>>> Ocean Wind and Scatterometry Data Engineer > >>>> Physical Oceanography Distributed Active Archive Center > >>>> Jet Propulsion Laboratory > >>>> 4800 Oak Grove Dr > >>>> M/S 158-242 > >>>> Pasadena, CA 91109 > >>>> Phone: 818.354.2038 > >>>> Fax: 818.353.2718 > >>>> ================================================== > >>>> > >>>> From: John Graybeal <john.graybeal@xxxxxxxxxxxxxxxx> > >>>> Date: Wednesday, July 23, 2014 3:52 PM > >>>> To: "Niedfeldt, John C (398M-Affiliate)" > >>>><John.C.Niedfeldt@xxxxxxxxxxxx> > >>>> Cc: CF Metadata List <cf-metadata@xxxxxxxxxxxx>, David F Moroni > >>>><David.F.Moroni@xxxxxxxxxxxx> > >>>> Subject: Re: [CF-metadata] normalized_radar_backscatter_coefficient > >>>> > >>>>> Hi John (N), > >>>>> > >>>>> Thanks for the detailed explanation. I am convinced the new term is > >>>>>distinct. I did not expect to redefine the old term unless one was > >>>>>clearly a refinement of the other, which is not the case. > >>>>> > >>>>> I still am concerned about the description I think you are proposing > >>>>>for this term ("normalized_radar_backscatter_coefficient is also > >>>>>called > >>>>>the normalized radar cross section, which are commonly used in the > >>>>>microwave remote sensing community.") Based on your inputs, here is a > >>>>>second attempt: > >>>>> > >>>>>> The fraction of incident power at a given wavelength that reaches a > >>>>>>receiver, after reflection by a surface at a given reflection angle. > >>>>>>(In microwave remote sensing this is also known as the 'normalized > >>>>>>radar cross section' or 'sigma naught'.) Coordinate values for > >>>>>>radiation wavelength and reflection angle should be given the > >>>>>>standard > >>>>>>names radiation_wavelength and scattering_angle. > >>>>> > >>>>> This description reflects: always 1 wavelength; always 1 backward > >>>>>scattering angle; and that all lost power is included in the > >>>>>coefficient, not simply the surface reflectance/absorption. > >>>>> > >>>>> If I correctly got your 3 points, the term "attenuated" applies, as > >>>>>it > >>>>>is used elsewhere in CF: "'The attenuated backwards scattering > >>>>>function > >>>>>includes the effects of two-way attenuation by the medium between a > >>>>>radar source and receiver." Since I can't imagine needing an > >>>>>unattenuated backscatter coefficient, the extra word seems unneeded > >>>>>for > >>>>>this name. > >>>>> > >>>>> John (G) > >>>>> > >>>>> On Jul 23, 2014, at 10:37, Niedfeldt, John C (398M-Affiliate) > >>>>><John.C.Niedfeldt@xxxxxxxxxxxx> wrote: > >>>>> > >>>>>> Dear John et al, > >>>>>> Here are three major distinctions between the > >>>>>>surface_backwards_scattering_coefficient_of_radar_wave (old) and > >>>>>>normalized_radar_backscatter_coefficient (new): > >>>>>> € The (old) definition has the default definition as being an > >>>>>>integral over all wavelengths, but the radar backscatter coefficient > >>>>>>is always measured using one wavelength (new) and must always be > >>>>>>specified. > >>>>>> € The part about scattering radiation having no loss in energy in > >>>>>>the (old) definition is not clear, but in practice and theory energy > >>>>>>is always lost once the initial wave is transmitted (indeed, it is in > >>>>>>part the loss due to the ground that we are measuring)(new). > >>>>>> € The backscatter in the (old) definition refers to summing all > >>>>>>backwards scattering angles, where in remote sensing we look at just > >>>>>>one backscatter angle (new). > >>>>>> And yes, if the old variable pertains to the normalized radar cross > >>>>>>section--which I believe it does not--then the transmitted wavelength > >>>>>>and backscatter angle (elevation angle) should be required as they > >>>>>>are > >>>>>>essential to understanding the product and being able to correlate > >>>>>>and > >>>>>>verify data. > >>>>>> > >>>>>> So yes, we could change the old definition to meet the new needs, > >>>>>>but > >>>>>>it would require a change in base assumptions that would render any > >>>>>>current data using that standard name as invalid. For these reasons > >>>>>>and more, I believe we should make a new standard name. The > >>>>>>definition > >>>>>>I have provided is accurate and once approved additional attributes > >>>>>>and values can be made required to suit all needs for those dealing > >>>>>>with the normalized radar backscatter coefficient. > >>>>>> > >>>>>> Sincerely, > >>>>>> John > >>>>>> > >>>>>> -- > >>>>>> John Niedfeldt > >>>>>> Data Engineering > >>>>>> PO.DAAC, JPL > >>>>>> > >>>>>> From: John Graybeal <john.graybeal@xxxxxxxxxxxxxxxx> > >>>>>> Date: Tuesday, July 22, 2014 at 3:53 PM > >>>>>> To: JPL <John.C.Niedfeldt@xxxxxxxxxxxx> > >>>>>> Cc: CF Metadata List <cf-metadata@xxxxxxxxxxxx>, "Moroni, David F > >>>>>>(398M)" <David.F.Moroni@xxxxxxxxxxxx> > >>>>>> Subject: Re: [CF-metadata] normalized_radar_backscatter_coefficient > >>>>>> > >>>>>> John, I think we (I, anyway) were waiting for a little more > >>>>>>clarification as to what was needed. Sorry for that delay. I like > >>>>>>the > >>>>>>name itself, makes sense to me. > >>>>>> > >>>>>> Unless I am mistaken, from your email I infer that the meaning of > >>>>>>this is a narrow case of > >>>>>>surface_backwards_scattering_coefficient_of_radar_wave. That > >>>>>>description is: > >>>>>>> The scattering/absorption/attenuation coefficient is assumed to be > >>>>>>>an integral over all wavelengths, unless a coordinate of > >>>>>>>radiation_wavelength is included to specify the wavelength. > >>>>>>>Scattering of radiation is its deflection from its incident path > >>>>>>>without loss of energy. Backwards scattering refers to the sum of > >>>>>>>scattering into all backward angles i.e. scattering_angle exceeding > >>>>>>>pi/2 radians. Ascattering_angle should not be specified with this > >>>>>>>quantity. > >>>>>> > >>>>>> I can't tell from the description if this item is different, so the > >>>>>>description could use a little bit more meat to tease that out. > >>>>>>Looking at your thread, I see this: > >>>>>> > >>>>>>> we are calculating sigma_naught which is the fraction of incident > >>>>>>>power that is reflected by the surface. It is also very important in > >>>>>>>scatterometry to record the angle of incidence as the sigma_naught > >>>>>>>changes based on the incidence angle in addition to various other > >>>>>>>parameters which are essential to being able to correlate data from > >>>>>>>various scatterometers. > >>>>>> > >>>>>> So does it work for the description could say something like the > >>>>>>following? This is still similar to the other standard name, so if > >>>>>>there are specific things that make the distinction clear that would > >>>>>>be important to add. ("This differs from surface_backwards_...") > >>>>>> > >>>>>>> The fraction of incident power that is reflected by the surface. > >>>>>>>(In > >>>>>>>microwave remote sensing this is also known as the 'normalized > >>>>>>>radar > >>>>>>>cross section' or 'sigma naught', when produced from one angle of > >>>>>>>incidence and from one wavelength.) Scattering of radiation is its > >>>>>>>deflection from its incident path without loss of energy. Backwards > >>>>>>>scattering refers to the sum of scattering into all backward angles > >>>>>>>i.e. scattering_angle exceeding pi/2 radians. A scattering_angle > >>>>>>>should not be specified with this quantity. Coordinates of > >>>>>>>radiation_wavelength and angle_of_incidence are used to specify > >>>>>>>those > >>>>>>>baseline parameters. > >>>>>> > >>>>>> I'm not sure about the last part -- if they are always needed these > >>>>>>variables should be required. > >>>>>> > >>>>>> John > >>>>>> > >>>>>> > >>>>>> > >>>>>> On Jul 22, 2014, at 14:49, Niedfeldt, John C (398M-Affiliate) > >>>>>><John.C.Niedfeldt@xxxxxxxxxxxx> wrote: > >>>>>> > >>>>>>> Dear all, > >>>>>>> Hello again! About two months back I sent in a request, which is > >>>>>>>referenced below, in which I requested that we add the > >>>>>>>Œnormalized_radar_backscatter_coefficient¹ in CF. Having heard > >>>>>>>nothing to the contrary, and seeing as no other standards name match > >>>>>>>our needs, we at PO.DAAC will be moving forward in implementing this > >>>>>>>new standard name. > >>>>>>> > >>>>>>> As our newly reprocessed netCDF datasets shall soon serve as an > >>>>>>>online replacement for existing datasets already in use by hundreds > >>>>>>>of interdisciplinary scatterometry data users, we hope to likewise > >>>>>>>hear back from you soon as to whether there is consensus on our > >>>>>>>proposed standard name. If there is anything further we can do to > >>>>>>>build community consensus on our proposed standard name, please let > >>>>>>>me know. > >>>>>>> > >>>>>>> Sincerely, > >>>>>>> John > >>>>>>> > >>>>>>> -- > >>>>>>> John Niedfeldt > >>>>>>> Data Engineering > >>>>>>> PO.DAAC, JPL > >>>>>>> > >>>>>>> From: Lauret Olivier <olauret@xxxxxx> > >>>>>>> Date: Friday, May 30, 2014 at 8:11 AM > >>>>>>> To: "cf-metadata@xxxxxxxxxxxx" <cf-metadata@xxxxxxxxxxxx> > >>>>>>> Cc: JPL <John.C.Niedfeldt@xxxxxxxxxxxx> > >>>>>>> Subject: TR: normalized_radar_backscatter_coefficient > >>>>>>> > >>>>>>> Hi all, > >>>>>>> > >>>>>>> Just forwarding you some discussion we have with J. Niedfeldt about > >>>>>>>some standard name for sigma naught variable. I thought the > >>>>>>>available > >>>>>>>³surface_backwards_scattering_coefficient_of_radar_wave² could be > >>>>>>>used considering some changes in the definition [in short I wish we > >>>>>>>could mix the description of sigma naught from radar altimetry with > >>>>>>>the one from scatterometers]. But it seems that the quantities are > >>>>>>>different enough to introduce a new standard name (see the message > >>>>>>>below). > >>>>>>> > >>>>>>> Can we introduce Œnormalized_radar_backscatter_coefficient¹ in CF? > >>>>>>> > >>>>>>> Thanks, > >>>>>>> > >>>>>>> Olivier > >>>>>>> > >>>>>>> De : Niedfeldt, John C (398M-Affiliate) > >>>>>>>[mailto:John.C.Niedfeldt@xxxxxxxxxxxx] > >>>>>>> Envoyé : jeudi 29 mai 2014 21:26 > >>>>>>> À : Lauret Olivier > >>>>>>> Objet : normalized_radar_backscatter_coefficient > >>>>>>> > >>>>>>> Dear Mr. Olivier, > >>>>>>> After discussion with Dr. David Long of BYU and reviewing the > >>>>>>>current definition with him it was determined that we do in fact > >>>>>>>need > >>>>>>>a new variable. In microwave remote sensing the normalized radar > >>>>>>>cross section, sigma naught, is always produced from one angle of > >>>>>>>incidence and from one wavelength. I understand the desire to > >>>>>>>consolidate the number of standard names and to not have > >>>>>>>duplication, > >>>>>>>but adding this standard name would reduce confusion and error for > >>>>>>>many I believe. It is also general enough that we can add attributes > >>>>>>>to it in the future to allow further specification for various > >>>>>>>endeavors. If you have any more questions feel free to contact me > >>>>>>>and > >>>>>>>thank you again for your assistance. We changed the standard_name to > >>>>>>>be more descriptive. > >>>>>>> > >>>>>>> standard_name: > >>>>>>> normalized_radar_backscatter_coefficient > >>>>>>> > >>>>>>> Definition: > >>>>>>> normalized_radar_backscatter_coefficient is also called the > >>>>>>>normalized radar cross section, which are commonly used in the > >>>>>>>microwave remote sensing community. > >>>>>>> > >>>>>>> Canonical Units: > >>>>>>> 1 > >>>>>>> > >>>>>>> > >>>>>>> Sincerely, > >>>>>>> John Niedfeldt > >>>>>>> > >>>>>>> > >>>>>>> Cliquez ici si ce message est indésirable (pourriel). > >>>>>>> > >>>>>>> _______________________________________________ > >>>>>>> CF-metadata mailing list > >>>>>>> CF-metadata@xxxxxxxxxxxx > >>>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > >>>>>> > >>>>>> _______________________________________________ > >>>>>> CF-metadata mailing list > >>>>>> CF-metadata@xxxxxxxxxxxx > >>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > >>>>> > >>> > >> > > > >_______________________________________________ > >cf-satellite mailing list > >cf-satellite@xxxxxxxxxxxxxxxx > >For list information or to unsubscribe, visit: > >http://www.unidata.ucar.edu/mailing_lists/ > > _______________________________________________ cf-satellite mailing list > cf-satellite@xxxxxxxxxxxxxxxx For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ > <Attachment 1>_______________________________________________ > CF-metadata mailing list > CF-metadata@xxxxxxxxxxxx > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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