Stratospheric influence on upper tropospheric tropical cirrus

Radiosonde data from the Department of Energy (DOE) Atmospheric Radiation M easurement (ARM) program Nauru99 experiment revealed waves with downward ph ase propagation from the lower stratosphere into the upper troposphere. The occurrence of cirrus clouds and the tropical tropopause structure were clo sely related to these waves. This study reveals a close relationship betwee n upper tropospheric cirrus and large-scale dynamics, suggesting that tropi cal cirrus cannot be studied in isolation from planetary scale forcing.