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README.md

README.md

3D Magnetic modelling of ellipsoidal bodies

[D. T. Tomazella] (http://www.pinga-lab.org/people/tomazella.html)1, V. C. Oliveira Jr.1.

1Department of Geophysics, Observatório Nacional, Rio de Janeiro, RJ, Brazil.

This paper has been submitted for publication in [Geoscientific Model Development (GMD)]

####Abstract

Since the second half of the nineteenth century, a vast literature has been published on the magnetic modeling of uniformly magnetized ellipsoids. In this work, we present a integrated review about magnetic modeling of triaxial, prolate and oblate ellipsoids, with arbitrary orientation, with or without remanent magnetization and with both isotropic and anisotropic susceptibilities. We also bring a theoretical discussion regarding the commom value of isotropic susceptibility (0.1 SI), widely used by geoscientific community, and not often discussed, as the limit of which the self-demagnetization can be overlooked in magnetic modeling. Apparently, this value was obtained empirically and we propose an alternative way of determining its limit, based on previous knowledge of the shape and the maximum relative error allowed in the resultant magnetization. Jointly, we provide a set of routines capable of modeling the magnetic field produce by triaxial, prolate and oblate ellipsoidal bodies. These routines are written in Python language as part of the Fatiando a Terra package. Examples in this work show the friendly and easy usage of the program. Hence, we hope that this work can be useful both as educational tool (e.g. Potential Methods and rock magnetism) as to applied geophysics (e.g. high susceptibility bodies characterization) and are freely available at the link https://github.com/DiegoTaka/ellipsoid-magnetic for the geoscientific community.

Test with two triaxial ellipsoids modeled with the routines

This paper has been submitted for publication in [Geoscientific Model Development (GMD)]

Reproducing the results

You can download a copy of all the files in this repository by cloning the git repository:

git clone https://github.com/DiegoTaka/ellipsoid-magnetic.git

or click here to download a zip archive.

All source code used to generate the results and figures in the paper are in the code folder. The data used in this study is provided in data and the sources for the manuscript text and figures are in manuscript. See the README.md files in each directory for a full description.

The calculations and figure generation are all run inside Jupyter notebooks. You can view a static (non-executable) version of the notebooks in the nbviewer webservice:

http://nbviewer.jupyter.org/github.com/DiegoTaka/ellipsoid-magnetic

See sections below for instructions on executing the code.

Setting up your environment

You'll need a working Python 2.7 environment with all the standard scientific packages installed (numpy, scipy, matplotlib, etc). The easiest (and recommended) way to get this is to download and install the Anaconda Python distribution. Make sure you get the Python 2.7 version.

You'll also need to install the Fatiando a Terra library from GitHub. We used a development version defined by the commit hash [09cd37da986114a68c57c6a611271fc6cd22bde4] (https://github.com/fatiando/fatiando/tree/09cd37da986114a68c57c6a611271fc6cd22bde4). See the install instructions on the website.

Running the code

To execute the code in the Jupyter notebooks, you must first start the notebook server by going into the repository folder and running:

jupyter notebook

This will start the server and open your default web browser to the Jupyter interface. In the page, go into the code folder and select the notebook that you wish to view/run.

The notebook is divided cells (some have text while other have code). Each cell can be executed using Shift + Enter. Executing text cells does nothing and executing code cells runs the code and produces it's output. To execute the whole notebook, run all cells in order.

License

All source code is made available under a [BSD 3-clause] (http://choosealicense.com/licenses/bsd-3-clause/) license. You can freely use and modify the code, without warranty, so long as you provide attribution to the authors. See LICENSE.md for the full license text.

The manuscript text is not open source. The authors reserve the rights to the article content, which is currently submitted for publication in the [Geoscientific Model Development (GMD)]