Quantifying Electric Field Effects on Coarse Dust Settling in a Controlled Dust Plume Environment

Global climate models underpredict the atmospheric mass of coarse-mode dust particles (diameter >5 µm), accounting for only ~50% of observed concentrations. One potential source of this discrepancy is the omission of electrostatic (Coulomb) forces, which can influence particle settling velocities. Observational and modeling studies suggest that electric fields generated within dust plumes—such as those produced by Saharan dust storms and uplifted into the Saharan Air Layer—can significantly alter the transport and deposition behavior of particles in the coarse-mode.

To investigate these effects under controlled conditions, we use a 1.6-meter-tall humidity-controlled stainless steel cloud chamber, repurposed to generate vertically suspended dust plumes. This setup enables measurement of ion production via triboelectric interactions, particle charge polarity as a function of size, and the electric field strengths resulting from vertical charge separation between particle layers. The experiment also quantifies the rate of ion attachment to particles across fine and coarse size modes.

Future work will use these measurements to quantify the development, intensity, and duration of electric fields generated during initial dust transport. The resulting data will inform parameterizations of dust dynamics in large-scale atmospheric models to better constrain coarse particle residence times and distribution.