Introduction

The Cole-Cole decomposition tools provide a set of Python programs to fit electrical complex resistivity spectra (or Spectral Induced Polarisation, SIP, spectra/signatures) using a Cole-Cole decomposition scheme (see section Theory of SIP models for an theoretical overview of the implemented methods). This also includes the popular Debye decomposition scheme. In addition to the independent decomposition of one or more spectra, a smoothing regularization can be applied between multiple spectra for cases of time-lapse data where only smooth changes between subsequent measurements in a time series are expected.

The installation for Windows and Linux is described in the section Installation, and the section Getting Started provides first usage instructions.

Please note that the Cole-Cole decomposition is, at the moment, only implemented for the resistivity case. For the conductivity formulation, only the Debye decompositon (c = 1) is implemented.

If you are looking for a classic Cole-Cole fit using only one or two terms, have a look at https://github.com/m-weigand/Cole-Cole-fit.

Two primary decomposition programs are provided:

  • ccd_single fits an arbitrary number of SIP spectra without any kind of regularization between the spectra.

  • ccd_time fits an arbitrary number of time-lapse SIP spectra with a regularization on the time axis (separate regularization parameters for \rho_0 and the chargeabilities m_i)

See Fit Routines for a complete list of the provided programs, and detailed description of the input parameters.

Each front-end is accompanied by a post processing tool (ddps.py, ddpt.py) which allows various analysis and postprocessing steps to be applied on inversion results. This includes filtering and plotting routines.

This package depends on two additional python packages, sip_models and geccoinv, developed in separate git repositories. They are, however, integral components of the Cole-Cole decomposition routines.

Separate repositories are maintained for sip_models, geccoinv and ccd_tools:

Feedback, bug reports, and general advice is always welcome. Please use the issue tracker on the github pages for communication (https://github.com/m-weigand/ccd_tools/). Before you report a bug, make sure to search the existing bugs (issues) for relevant items. Also, make sure to include all necessary information to reproduce reported bugs. A small example, including data set and batch files to trigger the bug, is always helpful!

The Cole-Cole decomposition tools (including the packages “sip_models” and “geccoinv”) are licenced under the GPL 3 or later (https://www.gnu.org/licenses/licenses.html#GPL).

Note

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