Secondary Alpine potential vorticity banners: Sensitivity to model resolution

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 Alpine PV banners, which comprise an 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 examine the predicted structure of the secondary Alpine potential vorticity banners in two MAP SOP cases, and the sensitivity of that structure to the model horizontal resolution. The model used in this study is the Navy's Coupled Ocean/Atmosphere Modeling Prediction System (COAMPS), which has been shown previously using the MAP SOP data to produce realistic PV banner structures at the horizontal resolution of 3 km. The two secondary PV banners cases are IOP 8 and IOP 15, in which secondary PV banners were documented to the north of the Alps over Bavaria during an episode of deep south Foehn, and downwind of the Dinaric Alps over the Adriatic during a strong Bora.