Stokes Parameter Analysis of A Packet of Turbulence-generating Gravity Waves

Abstract

Stokes parameter analysis for small-scale gravity waves was carried out from a set of aircraft observational data. The goal is to understand the polarization properties associated with gravity waves when turbulence is generated so that enough physical knowledge can be gained about the interaction between the two. A wavelet cross-spectrum technique is introduced into the traditional Stokes parameter analysis. From this analysis it is shown that small-scale gravity waves possess distinctive polarization signatures. Further extension of the Stokes parameter analysis by a wave-averaging method is also proposed. The analysis using this method indicates that the turbulence production is closely related to an enhanced level of polarization and coherency in the two components of the horizontal wind in the gravity waves and that the turbulence surge is accompanied by a tendency for an instantaneous reduction of polarization and abrupt shift of horizontal wave vector of the progenitor gravity waves. These findings may be useful in the prediction of the occurrence of turbulence in association with gravity wave activities in the atmosphere.