Publicly available bathymetry and geophysical data has been used to map geomorphic features of the Antarctic continental margin and adjoining ocean basins at scales of 1:1-2 million. The key bathymetry datasets used were GEBCO08 and ETOPO2 satellite bathymetry (Smith & Sandwell 1997), in addition to seismic lines in key areas. Twenty-seven geomorphic units were identified based on interpretation of the seafloor bathymetry with polygons digitised by hand in ArcGIS. Seafloor features were classified largely based on the International Hydrographic Organisation (2001) classification of undersea features, and expanded to include additional features, including those likely to have specific substrate types and influence on oceanography. This approach improves the technique as a predictor of physical conditions that may influence seafloor communities. The geomorphic map has been used for developing a benthic bioregionalisation and for developing a representative system of Marine Protected Areas for East Antarctica. Slight modifications have been made since original publication in O'Brien et al. 2009 and Post et al. 2014. These include: - updating of some feature names; - combining "wave affected banks" with "shelf banks" - Combining "coastal terrance" with "island coastal terrane" as "Coastal/Shelf Terrane" - replacing canyon vectors with polygons by using a buffer around the vectors Further details of the original mapping can be found in: O'Brien, P.E., Post, A.L., Romeyn, R., 2009. Antarctic-wide geomorphology as an aid to habitat mapping and locating Vulnerable Marine Ecosystems, Commission for the Conservation of Antarctic Marine Living Resources Vulnerable Marine Ecosystems Workshop, Paper WS-VME-09/10. CCAMLR, La Jolla, California, USA. Post, A.L., Meijers, A.J.S., Fraser, A.D., Meiners, K.M., Ayers, J., Bindoff, N.L., Griffiths, H.J., Van de Putte, A.P., O'Brien, P.E., Swadling, K.M., Raymond, B., 2014. Chapter 14. Environmental Setting, In: De Broyer, C., Koubbi, P., Griffiths, H.J., Raymond, B., d'Udekem d'Acoz, C., et al. (Eds.), Biogeographic Atlas of the Southern Ocean. Scientific Committee on Antarctic Research, Cambridge, pp. 46-64.

<p>Six camera tow transects were completed during survey IN2017-V01 on the RV Investigator in January to March 2017. This survey focussed on the upper slope and outer continental shelf on the Sabrina Coast seafloor in East Antarctica. Camera tows targeted seafloor depths between 480 and 1680 m. Imagery was collected using the Marine National Facilities Deep Tow Camera. This system collects oblique downward facing still images with a Canon 1DX and high definition video with a Canon C300. Four DSP&L 3150 High Output SeaLite Sphere lights were used, with MicroSeaLasers providing a 10cm scale guide on the images. Several sensors are also attached to the towed body, including a SBE 37 for CTD measurements, a Kongsberg Mesotech – 1007D altimeter, a Druck PMP 5074 pressure sensor and two Sonardyne USBLs for locational accuracy of the towed body. The USBL failed for tow A008CAM02, with locations recorded as ship’s position instead and camera position based on layback calculations. Images failed to record on A004CAM01, with only 2 images saved. Due to a timing error between the images and the other sensors, there is an offset between the CTD, altimeter and pressure data and the images. This is currently being resolved by the MNF. Tows were designed to run down slope to reduce potential for colliding with the bottom. All tows were run with a ship speed over the ground of approximately 2 kt. All still images were saved in jpeg format with video footage recorded to HD1080i50 format. The video data is unclipped and includes descent and ascent in the water column. Following collection still images were colour corrected in Adobe Photoshop to remove the blue bias. <p>Images are available on the NCI with the following file structure: <p>MARINE IMAGERY COLLECTION <p>└─ PLATFORM_NAME <p> └─ CAMPAIGN_NAME <p> └─ DEPLOYMENT_NAME <p> ├─ images/ <p> └─ metadata.csv <p>Where <p>- PLATFORM_NAME is the name of the platform (e.g. Towed still imagery, Towed video imagery) <p>- CAMPAIGN_NAME is the name of a campaign (e.g. IN2017_V01) <p>- DEPLOYMENT_NAME is the name of the deployment or dive (e.g. IN2017_V01_A04_CAM01 is the voyage name, following by station number, followed by camera tow number) <p>- images/ is a directory containing video and still image files <p>- metadata.csv is a file containing position info and references to image files (e.g. timestamp, image_filename, depth from sensor on camera frame, altitude, CTD temperature, conductivity, pressure, dissolved oxygen, salinity, latitude, longitude and depth from USBL unless otherwise specified, comments) <p>We thank the Marine National Facility, the IN2017-V01 scientific party-led by the Chief Scientists L.K. Armand and P. O’Brien, MNF support staff and ASP crew members led by Capt. M. Watson for their help and support on board the RV Investigator. This dataset is published with the permission of the CEO, Geoscience Australia and according to MNF data policy.

A large multibeam echo sounder (MBES) dataset (710, 000 km2, inclusive of transit data) was acquired in the SE Indian Ocean to assist the search for Malaysia Airlines Flight 370 (MH370). Here, we present the results of a geomorphic analysis of this new data and compare with the Global Seafloor Geomorphic Features Map (GSFM) that is based on coarser resolution satellite-derived bathymetry data. The analyses show that abyssal plains and basins are significantly more rugged than their representation in the GSFM, with a 20% increase in the extent of hills and mountains. The new model also reveals four times more seamounts than presented in the GSFM, suggesting a greater number of these features than previously estimated for the broader region and indeed globally. This is important considering the potential ecological significance of these high-relief structures. Analyses of the new data also enabled knolls, fans, valleys, canyons, troughs and holes to be identified, doubling the number of discrete features mapped and revealing the true geodiversity of the deep ocean in this area. This high-resolution mapping of the seafloor also provides new insights into the geological evolution of the region, both in terms of structural, tectonic, and sedimentary processes. For example, sub-parallel ridges extend over approximately 20% of the area mapped and their form and alignment provide valuable insight into Southeast Indian Ridge seafloor spreading processes. Rifting is recorded along the Broken Ridge – Diamantina Escarpment, with rift blocks and well-bedded sedimentary bedrock exposures discernible down to 2,400 m water depth. Ocean floor sedimentary processes are represented in sediment mass transport features, especially along and north of Broken Ridge, and pockmarks (the finest-scale features mapped) south of Diamantina Trench. The new MBES data highlight the complexity of the search area and serve to demonstrate how little we know about the 85-90% of the ocean floor that has not been mapped with this technology. The availability of high-resolution and accurate maps of the ocean floor can clearly provide new insights into the Earth’s geological evolution, modern ocean floor processes, and the location of sites that are likely to have relatively high biodiversity. Poster presented the 2017 American Geophysical Union, Fall Meeting

Chapter 13 "Bathymetry" was provided by Kim Picard for Volume 3B of the 'Earth Observation Series' published by Australia and New Zealand CRC for Spatial Information. The final volume introduces the Australian environment in terms of geography, climate, biota, and resource management, then covers a broad range of application areas reliant on EO data. Specific case studies are included to demonstrate individual applications. Source - https://www.eoa.org.au/earth-observation-textbooks Recommended Chapter Citation: PIcard, K., Anstee, J.M., and Harrison, B.A. (2021). Bathymetry. Ch 13 in Earth Observation: Data, Processing and Applications. Volume 3B—Surface Waters. CRCSI, Melbourne. pp. 223–241. ISBN 978-0-6482278-5-4 Recommended Citation for Volume 3B: CRCSI (2020). Earth Observation: Data, Processing and Applications. Volume 3B: Applications—Surface Waters. (Eds. Harrison, B.A., Anstee, J.M., Dekker, A.G., King, E.A., Griffin, D.A., Mueller, N., Phinn, S.R., Kovacs, E., and Byrne, G.) CRCSI, Melbourne.