In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic
<p>A key challenge for numerical weather prediction models is representing boundary layer clouds in cold air outbreaks (CAOs). One important aspect is the evolution of microphysical properties as stratocumulus transitions to open cellular convection. Abel et al. (2017) have shown, for the firs...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-12-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/17191/2018/acp-18-17191-2018.pdf |
| _version_ | 1818601082743422976 |
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| author | G. Lloyd G. Lloyd T. W. Choularton K. N. Bower M. W. Gallagher J. Crosier J. Crosier S. O'Shea S. J. Abel S. Fox R. Cotton I. A. Boutle |
| author_facet | G. Lloyd G. Lloyd T. W. Choularton K. N. Bower M. W. Gallagher J. Crosier J. Crosier S. O'Shea S. J. Abel S. Fox R. Cotton I. A. Boutle |
| author_sort | G. Lloyd |
| collection | DOAJ |
| description | <p>A key challenge for numerical weather prediction
models is representing boundary layer clouds in cold air outbreaks (CAOs).
One important aspect is the evolution of microphysical properties as
stratocumulus transitions to open cellular convection. Abel et al. (2017)
have shown, for the first time from in situ field observations, that the
break-up in CAOs over the eastern Atlantic may be controlled by the
development of precipitation in the cloud system while the boundary layer
becomes decoupled. This paper describes that case and examines in situ
measurements from three more CAOs. Flights were conducted using the UK
Facility for Airborne Atmospheric Measurements (FAAM) British Aerospace-146
(BAe-146) aircraft in the North Atlantic region around the UK, making
detailed microphysical measurements in the stratiform boundary layer. As the
cloudy boundary layer evolves prior to break-up, increasing liquid water
paths (LWPs) and drop sizes and the formation of liquid precipitation are
observed. Small numbers of ice particles, typically a few per litre, are also
observed. Eventually LWPs reduce significantly due to loss of water from the
stratocumulus cloud (SC) layer. In three of the cases, aerosols are removed
from the boundary layer across the transition. This process appears to be
similar to those observed in warm clouds and pockets of open cells (POCs) in
the subtropics. After break-up, deeper convective clouds form with bases warm
enough for secondary ice production (SIP), leading to rapid glaciation. It is
concluded that the precipitation is strongly associated with the break-up,
with both weakening of the capping inversion and boundary layer decoupling
also observed.</p> |
| first_indexed | 2024-12-16T12:45:44Z |
| format | Article |
| id | doaj.art-b8697e938005430a9bbc69c3ad894106 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-16T12:45:44Z |
| publishDate | 2018-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-b8697e938005430a9bbc69c3ad8941062022-12-21T22:31:17ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242018-12-0118171911720610.5194/acp-18-17191-2018In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North AtlanticG. Lloyd0G. Lloyd1T. W. Choularton2K. N. Bower3M. W. Gallagher4J. Crosier5J. Crosier6S. O'Shea7S. J. Abel8S. Fox9R. Cotton10I. A. Boutle11NERC National Centre for Atmospheric Science (NCAS), Leeds, UKCentre for Atmospheric Science, University of Manchester, Manchester, UKCentre for Atmospheric Science, University of Manchester, Manchester, UKCentre for Atmospheric Science, University of Manchester, Manchester, UKCentre for Atmospheric Science, University of Manchester, Manchester, UKNERC National Centre for Atmospheric Science (NCAS), Leeds, UKCentre for Atmospheric Science, University of Manchester, Manchester, UKNERC National Centre for Atmospheric Science (NCAS), Leeds, UKMet Office, Exeter, UKMet Office, Exeter, UKMet Office, Exeter, UKMet Office, Exeter, UK<p>A key challenge for numerical weather prediction models is representing boundary layer clouds in cold air outbreaks (CAOs). One important aspect is the evolution of microphysical properties as stratocumulus transitions to open cellular convection. Abel et al. (2017) have shown, for the first time from in situ field observations, that the break-up in CAOs over the eastern Atlantic may be controlled by the development of precipitation in the cloud system while the boundary layer becomes decoupled. This paper describes that case and examines in situ measurements from three more CAOs. Flights were conducted using the UK Facility for Airborne Atmospheric Measurements (FAAM) British Aerospace-146 (BAe-146) aircraft in the North Atlantic region around the UK, making detailed microphysical measurements in the stratiform boundary layer. As the cloudy boundary layer evolves prior to break-up, increasing liquid water paths (LWPs) and drop sizes and the formation of liquid precipitation are observed. Small numbers of ice particles, typically a few per litre, are also observed. Eventually LWPs reduce significantly due to loss of water from the stratocumulus cloud (SC) layer. In three of the cases, aerosols are removed from the boundary layer across the transition. This process appears to be similar to those observed in warm clouds and pockets of open cells (POCs) in the subtropics. After break-up, deeper convective clouds form with bases warm enough for secondary ice production (SIP), leading to rapid glaciation. It is concluded that the precipitation is strongly associated with the break-up, with both weakening of the capping inversion and boundary layer decoupling also observed.</p>https://www.atmos-chem-phys.net/18/17191/2018/acp-18-17191-2018.pdf |
| spellingShingle | G. Lloyd G. Lloyd T. W. Choularton K. N. Bower M. W. Gallagher J. Crosier J. Crosier S. O'Shea S. J. Abel S. Fox R. Cotton I. A. Boutle In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic Atmospheric Chemistry and Physics |
| title | In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic |
| title_full | In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic |
| title_fullStr | In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic |
| title_full_unstemmed | In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic |
| title_short | In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic |
| title_sort | in situ measurements of cloud microphysical and aerosol properties during the break up of stratocumulus cloud layers in cold air outbreaks over the north atlantic |
| url | https://www.atmos-chem-phys.net/18/17191/2018/acp-18-17191-2018.pdf |
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