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satellite

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    Gravity data measure small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This National Gravity Compilation 2019 tilt image is derived from the 2019 Australian National Gravity Grids A series. These gravity data were acquired under the project No. 202008. The grid has a cell size of 0.00417 degrees (approximately 435m). This gravity anomaly grid is derived from ground observations stored in the Australian National Gravity Database (ANGD) as at September 2019, supplemented with offshore data sourced from v28.1 of the Global Gravity grid developed using data from the Scripps Institution of Oceanography, the National Oceanic and Atmospheric Administration (NOAA), and National Geospatial-Intelligence Agency (NGA) at Scripps Institution of Oceanography, University of California San Diego. Out of the approximately 1.8 million gravity observations, nearly 1.4 million gravity stations in the ANGD with marina data were used to generate this grid. The ground gravity data used in this grid has been acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations from the 1940's to the present day. Station spacing varies from approximately 11 km down to less than 1 km, with major parts of the continent having station spacing between 2.5 and 7 km. Terrain corrections to gravity were calculated using both offshore bathymetry and onshore topography data. A tilt filter was then applied to the complete spherical cap Bouguer anomaly (A series) to produce this image covering Australia and its continental margins.

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    Gravity data measure small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This National Gravity Compilation 2019 includes airborne - CSCBA 0.5VD grid is derived from the 2019 Australian National Gravity Grids B series. These gravity data were acquired under the project No. 202008. The grid has a cell size of 0.00417 degrees (approximately 435m). This gravity anomaly grid is derived from ground observations stored in the Australian National Gravity Database (ANGD) as at September 2019, supplemented by offshore data sourced from v28.1 of the Global Gravity grid developed using data from the Scripps Institution of Oceanography, the National Oceanic and Atmospheric Administration (NOAA), and National Geospatial-Intelligence Agency (NGA) at Scripps Institution of Oceanography, University of California San Diego. Airborne gravity and gravity gradiometry data were also included to provide better resolution to areas where ground gravity data was not of a suitable quality. Out of the approximately 1.8 million gravity observations, nearly 1.4 million gravity stations in the ANGD together with Airborne Gravity surveys totaling 345,000 line km and 106,000 line km of Airborne Gravity Gradiometry were used to generate this grid. The ground and airborne gravity data used in this grid has been acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations from the 1940's to the present day. Station spacing varies from approximately 11 km down to less than 1 km, with major parts of the continent having station spacing between 2.5 and 7 km. Airborne surveys have a line spacing ranging from 0.5 km to 2.5 km. Terrain corrections to gravity were calculated using both offshore bathymetry and onshore topography data. A first vertical derivative was calculated by applying a fast Fourier transform (FFT) process to the complete spherical cap Bouguer anomaly grid of the 2019 Australian National Gravity Grids B series to produce this grid. The grid shows a half vertical derivative of the complete Bouguer anomalies (B series) over Australia and its continental margins.

  • This document describes a format of the AVNIR-2 (Advanced Bisible Near-Infrared Radiometer) products generaged by the ALOS Data Processing Subsystem.

  • ACRES acquired Landsat 7 satellite images showing bushfires in northern New South Wales in early October 2000. Fire fighters brought more than 80 bushfires under control, after more than 150,000ha of bushland were burnt. The image on the left was acquired on 2 June 2000. The second image shows the extent of the fires in the region from South West Rocks in the south to Grafton and the Clarence River in the North.

  • More than 100 bushfires raged across NSW from 25 December 2001 - January 8 2002, requiring over 20,000 regular and volunteer fire fighters and 85 aircraft. Vast stretches of forests were destroyed, including more than 60% of the Royal National Park. More than 11,000 people were evacuated from their homes and 560,000 hectares were burnt out. The image below was acquired from the SPOT satellite on 27 December 2001 by ACRES, Geoscience Australia. It is produced here as a mosaic of 8 SPOT scenes covering about 120km wide and 240km long, stretching from Wyong in the north to Jervis Bay in the south. Healthy vegetation shows as bright red, forest as dark red, ocean and lakes as dark blue, burnt areas as black and smoke as blue/white.

  • Normalising for atmospheric, land surface bidirectional reflectance distribution function (BRDF) and terrain illumination effects are essential in satellite data processing. It is important both for a single scene when the combination of land cover, sun, view angles and terrain slope angles create anisotropy and for multiple scenes in which the sun angle changes. Geoscience Australia (GA) is establishing a procedure to conduct physically based atmospheric BRDF and terrain illumination correction for moderate spatial resolution satellite imagery (10-100 m) such as Landsat using a coupled atmospheric and BRDF model. In particular, the method is not dependent on the image data, does not need extensive field data, can be applied equally to different environments and used with different sensors in a consistent way. Furthermore, the corrected surface reflectance derived using this method can be used to calibrate and cross-calibrate satellite sensors. More importantly, the normalized reflectance can be used for time series analysis to trace climate change and land cover variation using multiple sensors (including satellite, airborne and ground based). In this paper, we will describe the algorithm being progressed at GA. Preliminary results from the algorithm will be compared with ground based reflectance measurements for selected validation sites. The paper will also discuss how the environmental input data for the model, such as aerosol, water vapour and BRDF parameters are selected and applied.

  • Mapping of regolith materials at the regional and continental-scale for environmental, agricultural and resource exploration for is being advanced through a new generation of remote sensing technologies, particularly satellite remote sensing methods. The work has demonstrated the identification and classification of regolith materials and thickness indicators is essential to facilitate ongoing exploration in challenging regolith-dominated terrains, and that geochemical information about alteration chemistry associated with footprints of mineral systems can be acquired by analysing spectral ground response, particularly in short-wave infra-red.

  • Mapping and analysis of landscapes in Australia can now benefit from a continental mineral map coverage, helping to identify and characterise materials at the surface, with the recent release (August 2012) of the Satellite ASTER Geoscience Maps of Australia (http://c3dmm.csiro.au/Australia_ASTER/stage_1_geoscienceproductnotes.html). The new maps can provide mineralogical information on weathering, soils and regolith boundaries and compositions. The ASTER mosaic, made up of some ~3,500 60x60 km individual ASTER scenes, were produced by a multi-agency collaboration of Australian government partners. They represent the first of their kind: a continent-scale, public, web-accessible and GIS-compatible ASTER geoscience product suite. Led by CSIRO, Geoscience Australia along with several state government agencies, (including GSWA, GSQ, DMITRE and NTGS), have released 17 geoscientific products across the whole of Australia, with application to landscape analysis, environmental studies, mineral mapping and exploration, as well as soil-mapping and the agricultural sectors. Outcomes have included the formation of a platform for establishing national standards, geoscience product nomenclature, processing methods, accuracy assessments and traceable documentation. The ASTER bands are being used together with other complementary datasets (e.g. terrain indices, gamma-ray radiometrics) to build statistical predictive models on surface regolith geochemistry. This study is a preliminary investigation and assessment of how to use the new products for geomorphic applications, particularly landscape analysis and characterisation.

  • The Otway-Sorell study is part of Infoterra's Global Seeps programme - a multi-phase two year exploration programme to create the definitive offshore seeps database for the worldwide exploration industry. The Otway-Sorell Basin study includes interpretations by Infoterra and Geoscience Australia that correlate multiple seep clusters with regional seismic and gravity datasets. The study provides exciting new evidence on the oil prospectivity of this offshore region.

  • Geoscience Australia acquires satellite imagery from a range of Earth observation satellites. This poster focuses on Australian States and Territories and various satellite applications.