nautical area scattering coefficient

[rmendels]

I am working with someone on restructuring some of their data into netcdf files. The main variable is "nautical area scattering coefficient". I do not see that in the standard names list, but it is something I know little about and don't know if there is another name that is equivalent. Any help appreciated.

Thanks,

-Roy

[roy-lowry]

This is a biomass proxy related to acoustic scattering in the water column and is part of the standard terminology described in the paper by McClennan et al (https://academic.oup.com/icesjms/article/59/2/365/619652).

There are three existing Standard Names for terms from this paper:

acoustic_area_backscattering_strength_in_sea_water acoustic_volume_backscattering_strength_in_sea_water acoustic_target_strength_in_sea_water

Drafting an additional Standard Name proposal from the paper should be straightforward.

[rmendels]

Hi Roy:

Thanks for the info. Let me talk to the subject matter people I am working with - as I said I know very little about this.

If anyone has a sample netcdf file with acoustic backscatter data in it, if they could send me the header that would be great. Right now we are leaning to "trajectories", as the data were collected by an underway ship.

[rmendels]

Hi Roy:

We will indeed draft a proposed standard name. Can I run it by you before we formally submit? I have pointed the people I am working with to the description of the other 3 variables so that they have an idea of what to write.

[roy-lowry]

Happy to do that for you. Note that I only look at my work e-mail about once a week these days.

[gavinmacaulay]

If doing a standard name for nautical area scattering coefficient (NASC), I suggest also doing one for the related quantity - area backscattering coefficient. They differ by a factor of $4 \pi (1852)^2$ and both are in use for estimating biomass from backscatter.

I am also happy to help you with the text for proposed standard names for these backscatter terms, but if you are at the SWFSC, you probably have access to experienced acoustic people anyway :)

@rmendels - regarding netCDF for these sort of data, have a look at https://github.com/ices-publications/SONAR-netCDF4 and https://github.com/ices-publications/AcMeta. The former is for storing the raw backscatter data (i.e., what comes out of the instrument) and gridded versions of that. The latter contains naming conventions and metadata for NASC-type data, so might be directly relevant to your work. You'll find NASC data in netCDF format (using the AcMeta convention) at AODEN: https://portal.aodn.org.au/search (in the 'IMOS Bio-Acoustic Ships of Opportunity (BA SOOP)' data collection).

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