Preprints
https://doi.org/10.5194/egusphere-2025-3005
https://doi.org/10.5194/egusphere-2025-3005
27 Jun 2025
 | 27 Jun 2025

Non-zonal gravity wave forcing of the Northern Hemisphere winter circulation and effects on middle atmosphere dynamics

Sina Mehrdad, Sajedeh Marjani, Dörthe Handorf, and Christoph Jacobi

Abstract. Gravity waves (GWs) are a major yet poorly constrained driver of middle‑atmosphere dynamics. Using the high‑top UA‑ICON global circulation model, we conducted a set of six-member ensemble simulations in which orographic GW drag was selectively intensified over three Northern Hemisphere hotspots – the Himalayas (HI), Northwest America (NA), and East Asia (EA) – to assess their long‑term dynamical impacts on the stratosphere. The imposed forcing generated distinctive vertical–horizontal drag structures in each region, yet produced a coherent hemispheric response. Resolved waves compensated the local drag through compensation mechanisms. In all three cases, added westward momentum suppressed upward and equatorward propagation of planetary waves, particularly of wavenumber 1, strengthening westerlies in the upper stratosphere–mesosphere. The frequency of sudden stratospheric warmings remained unchanged in the HI and NA experiments, but increased notably in EA, while the ratio of split to displacement events was unaffected. These results highlight the sensitivity of stratospheric variability to non-zonal GW forcing and underscore the importance of improving our understanding of GW–climate interactions. The simulation dataset presented here offers a valuable resource for future studies on gravity wave–induced variability in the climate system.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
Share
Sina Mehrdad, Sajedeh Marjani, Dörthe Handorf, and Christoph Jacobi

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-3005', Anonymous Referee #1, 18 Aug 2025
  • RC2: 'Comment on egusphere-2025-3005', Corwin Wright, 20 Aug 2025
Sina Mehrdad, Sajedeh Marjani, Dörthe Handorf, and Christoph Jacobi
Sina Mehrdad, Sajedeh Marjani, Dörthe Handorf, and Christoph Jacobi

Viewed

Total article views: 351 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
291 44 16 351 31 47
  • HTML: 291
  • PDF: 44
  • XML: 16
  • Total: 351
  • BibTeX: 31
  • EndNote: 47
Views and downloads (calculated since 27 Jun 2025)
Cumulative views and downloads (calculated since 27 Jun 2025)

Viewed (geographical distribution)

Total article views: 338 (including HTML, PDF, and XML) Thereof 338 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 30 Aug 2025
Download
Short summary
Wind flowing over mountains creates wave-like patterns aloft that can influence the atmosphere higher up in the stratosphere and mesosphere. In this study, we intensified these waves over specific regions like the Himalayas and Rocky Mountains and examined the resulting climate effects. We found that this can shift global wind patterns and even impact extreme events near the poles, showing how small regional changes in stratospheric wind patterns can influence the broader climate system.
Share