Dust Radiation, Electrification and Alignment-DREAME

Recent observations of atmospheric Saharan dust by UH scientists provide strong evidence for the existence in mineral dust layers of particles that are predominantly vertically aligned. This alignment is thought to be due to atmospheric electricity associated with the dust layers. Computer modelling indicates that the alignment can significantly change the properties of the dust layers, including the amount of light they transmit, absorb and reflect. This has been termed a "Venetian blind effect" from the way the tilted particles influence the amount of transmitted light and heat. Change in this and other properties can have significant impact on measurements of dust clouds from satellites, and possibly also on dust movement through the atmosphere. The proposed project aims to answer urgent questions concerning the precise origin, magnitude, extent and impact of this phenomenon by the use of a variety of measurements from the ground, balloons and aircraft, carried out in the Middle East.

It was shown that airborne desert dust is electrically charged, to levels that can explain previous observations of the alignment of dust particles in the atmosphere. A byproduct of the project has been an aerosol radiosonde for launching on meteorological balloons, the first of its kind.