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Freegrass

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Bering Strait
« on: January 20, 2020, 04:50:41 PM »
The changes in the strength and salinity of the bering strait current play a important role in Arctic changes, so I was surprised to see that the Bering Strait didn't have it's own thread here yet.

I believe that the increase in the strength of the bering strait current has to do with a slowdown of the AMOC. Maybe we can start off the discussion with these two papers?

Relations between salinity in the northwestern Bering Sea, the Bering Strait throughflow and sea surface height in the Arctic Ocean
https://link.springer.com/article/10.1007/s10872-017-0453-x


Increases in the Pacific inflow to the Arctic from 1990 to 2015, and insights into seasonal trends and driving mechanisms from year-round Bering Strait mooring data.
http://psc.apl.washington.edu/HLD/Bstrait/BeringStraitSeasonalInterannualChange2017.html

Year-round in situ Bering Strait mooring data (1990-2015) document a long-term increase (~0.01Sv/yr whole record, ~0.02Sv since 2000) in the annual mean transport of Pacific waters into the Arctic.  Between 2002 and present (2015), all annual mean transports (except 2005 and 2012) are greater than the previously accepted climatology (~0.8Sv).
« Last Edit: January 20, 2020, 05:45:30 PM by Freegrass »
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Bruce Steele

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Re: Bering Strait
« Reply #1 on: June 22, 2020, 08:14:45 PM »
Freegrass, There are no buoy arrays currently monitoring Bering inflow rates so you have to read as much as you can by Rebecca Woodgate . She authored a number of papers about a buoy array no longer being maintained.
 She has a 2018 paper on causes of variability in flow rates . “ Most notably, however, we find the increase in the Bering Strait throughflow is due to a strong increase in the pressure-head forcing of the flow, consistent through most of the year, reflecting the naturally longer timescales of the far-field forcing of the flow. ”



  http://psc.apl.washington.edu/HLD/Bstrait/BeringStraitSeasonalInterannualChange2017.html

Here is another older link that includes Chukchi circulation 101



http://psc.apl.washington.edu/HLD/Chukchi/Chukchi.html


I didn’t think I wanted to post on the melting season .  Just read Woodgate .




« Last Edit: June 24, 2020, 01:34:18 AM by Bruce Steele »

Sebastian Jones

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Re: Bering Strait
« Reply #2 on: June 23, 2020, 09:08:10 PM »
For an entertaining series of posts regarding the Bering Strait, I might suggest TM Mallard and his thread on damming the straits in order to refreeze the Arctic Ocean, raise global albedo and arrest global warming:
https://forum.arctic-sea-ice.net/index.php/topic,1545.0.html

Freegrass

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Re: Bering Strait
« Reply #3 on: June 23, 2020, 10:01:32 PM »
No buoys monitoring the Bering Strait? How is that possible at such an important strait? I guess it would be difficult to place buoys there with all that ice passing through, but surely it would be possible to place some on the seafloor?

I'll check out Rebecca Woodgate. Thanks for that!

The one article I found was given to me by someone on this forum, and I posted here. It showed an increase of the inflow. That's why I became convinced that a slowdown of the AMOC must be increasing the inflow through the Bering Strait, but I lack way to much knowledge to figure that out myself. I keep hoping I can convince someone else of my theory, but nobody seems to want to bite.  :'(

What do you think? Does my theory make sense?
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Bruce Steele

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Re: Bering Strait
« Reply #4 on: June 24, 2020, 01:57:03 AM »
Freegrass, I went back and added a quote from the Woodgate 2017 paper . So a difference in sea height between the Atlantic and the North Pacific seems to be the reason for the increased inflow or would explain it.
 I don’t have enough knowledge to speculate why.
 

Freegrass

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Re: Bering Strait
« Reply #5 on: June 24, 2020, 03:14:23 AM »
I think it's logical to assume that when the inflow from the AMOC goes down by 15%, that the water level must go down as well. But that's just my reasoning. I have absolutely no prove for that speculation.

I do think it's an important development for the Arctic Ocean that needs attention. If the inflow through the Bering strait does indeed increase, that would mean that increasingly hotter water from the Pacific can melt more ice. And that would be a bad development...

My solution would be to drop a lot of rocks into the Bering Strait to reduce the flow...
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oren

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Re: Bering Strait
« Reply #6 on: June 24, 2020, 08:06:48 AM »
FG don't fall into the trap of simplistic models. The Arctic water balance is made up of many currents and not just AMOC + Bering. In addition there's evaporation, precipitation, river discharge, wind driven water+ice movement, general SLR and more.
Besides, is the Bering flow indeed increasing? Is the AMOC indeed decreasing? Without a chain of tethered buoys all around the Arctic, that is hard to quantify and prove.
Note damming the Bering Strait belongs in the other thread mentioned above.

Freegrass

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Re: Bering Strait
« Reply #7 on: July 12, 2020, 01:25:18 AM »
VoxM posted this in the melting thread, and I wonder if this confirms part of my theory. I believe it shows that the water coming through the Bering Strait is hotter, and faster flowing, and is already causing a lot of damage to the ice in the Chukchi. (I will post about this later in the melting thread).

I think this message belongs here, I just have a hard time understanding it. I hope someone can help me out here. Why is the Bering Strait inflow such a poorly debated topic on ASIF?

I don't usually have anything relevant to add here, but this came out today and seems to be topical ...

Arctic Ocean Changes Driven by Sub-Arctic Seas
https://phys.org/news/2020-07-arctic-ocean-driven-sub-arctic-seas.html

New research explores how lower-latitude oceans drive complex changes in the Arctic Ocean, pushing the region into a new reality distinct from the 20th-century norm.



The University of Alaska Fairbanks and Finnish Meteorological Institute led the international effort, which included researchers from six countries. The first of several related papers was published this month in Frontiers in Marine Science.

The Arctic Ocean, which covers less than 3% of the Earth's surface, appears to be quite sensitive to abnormal conditions in lower-latitude oceans.

"With this in mind, the goal of our research was to illustrate the part of Arctic climate change driven by anomalous [different from the norm] influxes of oceanic water from the Atlantic Ocean and the Pacific Ocean, a process which we refer to as borealization," said lead author Igor Polyakov, an oceanographer at UAF's International Arctic Research Center and FMI


This conceptual model shows the influx of Pacific and Atlantic water into the Arctic Ocean in the past compared to recent years. Blue indicates cool water and red indicates warm water. Arrows indicate the direction of water flow.

Since the first temperature and salinity measurements taken in the late 1800s, scientists have known that cold and relatively fresh water, which is lighter than salty water, floats at the surface of the Arctic Ocean. This fresh layer blocks the warmth of the deeper water from melting sea ice.

In the Eurasian Basin, that is changing. Abnormal influx of warm, salty Atlantic water destabilizes the water column, making it more susceptible to mixing. The cool, fresh protective upper ocean layer is weakening and the ice is becoming vulnerable to heat from deeper in the ocean. As mixing and sea ice decay continues, the process accelerates. The ocean becomes more biologically productive as deeper, nutrient-rich water reaches the surface.

By contrast, increased influx of warm, relatively fresh Pacific water and local processes like sea ice melt and accumulation of river water make the separation between the surface and deep layers more pronounced on the Amerasian side of the Arctic. As the pool of fresh water grows, it limits mixing and the movement of nutrients to the surface, potentially making the region less biologically productive. ...


Vertical profiles of winter (NDJFMA) potential temperature (θ, left column, °C, A,C,E,G) and salinity (S, right column, psu, B,D,F,H) for the central points of the four selected regions of the Arctic Ocean (regions are identified in the right column, their geographical locations are shown in Figure 1) from the 1970s (blue) and 2000s-2010s (red). CHL, NSTM, PSW, and PWW identify Cold Halocline Layer, Near-Surface Temperature Maximum, Pacific Summer Water and Pacific Winter Water.

Igor V. Polyakov et al, Borealization of the Arctic Ocean in Response to Anomalous Advection From Sub-Arctic Seas, Frontiers in Marine Science (2020).
https://www.frontiersin.org/articles/10.3389/fmars.2020.00491/full




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Re: Bering Strait
« Reply #8 on: July 12, 2020, 05:12:37 PM »
If you had a swimming pool and two sources of water a drinking straw a pipe big enough to climb into, when trying to fill up the pool which one would you pay more attention to? Having said that now I am wondering how big the cross sectional areas are for each entrance into the Arctic.

Freegrass

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Re: Bering Strait
« Reply #9 on: July 13, 2020, 03:35:57 AM »
If you had a swimming pool and two sources of water a drinking straw a pipe big enough to climb into, when trying to fill up the pool which one would you pay more attention to? Having said that now I am wondering how big the cross sectional areas are for each entrance into the Arctic.
If that big pipe gets closed a little, and the little straw with hot water starts burning your back because it just started flowing harder, I think you will start to notice the little straw... ;)

Just found another paper.

Accepted Geophysical Research Letters, November 2012

Key Points: Bering Strait volume, heat and freshwater fluxes increase ~50% from 2001-2011. Most of this is due to a ~30% increase in the Pacific-Arctic pressure-head. Near constant maximum summer salinities set Arctic cold halocline properties.
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Re: Bering Strait
« Reply #10 on: July 13, 2020, 10:32:46 PM »
I am not trying to imply their is no impact from changes on the pacific side. I am just saying one is more important than the other. As a reason why the forum doesn't pay much attention to it. My perception is it has become more of a factor than it was when I started following Arctic melt.

vox_mundi

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Re: Bering Strait
« Reply #11 on: September 02, 2020, 10:18:43 PM »
Bering Sea Ice Extent Is At Most Reduced State In At Least Last 5,500 Years
https://phys.org/news/2020-09-bering-sea-ice-extent-state.html

A newly published paper in the journal Science Advances describes how a peat core from St. Matthew Island is providing a look back in time. By analyzing the chemical composition of the core, which includes plant remains from 5,500 years ago to the present, scientists can estimate how sea ice in the region has changed during that time period.

"It's a small island in the middle of the Bering Sea, and it's essentially been recording what's happening in the ocean and atmosphere around it," said lead author Miriam Jones, a research geologist with the U.S. Geological Survey. Jones worked as a faculty researcher at the University of Alaska Fairbanks when the project began in 2012.



The ancient sea ice record comes in the form of changes in the relative amounts of two isotopes of the element oxygen— oxygen-16 and oxygen-18. The ratio of those two isotopes changes depending on patterns in the atmosphere and ocean, reflecting the different signatures that precipitation has around the globe. More oxygen-18 makes for an isotopically "heavier" precipitation, more oxygen-16 makes precipitation "lighter."

By analyzing data from a model that tracks atmospheric movement using the isotopic signature of precipitation, the authors found that heavier precipitation originated from the North Pacific, while lighter precipitation originated from the Arctic.

A "heavy" ratio signals a seasonal pattern that causes the amount of sea ice to decrease. A "light" ratio indicates a season with more sea ice. That connection has been confirmed though sea ice satellite data collected since 1979, and to a smaller extent, through the presence of some microorganisms in previous core samples.

"What we've seen most recently is unprecedented in the last 5,500 years," said Matthew Wooller, director of the Alaska Stable Isotope Facility and a contributor to the paper. "We haven't seen anything like this in terms of sea ice in the Bering Sea."

Jones said the long-term findings also affirm that reductions in Bering Sea ice are due to more than recent higher temperatures associated with global warming. Atmospheric and ocean currents, which are also affected by climate change, play a larger role in the presence of sea ice.

"There's a lot more going on than simply warming temperatures," Jones said. "We're seeing a shift in circulation patterns both in the ocean and the atmosphere."





M.C. Jones el al., "High sensitivity of Bering Sea winter sea ice to winter insolation and carbon dioxide over the last 5500 years," Science Advances (2020).
https://advances.sciencemag.org/content/6/36/eaaz9588

... The substantial rate of anthropogenic CO2 inputs into the atmosphere over industrialization suggests that a loss in Bering Sea sea ice extent is accelerating or is already committed to complete sea ice loss as a result of delayed response to anthropogenic forcing. Low winter sea ice anomalies in CE 2018 and CE 2019 indicate future conditions that favor an ice-free Bering Sea. Widespread effects of Bering Sea winter sea ice loss are expected to occur. Ecosystem responses to low sea ice in CE 2018 included altered food webs that led to sea bird die-offs and may represent a harbinger of future low sea ice extent.

Further intensification of observed North Pacific influence in the Bering Sea leading to a reduction in sea ice can further affect heat transport to the Arctic Ocean basin. Although the Bering Strait throughflow may be relatively small (<1 Sv; 1 Sv = 106 m3 s−1), it can have a disproportionate influence on heatflux into the Arctic Ocean basin, and recent increases have been linked to weakening northerly winds (32), signifying enhanced winds originating from the North Pacific could amplify Arctic Ocean sea ice decline via increasing winds from the south.

Simultaneously, the increased frequency and duration of winter cyclones in the Arctic have led to the large reductions in freezing degree days in Arctic Ocean winters (33, 34). A loss of sea ice can also increase coastal erosion and increase land temperatures that result in permafrost thaw (35), further amplifying warming (36).
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