Profiling mineral dust with UAV-based in-situ instrumentation (Cyprus Fall campaign 2021)

Unmanned Aerial Vehicle (UAV)-sensor systems allow for cost-effective vertically-resolved in-situ atmospheric observations within the lower troposphere. Taking advantage of the private runway and dedicated airspace of the Unmanned Systems Research Laboratory (USRL; https://usrl.cyi.ac.cy/) of the Cyprus Institute in Orounda (Nicosia, Cyprus), an intensive campaign focusing on mineral dust observations was conducted between 18 October and 18 November 2021. This, involved UAV flights (36 in total) and ground-based active and passive remote-sensing observations during two distinct dust outbreaks over Cyprus.

The first dust event occurred between 25 October and 1 November 2021, and HYSPLIT back-trajectories revealed that the observed air masses were mainly originated from NE Sahara (Libya, Egypt). The second dust event was observed from 13 to 18 November 2021. HYSPLIT back-trajectories revealed that the observed air masses at the beginning of the second event were originated from the Middle East (Saudi Arabia, Syria), but the air mass origin switched to NW Saharan dust midways through the event. The Aerosol Optical Depth at 500-nm as measured by our sun-photometers was found to be above 0.2 all the time, and in some days reached up to 0.5. The observed aerosol layers were found to be extending from ground up to 5 km Above Sea Level (ASL).

This study presents results of the vertical aerosol structure/height-resolved information of each dust event from its arrival to its departure as observed by instruments on-board the UAVs including: a pair of Universal Cloud and Aerosol Sounding System (UCASS) Optical Particle Counters (OPCs), Printed Optical Particle Spectrometer (POPS) OPC, Compact Optical Backscatter AerosoL Detector (COBALD) and filter samplers.