  Electromagnetics has an important role to play in solving the next generation
of geoscience problems. These problems are multidisciplinary, complex, and
require collaboration. This is especially true at the base scientific level
where the underlying physical equations need to be solved, and data, associated
with physical experiments, need to be inverted. In this paper, we present
arguments for adopting an open-source methodology for geophysics and provide
some background about open-source software for electromagnetics. Immediate
benefits are the reduced time required to carry out research, being able to
collaborate, having reproducible results, and being able to disseminate results
quickly. To illustrate the use of an open-source methodology in
electromagnetics, we present two challenges. The first is to simulate data from
a time domain airborne system over a conductive plate buried in a more
resistive earth. The second is to jointly invert airborne TDEM and FDEM data
with ground TDEM. SimPEG, Simulation and Parameter Estimation in Geophysics,
(https://simpeg.xyz) is used for the open-source software. The figures in this
paper can be reproduced by downloading the Jupyter Notebooks we provide with
this paper (https://github.com/simpeg-research/oldenburg-2018-AEM). Access to
the source code allows the researcher to explore the simulations and inversions
by changing model and inversion parameters, plot fields and fluxes to gain
further insight about the EM phenomena, and solve a new research problem by
using open-source software as a base. By providing results in a manner that
allows others to reproduce, further explore, and even extend them, we hope to
demonstrate that an open-source paradigm has the potential to enable more rapid
progress of the geophysics community as a whole.
