  Atmospheric electric field (AEF) measurements were carried out in three
different sites forming a triangular array in Southern Portugal. The campaign
was performed during the summer characterized by Saharan dust outbreaks; the
16th-17th July 2014 desert dust event is considered here. Evidence of
long-range dust electrification is attributed to the air-Earth electrical
current creating a positive space-charge inside of the dust layer. An increase
of ~23 V/m is observed in AEF on the day of the dust event corresponding to
space-charges of ~20-2 pCm-3 (charge layer thicknesses ~10-100 m). A reduction
of AEF is observed after the dust event.
