Metadata Report for BODC Series Reference Number 2219372

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Access Policy

Open Data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

Narrative Documents

Kongsberg EM122 12kHz Multibeam Echosounder

The EM122 is designed to perform seabed mapping to full ocean depth with a high resolution, coverage and accuracy. Beam focusing is applied both during reception and transmission. The system has up to 288 beams/432 soundings per swath with pointing angles, which are automatically adjusted according to achievable coverage or operator defined limits.

This model uses both Continuous Wave and Frequency Modulated sweep pulses with pulse compression on reception, in order to increase the maximum useful swath width. The transmit fan is split in several individual sectors, with independent active steering, in order to compensate for the vessel movements.

In multiplying mode, two swaths per ping cycle are generated, with up to 864 soundings. The beam spacing is equidistant or equiangular and the transmit fan is duplicated and transmitted with a small difference in along track tilt, which takes into account depth coverage and vessel speed, to give a constant sounding separation along track. In high density mode, more than one sounding per beam can be produced, such that horizontal resolution is increased and is almost constant over the whole swath.

The EM122 transducers are modular linear arrays in a Mills cross configuration with separate units for transmit and receive. If used to deliver sub-bottom profiling capabilities with a very narrow beamwidth, this system is known as SBP120 Sub-Bottom Profiler.

The specification sheet can be accessed here Kongsberg EM122.

Specifications

EM122 versions

JC257 SMARTEX Bathymetry: Originator's Data Processing

Sampling Strategy

Kongsberg EM122 multibeam bathymetry data were collected on board RRS James Cook JC257 from 8th February to 19th March 2024. This was the second SMARTEX cruise to the Clarion Clipperton Zone (CCZ) in the northern equatorial Pacific, an area likely to be targeted for deep-sea mining for polymetallic nodules. JC257 aimed to collect additional multibeam data during transits to further map the seafloor in regions not yet surveyed. The data were collected to obtain a better insight in the biodiversity patterns and benthic habitat distributions within the CCZ, by scientists from the National Oceanography Centre, Southampton, UK.

The data collection was funded under the SMARTEX project: Seabed Mining And Resilience To EXperimental impact, under NERC grant reference NE/T003537/1. Further information is available in the cruise report.

Data Processing

Shipboard multibeam data were collected using a 512 beam Kongsberg EM122 system that was solely used for the survey. It was a 12kHz system with a 150° swath width and equidistant beam sampling. Datafiles were divided into 2 hour passes.

Multibeam data acquisition began once the ship left the Costa Rican EEZ. Routes to and from Costa Rica were designed to run parallel to the tracks from previous cruise JC241. A marine mammal (MMO) watch was done before soft starting the multibeam system over 20 minutes. The system remained on throughout the cruise, excluding mooring recovery, where the system was switched off to prevent interference with the beacon communication. Data was only logged when the vessel was at speeds of more than 2 knots. Transits were done at 10-11 knots and whenever timing allowed, additional multibeam lines were planned to compliment existing bathymetry data. Routes to and from Costa Rica were designed to run parallel to JC241 tracks, except where Glider/ CTD deployment or ship time limitations did not allow.

The multibeam and backscatter data was recorded in the Kongsberg .all format. Caris Hips and Sips v10.4 was used for processing the data, with a zero tide file. CTD and model derived sound velocity profiles were applied during data acquisition. Backscatter was collected and viewed in Caris Hips and Sips v11.4. Data quality was dependent on weather and heading.

JC257 SMARTEX Bathymetry: Processing by BODC

The multibeam bathymetry grid from JC257 at the Clarion Clipperton Zone (CCZ) were supplied to BODC as a .txt ASCII file at 100m resolution. Data were transferred into a common format, a netCDF subset. The following table shows how the variables within the files were mapped to the appropriate BODC parameter codes:

Following transfer, the data are screened visually, using BODC's in-house visualisation software, and any spikes or instrument malfunctions are clearly labelled with quality control flags.

Project Information

SMARTEX - Seabed Mining And Resilience To EXperimental impact

SMARTEX is a four year (2021-2025) Strategic Research programme funded by the Natural Environment Research Council (NERC) under lead grant reference NE/T003537/1. The deep sea environment is about to be subjected to unprecedented levels of direct anthropogenic disturbance from deep-sea mining, with unknown consequences for its ecosystems. SMARTEX will tackle the fundamental question of how deep-sea ecosystems respond to and recover from broad-scale disturbance.

Background

Over a 6 million square km region of the central Pacific ocean, at abyssal depths of almost five thousand metres, lies a vast mineral resource in the form of small potato-sized deposits called polymetallic nodules. They are highly-enriched in metals of importance for industry, including the development of new sustainable technologies. Although the region lies in international waters, countries have now signed 16 exploration contracts with a UN-organised international regulator and the United Kingdom is sponsor to two of these, covering an area more than the size of England. It is a requirement of both the regulator and the sponsoring state to ensure that serious harm is avoided to the marine ecosystem in this region - a hitherto untouched deep-sea wilderness.

Developing a sustainable approach to polymetallic nodule mining is a challenge as the nature and importance of the Pacific abyssal ecosystem is largely unknown, as are the capacity of the ecosystem to cope with and recover from mining impacts. The project aims to provide the critical scientific understanding and evidence-base to reduce the risks of this industrial development, taking advantage of new and unique opportunities to solve these problems in a single programme.

Participants

A number of organisations are involved in the programme, listed below:

• National Oceanography Centre (NOC) - Lead Research Organisation
• British Geological Survey (BGS)
• Scottish Association of Marine Science (SAMS)
• University of Liverpool
• University of Southampton
• Heriot-Watt University
• Plymouth Marine Laboratory
• Natural History Museum
• Joint Nature Conservation Committe (JNCC)

Research details

The priorities and aims of this project are:

• To understand background variability in key ecosystem parameters across the CCZ with a focus on the UK contracted regions
• To assess the immediate physio-chemical impacts of polymetallic nodule mining disturbance and the resulting effects on the ecosystem (ecological resistance)
• To quantify the long-term resilience of the ecosystem to deep-sea mining (assess the return to baseline conditions on at least decadal scales)

Fieldwork and data collection

Field data and samples will be collected on two cruises (JC241 and JC257) to the Clarion-Clipperton Zone in the central Pacific Ocean. Researchers will begin by assessing the water and its dynamic flows over time and space. The complex physical environment will be monitored for a year to capture its variabilities, particularly "storm events" near the seabed. Researchers will use this to make predictions about where the sediment plume generated by mining will be transported and settle back to the seafloor.

Researchers will then assess the linkages between the water, sediment surface and sub sediments, evaluating the natural cycling of nutrients and metals that is important to maintain ecosystem health. The impacts of mining and recovery of these processes will be assessed. Mining will lead to changes in the structure of the seabed, its shape and the physical nature of the sediments, which will be mapped and linked to biological patterns. The biological processes that lead to these patterns will be assessed by detailing the life histories and reproduction of the organisms present and their connectivity between areas near and far, and then determining their role in maintaining structured communities of life, a high biodiversity and a functioning food web.

The functions in the ecosystem that these organisms provide will be evaluated, which help maintain a healthy ecosystem. The impact of mining and recovery of all these patterns and processes will be determined using the experimental areas to assess the biological and functional consequences of disturbance in the deep sea. These changes are likely complex, so a range of mathematical models will be used to better understand and predict the consequences of mining activities at larger time and space scales. Such predictive power, along with the evidence from the scientific assessment, will provide information that is critical for understanding and reducing the environmental risk of future mining activities.

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

No Fixed Station Information held for the Series

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: