Gravity waves over the eastern Alps: A synopsis of the 25 October 1999 event (IOP 10) combining in situ and remote‐sensing measurements with a high‐resolution simulation

Abstract

In situ and lidar data acquired during six repetitive flight legs across Grossglockner (3797 m, highest summit of the eastern Alps) reveal a coherent structure of the mountain‐wave field generated by a south‐westerly cross‐Alpine flow on 25 October 1999 during Intensive Observing Period (IOP) 10 of the Mesoscale Alpine Programme (MAP). The downward‐looking laser system sampling at 100 Hz provides distinct wave‐induced signatures in the layered clouds below the cruising altitude of about 11 km. Data obtained from three sondes dropped from the aircraft hint at mid‐tropospheric wave breaking in the lee of the main Alpine crest. The measurements are juxtaposed with results from a nested, non‐hydrostatic simulation (2 km horizontal resolution for the finest grid). Wave‐cloud signatures in satellite images (from Meteosat and the National Oceanic and Atmospheric Administration satellites) are used for comparisons with the simulation in a region away from the aircraft track. Sensitivity experiments reveal the regular wave response to be induced by the background profile and re‐enforced by the suitably spaced terrain. Copyright © 2003 Royal Meteorological Society.

Gravity Wave Breaking over the Central Alps: Role of Complex Terrain

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