EMP codes (emp1, emp2, and emp3): simulation of lightning EMP propagation and interaction with the ionosphere
    Copyright (C) 2014  Robert A. Marshall

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, version 3 of the License.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
    
    Personal note:

Please feel free to use this software in your own research, and adapt it to other uses. However, if you do so and publish results, please cite the following paper:

Marshall, R. A. (2012), An improved model of the lightning electromagnetic field interaction with the D-region ionosphere, J. Geophys. Res., 117, A03316, doi:10.1029/2011JA017408.