Preprints
https://doi.org/10.5194/egusphere-2025-2474
https://doi.org/10.5194/egusphere-2025-2474
10 Jun 2025
 | 10 Jun 2025

The Frosty Frontier: Redefining the Tropopause as a transport barrier using the Relative Humidity over Ice

Philipp Reutter and Peter Spichtinger

Abstract. The tropopause acts as transport barrier between the troposphere and stratosphere. While common definitions rely on quantities conserved under adiabatic changes, diabatic effects, resulting from radiation, cloud processes or turbulence are also decisive for the tropopause structure. Therefore, we propose a new definition based on the vertical gradient of the relative humidity with respect to ice (RHi). RHi is the key variable for ice cloud formation and incorporates both diabatic and adiabatic processes. Based on high-resolution radio sonde data we can show that our definition reflects the nature of the tropopause as a transport barrier much better than conventional approaches. This is not only evident in individual vertical profiles, but also when looking at statistics of many profiles with a tropopause-relative height axis. Last but not least, the robust and simple calculation of our definition makes it an ideal tool for studies involving the tropopause.

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

Journal article(s) based on this preprint

20 Nov 2025
| Highlight paper
The frosty frontier: redefining the mid-latitude tropopause using the relative humidity over ice
Philipp Reutter and Peter Spichtinger
Atmos. Chem. Phys., 25, 16303–16314, https://doi.org/10.5194/acp-25-16303-2025,https://doi.org/10.5194/acp-25-16303-2025, 2025
Short summary Executive editor
Philipp Reutter and Peter Spichtinger

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-2474', Anonymous Referee #1, 23 Jul 2025
  • RC2: 'Comment on egusphere-2025-2474', Anonymous Referee #2, 24 Jul 2025
  • AC1: 'Comment on egusphere-2025-2474', Philipp Reutter, 24 Sep 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-2474', Anonymous Referee #1, 23 Jul 2025
  • RC2: 'Comment on egusphere-2025-2474', Anonymous Referee #2, 24 Jul 2025
  • AC1: 'Comment on egusphere-2025-2474', Philipp Reutter, 24 Sep 2025

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
AR by Philipp Reutter on behalf of the Authors (24 Sep 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (25 Sep 2025) by Martina Krämer
RR by Anonymous Referee #1 (06 Oct 2025)
RR by Anonymous Referee #2 (18 Oct 2025)
ED: Publish subject to minor revisions (review by editor) (20 Oct 2025) by Martina Krämer
AR by Philipp Reutter on behalf of the Authors (21 Oct 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to technical corrections (24 Oct 2025) by Martina Krämer
AR by Philipp Reutter on behalf of the Authors (28 Oct 2025)  Manuscript 

Journal article(s) based on this preprint

20 Nov 2025
| Highlight paper
The frosty frontier: redefining the mid-latitude tropopause using the relative humidity over ice
Philipp Reutter and Peter Spichtinger
Atmos. Chem. Phys., 25, 16303–16314, https://doi.org/10.5194/acp-25-16303-2025,https://doi.org/10.5194/acp-25-16303-2025, 2025
Short summary Executive editor
Philipp Reutter and Peter Spichtinger
Philipp Reutter and Peter Spichtinger

Viewed

Total article views: 870 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
799 53 18 870 11 30
  • HTML: 799
  • PDF: 53
  • XML: 18
  • Total: 870
  • BibTeX: 11
  • EndNote: 30
Views and downloads (calculated since 10 Jun 2025)
Cumulative views and downloads (calculated since 10 Jun 2025)

Viewed (geographical distribution)

Total article views: 863 (including HTML, PDF, and XML) Thereof 863 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 20 Nov 2025
Download

The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
We present a new technique to determine the tropopause based on the gradient of relative humidity over ice. This reflects the character of the tropopause as a transport barrier very well, both in individual vertical profiles and in the long-term average. The results of the investigations using radio sondes are also supported by theoretical considerations.
Share