Sotiropoulou, G, Sedlar, J, Tjernström, M et al. (3 more authors) (2014) The thermodynamic structure of summer Arctic stratocumulus and the dynamic coupling to the surface. Atmospheric Chemistry and Physics, 14 (22). 12573 - 12592. ISSN 1680-7316
Abstract
The vertical structure of Arctic low-level clouds and Arctic boundary layer is studied, using observations from ASCOS (Arctic Summer Cloud Ocean Study), in the central Arctic, in late summer 2008. Two general types of cloud structures are examined: the "neutrally stratified" and "stably stratified" clouds. Neutrally stratified are mixed-phase clouds where radiative-cooling near cloud top produces turbulence that generates a cloud-driven mixed layer. When this layer mixes with the surface-generated turbulence, the cloud layer is coupled to the surface, whereas when such an interaction does not occur, it remains decoupled; the latter state is most frequently observed. The decoupled clouds are usually higher compared to the coupled; differences in thickness or cloud water properties between the two cases are however not found. The surface fluxes are also very similar for both states. The decoupled clouds exhibit a bimodal thermodynamic structure, depending on the depth of the sub-cloud mixed layer (SCML): clouds with shallower SCMLs are disconnected from the surface by weak inversions, whereas those that lay over a deeper SCML are associated with stronger inversions at the decoupling height. Neutrally stratified clouds generally precipitate; the evaporation/sublimation of precipitation often enhances the decoupling state. Finally, stably stratified clouds are usually lower, geometrically and optically thinner, non-precipitating liquid-water clouds, not containing enough liquid to drive efficient mixing through cloud-top cooling.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 19 Jan 2015 10:27 |
Last Modified: | 19 Jan 2015 10:27 |
Published Version: | http://dx.doi.org/10.5194/acp-14-12573-2014 |
Status: | Published |
Publisher: | Copernicus GmbH |
Refereed: | Yes |
Identification Number: | 10.5194/acp-14-12573-2014 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:82563 |