Universität zu Köln

Burchart, Yannick ORCID: 0000-0001-6798-2596, Pospichal, Bernhard ORCID: 0000-0001-9517-8300 and Neggers, Roel A. J. ORCID: 0000-0001-9182-3050 (2025). Confronting Large‐Eddy Simulations With Stereo Camera Data by Means of Reconstructed Hemispheric Cloud Size Distributions. Journal of Advances in Modeling Earth Systems, 17 (7). pp. 1-26. Wiley. ISSN 1942-2466

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Abstract

[Artikel-Nr.: e2024MS004804] High‐resolution hemispheric camera images at a meteorological site in western Germany are used to analyze the multi‐dimensional spatial characteristics of continental cumulus cloud fields, and to evaluate Large‐Eddy Simulations on this aspect. Traditional non‐hemispheric cloud‐detecting instruments provide additional reference data. The main model‐observation comparison focuses on cloud size distributions (CSDs), employing two methods: (a) directly using three‐dimensional model fields, direct CSDs, and (b) using rendered hemispheric images of the model fields as produced by a camera simulator based on path‐tracing. In the latter method, both the real and rendered images are used to three‐dimensionally reconstruct the cloud fields, yielding hemispheric CSDs. Advantages of hemispheric comparisons over more classic approaches include (a) fair comparisons between model and data, and (b) full use of the enhanced resolutions and hemispheric spatial coverage of the camera imagery. Basic evaluation of the simulations demonstrates good agreement on thermodynamic structure and its diurnal cycle. Cloud heights and cloud cover are intercompared between the model, camera data and other instrumentation, providing insight into their structural differences. A consistent alignment is found between the hemispheric CSDs from both the model and the cameras. Power law fits reveal structurally lower exponents in hemispheric CSDs compared to non‐hemispheric CSDs, which particularly caution against directly comparing hemispheric CSDs to non‐hemispheric distributions. This result is robust for sample size and fitting method. These findings inform future use of hemispheric camera systems for studying cumulus cloud field morphology and model evaluation. Key Points: A hemispheric camera simulator is used to compare large‐eddy simulations with real‐world observations of shallow cumulus clouds over land 3D cloud reconstruction is applied to both real and rendered images, yielding intrinsically comparable cloud size distributions. These hemispheric size distributions agree well between model and observations, and follow distinct power law functional forms.

Item Type:	Article
Creators:	Creators Email ORCID ORCID Put Code Burchart, Yannick UNSPECIFIED https://orcid.org/0000-0001-6798-2596 UNSPECIFIED Pospichal, Bernhard UNSPECIFIED https://orcid.org/0000-0001-9517-8300 UNSPECIFIED Neggers, Roel A. J. UNSPECIFIED https://orcid.org/0000-0001-9182-3050 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-801490
Identification Number:	10.1029/2024MS004804
Journal or Publication Title:	Journal of Advances in Modeling Earth Systems
Volume:	17
Number:	7
Page Range:	pp. 1-26
Number of Pages:	26
Date:	14 July 2025
Publisher:	Wiley
ISSN:	1942-2466
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Geosciences > Institute for Geophysics and Meteorology
Subjects:	Earth sciences Geography and travel
['eprint_fieldname_oa_funders' not defined]:	Publikationsfonds UzK
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80149