Fortran source code
Coil configurations

AarhusInv is our high performance modeling and inversion code supporting a variety of geophysical data types, configurations, and source-receiver types. AarhusInv provides efficient and high precision modeling and inversion of any airborne EM configuration and ground based TEM, GCM, DC, MRS and time domain IP configurations. Also sources and receives in ground are supported in AarhusInv. For airborne EM, key system parameters of the various AEM systems can be modeled in AarhusInv. For example: Pitch and roll bird moments, width of the individual time gates, system low pass filters, front gate, transmitter and receiver height, etc. For the IP part the full IP decade curves are modeled with a Cole-Cole model.

In general AarhusInv uses a locally 1D l model description. In the inversion phase the models are constrained together forming a 3D-model space. For DC and IP a full 2D solution is available as well.

The base of the inversion scheme in ArhusInv is an iterative solver. The inversion supports:

  • Layer, smooth and sharp model description
  • Model description in a regular 3D grid with scatted data records
  • Lateral and vertical constraining of any model parameters
  • Prior constraints on any model parameters
  • Joint or constraints inversion of different data types and methods
  • Depth of investigation estimates (DOI)

Among other things the high performance is obtained by an efficient code parallelization, iterative sparse matrix solvers in the inversion phase, and  sparse matrix data stored  for efficient memory handling. AarhusInv is therefore capable of handling vary large airborne EM surveys in a single spatial constraint model setup (SCI)  and utilizes multi core CPU’s in a very efficient way.

User interfaces
The AarhusInv program is a stand-alone command-prompt executable, written in Fortan. It runs on Windows platforms. AarhusInv is available in a 64-bit and a 32-bit version. We provide AarhusInv as freeware for non-commercial purposes. 

The EMMA program (freeware) is a user interface to AarhusInv for calculating EM and VES forward responses. The SPIA program is developed for processing and inversion of ground based TEM and VES data. Aarhus Workbench handles processing and inversion of airborne EM, GCM and ERT/IP data.

Download and manual

The software is a full version with no limitations. The program is free to use for non-commercial purposes. The HydroGeophysics Group, Aarhus University, Denmark does not take responsibility for any loss or inconvenience due to the use of AarhusInv.  Distribution of the program is not allowed unless permitted by the authors. If AarhusInv is included in another program or a user interface is added, this program must be freeware as well and the authors credited.

Although AarhusInv is free to use for non-commercial purposes you need to sign and return a registration form to receive AarhusInv. Registration form, pdf

AarhusInv main reference
An overview of a highly versatile forward and stable inverse algorithm for airborne, ground-based and borehole electromagnetic and electric data, Exploration Geophysics, 2014, Auken, E., Christiansen, A. V., Kirkegaard, C., Fiandaca, G., Schamper, C., Behroozmand, A. A., Binley, A., Nielsen, E., Effersø, F., Christensen, N. B., Sørensen, K. I., Foged, N., and Vignoli, G. pdf

Manual - pdf
File examples - zip

Key methodological references

Sharp Spatially Constrained Inversion (sSCI) with applications to transient electromagnetic data, Geophysical Prospecting, 2014, Vignoli, G., Fiandaca, G., Christiansen, A. V., Kirkegaard, C., and Auken, E.

A parallel, scalable and memory efficient inversion code for very large scale airborne EM surveys,
Geophysical Prospecting, 2014, Kirkegaard, C. and Auken, E.

A global measure for depth of investigation, Geophysics, 77, 2012, Christiansen, A. V. and Auken, E. pdf

Quasi-3D modeling of airborne TEM data by Spatially Constrained Inversion,
Geophysics, 73, 2008, Viezzoli, A., Christiansen, A. V., Auken, E., and Sørensen, K. I. pdf

Piecewise 1D Laterally Constrained Inversion of resistivity data, Geophysical Prospecting, 53, 2005, Auken, E., Christiansen, A. V., Jacobsen, B. H., Foged, N., and Sørensen, K. I. pdf

Layered and laterally constrained 2D inversion of resistivity data, Geophysics, 69, 2004, Auken, E. and Christiansen, A. V. pdf

Inversion with mixed datatypes
Mutually and laterally constrained inversion of CVES and TEM data - A case study, Near Surface Geophysics, 5, 2007, Christiansen, A. V., Auken, E., Foged, N., and Sørensen, K. I. pdf

Combination of 1D laterally constrained inversion and 2D smooth inversion of resistivity data with a priori data from boreholes, Near Surface Geophysics, 3, 2005, Wisén, R., Auken, E., and Dahlin, T. pdf

Laterally and Mutually Constrained Inversion of Surface Wave Seismic Data and Resistivity Data, Journal of Environmental & Engineering Geophysics, 10, 2005, Wisén, R. and Christiansen, A. V. pdf

Airborne EM
Coil response inversion for very early time modelling of helicopter-borne time-domain electromagnetic data and mapping of near-surface geological layers, Geophysical Prospecting, 62, 2014, Schamper, C., Auken, E., and Sørensen, K. I. pdf

Spatially constrained inversion for quasi 3D modelling of airborne electromagnetic data - an application for environmental assessment in the Lower Murray Region of South Australia,
Exploration Geophysics, 40, 2009, Viezzoli, A., Auken, E., and Munday, T. pdf

Laterally constrained inversion of helicopter-borne frequency-domain electromagnetic data,
Journal of Applied Geophysics, 67, 2009, Siemon, B., Auken, E., and Christiansen, A. V. pdf

Induced polarization(IP)
Resolving spectral information from time domain induced polarization data through 2-D inversion 
Geophysical Journal International, 192, 631-646, 2013, Fiandaca, G., Ramm, J., Binley, A., Gazoty, A., Christiansen, A. V., and Auken, E. pdf

Time-domain induced polarization: Full-decay forward modeling and 1D laterally constrained inversion of Cole-Cole parameters, Geophysics, 77, 23-4-2012, Fiandaca, G., Auken, E., Gazoty, A., and Christiansen, A. V. pdf

Magnetic resonance sounding (MRS)
Efficient full decay inversion of MRS data with a stretched-exponential approximation of the T2* distribution, Geophysical Journal International, 190, 2012, Behroozmand, A. A., Auken, E., Fiandaca, G., Christiansen, A. V., and Christensen, N. B. pdf

Improvement in MRS parameter estimation by joint and laterally constrained inversion of MRS and TEM data, Geophysics, 74, 2012, Behroozmand, A. A., Auken, E., Fiandaca, G., and Christiansen, A. V. pdf