Abstract
Previous study of shallow convection has generally suffered from having to balance domain size with resolution, resulting in high-resolution studies which do not capture large-scale behaviour of the cloud fields. In this work we hope to go some way towards addressing this by carrying out cloud-resolving simulations on large domains. Simulations of trade wind cumulus are carried out using the Met Office Unified Model (UM), based on a case study from the Rain In Cumulus over the Ocean (RICO) field campaign. The UM is run with a nested domain of 500 km with 500 m resolution, in order to capture the large-scale behaviour of the cloud field, and with a double-moment interactive microphysics scheme. Simulations are run using baseline aerosol profiles based on observations from RICO, which are then perturbed. We find that the aerosol perturbations result in changes to the convective behaviour of the cloud field, with higher aerosol leading to an increase (decrease) in the number of deeper (shallower) clouds. However, despite this deepening, there is little increase in the frequency of higher rain rates. This is in contrast to the findings of previous work making use of idealised simulation setups. In further contrast, we find that increasing aerosol results in a persistent increase in domain mean liquid water path and decrease in precipitation, with little impact on cloud fraction.
| Original language | American English |
|---|---|
| Pages (from-to) | 13507-13517 |
| Number of pages | 11 |
| Journal | Atmospheric Chemistry and Physics |
| Volume | 19 |
| Issue number | 21 |
| DOIs | |
| State | Published - 6 Nov 2019 |
| Externally published | Yes |
Bibliographical note
Funding Information:Financial support. This research has been supported by the Natural
Funding Information:
Acknowledgements. George Spill acknowledges funding from the Natural Environment Research Council with grant reference num- ber 1796357, and from the UK Met Office, and the use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. Guy Dagan and Philip Stier acknowledge funding from the European Research Council project RECAP under the European Union’s Horizon 2020 research and innovation programme with grant agreement no. 724602. Philip Stier additionally acknowledges funding from the Natural Environment Research Council project NE/L01355X/1 (CLARIFY) and from and NE/P013406/1 (A-CURE).
Funding Information:
Environment Research Council (grant no. 1796357), the Met Office Academic Partnership (grant no. 1796357), the Horizon 2020 (grant no. RECAP (724602)), and the Natural Environment Research Council (grant nos. NE/L01355X/1 and NE/P013406/1).
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