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Abstract We analyze the gravity waves (GWs) observed by a Rayleigh lidar at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) (16.08°E, 69.38°N) in Norway atz ∼ 20–85 km on 12–14 January 2016. These GWs propagate upward and downward away fromzknee = 57 and 64 km at a horizontally‐displaced location with periodsτr ∼ 5–10 hr and vertical wavelengthsλz ∼ 9–20 km. Because the hodographs are distorted, we introduce an alternative method to determine the GW parameters. We find that these GWs are medium to large‐scale, and propagate north/northwestward with intrinsic horizontal phase speeds of ∼35–65 m/s. Since the GW parameters are similar above and belowzknee, these are secondary GWs created by local body forces (LBFs) south/southeast of ALOMAR. We use the nudged HIAMCM (HIgh Altitude Mechanistic general Circulation Model) to model these events. Remarkably, the model reproduces similar GW structures over ALOMAR, withzknee = 58 and 66 km. The event #1 GWs are created by a LBF at ∼35°E, ∼60°N, andz ∼ 58 km. This LBF is created by the breaking and dissipation of primary GWs generated and amplified by the imbalance of the polar night jet below the wind maximum; the primary GWs for this event are created atz ∼ 25–35 km at 49–53°N. We also find that the HIAMCM GWs agree well with those observed by the Atmospheric InfraRed Sounder (AIRS) satellite, and that those AIRS GWs south and north of ∼50°N over Europe are mainly mountain waves and GWs from the polar vortex, respectively.
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Orographic Primary and Secondary Gravity Waves in the Middle Atmosphere From 16‐Year SABER Observations
Abstract The 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 toz ~ 55 km. Using wind and topographic data, we show that orographic GWs break above the peak height of the stratospheric jet. Atz ~ 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.
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- Award ID(s):
- 1834222
- PAR ID:
- 10447415
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 46
- Issue:
- 8
- ISSN:
- 0094-8276
- Page Range / eLocation ID:
- p. 4512-4522
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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