The GAP experiment, conducted in the Brenner cross-section region of the Alps during MAP, included the collection of high-resolution surface data from the Wipp and Inn valleys. These data consist of 30 second wind, temperature, pressure and humidity from 15 automatic weather stations and 2 second turbulence data from 3 towers. Cross-correlation analysis of the 30 second data has been used to detect and investigate propagation of disturbances along the Wipp valley during Foehn conditions. The evolution of the spectral characteristics of the flow along the valley has also been investigated and related to Foehn flow.

Separate analysis of surface pressure data, data from an instrumented car and application of a shallow water model points to the existence of regions of super-critical and sub-critical flow, and jump-like structures. The propagation characteristics add further support to this interpretation. A marked absence of downstream propagation of disturbances through regions of suspected jumps is observed. In the lower (and sub-critical) parts of the valley, spectra show enhancement at high frequencies, possibly connected with turbulence generation at the jumps.