Preprints
https://doi.org/10.5194/egusphere-2024-2112
https://doi.org/10.5194/egusphere-2024-2112
16 Jul 2024
 | 16 Jul 2024

Synoptic perspective on the conversion and maintenance of local available potential energy in extratropical cyclones

Marc Federer, Lukas Papritz, Michael Sprenger, and Christian M. Grams

Abstract. Extratropical cyclones are the predominant weather system in the midlatitudes. They intensify through baroclinic instability, a process in which available potential energy (APE) is converted into kinetic energy (KE). While the planetary-scale conversion of APE to KE is well understood as a mechanism for maintaining the general atmospheric circulation against dissipation, the synoptic-scale perspective on this conversion is less explored. In this study, we analyze the three-dimensional distribution of APE and the physical processes that consume APE for an illustrative case study and a climatology of 285 intense North Atlantic extratropical cyclones in the winters 1979–2021 using the ERA5 reanalysis. We utilize a recently introduced local APE framework that allows APE to be quantified at the level of individual air parcels. The geographical APE distribution is shown to be controlled by the large-scale upper-level circulation. Cyclones draw energy from the upper-tropospheric polar APE reservoir along with the development of the associated upper-level trough. This upper-level APE is converted into KE by air descending along the trough's western flank and acts as the incipient cyclone's primary source of KE. Conversely, KE is converted back into APE during the ascent ahead of the trough, reflecting the deceleration of air parcels as they exit the cyclone region. The diabatic dissipation of APE due to surface sensible heat fluxes along the Gulf Stream front is small compared to the adiabatic conversion of APE to KE, since most of the APE is concentrated and consumed in the middle to upper troposphere and cannot be exposed to surface diabatic forcing. In conclusion, by employing a local APE framework, this study provides a detailed investigation of the synoptic dynamics linking extratropical cyclones and planetary-scale energetics.

Competing interests: At least one of the (co-)authors is a member of the editorial board of Weather and Climate Dynamics.

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 preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint

18 Feb 2025
| Highlight paper
Synoptic perspective on the conversion and maintenance of local available potential energy in extratropical cyclones
Marc Federer, Lukas Papritz, Michael Sprenger, and Christian M. Grams
Weather Clim. Dynam., 6, 211–230, https://doi.org/10.5194/wcd-6-211-2025,https://doi.org/10.5194/wcd-6-211-2025, 2025
Short summary Executive editor
Marc Federer, Lukas Papritz, Michael Sprenger, and Christian M. Grams

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2024-2112', Kevin Bowley, 15 Aug 2024
  • RC1: 'Comment on egusphere-2024-2112', Kevin A. Bowley, 16 Aug 2024
  • RC2: 'Comment on egusphere-2024-2112', Lance F. Bosart, 25 Aug 2024
  • AC1: 'Final author comments on egusphere-2024-2112', Marc Federer, 02 Oct 2024

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2024-2112', Kevin Bowley, 15 Aug 2024
  • RC1: 'Comment on egusphere-2024-2112', Kevin A. Bowley, 16 Aug 2024
  • RC2: 'Comment on egusphere-2024-2112', Lance F. Bosart, 25 Aug 2024
  • AC1: 'Final author comments on egusphere-2024-2112', Marc Federer, 02 Oct 2024

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Marc Federer on behalf of the Authors (08 Nov 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (12 Nov 2024) by Juerg Schmidli
RR by Kevin A. Bowley (03 Dec 2024)
ED: Publish as is (16 Dec 2024) by Juerg Schmidli
AR by Marc Federer on behalf of the Authors (23 Dec 2024)

Journal article(s) based on this preprint

18 Feb 2025
| Highlight paper
Synoptic perspective on the conversion and maintenance of local available potential energy in extratropical cyclones
Marc Federer, Lukas Papritz, Michael Sprenger, and Christian M. Grams
Weather Clim. Dynam., 6, 211–230, https://doi.org/10.5194/wcd-6-211-2025,https://doi.org/10.5194/wcd-6-211-2025, 2025
Short summary Executive editor
Marc Federer, Lukas Papritz, Michael Sprenger, and Christian M. Grams
Marc Federer, Lukas Papritz, Michael Sprenger, and Christian M. Grams

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

This study provides a novel Lagrangian perspective on cyclogenesis grounded in atmospheric energetics. While the energetics framework is commonly used to understand the planetary scale circulation, its application to synoptic scales is less explored. The authors establish a close connection between extratropical baroclinic zones and local available potential energy, and further analyze air parcel trajectories to link conversions between potential and kinetic energy to specific features of the developing cyclones. The results of this study offer insights into the local, synoptic and large scale contributions to cyclogenesis that are relevant for diverse disciplines in atmospheric and climate sciences.
Short summary
Although extratropical cyclones in the North Atlantic are among the most impactful midlatitude weather systems, the potential for their growth on synoptic scales is not well understood. Here we show how they convert potential into kinetic energy through the descent of cold upper-tropospheric air from high latitudes. Surface processes, such as ocean heat exchange, have a smaller effect. Understanding these dynamics helps to explain the processes that maintain storm tracks.
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