Mud transport from the Sahara to the Mediterranean

By Anu-Maija Sundström (FMI/AC SAF), Francesca Barnaba & the Alicenet crew, Federico Fierli, Julia Wageman

The intensive mud plume is clearly seen in a number of satellite tv for pc observations. This additionally brought about a drop in air high quality at a number of areas within the Mediterranean area. Floor-based lidar observations from Italy present a number of layers of mud from south to north of the peninsula, principally impacting atmospheric layers between 2 and 5 km, with intrusions into the boundary layer ranging from 20 June, thus impacting native air high quality.

Sturdy winds in North West Sahara lifted a considerable amount of mud that has been transported throughout the western a part of the Mediterranean. An animation of the MSG mud air mass product reveals how the mud plume (colored pink) over North Algeria begins to unfold in direction of the Mediterranean on 19 June 2023.

Absorbing Aerosol Index (AAI) from GOME-2 devices onboard Metop-B and -C satellites reveals the unfold of the plume earlier than midday on 20 June (Determine 1).

Determine 1: MSG Mud air mass animation from 19 June 09:45UTC-20 June 18:45UTC. In these observations mud is coloured with shades of pink. Firstly of the animation a mud plume over North Algeria is clearly seen. Within the following hours it begins to unfold in direction of the Mediterranean.

Within the early morning (04:45 UTC) scan of the MSG satellite tv for pc on 21 June, the mud plume is clearly seen over Italy (Determine 2). Presently of the day when the solar is low within the sky, the options of mud plumes are enhanced in RGB pictures from a geostationary satellite tv for pc.

Determine 2: GOME-2 Absorbing Aerosol Index (Metop-B & Metop-C) observations on 20 June earlier than midday. For mud, or different sorts of absorbing aerosol plumes (volcanic ash, smoke) AAI index values are optimistic, usually bigger than 1. The GOME- AAI observations are supplied by the AC SAF.

The mud transport has additionally affected air high quality within the Mediterranean (Determine 3). On 21 June, a number of ground-based stations within the Balearic Islands and the south coast of France measured average to poor air high quality index (Determine 4) attributable to elevated PM10 concentrations (particles smaller than 10 micrometers in diameter) brought on by the mud. The extent of the plume on 21 June earlier than midday is proven by GOME-2 AAI observations (Determine 5).

Determine 3: MSG RGB picture from 21 June 04:45 UTC. The brownish mud plume over Italy is clearly seen.

Determine 4: The European Air High quality Index on 21 June at 10:00 UTC confirmed average to very poor air high quality at a number of stations within the Balearic Islands and south coast of France. The principle pollutant in every of those stations was elevated PM10 focus brought on by the Saharan mud. See the European Air High quality Index web site.

Determine 5: GOME-2 AAI observations from Metop-B and -C on 21 June 2023 earlier than midday. The GOME- AAI observations are supplied by AC SAF.

The synergy between house and ground-based observations is crucial to characterize correctly the mud occasion evolution, relating the plume peak with the geographical distribution.

Observations from the bottom could make use of energetic distant sensing (similar to lidars / ceilometers) to establish the temporal evolution of the aerosol profile over a sure web site.

Determine 6: Aerosol vertical profiles (0-5 km altitude, y axis) measured between June 19 and 21 (x axis) in chosen websites of the Italian Alicenet community. The graphs present (high panels) the aerosol backscatter (m-1 sr-1) and, the place out there (backside panels), the linear depolarization (%). Desert mud plumes have been highlighted with oval shapes to facilitate their identification within the graphs. A preliminary cloud screening was utilized to the information (white stripes).

Alicenet is a rising consortium established and coordinated by CNR-ISAC and involving completely different companion establishments in Italy. It additionally contributes to the European E-PROFILE program run by EUMETNET. The community extends from North to Southern Italy, thus masking a variety of atmospheric and environmental situations inside the Mediterranean space.

Desert mud plumes throughout Italy (Determine 6) have been detected by means of energetic distant sensing devices operationally (24/7) monitoring aerosol vertical profiles and clouds inside the Italian Alicenet community. Determine 6 reveals examples of Alicenet aerosol vertical profiles recorded between 19 and 21 June. It clearly reveals the excessive (yellow coloration) aerosol load (expressed by way of backscatter) related to the arrival of the desert mud plume between 2 and 5 km altitude, with the upper values noticed within the Italian southernmost websites in Sicily. The mud plume is proven to firstly affect south-west Italy (19 June) and to increase to northern websites on 20 June, with a fancy layering. ALC profiles additionally present the plume to descend to the lowermost atmospheric ranges on 21 June, thus impacting native PM air high quality. In these Alicenet websites having the aerosol depolarization info, the rise in depolarization (backside panels, crimson coloration) related to the non-spherical nature of mud particles is clearly detectable.

Further content material

CAMS mud forecast (Mark Parrington/twitter)

Barcelona Mud (twitter)

Worldview earth knowledge (twitter)

CNR-ISAC (Italy/twitter)

CNR (Italy/twitter)