Point discharge current measurements beneath dust devils

We document for the first time observations of point discharge currents under dust devils using a novel compact sensor deployed in summer 2016 at the USDA-ARS Jornada Experimental Range in New Mexico, USA. A consistent signature is noted in about a dozen events seen over 40 days, with a positive current ramping up towards closest approach, switching to a decaying negative current as the devil recedes. The currents, induced on a small wire about 10 cm above the ground, correlate with dust devil intensity (pressure drop) and dust loading, and reached several hundred picoAmps.