IMAS Metadata Catalogue
2020
Type of resources
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Years
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The Indonesian Throughflow (ITF) is connects the Pacific Ocean and the Indian Ocean in the tropics. The ITF plays an essential role in ocean circulation and regional climate: it hosts strong mixing that can change water-mass properties, influences the sea surface temperature in both oceans and affects the global ocean volume and heat transports. The ITF transports water properties across Indonesian Seas characterized by complex topography with most of the water entering through two main inflow straits, Makassar and Lifamatola straits, and exiting into the Indian Ocean through three main outflow straits, Ombai, Lombok and Timor straits. The ITF shows variabilities on different time scales, including decadal, interannual, seasonal and intra-seasonal. The ITF variability on intra-seasonal time scales is driven by remotely generated Kelvin and Rossby waves that propagate into the Indonesian Seas from the Indian Ocean and Pacific Ocean. This project focuses on the variability driven by Kelvin waves that propagate into Indonesian seas through three main outflow straits (Ombai, Lombok and Timor). We use a global ocean model and a high-resolution regional ITF model to characterize these variabilities at different depths and in different straits. We also use the mooring observations from the INSTANT program to validate the ocean models.
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Nitrogen stable isotope data from soil, leaf and spider samples collected from invaded, never invaded and eradicated islands around New Zealand's north island; and associated R code used to investigate the use of stable isotope analysis as a post-eradication ecosystem function assessment tool.
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The East Antarctic Ice Sheet (EAIS) is the largest source of potential sea-level rise, containing some 19 m of sea-level equivalent. One of the well-investigated regions in East Antarctica is Law Dome, which is a small independent ice cap situated to the west of Totten Ice Shelf. The ice cap is slow-moving, has a low melt-rate at the surface and moderate wind speeds, making it a useful study site for our investigations. Radar data from Investigating the Cryospheric Evolution of the Central Antarctic Plate (ICECAP) project has good coverage over this area. A new method is proposed for the estimation of attenuation rate from radar data which is mathematically modeled as a constrained regularised l2 minimization problem. In the proposed method, only radar data is required and the englacial reflectors are automatically detected from the radar data itself. A final product of 3D attenuation rates and 3D samples count is provided for the research community in this data set.
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Voyage IN2019_V04 contributed an additional 29,000 kms2 of seafloor survey data to the Coral Sea knowledge base. From this new bathymetric data individual seamounts have been extracted and have been classified to the Geoscience Australia Geomorphology Classification Scheme. This dataset contains two layers representing the classification layers- 1) Surface (Plain, Slope, Escarpment) and 2) fine scale Geomorphology of the seamount for the Fregetta Seamount. Ongoing research with this survey data will provide new insights into the detailed geomorphic shape and spatial relationships between adjacent seabed features. This information will be released in future publications to show the potential of how the scale of such seafloor data can be used for predictive habitat modelling when analysed with the biological data overlays.
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Trace element (TE) concentrations of juvenile Short-tailed Shearwaters collected on Great Dog Island, Tasmanian in 2017.
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Data for the project -Investigating the source of the high nitrate, low oxygen layer in the Leeuwin Current- is including in the file. The data include CTD data, ADCP data and Triaxus data from RV Investigator (Voyage IN2019_V03). Also the Sea Surface Height satellite data and CSIRO Atlas of Regional Seas (CARS) data are included as the supporting data. The MATLAB code including the code that calculate the rotated velocity and the transport of the EGC current in upper 300m including volume transport, salinity transport, heat transport and oxygen transport. The nitrate data from Triaxus is uncompleted and will be upload later with the code for calculating the nitrate transport.
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The prolonged rainfall reduction in South West Western Australia (SWWA) in recent decades has previously been reported to be unprecedented in the past 750 years. This rainfall reduction has reduced the water supply for both residents and agriculture in SWWA. However, the cause of this rainfall reduction is unclear. The relatively short length of the SWWA instrumental rainfall record limits long term studies of SWWA rainfall. In this study, SWWA rainfall is reconstructed based on a statistically significant negative correlation between SWWA rainfall and snowfall at Dome Summit South (DSS), East Antarctica. The 2000-year DSS snow accumulation record is used to reconstruct SWWA rainfall from 22 BCE to 2015 CE. With Cumulative Summation (CUSUM) analysis applied to the rainfall reconstruction, it is found that SWWA rainfall started to reduce around 1971 CE. This prolonged rainfall reduction is unprecedented during the past 750 years, but there have been two prior droughts of similar duration and intensity during the past 2000 years. Applying statistical techniques to compare the rainfall reconstruction with climate model simulations, it is found that greenhouse gases are likely to be the dominant driver of the SWWA rainfall drying trend after 1971 CE. This record describes the Honours Thesis [available for download in 'Online Resources' section of thsi record]. For the data generated by this project, see https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/d7d5ea56-f972-435d-b44b-44fea598150c
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The final lithospheric breakup of the Australian-Antarctic rift system remains controversial due to sparse geological constraints on the nature of the basement along the ocean-continent transition zones. We present new interpretations of multichannel seismic reflection transects, as well as new petrological data of dredged mantle rocks along the East Antarctic margin (Seamount B, offshore Terre Adélie). By combining both datasets, we show that a 50–100 km wide domain of cold (900°C), fertile subcontinental mantle was exhumed along the non-volcanic Antarctic margin. The dredged peridotites preserve characteristics similar to mantle xenoliths found in syn- to post-rift volcanism at the eastern end of the Australian margin (Victoria and Tasmania), indicating the sampling of a common fertile subcontinental mantle during rifting between Australia and Antarctica. Seamount B represents the initial stages of exhumation of cold subcontinental lithosphere along an ocean-continent transition during rifting. This thick mantle domain was likely affected by syn-rift melt impregnation at high-pressure (8 kbar), leading to the formation of plagioclase-pyroxenites. Overall, the combination of continental rifted blocks, a 50-100 km wide domain of volcanic-poor subcontinental mantle and (ultra)-slow spreading implies that ocean-continent transition zones along the Australian-Antarctic margins represent a recent analogue to ocean continent transition zones from the Jurassic Western Tethys. Additionally, evidence of syn-rift melt stagnation at high pressure suggests that magmatism along the Australian-Antarctic rifted margins was sufficient to form magnetic anomalies that can be used as isochrons despite their formation in lithosphere other than mature, steady-state ocean crust.
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Voyage IN2019_V04 contributed an additional 29,000 kms2 of seafloor survey data to the Coral Sea knowledge base. From this new bathymetric data individual seamounts have been extracted and have been classified to the Geoscience Australia Geomorphology Classification Scheme. This dataset contains two layers representing the classification layers- 1) Surface (Plain, Slope, Escarpment) and 2) fine scale Geomorphology of the seamount for the Calder Seamount. Ongoing research with this survey data will provide new insights into the detailed geomorphic shape and spatial relationships between adjacent seabed features. This information will be released in future publications to show the potential of how the scale of such seafloor data can be used for predictive habitat modelling when analysed with the biological data overlays.
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An aerial survey was conducted for giant kelp (Macrocystis pyrifera) on the east coast of Tasmania from Eddystone Point to Southeast Cape. This survey represents part of a series of similar surveys, with historic aerial surveys having been conducted in 1986 and 1999. The survey was conducted via light aircraft. Areas of visable Macrocystis pyrifera beds were marked on topographical land tenure maps using landmarks as references, and complimentary photo footage was collected.