Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics
Bubbles formed by breaking waves in the open ocean influence many surface processes but are poorly understood. We report here on detailed bubble size distributions measured during the High Wind Speed Gas Exchange Study (HiWinGS) in the North Atlantic, during four separate storms with hourly averaged...
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ftdoajarticles:oai:doaj.org/article:12b1e75186d7459ab9f606506f4ffb75 2023-05-15T17:36:44+02:00 Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics H. Czerski I. M. Brooks S. Gunn R. Pascal A. Matei B. Blomquist 2022-05-01T00:00:00Z https://doi.org/10.5194/os-18-587-2022 https://doaj.org/article/12b1e75186d7459ab9f606506f4ffb75 EN eng Copernicus Publications https://os.copernicus.org/articles/18/587/2022/os-18-587-2022.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-18-587-2022 1812-0784 1812-0792 https://doaj.org/article/12b1e75186d7459ab9f606506f4ffb75 Ocean Science, Vol 18, Pp 587-608 (2022) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2022 ftdoajarticles https://doi.org/10.5194/os-18-587-2022 2022-12-31T02:56:10Z Bubbles formed by breaking waves in the open ocean influence many surface processes but are poorly understood. We report here on detailed bubble size distributions measured during the High Wind Speed Gas Exchange Study (HiWinGS) in the North Atlantic, during four separate storms with hourly averaged wind speeds from 10–27 m s −1 . The measurements focus on the deeper plumes formed by advection downwards (at 2 m depth and below), rather than the initial surface distributions. Our results suggest that bubbles reaching a depth of 2 m have already evolved to form a heterogeneous but statistically stable population in the top 1–2 m of the ocean. These shallow bubble populations are carried downwards by coherent near-surface circulations; bubble evolution at greater depths is consistent with control by local gas saturation, surfactant coatings and pressure. We find that at 2 m the maximum bubble radius observed has a very weak wind speed dependence and is too small to be explained by simple buoyancy arguments. For void fractions greater than 10 −6 , bubble size distributions at 2 m can be fitted by a two-slope power law (with slopes of −0.3 for bubbles of radius <80 µ m and −4.4 for larger sizes). If normalised by void fraction, these distributions collapse to a very narrow range, implying that the bubble population is relatively stable and the void fraction is determined by bubbles spreading out in space rather than changing their size over time. In regions with these relatively high void fractions we see no evidence for slow bubble dissolution. When void fractions are below 10 −6 , the peak volume of the bubble size distribution is more variable and can change systematically across a plume at lower wind speeds, tracking the void fraction. Relatively large bubbles (80 µ m in radius) are observed to persist for several hours in some cases, following periods of very high wind. Our results suggest that local gas supersaturation around the bubble plume may have a strong influence on bubble lifetime, but significantly, ... Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Ocean Science 18 3 587 608 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 H. Czerski I. M. Brooks S. Gunn R. Pascal A. Matei B. Blomquist Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
Bubbles formed by breaking waves in the open ocean influence many surface processes but are poorly understood. We report here on detailed bubble size distributions measured during the High Wind Speed Gas Exchange Study (HiWinGS) in the North Atlantic, during four separate storms with hourly averaged wind speeds from 10–27 m s −1 . The measurements focus on the deeper plumes formed by advection downwards (at 2 m depth and below), rather than the initial surface distributions. Our results suggest that bubbles reaching a depth of 2 m have already evolved to form a heterogeneous but statistically stable population in the top 1–2 m of the ocean. These shallow bubble populations are carried downwards by coherent near-surface circulations; bubble evolution at greater depths is consistent with control by local gas saturation, surfactant coatings and pressure. We find that at 2 m the maximum bubble radius observed has a very weak wind speed dependence and is too small to be explained by simple buoyancy arguments. For void fractions greater than 10 −6 , bubble size distributions at 2 m can be fitted by a two-slope power law (with slopes of −0.3 for bubbles of radius <80 µ m and −4.4 for larger sizes). If normalised by void fraction, these distributions collapse to a very narrow range, implying that the bubble population is relatively stable and the void fraction is determined by bubbles spreading out in space rather than changing their size over time. In regions with these relatively high void fractions we see no evidence for slow bubble dissolution. When void fractions are below 10 −6 , the peak volume of the bubble size distribution is more variable and can change systematically across a plume at lower wind speeds, tracking the void fraction. Relatively large bubbles (80 µ m in radius) are observed to persist for several hours in some cases, following periods of very high wind. Our results suggest that local gas supersaturation around the bubble plume may have a strong influence on bubble lifetime, but significantly, ... |
format |
Article in Journal/Newspaper |
author |
H. Czerski I. M. Brooks S. Gunn R. Pascal A. Matei B. Blomquist |
author_facet |
H. Czerski I. M. Brooks S. Gunn R. Pascal A. Matei B. Blomquist |
author_sort |
H. Czerski |
title |
Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics |
title_short |
Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics |
title_full |
Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics |
title_fullStr |
Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics |
title_full_unstemmed |
Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics |
title_sort |
ocean bubbles under high wind conditions – part 2: bubble size distributions and implications for models of bubble dynamics |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/os-18-587-2022 https://doaj.org/article/12b1e75186d7459ab9f606506f4ffb75 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Ocean Science, Vol 18, Pp 587-608 (2022) |
op_relation |
https://os.copernicus.org/articles/18/587/2022/os-18-587-2022.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-18-587-2022 1812-0784 1812-0792 https://doaj.org/article/12b1e75186d7459ab9f606506f4ffb75 |
op_doi |
https://doi.org/10.5194/os-18-587-2022 |
container_title |
Ocean Science |
container_volume |
18 |
container_issue |
3 |
container_start_page |
587 |
op_container_end_page |
608 |
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1766136324080795648 |