A High‐Resolution Whole‐Atmosphere Model With Resolved Gravity Waves and Specified Large‐Scale Dynamics in the Troposphere and Stratosphere
Abstract
We present a new version of the HIgh Altitude Mechanistic general Circulation Model (HIAMCM) with specified dynamics. We utilize a spectral method that nudges only the large‐scale flow to MERRA‐2 reanalysis. The nudged HIAMCM simulates gravity waves (GWs) down to horizontal wavelengths of about 200 km from the troposphere to the thermosphere like the free‐running model, including the generation of secondary and tertiary GWs. Case studies show that the simulated large‐scale GWs are consistent with those in the reanalysis, while the medium‐scale GWs compare well with observations in the northern winter 2016 stratosphere from the Atmospheric InfraRed Sounder (AIRS). GWs having wavelengths larger than about 1,350 km can be described with the nonlinear balance equation. The GWs relevant in the stratosphere, however, have smaller scales and require a different approach. We propose that the GW amplification due to kinetic energy transfer from the large‐scale flow combined with GW potential energy flux convergence helps to identify the mesoscale GW sources due to spontaneous emission. The GW amplification is strongest in the region of maximum large‐scale vertical wind shear in the mid‐stratosphere. Maps of the time‐averaged stratospheric GW activity simulated by the HIAMCM and computed from AIRS satellite data show a persistent hot spot over Europe during January 2016. At about 40 km, the average GW amplitudes are maximum in the region of fastest large‐scale flow. We argue that refraction of GWs originating in the troposphere, as well as GWs from spontaneous emission in the stratosphere contribute to this effect.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 20, 2022
- Source ID
- 10.1029/2021jd035018
Entities
People
- Christoph Zülicke
- Erich Becker
- Katrina Bossert
- Lars Hoffmann
- Sharon L. Vadas
- V. Lynn Harvey
Organizations
- Arizona State University
- Defense Advanced Research Projects Agency
- German Research Foundation
- Jülich Supercomputing Centre
- Northwest Research Associates
- University of Rostock