A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution
The Arctic is currently warming faster than other regions of the Earth. Many processes and feedbacks contribute to the enhanced warming. Among these are the radiative effects of clouds. Arctic mixed-phase clouds, which contain both liquid and ice condensate, have high longevity and can exert signifi...
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Stockholms universitet, Meteorologiska institutionen (MISU)
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ftstockholmuniv:oai:DiVA.org:su-208653 2023-05-15T14:44:29+02:00 A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution Dimitrelos, Antonios 2022 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-208653 eng eng Stockholms universitet, Meteorologiska institutionen (MISU) Stockholm : Department of Meteorology, Stockholm University orcid:0000-0002-6139-0474 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-208653 urn:isbn:978-91-7911-996-6 urn:isbn:978-91-7911-997-3 info:eu-repo/semantics/openAccess Arctic mixed phase clouds sea ice Arctic amplification atmospheric energy transport CCN Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning Climate Research Klimatforskning Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2022 ftstockholmuniv 2023-02-23T21:44:11Z The Arctic is currently warming faster than other regions of the Earth. Many processes and feedbacks contribute to the enhanced warming. Among these are the radiative effects of clouds. Arctic mixed-phase clouds, which contain both liquid and ice condensate, have high longevity and can exert significant surface warming since the amount of solar radiation in the region is relatively low and the surface reflectivity often is high. In this thesis, we study these clouds utilizing a large-eddy model coupled with one-dimensional thermodynamic sea ice model. The main aim is to understand the interactions between cloud dynamics, microphysics, radiation, and turbulent processes and how these together govern the life cycle and surface warming of the clouds. By comparing a group of models with observations from the summertime high Arctic, we confirm the hypothesis that when aerosol concentrations are low, a small increase in their number concentration can increase the liquid water content of the cloud and in turn, the surface warming. Idealized simulations of moist intrusions into the Arctic show that the surface temperature may increase by more than 15o C if we allow clouds to form during a moist intrusion compared to if the atmosphere is cloud free. The simulations also show that the large-scale divergence rate strongly impacts the maintenance of the liquid layer at the top of these clouds. A main finding of the thesis is that the temperature of the cloud that forms during a moist intrusion is close to the initial dew point temperature. Thus, the surface warming induced by the clouds depends mostly on the initial humidity of the air mass rather than the initial temperature. In addition, the stability of the initial dew point temperature profile largely controls the turbulent state of the cloud. If the profile is unstable, then the cloud can transform from a thin, stable stratus to a deeper stratocumulus cloud, which also enhances the surface warming. Consequently, both the initial amount and the vertical structure of the ... Doctoral or Postdoctoral Thesis Arctic Sea ice Stockholm University: Publications (DiVA) Arctic |
institution |
Open Polar |
collection |
Stockholm University: Publications (DiVA) |
op_collection_id |
ftstockholmuniv |
language |
English |
topic |
Arctic mixed phase clouds sea ice Arctic amplification atmospheric energy transport CCN Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning Climate Research Klimatforskning |
spellingShingle |
Arctic mixed phase clouds sea ice Arctic amplification atmospheric energy transport CCN Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning Climate Research Klimatforskning Dimitrelos, Antonios A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution |
topic_facet |
Arctic mixed phase clouds sea ice Arctic amplification atmospheric energy transport CCN Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning Climate Research Klimatforskning |
description |
The Arctic is currently warming faster than other regions of the Earth. Many processes and feedbacks contribute to the enhanced warming. Among these are the radiative effects of clouds. Arctic mixed-phase clouds, which contain both liquid and ice condensate, have high longevity and can exert significant surface warming since the amount of solar radiation in the region is relatively low and the surface reflectivity often is high. In this thesis, we study these clouds utilizing a large-eddy model coupled with one-dimensional thermodynamic sea ice model. The main aim is to understand the interactions between cloud dynamics, microphysics, radiation, and turbulent processes and how these together govern the life cycle and surface warming of the clouds. By comparing a group of models with observations from the summertime high Arctic, we confirm the hypothesis that when aerosol concentrations are low, a small increase in their number concentration can increase the liquid water content of the cloud and in turn, the surface warming. Idealized simulations of moist intrusions into the Arctic show that the surface temperature may increase by more than 15o C if we allow clouds to form during a moist intrusion compared to if the atmosphere is cloud free. The simulations also show that the large-scale divergence rate strongly impacts the maintenance of the liquid layer at the top of these clouds. A main finding of the thesis is that the temperature of the cloud that forms during a moist intrusion is close to the initial dew point temperature. Thus, the surface warming induced by the clouds depends mostly on the initial humidity of the air mass rather than the initial temperature. In addition, the stability of the initial dew point temperature profile largely controls the turbulent state of the cloud. If the profile is unstable, then the cloud can transform from a thin, stable stratus to a deeper stratocumulus cloud, which also enhances the surface warming. Consequently, both the initial amount and the vertical structure of the ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Dimitrelos, Antonios |
author_facet |
Dimitrelos, Antonios |
author_sort |
Dimitrelos, Antonios |
title |
A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution |
title_short |
A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution |
title_full |
A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution |
title_fullStr |
A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution |
title_full_unstemmed |
A large-eddy simulation perspective on Arctic airmass transformation and low-level cloud evolution |
title_sort |
large-eddy simulation perspective on arctic airmass transformation and low-level cloud evolution |
publisher |
Stockholms universitet, Meteorologiska institutionen (MISU) |
publishDate |
2022 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-208653 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Sea ice |
genre_facet |
Arctic Sea ice |
op_relation |
orcid:0000-0002-6139-0474 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-208653 urn:isbn:978-91-7911-996-6 urn:isbn:978-91-7911-997-3 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766315967602753536 |