Standard names: additional active acoustic standard names

[jcermauwedu]

Proposer's name: John Horne (jhorne@uw.edu), Mark Yamane (mtyamane@uw.edu) and Rob Cermak (jcerma@uw.edu)

Date: 18 March 2024

Notes: We would like to propose additional standard names so that proposed active acoustic information may be added to the IOOS Glider DAC and meets compliance requirements through use of the IOOS Compliance Checker. The related publication for this proposal may be found here, https://academic.oup.com/icesjms/article/69/2/184/701699, with the primary reference Urmy et. al (2012) doi:10.1093/icesjms/fsr205. Some of these have already been defined in a prior accepted proposal (#153). Community software impacts include the IOOS Compliance Checker (https://github.com/ioos/compliance-checker), echopype (https://github.com/OSOceanAcoustics/echopype), pyglider (https://github.com/c-proof/pyglider) and GUTILS (https://github.com/SECOORA/GUTILS). Issues will be raised and linked to this issue so they will have an opportunity to make comments and suggestions. Notice will also be placed in appropriate Slack channels on UG2 and IOOS to raise additional awareness.

Proposed Names

acoustic_proportion_occupied_in_sea_water Description: Acoustic proportion occupied is occupied volume divided by the volume sampled. Occupied volume is the integral of the ratio of acoustic_volume_backscattering_strength_in_sea_water above -90 dB to the reference value, 1 m2 m-2. For further details see Urmy et. al (2012) doi:10.1093/icesjms/fsr205. Units: 1

acoustic_index_of_aggregation_in_sea_water Description: Acoustic index of aggregation is the depth integral of squared volume backscattering coefficient divided by the squared area backscattering coefficient. Volume backscattering coefficient is the linear form of acoustic_volume_backscattering_strength_in_sea_water. Area backscattering coefficient is the integral of the volume backscattering coefficient over a defined distance. The parameter is computed to provide a value that represents the patchiness of biomass in the water column in the field of fisheries acoustics - the value is high when small areas are much denser than the rest of the distribution. The parameter is also the reciprocal of acoustic_equivalent_area_in_sea_water. For further details see Urmy et. al (2012) doi:10.1093/icesjms/fsr205 and Woillez et. al (2007) doi.org/10.1093/icesjms/fsm025. Units: m-1

acoustic_centre_of_mass_in_sea_water Description: Acoustic centre of mass is the average of all sampled depths weighted by their volume backscattering coefficient. Volume backscattering coefficient is the linear form of acoustic_volume_backscattering_strength_in_sea_water. For further details see Urmy et. al (2012) doi:10.1093/icesjms/fsr205. Units: m

acoustic_inertia_in_sea_water Description: Acoustic inertia is the sum of squared distances from the acoustic_centre_of_mass weighted by the volume backscattering coefficient at each distance and normalized by the total area backscattering coefficient. Volume backscattering coefficient is the linear form of acoustic_volume_backscattering_strength_in_sea_water. Area backscattering coefficient is the integral of the volume backscattering coefficient over a defined distance. For further details see Urmy et. al (2012) doi:10.1093/icesjms/fsr205 and Bez and Rivoirard (2001) doi:10.1016/S0165-7836(00)00241-1. Units: m-2

acoustic_equivalent_area_in_sea_water Description: Acoustic equivalent area is the squared area backscattering coefficient divided by the depth integral of squared volume backscattering coefficient. Area backscattering coefficient is the integral of the volume backscattering coefficient over a defined distance. Volume backscattering coefficient is the linear form of acoustic_volume_backscattering_strength_in_sea_water. The parameter is computed to provide a value that represents the area that would be occupied if all data cells contained the mean density and is the reciprocal of acoustic_index_of_aggregation_in_sea_water. For further details see Urmy et. al (2012) doi:10.1093/icesjms/fsr205 and Woillez et. al (2007) doi.org/10.1093/icesjms/fsm025. Units: m

[github-actions[bot]]

Thank you for your proposal. These terms will be added to the cfeditor (http://cfeditor.ceda.ac.uk/proposals/1) shortly. Your proposal will then be reviewed and commented on by the community and Standard Names moderator.

[efisher008]

Dear Rob @jcermauwedu,

Thank you for your proposal. I have added the names to the CF editor as "under discussion". Am I correct in thinking that the quantities acoustic_index_of_aggregation_in_sea_water (with units m-1) and acoustic_inertia_in_sea_water (with units m-2) are calculated per metre and per square metre, respectively?

Best regards (and happy Easter/Ramadan), Ellie

[mtyamane]

Hi Ellie @efisher008,

Yes, those units are correct. The units are calculated in Urmy et al. 2012. Let us know if there are any other questions!

Thanks,

Mark

[efisher008]

Dear Mark @mtyamane ,

Thank you for your reply and for linking the paper (the same goes for the proposal notes). Having read the paper and reviewed the names, I agree that they look suitable for inclusion in the standard names table. One thing I noticed is that the metric "centre of mass" has notation M for units in Table 1 of the paper, but the proposed standard name acoustic_centre_of_mass_in_sea_water has units of m. Is there a significance to the capitalised M in the table?

Is there a reason for not including the acoustic metric "number of layers" from Table 1 in this proposal? Would this be useful to have a standard name for, from your perspective? If this is not generalisable as a quantity in active acoustics beyond the analysis in the paper, perhaps not. I can see that "Mean volume-backscattering strength" and "Area-backscattering strength" already have standard names conforming to the same format as the new proposed names.

Best regards, Ellie

[efisher008]

Hi Mark @mtyamane,

Did you have anything to add regarding my question about acoustic_centre_of_mass_in_sea_water here?

Best wishes, Ellie

[mtyamane]

Hi Ellie @efisher008 ,

After speaking with one of the co-authors of the Urmy et al. 2012 paper, the M is supposed to be lower-case and signify meters. "Number of layers" currently does not have a standard way to be calculated in active acoustics, so we are not proposing that metric just yet.

Mark

[efisher008]

Hi Mark @mtyamane,

Thank you for checking - the units are correct in the CF editor given this explanation. We can move ahead with the proposed standard names without adding "number of layers" to the proposal.

Best wishes, Ellie

[jcermauwedu]

@efisher008 Thank you for your valuable input and insight to this proposal. What is our next step? Are there any remaining issues?