Modeling the Formation of Electric and Magnetic Fields in Dust Devils

Abstract Dust devils are a weather phenomenon in which lofted particles become charged through triboelectrification, generating electromagnetic fields. These pose hazards for electronic equipment and affect biological systems. We present a new methodology for simulating the formation of electromagnetic fields within and near dust devils. Starting from an approximation of planar circular motion and physical laws defining field generation from charged particles, a dust devil model is developed based upon observation and measurements. Simulated electromagnetic fields from a 7 m diameter event match measured fields. The only in situ measurements of electromagnetic fields within a dust devil record an electric field of −4.3 kVm −1 50 m from the center of the dust devil and a central magnetic field of 0.4 nT. Our simulation using 10 6 superparticles yields 0.16 nT at the center and −3.2 kVm −1 50 m distant, indicating that the model is effective. Analysis shows the results are most sensitive to poorly understood parameters, such as the grain size distribution through the height of the dust devil, and the azimuthal distribution of dust in the event. These are crucial areas for targeted future measurements. The model not only enables simulation of dust devils without supporting experimental data but also allows key properties to be inferred when point measurements are available, this is particularly important given the scarcity of experimental data. The simulation's modular structure means it is readily adapted to simulate dust devils with differing properties, in different environments, or when more experimental data become available.