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GEOMACS (Geological and Oceanographic Model of Australia's Continental Shelf) Trimmed meanNote: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2. Dataset citationANZLIC unique identifier: ANZCW0703015155 Title: GEOMACS (Geological and Oceanographic Model of Australia's Continental Shelf) Trimmed mean CustodianCustodian: Geoscience Australia Jurisdiction: Australia DescriptionAbstract: Geoscience Australia's GEOMACS model was utilised to produce hindcast hourly time series of continental shelf (~20 - 300 m depth) bed shear stress (unit of measure: Pascal, Pa) on a 0.1 degree grid covering the period March 1997 to February 2008 (inclusive). The hindcast data represents the combined contribution to the bed shear stress by waves, tides, wind and densitydriven circulation. The trimmed mean is simply the arithmetic mean calculated excluding a percentage of the highest and lowest values in the distribution. On this occasion the highest and lowest 25% of model observations were excluded for the calculation. The geometric mean was used alongside the trimmed mean to provide a more robust representation of the bulk of the values than the arithmetic mean would have provided (Hughes & Harris 2008). ANZLIC search words:
Spatial domain:
Geographic extent name: AUSTRALIA EXCLUDING EXTERNAL TERRITORIES - AUS - Australia - Australia Geographic extent polygon: 110 -7, 156 -7, 156 -44, 110 -44, 110 -7, Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register
Data currencyBeginning date: 2008-07-24 Ending date: 2008-07-24 Dataset statusProgress: Complete Maintenance and update frequency: Not Known Access
Access constraints: This material is released under the Creative Commons Attribution 3.0 Australia Licence. Free Data DownloadData qualityLineage: The Geological and Oceanographic Model of Australia?s Territory (GEOMAT- Harris et al., 2000) developed at Geoscience Australia provides maps indicative of the Australian seabed exposure. GEOMAT v.1 proposed a classification of the Australian under water territory based on sediment mobility induced by distinct processes such as tidal currents and gravity waves (Porter-Smith et al., 2004). GEOMAT v.2 (GEOMACS) proposed an improved classification of the continental shelf area based on a seabed exposure index (Hemer, 2006). The seabed exposure index was derived from the statistical distribution of the sediment transport rate, which reflected the strength and frequency of the combined wave-current bed shear stress. The bed shear stress was derived from a bottom boundary layer model (SEDTRANS - Li and Amos, 2001), which integrated the combined action of tidal currents (Egbert et al., 1994), oceanic currents (OCCAM; Webb et al., 1998), and gravity waves (AUSWAM - Greenslade, 2001) over a given mean sediment fraction (MARS; Geoscience Australia, 2006). Positional accuracy: The dataset is estimated on a 0.1deg grid resolution. Attribute accuracy: Output from mathematical model. No direct field observations. The GEOMACS model does not include the effects of wave breaking and refraction/diffraction or non-linear shallow-water effects on the tide, therefore the model is not considered useful in <10 m water depth, and in many regions in <30 m water depth; depending on the dominant wave period, tidal range and bathymetric complexity (Hughes & Harris 2008). Conversely, seabed disturbance produced by the wave, tide and current input variables appears not to extend beyond 300 m depth. The temporal domain includes 11 years and therefore contains limited information on events with long return intervals at specific locations, e.g. tropical cyclones (Hughes & Harris 2008). Logical Consistency: All model outputs data have been visually checked for artefacts and spurious data. Tests conducted to ensure data are reliable and valid. Completeness: Completed Contact information
Metadata informationMetadata date: 2013-03-08 Additional metadataMetadata reference XHTML: http://www.ga.gov.au/meta/ANZCW0703015155.html Metadata reference XML: http://www.ga.gov.au/meta/ANZCW0703015155.xml Egbert, G.D., Bennett, A.F., and Foreman, M.G.G., 1994. TOPEX/POSEIDON tides estimated using a global inverse mode. Journal of Geophysical Research 99, 24821-24852. Greenslade, D.J.M., 2001. The Assimilation of ERS-2 Significant Wave Height Data in the Australian region. Journal of Marine Systems 28, 141-160. Harris, P. T., Smith, R., Anderson, O., Coleman, R., and Greenslade, D., 2000. GEOMAT ? modelling of continental shelf sediment mobility in support of Australia?s regional marine planning process. Australian Geological Survey Organisation Record 2000/41. Geoscience Australia, Canberra. 53pp. Hemer, M.A., 2006. The magnitude and frequency of combined flow bed shear stress as a measure of exposure on the Australian continental shelf. Continental Shelf Research 26, 1258-1280. Hughes, M., Harris, P. T., 2008. Progress Report on Disturbance Task C1, Surrogates Program, Marine Biodiversity Hub. Geoscience Australia, Canberra. Li, M.Z., and Amos, C.L., 2001. SEDTRANS96: the upgraded and better calibrated sediment transport model for continental shelves. Computers and Geosciences 27, 619-645. Porter_Smith, R., Harris, P.T., Anderson, O., Coleman, R., Greenslade, D.J.M., and Jenkins, C.J., 2004. Classification of the Australian continental shelf based on predicted sediment threshold exceedance from tidal currents and swell waves. Marine Geology 211, 1-20. Webb, D.J., Cuevas, B.A., and Coward, A.C., 1998. The first main run of the OCCAM global ocean model. Internal Report of James Rennell Division, Southampton Oceanography Centre, UK. 50pp. See also:http://www.noc.soton.ac.uk/JRD/OCCAM. Authors:Hughes, M.G. Harris, P.T. |
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