Turbulence Analysis in Long-Range-Transported Saharan Dust Layers With Airborne Lidar

Kurzfassung

Abstract In this study, turbulent properties of long-range-transported Saharan dust layers are investigated for the first time using airborne backscatter and water vapor lidar measurements. This is achieved via the utilization of spectral signal decomposition to the collected lidar data. Additionally, measurements by dropsondes are analyzed in detail. The presented measurements were conducted during the Next-Generation Aircraft Remote Sensing for Validation Studies II in boreal summer 2016 upstream Barbados. An analysis of two case studies shows that the derived mesoscale turbulence cascades inside the transported dust layers follow the predicted slopes for turbulence of -5/3. The turbulent nature of the Saharan air layers (SALs) is additionally indicated by small Richardson numbers, which are derived from data collected by launched dropsondes. These presented results also fortify the hypothesis that turbulence inside dust layers helps to keep large mineral dust particles aloft for a longer time, so that they can still be found after long-range transport.