Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions
The cloud particle size distribution (PSD) is a key parameter for the retrieval of microphysical and optical properties from remote-sensing instruments, which in turn are necessary for determining the radiative effect of clouds. Current representations of PSDs for ice clouds rely on parameterization...
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ftunivlilleoa:oai:lilloa.univ-lille.fr:20.500.12210/114155 2024-06-23T07:50:43+00:00 Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions García, Irene Bartolomé Sourdeval, Odran Spang, Reinhold Krämer, Martina Université de Lille CNRS Institut für Energie- und Klimaforschung - Stratosphäre IEK-7 Laboratoire d'Optique Atmosphérique (LOA) - UMR 8518 Institute for Atmospheric Physics Mainz IPA 2024-05-29T08:04:16Z application/octet-stream application/rdf+xml; charset=utf-8 application/pdf https://hdl.handle.net/20.500.12210/114155 Anglais eng 10.5194/acp-24-1699-2024 Atmos. Chem. Phys. http://hdl.handle.net/20.500.12210/114155 Attribution 3.0 United States info:eu-repo/semantics/openAccess Article original 2024 ftunivlilleoa https://doi.org/20.500.12210/114155 2024-06-10T14:30:36Z The cloud particle size distribution (PSD) is a key parameter for the retrieval of microphysical and optical properties from remote-sensing instruments, which in turn are necessary for determining the radiative effect of clouds. Current representations of PSDs for ice clouds rely on parameterizations that were largely based on aircraft in situ measurements where the distribution of small ice crystals were uncertain. This makes current parameterizations deficient to simulate remote-sensing observations sensitive to small ice, such as from lidar and thermal infrared instruments. In this study we fit the in situ PSDs of ice crystals from the JULIA (JÜLich In situ Aircraft data set) database, which consists of 11 campaigns covering the tropics, midlatitudes and the Arctic, consistently processed and considered more robust in their measurements of small ice. For the fitting, we implement an established approach to PSD parameterizations, which consists of finding an adequate set of parameters for a modified gamma function after normalization of both PSD axes. These parameters are constrained to match in situ measurements when predicting microphysical properties from the PSDs, via a cost function minimization method. We selected the ice water content and the ice crystal number concentration, which are currently key parameters for modern satellite retrievals and model microphysics schemes. We found that a bimodal parameterization yields better results than a monomodal one. The bimodal parameterization has a lower spread for almost all ice crystal sizes over the entire range of analyzed temperatures and fits better the observations, especially for particles between 20 and about 110 µm at temperatures between −60 and −20 ∘C. For this temperature range, the root mean square error for the retrieved Nice is reduced from 0.36 to 0.20. This demonstrates a clear advantage to considering the bimodality of PSDs, e.g., for satellite retrievals. 24; Article in Journal/Newspaper Arctic LillOA (Lille Open Archive - Université de Lille) Arctic |
institution |
Open Polar |
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LillOA (Lille Open Archive - Université de Lille) |
op_collection_id |
ftunivlilleoa |
language |
English |
description |
The cloud particle size distribution (PSD) is a key parameter for the retrieval of microphysical and optical properties from remote-sensing instruments, which in turn are necessary for determining the radiative effect of clouds. Current representations of PSDs for ice clouds rely on parameterizations that were largely based on aircraft in situ measurements where the distribution of small ice crystals were uncertain. This makes current parameterizations deficient to simulate remote-sensing observations sensitive to small ice, such as from lidar and thermal infrared instruments. In this study we fit the in situ PSDs of ice crystals from the JULIA (JÜLich In situ Aircraft data set) database, which consists of 11 campaigns covering the tropics, midlatitudes and the Arctic, consistently processed and considered more robust in their measurements of small ice. For the fitting, we implement an established approach to PSD parameterizations, which consists of finding an adequate set of parameters for a modified gamma function after normalization of both PSD axes. These parameters are constrained to match in situ measurements when predicting microphysical properties from the PSDs, via a cost function minimization method. We selected the ice water content and the ice crystal number concentration, which are currently key parameters for modern satellite retrievals and model microphysics schemes. We found that a bimodal parameterization yields better results than a monomodal one. The bimodal parameterization has a lower spread for almost all ice crystal sizes over the entire range of analyzed temperatures and fits better the observations, especially for particles between 20 and about 110 µm at temperatures between −60 and −20 ∘C. For this temperature range, the root mean square error for the retrieved Nice is reduced from 0.36 to 0.20. This demonstrates a clear advantage to considering the bimodality of PSDs, e.g., for satellite retrievals. 24; |
author2 |
Université de Lille CNRS Institut für Energie- und Klimaforschung - Stratosphäre IEK-7 Laboratoire d'Optique Atmosphérique (LOA) - UMR 8518 Institute for Atmospheric Physics Mainz IPA |
format |
Article in Journal/Newspaper |
author |
García, Irene Bartolomé Sourdeval, Odran Spang, Reinhold Krämer, Martina |
spellingShingle |
García, Irene Bartolomé Sourdeval, Odran Spang, Reinhold Krämer, Martina Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions |
author_facet |
García, Irene Bartolomé Sourdeval, Odran Spang, Reinhold Krämer, Martina |
author_sort |
García, Irene Bartolomé |
title |
Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions |
title_short |
Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions |
title_full |
Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions |
title_fullStr |
Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions |
title_full_unstemmed |
Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions |
title_sort |
technical note: bimodal parameterizations of in situ ice cloud particle size distributions |
publishDate |
2024 |
url |
https://hdl.handle.net/20.500.12210/114155 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_relation |
10.5194/acp-24-1699-2024 Atmos. Chem. Phys. http://hdl.handle.net/20.500.12210/114155 |
op_rights |
Attribution 3.0 United States info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/20.500.12210/114155 |
_version_ |
1802641631315230720 |