Aarhus Geophysics has developed a unique module for handling of SkyTEM data. The module is used both to get an overview of the data and performance of the instruments in the field and to process and invert SkyTEM data in the office.

Main Features

• An efficient environment optimized for production.
• Integrated with GIS and data management for handling and processing of very large datasets.
• Inversion using Laterally or Spatially Constrained Inversion with parameterized or smooth models.
• Integrated with the Aarhus Workbench environment making it fast to produce thematic maps and cross sections from the inverted models.

Processing SkyTEM data involves an automatic part and a manual part. The automatic part has the following steps:

• Import of the raw voltage and navigation data into the GERDA database and automatic conversion of GPS data to the local UTM coordinate system.
• Removal of tree top reflections from the altitude data using a recursive filtering technique.
• Automatic processing and filtering of the voltage data. Coupled data are removed from the raw data stacks. Data which are significantly influenced by noise after the averaging are removed.

After the automatic processing data can either we inverted or the processing can be further refined. During the manual refinement sounding decays are inspected and noisy or coupled data not already culled during the automatic processing are removed. This ensures high quality processing.

Inversion

The inversion of the data is, optimally, done twice – the first time for further refinement of the processing, the second time for the final output. Typically the Laterally Constrained Inversion methodology is used. This involves the following steps:

• A first inversion using smooth models. Noisy data, which has not been culled during data processing and which can not be fitted are removed – either automaticially or manually.
• A second and final inversion using either smooth models and/or models with a discrete number of layers – typically 4 or 5. This choice is dependent on the survey. Typically few layer inversion are used for for mapping sharp boundaries like clay or saltwater interfaces. Smooth inversion are used for mapping complex geological structures.

The inversion algorithm has the altitude as a softly constrained inversion parameter. The a priori altitude is determined from the filtered laser altitude data. If the voltage data includes x-component decays the tilt of the transmitter frame is included as an inversion parameter as well.

The data inversion module is described in greater detail under Inversion module.

More Information

More information on the SkyTEM processing module can be obtained from:

• Guide to processing and inversion of SkyTEM data (pdf)
• Information about the SkyTEM - go to SkyTEM aps homepage.

Licensing

The SkyTEM processing and inversion system is a module of the Aarhus Workbench program. Recommended setups are listed on the Licensing page.