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Sensitivity of Arctic Clouds to Ice Microphysical Processes in the NorESM2 Climate Model

Sotiropoulou, Georgia ; Lewinschal, Anna ; Georgakaki, Paraskevi ; Phillips, Vaughan T.J. LU orcid ; Patade, Sachin LU ; Ekman, Annica M.L. and Nenes, Athanasios (2024) In Journal of Climate 37(16). p.4275-4290
Abstract

Ice formation remains one of the most poorly represented microphysical processes in climate models. While primary ice production (PIP) parameterizations are known to have a large influence on the modeled cloud properties, the representation of secondary ice production (SIP) is incomplete and its corresponding impact is therefore largely unquantified. Furthermore, ice aggregation is another important process for the total cloud ice budget, which also remains largely unconstrained. In this study, we examine the impact of PIP, SIP, and ice aggregation on Arctic clouds, using the Norwegian Earth System Model, version 2 (NorESM2). Simulations with both prognostic and diagnostic PIP show that heterogeneous freezing alone cannot reproduce the... (More)

Ice formation remains one of the most poorly represented microphysical processes in climate models. While primary ice production (PIP) parameterizations are known to have a large influence on the modeled cloud properties, the representation of secondary ice production (SIP) is incomplete and its corresponding impact is therefore largely unquantified. Furthermore, ice aggregation is another important process for the total cloud ice budget, which also remains largely unconstrained. In this study, we examine the impact of PIP, SIP, and ice aggregation on Arctic clouds, using the Norwegian Earth System Model, version 2 (NorESM2). Simulations with both prognostic and diagnostic PIP show that heterogeneous freezing alone cannot reproduce the observed cloud ice content. The implementation of missing SIP mechanisms (collisional breakup, drop shattering, and sublimation breakup) in NorESM2 improves the modeled ice properties, while improvements in liquid content occur only in simulations with prognostic PIP. However, results are sensitive to the description of collisional breakup. This mechanism, which dominates SIP in the examined conditions, is very sensitive to the treatment of the sublimation correction factor, a poorly constrained parameter that is included in the utilized parameterization. Finally, variations in ice aggregation treatment can also significantly impact cloud properties, mainly through their impact on collisional breakup efficiency. Overall, enhancement in ice production through the addition of SIP mechanisms and the reduction in ice aggregation (in line with radar observations of shallow Arctic clouds) result in enhanced cloud cover and decreased TOA radiation biases, compared to satellite measurements, especially during the cold months.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Arctic, Climate models, Cloud microphysics, Cloud parameterizations, Clouds, Secondary ice production
in
Journal of Climate
volume
37
issue
16
pages
16 pages
publisher
American Meteorological Society
external identifiers
  • scopus:85196163013
ISSN
0894-8755
DOI
10.1175/JCLI-D-22-0458.1
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2024 American Meteorological Society.
id
8323734d-701b-48d6-9160-96c17a8caa0e
date added to LUP
2024-09-04 18:25:58
date last changed
2025-04-04 14:34:03
@article{8323734d-701b-48d6-9160-96c17a8caa0e,
  abstract     = {{<p>Ice formation remains one of the most poorly represented microphysical processes in climate models. While primary ice production (PIP) parameterizations are known to have a large influence on the modeled cloud properties, the representation of secondary ice production (SIP) is incomplete and its corresponding impact is therefore largely unquantified. Furthermore, ice aggregation is another important process for the total cloud ice budget, which also remains largely unconstrained. In this study, we examine the impact of PIP, SIP, and ice aggregation on Arctic clouds, using the Norwegian Earth System Model, version 2 (NorESM2). Simulations with both prognostic and diagnostic PIP show that heterogeneous freezing alone cannot reproduce the observed cloud ice content. The implementation of missing SIP mechanisms (collisional breakup, drop shattering, and sublimation breakup) in NorESM2 improves the modeled ice properties, while improvements in liquid content occur only in simulations with prognostic PIP. However, results are sensitive to the description of collisional breakup. This mechanism, which dominates SIP in the examined conditions, is very sensitive to the treatment of the sublimation correction factor, a poorly constrained parameter that is included in the utilized parameterization. Finally, variations in ice aggregation treatment can also significantly impact cloud properties, mainly through their impact on collisional breakup efficiency. Overall, enhancement in ice production through the addition of SIP mechanisms and the reduction in ice aggregation (in line with radar observations of shallow Arctic clouds) result in enhanced cloud cover and decreased TOA radiation biases, compared to satellite measurements, especially during the cold months.</p>}},
  author       = {{Sotiropoulou, Georgia and Lewinschal, Anna and Georgakaki, Paraskevi and Phillips, Vaughan T.J. and Patade, Sachin and Ekman, Annica M.L. and Nenes, Athanasios}},
  issn         = {{0894-8755}},
  keywords     = {{Arctic; Climate models; Cloud microphysics; Cloud parameterizations; Clouds; Secondary ice production}},
  language     = {{eng}},
  number       = {{16}},
  pages        = {{4275--4290}},
  publisher    = {{American Meteorological Society}},
  series       = {{Journal of Climate}},
  title        = {{Sensitivity of Arctic Clouds to Ice Microphysical Processes in the NorESM2 Climate Model}},
  url          = {{http://dx.doi.org/10.1175/JCLI-D-22-0458.1}},
  doi          = {{10.1175/JCLI-D-22-0458.1}},
  volume       = {{37}},
  year         = {{2024}},
}