Possible changes in Atlantic Ocean circulation
 

Food for thought

http://www.bbc.co.uk/news/science-en...campaign=bbcne
ws&ocid=socialflow_twitter&ns_mchannel=social&ns_s ource=twitter

It's not the first time that this idea has been put forward but I have
always said that, as our climate is currently anomalously warm for our
latitude, it would be easier for circulation changes to result in
cooling of our bit of the planet than warming.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

Possible changes in Atlantic Ocean circulation
 

On 11/04/18 18:54, Norman Lynagh wrote:
Food for thought

http://www.bbc.co.uk/news/science-en...campaign=bbcne
ws&ocid=socialflow_twitter&ns_mchannel=social&ns_s ource=twitter

It's not the first time that this idea has been put forward but I have
always said that, as our climate is currently anomalously warm for our
latitude, it would be easier for circulation changes to result in
cooling of our bit of the planet than warming.


Yes, it was almost fifty years ago when I first read about sudden
changes in the N Atlantic current circulation and consequent changes in
climate. I think the book in which I read it was published in the early
60s. Of course, at that time they didn't know the cause of the bi-stable
nature of the current system. I'm not entirely sure they've got it right
even now.

--
Graham P Davis, Bracknell, Berks. Web-site: http://www.scarlet-jade.com/
"There is nothing more frustrating than playing hide and seek with a
deaf wolf." [Benton Fraser]
OS: Linux [openSUSE Tumbleweed]

Possible changes in Atlantic Ocean circulation
 

On Wednesday, April 11, 2018 at 8:13:49 PM UTC+1, Graham P Davis wrote:
On 11/04/18 18:54, Norman Lynagh wrote:
Food for thought

http://www.bbc.co.uk/news/science-en...campaign=bbcne
ws&ocid=socialflow_twitter&ns_mchannel=social&ns_s ource=twitter

It's not the first time that this idea has been put forward but I have
always said that, as our climate is currently anomalously warm for our
latitude, it would be easier for circulation changes to result in
cooling of our bit of the planet than warming.


Yes, it was almost fifty years ago when I first read about sudden
changes in the N Atlantic current circulation and consequent changes in
climate. I think the book in which I read it was published in the early
60s. Of course, at that time they didn't know the cause of the bi-stable
nature of the current system. I'm not entirely sure they've got it right
even now.

--
Graham P Davis, Bracknell, Berks. Web-site: http://www.scarlet-jade.com/

Well, time will tell.

On a similar subject, that longstanding cold pool in the Atlantic seems less evident. At least going by this http://www.emc.ncep.noaa.gov/researc...s/wkanomv2.png
Also the despite the very cold March the SST in the SW Approaches is near normal, 10-11C @ Sevenstones. Mind you, that certainly can't be said for the North Sea.

Also, there was a very cold May/June in 1972 (I think that was the year) The wind was generally W - SW in June. Dominated by a returning Polar Maritime I would assume. (I was a geography student at Middlesex Poly at the time)

Do you have anything on the SST anomalies / circulation patterns that year? I know icebergs were blamed, but that sounds a bit simplistic to me.

Graham
Penzance

Possible changes in Atlantic Ocean circulation
 

On 11/04/18 20:40, Graham Easterling wrote:
On Wednesday, April 11, 2018 at 8:13:49 PM UTC+1, Graham P Davis
wrote:
On 11/04/18 18:54, Norman Lynagh wrote:
Food for thought

http://www.bbc.co.uk/news/science-en...campaign=bbcne




ws&ocid=socialflow_twitter&ns_mchannel=social&ns_s ource=twitter

It's not the first time that this idea has been put forward but I
have always said that, as our climate is currently anomalously
warm for our latitude, it would be easier for circulation changes
to result in cooling of our bit of the planet than warming.


Yes, it was almost fifty years ago when I first read about sudden
changes in the N Atlantic current circulation and consequent
changes in climate. I think the book in which I read it was
published in the early 60s. Of course, at that time they didn't
know the cause of the bi-stable nature of the current system. I'm
not entirely sure they've got it right even now.


Well, time will tell.

On a similar subject, that longstanding cold pool in the Atlantic
seems less evident. At least going by this
http://www.emc.ncep.noaa.gov/researc...s/wkanomv2.png


Also the despite the very cold March the SST in the SW Approaches is
near normal, 10-11C @ Sevenstones. Mind you, that certainly can't be
said for the North Sea.

Also, there was a very cold May/June in 1972 (I think that was the
year) The wind was generally W - SW in June. Dominated by a returning
Polar Maritime I would assume. (I was a geography student at
Middlesex Poly at the time)

Do you have anything on the SST anomalies / circulation patterns that
year? I know icebergs were blamed, but that sounds a bit simplistic
to me.

The pressure anomalies for those months were as follows:
May: A low of -8hPa south of Iceland and west of Scotland. A trough
extended across southern Scotland towards Turkey. Another trough
extended to S Greenland and then NW to north of Baffin Bay. A strong WNW
flow ran from the Labrador Sea to SW England.
June: The low anomaly moved north to be just off SE Iceland with centre
of about -12hPa. A -2hPa contour ran from the Brest peninsula to the
southern tip of Greenland and thence along the NE coast of Baffin I.

I recall it being 1970 when a cold July was blamed on record icebergs by
people who should have known better (Lamb, Ratcliffe, Murray) but
pressure anomalies for the preceding winter don't match my memory so I
may have got two events mixed. However, it could also be that the
anomalies calculated now are totally different from what I remember
because the normals were for different periods; those I remember would
have been against 1931-60 normals. A thirty-year normal has been the
accepted length for comparison purposes for weather forecasts but is
totally useless for climatological use and a much longer period should
be used. One reason I prefer GISS 1951-80 temperature normal is that you
could relabel it 1901-2000 and not be far out. ;-)

The SST anomaly for the occasion I remember - whatever year it was - was
that there was a belt of very cold water from Labrador to Ireland with a
-2C anomaly across the middle of that area. This cold water was blamed
for the cold weather but the stupid suggestion was made that it was due
to the melting of a record number of icebergs off the Grand Banks. I
pointed out that the anomaly had formed before the bergs could have
melted and even if that point was ignored and all the bergs had suddenly
melted, that could only have caused a twentieth of the intensity of the
observed anomaly.

I got the monthly pressure anomalies from
http://iridl.ldeo.columbia.edu/maproom/ but their SST anomalies only goo
back to 1981.

--
Graham P Davis, Bracknell, Berks. Web-site: http://www.scarlet-jade.com/
"There is nothing more frustrating than playing hide and seek with a
deaf wolf." [Benton Fraser]
OS: Linux [openSUSE Tumbleweed]

Possible changes in Atlantic Ocean circulation
 

On Thursday, April 12, 2018 at 10:34:22 AM UTC+1, Graham P Davis wrote:
On 11/04/18 20:40, Graham Easterling wrote:
On Wednesday, April 11, 2018 at 8:13:49 PM UTC+1, Graham P Davis
wrote:
On 11/04/18 18:54, Norman Lynagh wrote:
Food for thought

http://www.bbc.co.uk/news/science-en...campaign=bbcne




ws&ocid=socialflow_twitter&ns_mchannel=social&ns_s ource=twitter

It's not the first time that this idea has been put forward but I
have always said that, as our climate is currently anomalously
warm for our latitude, it would be easier for circulation changes
to result in cooling of our bit of the planet than warming.


Yes, it was almost fifty years ago when I first read about sudden
changes in the N Atlantic current circulation and consequent
changes in climate. I think the book in which I read it was
published in the early 60s. Of course, at that time they didn't
know the cause of the bi-stable nature of the current system. I'm
not entirely sure they've got it right even now.


Well, time will tell.

On a similar subject, that longstanding cold pool in the Atlantic
seems less evident. At least going by this
http://www.emc.ncep.noaa.gov/researc...s/wkanomv2.png


Also the despite the very cold March the SST in the SW Approaches is
near normal, 10-11C @ Sevenstones. Mind you, that certainly can't be
said for the North Sea.

Also, there was a very cold May/June in 1972 (I think that was the
year) The wind was generally W - SW in June. Dominated by a returning
Polar Maritime I would assume. (I was a geography student at
Middlesex Poly at the time)

Do you have anything on the SST anomalies / circulation patterns that
year? I know icebergs were blamed, but that sounds a bit simplistic
to me.

The pressure anomalies for those months were as follows:
May: A low of -8hPa south of Iceland and west of Scotland. A trough
extended across southern Scotland towards Turkey. Another trough
extended to S Greenland and then NW to north of Baffin Bay. A strong WNW
flow ran from the Labrador Sea to SW England.
June: The low anomaly moved north to be just off SE Iceland with centre
of about -12hPa. A -2hPa contour ran from the Brest peninsula to the
southern tip of Greenland and thence along the NE coast of Baffin I.

I recall it being 1970 when a cold July was blamed on record icebergs by
people who should have known better (Lamb, Ratcliffe, Murray) but
pressure anomalies for the preceding winter don't match my memory so I
may have got two events mixed. However, it could also be that the
anomalies calculated now are totally different from what I remember
because the normals were for different periods; those I remember would
have been against 1931-60 normals. A thirty-year normal has been the
accepted length for comparison purposes for weather forecasts but is
totally useless for climatological use and a much longer period should
be used. One reason I prefer GISS 1951-80 temperature normal is that you
could relabel it 1901-2000 and not be far out. ;-)

The SST anomaly for the occasion I remember - whatever year it was - was
that there was a belt of very cold water from Labrador to Ireland with a
-2C anomaly across the middle of that area. This cold water was blamed
for the cold weather but the stupid suggestion was made that it was due
to the melting of a record number of icebergs off the Grand Banks. I
pointed out that the anomaly had formed before the bergs could have
melted and even if that point was ignored and all the bergs had suddenly
melted, that could only have caused a twentieth of the intensity of the
observed anomaly.

I got the monthly pressure anomalies from
http://iridl.ldeo.columbia.edu/maproom/ but their SST anomalies only goo
back to 1981.

--
Graham P Davis, Bracknell, Berks. Web-site: http://www.scarlet-jade.com/
"There is nothing more frustrating than playing hide and seek with a
deaf wolf." [Benton Fraser]
OS: Linux [openSUSE Tumbleweed]

Thanks for all that.

I think it was 1972, as I started at Middlesex Poly in Sept '70, and it was whilst I was there.

There's a few things I remember about that June. Even in London it was often quite chilly & showery. For much of June only the Thames valley seemed to get above 15C, even though the wind was was typically from the west. I remember it being commented on that the cold June was very unusual, as it was not a northerly month. Based on the weather type, the westerly winds were predominantly returning Pm. Backed up by what you say above.

Even in July, when I was back in Cornwall, working on the farm, the weather was ridiculously cool for July, and there was so much mist & drizzle, probably enhanced by the wind crossing the area of the low SST. I seem to remember that summer finally arrived in August - though I might be getting confused about that.

Graham
Penzance

Possible changes in Atlantic Ocean circulation
 

On Thursday, April 12, 2018 at 3:16:57 PM UTC+1, Graham Easterling wrote:
On Thursday, April 12, 2018 at 10:34:22 AM UTC+1, Graham P Davis wrote:
On 11/04/18 20:40, Graham Easterling wrote:
On Wednesday, April 11, 2018 at 8:13:49 PM UTC+1, Graham P Davis
wrote:
On 11/04/18 18:54, Norman Lynagh wrote:
Food for thought

http://www.bbc.co.uk/news/science-en...campaign=bbcne




ws&ocid=socialflow_twitter&ns_mchannel=social&ns_s ource=twitter

It's not the first time that this idea has been put forward but I
have always said that, as our climate is currently anomalously
warm for our latitude, it would be easier for circulation changes
to result in cooling of our bit of the planet than warming.


Yes, it was almost fifty years ago when I first read about sudden
changes in the N Atlantic current circulation and consequent
changes in climate. I think the book in which I read it was
published in the early 60s. Of course, at that time they didn't
know the cause of the bi-stable nature of the current system. I'm
not entirely sure they've got it right even now.


Well, time will tell.

On a similar subject, that longstanding cold pool in the Atlantic
seems less evident. At least going by this
http://www.emc.ncep.noaa.gov/researc...s/wkanomv2.png


Also the despite the very cold March the SST in the SW Approaches is
near normal, 10-11C @ Sevenstones. Mind you, that certainly can't be
said for the North Sea.

Also, there was a very cold May/June in 1972 (I think that was the
year) The wind was generally W - SW in June. Dominated by a returning
Polar Maritime I would assume. (I was a geography student at
Middlesex Poly at the time)

Do you have anything on the SST anomalies / circulation patterns that
year? I know icebergs were blamed, but that sounds a bit simplistic
to me.

The pressure anomalies for those months were as follows:
May: A low of -8hPa south of Iceland and west of Scotland. A trough
extended across southern Scotland towards Turkey. Another trough
extended to S Greenland and then NW to north of Baffin Bay. A strong WNW
flow ran from the Labrador Sea to SW England.
June: The low anomaly moved north to be just off SE Iceland with centre
of about -12hPa. A -2hPa contour ran from the Brest peninsula to the
southern tip of Greenland and thence along the NE coast of Baffin I.

I recall it being 1970 when a cold July was blamed on record icebergs by
people who should have known better (Lamb, Ratcliffe, Murray) but
pressure anomalies for the preceding winter don't match my memory so I
may have got two events mixed. However, it could also be that the
anomalies calculated now are totally different from what I remember
because the normals were for different periods; those I remember would
have been against 1931-60 normals. A thirty-year normal has been the
accepted length for comparison purposes for weather forecasts but is
totally useless for climatological use and a much longer period should
be used. One reason I prefer GISS 1951-80 temperature normal is that you
could relabel it 1901-2000 and not be far out. ;-)

The SST anomaly for the occasion I remember - whatever year it was - was
that there was a belt of very cold water from Labrador to Ireland with a
-2C anomaly across the middle of that area. This cold water was blamed
for the cold weather but the stupid suggestion was made that it was due
to the melting of a record number of icebergs off the Grand Banks. I
pointed out that the anomaly had formed before the bergs could have
melted and even if that point was ignored and all the bergs had suddenly
melted, that could only have caused a twentieth of the intensity of the
observed anomaly.

I got the monthly pressure anomalies from
http://iridl.ldeo.columbia.edu/maproom/ but their SST anomalies only goo
back to 1981.

--
Graham P Davis, Bracknell, Berks. Web-site: http://www.scarlet-jade.com/
"There is nothing more frustrating than playing hide and seek with a
deaf wolf." [Benton Fraser]
OS: Linux [openSUSE Tumbleweed]

Thanks for all that.

I think it was 1972, as I started at Middlesex Poly in Sept '70, and it was whilst I was there.

There's a few things I remember about that June. Even in London it was often quite chilly & showery. For much of June only the Thames valley seemed to get above 15C, even though the wind was was typically from the west. I remember it being commented on that the cold June was very unusual, as it was not a northerly month. Based on the weather type, the westerly winds were predominantly returning Pm. Backed up by what you say above.

Even in July, when I was back in Cornwall, working on the farm, the weather was ridiculously cool for July, and there was so much mist & drizzle, probably enhanced by the wind crossing the area of the low SST. I seem to remember that summer finally arrived in August - though I might be getting confused about that.

Graham
Penzance

The Met Office Monthly Weather Report of June 1972 confirms it was an exceptionally cold month, with many long-standing weather stations having their coldest June on record, e.g. Falmouth since 1869, Manchester & Ross-on-Wye since 1886, Bournemouth since 1905 and Teignmouth since 1910. The highest temperature recorded anywhere in England & wales was 23.0C, and believed to be the lowest absolute maxima since at least 1884.

Dick Lovett

Possible changes in Atlantic Ocean circulation
 

On Thursday, April 12, 2018 at 4:53:27 PM UTC+1, wrote:
On Thursday, April 12, 2018 at 3:16:57 PM UTC+1, Graham Easterling wrote:
On Thursday, April 12, 2018 at 10:34:22 AM UTC+1, Graham P Davis wrote:
On 11/04/18 20:40, Graham Easterling wrote:
On Wednesday, April 11, 2018 at 8:13:49 PM UTC+1, Graham P Davis
wrote:
On 11/04/18 18:54, Norman Lynagh wrote:
Food for thought

http://www.bbc.co.uk/news/science-en...campaign=bbcne




ws&ocid=socialflow_twitter&ns_mchannel=social&ns_s ource=twitter

It's not the first time that this idea has been put forward but I
have always said that, as our climate is currently anomalously
warm for our latitude, it would be easier for circulation changes
to result in cooling of our bit of the planet than warming.


Yes, it was almost fifty years ago when I first read about sudden
changes in the N Atlantic current circulation and consequent
changes in climate. I think the book in which I read it was
published in the early 60s. Of course, at that time they didn't
know the cause of the bi-stable nature of the current system. I'm
not entirely sure they've got it right even now.


Well, time will tell.

On a similar subject, that longstanding cold pool in the Atlantic
seems less evident. At least going by this
http://www.emc.ncep.noaa.gov/researc...s/wkanomv2.png


Also the despite the very cold March the SST in the SW Approaches is
near normal, 10-11C @ Sevenstones. Mind you, that certainly can't be
said for the North Sea.

Also, there was a very cold May/June in 1972 (I think that was the
year) The wind was generally W - SW in June. Dominated by a returning
Polar Maritime I would assume. (I was a geography student at
Middlesex Poly at the time)

Do you have anything on the SST anomalies / circulation patterns that
year? I know icebergs were blamed, but that sounds a bit simplistic
to me.

The pressure anomalies for those months were as follows:
May: A low of -8hPa south of Iceland and west of Scotland. A trough
extended across southern Scotland towards Turkey. Another trough
extended to S Greenland and then NW to north of Baffin Bay. A strong WNW
flow ran from the Labrador Sea to SW England.
June: The low anomaly moved north to be just off SE Iceland with centre
of about -12hPa. A -2hPa contour ran from the Brest peninsula to the
southern tip of Greenland and thence along the NE coast of Baffin I.

I recall it being 1970 when a cold July was blamed on record icebergs by
people who should have known better (Lamb, Ratcliffe, Murray) but
pressure anomalies for the preceding winter don't match my memory so I
may have got two events mixed. However, it could also be that the
anomalies calculated now are totally different from what I remember
because the normals were for different periods; those I remember would
have been against 1931-60 normals. A thirty-year normal has been the
accepted length for comparison purposes for weather forecasts but is
totally useless for climatological use and a much longer period should
be used. One reason I prefer GISS 1951-80 temperature normal is that you
could relabel it 1901-2000 and not be far out. ;-)

The SST anomaly for the occasion I remember - whatever year it was - was
that there was a belt of very cold water from Labrador to Ireland with a
-2C anomaly across the middle of that area. This cold water was blamed
for the cold weather but the stupid suggestion was made that it was due
to the melting of a record number of icebergs off the Grand Banks. I
pointed out that the anomaly had formed before the bergs could have
melted and even if that point was ignored and all the bergs had suddenly
melted, that could only have caused a twentieth of the intensity of the
observed anomaly.

I got the monthly pressure anomalies from
http://iridl.ldeo.columbia.edu/maproom/ but their SST anomalies only goo
back to 1981.

--
Graham P Davis, Bracknell, Berks. Web-site: http://www.scarlet-jade.com/
"There is nothing more frustrating than playing hide and seek with a
deaf wolf." [Benton Fraser]
OS: Linux [openSUSE Tumbleweed]

Thanks for all that.

I think it was 1972, as I started at Middlesex Poly in Sept '70, and it was whilst I was there.

There's a few things I remember about that June. Even in London it was often quite chilly & showery. For much of June only the Thames valley seemed to get above 15C, even though the wind was was typically from the west. I remember it being commented on that the cold June was very unusual, as it was not a northerly month. Based on the weather type, the westerly winds were predominantly returning Pm. Backed up by what you say above.

Even in July, when I was back in Cornwall, working on the farm, the weather was ridiculously cool for July, and there was so much mist & drizzle, probably enhanced by the wind crossing the area of the low SST. I seem to remember that summer finally arrived in August - though I might be getting confused about that.

Graham
Penzance

The Met Office Monthly Weather Report of June 1972 confirms it was an exceptionally cold month, with many long-standing weather stations having their coldest June on record, e.g. Falmouth since 1869, Manchester & Ross-on-Wye since 1886, Bournemouth since 1905 and Teignmouth since 1910. The highest temperature recorded anywhere in England & wales was 23.0C, and believed to be the lowest absolute maxima since at least 1884.

Dick Lovett

Interesting - thanks.

Graham
Penzance

Possible changes in Atlantic Ocean circulation
 

On 11/04/2018 18:54, Norman Lynagh wrote:
Food for thought

Norman, I have been led to believe that the Gulf Stream/North Atlantic
Drift is wind driven?

I have attended many lectures and a few conferences that have stated to
the above. Which is right?

--
Nick Gardner
Otter Valley, Devon
20 m amsl
http://www.ottervalleyweather.me.uk

Possible changes in Atlantic Ocean circulation
 

On Thursday, April 12, 2018 at 7:58:23 PM UTC+1, Nick Gardner wrote:
On 11/04/2018 18:54, Norman Lynagh wrote:
Food for thought

Norman, I have been led to believe that the Gulf Stream/North Atlantic
Drift is wind driven?

I have attended many lectures and a few conferences that have stated to
the above. Which is right?

--
Nick Gardner
Otter Valley, Devon
20 m amsl
http://www.ottervalleyweather.me.uk

Also, don't forget the coriolis effect.

Graham
Penzance

Possible changes in Atlantic Ocean circulation
 

On 12/04/18 19:58, Nick Gardner wrote:
On 11/04/2018 18:54, Norman Lynagh wrote:
Food for thought

Norman, I have been led to believe that the Gulf Stream/North Atlantic
Drift is wind driven?

I have attended many lectures and a few conferences that have stated to
the above. Which is right?


I think the answer is yes and no. The circulation is partially
wind-driven; an explanation given fifty-odd years ago for any sudden
switch-off of the NAD in the past was a weakening of the subtropical
high, although the author was clutching at straws to explain this
bi-stable nature of the circulation.

The Gulf Stream is mainly a density current. Along the eastern seaboard
of the USA, the warm water of the Gulf Stream is of a lower density to
the cold, inshore water fed by the Labrador Current. The surface of the
warm water is higher than the cold and water flows from high water level
to low. As happens when air flows from surface high pressure to low, the
Coriolis effect results in the water flowing roughly parallel to the SST
isotherms.

Although the NAD has disappeared in the past at times, any talk of the
Gulf Stream itself shutting down can be dismissed; I reckon it would
take the Earth to stop spinning for that to happen. In any case,
evidence from Sargassum weed shows that the clockwise circulation of
warm water has continued for at least 30,000 years.

--
Graham P Davis, Bracknell, Berks. Web-site: http://www.scarlet-jade.com/
"There is nothing more frustrating than playing hide and seek with a
deaf wolf." [Benton Fraser]
OS: Linux [openSUSE Tumbleweed]