(I was meaning to post in this thread, certainly got the two mixed up tonight 2012 snow and this one)

The AO and AAO (SAM) values are very interesting and informative numbers. This week I have learnt a lot more about them than I previously understood because I was able to look at over 60 years of monthly data for both NH and SH. Thanks to roves for posting the link to the SH data back the 1948 that was able to shed a lot of light on my understanding. The data for NH from 1950 is already on the NOA website.

The daily values themselves on a daily basis are only like the weather and difficult to interpret, its not until you start to average out the readings that you start to see what is happening. Previously I had only ever looked at the monthly average figures back to 1979 shown here.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/month_aao_index.shtml
I could immediately how well snowy winters correlated with low values and bad winters with high values. However even at the monthly scale you can see that its only extended low values that correlate with the really good seasons like 80-81 leading to the massive 81 season and 90-91-92 leading to 3 really big snow years. Bad years you can see correlate well with high values like 82, 93.

However even at the monthly scale you still cannot see all that is happening, it was not until I plotted the values at a 10 year running mean that my eyes popped out. Suddenly you can see that the SAM has been rising quite consistently for 60 years with the last 11 years near a plateau. This is a clear sign of a contracting polar vortex. However when looking at NH AO equivalent although there is also a rise it is far from linear.

To understand this you need to realize what the SAM is. It is a temperature differential between the sub tropics and the polar region like a gradient or waterfall that can be steeper or flatter. However because the Earth is constantly going through complex temperature exchanges between the tropics and the poles the gradient is also fluctuating, from a high gradient (high SAM) to low gradient (low SAM). When there is a steep gradient for cold fronts its like they run into brick walls trying to get North and slide away, but when there is a low gradient they can much more easily depart the polar regions and slide North. Because it takes cold fronts weeks to get organized to have a chance to move North a brief drop in SAM allows only a small window of opportunity, its need to be extendedly low to have the best effect.

Because the SAM is a gradient its likely that there are limits to how high or low the value can go. What a positive value really means is a net heat gain in the lower latitudes relative to high latitudes which squashes the polar vortex. Now the interesting thing is that what the SAM shows is that Antarctica has barely been warming at all while the low latitudes have been warming much faster which is why the value is positive and the polar vortex is squashed further South than what is has been decades ago. However in the NH the AO has been able to reset itself back to zero a number of times and is more dynamic. Notice how the AO reached a peak in 1998 at the height of the large El Nino, this suggests that the El Nino was the largest heat input into the low latitudes of the NH to cause such a high value. However after the El Nino ended the SAM reset itself in the NH and this led to some of the severe winters of the 2000's in the NH.

The NH AO is able to reset itself much more easily because of the excess land masses. The heat is able to migrate to the North pole and rebalance the AO. This is exactly what we saw, large polar warming because the heat can migrate to the pole that caused the AO to drop suddenly and cause those cold winters but also low Arctic ice levels in the latter 2000's. But the AO is also struggling to get much below zero because of the excess warming in the low latitudes of the NH. The recent AO rise last winter was another rebound but without an El Nino it is not that strong yet. Once we get another El Nino more heat will be sent to the North Pole and the cycle may begin again.

It seems the SH may also be reaching a limit because the SAM is plateau-ing now. However because of the configuration of land masses in the SH it is unclear if there can be any reversal like in the NH. Because it is so difficult to get any heat down to Antarctica it may well stay colder down there relative to the low latitudes and keep the long term SAM mean high. That is why the tend looks like a one way trend for 60 years.

It is interesting that in a way something snapped even in the SH in 2000 after the El Nino but it was only brief and failed to register on the 10 years trend. Rather for us the left over's have been nearly no effect on Antarctica but a permanently elevated SAM because of the heat left over in the low latitudes from the El Nino. By rights a strong La Nina should have been enough to turn around the SAM trend, but because Antarctica is so isolated from heat and heat is still excess in low latitudes, so far we are still not making much headway.

Unless some mechanism that has not happened yet can rebalance balance the heat differential between Antarctica and lower latitudes like Australia we cannot get decent cold fronts. We need to see SAM at least reset itself like the NH AO, but just not sure if the SH oceans will ever allow it.

SAM + 10 year moving mean since 1948


NH AO + 10 year moving mean since 1950

The solar slowdown with lag will fix the SAM as solar flares slowdown and less ozone is destroyed and jetstreams move north once again and SAM returns to more normal values after the strong 1000 nyear solar peak of the nineties with high SAM values.

Fantasic research there Peter! Thanks for that

Glad a few people liked my post, it was an eye opener for me too. Its all thanks to our combined knowledge base on this forum that new ideas and new information can be analyzed.

BD, the historical information in you linked PDF also helped me out. I just wanted to comment on the ozone you mentioned, I disagree that it has any effect on SAM or AO. These values are based on global heat distribution on which a little more or less UV will make about as much difference as a cup of tea dropped in Sydney harbor. Completely insignificant, because the little difference in UV makes almost no difference to heat uptake of the atmosphere.

Solar cycles could do something, I am still sitting on the fence with that. I do believe that past climate cycles could have been primarily driven by solar cycles. However of all the factors affecting the changes of the last 50 years, I think that our role may actually have been the largest contributor. We have been able to measure all factors quite accurately over recent decades and non really stand out except one. Despite past Earth history not showing that IR absorbing gasses were a driver to change, it is still possible that we are causing a forcing to change that has never happened before in Earth history.

Solar flares detroy ozone ther is ample evidence to show that, so if solar is up more ozone will be destroyed and if solar is down vice versa.
Ozone hole has been shown to move jetsreams and westerlies south with low levels of ozone and larger hole and vice versa, That is the link, Peter.

BD I have been unable to find any proof or explanation of what is happening in the Stratosphere affecting the Troposphere. It all seems to be based on correlations that are not proven.

However that said I still agree there could be some effect there that originates from solar activity and ends up affecting weather at the surface. But I think still more likely to be caused by changes in solar output associated with solar activity that we do not have accurate records for prior last century.

In this link they just do not know at all....
http://presenters.climaterealityproject.org/news/article/402
"The culprit for this shift appears to be ozone depletion, though the exact mechanism of the effect is still unknown."

In this one they can only provide evidence of Troposphere affecting Stratosphere but not vise versa.....
http://www.heatisonline.org/contentserver/objecthandlers/index.cfm?ID=7722&Method=Full
"He and colleagues showed in 2009 that upward movements of air in the troposphere can change the patterns of stratospheric winds."

"These changes, in turn, can be reflected back down to the troposphere and influence weather at the surface of the Earth."

Thus far, this June is perhaps the most benign for frontal weather that I have ever seen in the Blue Mountains. Sure, windy at times but the guts of fronts are rarely reaching us these days. In nearly forty years of watching frontal weather up this way, I've never seen it so benign in June. Strong fronts just haven't been moving north at all, or even over the ski fields for that matter.

There is some indication now of stronger fronts developing but upper support looks quite weak on the charts, at this stage. July might bring stronger frontal weather, lets hope, for the sake of the ski fields. Its looking pretty poor down there.

I have a lot more references Peter but I have just so much work forecasting here. I have had tio go back and do all my weather and climate models from scratch as my computer files from years of upgrading had become unwieldy, extremely huge, slowling the computer processes, and hard to follow as to what was causing which result...but the hard work ios yielding excellent results and showing extra information, so well worth it. but still a lot of work to polish off, so I am very limited with time atm!
But U are right the solar is composed of many outputs most of which have not been recorded till recently, which makes it more difficult to research.
But, I have very good research results myself, most of which I cannot reveal atm unfortunately as I run a forecasting business.
cheers

Temperature anomalies in the Antarctic have been increasingly rising since Feb 2012 and now in May 2012
the Antarctic has the warmest anomalies on the globe for MAY
What this means for our southern latitude fronts l have no idea?



PDuke in the snow thread said 2008, 2007 and 2011 were good snow years and yet the Antartic anomalies for 2008, 2007 and 2011 were also exceptionally warm which you would not expect?
How can warm Antarctic warm anomalies drive cold fronts and produce good snow years?
Weather is so elusive and unexpected!!

JULY 2008 anomalies from the archives
ftp://ftp.bom.gov.au/anon/home/ncc/www/cmb/850t/anomaly/month/colour/history/global/



2007 JULY ANOMALIES : a good snow year



2011 JULY anomalies : a good snow year


Might check the correlation with poor snow years tomorrow

Why are the Antartic anomalies so high ??

Yes, that is right, warmer temps in the polar region cause the polar vortex to expand because the gradient is reduced and SAM is lower. 2008 was unusual that SAM still remained high despite anomalies that would suggest otherwise. But seems the anomalies were the more important factor that pushed cold fronts further from the polar region.

I too was quite surprised when I found out how this works a few years ago. It would be interesting to know if solar activity can raise/lower polar temps slightly causing this effect.

crikey - 2007 and 2011 were not good snow years at all for Victorian resorts, especially those that rely on cold south-westerly flows (i.e. Mt Buller).

Are you sure about that?

2007,2008 and 2011 were not what I would classify as good snow years. In fact the maximum snow depth failed to reach the long term average in each of those years.

I think Peter's previous post on how the SAM influences the penetration of cold fronts into VIC and NSW was quite interesting and makes a lot of sense to me. I accept the assertion that this signifies that unless we see a return to more negative SAM events we will continue to see a higher prevalence of low snow depth years.

I wonder how this ties in with SOI and PDO values. These both to some extent give an indication of how heat is built up in the tropics and redistributed towards the poles. I would imagine that higher SOI and lower PDO values in the longer term ( say 5-10 years running trends) would be expected to lead to lower SAM values in the longer term.

Incidentally I just updated my SOI chart and put in a 5 yr running mean and the result is startling to ay the least. I will link the chart later today but suffice to that after running at unprecented negative levels for most of the 80's and 90's the pendulum has well and truly swung the other way with the 5 yr running mean now at 7.3. For some perspective the previous 2 highs last century were 5.8 in 1911 and 7.0 in 1976.

To also give some perspective on how deeply negative the SOI was during the 80's and 90's, the 20 YR running mean is yet to go positive (and the 30 YR is still running at -1.5. The movement of this index really needs to be understood if we are ever to get a more accurate read on what factors are influencing global climate.

That is how NH works also colder England Europe latitudes is normally warmer North Pole area as jetstreams move further southwwards in low solar years.
And AO is lower in unison.

Glad to see you getting excited about that correlation LOCKE
Let me guess your results before you post
Overlay your SOI results on scafettas 3 frequency model posted below
Around 2000 the SOI started trending positive again.. is that right?
and according to his generic axis the SOI would not return to 1911 values until 2033 ( if l have interpreted this axis correctly)
Could you confirm that? Extrapolation
2000 to 2033 trending to cumulative positive SOI phase,
NINA/cool
( hope l got my positives and negatives around the right way)
trending to increased occurrence of NINA SOI values and cooler temps?
min and max phases that scafetta pinpoints as seen by the blue and red lines l have marked on this map . Scafetta has marked a number of smaller sub cycles within the larger cycle ,that oscillates between NINA and NINO


In fact l have seen even smaller sub cycles within those smaller cycles of much smaller time periods in both Surly bond and apocalypse research on rainfall

I am not sure if l have done credit to scafetta's( 2012) work but l have seen the correlation in his model with shifts in the SOI identified by members in this forum

whoops of thread topic

Could someone please tell me what are the official good snow years and what are the official poor snow years ?.
It would be useful in doing some correlation with some weather dynamic variables

How is a good and poor snow season officially measured??
spencer creek or Buller etc?

Thanks for the info and input 'guys' very helpful and interesting

I read a WZ weather article tonight talking about the role of jetstreams in the series of cold fronts to come this week. The last week of JUNE 2012
http://www.weatherzone.com.au/news/wet-and-gloomy-days-ahead-for-melbourne/21917
Thought it might be good to have a look at what is going on in the upper 200hpascal where the jetstreams typically reside
Here is the forecast 200 hpascal upper jet streams forecast for this Thursday by ACCESS interactive


http://www.bom.gov.au/australia/charts/v...it=Refresh+View




Throughout this event, the 200hpascal subtropical jetstream is looking very strong over the course of this cold front and potential snow event
Just powering across mainland Australia
The sub polar meets with the sub polar jet at various points during the next week
On this map the sub polar doesn't penetrate up into the oz mainland and mainly effects Tasmania

I had no idea the sub tropical jet was related to strong cold fronts and snow fall?

As the sub tropical jetstream is not sourced from the polar latitudes nor hangs out there
Anyway .The sub tropical jet is looking strong and persistent across the oz continent
That map is only a forecast so will look forward to seeing how that looks on the day..., being this Thursday.

Big dump of snow on the way
Press Release, Wednesday June 20, 2012 - 14:04 EST

The Australian ski fields are about to be covered with the biggest dump of fresh snow this season and it's starting tonight, according to weatherzone.com.au.

"Widespread snowfalls of 25-to-50 centimetres are likely between tonight and early next week, most of it falling during tonight and Thursday," Weatherzone meteorologist Brett Dutschke said.

"A strong cold front is carrying a cloud band with a reasonable amount of moisture, the same system which brought widespread rain to southwest WA earlier this week. The rain in this cloud band won't take long to fall as snow at most resorts, due to the lack of warm air ahead of it. This front will be followed by another soon after, maintaining snow-bearing westerly winds for several days," Dutschke said.

This is great news for those heading to the snow this weekend or next week.

It has already been a better-than-average start to the season and the snow depth is about 20 centimetres more than at the same time last year. This coming snow will improve the cover markedly. By the weekend the depth should be well above half a metre....."
http://www.weatherzone.com.au/news/big-dump-of-snow-on-the-way/21928

Put together some weather variables for this upcoming strong cold front.. Last week JUNE 2012
below
Note the strong dip in SAM from the 1st to 14th June ( dropped 4 points..WOW) and Now is followed by an equally high increase to the positive by the 20th June ;
that is an increase of 4 points in an even smaller time frame .. One week.. WOW WOW
Will be interesting to see how the cold fronts in the coming week respond
I suspect they will continue to be strong. From my very brief observation of SAM and cold fronts over time .
It is a LARGE shift either to positive or negative that makes a big input to strength of fronts
For some reason small shifts in SAM not conducive to big cold fronts and massive snow dumps..??

Marked the long wave trough on sat' pic'as observed by cloud band which stretches up as far equatorial as nth qld.. wow ( LONG)
Does the LWT come from the cloud area formed by the MJO in phase one?
http://www.bom.gov.au/climate/mjo/

The cold front on the synoptic looks fabulous but surprised the MSLP is not forecast to drop below 1004 and mainly 1008 1012 hpascals Considering the predicted rain and snow?
Thought that was somewhat high. What is the major forcing factor for the rain and snow is it the mid levels?

Good work there Crikey...but, one small thing, imo I don't think the MJO phase has much at all to do with it, really, especially at this time of the year.
Actually, also, it may surprise some that the MSL pressure in the wetter southern winter months mean is quite a bit higher than the summer months mean.
BOM used to show it on site, but I can't find records of it anymore.

Its interesting that even a brief drop in SAM can be enough to attract a cold front. Still I would not call this a strong cold front. Its a fairly standard cold front that would be just one of others that would be stronger. Watching this one pan out, I just cannot help myself comparing to cold fronts just like this that I tracked from WA in 1992 for example. Back then I was forecasting snow based on cold fronts tracking just like this one from WA and always knew I was in for a proper snowfall here with below zero temps and blowing snow. Its interesting how such a small amount of contraction of the polar vortex over last decades has been enough to really notice on the CT's.