The Sensor That May Help Battle Climate Change
Dust aerosols—which can lead to a cooling effect on climate—are predominantly lifted into the air by saltation, a process by which sand particles are dragged by wind and bounce along the surface, ejecting the smaller, harder to lift, dust particles (aerosols) into the air. Saltation lifts dust in blowing sand, dusty plumes, dust devils, and dust storms. Moreover, on Earth, Mars, and beyond saltation is an important geological process that leads to the formation of sand dunes and the erosion of geological features.
Various studies have shown that on Earth, saltation and dusty phenomena can produce electric fields (E-fields) in excess of 100 kV/m. Theory and laboratory experiments suggest that these E-fields reduce the wind stress necessary to initiate saltation, thereby increasing the concentration of saltating particles at a given wind speed. Moreover, electric forces arising from sand electrification can be strong enough to significantly affect the trajectories of saltating particles. The inclusion of electric forces in numerical models of saltation resolves large discrepancies between measurements and theory. The miniature electric field sensor (E-field sensor) developed at the University of Michigan (UM) has been used to test and refine these ideas.
Unlike traditional sensors, the UM E-field sensor is capable of making accurate measurements of electric fields even when subject to the impact of charged dust and sand particles. Moreover, it is capable of measuring E-fields at distances as small as a few centimeters from the surface, as demonstrated by laboratory and field tests. Indeed, the UM E-field sensor has been helping researchers gain insight into the interactions between aerosols and climate. This is extremely important because the effects of aerosols are one of the largest sources of uncertainty in current climate change models.