Acoustic waves generated by gusty flow over hilly terrain

Abstract

[1] We examine the generation of acoustic waves by gusty flow over hilly terrain. We use simple theoretical models of the interaction between terrain and eddies and a linear model of acoustic-gravity wave propagation. The calculations presented here suggest that over a dense array of geographically extensive sources orographically generated vertically propagating acoustic waves can be a significant cause of thermospheric heating. This heating may account in good part for the thermospheric hot spot near the Andes reported by Meriwether et al. (1996Meriwether et al. ( , 1997.Citation: Walterscheid, R. L., and M. P. Hickey (2005), Acoustic waves generated by gusty flow over hilly terrain,

Thermospheric mass density: A review

“…Sources are similar to those of gravity waves: wind/topography interaction in the troposphere (Walterscheid and Hickey, 2005), interfering ocean waves (Rind, 1977), seismic activity, and localized auroral heating in the high-latitude thermosphere (Wilson, 2012;Pasko, 2012;Deng and Ridley, 2014b). Rind (1977) estimated that 0.2 Hz ocean-generated waves deposit about as much energy into the thermosphere as gravity waves do.…”

“…Rind (1977) estimated that 0.2 Hz ocean-generated waves deposit about as much energy into the thermosphere as gravity waves do. Walterscheid and Hickey (2005) calculated that dissipation of wind/topography-generated waves with periods of 1-5 minutes may account for anomalously high temperatures observed in the upper thermosphere over the Andes.…”

Wave heating and Jeans escape in the Martian upper atmosphere

“…The mean temperature and the associated Brunt‐Väisälä and acoustic cutoff periods are shown in Figure for 45°N. Both Brunt‐Väisälä and acoustic cutoff periods are evaluated by taking into account the variations of temperature and mean molecular weight with height [ Walterscheid and Hecht , ; Walterscheid and Hickey , , ]. The temperature (solid curve) increases from the minimum at the mesopause (~110 km) to a constant with a value of around 260 K above ~ 160 km.…”

“…[]. Perhaps this is related to the filtering of slower gravity waves generated by steep terrain and the more extensive regions of hilly terrain that may serve as sources for fast gravity and acoustic waves [ Walterscheid and Hickey , ].…”

Infrasound from tropospheric sources: Impact on mesopause temperature?

“…While several works have been carried out within the last years to address especially the effects of infrasound on the thermosphere/ionosphere altitude region (e.g. Rind, 1977;Schubert et al, 2005;Walterscheid and Hickey, 2005;Krasnov et al, 2007), the focus of this study is on the upper mesosphere altitude region (approximately 80-100 km). Various authors already investigated the effects of acoustic heating on this altitude region (e.g.…”