Correlation between equatorial Kelvin waves and the occurrence of extremely thin ice clouds at the tropical tropopause F. Immler1,*, K. Krüger2, M. Fujiwara3, G. Verver4, M. Rex5, and O. Schrems1 1Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany 2IFM-GEOMAR, Kiel, Germany 3Hokkaido University, Faculty of Environmental Earth Science, Japan 4Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands 5Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany *now at: Richard Aßmann Observatory, Lindenberg, German Meteorological Service (DWD), Germany
Abstract. A number of field-campaigns in the tropics have been conducted in recent
years with two different LIDAR systems at Paramaribo (5.8° N,
55.2° W), 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). Radiosonde as well as operational ECMWF analysis showed that
equatorial Kelvin waves propagated in the TTL and greatly modulated its
temperature structure. We found a clear correlation between the temperature
anomalies introduced by these waves and the occurrence of thin cirrus in the
TTL. In particular we found that extremely thin ice clouds form regularly
where cold anomalies shift the tropopause to high altitudes. These findings
suggest an influence of Kelvin wave activity on the dehydration in the TTL
and thus on the global stratospheric water vapour concentration.
Citation: Immler, F., Krüger, K., Fujiwara, M., Verver, G., Rex, M., and Schrems, O.: Correlation between equatorial Kelvin waves and the occurrence of extremely thin ice clouds at the tropical tropopause, Atmos. Chem. Phys., 8, 4019-4026, doi:10.5194/acp-8-4019-2008, 2008.