Gravity waves generated by convection during TWP-ICE
Poster PDF
Authors
Michael Reeder — Monash University
Mai Nguyen — Monash University
Todd Lane — University of Melbourne
Category
Dynamics/Vertical Motion
Description
Gravity waves are identified in the radiosonde observations from the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) campaign and their properties deduced. For the high-frequency waves, the intrinsic period is between 20–40 minutes. The wave activity, quantified by mass-weighted variance of the vertical motion perturbations, exhibits three main features. First, the wave activity in the stratosphere has a maximum following the afternoon local convection, indicating that these waves are generated by local convection. Second, at high rain rates, there is no clear relationship between the wave activity and the rain rate, suggesting that processes other than diabatic heating by convection play roles in generating these gravity waves. Third, the wave activity was strongest in the lower part of the stratosphere below 22 km and, during the suppressed monsoon period, varies on a time scale of 3–4 days. The concentration of the wave activity in the lower stratosphere is found to be consistent with the properties of the environment in which these waves propagated (using the Scorer parameter), whereas its 3–4-day modulation is due to the variation of the convection activity in the TWP-ICE domain.
