Supercell thunderstorms in complex topography - how mountain valleys with lakes can increase occurrence frequency

Feldmann, Monika; Rotunno, Richard; Germann, Urs; Berne, Alexis (2024). Supercell thunderstorms in complex topography - how mountain valleys with lakes can increase occurrence frequency. Monthly Weather Review, 152(2), pp. 471-489. American Meteorological Society 10.1175/MWR-D-22-0350.1

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This study investigates the effects of lakes in mountainous terrain on the evolution of supercell thunderstorms. With a newly developed radar-based, mesocyclone-detection algorithm, a recent study has characterized the occurrence and evolution of supercell thunderstorms in the Swiss Alpine region. That study highlights the influence of orography on both storm intensity and occurrence frequency. To disentangle the different influential factors, an idealized modeling framework is established here using the mesoscale model CM1. The modeling scenarios are based on a high-CAPE environment with unidirectional shear, where a warm bubble serves to initiate the convection. Mimicking the environment of the southern Prealps in central Europe, scenarios with a high mountain ridge, valleys and lakes are explored. The effect on the supercells of the slopes, high-altitude terrain and moisture sources emphasizes the highly localized nature of terrain effects, leading to a heterogeneous intensity lifecycle with transitory enhancement and weakening of the supercell. The dynamic and thermodynamic impact of mountain valleys with lakes increases the range of atmospheric conditions that supports supercellular development through horizontal vorticity production, increased storm relative helicity and higher moisture content. This influence results in a systematic location dependence of the frequency, intensity and lifetime of supercells, as also found in observations.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Impact
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography
08 Faculty of Science > Institute of Geography > Physical Geography
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR) > NCCR Climate

UniBE Contributor:

Feldmann, Monika

Subjects:

500 Science > 530 Physics
500 Science > 550 Earth sciences & geology
900 History > 910 Geography & travel

ISSN:

0027-0644

Publisher:

American Meteorological Society

Funders:

[UNSPECIFIED] EDEC Mobility Grant of EPFL ; [UNSPECIFIED] Graduate Visitor Programm of National Center for Atmospheric Research ; [4] Swiss National Science Foundation

Language:

English

Submitter:

Lara Maude Zinkl

Date Deposited:

11 Jan 2024 08:14

Last Modified:

24 Jan 2024 00:16

Publisher DOI:

10.1175/MWR-D-22-0350.1

BORIS DOI:

10.48350/191437

URI:

https://boris.unibe.ch/id/eprint/191437

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