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binntho

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Re: Tides
« Reply #150 on: August 12, 2020, 12:56:51 PM »
JayW, a couple of interesting papers, which don't really have a bearing on what I've been saying. Both of them are about effects outside of the Arctic Ocean proper, one being in the CAA and the other in the Kara between Yamal peninsula and Novaya Zemlya.

Both places have complex coastal contour and bathymetry, and both experience a tidal effect that is larger than in the Arctic Ocean. And neither paper claims a large effect from the tidal movements.

But of course, both of them are interesting and add to the general picture of the effects of tides in the Oceans in general and the Arctic in particular: Small and localized.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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oren

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Re: Tides
« Reply #151 on: August 12, 2020, 01:27:01 PM »
Quote
There is no "transported water" in the open ocean. That's the whole point. The "bulge" attracts water to itself laterally (as I have conceded). But the bulge does not move any water as it itself moves, as you have yourself just agreed.
Binntho you again continue along this illogical path.
The bulge attracts water laterally, yet there is no transported water in the open ocean. How can this be I wonder?
Imagine a region in the Arctic ocean, north of Svalbard. At one time the water is lower by one meter or half meter compared to 6 hours later. Where did all this large volume of water come from? You bet, it came from elsewhere. Was it transported? What else would you call it? There is a net volume inflow into that region, and 6 hours later there is net volume outflow. No way around it I'm afraid,
« Last Edit: August 12, 2020, 02:14:16 PM by oren »

uniquorn

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Re: Tides
« Reply #152 on: August 12, 2020, 01:33:46 PM »
Regarding the Yermak plateau
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/92JC01097
Thank you JayW. A very interesting paper about a plateau north of Svalbard



In my humble opinion, ~7E to ~13E is significant. Then there is the shelf break all along the Nansen basin
« Last Edit: August 12, 2020, 02:00:35 PM by uniquorn »

blumenkraft

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Re: Tides
« Reply #153 on: August 12, 2020, 02:50:12 PM »
Regarding the Yermak plateau
Quote
... We review simple models of tidal current amplification in this region and find that the previous assumption of near‐resonant, barotropic shelf waves propagating around the plateau's entire perimeter is inconsistent with the true topography.

I remember overlaying the bathymetry on that movement some time ago. I thought i must have done it wrongly since the Plateau and the waves didn't match. The movement occurred a little further north. So this quoted part is especially interesting to me. Looks like this finding confirmes my overlay was correct after all.  8)

Also, check the upper right in the GIF above there seems to be a similar movement where the ice edge is at the moment. This is a little north to the southern elevation of the Yermak Plateau.

Binntho, if your 'in/out just the same thing' argument was true, you would see the same feature in the south of both points asynchronously. But there is no such movement there.
« Last Edit: August 12, 2020, 02:57:39 PM by blumenkraft »
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uniquorn

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Re: Tides
« Reply #154 on: August 12, 2020, 02:59:00 PM »
The turbulence appears north of the shelf. Depth rises from ~4000m to ~800m. We could do with a few more rammb's of that area to attempt to verify a daily event. Maybe in their own thread. There are currents here too, so tide will only be a contributary factor.



There aslo eddies west of the plateau and the molloy hole, of course.

johnm33

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Re: Tides
« Reply #155 on: August 13, 2020, 03:11:01 PM »
Bit of housekeeping, Gero. posted a link to this on the season page. https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2020GL089469
"Measurements of currents from a 15-year duration mooring record in the eastern Eurasian
Basin of the Arctic Ocean demonstrate that the previously identified weakening of
stratification in the halocline (e.g., Polyakov et al., 2017, 2018) has been accompanied by
increased upper-ocean current speeds and associated current shear. Most of this increased
energy and shear is in the semidiurnal band, which includes baroclinic tides and wind-driven
inertial oscillations, with little change of mean along-slope water transport (Pnyushkov et al.,
2018). "

blumenkraft

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Re: Tides
« Reply #156 on: August 13, 2020, 03:31:36 PM »
Here is a tidal swirl in the CAB. Somewhere a little east of the Lomonosov Ridge. The ocean is very deep here and the shores are far away!
« Last Edit: August 13, 2020, 03:40:20 PM by blumenkraft »
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uniquorn

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Re: Tides
« Reply #157 on: August 13, 2020, 10:13:47 PM »
Another couple of references

Baroclinic Tides: Theoretical Modeling and Observational Evidence
Vasiliy Vlasenko, Nataliya Stashchuk, Kolumban Hutter
Quote
This book was first published in 2005. When an oceanic tidal wave that is primarily active on the water surface passes an ocean shelf or a region with a seamount, it is split into a less energetic surface wave and other internal modes with different wavelengths and propagation speeds. This cascading process, from the barotropic tides to the baroclinic components, leads to the transformation of tidal energy into turbulence and heat, an important process for the dynamics of the lower ocean. Baroclinic Tides demonstrates the analytical and numerical methods used to study the generation and evolution of baroclinic tides and, by comparison with experiments and observational data, shows how to distinguish and interpret internal waves.


https://www.sciencedirect.com/science/article/abs/pii/S0079661197000281
Quote
Abstract

An approximate estimate of the energy in the first mode M2 baroclinic tide has been made from satellite observations. Results based on TOPEX/POSEIDON (T/P) precision altimetry indicate that the internal tide patterns are similar to those expected from mid-ocean topographic features in the global oceans. Both the orthotide and harmonic analyses indicate that the total energy in global M2 baroclinic tide is approximately 50 PJ. For a variety of reasons, M2 is the only component that can be obtained reliably from altimetric measurements. Even then, the energy value may be an underestimate and the energy flux, the dissipation rate, cannot be deduced from altimetry. Since it is the tidal currents flowing over mid-ocean topographic features that are responsible for generating internal tides, a model calibrated by M2 observations is a plausible alternative. Currents from a high resolution (
) barotropic tidal model have therefore been used to obtain an estimate of both the energy and the dissipation rate in M2, S2 and K1 baroclinic tides. A simple model of baroclinic tide generation has been used, and the unknown constant in this model has been selected to yield a total energy of 50 PJ in the first mode M2 baroclinic tide. Based on this calibration, the total energy is 8 PJ in S2 first mode baroclinic tide and 15 PJ in K1. The total in all first mode baroclinic tides is 90 PJ, about 16% of the total energy (580 PJ) in barotropic tides. The model results also suggest that about 360 GW of tidal energy are dissipated in M2 baroclinic tides alone, and 520 GW are dissipated in all first mode baroclinic tides. The latter value is approximately 15% of the power input into barotropic ocean tides (3490 GW) by the lunisolar tidal forces. We have preferred to be conservative and hence these are likely to be underestimates, especially since the altimetric tracks do not often intersect mid-ocean topographic features at optimum angles. While these values are very much within the range of earlier estimates in literature, they should be regarded as still uncertain to perhaps a factor of two (the dissipation rate could be anywhere from 400 GW to 800 GW, the most likely value being about 600 GW). The small signal to noise ratio involved in altimetric measurements of the surface manifestation of internal tides, and potential contamination by mesoscale signals are serious problems. In situ measurements at least a few locations underneath altimetric tracks are essential for confirmation and/or refinement of these preliminary estimates. Hopefully, these very first estimates of the energy and dissipation rate in global baroclinic tides, though rather crude, will serve as a catalyst for a better estimation in the future, since internal tides are likely to be a prominent source of mixing in the deep oceans and important to thermocline maintenance.

Quick bathy overlay using worldview, aug11   https://go.nasa.gov/30W1WR0
85.2N 157.4E  1100m drops to 3800m
(then back up to 2400m at 172.2E under the furthest east low conc area. Not sure if that is relevant)
« Last Edit: August 13, 2020, 11:12:22 PM by uniquorn »

uniquorn

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Re: Tides
« Reply #158 on: August 14, 2020, 03:51:59 PM »
https://twitter.com/seaice_de/status/1293073783830478848
Some interesting short videos on the thread, near FJL on the way to Polarstern

uniquorn

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Re: Tides
« Reply #159 on: August 14, 2020, 05:02:03 PM »
October 2, 2015
https://tos.org/oceanography/assets/docs/24-3_rainville.pdf
Quote
The Arctic Ocean traditionally has been described as an ocean with low variability and weak turbulence levels. Many years of observations from ice camps and ice-based instruments have shown that the sea ice cover effectively isolates the water column from direct wind forcing and damps existing motions, resulting in relatively small upper-ocean variability and an internal wave field that is much weaker than at lower latitudes. Under the ice, direct and indirect estimates across the Arctic basins suggest that turbulent mixing does not play a significant role in the general distribution of oceanic properties and the evolution of Arctic water masses. However, during ice-free periods, the wind generates inertial motions and internal waves, and contributes to deepening of the mixed layer both on the shelves and over the deep basins—as at lower latitudes. Through their associated vertical mixing, these motions can alter the distribution of properties in the water column. With an increasing fraction of the Arctic Ocean becoming ice-free in summer and in fall, there is a crucial need for a better understanding of the impact of direct wind forcing on the Arctic Ocean.


johnm33

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Re: Tides
« Reply #160 on: Today at 12:16:45 AM »
Looking at the 'Lomonosov eddy' it's difficult  to see what else could be causing that apart from basal movement. The simplest would be Atl.W. displacing water from the Wrangel abyssal plain, moving it towards the pole through perhaps both the narrower part of the Makarov basin and also Nemilov valley and since in both cases the water is moving directly towards the pole it has to shed angular momentum. I would expect such phenomenon to be short lived [if anything] simply because of the layers they have to penetrate but there are signs of them being there or thereabouts for days which may mean whatever real forcings are occuring they are in the first[?] stages of establishing a current, it is a natural path for a current to follow and probably the hardest part of overcoming the inertia of such a massive volume of water is creating the initial movement.
More widely the build up of the next tidal cycle has begun and I would expect an acceleration of Atl. waters moving north of Greenland to continue the damage being done there, we may also see waters forcing there way through to Baffin the morning of the 18th being the soonest and potentially the most game changing, especially if a surface current becomes established.