Gravity waves generated by convection during TWP‐ICE: 2. High‐frequency gravity waves

Abstract

AbstractHigh‐frequency gravity waves are analyzed using radiosonde soundings taken during the Tropical Warm Pool‐International Cloud Experiment (TWP‐ICE). The intrinsic periods of these waves are estimated to be between 10 and 50 min. The high‐frequency wave activity in the stratosphere, defined by mass‐weighted variance of the vertical motion of the sonde, has a maximum following the afternoon local convection indicating that these waves are generated by local convection. The wave activity is the strongest in the lower stratosphere below 22 km and, during the suppressed monsoon period, is modulated with a 3–4 day period. The concentration of the wave activity in the lower stratosphere is consistent with the properties of the environment in which these waves propagate, whereas its 3–4 day modulation is explained by the variation of the convection activity in the TWP‐ICE domain. For shallow convection, the wave activity has a weak tendency to increase as the rainfall intensity increases. The wave activity associated with deep convection, which typically occurs at high rainfall intensities, is larger and has more spread than that associated with shallow convection.