In situ detection of electrified aerosols in the upper troposphere and stratosphere

Jean-Baptiste Renard (1) , S. N. Tripathi (2) , M. Michael (2) , A. Rawal (2) , Gwenaël Berthet (1) , Martin Füllekrug (3) , R.G. Harrison (4) , C Robert (1) , Michel Tagger (1) , Bertrand Gaubicher (1)

1 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
2 CESE - Centre for Environmental Science and Engineering [Kanpur]
3 Department of Electronics and Electrical Engineering [Bath]
4 Department of Meteorology [Reading]

Electrified aerosols have been observed in the lower troposphere and in the mesosphere, but have never been detected in the stratosphere and upper troposphere. We present measurements of aerosols obtained during a balloon flight to an altitude of 24 km. The measurements were performed with an improved version of the Stratospheric and Tropospheric Aerosol Counter (STAC) aerosol counter dedicated to the search for charged aerosols. It is found that most of the aerosols are charged in the upper troposphere for altitudes below 10 km and in the stratosphere for altitudes above 20 km. Conversely, the aerosols seem to be uncharged between 10 km and 20 km. Model calculations are used to quantify the electrification of the aerosols with a stratospheric aerosol-ion model. The percentages of charged aerosols obtained with model calculations are in excellent agreement with the observations below 10 km and above 20 km. However, the model cannot reproduce the absence of electrification found in the lower stratosphere, as the processes leading to neutralisation in this altitude range are unknown. The presence of sporadic transient layers of electrified aerosol in the upper troposphere and in the stratosphere could have significant implications for sprite formation.

Domains: Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]; Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]

Jean-Baptiste Renard, S. N. Tripathi, M. Michael, A. Rawal, Gwenaël Berthet, et al.. In situ detection of electrified aerosols in the upper troposphere and stratosphere. Atmospheric Chemistry and Physics, 2013, 13, pp.11187-11194. ⟨10.5194/acp-13-11187-2013⟩. ⟨insu-00906586⟩