Horizontal structures of bow-shaped mountain wave trains seen in thermal infrared images of venusian clouds taken by Akatsuki LIR

Bow-shaped stationary gravity waves (mountain waves) have been observed in Venusian cloud images taken by the cameras onboard Akatsuki spacecraft. The are most pronounced thermal infrared Longwave Infrared Camera (LIR), and shown to appear at longitudes where high mountains exist. To better characterize mountain atmosphere, we applied a new analysis method LIR data. By averaging multiple sequentially obtained geographical coordinates, noise drifting features were suppressed emphasized, thereby identifying even weak wave whose amplitudes smaller than those identified previous studies. six highland regions, two of these not previously reported. Each packet extends both downstream upstream thousands kilometers from expected source region. Such characteristics might be attributed trapping horizontal propagation low-static stability layers below clouds.