The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale Model

Abstract Mesoscale numerical weather prediction models currently operate at kilometer‐scale and even sub‐kilometer‐scale resolutions. Although shallow cumulus convection is partly resolved at these resolutions, it is still common to use a shallow cumulus parameterization (SCP). Within the context of...

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Main Authors: A. C. M. Savazzi, L. Nuijens, W. deRooy, A. P. Siebesma
Format: Article
Language:English
Published: American Geophysical Union (AGU) 2025-02-01
Series:Journal of Advances in Modeling Earth Systems
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Online Access:https://doi.org/10.1029/2024MS004538
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author A. C. M. Savazzi
L. Nuijens
W. deRooy
A. P. Siebesma
author_facet A. C. M. Savazzi
L. Nuijens
W. deRooy
A. P. Siebesma
author_sort A. C. M. Savazzi
collection DOAJ
description Abstract Mesoscale numerical weather prediction models currently operate at kilometer‐scale and even sub‐kilometer‐scale resolutions. Although shallow cumulus convection is partly resolved at these resolutions, it is still common to use a shallow cumulus parameterization (SCP). Within the context of the EUREC4A model intercomparison project, we evaluate how the modeled mesoscale cloud field in the trades responds to parameterized or explicit shallow convection in the mesoscale model HARMONIE‐AROME. We simulate a region of 3,200 × 2,025 km2 east of Barbados using a grid spacing of 2.5 km for a 2 months period (1 January to 29 February 2020). We compare three configurations of HARMONIE‐AROME: (a) one with an active SCP (control), (b) one without parameterized momentum transport by shallow convection, and (c) one with an inactive SCP. The experiments produce different responses in the cloud field that are not incremental. With the SCP inactive, the model produces a warmer lower troposphere with many smaller but deeper clouds that precipitate more. Along with stronger resolved eddy kinetic energy, wider and stronger shallow meridional overturning circulations develop. In the configuration without parameterized momentum transport by shallow convection, the eddy‐diffusivity scheme effectively takes over the missing transport in the sub‐cloud layer up to ∼ 800 m. Above that level, horizontal wind variance increases as the total momentum flux decreases, enhancing eddy kinetic energy at scales of 2.5 km and larger. In contrast to the configuration with an inactive SCP, cloud top heights hardly deepen, but stratiform cloudiness below the inversion and mean cloud size increase.
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spelling doaj-art-b5935396b5f74dca90ff5b9e9125dd542025-08-20T02:09:29ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662025-02-01172n/an/a10.1029/2024MS004538The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale ModelA. C. M. Savazzi0L. Nuijens1W. deRooy2A. P. Siebesma3Delft University of Technology Delft The NetherlandsDelft University of Technology Delft The NetherlandsRoyal Netherlands Meteorological Institute (KNMI) De Bilt The NetherlandsDelft University of Technology Delft The NetherlandsAbstract Mesoscale numerical weather prediction models currently operate at kilometer‐scale and even sub‐kilometer‐scale resolutions. Although shallow cumulus convection is partly resolved at these resolutions, it is still common to use a shallow cumulus parameterization (SCP). Within the context of the EUREC4A model intercomparison project, we evaluate how the modeled mesoscale cloud field in the trades responds to parameterized or explicit shallow convection in the mesoscale model HARMONIE‐AROME. We simulate a region of 3,200 × 2,025 km2 east of Barbados using a grid spacing of 2.5 km for a 2 months period (1 January to 29 February 2020). We compare three configurations of HARMONIE‐AROME: (a) one with an active SCP (control), (b) one without parameterized momentum transport by shallow convection, and (c) one with an inactive SCP. The experiments produce different responses in the cloud field that are not incremental. With the SCP inactive, the model produces a warmer lower troposphere with many smaller but deeper clouds that precipitate more. Along with stronger resolved eddy kinetic energy, wider and stronger shallow meridional overturning circulations develop. In the configuration without parameterized momentum transport by shallow convection, the eddy‐diffusivity scheme effectively takes over the missing transport in the sub‐cloud layer up to ∼ 800 m. Above that level, horizontal wind variance increases as the total momentum flux decreases, enhancing eddy kinetic energy at scales of 2.5 km and larger. In contrast to the configuration with an inactive SCP, cloud top heights hardly deepen, but stratiform cloudiness below the inversion and mean cloud size increase.https://doi.org/10.1029/2024MS004538shallow convective parameterizationconvective momentum transportmesoscale circulationsEUREC4aHARMONIE‐AROMEcloud organisation
spellingShingle A. C. M. Savazzi
L. Nuijens
W. deRooy
A. P. Siebesma
The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale Model
Journal of Advances in Modeling Earth Systems
shallow convective parameterization
convective momentum transport
mesoscale circulations
EUREC4a
HARMONIE‐AROME
cloud organisation
title The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale Model
title_full The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale Model
title_fullStr The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale Model
title_full_unstemmed The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale Model
title_short The Influence of Parameterized Shallow Convection on Trade‐Wind Clouds and Circulations in the HARMONIE‐AROME Mesoscale Model
title_sort influence of parameterized shallow convection on trade wind clouds and circulations in the harmonie arome mesoscale model
topic shallow convective parameterization
convective momentum transport
mesoscale circulations
EUREC4a
HARMONIE‐AROME
cloud organisation
url https://doi.org/10.1029/2024MS004538
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