Winter 2012 / 2013 Part 2

[BLAST FROM THE PAST]

Important though that these are anomalies, 07/08 clearly demonstrated that its far from a given. Let's hope there is a good confirmed correlation but it suggests to me we need to compare other variables in play at the time. Personally I think ice minima is a consequence of the 'bigger' workings and not causation.

BFTP

[feb1991blizzard]

That is called climate forecasting, which is completely different from forecasting what will happen in 3 months

Yes but there are so many more variables (both weather and climate related) that are going to happen over the next 100 years that it is still too hard to predict, weather may override climate, we dont know, the only thing we do know is that one day our planet will come to an end, who knows whether it will be because its uninhabitable because its too hot, too cold, too much CO2, too little O2 or because the sun shrinks into a red dwarf, because of a massive scale nuclear holocost and whether it will be in 50 years, 100 years or a million years.

[bobbydog]

OK, here is the pressure anomaly pattern for the middle part of the atmosphere during the top ten most positive Arcitic Oscillation winters and alongside it the sea ice maxima (untrended) during September:

and reversed, the top ten negative AO winters and sea ice minima during September:

Note that the deepest anomalies are focussed around Greenland and NW Europe for both sea ice and AO. In other words, the predictive skill shown in forecasting the state of the AO would appear to be the key for European Winter forecasts amd this appears to have some correlation to the extent of sea ice cover in autumn.

What's interesting here is that we have a variable (anomalous sea ice extent) which appears to precede the AO winter state by some months and a proposed series of mechanisms by which it influences the subsequent state of the AO.

as it slowly comes together it becomes ever more complicated! for example, we discussed the link between annual or, year round, (rather than just winter) ozone levels, having an influence on the arctic strat, (higher levels leading to warming) which could influence ice extent. which have been falling on roughly the same timescale. in recent years, ozone levels have been rising. which should mean that arctic ice should begin to recover. however as it stands now, a warmer strat and the potential increase in snowfall due to less sea ice, should point to a higher chance of a colder winter. one thing i have noticed is that some signals also have the potential to cancel each other out!

[BornFromTheVoid]

Important though that these are anomalies, 07/08 clearly demonstrated that its far from a given. Let's hope there is a good confirmed correlation but it suggests to me we need to compare other variables in play at the time. Personally I think ice minima is a consequence of the 'bigger' workings and not causation.

BFTP

Hi BFTP. Would you mind elaborating on that?

as it slowly comes together it becomes ever more complicated! for example, we discussed the link between annual or, year round, (rather than just winter) ozone levels, having an influence on the arctic strat, (higher levels leading to warming) which could influence ice extent. which have been falling on roughly the same timescale. in recent years, ozone levels have been rising. which should mean that arctic ice should begin to recover. however as it stands now, a warmer strat and the potential increase in snowfall due to less sea ice, should point to a higher chance of a colder winter. one thing i have noticed is that some signals also have the potential to cancel each other out!

You have the ozone thing a little off! The idea was that the loss of ozone may have led to a cooler stratosphere, enhancing the vortex and thus causing a more +ve AO, which helped by shipping extra ice out of the Arctic. The +ve AO trend reversed around 2000, but the sea ice decline actually accelerated, so even with a recovery in ozone, it doesn't seem likely that the sea ice will recover.

[bobbydog]

Hi BFTP. Would you mind elaborating on that?

You have the ozone thing a little off! The idea was that the loss of ozone may have led to a cooler stratosphere, enhancing the vortex and thus causing a more +ve AO, which helped by shipping extra ice out of the Arctic. The +ve AO trend reversed around 2000, but the sea ice decline actually accelerated, so even with a recovery in ozone, it doesn't seem likely that the sea ice will recover.

yes you're right (of course!) i think i must have fried my brain with too much info!! (or beer lol)

edit- just re-read our conversation about ozone and realised i contradicted myself with the above post. i concluded that trying to be clever and carlsberg don't mix!

Edited October 2, 2012 by bobbydog

[feb1991blizzard]

-5c uppers projected, i may be wrong but this could be the first time this Autumn that anywhere in the UK has appeared under -5 850s on an operational run of a short - medium range model.

[UV-RAY]

Hi BFTP. Would you mind elaborating on that?

You have the ozone thing a little off! The idea was that the loss of ozone may have led to a cooler stratosphere, enhancing the vortex and thus causing a more +ve AO, which helped by shipping extra ice out of the Arctic. The +ve AO trend reversed around 2000, but the sea ice decline actually accelerated, so even with a recovery in ozone, it doesn't seem likely that the sea ice will recover.

BFTV, I'm not so sure if there is any correlation between cold winters and reduced summer ice, if one looks at the winter of 2007/08 following the huge melt of that that season then you could argue there is absolutely no correlation. There are as BFTP states other variables at work with solar output and a -PDO the most likely factor in my opinion.

[Radiating Dendrite]

BFTV, I'm not so sure if there is any correlation between cold winters and reduced summer ice, if one looks at the winter of 2007/08 following the huge melt of that that season then you could argue there is absolutely no correlation. There are as BFTP states other variables at work with solar output and a -PDO the most likely factor in my opinion.

It is often percentage chance though.

A lack of ice may increase the chance of a cold winter. This does not mean that a cold winter will always happen though.

[UV-RAY]

It is often percentage chance though.

A lack of ice may increase the chance of a cold winter. This does not mean that a cold winter will always happen though.

I'm far from convinced it does though, I think it's more a case of looking for something that's not really there. Since 2007 we've had two winters that produced very cold periods, this for me ties in with -PDO and low solar output both of which increase our chances of colder winters. Edited October 3, 2012 by Seven of Nine

[BLAST FROM THE PAST]

Re lack of ice and jetstream disruption/slow down. What I'm alluding to is that the jetstream behaviour started before the record low ice autumn 07 and I believe that the low ice is part of the mechanism that has disrupted the jetstream and not the reason for it eg PDO, perturbation cycle [ENSO]. solar cycle possibly entering grand minima etc.

It does seem apparent that one driver/teleconnection alone does not bring a cold winter but a combination is required.

BFTP

Edited October 3, 2012 by BLAST FROM THE PAST

[johnholmes]

Looking for links to predict what you want to see is one of the major problems. Unless rigorous statistical checks are made on the two series of cases that are found then there is a lot of doubt over any findings. Not only does the researcher have to find occasions that match the desired result, a similar series of tests has to be run for the negative results. Only then can a true picture be seen.

It does seem apparent that one driver/teleconnection alone does not bring a cold winter but a combination is required.

Without doubt it is not one but several IF there is in fact a link. I think it is great that folk are trying to find a link or links but it does bear thinking about. No professional centre has yet even pretended to know how to use the undoubted effects some things have on subsequent seasons.None of them have yet found the links. Googling shows just how much professional research into this is going on.

Edited October 3, 2012 by johnholmes

[Methuselah]

As we all know (or assume or whatever) from all the arguments relating to atmospheric CO₂ and global temperature changes, a temporal correlation between two separate phenomena, however much we may desire it, doesn't prove any causal link exists between them...

Just how a Grand Minimum (should it even materialize?) can be the cause of the recent demise of the Arctic sea-ice is unclear to me: where are the mechanisms? It seems, to me at least that, for such a case to ever be 'proven', a great deal more research will need to be done - and a lot more analysis carried-out?

[garbagebags]

Correct me if I am wrong but doesn't low sea ice mean, warmer Arctic air rising, therefore warmer Strat, therefore more chance of -NAO -AO and harsh UK winters?

[Methuselah]

Correct me if I am wrong but doesn't low sea ice mean, warmer Arctic air rising, therefore warmer Strat, therefore more chance of -NAO -AO and harsh UK winters?

Now those mechanisms I can see...

[BornFromTheVoid]

BFTV, I'm not so sure if there is any correlation between cold winters and reduced summer ice, if one looks at the winter of 2007/08 following the huge melt of that that season then you could argue there is absolutely no correlation. There are as BFTP states other variables at work with solar output and a -PDO the most likely factor in my opinion.

In the same way you can just as easily use 07/08 or 11/12 as proof against the -ve PDO and low solar. A correlation doesn't mean they follow each other exactly. With the sea ice, it just means an increased liklihood of a cold winter when the sea ice is low.

I'm far from convinced it does though, I think it's more a case of looking for something that's not really there. Since 2007 we've had two winters that produced very cold periods, this for me ties in with -PDO and low solar output both of which increase our chances of colder winters.

If I only used years since 2007, then you would be right. But I didn't, and none of the peer reviewed studeis I linked to did either! Even in the composite maps, most years used were before our recent cold winters set in.

Besides there are clear physical mechanisms for the link, which would need to be disproven before beginning to claim there is no correlation.

Re lack of ice and jetstream disruption/slow down. What I'm alluding to is that the jetstream behaviour started before the record low ice autumn 07 and I believe that the low ice is part of the mechanism that has disrupted the jetstream and not the reason for it eg PDO, perturbation cycle [ENSO]. solar cycle possibly entering grand minima etc.

It does seem apparent that one driver/teleconnection alone does not bring a cold winter but a combination is required.

BFTP

I think the sea ice is one of the main contributing factors towards the slow down in the jet stream. When the thermal/thickness gradient has been changed so much, there has to be some impact. The fact that the change in the jet stream is strongest in Autumn when the heat is being released from the Arctic ocean lends a lot of weight to the sea ice reduction influence.

I don't think anyone is claiming any one things causes a cold winter, but it is nice to see so many encouraging signs!

Edited October 3, 2012 by BornFromTheVoid

[UV-RAY]

In the same way you can just as easily use 07/08 or 11/12 as proof against the -ve PDO and low solar. A correlation doesn't mean they follow each other exactly. With the sea ice, it just means an increased liklihood of a cold winter when the sea ice is low.

If I only used years since 2007, then you would be right. But I didn't, and none of the peer reviewed studeis I linked to did either! Even in the composite maps, most years used were before our recent cold winters set in.

Besides there are clear physical mechanism for the link, which would need to be disproven before no beginning to claim there is no correlation.

I think the sea ice is one of the main contributing factors towards the slow down in the jet stream. When the thermal/thickness gradient has been changed so much, there has to be some impact. The fact that the change in the jet stream is strongest in Autumn when the heat is being released from the Arctic ocean lends a lot of weight to the sea ice reduction influence.

I don't think anyone is claiming any one things causes a cold winter, but it is nice to see so many encouraging signs!

I wasn't having a go at you BFTV and you raise some interesting points, as usual. I think most of us are scratching around trying to find correlations between all of these events and colder winters. A bit like finding a needle in a haystack really.

[gottolovethisweather]

This is starting to feel like the technical discussion thread in here.

Intriguingly, last night, one or two of the posters in the MOD thread were seeing things the way I have been for a while, with the likelihood of a much cooler October possibly coming our way. For that to happen, we need some solid trending within the outputs and any such development will not happen until the second daughter and Nadine herself are removed from the scene, later next week. I know wish for the predicted build-up of snowfall over the required regions to materialise.

In spite of my first point, as ever I have liked (literally) all the input you guys have put in, please keep it up.

Edited October 3, 2012 by gottolovethisweather

[BornFromTheVoid]

I wasn't having a go at you BFTV and you raise some interesting points, as usual. I think most of us are scratching around trying to find correlations between all of these events and colder winters. A bit like finding a needle in a haystack really.

Ah I know. There just seems to be some kind of inertia with regards to people taking changes in the Arctic seriously as a contributor to the weather in mid-latitudes.

I suspect it stems from the fact the the sea ice loss is often held up as proof of anthropogenic global warming. Put putting that debate to a side, whatever people believe the causes are doesn't really matter here. The Arctic is changing very quickly and the feedbacks from that are changing the meridional temperature and thickness gradients, which are fundamental drivers of the globes atmospheric circulation systems.

In the end, at least from looking at different teleconnection and trying things out, we'll at least learn a few things along the way, even if we don't improve our own LFR abilities!

[Polar Maritime]

Glencoe range has had a dusting last night.

[Gavin Hannah]

Glencoe range has had a dusting last night.

As did Cairngorm. Posted photos in the Snow & Ice thread.

[laserguy]

Put putting that debate to a side, whatever people believe the causes are doesn't really matter here. The Arctic is changing very quickly and the feedbacks from that are changing the meridional temperature and thickness gradients, which are fundamental drivers of the globes atmospheric circulation systems.

Ye,squabbling aside ( done enough of that!), am I alone in feeling a little privileged to be around to witness what transpires, be it tropical winters/ ice age UK or ( ugh ) no change at all?

[Gavin Hannah]

Ice age winters and tropical summers would do nicely every year. With "just nice" conditions in between, but we all know that's not going to ever happen. Well, the tropical summer bit probably least likely to happen.

[BornFromTheVoid]

Ye,squabbling aside ( done enough of that!), am I alone in feeling a little privileged to be around to witness what transpires, be it tropical winters/ ice age UK or ( ugh ) no change at all?

Agreed, somewhat. Even before I knew anything about climate change or the implications of it, I always had a fascination with things from extreme weather to super volcanoes and earthquakes, which is why I got into studying earth science in the first place!

There is something of a morbid fascination with these things, even knowing the destruction and often the loss of life associated with them. The same is true I'd say with many people here and extreme winter weather, be it cold/snow or storms.

[Glacier Point]

2007/8 is worth looking at w/r/t the sea ice debate because it highlights I think that it is not the 'killer' relationship and can be overidden by other factors.

In this case, look at how the global circulation was strongly Nina like during the summer and autumn (the largest -ve angular momentum anomaly for this period) and continued to develop into a full blown La Nina during that winter. Nothing will kill off winter cold prospects like a La Nina prevelant from the late summer onwards because its impacts on the meridional circulation and consequent Brewer Dobson interference.

[Methuselah]

2007/8 is worth looking at w/r/t the sea ice debate because it highlights I think that it is not the 'killer' relationship and can be overidden by other factors.

In this case, look at how the global circulation was strongly Nina like during the summer and autumn (the largest -ve angular momentum anomaly for this period) and continued to develop into a full blown La Nina during that winter. Nothing will kill off winter cold prospects like a La Nina prevelant from the late summer onwards because its impacts on the meridional circulation and consequent Brewer Dobson interference.

Agreed GP; it's no more than another piece in an already highly complex puzzle...But it's always going to be in the background, from now on... Especially when considering the fact that the (expected by some) Solar Cycle-induced sea-ice recovery now looks to be even further from happening?