Preprints
https://doi.org/10.5194/egusphere-2024-2143
https://doi.org/10.5194/egusphere-2024-2143
17 Jul 2024
 | 17 Jul 2024

Atmospheric Deserts: Detection and Consequences

Fiona Fix, Georg Johann Mayr, Achim Zeileis, Isabell Kathrin Stucke, and Reto Stauffer

Abstract. We introduce the concept of atmospheric deserts (ADs), air masses that are advected away from hot and dry convective boundary layers in semi-arid or desert source regions. They can be expected to eliminate cloudiness, cause heat to build up in the target region, suppress thunderstorm formation in their centre and boost thunderstorm formation at their edges. A direct detection method, tracing the AD from source to target using Lagrangian trajectories is developed.

We illustrate this new concept of ADs with a case study in Europe from mid-June 2022. With the Lagrangian analysis tool (LAGRANTO) approximately 200 million trajectories are calculated, tracking the path of the air mass and the development of its properties as it progresses from North Africa towards and across Europe over the course of five days. k-means-clustering identifies four typical pathways that the trajectories follow. For one of the pathways, the air nearly conserves its well-mixed properties. Diabatic processes of radiative cooling, latent heating due to condensation, and cooling due to re-evaporation of precipitation, however, modify the air along the other pathways.

The case study demonstrates how ADs influence the weather in the target region. Thunderstorms are mainly absent in the centre of the AD, but erupt along a line parallel to its boundary. At this edge of the AD and the surface front, lifting occurs, causing the formation of thunderstorms. The AD does not reside directly above the local boundary layer for long enough to be the main cause for the heat wave affecting large parts of Europe, but may contribute to it. Subsidence heating of another air stream, was identified as one possible reason for the increased near-surface temperatures.

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.
Fiona Fix, Georg Johann Mayr, Achim Zeileis, Isabell Kathrin Stucke, and Reto Stauffer

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2143', Anonymous Referee #1, 15 Aug 2024
    • AC1: 'Reply on RC1', Fiona Fix, 30 Aug 2024
  • RC2: 'Comment on egusphere-2024-2143', Anonymous Referee #2, 06 Sep 2024
    • EC1: 'Reply on RC2', Peter Knippertz, 15 Sep 2024
      • AC2: 'Reply on EC1', Fiona Fix, 02 Oct 2024
        • EC2: 'Reply on AC2', Peter Knippertz, 05 Oct 2024

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2143', Anonymous Referee #1, 15 Aug 2024
    • AC1: 'Reply on RC1', Fiona Fix, 30 Aug 2024
  • RC2: 'Comment on egusphere-2024-2143', Anonymous Referee #2, 06 Sep 2024
    • EC1: 'Reply on RC2', Peter Knippertz, 15 Sep 2024
      • AC2: 'Reply on EC1', Fiona Fix, 02 Oct 2024
        • EC2: 'Reply on AC2', Peter Knippertz, 05 Oct 2024
Fiona Fix, Georg Johann Mayr, Achim Zeileis, Isabell Kathrin Stucke, and Reto Stauffer

Interactive computing environment

Code used for the paper "Atmospheric Deserts: Detection and Consequences" Fiona Fix https://doi.org/10.5281/zenodo.12663679

Fiona Fix, Georg Johann Mayr, Achim Zeileis, Isabell Kathrin Stucke, and Reto Stauffer

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Short summary
“Atmospheric deserts” (ADs) are air masses that are transported away from hot, dry regions. Our study introduces this new concept. ADs can suppress or boost thunderstorms, and potentially contribute to the formation of heat waves, which makes them relevant for forecasting extreme events. Using a novel detection method, we follow the AD directly from North Africa to Europe for a case in June 2022, allowing us to analyze the air mass at any time and investigate how it is modified along the way.