Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 6 5 2006 10.5194/acpd-6-9003-2006 http://www.atmos-chem-phys-discuss.net/6/9003/2006/ http://www.atmos-chem-phys-discuss.net/6/9003/2006/acpd-6-9003-2006.html http://www.atmos-chem-phys-discuss.net/6/9003/2006/acpd-6-9003-2006.pdf 9003 9032 2006-09-25 Solid particles in the tropical lowest stratosphere J. K. Nielsen N. Larsen F. Cairo G. Di Donfrancesco J. M. Rosen G. Durry G. Held J. P. Pommereau Danish Meteorological Institute, Lyngbyvej 100, 2100 Kbh. Ø, Denmark Institute for Atmospheric Science and Climate, CNR, Via del Fosso del Cavaliere 100, 00133 Rome, Italy Italian National Agency for New Technologies, Energy and Environment, ENEA C. R. Cassaccia, Via Anguillarese 301, 00060 Rome, Italy University of Wyoming, Department of Physics and Astronomy, Laramie, Wyoming 82071 43;Groupe de Spectrometrie Moleculaire et Atmospherique, CNRS, Universite de Reims , 51687 Reims, France Instituto de Pesquisas Meteorol&#2gicas, Universidade Estadual Paulista, CX Postal, 281 17015-970 BAURU, S.P., Brasil CNRS, Institut Pierre Simon Laplace, Service d’Aeronomie, B.P. 3, 91371 Verrieres le Buisson Cedex, France We report in situ and remote observations proving occasional occurrence of solid particles in the tropical lowest stratosphere, far away from deep convective events. The particles were found during field campaigns in Southeast Brazil (49.03 W 22.36 S). They occur in the altitude range from 17.5 to 20.8 km, at temperatures up to at least 10 K above the expected frost point temperature. While stability of ice particles at these altitudes is unexpected from a theoretical point of view, it is argued that these observations are indications of tropospheric air masses penetrating into the stratosphere during convective overshoots. It is concluded that the intrusion of tropospheric air must have carried a large amount of water with it, which effectively hydrated the lowest stratosphere, and consequently suppressed sublimation. This conclusion is further supported by a separate water vapor mixing ratio profile obtained at the same observation site.