Orographic Primary and Secondary Gravity Waves in the Middle Atmosphere From 16‐Year SABER Observations

Abstract

AbstractThe seasonal and height dependencies of the orographic primary and larger‐scale secondary gravity waves (GWs) have been studied using the temperature profiles measured by Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) from 2002 to 2017. At ~40°S and during Southern Hemisphere winter, there is a strong GW peak over the Andes mountains that extend to z ~ 55 km. Using wind and topographic data, we show that orographic GWs break above the peak height of the stratospheric jet. At z ~ 55–65 km, GW breaking and momentum deposition create body forces that generate larger‐scale secondary GWs; we show that these latter GWs form a wide peak above 65 km with a westward tilt. At middle latitudes during summer in the respective hemisphere, orographic GW breaking also generates larger‐scale secondary GWs that propagate to higher altitudes. Both orographic primary and larger‐scale secondary GWs are likely responsible for most of the non‐equatorial peaks of the persistent global distribution of GWs in SABER.