Six PV banner missions were realized during the Special Observation Period (SOP) of the Mesoscale Alpine Programme (MAP) in Sept-Nov 1999. Four of these missions were carried out to document secondary PV banners along different sections of the Alps. As opposed to the primary PV banners which emanate from the end points of a mountain range, secondary PV banners comprise the interior of the mountain-range wake, and mark wind shearlines that originate from massifs and isolated peaks along the complex mountain-range ridgeline.

In this study we focus on two secondary PV banner cases from MAP SOP. One of the cases took place in IOP 8, on October 21, during an episode of deep south Foehn, with the examined portion of the wake located to the north of the Alps over Bavaria. The other case took place in IOP 15, on November 7, during a strong Bora, with the examined wake located downwind of the Dinaric Alps over the Adriatic. Using the available in situ and remotely sensed aircraft data, drop sonde data, satellite imagery, and the high-resolution numerical simulation predictions from two mesoscale models, COAMPS and MC2, we examine similarities and differences of the wake and secondary PV banner structure, and the origin of potential vorticity anomalies in these two cases of strong cross-mountain downslope flow.