Local and Remote Controls on Arctic Mixed-Layer Evolution
In this study Lagrangian large-eddy simulation of cloudy mixed layers in evolving warm air masses in the Arctic is constrained by in situ observations from the recent PASCAL field campaign. A key novelty is that time dependence is maintained in the large-scale forcings. An iterative procedure featur...
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ftleibnizopen:oai:oai.leibnizopen.de:5of5pIkBdbrxVwz62cJ9 2023-08-20T04:03:50+02:00 Local and Remote Controls on Arctic Mixed-Layer Evolution Neggers, R.A.J. Chylik, J. Egerer, U. Griesche, H. Schemann, V. Seifert, P. Siebert, H. Macke, A. 2020 application/pdf https://oa.tib.eu/renate/handle/123456789/7274 https://doi.org/10.34657/6321 eng eng Malden MA: Wiley-Blackwell CC BY-NC-ND 4.0 Unported https://creativecommons.org/licenses/by-nc-nd/4.0/ Journal of advances in modeling earth systems : JAMES 11 (2020), Nr. 7 Arctic mixed layers Arctic mixed-phase clouds large-eddy simulation large-scale subsidence Polarstern research Vessel warm air intrusions 550 article Text 2020 ftleibnizopen https://doi.org/10.34657/6321 2023-07-30T23:11:02Z In this study Lagrangian large-eddy simulation of cloudy mixed layers in evolving warm air masses in the Arctic is constrained by in situ observations from the recent PASCAL field campaign. A key novelty is that time dependence is maintained in the large-scale forcings. An iterative procedure featuring large-eddy simulation on microgrids is explored to calibrate the case setup, inspired by and making use of the typically long memory of Arctic air masses for upstream conditions. The simulated mixed-phase clouds are part of a turbulent mixed layer that is weakly coupled to the surface and is occasionally capped by a shallow humidity layer. All eight simulated mixed layers exhibit a strong time evolution across a range of time scales, including diurnal but also synoptic fingerprints. A few cases experience rapid cloud collapse, coinciding with a rapid decrease in mixed-layer depth. To gain insight, composite budget analyses are performed. In the mixed-layer interior the heat and moisture budgets are dominated by turbulent transport, radiative cooling, and precipitation. However, near the thermal inversion the large-scale vertical advection also contributes significantly, showing a distinct difference between subsidence and upsidence conditions. A bulk mass budget analysis reveals that entrainment deepening behaves almost time-constantly, as long as clouds are present. In contrast, large-scale subsidence fluctuates much more strongly and can both counteract and boost boundary-layer deepening resulting from entrainment. Strong and sudden subsidence events following prolonged deepening periods are found to cause the cloud collapses, associated with a substantial reduction in the surface downward longwave radiative flux. ©2019. The Authors. publishedVersion Article in Journal/Newspaper Arctic LeibnizOpen (The Leibniz Association) Arctic |
institution |
Open Polar |
collection |
LeibnizOpen (The Leibniz Association) |
op_collection_id |
ftleibnizopen |
language |
English |
topic |
Arctic mixed layers Arctic mixed-phase clouds large-eddy simulation large-scale subsidence Polarstern research Vessel warm air intrusions 550 |
spellingShingle |
Arctic mixed layers Arctic mixed-phase clouds large-eddy simulation large-scale subsidence Polarstern research Vessel warm air intrusions 550 Neggers, R.A.J. Chylik, J. Egerer, U. Griesche, H. Schemann, V. Seifert, P. Siebert, H. Macke, A. Local and Remote Controls on Arctic Mixed-Layer Evolution |
topic_facet |
Arctic mixed layers Arctic mixed-phase clouds large-eddy simulation large-scale subsidence Polarstern research Vessel warm air intrusions 550 |
description |
In this study Lagrangian large-eddy simulation of cloudy mixed layers in evolving warm air masses in the Arctic is constrained by in situ observations from the recent PASCAL field campaign. A key novelty is that time dependence is maintained in the large-scale forcings. An iterative procedure featuring large-eddy simulation on microgrids is explored to calibrate the case setup, inspired by and making use of the typically long memory of Arctic air masses for upstream conditions. The simulated mixed-phase clouds are part of a turbulent mixed layer that is weakly coupled to the surface and is occasionally capped by a shallow humidity layer. All eight simulated mixed layers exhibit a strong time evolution across a range of time scales, including diurnal but also synoptic fingerprints. A few cases experience rapid cloud collapse, coinciding with a rapid decrease in mixed-layer depth. To gain insight, composite budget analyses are performed. In the mixed-layer interior the heat and moisture budgets are dominated by turbulent transport, radiative cooling, and precipitation. However, near the thermal inversion the large-scale vertical advection also contributes significantly, showing a distinct difference between subsidence and upsidence conditions. A bulk mass budget analysis reveals that entrainment deepening behaves almost time-constantly, as long as clouds are present. In contrast, large-scale subsidence fluctuates much more strongly and can both counteract and boost boundary-layer deepening resulting from entrainment. Strong and sudden subsidence events following prolonged deepening periods are found to cause the cloud collapses, associated with a substantial reduction in the surface downward longwave radiative flux. ©2019. The Authors. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Neggers, R.A.J. Chylik, J. Egerer, U. Griesche, H. Schemann, V. Seifert, P. Siebert, H. Macke, A. |
author_facet |
Neggers, R.A.J. Chylik, J. Egerer, U. Griesche, H. Schemann, V. Seifert, P. Siebert, H. Macke, A. |
author_sort |
Neggers, R.A.J. |
title |
Local and Remote Controls on Arctic Mixed-Layer Evolution |
title_short |
Local and Remote Controls on Arctic Mixed-Layer Evolution |
title_full |
Local and Remote Controls on Arctic Mixed-Layer Evolution |
title_fullStr |
Local and Remote Controls on Arctic Mixed-Layer Evolution |
title_full_unstemmed |
Local and Remote Controls on Arctic Mixed-Layer Evolution |
title_sort |
local and remote controls on arctic mixed-layer evolution |
publisher |
Malden MA: Wiley-Blackwell |
publishDate |
2020 |
url |
https://oa.tib.eu/renate/handle/123456789/7274 https://doi.org/10.34657/6321 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Journal of advances in modeling earth systems : JAMES 11 (2020), Nr. 7 |
op_rights |
CC BY-NC-ND 4.0 Unported https://creativecommons.org/licenses/by-nc-nd/4.0/ |
op_doi |
https://doi.org/10.34657/6321 |
_version_ |
1774714266133200896 |