HR: 0800h
AN: A21E-0800    [Abstracts]
TI: Cirrus Clouds, Equatorial Kelvin Waves and Dehydration in the Tropical Tropopause Layer
AU: * Schrems, O
EM: Otto.Schrems@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, D-27570, Germany
AU: Immler, F
EM: Franz.Immler@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, D-27570, Germany
AU: Krueger, K
EM: kkrueger@ifm-geomar.de
AF: IFM-GEOMAR, Duesternbrooker Weg 20, D-24105, Kiel, Germany
AU: Rex, M
EM: Markus.Rex@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Telegrafenberg A43, Potsdam, D-14473, Germany
AU: Fujiwara, M
EM: fuji@ees.hokudai.ac.jp
AF: Hokkaido University, Faculty for Environmental Earth System, Sapporo, 060-0810, Japan
AB: A number of field-campaigns in the tropics have been conducted in the past years with the mobile LIDAR systems MARL and ComCAL of the Alfred Wegener Institute aboard the research vessel Polarstern in the tropical Atlantic and at Paramaribo in Suriname. The lidars detect particles in the atmosphere with high vertical and temporal resolution and are capable of detecting extremely thin cloud layers which frequently occur in the tropical tropopause layer (TTL). We investigated the occurrence of clouds in the TTL with a newly developed trajectory model and found that ice particles form in slow ascent and efficiently dehydrate the air. The Lagrangian temperature history thus defines the water vapour transported to the stratosphere in the tropics. Radiosonde as well as ECMWF operational analysis data show a strong influence of eastward moving equatorial Kelvin waves on the temperature at the tropical cold point tropopause (CPT). We find a clear correlation between the temperature anomalies introduced by these waves and the occurrence of thin cirrus. This finding suggests an influence of Kelvin wave activity on the dehydration characteristics of the TTL
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting