Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties
We compare turbulence properties in coupled and decoupled marine stratocumulus-topped boundary layers (STBLs) using high-resolution in situ measurements performed by the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) platform in the region of the eastern North Atlantic. The th...
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2021
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Online Access: | https://oa.tib.eu/renate/handle/123456789/8146 https://doi.org/10.34657/7186 |
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ftleibnizopen:oai:oai.leibnizopen.de:5-9q6YoBg80Wlv18x4LQ 2023-10-29T02:38:43+01:00 Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties Nowak, Jakub L. Siebert, Holger Szodry, Kai-Erik Malinowski, Szymon P. 2021 application/pdf https://oa.tib.eu/renate/handle/123456789/8146 https://doi.org/10.34657/7186 eng eng Katlenburg-Lindau : European Geosciences Union https://creativecommons.org/licenses/by/4.0/ Atmospheric Chemistry and Physics 21 (2021), Nr. 14 atmospheric convection boundary layer coupling energy dissipation humidity latent heat flux marine atmosphere stratocumulus thermodynamics turbulence Atlantic Ocean Atlantic Ocean (North) 550 article Text 2021 ftleibnizopen https://doi.org/10.34657/7186 2023-10-01T23:11:58Z We compare turbulence properties in coupled and decoupled marine stratocumulus-topped boundary layers (STBLs) using high-resolution in situ measurements performed by the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) platform in the region of the eastern North Atlantic. The thermodynamically well-mixed coupled STBL was characterized by a comparable latent heat flux at the surface and in the cloud-top region, and substantially smaller sensible heat flux in the entire depth. Turbulence kinetic energy (TKE) was efficiently generated by buoyancy in the cloud and at the surface, and dissipated with comparable rate across the entire depth. Structure functions and power spectra of velocity fluctuations in the inertial range were reasonably consistent with the predictions of Kolmogorov theory. The turbulence was close to isotropic. In the decoupled STBL, decoupling was most obvious in humidity profiles. Heat fluxes and buoyant TKE production at the surface were similar to the coupled case. Around the transition level, latent heat flux decreased to zero and TKE was consumed by weak stability. In the cloud-top region, heat fluxes almost vanished and buoyancy production was significantly smaller than for the coupled case. The TKE dissipation rate inside the decoupled STBL varied between its sublayers. Structure functions and power spectra in the inertial range deviated from Kolmogorov scaling. This was more pronounced in the cloud and subcloud layer in comparison to the surface mixed layer. The turbulence was more anisotropic than in the coupled STBL, with horizontal fluctuations dominating. The degree of anisotropy was largest in the cloud and subcloud layer of the decoupled STBL. Integral length scales, of the order of 100gm in both cases, indicate turbulent eddies smaller than the depth of the coupled STBL or of the sublayers of the decoupled STBL. We hypothesize that turbulence produced in the cloud or close to the surface is redistributed across the entire coupled STBL but rather only inside the ... Article in Journal/Newspaper North Atlantic LeibnizOpen (The Leibniz Association) |
institution |
Open Polar |
collection |
LeibnizOpen (The Leibniz Association) |
op_collection_id |
ftleibnizopen |
language |
English |
topic |
atmospheric convection boundary layer coupling energy dissipation humidity latent heat flux marine atmosphere stratocumulus thermodynamics turbulence Atlantic Ocean Atlantic Ocean (North) 550 |
spellingShingle |
atmospheric convection boundary layer coupling energy dissipation humidity latent heat flux marine atmosphere stratocumulus thermodynamics turbulence Atlantic Ocean Atlantic Ocean (North) 550 Nowak, Jakub L. Siebert, Holger Szodry, Kai-Erik Malinowski, Szymon P. Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties |
topic_facet |
atmospheric convection boundary layer coupling energy dissipation humidity latent heat flux marine atmosphere stratocumulus thermodynamics turbulence Atlantic Ocean Atlantic Ocean (North) 550 |
description |
We compare turbulence properties in coupled and decoupled marine stratocumulus-topped boundary layers (STBLs) using high-resolution in situ measurements performed by the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) platform in the region of the eastern North Atlantic. The thermodynamically well-mixed coupled STBL was characterized by a comparable latent heat flux at the surface and in the cloud-top region, and substantially smaller sensible heat flux in the entire depth. Turbulence kinetic energy (TKE) was efficiently generated by buoyancy in the cloud and at the surface, and dissipated with comparable rate across the entire depth. Structure functions and power spectra of velocity fluctuations in the inertial range were reasonably consistent with the predictions of Kolmogorov theory. The turbulence was close to isotropic. In the decoupled STBL, decoupling was most obvious in humidity profiles. Heat fluxes and buoyant TKE production at the surface were similar to the coupled case. Around the transition level, latent heat flux decreased to zero and TKE was consumed by weak stability. In the cloud-top region, heat fluxes almost vanished and buoyancy production was significantly smaller than for the coupled case. The TKE dissipation rate inside the decoupled STBL varied between its sublayers. Structure functions and power spectra in the inertial range deviated from Kolmogorov scaling. This was more pronounced in the cloud and subcloud layer in comparison to the surface mixed layer. The turbulence was more anisotropic than in the coupled STBL, with horizontal fluctuations dominating. The degree of anisotropy was largest in the cloud and subcloud layer of the decoupled STBL. Integral length scales, of the order of 100gm in both cases, indicate turbulent eddies smaller than the depth of the coupled STBL or of the sublayers of the decoupled STBL. We hypothesize that turbulence produced in the cloud or close to the surface is redistributed across the entire coupled STBL but rather only inside the ... |
format |
Article in Journal/Newspaper |
author |
Nowak, Jakub L. Siebert, Holger Szodry, Kai-Erik Malinowski, Szymon P. |
author_facet |
Nowak, Jakub L. Siebert, Holger Szodry, Kai-Erik Malinowski, Szymon P. |
author_sort |
Nowak, Jakub L. |
title |
Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties |
title_short |
Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties |
title_full |
Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties |
title_fullStr |
Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties |
title_full_unstemmed |
Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties |
title_sort |
coupled and decoupled stratocumulus-topped boundary layers: turbulence properties |
publisher |
Katlenburg-Lindau : European Geosciences Union |
publishDate |
2021 |
url |
https://oa.tib.eu/renate/handle/123456789/8146 https://doi.org/10.34657/7186 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Atmospheric Chemistry and Physics 21 (2021), Nr. 14 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.34657/7186 |
_version_ |
1781065027160113152 |