ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-8-2849-2008 Correlation between equatorial Kelvin waves and the occurrence of extremely thin ice clouds at the tropical tropopause Immler F. 1 Krüger K. 2 Fujiwara M. 3 Verver G. 4 Rex M. 5 Schrems O. 6 German Meteorological Service, Richard-Aßmann-Observatory, Lindenberg, Germany IFM-GEOMAR, Kiel, Germany Hokkaido University, Faculty of Environmental Earth Science, Japan Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany 13 02 2008 8 1 2849 2862 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/8/2849/2008/acpd-8-2849-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/8/2849/2008/acpd-8-2849-2008.pdf

A number of field-campaigns in the tropics have been conducted in the recent years with two different LIDAR systems at Paramaribo in Suriname (5.8° N, 55.2° W). 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 show that temperature anomalies caused by equatorial Kelvin waves propagate downward, well below the cold point tropopause (CPT). We find 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. This finding suggests an influence of Kelvin wave activity on the dehydration in the TTL and thus on the global stratospheric water vapour concentration.

 References Boehm, M. and Verlinde, J.: Stratospheric influence on upper tropospheric tropical cirrus, Geophys. Res. Lett., 27, 3209–3212, \doi2000GL011678, 2000. Bonazzola, M. and Haynes, P H.: A trajectory-based study of the tropical tropopause region, J. Geophys. Res., 109, D20112, \doi10.1029/2003JD004356, 2004. Comstock, J M., Ackerman, T P., and Mace, G G.: Ground-based lidar and radar remote sensing of tropical cirrus clouds at Nauru Island: Cloud statistics and radiative impacts, J. Geophys. Res., 107, 4714, \doi10.1029/2002JD002203, 2002. Fueglistaler, S., Bonazzola, M., Haynes, P H., and Peter, T.: Stratospheric water vapor predicted from the Lagrangian temperature history of air entering the stratosphere in the tropics, J. Geophys. Res., 110, D08107, \doi10.1029/2004JD005516., 2005. Fujiwara, M., Hasebe, F., Shiotani, M., Nishi, N., Voemel, H., and Oltmans, S J.: Water vapor control at the tropopause by equatorial Kelvin waves observed over the Galapagos, Geophys. Res. Lett., 28, 3143–3146, 2001. Fujiwara, M., Xie, S.-P., Shiotani, M., Hashizume, H., Hasebe, F., Vömel, H., Oltmans, S J., and Watanabe, T.: Upper-tropospheric inversion and easterly jet in the tropics, J. Geophys. Res., 108, 4796, \doi10.1029/2003JD003928, 2003. Gettelman, A., Forster, P M. de F., Fujiwara, M., Fu, Q., Vömel, H., Gohar, L K., Johanson, C., and Ammerman, M.: Radiation balance of the tropical tropopause layer, J. Geophys. Res., 109, D07103, \doi10.1029/2003JD004190, 2004. Holton, J., Alexander, M., and Boehm, M.: Evidence for short vertical wavelength Kelvin waves in the Department of Energy-Atmospheric Radiation Measurement Nauru99 radiosonde data, J. Geophys. Res., 106, 20 125–20 130, 2001. Immler, F. and Schrems, O.: Determination of tropical cirrus properties by simultaneous LIDAR and radiosonde measurements, Geophys. Res. Lett., 29, \doi10.1029/2002GL015076, 2002. Immler, F., Beninga, I., Ruhe, W., Stein, B., Mielke, B., Rutz, S., Terli, O., and Schrems, O.: A new LIDAR system for the detection of cloud and aerosol backscatter, depolarization, extinction, and fluorescence, reviewed and revised papers presented at the 23rd International Laser Radar Conference, 24–28 July 2006, 35–38, 2006. Immler, F., Krüger, K., Tegtmeier, S., Fujiwara, M., Fortuin, P., Verver, G., and Schrems, O.: Cirrus clouds, humidity, and dehydration in the tropical tropopause layer observed at Paramaribo, Suriname (5.8° N, 55.2° W), J. Geophys. Res., 112, D03209, \doi10.1029/2006JD007440, 2007. Jensen, E. and Pfister, L.: Transport and freeze-drying in the tropical tropopause layer, J. Geophys. Res., 109, D02207, \doi10.1029/2003JD004022, 2004. Krüger, K., Tegtmeier, S., Wohltmann, I., and Rex, M.: Long-term climatology of transport processes in the Tropical Tropopause Layer (TTL) during NH winter, Atmos. Chem. Phys. Discuss., 7, 13 989–14 010, 2007. Luo, B. P., Peter, T., Fueglistaler, S., Wernli, H., Wirth, M., Kiemle, C., Flentje, H., Yushkov, V. A., Khattatov, V., Rudakov, V., Thomas, A., Borrmann, S., Toci, G., Mazzinghi, P., Beuermann, J., Schiller, C., Cairo, F., Di Donfrancesco, G., Adriani, A., Volk, C. M., Strom, J., Noone, K., Mitev, V., MacKenzie, R. A., Carslaw, K. S., Trautmann, T., Santacesaria, V., and Stefanutti, L.: Dehydration potential of ultrathin clouds at the tropical tropopause, Geophys. Res. Lett., 30, 1557, doi:10.1029/2002GL016737, 2003. Massie, S., Gettelman, A., Randel, W., and Baumgardner, D.: Distribution of tropical cirrus in relation to convection, J. Geophys. Res., 107, 4591, \doi10.1029/2001JD001293, 2002. Nielsen, J K., Larsen, N., Cairo, F., Donfrancesco, G D., Rosen, J M., Durry, G., Held, G., and Pommereau, J P.: Solid particles in the tropical lowest stratosphere, Atmos. Chem. Phys., 7, 685–695, 2007. Peter, T., Luo, B. P., Wernli, H., Wirth, M., Kiemle, C., Flentje, H., Yushkov, V. A., Khattatov, V., Rudakov, V., Thomas, A., Borrmann, S., Toci, G., Mazzinghi, P., Beuermann, J., Schiller, C., Cairo, F., Don-francesco, G. D., Adriani, A., Volk, C. M., Ström, J., Noone, K., Mitev, V., MacKenzie, R. A., Carslaw, K. S., Trautmann, T., Santacesaria, V., and Stefanutti, L.: Ultrathin Tropical Tropopause Clouds (UTTCs): I. Cloud morphology and occurrence, Atmos. Chem. Phys., 3, 1083–1091, 2003. Winker, D. and Trepte, C.: Laminar cirrus observed near the tropical tropopause by LITE, Geophys. Res. Lett., 25, 3351–3354, 1998.