Mayer, JC; Staudt, K; Gilge, S; Meixner, FX; Foken, T: The impact of free convection on late morning ozone decreases on an Alpine foreland mountain summit, Atmospheric Chemistry and Physics, 8, 5941-5956 (2008) [Link]
Key words: free convection,SALSA,Hohenpeißenberg, Alpine pumping,trace gases
Exceptional patterns in the diurnal course of ozone mixing ratio at a mountain top site (998 m a.s.l.) were observed during a field experiment (September 2005). They manifested themselves as strong and sudden decreases of ozone mixing ratio with a subsequent return to previous levels. The evaluation of corresponding long-term time series (2000–2005) revealed that such events occur mainly during summer, and affect the mountain top site on about 18% of the summer days. Combining (a) surface layer measurements at mountain summit and at the foot of the mountain, (b) in-situ (tethered balloon) and remote sensing (SODAR-RASS) measurements within the atmospheric boundary layer, the origin of these events of sudden ozone decrease could be attributed to free convection. The free convection was triggered by a rather frequently occurring wind speed minimum around the location of the mountain.

last modified 2008-10-16