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Shallow cirrus convection – a source for ice supersaturation Cover

Shallow cirrus convection – a source for ice supersaturation

Open Access
|Dec 2014

Abstract

The origin and persistence of high ice supersaturation is still not well understood. In this study, the impact of local dynamics as source for ice supersaturation inside cirrus clouds is investigated. Nucleation and growth of ice crystals inside potentially unstable layers in the tropopause region might lead to shallow convection inside (layered) cirrus clouds due to latent heat release. The intrinsic updraught inside convective cells constitutes a dominant but transient source for ice supersaturation. A realistic case of shallow cirrus convection is investigated using radiosonde data, meteorological analyses and large-eddy simulations of cirrus clouds. The simulations corroborate the existence of ice supersaturation inside cirrus clouds as a transient phenomenon. Ice supersaturation is frequent, but determined by the life cycle of convective cells in shallow cirrus convection. Cirrus clouds driven by shallow cirrus convection are mostly not in thermodynamic equilibrium; they are usually in a subsaturated or supersaturated state.

Language: English
Page range: 19937 - 19937
Submitted on: Oct 23, 2012
Accepted on: Jul 21, 2014
Published on: Dec 1, 2014
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services

© 2014 Peter Spichtinger, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.