From 1 - 10 / 409
  • Digital Elevation Model data record the terrain height variations from the processed point-located data recorded on an airborne geophysical survey.  The aircraft altimeter data records the height of the aircraft above the ground and the aircraft GPS records the height of the aircraft above the ellipsoid.  Subtracting the two values enables the height of the terrain beneath the aircraft relative to the ellipsoid to be calculated.  This ellipsoidal terrain height is corrected for the variation between the ellipsoid and the geoid (the n-value correction) to produce terrain heights relative to sea level.

  • Total magnetic intensity data measures variations in the intensity of the Earth's magnetic filed caused by the contrasting content of rock-forming minerals in the Earth's crust. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

  • The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

  • Total magnetic intensity data measures variations in the intensity of the Earth's magnetic filed caused by the contrasting content of rock-forming minerals in the Earth's crust. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

  • Digital Elevation Model data record the terrain height variations from the processed point-located data recorded on an airborne geophysical survey.  The aircraft altimeter data records the height of the aircraft above the ground and the aircraft GPS records the height of the aircraft above the ellipsoid.  Subtracting the two values enables the height of the terrain beneath the aircraft relative to the ellipsoid to be calculated.  This ellipsoidal terrain height is corrected for the variation between the ellipsoid and the geoid (the n-value correction) to produce terrain heights relative to sea level.

  • Total magnetic intensity data measures variations in the intensity of the Earth's magnetic filed caused by the contrasting content of rock-forming minerals in the Earth's crust. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

  • Survey conducted by the Commonwealth Government or State/Territory Geological Survey (or equivalent) collecting airborne geophysical data

  • Survey conducted by the Commonwealth Government or State/Territory Geological Survey (or equivalent) collecting airborne geophysical data

  • We measured the light absorption properties of two naturally occurring Australian hydrocarbon oils, a Gippsland light crude oil and a North West Shelf light condensate. Using these results in conjunction with estimated sensor environmental noise thresholds, the theoretical minimum limit of detectability of each oil type (as a function of oil thickness) was calculated for both the hyperspectral HYMAP and multispectral Quickbird sensors. The Gippsland crude oil is discernable at layer thickness of 20 micro metres or more in the Quickbird green channel. The HYMAP sensor was found to be theoretically capable of detecting a layer of Gippsland crude oil with a thickness of 10 micro metres in approximately six sensor channels. By contrast, the North West Shelf light condensate was not able to be detected by either sensor for any thickness up to 200 icro metres. Optical remote sensing is therefore not applicable for detecting diagnostic absorption features associated with this light condensate oil type, which is considered representative for the prospective Australian Northwest Shelf area. We conclude that oil type is critical to the applicability of optical remote sensing for natural oil slick detection and identification. We recommend that a sensor- and oil-specific sensitivity study should be conducted prior to applying optical remote sensors for oil exploration. The oil optical properties were obtained using two different laboratory methods, a reflectance-based approach and transmittance-based approach. The reflectance-based approach was relatively complex to implement, but was chosen in order to replicate as closely as possible real world remote sensing measurement conditions of an oil film on water. The transmittance-based approach, based upon standard laboratory spectrophotometric measurements was found to generate results in good agreement with the reflectance-based approach. Therefore, for future oil- and sensor-specific sensitivity studies, we recommend the relatively accessible transmittance-based approach, which is detailed in this paper.