Intraseasonal variability and atmospheric controls on daily dust occurrence frequency over the central and western Sahara during the boreal summer

We classify satellite‐derived maps of daily dust occurrence frequency over the central and western Sahara (CWS) during the boreal summer in order to identify typical patterns using the neural network based system of self‐organized maps. Resulting dust states vary in terms of the frequency of dust occurrence and its location. The most commonly occurring dust states are those of relatively low dust detection frequency. On days with relatively high dust occurrence, dust tends to favor either a location close to the Algeria‐Mali‐Niger border triple point (TP) or further to the northwest across the western half of the Mali‐Algeria border (MAB). States in which dust is detected at both locations simultaneously are rare. There is a distinct intraseasonal progression in preferred dust location from the TP in the early season to the MAB later in the season. The evolution of dust states reveals a one‐way transition from dust at the TP to dust at the MAB and then to reduced daily dust occurrence frequency. There is a distinct degree of interannual variability in the occurrence frequency of the different states, dominated by the extremes of high and low dust detection frequency. Analysis of climatological composites demonstrates that monsoon surges into the Saharan heat low are associated with days of high dust detection frequency, while a strong Harmattan into the CWS is linked to days with less frequent dust presence. The CWS atmospheric dust budget for June–August is thus strongly linked to the dynamics of the West African monsoon.