TY  - JOUR
A1  - Luo, Beiping
A1  - Peter, Thomas
A1  - Wernli, Heini
A1  - Fueglistaler, Stephan
A1  - Wirth, Martin
A1  - Kiemle, Christoph
A1  - Flentje, Harald
A1  - Yushkov, Vladimir A.
A1  - Khattatov, Vyacheslav
A1  - Rudakov, Vladimir V.
A1  - Thomas, Andreas
A1  - Borrmann, Stephan
A1  - Toci, Guido
A1  - Mazzinghi, Piero
A1  - Beuermann, Jürgen
A1  - Schiller, Cornelius
A1  - Cairo, Francesco
A1  - Di Donfrancesco, Guido
A1  - Adriani, Alberto
A1  - Volk, C.-Michael
A1  - Strom, Johan
A1  - Noone, Kevin
A1  - Mitev, Valentin
A1  - MacKenzie, Robert A.
A1  - Carslaw, Kenneth S.
A1  - Trautmann, Thomas
A1  - Santacesaria, Vincenzo
A1  - Stefanutti, Leopoldo
T1  - Ultrathin Tropical Tropopause Clouds (UTTCs): II. Stabilization mechanisms
T2  - Atmospheric chemistry and physics / Discussions, 3.2003, S. 1579-1597
N2  - Mechanisms by which subvisible cirrus clouds (SVCs) might contribute to dehydration close to the tropical tropopause are not well understood. Recently Ultrathin Tropical Tropopause Clouds (UTTCs) with optical depths around 10−4 have been detected in the western Indian ocean. These clouds cover thousands of square kilometers as 200–300 m thick distinct and homogeneous layer just below the tropical tropopause. In their condensed phase UTTCs contain only 1–5% of the total water, and essentially no nitric acid. A new cloud stabilization mechanism is required to explain this small fraction of the condensed water content in the clouds and their small vertical thickness. This work suggests a mechanism, which forces the particles into a thin layer, based on upwelling of the air of some mm/s to balance the ice particles, supersaturation with respect to ice above and subsaturation below the UTTC. In situ measurements suggest that these requirements are fulfilled. The basic physical properties of this mechanism are explored by means of a single particle model. Comprehensive 1-D cloud simulations demonstrate this stabilization mechanism to be robust against rapid temperature fluctuations of +/−0.5 K. However, rapid warming (ΔT>2 K) leads to evaporation of the UTTC, while rapid cooling (ΔT<−2 K) leads to destabilization of the particles with the potential for significant dehydration below the cloud.
Y1  - 2003
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/29274
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-292749
UR  - http://www.atmos-chem-phys.org/acpd/3/1579/
SN  - 1680-7367
SN  - 1680-7375
N1  - © Author(s) 2003. This work is licensed under a Creative Commons License.
VL  - 3
SP  - 1579
EP  - 1597
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -