Metadata record for data from ASAC Project 2315 See the link below for public details on this project. ---- Public Summary from Project ---- Project title: EFFECTS OF THE MODULATION OF THE SURFACE SHEAR STRESS BY THE WAVE FIELD IN A MODEL OF THE SOUTHERN OCEAN This project will investigate the sensitivity of currents and tracer properties in a non-eddy-resolving ocean general circulation model to a formulation of the surface shear stress which takes account of surface air and water velocities induced by the ocean wave field. These velocities will be computed accurately from archived model wave fields and also parameterised from wind and current velocities. From the abstract of the reference paper: We present a basic analysis of the propagation of deep-water waves on curved trajectories. The key feature is that the amplitude of the wave varies transversely, and may in the generation of a short-crested of high amplitude. The properties of there waves are explored, and it is suggested that they are a model for extreme waves, which may violate the conditions under which the classical distribution of wave heights has been derived. In their full development, they are manifested a generic rouge waves. From the 2002/2003 season: The aim of this project was to investigate mode water formation south of Australia in an ocean general circulation model (OGCM). The grant monies were used to employ a numerical modeller (Dr Harun Rashid) who became familiar with the curvilinear grid version of the modular ocean model No. 1 (MOM1) model developed by Ross Murray, and then applied the model with high resolution (0.6 x 0.4 degree) in the region south-west of Tasmania, where recent observations obtained on Franklin cruise (Fr9801) to the west of the SR3 section, indicated that mode water was being formed. The model was found to be inadequate to the task of simulating the formation region, as also were the OCCAM simulations, which have been downloaded and compared with the MOM1 simulations. The reason for this negative conclusion was sought during the course of the project, and it was determined that in the OGCMs: (a) the westward advection south of Tasmania was too strong, and (b) the coefficients of lateral diffusion at deeper levels in the water column were too large. The cruise data, which were investigated by Paul Barker as part of his Ph.D. thesis, indicated that the region of water mass formation south-west of Tasmania, occurs over the depth range of the mode water and the intermediate water and through to the upper circumpolar deep water (300 - 1500 m). It was deduced that the formation mechanism involves the mixing of two source waters, one from the Tasman Sea, the other from the Southern Ocean, which combine to form Tasmanian Subantarctic Mode Water (TSAMW), Tasmanian Intermediate Water (TIW), and probably Tasmanian Upper Circumpolar Deep Water (TUCDW). The dynamical reason for the location of the water mass formation appears to be the existence of a saddlepoint in the streamflow (at which the mean horizontal velocity is zero) over the depth range (300 - 1500m), due to the gyral circulation of the South Australian Basin to the west and the retroflection of the Tasman Outflow to the east. In order to represent this physics, it is very important to simulate correctly the advection at each level in the water column This is not done by the OGCMs, but in the course of the project, the importance of advection on the position of the saddlepoint was demonstrated in a series of simulations using the transports obtained from a simple Sverdrup transport model. The modelled fields were then used to advect temperature and salinity at each level with lateral diffusion coefficients adjusted for the best match with the observed property fields. These 'best fit' lateral diffusion coefficients in the deeper levels were found to be much smaller than those used in the OGCMs. The mechanism outlined above is distinct from that in earlier work in which mode water formation was interpreted using Ekman rather then gyral dynamics, without attention being given to the deeper levels. A simple balance shows that the gyral current is of similar magnitude to the Ekman current in the surface layer, and below the surface layer the Ekman current is absent. Recently (December 2003) Ross Murray has indicated that the problem addressed in this 2002-2003 grant can be revisited, using a 20 year simulation he is obtaining with TPAC NCEP II forcing on a resolution of 1/8 degree. It is our intention to work with Ross in February 2004 to see if the problems detailed above can be overcome, so that the ocean physics in this important water mass formation region can be simulated.

Scanned copy of an acoustics log from Casey Station. Data were collected during 1997. There is no accompanying information to go with the log.

From December 2014 to February 2015, Geoscience Australia conducted a multibeam sonar survey (GA-0348) of the coastal waters around Casey station and the adjacent Windmill Islands. The survey utilised GA's Kongsberg EM3002D multibeam echosounder, motion reference unit and C-Nav differential GPS system mounted on the Australian Antarctic Division's (AAD) science workboat the Howard Burton. The survey was a collaborative project between GA, the AAD and the Royal Australian Navy (RAN). During the survey a total of approximately 27.3 square kilometres of multibeam bathymetry, backscatter and water-column data were collected, extending coverage of a RAN multibeam survey (survey number HI545) conducted the previous season (approximately 7 square kilometres). The regions covered extended seaward of Newcomb Bay and Clark Peninsula northwest of Casey Station, and seaward of Shirley and Beall Islands to the southwest. Complimentary datasets were also collected, including 18 drop video deployments to assess the benthic ecosystem composition and 39 sediment samples to ground-truth the seafloor substrate. Macroalgae spectral analyses were also collected to develop a spectral library for possible future satellite bathymetry investigations. The new high-resolution bathymetric grid (1 metre resolution) reveals seafloor features in the Casey area in unprecedented detail.

In January 2005 a multi-parametric international experiment was conducted that encompassed both Deception Island and its surrounding waters. This experiment used as main platforms the Spanish Oceanographic vessel 'Hesperides', the Spanish Scientific Antarctic base 'Gabriel de Castilla' at Deception Island and four temporary camps deployed on the volcanic island. This experiment allowed us to record active seismic signals on a large network of seismic stations that were deployed both on land and on the seafloor. In addition other geophysical data were acquired, such as: bathymetric high precision multi-beam data, and gravimetric and magnetic profiles. The gravimeter BELL AEROSPACE-TEXTRON BGM-3 (at the present Lockheed Martin Federal Systems) is an acquisition system that can be used both in aerial and marine vehicles. The system has a sensor mounted in a gyro-stabilized platform. This system is composed of a gravimeter sensor, the stabilized platform and an acquisition system. Raw data are recorded and processed in a computer HP-486/50 using the own BGM software providing two types of data, raw and previously analyzed data. Acquired raw data are presented in the following format: $PRAWGRV, Day, Hour, Flag, Mean Value,. However, the analyzed data are transformed into: $PHESGRV, Day, Hour, Flag, Mean Value, Value GRS67, Eotvos Correction, sinv, sinv. Potential 'flag' values associated to the sensor status are: 0: normal, 2: error, 5: starting.

In January 2005 a multi-parametric international experiment was conducted that encompassed both Deception Island and its surrounding waters. This experiment used as main platforms the Spanish Oceanographic vessel 'Hesperides', the Spanish Scientific Antarctic base 'Gabriel de Castilla' at Deception Island and four temporary camps deployed on the volcanic island. This experiment allowed us to record active seismic signals on a large network of seismic stations that were deployed both on land and on the seafloor. In addition other geophysical data were acquired, such as: bathymetric high precision multi-beam data, and gravimetric and magnetic profiles. During the whole period of the experiment a multi-beam sounding EM120 was used to perform bathymetric surveys. The characteristic of this sensor permitted to reach up to 11.000 m b.s.l. In table 2 we provide some of its main characteristics. During the experiment different bathymetric profiles were performed with this equipment outside of Port Foster. Some of these images already have provide an accurate vision of the region, and were used to estimate the real size of the water column locate below each shoot. Additional information of these data could be found in the Lamont-Doherty Earth Observatory at IEDA Marine Geoscience Data System (http://www.marine-geo.org/). It is possible to access the summary of downloads that were made of these data and documents at http://www.marine-geo.org/about/downloadreport/person/Ibanez_Jesus/2016A.

This dataset contains bathymetry (water depth), ship's heading, ship's speed and position data collected during the Nella Dan Voyage 4 1987-88. This was the Nella Dan's final voyage. Some marine science was carried out en route to Macquarie Island from Hobart. Data are available online from the Australian Antarctic Division Data Centre web page (see Related URL below). For further information, see the Marine Science Support Voyage Report at the Related URL below.

This dataset contains bathymetry (water depth), ship's heading, ship's speed and position data collected during the Nella Dan Voyage 7 1986-87. This was a marine science voyage which also visited Davis. Data are available online via the Australian Antarctic Division Data Centre web page (see Related URL below). For further information, see the Marine Science Support Voyage Report at the Related URL below.

A database containing sounding data around Macquarie Island. Track line data for each data source is included.

The RAN Australian Hydrographic Service conducted hydrographic survey HI176 at Macquarie Island in December 1993. The main survey area was adjacent to the north-east coast between North Head and The Nuggets. Survey lines were also followed part way down the west coast of the island and in the vicinity of Judge and Clerk Islets and Bishop and Clerk Islets. The survey dataset, which includes metadata, was provided to the Australian Antarctic Data Centre by the Australian Hydrographic Office and is available for download from a Related URL in this metadata record. The survey was lead by LT A.J.Withers. The data are not suitable for navigation.

CAWCR Hindcast* and ECMWF ERA-5** model predictions of wave spectral properties (wave height and period) and corresponding observed data from ACE. Observations are mapped to model grids. Quality control is applied, i.e. cells with a number of points less than 5 and/or with high data variation (Standard Deviation/Mean greater than 0.2) are eliminated. Files are named as follows: WaMoS_vs_CAWCR_Hs.mat WaMoS_vs_CAWCR_Tm.mat WaMoS_vs_ERA5_Hs.mat WaMoS_vs_ERA5_Tp.mat In each file, columns show Latitude (deg.), Longitude (deg.), Time (number of days from January 0, 0000), Model Parameters (Hs, Tp or Tm) and Observed Parameters (Hs, Tp or Tm), respectively. Hs denotes significant wave height in meters, Tp is peak wave period in seconds and Tm is mean wave period based on the first moment of wave spectrum in seconds. The MATLAB file, WaMoSvsModel_FigurePlot.m, can be used to visualise the results. The files dscatter.m and polyfix.m are functions used in the MATLAB script. A sample figure (SampleFigure.png) is also included for users’ reference. * Durrant, T., Greenslade, D., Hemer, M. and Trenham, C., 2014. A global wave hindcast focussed on the Central and South Pacific (Vol. 40, No. 9, pp. 1917-1941). ** Copernicus Climate Change Service (C3S) (2017): ERA5: Fifth generation of ECMWF atmospheric reanalyses of the global climate . Copernicus Climate Change Service Climate Data Store (CDS), Dec. 12, 2018.