Abstract

A holistic inversion algorithm has been developed for time-domain airborne electromagnetic (AEM) data. The algorithm simultaneously recovers a layered earth conductivity structure as well as unmeasured elements of the system geometry. It inverts a complete flight line of data in one inversion. This allows us to take advantage of the expected along-line continuity of conductivity and system geometry, which cannot be exploited when each sample is inverted independently. The conductivity and thickness of each layer and geometry variable is parameterised by the node coefficients of separate cubic-spline basis functions, which implicitly represent smooth continuous along line variations. Each of the cubic splines may have different node spacings that are chosen to adequately represent the expected scale length of lateral variability of conductivity and system geometry. The regularised inversion scheme is formulated to minimise an objective function comprised of data misfit, reference model misfit, and vertical and horizontal roughness terms. The minimisation is implemented via a gradient-based iterative scheme in which a sparse linearised system is solved by the conjugate gradient method within each iteration. The method has been applied to fixed-wing and helicopter AEM data. The results demonstrate that the method produces conductivity models that are geologically credible and consistent with downhole conductivity logs. They also show improved continuity and interpretability in comparison to sample by sample inversions. We found that the estimation of transmitter-receiver separation and receiver pitch geometry parameters was stabilised by the implicit along line continuity constraints.
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Product Type/Sub Type

nonGeographicDataset - External Publication - Conference Paper

Constraints

license
Creative Commons Attribution 3.0 Australia Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2009

Product Type

nonGeographicDataset

Topic Category

geoscientificInformation

Keywords

External Publication
Conference Paper
model
TEM
geophysics
AEM
Airborne Electromagnetics
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Lineage

Unknown

Digital Transfer Options

onLine

DISTRIBUTION Format

pdf

Distributor

Role
distributor
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Metadata File Identifier

a05f7892-db00-7506-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

Metadata Date Stamp

2008-10-29

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
Downloads
For information on acquiring this product,
please contact the Geoscience Australia Sales Centre via:

fax:
+61 2 6249 9960; or
phone:
1800 800 173 (within Australia);
 
+61 2 6249 9966 (outside Australia).

Please note that support hours are 9 am to 5 pm weekdays