Iberulite

[1] An iberulite is a co-association [2] [note 1] with axial geometry, consisting of well-defined mineral grains, together with non-crystalline compounds, structured around a coarse-grained core with a smectite rind, only one vortex and pinkish color (Figs.

[3] Flight over areas with anthropogenic or natural (volcanic, as those of North Atlantic archipelagos)[note 2] sulphur emissions probably adsorbs SO2 onto the iberulite surface.

Descent to the marine boundary layer (MBL) [4] [note 3] of the Iberian-Moroccan Atlantic coast leads to the incorporation of sea salt and microorganisms.

This location is geographically close to North Africa and it is therefore influenced by the emissions of Saharan aerosols, which are the greatest contributor of particulate matter to the atmospheric global dust budget [5] (Fig.

The aerosol contents, together with dissolved salts (detected in this sequence as whitish or shiny precipitates), would have gradually increased, finally producing a well-defined iberulite after desiccation (Fig.

It was observed during this passage that the central day presented the highest air temperatures and PM10 and PM2.5 (PM10>PM2.5) contents, whereas relative humidity decreased (RH).

[6] Iberulites are linked to the evolution of high-dust air masses (plumes) which, originating in Saharan dust storms, are transported over the Iberian Peninsula and often across the eastern North Atlantic Ocean.

These plumes occur in the warm season (May to September), as a result of anticyclone activity affecting the Iberian Peninsula, and only sporadically in spring.

[1][3][6] The movement of these water droplets to lower tropospheric levels implies either simultaneous or consecutive processes such as coalescence, formation of vortex and downdraught.

Fig. 1 Group of iberulites observed under SEM. The arrows show vortex position.
Fig. 2 Aspect of several iberulites under optical microscope.
Fig. 3 Emissions and dry/wet deposition of aerosols.
Fig. 4 Number of iberulite episodes (pl= plume, SA= Source Area, RA= Reception Area).
Fig. 5 Saharan dusty event occurring on August 15, 2005. Notice the change of direction of the plume towards the Cadiz Gulf.
Fig. 6 Traces of waterdroplets during a Saharan dust event.
Fig. 7 Time evolution of the particulate matter / Time evolution of the relative humidity (RH) and temperature.