Sea Surface Temperature And Sea Ice Trends(2)

[Ross B]

The other one was getting a little long so please continue discussion here

[The Enforcer]

What has not been successfully demonstrated yet is the response (particulalry in terms of the NAO signal) of warm anomalies over less warm anomalies. This is due to this being quiet a recent phenomenon, witnessed over the last 15 years:

compare 1980s to 1990s+ SSTAs

Now this may or may not be related to the lack of wintry weather experienced by western Europe (the timing certainly fits), but this could be attributed to other factors, not least decadal trends in the oceans.

Now that was a proper analysis. What it serves to demonstrate is the context under which we now seek winter cold and snow. A 1980's winter had a quite different SST pattern and in my view a 1980's-type winter is unlikely to return until the SSTs return to a similar pattern.

Ok, here's the first stage of the SSTA analysis. A comparison of the charts for the second week of October over the past seven years and the CET's for the winters that followed:

2000: Winter CET = 4.22

2001: Winter CET = 5.05

2002: Winter CET = 4.48

2003: Winter CET = 4.90

2004: Winter CET = 5.04

2005: Winter CET = 4.01

2006: Winter CET = ?.??

Not really enough data to draw a truly enlightening comparison as it would be nice to have a chart from, say, October 1995 or an October in the run up to an early 90's or 80's cold winter.

The one conclusion I can draw here is that at this stage in the autumn, the North Pacific contained the most extensive positive anomaly at Central Europe lattitude in both October 2000 and 2005 - the coldest UK winters of this series. Although, it has to be noted that otherwise there are a lot of differences between the two charts, notably, the western coast of South America (El Nino/La Nina) and the Northernmost sectors of the North Atlantic. Curiously, in October 2000, alongside the aforementioned positive anomaly, there was the most substantial negative anomaly of all of the charts at European lattitude in the North Pacific, which was not a feature in October 2005.

IF a warm anomaly in this area at this time of year is a good factor in producing a colder UK winter, then this October has some work to do, as the anomaly is way short of the mark.

I'm now going to move on to look at the charts from the winter months, which will arguably have more direct bearing on winter weather patterns, but I won't have the benefit of being able to draw comparison with this year. As the charts are updated on a weekly basis I shall return to the current period to see how 2006 is progressing.

And there is my first SST analysis of the season.

Edited October 12, 2006 by The Enforcer

[BrickFielder]

Now that was a proper analysis. What it serves to demonstrate is the context under which we now seek winter cold and snow. A 1980's winter had a quite different SST pattern and in my view a 1980's-type winter is unlikely to return until the SSTs return to a similar pattern.

And there is my first SST analysis of the season.

I am not sure that is what GP meant. I think he might have been aluding to the North Atlantic SST Tripole where in recent years we have had a cool warm cool tripole as opposed to a warm cool warm tripole (as now). In which case we have returned to the SST patterns of the 1940's - 1960's. SST'S (Pacific and Atlantic) are really only half the story for the NAO with the other half being sea ice and snow cover, which is why a number of people are looking toward the early build up of cold in certain areas of the artic. Clarification from GP required I think.

[BLAST FROM THE PAST]

I am not sure that is what GP meant. I think he might have been aluding to the North Atlantic SST Tripole where in recent years we have had a cool warm cool tripole as opposed to a warm cool warm tripole (as now).

BF I think you read it right, well that's what I'm picking up from it anyway

BFTP

[Optimus Prime]

Finanally the northern hemisphere ice is returning to near average levels again;

Somewhat quicker than last year.

[The Enforcer]

I am not sure that is what GP meant. I think he might have been aluding to the North Atlantic SST Tripole where in recent years we have had a cool warm cool tripole as opposed to a warm cool warm tripole (as now). In which case we have returned to the SST patterns of the 1940's - 1960's. SST'S (Pacific and Atlantic) are really only half the story for the NAO with the other half being sea ice and snow cover, which is why a number of people are looking toward the early build up of cold in certain areas of the artic. Clarification from GP required I think.

Ok well if I adjust my interpretation to say that the 1980's tripole thingy which was good for snow has been replaced by a tripole thingy that isn't as good for snow and that nationwide snowfall is unlikely to happen unless the 1980's tripole thingy returns.

For those who like analogies, here's a good one:

I see the cold vs mild battles of the 1980s a bit like a clash between the Liverpool and Nottingham Forest teams of that time. Liverpool were the stronger side, but Forest were a useful outfit and would win out from time to time. In the 1990's and 2000's Liverpool remained strong (in the context of a league of 92 teams), but Forest slumped. Forest are now battling bravely to get back to their former position, but it is pretty clear that if the two teams played each other on a regular basis, Liverpool would be the victors on almost every occasion. The odd freak Forest success may occur, but only by the narrowest of margins.

Finanally the northern hemisphere ice is returning to near average levels again;

Somewhat quicker than last year.

Hardly inspiring, though. But if the conditions remain good for ice development, who knows?

Edited October 12, 2006 by The Enforcer

[Glacier Point]

I am not sure that is what GP meant. I think he might have been aluding to the North Atlantic SST Tripole where in recent years we have had a cool warm cool tripole as opposed to a warm cool warm tripole (as now). In which case we have returned to the SST patterns of the 1940's - 1960's. SST'S (Pacific and Atlantic) are really only half the story for the NAO with the other half being sea ice and snow cover, which is why a number of people are looking toward the early build up of cold in certain areas of the artic. Clarification from GP required I think.

not so much of the tripole but dipoles or couplets these days Brick, but yes, very much a return to 1940-1960 dodecadal patterns of pretty warm north Atlantics:

+ve anomalies in the field 55 - 70 N, less +ve or -ve in the field 35 - 45 N will still do the job.

[oldsnowywizard]

hi not sure if this has been mentioned yet... there is a very positive change from the anomolies from this time last year to this year in the artic regions. I distinctly remember very high anomolies being present for most of last winter and a few years before?

... now look at the negative anomolies..

[The Enforcer]

OK here's a look at the SSTA charts for the first week in January followed by the CET for that month:

2001: + 3.2

2002: + 5.5

2003: + 4.5

2004: + 5.2

2005: + 6.0

2006: + 4.3

Edited October 15, 2006 by The Enforcer

[Glacier Point]

It's very hard to make a direct link between one month's CET and SSTAs, especially so during January which is highly influenced by stratospheric and broader hemispheric factors. From 2001 to present, those plots illustrate a range of ENSO conditions and we should also point towards the AO being in very different leading modes for these months.

However, a more trend-based analysis might provide more useful. Here are the reanalysis plots for the period August - November preceding those years and the plot for August - September this year....

and 2006 so far...

Arguably, this year has seen the greatest differential in anomalies between latitudes 55 - 70 N and 35 - 45 N which should translate to an increased probability of the NAO in a -ve state this winter.

GP

[summer blizzard]

Wow i am suprised by how much the current sea surface temperature setup matches that of the weak El Nino compsites.

[summer blizzard]

Looking at the latest sea surface temperature charts, several things now spring out at me, these are:

1) Continuation of warm anomolies over Europe although more average anomolies in the eastern Mediterranian

If the UK is to experience a below average winter, the anomolies in the Mediterannian must become below average or an Azores Low/downstream European Ridge is encouraged

2) Above average ice development around Greenland and warm anomolies allied over cold anomolies in eastern Atlantic favours a strong Greenland ridge and trough to the south west of the UK although as long as anomolies in the Mediterrranian are not below average, a cutoff low is encouraged to develop with energy going into a northern arm of the Jet Stream.

3) The western Atlantic has been warming in relation to average recently favouring a strong ridge in the western Atlantic and probable neurtral to negative PNA, while this is serving to amplify the Jet Stream, this is also serving to encourage the ridge over Europe.

4) The anomolies in the eastern Pacific, favor a positive PNA pattern which should encourage the anomolies in the western Atlantic to reduce in strength and eventually favour a breakdown of the Euro ridge, below average temperatures over the central southern planes are favoured although a shallow Alaskan Trough may develop if El Nino and the QBO carry on strengthening.

5) The anomolies in the Pacific overall favor a neutral PDO value for October with the PDO going positive in November, this serves to encourage the positive PNA pattern.

[summer blizzard]

Looking at the latest sea surface temperature charts, the things that spring out at me are:

1) 1) Continuation of warm anomolies over Europe although more average anomolies in the eastern Mediterranian...

This favours the downstream high over europe.

2) Tripole pattern now in place...

One stumbling block to this would appear to be the massive warm anomoly to the south of Greenland however once Hudson Bay has iced over, the cooler warm anomoly in the central Tropical Atlantic will overide the Newfoundland warm anomoly drawing the Jet Stream south.

3) The western Atlantic has cooled recently encouraging the tripole pattern and promoting a more positive PNA

4) The East Pacific has now developed a tripole pattern, which is typical of El Nino, while the Alution Low may favour a northerly Jet Stream now, due to a warm Hudsons Bay, once Hudson Bay is frozen, this will favour a positive PNA pattern over the USA

5) The anomolies across the whole Pacific continue to favour a neutral PDO value, with a trend towards positive

6) Nino region 3 has had its warm pool eroded and sub-surface waters favour a weakening of the current El Nino, this may mean that El Nino has peaked, or that a peak will occur soon, either way, i expect a weakening El Nino throughout winter

The current sea surface temperature anomoly setup is being overriden by either the AO, El Nino or the QBO.

[summer blizzard]

As you can see, the Baltic Sea is now below average..

I will give a detailed update on the current sea surface temperature anomolies later tonight.

[Iceberg]

The baltic has indeed gone below average, quite amazing considering the large postive anom's that existed there even a month ago.

Go's to show the effect of wind and strong LP systems on the water rather than cold though.

Some intesting changes in the SST charts though.

BTW I wouldn't suggest cross using SST charts i.e the NCEP reconstructions using Reynolds and the Unisys charts as an example, the differences in the base values etc are quite large.

The big changes in SST's though in the last 2 months is why I am highly sceptical of any LRF's for this winter, unless your going to predict major SST trends as well (and get them right) it turns into a guess.

Time to investigate the various SST charts in a bit more detail......

Sorry and baseline baltic temps

Edited November 10, 2006 by Iceberg

[Iceberg]

Forget what I just said

Parts of Finland on the baltic are showing a -4C anom over the last 30 days so it's certainly a mixture of temp and wind.

[osmposm]

Forget what I just said

Parts of Finland on the baltic are showing a -4C anom over the last 30 days so it's certainly a mixture of temp and wind.

And the Baltic responds extremely quickly to temperature change because it is so shallow; it also freezes very readily - particularly at the northern end of the Gulf of Bothnia - because its salinity is very low.

Indeed, if you look ( http://www.fimr.fi/en/itamerikanta/itameri...jaatilanne.html ) at the last ice map (for 30 Oct - they only do it once a week), at that point the water temps were warmer than av. I don't actually think that the current (6 Nov) situation is significantly ahead of normal - it's difficult to tell because the comparison date is 5 days earlier. But it's certainly perfectly normal for freezing to begin up there in early November.

Edited November 10, 2006 by osmposm

[BrickFielder]

SST's in the pacific look like playing a large part in the weather. Typical El Nino conditions where the jet sinks south over the US and low pressure is located in the Gulf of Alaska. The passage of storms has created a further band of warm water further north which is creating high pressure towards the aleutians.

Closer to home and the jet is likely to want to climb north along the eastern seaboard of the US which will create periods where we have a mid atlantic blocking pattern. It looks like being too far west though for the associated trough over western europe to be positioned so that we are in the cold air. Ireland looks in a better position but this pattern will probably retrogress west as el nino matures.

At the same time or in combat with the above scenario warm seas south of greenland are creating high pressure ovr greenland.

Short term we should expect mild wet weather from low pressure systems parked to our west with short northerly spells as atlantic blocks break. Interspersed with this should be atlantic low pressure systems blasting across to the north of the UK.

Longer term the mild wet weather will sweep warm air to our north warming the seas there. This increases the likihood of high pressure developing to our north bring cold continental wind from the east. Retrogressing pattern due to maturing el nino may cause ridging towards the UK.

Of course it never works out as simply as this and these are just indicators.

[Glacier Point]

The persistence of warm SSTAs in the central and western Pacific has been a feature of the last few months.

This is very much a pressure anomaly pattern associated with a -ve Pacific Decadal Oscillation (PDO):

(remember this is a correlation reanalysis, so a -ve PDO is the reverse of the SSTA and pressure anomalies shown) which is very consistent with ECM height anomaly modelling at present:

http://www.meteo.psu.edu/~gadomski/ECMWF_0z/hgtcomp.html

The lag effects of the SSTA are also probably influenced by increased amounts of blocking across Siberia and the Kamchatka Peninsula, often associated with this time of year.

Whilst this pattern may be quite difficult to shift and is key to downstream influences over western Europe, it will probably 'flip' quite dramatically as the maturing El Nino signal described by Brickfielder and colder air spilling off Asia serves to drag the jet soutwards and decrease pressure over the Gulf of Alaska.

GP

[BLAST FROM THE PAST]

SST's in the pacific look like playing a large part in the weather. Typical El Nino conditions where the jet sinks south over the US and low pressure is located in the Gulf of Alaska. The passage of storms has created a further band of warm water further north which is creating high pressure towards the aleutians.

Closer to home and the jet is likely to want to climb north along the eastern seaboard of the US which will create periods where we have a mid atlantic blocking pattern. It looks like being too far west though for the associated trough over western europe to be positioned so that we are in the cold air. Ireland looks in a better position but this pattern will probably retrogress west as el nino matures.

At the same time or in combat with the above scenario warm seas south of greenland are creating high pressure ovr greenland.

Short term we should expect mild wet weather from low pressure systems parked to our west with short northerly spells as atlantic blocks break. Interspersed with this should be atlantic low pressure systems blasting across to the north of the UK.

Longer term the mild wet weather will sweep warm air to our north warming the seas there. This increases the likihood of high pressure developing to our north bring cold continental wind from the east. Retrogressing pattern due to maturing el nino may cause ridging towards the UK.

Of course it never works out as simply as this and these are just indicators.

Excellent summary there BF. And the timespan....I reckon we will see the change begin around mid to late December where we will begin to see LPs take a NW to SE direction as pressure builds to the NE 'wantin' to retrograde so we could well experience the type of weather you describe for about 5 weeks yet.

BFTP

[Iceberg]

Good summery,

Very much in keeping with the NCEP US forecast.

However off the US Eastern seaboard where the two jet meet we are going to get some rapid cyclogensis, it's difficult to see this moderating much, unless the Jet can be forced south.

I've also included the latest ENSO forecast, which shows only a stronger EL NINO occuring.

Does anybody know why the pattern will retrogress ?, is it just due to the continued cooling of the oceans in the NH. ?

[summer blizzard]

Looking at the latest sea surface temperature charts, the things that spring out at me are:

1) There now seems to be an even split over Europe with the west being warm, and the east being cold in terms of the Mediterranaian and Batltic...

This favours the downstream high over western Europe but a trough over Eastern Europe which opens up the possibility of retrogression.

2) Tripole pattern in place and developing...

3) The north of Hudsons Bay looks to be cooling, leading to ice buildup.

4) The mid and low lattiude central Pacific has developed a warm anomoly at low lattitude and cold anomoly at mid lattitude favouring a northerly Jet Stream in the central Pacific...

This will encourage a positive PNA pattern and may also indicate a weakening of the westerly QBO because warm water at low lattitudes indicates easterly trade winds.

5) The anomolies across the whole Pacific continue to favour a neutral PDO value, with a trend towards positive

6) El Nino looks to be fairly static with weekly drops and rises...

I expect anomolies to peak this month and slowly reduce over the next few months.

In summary, while i have no problem with the sea surface temperature anomolies in the Pacific, i do have problems with the western Mediterranian and eastern Atlantic, as long as the western Mediteranain remains warm, a downstream ridge will be favored over western Europe and we will be in danger of a winter 2002/2003 senario with a Positive PNA leading to a southerly tracking Jet Stream coming out of the USA but rising northward over Europe with a lot of topplers.

Also, my punt for December 1st-10th based on these anomolies would be for a toppler followed by the high taking up a Bartlett position before retrogression into the mid-Atlantic again.

Edited November 13, 2006 by summer blizzard

[Stratos Ferric]

SB,

I have to say that I think you greatly overestimate the significance of the Med when it comes to forcing the jet. Also, whilst there is an even split between E and W across a compass dial, even a crude check suggests that in terms of oceanic surface area the split is rather less even.

[summer blizzard]

I must disagree with you Stratos Ferric, the Mediterranian is a large body of water, large enougth to encompase an area of low or high pressure.

I don't know if that was the best way to explain it and i will try and find some evidence.

In regards to the Mediterranian split, it was a generalisation.

[smich]

What amazes my untrained eye about that SST chart is how anomalously warm the NH is, and how anomalously cold the SH is.

Also, the El Nino anomaly looks rather pathetic compared to the western atlantic :blush:

smich

Edited November 13, 2006 by smich