Sensitivity of Arctic Clouds to Ice Microphysical Processes in the NorESM2 Climate Model
(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.
(Less)
- author
- Sotiropoulou, Georgia
; Lewinschal, Anna
; Georgakaki, Paraskevi
; Phillips, Vaughan T.J.
LU
; Patade, Sachin LU ; Ekman, Annica M.L. and Nenes, Athanasios
- organization
- publishing date
- 2024-08
- 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
- 2024-09-05 15:18:18
@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}}, }