On 30 October 1999, a moderate shallow south foehn event developed in the Brenner Pass target area in response to increased southwesterly flow ahead of an approaching sharp North Atlantic trough. Two dual aircraft missions were flown during this south foehn event: a morning mission by the P-3 and Electra, and an afternoon mission by the P-3 and ARAT. The P-3 performed low-level flight patterns where the primary goal was the use of in situ measurements to document the flow characteristics in the gap. The Electra and ARAT flew upper-level flight patterns where the primary goal was the use of remote sensing instrumentation to document the structure of the flow in the gap. Dropsondes deployed by the Electra and supplemental radiosondes deployed upstream and downstream of the pass will provide important information on the stratification of the flow. The Doppler lidar coverage, which depends on the availability of scatterers, was outstanding during this event (8 km in the vertical and 20 km in the horizontal) due to the presence of Saharan dust over the target area. Using a variety of scanning strategies, the lidar was able to map out the spatial variability of the flow within the valley and monitor the vertical structure of the flow at fine time resolution over a 10 hour time period. We plan to present a preliminary analysis of the flow within the gap based on the P-3 in situ measurements, as well as an overview of the flow structures documented by the Doppler lidar during this gap flow event.
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