Atmos. Chem. Phys. Discuss., 4, 8327-8355, 2004
www.atmos-chem-phys-discuss.net/4/8327/2004/
doi:10.5194/acpd-4-8327-2004
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Analysis of water vapor LIDAR measurements during the MAP campaign: evidence of sub-structures of stratospheric intrusions
P. D’Aulerio1,2, F. Fierli1, F. Congeduti1, and G. Redaelli2
1Institute of Atmospheric Sciences and Climate, CNR, Roma, Italy
2Department of Physics, University of L’Aquila, L’Aquila, Italy

Abstract. This paper presents case studies of dehydration in the free troposphere measured by a ground based Raman LIDAR in the Northern-Italy, during the Mesoscale Alpine Programme (MAP). Two observations characterized by the presence of anomalously dry layers, below 6 km height, were analyzed using Lagrangian techniques. These events are related to upper-tropospheric, high Potential Vorticity streamers crossing the Alpine region and are interpreted as small-scale features of stratospheric intrusions associated to the PV ridge during its breakout phase. One of the measurements also shows the presence of two distinct dehydrated structures associated to the same event. The water vapor concentration also suggests dilution processes of dry stratospheric air in the troposphere. Lagrangian simulations allowed to successfully reproduce the observed water vapor distribution and the air parcel histories confirmed the stratospheric origin of the dry layers.

Citation: D’Aulerio, P., Fierli, F., Congeduti, F., and Redaelli, G.: Analysis of water vapor LIDAR measurements during the MAP campaign: evidence of sub-structures of stratospheric intrusions, Atmos. Chem. Phys. Discuss., 4, 8327-8355, doi:10.5194/acpd-4-8327-2004, 2004.
 
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