EGU23-14150, updated on 16 May 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Cirrus clouds in the tropical tropopause layer observed at Koror, Palau (7.34°N, 134.47°E)

Xiaoyu Sun1, Mathias Palm1, Christoph Ritter2, and Justus Notholt1
Xiaoyu Sun et al.
  • 1Institute of Environmental Physics, University of Bremen, Bremen, Germany
  • 2Helmholtz Centre for Polar and Marine Research, Alfred Wegener Institute, Potsdam, Germany

A Compact Cloud and Aerosol LIDAR (ComCAL) is operated in Koror, Palau (7.34°N, 134.47°E) since 2018. Palau is located in the Pacific warm pool, which plays an important role in global stratosphere-troposphere exchange in the upper troposphere and the lower stratosphere (UTLS). ComCAL is operated during nighttime, carried out observations of atmospheric profiles of aerosols and clouds, and the lidar profile extends from 8 km to 30 km. Cirrus clouds were detected with very high occurrence in the upper troposphere (above 12 km). The subvisible clouds (with an optical thickness of less than 0.3) often occur in the higher region of the tropical tropopause layer (TTL) above about 16 km which is close to the cold point. The transport of air in this layer with thin cirrus and subvisible clouds was investigated by the TRACZILLA Lagrangian model, a variation of FLEXPART. The back-trajectory analysis gives insight into the origins of cirrus clouds in the TTL whether it is related to the convection or the in situ uplifting of the air masses.

How to cite: Sun, X., Palm, M., Ritter, C., and Notholt, J.: Cirrus clouds in the tropical tropopause layer observed at Koror, Palau (7.34°N, 134.47°E) , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14150,, 2023.