The Cold-Air Outbreaks in the Marine Boundary Layer Experiment model-observation intercomparison project (COMBLE-MIP) – Part 1: Model specification, observational constraints, and preliminary findings

Models struggle to represent the coupled microphysical, turbulent and radiative processes within widespread, long-lived marine cold-air outbreak (CAO) cloud fields, contributing to forecast and climate biases. Here we combine ground-based and satellite measurements to initialize and constrain large-eddy simulations (LES) of cloud field evolution with distance downwind from the marginal ice zone during a strong, highly supercooled and convective CAO observed during the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE). LES results are compared with large-scale models run in single-column model (SCM) mode, providing an observation-constrained framework for large-scale model evaluation and future improvements. All models reproduce rapid cloud formation off the ice edge, and a monotonic ascent of downwind cloud-top heights, closely linked with time-integrated surface heat fluxes. LES generally reproduce domain-mean observational targets using a modest test domain (25×25 km 2 ), and a larger domain (125×125 km 2 ) enables better reproducing the observed growth of convective cell sizes. In realistic mixed-phase LES compared with liquid-only simulations, ice processes lead to thinner, broken cloud decks and substantially reduced cloud radiative effects on top-of-atmosphere longwave fluxes. By contrast, mixed-phase SCM simulations generally underpredict the radiative impact of ice, primarily owing to insufficient reduction of cloud cover. Results indicate that cellular cloud structure is qualitatively captured by LES, and thus LES could provide guidance to improvement of large-scale model physics schemes. Follow-on work will extend these results to larger domains, apply objective analysis of mesoscale structure, and include prognostic aerosol properties for droplet and heterogeneous ice formation.

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Journal
Atmospheric chemistry and physics
Published
2026-09-22
DOI
https://doi.org/10.5194/acp-26-13267-2026
Primary Topic
Atmospheric aerosols and clouds
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article
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article

The Cold-Air Outbreaks in the Marine Boundary Layer Experiment model-observation intercomparison project (COMBLE-MIP) – Part 1: Model specification, observational constraints, and preliminary findings

Lulin Xue, Anu Gupta, Peter Kuma, Étienne Vignon et al.
Atmospheric chemistry and physics
Atmospheric aerosols and clouds
article

The Cold-Air Outbreaks in the Marine Boundary Layer Experiment model-observation intercomparison project (COMBLE-MIP) – Part 1: Model specification, observational constraints, and preliminary findings

Lulin Xue, Anu Gupta, Peter Kuma, Étienne Vignon, Bart Geerts, Jan Chylik, Alejandro Baró Pérez, Kamal Kant Chandrakar, Mikhail Ovchinnikov, Timothy W. Juliano, Dmitry Chechin, Roel Neggers, Xue Zheng, Ann M. Fridlind, Niklas Schnierstein, Luisa Ickes, Peng Wu, Israel Silber, Michael Tjernström, Anna Possner, Rostislav Yu. Fadeev, Lea Raillard, David Painemal, Michail Karalis, Evgeny V. Mortikov, Martin Köhler, Shin‐ichiro Shima, Christian Philipp Lackner, Gregory S. Elsaesser, Gunilla Svensson, Florian Tornow, Branko Kosović, Sami Romakkaniemi, Tomi Raatikainen, Andrew S. Ackerman, Nikita Silin, Weiwei Li, Hugh Morrison, Andrey Debolskiy, Peter Bogenschutz, Meng Zhang, Mikhail Tolstykh
article en

Abstract

Models struggle to represent the coupled microphysical, turbulent and radiative processes within widespread, long-lived marine cold-air outbreak (CAO) cloud fields, contributing to forecast and climate biases. Here we combine ground-based and satellite measurements to initialize and constrain large-eddy simulations (LES) of cloud field evolution with distance downwind from the marginal ice zone during a strong, highly supercooled and convective CAO observed during the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE). LES results are compared with large-scale models run in single-column model (SCM) mode, providing an observation-constrained framework for large-scale model evaluation and future improvements. All models reproduce rapid cloud formation off the ice edge, and a monotonic ascent of downwind cloud-top heights, closely linked with time-integrated surface heat fluxes. LES generally reproduce domain-mean observational targets using a modest test domain (25×25 km 2 ), and a larger domain (125×125 km 2 ) enables better reproducing the observed growth of convective cell sizes. In realistic mixed-phase LES compared with liquid-only simulations, ice processes lead to thinner, broken cloud decks and substantially reduced cloud radiative effects on top-of-atmosphere longwave fluxes. By contrast, mixed-phase SCM simulations generally underpredict the radiative impact of ice, primarily owing to insufficient reduction of cloud cover. Results indicate that cellular cloud structure is qualitatively captured by LES, and thus LES could provide guidance to improvement of large-scale model physics schemes. Follow-on work will extend these results to larger domains, apply objective analysis of mesoscale structure, and include prognostic aerosol properties for droplet and heterogeneous ice formation.

Atmospheric chemistry and physicsVol. 26(18)
NSF National Center for Atmospheric Research (US), Goethe University Frankfurt (DE), Goddard Institute for Space Studies (US), Lawrence Livermore National Laboratory (US), University of Wyoming (US), Finnish Meteorological Institute (FI), Swedish Meteorological and Hydrological Institute (SE), Centre National de la Recherche Scientifique (FR), Hydrometeorological Research Centre of Russian Federation (RU), Langley Research Center (US), École Polytechnique (FR), Pacific Northwest National Laboratory (US), Stockholm University (SE), Deutscher Wetterdienst (DE), University of Cologne (DE), University of Hyogo (JP), Lomonosov Moscow State University (RU), Université Paris Sciences et Lettres (FR), Johns Hopkins University Applied Physics Laboratory (US), École Normale Supérieure - PSL (FR), Sorbonne Université (FR), Institute of Numerical Mathematics (RU), Laboratoire de Météorologie Dynamique (FR), National Aeronautics and Space Administration (US), A.M. Obukhov Institute of Atmospheric Physics (RU), Institute of Mathematical Problems of Biology (RU), Bolin Centre for Climate Research (SE), École Polytechnique Fédérale de Lausanne (CH), Chalmers University of Technology (SE), Columbia University (US)
Life below water
Openalex Percentile: Top 14%
Atmospheric aerosols and clouds
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