Séminaire
Recent studies using satellite observations show that numerous dust sources are located in the foothills of the Saharan mountains. Generally, dust emission is closely related to sediment supply and wind speeds. Thus, dust emission can be inhibited by either lack of high wind speeds or by surface characteristics. Studies on the activity of potential dust sources show a marked interannual variability, the reasons of which are not fully understood.
Significant rainfall and flash flood events are assumed to lead to changes in pluvial sediment supplies in mountain drainage systems. These sediments are suitable for dust uplift and assumed to have a main contribution to the dust emission fluxes over these areas. Here, results of a study investigating the role of pluvial sediment supply in drainage systems within the foothills of Saharan mountains for dust emission and its interannual variability will be presented. For a selected area over West Sahara, ENVISAT SAR measurements are analysed to identify changes in surface sediments through loss of coherence between two consecutive images for 2003-2010. Furthermore, first results from the RAIN4DUST/Fennec aircraft campaign over north Mauritania investigating the dust source activity over this area will be shown.
TRMM daily rainfall rates are used to identify days with significant rainfall in order to check on plausibility and if positive to give exact timing of flooding. In addition, to analyse dustiness over this area, remote sensing products indicating atmospheric dust content are analysed with regards to interannual variability of dustiness over this area.