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Post by missouriboy on Sept 21, 2021 2:30:17 GMT
Causes and effects of the AMO have been discussed many times of this and the previous site. Many drivers have been proposed. Here is another from a paper published in 1988, entitled: "the Great Salinity Anomaly" www.sciencedirect.com/science/article/abs/pii/0079661188900493 . The hypothesis is that periodic pulses of cold arctic water are pushed out of the Arctic Ocean into the North Atlantic by changes in wind direction from the dominant high, clockwise circulation to a counter-clockwise low pressure circulation. These cold water pulses ultimately cool most of the AMO area (north of 25N latitude I believe). Our 170-year AMO timeseries shows three warm cycles with two cooler cycles in between. Electroverse also had a writeup on this some time back: electroverse.net/the-arctics-ticking-climate-bomb-little-ice-age-imminent/.
I have been collecting data on the Greenland Blocking Index for some time. The GBI is the mean 500 hPa geopotential height for the 60-80°N, 20-80°W region. It measures blocking over Greenland. The following two charts show seasonal and annual GBI in relation to the AMO. There seems to be a reasonable correlation between the two. When GBI pressure is low for a long period of time the AMO cools. When GBI is high, the AMO warms. Lower pressure over Greenland might be conducive to counter-clockwise flow over the Arctic Ocean.
We know this occurs, and have detailed records of a relatively recent event: during the 1960s and 1970s, a surge of fresh Arctic water was released that cooled the top half-mile of parts of the North Atlantic. Known as the Great Salinity Anomaly, British oceanographer Robert R. Dickson said the event represented one of the most persistent and extreme variations in global ocean climate observed during the past century. The surge of ice and freshwater cooled Northern Europe dramatically and disrupted the North Atlantic food chain. Between 1951 and 2010, many of Europe’s exceptionally cold winters occurred during the period of the Great Salinity Anomaly. (Electroverse)
We see that the GBI has become extremely variable in the last decade. The record high of 2010 was immediately followed by downturns. The AMO has not begun cooling yet. But it takes a while to cool that portion of the N Atlantic between 25N & 45N, but the part seems to be coming down slowly. We have already seen the decline from 2015 north of 45N. You will note that the GBI and AMO declines of the 60s and 70s were coincident with low solar cycle 20, which might suggest a solar connection to declining pressure over Greenland, and coincident export of cold arctic waters into the North Atlantic.
Comments? Suggestions? Naut! Where are you?
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Post by glennkoks on Sept 21, 2021 12:37:19 GMT
I have not had a lot of time to research it yet but it has been theorized that atmospheric circulation changes have an effect on dust and low cloud feedbacks that are strong enough to effect the SST's in the Atlantic. Over the last few years more and more has been made about Saharan dust traveling across the Atlantic. It has a very suppressive effect on the Atlantic Hurricane season. Hurricanes have a cooling effect on the tropics and are one of the ways the heat from the tropics is re-distributed north. As with most things climate related the feedbacks are complex. Changes in atmospheric circulation patterns release colder fresh water locked up in the North Atlantic sending it southward effectively disrupting the "normal" patterns. It is quite conceivable this has an effect on precipitation patterns over the Sahara. A greening of the Sahara probably means less dust transported across the Atlantic which would lead to more clouds and hurricanes which have a huge effect on how heat is re-distributed. The more I study the climate the less I understand about how it functions. There are so many complex patterns and feedbacks each of which have an effect on our global temperature which is never stable. Which is why I have become more and more skeptical of those who seek to simplify our climate to just CO2. It is just much, much more complex than that. It stands to reason that the single biggest factor effecting our climate is not CO2 but a variable star we are all rotating around. The following link is to a study demonstrating how low clouds and dust amplify SST changes in the Atlantic. pubmed.ncbi.nlm.nih.gov/32818003/ |
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Post by duwayne on Sept 21, 2021 16:27:55 GMT
Causes and effects of the AMO have been discussed many times of this and the previous site. Many drivers have been proposed. Here is another from a paper published in 1988, entitled: "the Great Salinity Anomaly" www.sciencedirect.com/science/article/abs/pii/0079661188900493 . The hypothesis is that periodic pulses of cold arctic water are pushed out of the Arctic Ocean into the North Atlantic by changes in wind direction from the dominant high, clockwise circulation to a counter-clockwise low pressure circulation. These cold water pulses ultimately cool most of the AMO area (north of 25N latitude I believe). Our 170-year AMO timeseries shows three warm cycles with two cooler cycles in between. Electroverse also had a writeup on this some time back: electroverse.net/the-arctics-ticking-climate-bomb-little-ice-age-imminent/.
I have been collecting data on the Greenland Blocking Index for some time. The GBI is the mean 500 hPa geopotential height for the 60-80°N, 20-80°W region. It measures blocking over Greenland. The following two charts show seasonal and annual GBI in relation to the AMO. There seems to be a reasonable correlation between the two. When GBI pressure is low for a long period of time the AMO cools. When GBI is high, the AMO warms. Lower pressure over Greenland might be conducive to counter-clockwise flow over the Arctic Ocean.
We know this occurs, and have detailed records of a relatively recent event: during the 1960s and 1970s, a surge of fresh Arctic water was released that cooled the top half-mile of parts of the North Atlantic. Known as the Great Salinity Anomaly, British oceanographer Robert R. Dickson said the event represented one of the most persistent and extreme variations in global ocean climate observed during the past century. The surge of ice and freshwater cooled Northern Europe dramatically and disrupted the North Atlantic food chain. Between 1951 and 2010, many of Europe’s exceptionally cold winters occurred during the period of the Great Salinity Anomaly. (Electroverse)
We see that the GBI has become extremely variable in the last decade. The record high of 2010 was immediately followed by downturns. The AMO has not begun cooling yet. But it takes a while to cool that portion of the N Atlantic between 25N & 45N, but the part seems to be coming down slowly. We have already seen the decline from 2015 north of 45N. You will note that the GBI and AMO declines of the 60s and 70s were coincident with low solar cycle 20, which might suggest a solar connection to declining pressure over Greenland, and coincident export of cold arctic waters into the North Atlantic.
Comments? Suggestions? Naut! Where are you?
Missouri, the correlation between GBI and AMO looks good a lot of the time, but around 1977 and again around 2007, they went their separate ways for several years. Have you calculated an "R-squared" for the 2 series? It's very easy to do if you have the information on an Excel Spreadsheet. For example, if you have the data for the 2 series in column A and B and they start with Row 1 and end in Row 100 the formula for R Squared is =RSQ(A1:A100,B1:B100)
Also, do you know if the GBI is detrended?
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Post by missouriboy on Sept 21, 2021 16:55:08 GMT
I have not had a lot of time to research it yet but it has been theorized that atmospheric circulation changes have an effect on dust and low cloud feedbacks that are strong enough to effect the SST's in the Atlantic. Over the last few years more and more has been made about Saharan dust traveling across the Atlantic. It has a very suppressive effect on the Atlantic Hurricane season. Hurricanes have a cooling effect on the tropics and are one of the ways the heat from the tropics is re-distributed north. As with most things climate related the feedbacks are complex. Changes in atmospheric circulation patterns release colder fresh water locked up in the North Atlantic sending it southward effectively disrupting the "normal" patterns. It is quite conceivable this has an effect on precipitation patterns over the Sahara. A greening of the Sahara probably means less dust transported across the Atlantic which would lead to more clouds and hurricanes which have a huge effect on how heat is re-distributed. The more I study the climate the less I understand about how it functions. There are so many complex patterns and feedbacks each of which have an effect on our global temperature which is never stable. Which is why I have become more and more skeptical of those who seek to simplify our climate to just CO2. It is just much, much more complex than that. It stands to reason that the single biggest factor effecting our climate is not CO2 but a variable star we are all rotating around. The following link is to a study demonstrating how low clouds and dust amplify SST changes in the Atlantic. pubmed.ncbi.nlm.nih.gov/32818003/Totally agree. But there are a hierarchy of forces that can be ranked by probability. Our only dominant "given" is our variable star, the solar forces (radiation, gravity, etc.), which absolutely overwhelm the many planetary forces that effect our climate(s). Even our "given" has changes (such as solar cycles, ) which, in their turn, overwhelm the planetary forces (not to discount other forces which even affect our star). The AGW crowd wish to raise CO2 to the pantheon of planetary forces that direct traffic on our planet. Or even to the level of the sun itself. Science is left with figuring out how "select" solar outputs (inputs here), which are concentrated at the equator (and move with the seasons) are modified and redistributed through our hydrosphere and atmosphere. Not to exclude forces that affect the lithosphere itself. We have bested the ancients in our observation technology and raising models to be the tools of the high priests. But many of the priests are still timeshare salesmen. The honest climate scientist is still left with task of identifying and parameterizing , or eliminating, the "forces" that effect our "climates", while still making a living.  Those who sell their souls in the process have no personal honor. We all postulate ... and then pontificate on our postulations. |
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Post by nonentropic on Sept 21, 2021 18:55:02 GMT
Interestingly a news comment no link, but Ratty will sort, in relation to the fires last year in Australia they claim that the down wind nutrient released over the oceans will have stimulated plankton growth and the consequential CO2 sequestration such that more was removed than initially liberated.
I have as a consequence a belief that fire fighting and forest planting are probably a CO2 elevator.
The fish population love it and Australia can claim CO2 credits and the population should demand more burning to offset Gas usage etc.
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Post by missouriboy on Sept 22, 2021 18:14:09 GMT
Missouri, the correlation between GBI and AMO looks good a lot of the time, but around 1977 and again around 2007, they went their separate ways for several years. Have you calculated an "R-squared" for the 2 series? It's very easy to do if you have the information on an Excel Spreadsheet. For example, if you have the data for the 2 series in column A and B and they start with Row 1 and end in Row 100 the formula for R Squared is =RSQ(A1:A100,B1:B100)
Also, do you know if the GBI is detrended?
The GBI is the mean 500 hPa geopotential height for the 60-80°N, 20-80°W region. It measures blocking over Greenland. psl.noaa.gov/data/timeseries/daily/GBI/ It is published by day and can range from from 4700 to 5300. I have summed these by month and normalized them by month across the timeseries from 1948. While the general trends looks good visually, a year-to-year R-square value is not particularly large at ~0.14. This does not surprise me given the likely complexity of any relationship. In comparison, a month-to-month correlation of ENSO-ONI values to UAH Lower Troposphere tropical temperature anomalies yields an R-square value of 0.23 when UAH is lagged by 3 months. I did not run a month-month comparison for GBI and AMO. A few other observations: GBI is highest in Winter and lowest in summer. Iceland surface pressure appears strongly related to the GBI. Not surprising given its geograohic proximity. GBI tends to peak in the runup to a new solar cycle and decline on the backside. It has also been highest in the weaker cycles. The 2010-11 period was higher than any other period since 1940, and 2021 was higher than 2010-11. Higher pressure over Greenland-Iceland coupled with lower pressure over the Azores and Gibraltar generally result in a negative NAO. I found another article summarizing a long-term study of Arctic Ocean discharges to the North Atlantic between 1945 and 2012. They developed an index ... the AOO. www.us-ocb.org/wp-content/uploads/sites/43/2017/03/OCB-meeting-2014-Beaufort_Gyre_Dynamics_and_implications_for_North_Atlantic-Arctic-exchange-1_189964.pdfThis appears to be the basis for statements that periodic cold-water discharges that were frequent (5-7 years) in the past, had ceased since 1996. No updates found for years after 1996. Thus unknown if the cooling of the N Atlantic observed in 2015-16 (and continuing?) was a re-imergence of this phenomena. The chart below displays the GBI and AOO with reference to solar cycles. There seems to be a shift in the AOO (Arctic discharge events - negative) in relation to the GBI, with a negative AOO in the 60s being associated with a positive GBI ... and opposite in the 70s ... with a shift to negative AOO being associated with a negative GBI in the 90s and a positive-positive combo in the early 2000s. For what it's worth, 1977 and 2007 appear to be on the cusp of a shift in direction.  |
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Post by missouriboy on May 29, 2022 0:38:55 GMT
I'll see y'all from the other side of the AMO.
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Post by code on Jul 26, 2023 14:30:31 GMT
NatureWarning of a forthcoming collapse of the Atlantic meridional overturning circulation Published: 25 July 2023
www.nature.com/articles/s41467-023-39810-w
Abstract"The Atlantic meridional overturning circulation (AMOC) is a major tipping element in the climate system and a future collapse would have severe impacts on the climate in the North Atlantic region. In recent years weakening in circulation has been reported, but assessments by the Intergovernmental Panel on Climate Change (IPCC), based on the Climate Model Intercomparison Project (CMIP) model simulations suggest that a full collapse is unlikely within the 21st century. Tipping to an undesired state in the climate is, however, a growing concern with increasing greenhouse gas concentrations. Predictions based on observations rely on detecting early-warning signals, primarily an increase in variance (loss of resilience) and increased autocorrelation (critical slowing down), which have recently been reported for the AMOC. Here we provide statistical significance and data-driven estimators for the time of tipping. We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions."
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Post by missouriboy on Jul 26, 2023 22:12:19 GMT
There will be wails from Wales. NatureWarning of a forthcoming collapse of the Atlantic meridional overturning circulation Published: 25 July 2023
www.nature.com/articles/s41467-023-39810-w
Abstract"The Atlantic meridional overturning circulation (AMOC) is a major tipping element in the climate system and a future collapse would have severe impacts on the climate in the North Atlantic region. In recent years weakening in circulation has been reported, but assessments by the Intergovernmental Panel on Climate Change (IPCC), based on the Climate Model Intercomparison Project (CMIP) model simulations suggest that a full collapse is unlikely within the 21st century. Tipping to an undesired state in the climate is, however, a growing concern with increasing greenhouse gas concentrations. Predictions based on observations rely on detecting early-warning signals, primarily an increase in variance (loss of resilience) and increased autocorrelation (critical slowing down), which have recently been reported for the AMOC. Here we provide statistical significance and data-driven estimators for the time of tipping. We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions." |
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Post by phydeaux2363 on Jul 26, 2023 22:45:37 GMT
"We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions." Always 30 years from now. Who will remember? Who on this board will be around in 30 years
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Post by acidohm on Jul 27, 2023 4:29:35 GMT
"We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions." Always 30 years from now. Who will remember? Who on this board will be around in 30 years Me, probably.. |
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Post by nonentropic on Jul 27, 2023 5:50:21 GMT
Not that different from the expected reversal of the AMO. which is disappointingly late.
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Post by gridley on Jul 27, 2023 12:33:40 GMT
"We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions." Always 30 years from now. Who will remember? Who on this board will be around in 30 years I might, if I haven't been shot by the Thought Police. |
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Post by phydeaux2363 on Jul 27, 2023 14:47:59 GMT
"We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions." Always 30 years from now. Who will remember? Who on this board will be around in 30 years Me, probably.. I'm glad to hear it, Mr. Acid. See if you can reach me in the grave and let me know if this prediction pans out. My personal belief is a lot of this admittedly anomalous weather is a result of Hunga Tonga eruption. Someone on another thread here linked to Ryan Maue's WUWT post about how the initial estimates of H2O injected in the Stratosphere were off by a lot, and the thinking is now that this eruption could effect weather for years. And, the timing is right. |
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Post by blustnmtn on Jul 27, 2023 16:57:33 GMT
I'm glad to hear it, Mr. Acid. See if you can reach me in the grave and let me know if this prediction pans out. My personal belief is a lot of this admittedly anomalous weather is a result of Hunga Tonga eruption. Someone on another thread here linked to Ryan Maue's WUWT post about how the initial estimates of H2O injected in the Stratosphere were off by a lot, and the thinking is now that this eruption could effect weather for years. And, the timing is right. |
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Those who sell their souls in the process have no personal honor.
