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Cooler Atlantic

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Oceanography was a job that i hoped would turn into a life long career but family issues forced me to change my path in life but i still follow all i can on the subject.

I don't believe the AMOC will stop like some doom sayers mention but even a small reduction in the flow will and i believe already has begun to change the weather in the UK.

 

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Differences globally but 2000 is the most similar recent year for the Atlantic SST pattern..

anomnight.6.20.2000.gif

anomnight.5_31_2018.thumb.gif.06db8c17af

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Nice spot SB. Interesting how it's so similar globally (allowing for overall warming of the Pacific) yet pretty much a complete reverse in the vicinity of the UK 🤔.

Edited by Singularity

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29 minutes ago, Singularity said:

Nice spot SB. Interesting how it's so similar globally (allowing for overall warming of the Pacific) yet pretty much a complete reverse in the vicinity of the UK 🤔.

Some of that could be down to ice melt possibly. We know that in a lot of years the North Pacific looks absurdly cold for few weeks on the anomolies but it usually clears itself up (obviously looks worse in -PDO years).

I would also add for those who believe the Met Office's May SST-Winter NAO link, this is a horrifically awful pattern. The exact opposite tripole to what we want. 

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I see I still have some reach. :D

I do have in plan to do a post on Atlantic with some more data, like different depths and also salinity anomalies. Might also add a cross-section or two. All from the well respected datasets MERCATOR and UKMOs GloSEA5.

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The area where hurricanes form has cooled a fair bit in the last week

cdas-sflux_ssta_eatl_1.thumb.png.b0559c69f41ebd7d873ce441403510d7.png

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As things stand it looks like we are headed for a cold Atlantic full stop. 

cdas-sflux_ssta_global_1.png

Not a bad thing in removing the +NAO tripole somewhat.

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To do a quick update. Atlantic subsurface temps are below average just like the surface ones.

    thetao_in_Met_O_GLO_PHYS_dm_TEM_15330367       thetao_in_Met_O_GLO_PHYS_dm_TEM_15330356  

 

And a cross section by latitude over Atlantic at 20W and 30W for Juney showing that cooler waters are not just near the surface.

Potential_temperature_depth_belo_in_ocnm  Potential_temperature_depth_belo_in_ocnm

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23 minutes ago, Recretos said:

To do a quick update. Atlantic subsurface temps are below average just like the surface ones.

    thetao_in_Met_O_GLO_PHYS_dm_TEM_15330367       thetao_in_Met_O_GLO_PHYS_dm_TEM_15330356  

 

And a cross section by latitude over Atlantic at 20W and 30W for Juney showing that cooler waters are not just near the surface.

Potential_temperature_depth_belo_in_ocnm  Potential_temperature_depth_belo_in_ocnm

Nice charts.

The grey areas on the cross section charts = missing data?

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There's a very interesting research paper recently published (Feb 2019) and they have renamed the North Atlantic 'Cold Blob' as a 'Warming Hole'. The paper titled Impacts of the North Atlantic Warming Hole in Future Climate Projections: Mean Atmospheric Circulation and the North Atlantic jet is behind a paywall, but there is an easy-to-read review of the paper on the Science Daily website here. Some extracts:

The North Atlantic warming hole (NAWH), a region of reduced warming located in the North Atlantic Ocean, significantly affects the North Atlantic jet stream in climate simulations of the future.

Sea surface temperatures (SST) are projected to increase in most of the world's oceans as the result of global climate change. However, within an area of rotating ocean currents just south of Greenland an anomaly exists where colder sea-surface temperatures were documented in both global climate-model projections and in observations.

"It's called a hole because there is a lack of warming. We found that this region of the ocean is a really important place for forcing the jet stream that goes across the North Atlantic Ocean," said Melissa Gervais, assistant professor of meteorology and atmospheric science, Penn State

Development of the NAWH is linked to a slowdown of the Atlantic Meridional Overturning Circulation, a large system of ocean currents that carry warm water from the tropics northwards into the North Atlantic, and is thought to be caused by an influx of fresh water coming from melting Arctic sea ice.

"These changes in SST patterns occur as the result of changes in ocean circulation and could have a significant impact on atmospheric circulation and the North Atlantic storm track in the future. We found that it's really quite important for that region. The NAWH seems to be elongating the jet even further and shifting it a little bit north."

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On 16/04/2019 at 21:24, Blessed Weather said:

There's a very interesting research paper recently published (Feb 2019) and they have renamed the North Atlantic 'Cold Blob' as a 'Warming Hole'. The paper titled Impacts of the North Atlantic Warming Hole in Future Climate Projections: Mean Atmospheric Circulation and the North Atlantic jet is behind a paywall, but there is an easy-to-read review of the paper on the Science Daily website here. Some extracts:

The North Atlantic warming hole (NAWH), a region of reduced warming located in the North Atlantic Ocean, significantly affects the North Atlantic jet stream in climate simulations of the future.

Sea surface temperatures (SST) are projected to increase in most of the world's oceans as the result of global climate change. However, within an area of rotating ocean currents just south of Greenland an anomaly exists where colder sea-surface temperatures were documented in both global climate-model projections and in observations.

"It's called a hole because there is a lack of warming. We found that this region of the ocean is a really important place for forcing the jet stream that goes across the North Atlantic Ocean," said Melissa Gervais, assistant professor of meteorology and atmospheric science, Penn State

Development of the NAWH is linked to a slowdown of the Atlantic Meridional Overturning Circulation, a large system of ocean currents that carry warm water from the tropics northwards into the North Atlantic, and is thought to be caused by an influx of fresh water coming from melting Arctic sea ice.

"These changes in SST patterns occur as the result of changes in ocean circulation and could have a significant impact on atmospheric circulation and the North Atlantic storm track in the future. We found that it's really quite important for that region. The NAWH seems to be elongating the jet even further and shifting it a little bit north."

This sounds like bad news to me as this cold blob/NAWH is likely to make any cold spells even more difficult for us to achieve.

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Posted (edited)
On 16 April 2019 at 21:24, Blessed Weather said:

There's a very interesting research paper recently published (Feb 2019) and they have renamed the North Atlantic 'Cold Blob' as a 'Warming Hole'. The paper titled Impacts of the North Atlantic Warming Hole in Future Climate Projections: Mean Atmospheric Circulation and the North Atlantic jet is behind a paywall, but there is an easy-to-read review of the paper on the Science Daily website here. Some extracts:

The North Atlantic warming hole (NAWH), a region of reduced warming located in the North Atlantic Ocean, significantly affects the North Atlantic jet stream in climate simulations of the future.

Sea surface temperatures (SST) are projected to increase in most of the world's oceans as the result of global climate change. However, within an area of rotating ocean currents just south of Greenland an anomaly exists where colder sea-surface temperatures were documented in both global climate-model projections and in observations.

"It's called a hole because there is a lack of warming. We found that this region of the ocean is a really important place for forcing the jet stream that goes across the North Atlantic Ocean," said Melissa Gervais, assistant professor of meteorology and atmospheric science, Penn State

Development of the NAWH is linked to a slowdown of the Atlantic Meridional Overturning Circulation, a large system of ocean currents that carry warm water from the tropics northwards into the North Atlantic, and is thought to be caused by an influx of fresh water coming from melting Arctic sea ice.

"These changes in SST patterns occur as the result of changes in ocean circulation and could have a significant impact on atmospheric circulation and the North Atlantic storm track in the future. We found that it's really quite important for that region. The NAWH seems to be elongating the jet even further and shifting it a little bit north."

Very interesting,  just read the whole article, well the free bit anyway.  Just a thought on the NAWH from viewing the models over the last few years.  It has been evident on the SST charts for a while now, but as to how it will affect UK weather, here the SST anomaly as at April 2016 and now 2019:

image.thumb.jpg.cd790123eb405cac489791b1bfb46bb7.jpgimage.thumb.jpg.dc04eb4032d52dd5671e64526b76c20b.jpg

If you think of the seasons prior, left chart rubbish winter, rubbish summer; right chart rubbish winter, glorious hot summer (ok yet to be confirmed but pattern similar to last year which was!).

My point is that if there is a slow down in the AMOC aka the Gulf Stream intuitively you might have expected the opposite i.e colder winters and shorter summers for UK, but it actually may be shifting the opposite way?

Edited by Mike Poole

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Posted (edited)

Its a shame that the slowdown won't be enough to stop and reverse the Artic and Antarctic rapid meltdowns.

Edited by Lettucing Gutted

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9 hours ago, karyo said:

This sounds like bad news to me as this cold blob/NAWH is likely to make any cold spells even more difficult for us to achieve.

 

53 minutes ago, Mike Poole said:

(Snipped)

My point is that if there is a slow down in the AMOC aka the Gulf Stream intuitively you might have expected the opposite i.e colder winters and shorter summers for UK, but it actually may be shifting the opposite way?

I agree that taking the research findings on face value your concerns would seem a real possibility. But I wonder if taking one consequence of Arctic Warming (i.e. melting sea ice and warm hole) in isolation will give a reliable indicator about the future behaviour of the Jet Stream? What about another impact of Arctic warming - a reduced temperature gradient between Arctic region and mid latitudes which is thought will reduce the 'fuel' that drives the Jet Stream, causing it to be more prone to meandering with more frequently blocked patterns? And then we have the dramatic change in sea ice in the Barents Sea causing changes to the regional climate in that area, linked with wintertime cyclones moving south into western Europe instead of east into Siberia. This concluding remark from the 2018 article Extreme weather in Europe linked to less sea ice and warming in the Barents Sea:

".....we believe that the 2005 regime shift we observed over the Barents Sea may have contributed to the increasingly frequent extreme weather events experienced over Europe in the past decade or so."

So lots going on thanks to Climate Change and the interactions and consequences are far from nailed IMHO.

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Posted (edited)

 

Edited by knocker

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If the Nino base state takes hold again following the strong WWB in the coming fortnight, the corresponding mean trough position W or WSW of the UK could sustain or even reinforce that SST anomaly pattern..

Those negative anomalies are far enough north that I wonder whether the boost to the Bermuda section of the subtropical ridge will occur further north than is usual for a -AMO. That could limit or negate increases in trade winds, hence wind shear, across the Caribbean.

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