Unpredictability of internal M 2
Current observations from a shelf sea, continental slopes and the abyssal North-East Atlantic Ocean are all dominated by the semidiurnal lunar (M 2 ) tide. It is shown that motions at M 2 vary at usually large barotropic and coherent baroclinic scales, >50 km horizontally and >0.5 H vertically...
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ftdoajarticles:oai:doaj.org/article:75bbbaa3580a45388893501f9fcad3e7 2023-05-15T17:38:35+02:00 Unpredictability of internal M 2 H. van Haren 2007-06-01T00:00:00Z https://doaj.org/article/75bbbaa3580a45388893501f9fcad3e7 EN eng Copernicus Publications http://www.ocean-sci.net/3/337/2007/os-3-337-2007.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/75bbbaa3580a45388893501f9fcad3e7 Ocean Science, Vol 3, Iss 2, Pp 337-344 (2007) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2007 ftdoajarticles 2022-12-30T22:13:49Z Current observations from a shelf sea, continental slopes and the abyssal North-East Atlantic Ocean are all dominated by the semidiurnal lunar (M 2 ) tide. It is shown that motions at M 2 vary at usually large barotropic and coherent baroclinic scales, >50 km horizontally and >0.5 H vertically. H represents the waterdepth. Such M 2 -scales are observed even close to topography, the potential source of baroclinic, "internal" tidal waves. In contrast, incoherent small-scale, ~10 km horizontally and ~0.1 H vertically, baroclinic motions are dominated around f, the local inertial frequency, and/or near 2Ω≈S 2 , the semidiurnal solar tidal frequency. Ω represents the Earth's rotational vector. This confirms earlier suggestions that small-scale baroclinic M 2 -motions generally do not exist in the ocean in any predictable manner, except in beams very near, <10 km horizontally, to their source. As a result, M 2 -motions are not directly important for generating shear and internal wave induced mixing. Indirectly however, they may contribute to ocean mixing if transfer to small-scale motions at f and/or S 2 and at high internal wave frequencies can be proven. Also far from topography, small-scale motions are found at either one or both of the latter frequencies. Different suggestions for the scales at these particular frequencies are discussed, ranging from the variability of "background" density gradients and associated divergence and focusing of internal wave rays to the removal of the internal tidal energy by non-linear interactions. Near f and S 2 particular short-wave inertio-gravity wave bounds are found in the limits of strong and very weak stratification, which are often observed in small-scale layers. Article in Journal/Newspaper North East Atlantic Directory of Open Access Journals: DOAJ Articles |
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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. van Haren Unpredictability of internal M 2 |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
Current observations from a shelf sea, continental slopes and the abyssal North-East Atlantic Ocean are all dominated by the semidiurnal lunar (M 2 ) tide. It is shown that motions at M 2 vary at usually large barotropic and coherent baroclinic scales, >50 km horizontally and >0.5 H vertically. H represents the waterdepth. Such M 2 -scales are observed even close to topography, the potential source of baroclinic, "internal" tidal waves. In contrast, incoherent small-scale, ~10 km horizontally and ~0.1 H vertically, baroclinic motions are dominated around f, the local inertial frequency, and/or near 2Ω≈S 2 , the semidiurnal solar tidal frequency. Ω represents the Earth's rotational vector. This confirms earlier suggestions that small-scale baroclinic M 2 -motions generally do not exist in the ocean in any predictable manner, except in beams very near, <10 km horizontally, to their source. As a result, M 2 -motions are not directly important for generating shear and internal wave induced mixing. Indirectly however, they may contribute to ocean mixing if transfer to small-scale motions at f and/or S 2 and at high internal wave frequencies can be proven. Also far from topography, small-scale motions are found at either one or both of the latter frequencies. Different suggestions for the scales at these particular frequencies are discussed, ranging from the variability of "background" density gradients and associated divergence and focusing of internal wave rays to the removal of the internal tidal energy by non-linear interactions. Near f and S 2 particular short-wave inertio-gravity wave bounds are found in the limits of strong and very weak stratification, which are often observed in small-scale layers. |
format |
Article in Journal/Newspaper |
author |
H. van Haren |
author_facet |
H. van Haren |
author_sort |
H. van Haren |
title |
Unpredictability of internal M 2 |
title_short |
Unpredictability of internal M 2 |
title_full |
Unpredictability of internal M 2 |
title_fullStr |
Unpredictability of internal M 2 |
title_full_unstemmed |
Unpredictability of internal M 2 |
title_sort |
unpredictability of internal m 2 |
publisher |
Copernicus Publications |
publishDate |
2007 |
url |
https://doaj.org/article/75bbbaa3580a45388893501f9fcad3e7 |
genre |
North East Atlantic |
genre_facet |
North East Atlantic |
op_source |
Ocean Science, Vol 3, Iss 2, Pp 337-344 (2007) |
op_relation |
http://www.ocean-sci.net/3/337/2007/os-3-337-2007.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/75bbbaa3580a45388893501f9fcad3e7 |
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1766139096628985856 |