Proposed Echosounder Data Processing Levels (DRAFT)

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 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.

Processing Levels and Sub-levels

Level 0 (L0)

Description: Raw data in vendor sensor format.

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:

Level 2 (L2)

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

Level 3 (L3)

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

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.

References