Skip to content

Commit

Permalink
Merge branch 'stable' of https://github.com/OSOceanAcoustics/echopype
Browse files Browse the repository at this point in the history
…into stable
  • Loading branch information
leewujung committed Mar 7, 2024
2 parents 663f2d6 + c1f67c0 commit 94c7954
Show file tree
Hide file tree
Showing 2 changed files with 35 additions and 60 deletions.
64 changes: 4 additions & 60 deletions docs/source/processing-levels.md
Original file line number Diff line number Diff line change
@@ -1,63 +1,7 @@
# Proposed Echosounder Data Processing Levels (DRAFT)
# Echosounder data processing levels

The decades-long experience from the satellite remote sensing community has shown that a set of robust and well-articulated definitions of "data processing levels" [1][5] can lead directly to broad and highly productive use of data. Processing level designations also provide important context for data interpretation [6]. However, no such community agreement exists for active acoustic data. The ambiguity associated with the interoperability and inter-comparability of processed sonar data products has hindered efficient collaboration and integrative use of the rapidly growing data archive across research institutions and agencies.
The decades-long experience from the satellite remote sensing community has shown that a set of robust and well-articulated definitions of "data processing levels" {cite}`weaver_2014` can lead directly to broad and highly productive use of data. Processing level designations also provide important context for data interpretation {cite}`hills_2015`. However, no such community agreement exists for echosounder data. Improving the interoperability and inter-comparability of processed echosounder data products will likely facilitate efficient collaboration and integrative use of the rapidly growing data archive across research institutions and agencies.

The `echopype` team is developing a clearly defined progression of data processing levels for active ocean sonar data. The development leverages the collective experience from remote sensing and large-scale, long-term ocean and ecological observatories [7][10]. Data processing functions in `echopype` are clearly associated with specific Processing Level inputs and outputs, and when appropriate, will generate a `processing_level` dataset global attribute with entries such as "Level 1A", "Level 2B", "Level 4", etc.
To help address this gap, the echopype team is developing a clearly defined set of progression of echosounder data processing levels by leveraging the collective experience from remote sensing and large-scale, long-term ocean and ecological observatories.


## Processing Levels and Sub-levels

### Level 0 (L0)

**Description:** Raw data in vendor sensor format.

- raw binary files. Associated metadata may be found in external files.

### Level 1 (L1)

**Description:** Raw data packaged with ancillary information and converted and standardized to an open convention and standard data formats. May be distributed in the following two forms:
- as sets of individual converted files as originally segmented into arbitrary time ranges during sensor file creation, or
- compiled into larger granules corresponding to logical deployment intervals.

- **L1A**: Raw L0 data converted to a standardized, open format with geographic coordinates (latitude & longitude) included. Includes other ancillary information extracted from sensor-generated L0 data or other external sources. May include environmental information such as temperature, salinity and pressure. Use of the SONAR-netcDF4 version 1 convention is strongly recommended.
- **L1B**: L1A data with quality-control steps applied, such as time-coordinate corrections that enforce strictly increasing, non-duplicate timestamps.

### Level 2 (L2)

**Description:** Calibrated acoustic quantities at raw data resolution, with spatial coordinates included (latitude, longitude and depth)

- **L2A**: Volume backscattering strength (`Sv`) with interpolated latitude, longitude and depth coordinates. May incorporate addition information, such as split beam angle
- **L2B**: `Sv` L2A data with noise removal or other data filtering applied, including seafloor bottom removal.

### Level 3 (L3)

**Description:** Calibrated acoustic quantities regridded or aggregated to a common grid across channels. May include noise removal or other filtering.

- `Sv` resampled to a common, high-resolution grid across channels
- Mean Volume Backscattering Strength (`MVBS`)
- Masks applied to `Sv` based on different scattering source classification criteria and methods, such as frequency difference across two channels.
- **L3A**: The above variables computed on L2A data
- **L3B**: The above variables computed on L2B (filtered) data

### Level 4 (L4)

**Description:** Acoustically derived biological features, involving further processing of L3 data that may include data reduction or incorporation of external sources of data.

- Nautical Area Backscattering Coefficients (`NASC`), potentially partitioned into inferred sources of scattering
- Summary statistics of echogram features (center_of_mass, dispersion, etc)
- Taxon or species-level data labels (classification). May originate from a variety of methods, including frequency difference thresholds.
- Estimated biomass, combined or partitioned into different taxonomic sources.


## References

- [1] Parkinson, C. L., A. Ward, and M. D. King (eds.). 2006. Earth science reference handbook: A guide to NASA’s Earth Science Program and Earth Observing Satellite Missions. National Aeronautics and Space Administration. https://atrain.nasa.gov/publications/2006ReferenceHandbook.pdf
- [2] NASA. 2021. Data Processing Levels | Earthdata. Last viewed Mar. 24, 2023. https://earthdata.nasa.gov/collaborate/open-data-services-and-software/data-information-policy/data-levels/
- [3] Ramapriyan, H. K., and P. J. T. Leonard. 2021. Data Product Development Guide (DPDG) for Data Producers version1.1. NASA Earth Science Data and Information System Standards Office, 21 October 2021. https://doi.org/10.5067/DOC/ESO/RFC-041VERSION1
- [4] Robinson, I. 2006. Satellite Measurements for Operational Ocean Models, pp. 147-189. In: Chassignet, E.P. and Verron, J. (eds). Ocean Weather Forecasting: An Integrated View of Oceanography. Springer, New York, NY. https://doi.org/10.1007/1-4020-4028-8_6
- [5] Weaver, R. 2014. Processing Levels, pp. 517-520. In: Njoku, E.G. (ed). Encyclopedia of Remote Sensing. Encyclopedia of Earth Sciences Series. Springer, New York, NY. https://doi.org/10.1007/978-0-387-36699-9_36
- [6] Hills, D. J., R. R. Downs, R. Duerr, J. C. Goldstein, M. A. Parsons, and H. K. Ramapriyan. 2015. The importance of data set provenance for science. Eos, 96, Published on 4 December 2015. https://doi.org/10.1029/2015EO040557
- [7] Heaney, K., B. Martin, J. Miksis-Olds, T. Moore, J. Warren, and M. Ainslie. 2020. ADEON data processing specification. Version 1.0. Technical report by Applied Ocean Sciences for Prime Contract No. M16PC00003, Apr. 2020. https://adeon.unh.edu/sites/default/files/user-uploads/ADEON_Data%20Processing_Specification_FINAL.pdf
- [8] IFREMER. 2019. Processing Levels - Oceanographic Data. Last viewed Mar. 24, 2023. http://en.data.ifremer.fr/All-about-data/Data-management/Processing-levels
- [9] NEON. 2023 Data Processing | NSF NEON | Open Data to Understand our Ecosystems. Last viewed Mar. 24, 2023. https://www.neonscience.org/data-samples/data-management/data-processing
- [10] OOI. 2023. Ocean Observatories Initiative: Glossary - Data Terminology. Ocean Observatories Initiative. Last viewed Mar. 24, 2023. https://oceanobservatories.org/glossary/#DATATERMS
Check out the [echolevels](http://echolevels.readthedocs.io/) document for the current status, and please chime in with any [input or questions via GitHub issues](https://github.com/uw-echospace/data-processing-levels/issues/new)!
31 changes: 31 additions & 0 deletions docs/source/references.bib
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ @article{DeRobertis2007_noise
year = {2007},
pages = {1282--1291},
}

@techreport{Demer2015,
title = {Calibration of acoustic instruments},
institution = {ICES Cooperative Research Report, No. 326},
Expand All @@ -16,6 +17,7 @@ @techreport{Demer2015
doi = {10.17895/ices.pub.5494},
pages = {133 pp},
}

@article{MacKenzie1981,
title = {Nine-term equation for sound speed in the oceans},
volume = {70},
Expand All @@ -26,6 +28,7 @@ @article{MacKenzie1981
pages = {807--812},
doi = {10.1121/1.386920},
}

@article{Ainslie1998,
title = {A simplified formula for viscous and chemical absorption in sea water},
volume = {103},
Expand All @@ -39,3 +42,31 @@ @article{Ainslie1998
note = {Publisher: Acoustical Society of America},
pages = {1671--1672},
}

@incollection{weaver_2014,
address = {New York, NY},
series = {Encyclopedia of {Earth} {Sciences} {Series}},
title = {Processing {Levels}},
isbn = {978-0-387-36699-9},
language = {en},
booktitle = {Encyclopedia of {Remote} {Sensing}},
publisher = {Springer},
author = {Weaver, Ron},
editor = {Njoku, Eni G.},
year = {2014},
doi = {10.1007/978-0-387-36699-9_36},
pages = {517--520},
file = {Full Text PDF:/Users/wujung/Zotero/storage/K8CUALCF/Weaver - 2014 - Processing Levels.pdf:application/pdf},
}

@misc{hills_2015,
title = {The {Importance} of {Data} {Set} {Provenance} for {Science}},
url = {http://eos.org/opinions/the-importance-of-data-set-provenance-for-science},
abstract = {Data do not exist in a vacuum. To be useful, data must be accompanied by context on how they are captured, processed, analyzed, and validated and other information that enables interpretation and use.},
language = {en-US},
urldate = {2023-10-23},
journal = {Eos},
author = {Hills, D. J. and Downs, R. R. and Duerr, R. and Goldstein, J. C. and Parsons, M. A. and Ramapriyan, H. K.},
month = dec,
year = {2015},
}

0 comments on commit 94c7954

Please sign in to comment.