Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations
Cumulus entrainment is a complex process that has long challenged conceptual understanding and atmospheric prediction. To investigate this process observationally, two retrievals are used to generate multi-year climatologies of shallow-cumulus bulk entrainment ( ϵ ) at two Atmospheric Radiation Meas...
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ftosti:oai:osti.gov:1822325 2023-07-30T04:05:31+02:00 Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations Kirshbaum, Daniel J. Lamer, Katia 2022-05-18 application/pdf http://www.osti.gov/servlets/purl/1822325 https://www.osti.gov/biblio/1822325 https://doi.org/10.1175/jas-d-20-0377.1 unknown http://www.osti.gov/servlets/purl/1822325 https://www.osti.gov/biblio/1822325 https://doi.org/10.1175/jas-d-20-0377.1 doi:10.1175/jas-d-20-0377.1 54 ENVIRONMENTAL SCIENCES 2022 ftosti https://doi.org/10.1175/jas-d-20-0377.1 2023-07-11T10:07:16Z Cumulus entrainment is a complex process that has long challenged conceptual understanding and atmospheric prediction. To investigate this process observationally, two retrievals are used to generate multi-year climatologies of shallow-cumulus bulk entrainment ( ϵ ) at two Atmospheric Radiation Measurement cloud observatories, one in the US southern Great Plains (SGP) and the other in the Azores archipelago in the eastern North Atlantic (ENA). The statistical distributions of ϵ thus obtained, as well as certain environmental and cloud-related sensitivities of ϵ , are consistent with previous findings from large-eddy simulations. The retrieved ϵ robustly increases with cloudlayer relative humidity and decreases in wider clouds and cloud ensembles with larger cloud-base mass fluxes. While ϵ also correlates negatively with measures of cloud-layer vigor (e.g., maximum in-cloud vertical velocity and cloud depth), the extent to which these metrics actually regulate ϵ (or vice-versa) is unclear. Novel sensitivities of ϵ include a robust decrease of ϵ with increasing subcloud wind speed in oceanic flows, as well as a decrease of ϵ with increasing cloud-base mass flux in individual cumuli. A strong land–ocean contrast in ϵ is also found, with median values of 0.5-0.6 km -1 at the continental SGP site and and 1.0-1.1 km -1 at the oceanic ENA site. This trend is associated with drier and deeper cloud layers, along with larger cloud-base mass fluxes, at SGP, all of which favor reduced ϵ . The flow-dependence of retrieved ϵ implies that its various sensitivities should be accounted for in cumulus parameterization schemes. Other/Unknown Material North Atlantic SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Journal of the Atmospheric Sciences |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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ftosti |
language |
unknown |
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54 ENVIRONMENTAL SCIENCES |
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54 ENVIRONMENTAL SCIENCES Kirshbaum, Daniel J. Lamer, Katia Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations |
topic_facet |
54 ENVIRONMENTAL SCIENCES |
description |
Cumulus entrainment is a complex process that has long challenged conceptual understanding and atmospheric prediction. To investigate this process observationally, two retrievals are used to generate multi-year climatologies of shallow-cumulus bulk entrainment ( ϵ ) at two Atmospheric Radiation Measurement cloud observatories, one in the US southern Great Plains (SGP) and the other in the Azores archipelago in the eastern North Atlantic (ENA). The statistical distributions of ϵ thus obtained, as well as certain environmental and cloud-related sensitivities of ϵ , are consistent with previous findings from large-eddy simulations. The retrieved ϵ robustly increases with cloudlayer relative humidity and decreases in wider clouds and cloud ensembles with larger cloud-base mass fluxes. While ϵ also correlates negatively with measures of cloud-layer vigor (e.g., maximum in-cloud vertical velocity and cloud depth), the extent to which these metrics actually regulate ϵ (or vice-versa) is unclear. Novel sensitivities of ϵ include a robust decrease of ϵ with increasing subcloud wind speed in oceanic flows, as well as a decrease of ϵ with increasing cloud-base mass flux in individual cumuli. A strong land–ocean contrast in ϵ is also found, with median values of 0.5-0.6 km -1 at the continental SGP site and and 1.0-1.1 km -1 at the oceanic ENA site. This trend is associated with drier and deeper cloud layers, along with larger cloud-base mass fluxes, at SGP, all of which favor reduced ϵ . The flow-dependence of retrieved ϵ implies that its various sensitivities should be accounted for in cumulus parameterization schemes. |
author |
Kirshbaum, Daniel J. Lamer, Katia |
author_facet |
Kirshbaum, Daniel J. Lamer, Katia |
author_sort |
Kirshbaum, Daniel J. |
title |
Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations |
title_short |
Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations |
title_full |
Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations |
title_fullStr |
Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations |
title_full_unstemmed |
Climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations |
title_sort |
climatological sensitivities of shallow-cumulus bulk entrainment in continental and oceanic locations |
publishDate |
2022 |
url |
http://www.osti.gov/servlets/purl/1822325 https://www.osti.gov/biblio/1822325 https://doi.org/10.1175/jas-d-20-0377.1 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://www.osti.gov/servlets/purl/1822325 https://www.osti.gov/biblio/1822325 https://doi.org/10.1175/jas-d-20-0377.1 doi:10.1175/jas-d-20-0377.1 |
op_doi |
https://doi.org/10.1175/jas-d-20-0377.1 |
container_title |
Journal of the Atmospheric Sciences |
_version_ |
1772817495685595136 |