Reversal of the Siberian Coastal Current

[Freegrass]

When you look at the Siberian Coastal Current (SCC) for the last few days on Nullschool, you can clearly see that the SCC is reversed. The current coming out of the Bering Strait is now flowing into the ESS. I'm wondering if this is a glitch in the data, or if something else is going on here.

Looking at the salinity data in this area this phenomenon seems to be confirmed.

Is there a simple explanation for this, or can we start speaking about the pacification of the ESS?

Attached are 2 GIFs with salinity at 30 meters and the surface comparing 2019 with 2020.

[KenB]

Attached are 2 GIFs with salinity at 30 meters and the surface comparing 2019 with 2020.

Maybe it's just me, but I only get the 2019 images here.

[blumenkraft]

Click to play, Ken.

[bbr2315]

I believe Freegrass is correct and that HYCOM confirms this reversal. To me it looks like the ATL front has advanced all the way to Laptev Shelf / Eurasia roughly at the outlet of the Khatanga River.



To my eyes it looks like the Bering is now pushing NW, which combined with the NW ATL front is now dislodging the freshwaters of the ESS into the Chukchi / Beaufort.

[KenB]

Click to play, Ken.

Hmm, I'd swear I did before, but it's working fine now.  So maybe not :-).

[Freegrass]

I sometimes have the same problem Ken. Refreshing the page usually does the trick.

[FishOutofWater]

It's real.

Prolonged high pressure caused easterly winds around the Arctic shores and shelves and high sea surface heights built up offshore while lower sea surface heights were near shore in the eastern Siberian and Chukchi seas. It's not just an effect of mixing and no sea ice like I previously concluded.

Take a look at the Mercator SSH maps and animations and you will see the anomalous SSH pattern caused by many days of high pressure over the pole.

You can see a surge of warm water through the Bering Strait at 30 m into the Chukchi sea that goes both towards Siberia and Towards the Alaskan coast over the past 50 days. Some of that is normal seasonal warming of the water. However, high pressure over the pole causes and influx of water towards the high pressure area. This influx of warm, somewhat salty water will add to the melting of the remaining sea ice as the storm disperses ice into the warm water over the next 5 days. For an animation at Mercator click the link:

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20200601/20200725/1/2

You know, what's even more disturbing than the flux of water into the Chukchi sea is the powerful flux of saline Atlantic water into the Laptev sea. This prolonged high pressure event has pulled large amounts of saline water into the coastal seas of the Arctic ocean.

[FishOutofWater]

It's even more disturbing that a current from the Bering strait flowing on the east Siberia shoreline. High pressure can do that. Salty water is flowing off the Chukchi platform into the Beaufort sea at the 100m level. The surge of Pacific water is affecting the whole Chukchi platform and is beginning to affect the adjacent seas down to 100 meters depth. Another explanation of this feature might be the upwelling of Atlantic layer water on the continental shelf margin.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20200601/20200725/2/3

[johnm33]

I think the prolonged high pressure had to force 20cm of water away from the epicenter, in the end the only route thats constantly available is over Lomonosov, so both the in-situe mass and the added mass from compaction established a flow loosely towards Fram once the flow began it had a kind of flywheel effect and pulled the Pacific waters in it's wake.  From the Asian side there exists a current that regularly flows this route and i suspect that is drawn in that direction by the flow of Atlantic waters which having insufficient kinetic energy, or being simply too dense is halted by the Chukchi plateau and falls and finds it's level above the Makarov basin and here either recycles towards Fram or drives other water in it's stead. So possibly the excess waters from the high follow above this route?
We now find ourselves looking at the Pacific side of Lomonosov being somewhat depleted and the low in it's turn attracting more water i don't think a reversal of the Pacific inflow[towards Beaufort] is the most likely, what i expect is a tidally moderated flow from the Atlantic forcing it's way across N.Greenland and Ellesmere/Axel-Heiberg Is. creating turbulence/vortices which will remove all coastal ice from the shelf. That'll flow into Beaufort and an enhanced flow west from Banks island is likely, and there may be some drawn down Nares but reversal of flows through the CAA. NWPs. So more Atl. waters into both the ESS and Beaufort, but we'll see.

[Freegrass]

So it is weather related, and not a more fundamental change. That's good to know! I thought that maybe an increase of the speed of the current caused it to take a new path due to some mechanical force.

The next question is what all that saltier water will do to the methane clathrates in the ESS.

But I'm so happy I finally have an answer.    Thank you so much FOoW! Now I can sleep better.

[Rod]

Added a few more buoys to the drift animation. Someone is collecting a large swath of data in the Beaufort/Chukchi

I’m cross posting this great animation from uniquorn (below) from the buoy thread. It certainly supports what the models are showing.

I also think this paper has some helpful information. It supports what FOOW said and provides a few more details. This is an interesting topic Freegrass. Thanks for bringing it up!

The distribution of water masses and their circulation on the western Chukchi Sea shelf are investigated using shipboard data from the 2009 Russian-American Long Term Census of the Arctic (RUSALCA) pro- gram. Eleven hydrographic/velocity transects were occupied during September of that year, including a number of sections in the vicinity of Wrangel Island and Herald canyon, an area with historically few measurements. We focus on four water masses: Alaskan coastal water (ACW), summer Bering Sea water (BSW), Siberian coastal water (SCW), and remnant Pacific winter water (RWW). In some respects the spatial distributions of these water masses were similar to the patterns found in the historical World Ocean Database, but there were significant differences. Most notably, the ACW and BSW were transposed in Bering Strait, and the ACW was diverted from its normal coastal pathway northwestward through Herald Canyon. It is argued that this was the result of atmospheric forcing. September 2009 was char- acterized by an abnormally deep Aleutian Low and the presence of the Siberian High, which is normally absent this time of year. This resulted in strong northerly winds during the month, and mooring data from the RUSALCA program reveal that the ACW and BSW were transposed in Bering Strait for a sig- nificant portion of the month. Using an idealized numerical model we show that the Ekman response to the wind can cause such a transposition, and that the consequences of this will persist on the shelf long after the winds subside. This can explain the anomalous presence of ACW in Herald Canyon during the RUSALCA survey.

There  are several ramifications of such a wind-driven trans- position of ACW and BSW. Much of the heat and freshwater transported into the Chukchi Sea, and ultimately fluxed into the interior basin, is carried by the Alaskan Coastal Current. The heat is capable of melting a significant amount of pack-ice, while the freshwater can contribute to the reservoir of freshwater within the Beaufort gyre. If ACW is diverted from its normal coastal route within the Alaskan Coastal Current it will (1) reside longer on the Chukchi shelf due to the longer and slower pathways on the central/western shelf, plus the fact that northerly winds retard the flow; and (2) exit the Chukchi shelf at a different lo- cation and possibly in a different manner. internal citations omitted

   

https://rpickart.whoi.edu/wp-content/uploads/sites/53/2016/02/pisareva_etal_2015_dsr.pdf

[Freegrass]

This is an interesting topic Freegrass. Thanks for bringing it up!

You're welcome. I knew it was something important that I saw happening, I just didn't know why it was happening and what the consequences are. Thank you all for helping me to understand it better. I'm sure the last word isn't said about this phenomenon yet. So I'll leave you all to it now. I'll just read and learn.

[oren]

Something not yet mentioned here: The current coming north out of the Bering Strait has momentum in the direction of the Earth's rotation, and thus must turn right (east) towards the Beaufort due to the Coriolis effect. Therefore its turning towards Siberia has to be weather related, and once the weather returns to normal the current will tend to go back east.

[Rod]

That is certainly a good point oren. But the other issue, which I think Freegrass raised, is what happens with all of the pacific water that has already collected on the Chukchi shelf?

According to the 2009 Russian-American survey, it can persist for a while, do some damage, and its ultimate exit path is unpredictable.

It is an interesting topic. The last thing we want is warm salty water eating away at the subsea permafrost in the ESAS.

[Freegrass]

If the current does reverse back to its original state, then the SCC should flush all that salt water back out of the ESS again. Unless of course the salt water settles at the bottom of the ESS and the fresh water flows on top of it. But I'm guessing the ESS is too shallow for that?

The question then becomes how long it will take for that salt water to get flushed out again and if it will do so before it can do some serious damage to the clathrates.

[Rod]

I’m not sure it is that simple Freegrass. The paper I cited above provides some relevant information:

Due to the relative dearth of measurements on the western Chukchi shelf, the precise pathways and modification of the Pacific origin water in this region are presently not well understood. Many open questions exist regarding the geographical distributions and seasonal modifications of the water. This includes the relative influences of upstream forcing (Bering Strait) versus atmospheric forcing in steering and modifying the water, and the manner in which the water on the Chukchi shelf interacts with that on the East Siberian shelf and in the deep Arctic basin, including the Atlantic water.

Also, this is a minor point, but when talking about the methane in the ESAS it is best not to refer to it as clathrates. There may be some clathrates in the permafrost. Shakhova thinks there are. But, she has also said that is irrelevant.

There is no dispute that there is a lot of methane in the ESAS. It does not matter if the methane is free and frozen in the ice pockets, or trapped in a frozen H2O cage (clathrates). But, that distinction gives deniers something to latch onto and argue about.

 

[Freegrass]

I wasn't aware that clathrates was a loaded term. I will not use it again! Thanks for pointing that out to me.

[FishOutofWater]

There are several canyons on the Beaufort sea side of the Chukchi shelf. The Mercator animation shows shelf water flowing into those canyons and into the Beaufort sea. The problem for the ESS shelf is not Pacific water. The Siberian shelf is has a large influx of water from Siberian rivers. With this summer's record heat, the river water is hot when it enters the Siberian seas. That's the water that may be affecting the permafrost in the Siberian shelf sediments.

The Coriolis effect always applies and will tend to turn water to the right if there isn't an effect of weather, physical obstacles like islands, or ocean dynamics like eddies and flow down submarine canyons.

[Pmt111500]

I wasn't aware that clathrates was a loaded term. I will not use it again! Thanks for pointing that out to me.

Clathrates are just in a way deeper in the water than the soil locked carbon in the bottom of the Siberian Seas. Nothing loaded about the term but not the correct one wrt to methane seeps in shallow water. (Have made this mistake myself too then someone here said they're not the same stuff.)

[pearscot]

I'm not even sure if it is possible, but one thing I have often thought about is somehow the Atlantic and Pacific currents meeting in the central arctic or in the Siberian coastal area.

Granted, I'm not even sure if that's possible, but at the same time it doesn't surprise me to see all of the Arctic seas begin to experience more Atlantification.

[Freegrass]

The latest update on Nullschool is showing the SCC back to kinda normal.

https://earth.nullschool.net/#current/ocean/surface/currents/orthographic=-185.07,72.45,3000

I guess now we wait to see what'll happen with all the salt water in the ESS.

PS: isn't that water in the beaufort a little too salty? 

[Bruce Steele]

Freegrass, The wind had been predominantly North for a couple months and that kept the buoys and water masses headed west for a long time. One of the buoys Uniquorn showed moved most of the distance from Wrangell island to the New Siberian Islands in two months. Things seem to have changed for now.
 The best conditions for Pacific water  inflow through the Bering Straits is with long periods of Southerly winds in that area. We have been getting Southerly winds and the one weather station I know of North of the Bering Straits is now recording increasing water temperatures. 52 F today.  At Red Dog Dock you can watch as the wind direction affects water temperatures. The site allows you to scroll back through months of data. 
https://www.ndbc.noaa.gov/station_page.php?station=rdda2

[Freegrass]

Thanks Bruce. I'll check it out.

I think it's obvious now that the reversal happened because of the GAAC. This will definitely be something to keep an eye on next time we have a weather situation like that.

Now we watch to see what all that salt will do to the ESS, and how long it will take for that salt to be removed again.

[Freegrass]

The SCC has changed direction again I just noticed...

https://earth.nullschool.net/#current/ocean/surface/currents/orthographic=-45.02,91.24,2304