Characterization of oceanic post-cold frontal clouds and their model representation. Final report
Low-level clouds are ubiquitous over the oceans, and their impact on the Earth’ radiative budget is important. However, general circulation models (GCMs) that are used to represent our climate and its evolution still experience problems to represent their correct amount and radiative impact. In the...
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ftosti:oai:osti.gov:1616155 2023-07-30T04:05:39+02:00 Characterization of oceanic post-cold frontal clouds and their model representation. Final report Naud, Catherine Booth, James Gettelman, Andrew 2021-11-10 application/pdf http://www.osti.gov/servlets/purl/1616155 https://www.osti.gov/biblio/1616155 https://doi.org/10.2172/1616155 unknown http://www.osti.gov/servlets/purl/1616155 https://www.osti.gov/biblio/1616155 https://doi.org/10.2172/1616155 doi:10.2172/1616155 58 GEOSCIENCES 54 ENVIRONMENTAL SCIENCES 2021 ftosti https://doi.org/10.2172/1616155 2023-07-11T09:41:41Z Low-level clouds are ubiquitous over the oceans, and their impact on the Earth’ radiative budget is important. However, general circulation models (GCMs) that are used to represent our climate and its evolution still experience problems to represent their correct amount and radiative impact. In the extratropical latitudes (~30-60 N/S), cloud properties are strongly modulated by the occurrence of anti-cyclones (high pressure systems) and cyclones (low pressure systems). While deep clouds dominate in cyclones near the center and along the cold and warm fronts, low-level clouds populate the colder regions of the cyclones, and more specifically the region in the wake of the cold fronts, the post-cold frontal region (PCF). The GCMs mentioned above were found to underestimate the amount of these PCF clouds, and this caused errors in their representation of the amount of solar radiation at the surface of the southern hemisphere oceans, causing an excess in absorption and errors in long-term predictions. To better understand which processes are ill-represented in the GCMs to cause such issues, we used ground-based observations from the Eastern North Atlantic (ENA) ARM site and a high resolution regional model (called WRF) to examine the properties of PCF clouds. With the WRF model, we simulated the passage of a cold front at the ENA site using theoretically distinct representations of convection and the physics of the boundary layer. While these physical representations had little impact on the timing, structure and circulation of the cold front, we found a high sensitivity to how the large scale information was fed into the model. Errors rapidly developed if the incoming flow information was injected too far from the site, but 1000 km was found to be an optimal distance between the outer boundary and the ENA site for a realistic cold front passage. With this model, we then conducted a series of experiment where convection and boundary layer schemes were changed, and revealed that 1) the clouds were more sensitive to ... Other/Unknown Material North Atlantic SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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58 GEOSCIENCES 54 ENVIRONMENTAL SCIENCES |
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58 GEOSCIENCES 54 ENVIRONMENTAL SCIENCES Naud, Catherine Booth, James Gettelman, Andrew Characterization of oceanic post-cold frontal clouds and their model representation. Final report |
topic_facet |
58 GEOSCIENCES 54 ENVIRONMENTAL SCIENCES |
description |
Low-level clouds are ubiquitous over the oceans, and their impact on the Earth’ radiative budget is important. However, general circulation models (GCMs) that are used to represent our climate and its evolution still experience problems to represent their correct amount and radiative impact. In the extratropical latitudes (~30-60 N/S), cloud properties are strongly modulated by the occurrence of anti-cyclones (high pressure systems) and cyclones (low pressure systems). While deep clouds dominate in cyclones near the center and along the cold and warm fronts, low-level clouds populate the colder regions of the cyclones, and more specifically the region in the wake of the cold fronts, the post-cold frontal region (PCF). The GCMs mentioned above were found to underestimate the amount of these PCF clouds, and this caused errors in their representation of the amount of solar radiation at the surface of the southern hemisphere oceans, causing an excess in absorption and errors in long-term predictions. To better understand which processes are ill-represented in the GCMs to cause such issues, we used ground-based observations from the Eastern North Atlantic (ENA) ARM site and a high resolution regional model (called WRF) to examine the properties of PCF clouds. With the WRF model, we simulated the passage of a cold front at the ENA site using theoretically distinct representations of convection and the physics of the boundary layer. While these physical representations had little impact on the timing, structure and circulation of the cold front, we found a high sensitivity to how the large scale information was fed into the model. Errors rapidly developed if the incoming flow information was injected too far from the site, but 1000 km was found to be an optimal distance between the outer boundary and the ENA site for a realistic cold front passage. With this model, we then conducted a series of experiment where convection and boundary layer schemes were changed, and revealed that 1) the clouds were more sensitive to ... |
author |
Naud, Catherine Booth, James Gettelman, Andrew |
author_facet |
Naud, Catherine Booth, James Gettelman, Andrew |
author_sort |
Naud, Catherine |
title |
Characterization of oceanic post-cold frontal clouds and their model representation. Final report |
title_short |
Characterization of oceanic post-cold frontal clouds and their model representation. Final report |
title_full |
Characterization of oceanic post-cold frontal clouds and their model representation. Final report |
title_fullStr |
Characterization of oceanic post-cold frontal clouds and their model representation. Final report |
title_full_unstemmed |
Characterization of oceanic post-cold frontal clouds and their model representation. Final report |
title_sort |
characterization of oceanic post-cold frontal clouds and their model representation. final report |
publishDate |
2021 |
url |
http://www.osti.gov/servlets/purl/1616155 https://www.osti.gov/biblio/1616155 https://doi.org/10.2172/1616155 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://www.osti.gov/servlets/purl/1616155 https://www.osti.gov/biblio/1616155 https://doi.org/10.2172/1616155 doi:10.2172/1616155 |
op_doi |
https://doi.org/10.2172/1616155 |
_version_ |
1772817727100026880 |