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Metadata is data that provides information about other data, not the content of the data, but often links to the data itself. For the purposes of the AusSeabed Data Hub the metadata collected includes the following types:

• Descriptive metadata— the descriptive information about a resource. It is used for discovery and identification. It includes elements such as title, abstract, author, and keywords

• Structural metadata— metadata about containers of data and indicates how compound/complex objects are put together, for example, what formats data exists in and how the data is structured into containers or folders. It describes the types, versions, conventions, relationships and other characteristics of digital materials

• Administrative metadata— the information to help manage a resource, like resource type, permissions, and when and how it was created, when it was last updated.

• Reference metadata— the information about the contents such as references, citations and quality of data

• Statistical/Process metadata, also called process data, may describe processes that collect, process, or produce data

• Legal/Ownership metadata— provides information about the creator, copyright holder, and public licensing, if provided.

This specification is focussed on defining the requirements for a Survey. For the purposes of this specification the term ‘Survey’ is synonymous with Mission or Voyage and represents the highest level metadata from which specific data collections are captured. The Survey may utilise a platform other than a Ship (ie Satellite, Plane, Drove, or AUV) and so the term Voyage was discounted. Mission was deemed to be a broader concept and therefore Survey became the preferred termBathymetry is the measure of sea floor depth. Bathymetric mapping of the oceans is equivalent to mapping topography on land, which has vast utility and applications for science, the public, governments and industry.  Very little is known about large areas of the sea floor. For these areas, existing maps of the sea floor are low resolution, having been derived from satellites or inversion of potential field geophysical data, and only provide a general indication of water depth. Bathymetric data is collected in multiple ways e.g., satellite, single beam echo sounder (SBES) and multibeam echo sounder (MBES); and MBES data is considered as the most accurate acquisition method, after decades of global use and collection. Despite efforts to unify MBES acquisition, processing and delivery, there are no globally recognised standards to adhere to. Currently, there are many organisations using various acquisition systems and parameters, processing strategies and data formats that limit the usability and interoperability of MBES data, particularly when attempting to combine datasets to map large regions of the seabed. Therefore, defining MBES specifications for L2 products (Table 1) is an important step towards standardisation and data optimisation.  

Table 1. AusSeabed data level L2 definition.