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Title: Numerical Modeling of the Generation of Tertiary Gravity Waves in the Mesosphere and Thermosphere During Strong Mountain Wave Events Over the Southern Andes
Abstract

We investigate the effects on the mesosphere and thermosphere from a strong mountain wave (MW) event over the wintertime Southern Andes using a gravity wave (GW)‐resolving global circulation model. During this event, MWs break and attenuate atz∼50–80 km, thereby creating local body forces that generate large‐scale secondary GWs having concentric ring structure with horizontal wavelengthsλH=500–2,000 km, horizontal phase speedscH=70–100 m/s, and periodsτr∼3–10 hr. These secondary GWs dissipate in the upper mesosphere and thermosphere, thereby creating local body forces. These forces have horizontal sizes of 180–800 km, depending on the constructive/destructive interference between wave packets and the overall sizes of the wave packets. The largest body force is atz=80–130 km, has an amplitude of ∼2,400 m/s/day, and is located ∼1,000 km east of the Southern Andes. This force excites medium‐ and large‐scale “tertiary GWs” having concentric ring structure, withλHincreasing with radius from the centers of the rings. Near the Southern Andes, these tertiary GWs havecH=120–160 m/s,λH=350–2,000 km, andτr∼4–9 hr. Some of the larger‐λHtertiary GWs propagate to the west coast of Africa with very large phase speeds ofcH≃420 m/s. The GW potential energy density increases exponentially atz∼95–115 km, decreases atz∼115–125 km where most of the secondary GWs dissipate, and increases again atz>125 km from the tertiary GWs. Thus, strong MW events result in the generation of medium‐ to large‐scale fast tertiary GWs in the mesosphere and thermosphere via this multistep vertical coupling mechanism.

 
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Award ID(s):
1832988
NSF-PAR ID:
10372143
Author(s) / Creator(s):
 ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Journal of Geophysical Research: Space Physics
Volume:
124
Issue:
9
ISSN:
2169-9380
Page Range / eLocation ID:
p. 7687-7718
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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