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Title: The Role of the Polar Vortex Jet for Secondary and Higher‐Order Gravity Waves in the Northern Mesosphere and Thermosphere During 11–14 January 2016
Abstract

We analyze the gravity waves (GWs) from the ground to the thermosphere during 11–14 January 2016 using the nudged HI Altitude Mechanistic general Circulation Model. We find that the entrance, core and exit regions of the polar vortex jet are important for generating primary GWs and amplifying GWs from below. These primary GWs dissipate in the upper stratosphere/lower mesosphere and deposit momentum there; the atmosphere responds by generating secondary GWs. This process is repeated, resulting in medium to large‐scale higher‐order, thermospheric GWs. We find that the amplitudes of the secondary/higher‐order GWs from sources below the polar vortex jet are exponentially magnified. The higher‐order, thermospheric GWs have concentric ring, arc‐like and planar structures, and spread out latitudinally to 10 − 90°N. Those GWs with the largest amplitudes propagate against the background wind. Some of the higher‐order GWs generated over Europe propagate over the Arctic region then southward over the US to ∼15–20°N daily at ∼14 − 24 UT (∼9 − 16 LT) due to the favorable background wind. These GWs have horizontal wavelengthsλH ∼ 200 − 2,200 km, horizontal phase speedscH ∼ 165 − 260 m/s, and periodsτr ∼ 0.3 − 2.4 hr. Such GWs could be misidentified as being generated by auroral activity. The large‐scale, higher‐order GWs are generated in the lower thermosphere and propagate southwestward daily across the northern mid‐thermosphere at ∼8–16 LT withλH ∼ 3,000 km andcH ∼ 650 m/s. We compare the simulated GWs with those observed by AIRS, VIIRS/DNB, lidar and meteor radars and find reasonable to good agreement. Thus the polar vortex jet is important for facilitating the global generation of medium to large‐scale, higher‐order thermospheric GWs via multi‐step vertical coupling.

 
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Award ID(s):
1832988 2329957
PAR ID:
10553734
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
Journal of Geophysical Research: Space Physics
Date Published:
Journal Name:
Journal of Geophysical Research: Space Physics
Volume:
129
Issue:
9
ISSN:
2169-9380
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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