Atmospheric Gravity Waves in the Red Sea: a new hotspot

The region of the Middle East around the Red Sea (between 32°E and 44°E longitude and 12°N and 28°N latitude) is a currently undocumented hotspot for atmospheric gravity waves (AGWs). Satellite imagery shows evidence that this region is prone to relatively high occurrence of AGWs compared to other areas in the world, and reveals the characteristics of these waves. The favorable wave propagation conditions in this region are illustrated with a typical case of an atmospheric gravity wave propagating in the lower troposphere over the sea, together with the corresponding Scorer parameter and comparison with a weakly nonlinear long wave theory. Nonlinear wave theory gives phase speed and amplitude values which seem to fit within typical values for observed AGWs, with the Benjamin-Davis-Ono theory performing slightly better than Kortewegde Vries theory as far as measured phase speeds are concerned. ERS-SAR and EnvisatASAR satellite data analysis between 1993 and 2008 reveals signatures consistent with horizontally propagating large-scale internal waves. These signatures are more frequently observed between April and September, although they also occur during the rest of the year, and their spatial coverage includes the entire Red Sea. The region’s (seasonal) propagation conditions for AGWs, based upon average vertical atmospheric stratification profiles suggest that many of the signatures identified in the satellite images are atmospheric internal waves.