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Cloud Botany: Shallow cumulus clouds in an ensemble of idealized large-domain large-eddy simulations of the trades
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  • Fredrik Jansson,
  • Martin Janssens,
  • Johanna H Grönqvist,
  • Pier Siebesma,
  • Franziska Glassmeier,
  • Jisk Jakob Attema,
  • Victor Azizi,
  • Masaki Satoh,
  • Yousuke Sato,
  • Hauke Schulz,
  • Tobias Kölling
Fredrik Jansson
TU Delft

Corresponding Author:[email protected]

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Martin Janssens
Wageningen University & Research
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Johanna H Grönqvist
Åbo Akademi University
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Pier Siebesma
TU Delft
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Franziska Glassmeier
TU Delft
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Jisk Jakob Attema
Netherlands eScience Center
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Victor Azizi
Netherlands eScience Center
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Masaki Satoh
University of Tokyo
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Yousuke Sato
Hokkaido University
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Hauke Schulz
University of Washington
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Tobias Kölling
Max Planck Institute for Meteorology
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Abstract

Small shallow cumulus clouds (< 1 km) over the tropical oceans appear to possess the ability to self-organise into mesoscale (10-100 km) patterns. To better understand the processes leading to such self-organized convection, we present Cloud Botany, an ensemble of 103 large-eddy simulations on domains of 150 km, produced by the Dutch Large Eddy Simulation (DALES) model on supercomputer Fugaku. Each simulation is run in an idealized, fixed, larger-scale environment, controlled by six free parameters. We vary these over characteristic ranges for the winter trades, including parameter combinations observed during the EUREC4A (Elucidating the role of clouds–circulation coupling in climate) field campaign. In contrast to simulation setups striving for maximum realism, Cloud Botany provides a platform for studying idealized, and therefore more clearly interpretable causal relationships between conditions in the larger-scale environment and patterns in mesoscale, self-organized shallow convection. We find that any simulation that supports cumulus clouds eventually develops mesoscale patterns in their cloud fields. We also find a rich variety in these patterns as our control parameters change, including cold pools lined by cloudy arcs, bands of cross-wind clouds and aggregated patches, sometimes topped by thin anvils. Many of these features are similar to cloud patterns found in nature. The published data set consists of raw simulation output on full 3D grids and 2D cross-sections, as well as post-processed quantities aggregated over the vertical (2D), horizontal (1D) and all spatial dimensions (time-series). The data set is directly accessible from Python through the use of the EUREC4A intake catalog.
04 May 2023Submitted to ESS Open Archive
04 May 2023Published in ESS Open Archive