@Yves70
This map is important for people living in the vicinity of the Sahara, such as in the Maghreb, Spain, southern Italy, Greece, etc..., for health problems and for haze / reduced visibility that the high content of mineral particles may bring. It is also in a way the tracer of this hot, dry air that we see moving at certain times of the year towards America, reducing the risk of cyclonic development in the Atlantic. However, I do not know what additional information @Microbill want to obtain from the position and establishment of the Sahara Air Layer.