Click on the image to see the animation showing the dust plume over Europe
Over the weekend a strong outbreak of Saharan dust affected large regions of Europe and lead to number of photos as seen in Figure 1 with red-coloured skies and dramatically decreased visibility. Such conditions were observed by many ALC’s (Automatic lidars and ceilometers) in the E-PROFILE network, as illustrated in Figure 2. The origin of the air is clearly Saharian as indicated by the back-trajectories in Figure 3.
Dense 24/7 networks such as E-PROFILE are an ideal tool to monitor the horizontal, vertical and temporal distribution of aerosols and prove extremely useful to assess the situation in such events. This is illustrated by Figures 4-6 which indicate how the dust plume moved over Europe. It was located over Spain on 05 February before gradually moving towards the North and East during 06 and 07 February. This is a showcase for Saharan dust mixed into the boundary layer, but such a monitoring is possible for any aerosol type at any tropospheric altitude.
Fig.1 Strong limitation in visibility and atmosphere in reddish colours in the Swiss prealps. Picture taken by Alexander Haefele in the afternoon of 06 February 2021.
Fig.2 Attenuated back scatter observed on 06 Feb by the E-PROFILE ALC in Bern, Switzerland, in proximity to the location of the picture in Figure 1. A massive intrusion of Saharan dust reaching the boundary layer in the late morning can be observed.
Fig.3 Back-trajectories arriving in Bern, Switzerland on 06 Feb 12:00 for different altitudes. They clearly indicate the Saharan origin of the airmass. Data from HYSPLIT accessible at www.ready.noaa.gov.
Fig.4 Overview of attenuated backscatter profiles observed on 05 Feb at several central-European stations. The area delimited by the orange line denotes the area where high dust concentrations were observed. Interactive view at: https://e-profile.eu/#/?currentView=CMProfile&measurementDate=2021-02-05&QLSize=70
Fig. 5: Overview of attenuated backscatter profiles observed on 06 Feb at several central-European stations The area delimited by the orange and blue lines denote the area where high dust concentrations were observed during the morning and the afternoon, respectively. Interactive view at: https://e-profile.eu/#/?currentView=CMProfile&measurementDate=2021-02-06&QLSize=70
Fig. 6: Overview of attenuated backscatter profiles observed on 07 Feb at several central-European stations. The area delimited by the orange line denotes the area where high dust concentrations were observed. Interactive view at: https://e-profile.eu/#/?currentView=CMProfile&measurementDate=2021-02-07&QLSize=70
More images of the phenomenon in the Swiss Alps near Grand Saint-Bernard
