Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect

Over the last 1.5 years a CALIPSO satellite retrieval for cirrus clouds has been developed for number concentration Ni, effective diameter De and ice water content IWC. In general, these retrieved properties agree favorably with corresponding aircraft measurements from Krämer et al. (2020, ACP), but...

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Main Authors: Mitchell, D., Garnier, A.
Format: Conference Object
Language:English
Published: 2023
Subjects:
Online Access:https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016468
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spelling ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_5016468 2023-08-20T04:04:49+02:00 Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect Mitchell, D. Garnier, A. 2023 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016468 eng eng info:eu-repo/semantics/altIdentifier/doi/10.57757/IUGG23-1000 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016468 XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) info:eu-repo/semantics/conferenceObject 2023 ftgfzpotsdam https://doi.org/10.57757/IUGG23-1000 2023-07-30T23:40:44Z Over the last 1.5 years a CALIPSO satellite retrieval for cirrus clouds has been developed for number concentration Ni, effective diameter De and ice water content IWC. In general, these retrieved properties agree favorably with corresponding aircraft measurements from Krämer et al. (2020, ACP), but also show evidence that cirrus clouds form in two ways; (1) primarily through heterogeneous ice nucleation (het) only (henceforth het cirrus) and (2) through het and homogeneous ice nucleation (hom) combined (henceforth hom cirrus). Het cirrus represent 55% to 80% of all sampled cirrus (depending on 30° latitude band and appear to be most sampled during field campaigns) and have visible extinction coefficients αext < 0.3 km-1. Hom cirrus have αext > 0.3 km-1, and outside the tropics, are responsible for 72% to 81% of the estimated net cloud radiative effect for all cirrus clouds (depending on latitude band). They are often associated with warm fronts and orographic gravity waves. Using a simple model based on hom theory, the model-predicted Ni, De, and IWC are found to agree well with CALIPSO retrievals of these cloud properties that, based on retrieved Ni, correspond to hom, thus corroborating the role of hom. These results indicate that the climate intervention method known as cirrus cloud thinning (CCT) could be effective during Polar Night (i.e., winter, when Arctic Amplification is strongest). Moreover, hom cirrus in climate models may be underestimated due to the uniform treatment of pre-existing ice over prescribed atmospheric layers (i.e., ice nucleation is near cloud top). Conference Object Arctic polar night GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Arctic
institution Open Polar
collection GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam)
op_collection_id ftgfzpotsdam
language English
description Over the last 1.5 years a CALIPSO satellite retrieval for cirrus clouds has been developed for number concentration Ni, effective diameter De and ice water content IWC. In general, these retrieved properties agree favorably with corresponding aircraft measurements from Krämer et al. (2020, ACP), but also show evidence that cirrus clouds form in two ways; (1) primarily through heterogeneous ice nucleation (het) only (henceforth het cirrus) and (2) through het and homogeneous ice nucleation (hom) combined (henceforth hom cirrus). Het cirrus represent 55% to 80% of all sampled cirrus (depending on 30° latitude band and appear to be most sampled during field campaigns) and have visible extinction coefficients αext < 0.3 km-1. Hom cirrus have αext > 0.3 km-1, and outside the tropics, are responsible for 72% to 81% of the estimated net cloud radiative effect for all cirrus clouds (depending on latitude band). They are often associated with warm fronts and orographic gravity waves. Using a simple model based on hom theory, the model-predicted Ni, De, and IWC are found to agree well with CALIPSO retrievals of these cloud properties that, based on retrieved Ni, correspond to hom, thus corroborating the role of hom. These results indicate that the climate intervention method known as cirrus cloud thinning (CCT) could be effective during Polar Night (i.e., winter, when Arctic Amplification is strongest). Moreover, hom cirrus in climate models may be underestimated due to the uniform treatment of pre-existing ice over prescribed atmospheric layers (i.e., ice nucleation is near cloud top).
format Conference Object
author Mitchell, D.
Garnier, A.
spellingShingle Mitchell, D.
Garnier, A.
Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
author_facet Mitchell, D.
Garnier, A.
author_sort Mitchell, D.
title Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
title_short Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
title_full Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
title_fullStr Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
title_full_unstemmed Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
title_sort characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
publishDate 2023
url https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016468
geographic Arctic
geographic_facet Arctic
genre Arctic
polar night
genre_facet Arctic
polar night
op_source XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
op_relation info:eu-repo/semantics/altIdentifier/doi/10.57757/IUGG23-1000
https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016468
op_doi https://doi.org/10.57757/IUGG23-1000
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