BrickFielder

A little bit of a generalisation and partially true. In our latitude the response is generally baroclinic or shallow because wind moves the air away before any deep heating from the warm water can take place (this may not be true mid winter). This according to Lindzen and Nigam would give troughing over a warm anomaly. Yet this is not quite what happens and the response in the north Atlantic seems to be high pressure to the north west and low pressure to the south east of a warm anomaly and this is much more in line with the updated research by Frankignoul. What we should expect according to literatures is for winds to tend to blow easterly across warm anomalies. In this respect we should expect ridging to the north of a warm anomaly. ATMOSPHERIC GCM RESPONSE TO EXTRATROPICAL SST ANOMALIES: SYNTHESIS AND EVALUATION (Peng et al) The patterns of wintertime (December-March), anomalous SST, ocean-to-atmosphere turbulent heat flux (latent plus sensible), and surface wind vectors, associated (via linear regression) with the leading principal component of SST variability in the North Atlantic (a and c) and North Pacific (b and d). Panels a and b are for observations from 1949 to 1999 (data for from NCEPNCAR CDAS-1, Reanalysis). Panels c and d are for the mean of a 10-member ensemble GCM integrations forced with global, time-varying SST anomalies from 1950 to 1999 ECHAM 3.5 GCM data provided by Lisa Goddard, IRI). Heat fluxes are in Wm-2 with positive/negative values in solid/dashed contours every 3 and a thick zero contour. Arrows depict the wind vectors in ms-1 with scales shown in lower left (panel a, c) and upper right (Panel b, d). The SST anomaly values, in °C, are denoted in colors according to scale (note that scale is kept at the –0.5 to 0.5 °C range for overall clarity, however, values in eastern equatorial Pacific extend up to 1.2 °C). Warm anomalies also tend to move north west with time so looking at current SST anomalies we should expect to see High pressure over greenland and low pressure in the central Atlantic which with time should equate to Icelandic or Scandinavian high by winter time. In between and we might expect an increasingly stormy time. This is all theory and the response to SST anomalies is notorious for changing during mid winter and I can not help feeling high pressure and easterly winds are likely to be too far north.

Excellent post by Steve as usual. It is most unusual to have two strongly negative NAO months during the autumn, although it should be noted that with the exception of 1968 it is rare for the NAO not to switch from negative to positive within a month or two. I guess the point to note is that it is strongly negative and is likely to be again over the winter months at some point. 1968 was notable for a particular anomaly in salinity which rather sets it apart from other years and there is not much evidence at the moment for something similar this year. I am not a great fan of analogues either, although I would have said 1998 (cold in the north ,not in the south) was a possible match taking into account the NAO index since January. Definitions of the Atlantic half of the AO and the NAO are subtly different and to some extent this may be reflected in the indexes. What we have noticed over the last month or two is the greenland High being around quite a lot and for high pressure to stick over the continent. This has lead to some pretty warm temperatures up into scandinavia at times and similarly to the north of Canada , leaving ice and cold to build to our north. Ice build up to the east of greenland in the greenland sea at this point in the season has been linked to high pressure over that area during the winter. A number of positive indicators for a cold spell during the winter. Go read Steve's Post in the Learners area about Winter synoptics An Ode To Winter

There is two seperate things being talked about here. Firstly an excellent report on the Temperature Trends in the Lower Atmosphere a report by the Climate Change Science Program and the Subcommittee on Global Change Research, Washington, DC. It really does go into some detail about statistics , measurements and different forcings. It is also interesting to note how the lower stratospheric cooling reflects tropospheric warming. If you really want to know about the current state of Environment Changes Science then I thoroughly recommend you read the report. Temperature Trends in the Lower Atmosphere Secondly is the G8+5 Gleneagles Dialogue on Climate Change being held in Monterey Mexico. This is more of a political arena and seems to be focused on the economics of Climate change. Some of the quotes coming out are a real disappointment from a scientists point of view and have a flavour of making money from climate change. Go read the report it is excellent.

Results are from HadCm3. HADGEM1 reduces the affects of CO2 as a percentage , but it will not be untill HADGEM2 that the carbon nitrogen cycle and atmospheric chemistry will be included. Hadley Center Climate modelling UKCA The carbon nitrogen cycle is about how Carbon is absorbed and this suggest there is a limitation in the understanding of feedback mechanisms to do with CO2 in the climate models. Basically the models do not accurately take into account faster plant and sea CO2 absorbtion due to warming. This sort of implies that a balancing point will eventually be reached. The atmospheric chemistry is a complex business and things like HCFC the alternatives used to CFC's are having large unforecast affects.

The article suggests anywhere between 26 - 80 % of warming is due to CO2 and even this is an estimate. Taking into account the newunderstanding on the links between the stratosphere and troposphere I think I can reasonably argue that CO2 is not the main cause of warming. The last line I think sums it up though.

I am not arguing about whether AGWis happening I am questioning whether CO2 is the main cause. The graph is produced by a combination of measuring air trapped within frozen ice and fossil measurements and I suspect shows semblance of truth. I can see your argument that only the last 650,000 years is relevant . It was interesting to read Dr Corinne Le Quéré report from the british antartic survey group about CO2 level measurements and how CO2 levels noticeably began to rise around 250 years ago. This would tend to coincide with the start of large scale clearing of forests across northern and southern America and across large parts of Europe (Linking reduction in absorption rather than emissions to temperature). If you graph CO2 levels (raw data from the ice cores) and temperatures over the last 300 years then there is at first glance (adjustment for solar output puts it slightly better) poor correlation between temperatures and CO2. The only stastitically conclusive affect on temperatures is by aerosols from volcanic eruptions, which is why I maintain that CFC's and other forms of emission are equally if not more important than CO2. CFC's and ozone

Cloud streams tend to form from two distinct sources. The first is topographical (hills ,sea etc) and the second is due to wind convergence. We may have seen a few unusual streams due to an increase in winds from the east over the last few years, and blocked high pressure patterns which have been on the increase would tend towards more convergence zones developing. It is not beyond the realms of possibility that we have had more streamers over the last few years , although I think I would tend to agree that it is just that we are noting them more often due to radar improvements.

I will be interested to see where you are going with this. It is my contention that quite often statistics, choice of graphical axis to emphasize a point and extrapolation of data are misused. As you say it is quite clear that temperatures have been rising countrywide from that graph ,although the axis is chosen to emphasize the change. As well as looking at temperatures over 200 years perhaps to be fair you should produce one over the last 2 years. Even here graphs may not be reflecting true conditions and perhaps we should seperate day time and night time temperatures. I suspect day time temperatures have not varied as much as night time temperatures and your graph actually indicates an increase in night time cloud cover.

There is a real risk that people get tunnel vision about greenhouse gases and specifically CO2. There have been times on earth when CO2 was significantly higher than it is today and in fact it is only over the last few centuries that large forest fires and grassland fires have been to some extent tamed(Anyone remember stubble burning where fields across the UK were set on fire). Even the science of the greenhouse gas does not work to well, as the dynamics of the atmosphere are different to the air inside a greenhouse. If temperatures increase then more cloud should be produced which reflects more light (depending on the height of the cloud) which reduces temperature. It is a bit like painting the outside of your greenhouse glass silver which just leaves you with a cold dark room. This does not mean the green house affect of CO2 is not real, it means that to some extent it is mitigated and there are negative feedback mechanisms which may limit its affect. By focusing solely on CO2 we ignore particulates, NOX (nitrogen oxides),CFC's and other potentially sources of global warming. No wonder european emission controls are looked apon as being a bit half hearted and focused in the wrong areas. Changes to ozone concentrations and other chemical changes in the stratosphere may well be having a much greater affect on global temperatures than greenhouse gases.

A good article and reasonably well balanced. The question is not one of shutdown but what are the changes which are taking place and what are the root causes of this. Firstly it has been identified that some of the deep water formation sinks are no longer where they were ( Peter Wadhams Research). It has been suggested that there is a natural multidecadal swing between the north and south atlantic of the number of deep water formation areas, although researchers largely attribute this chnage due to global warming. Secondly it has been identified that water moving north around scotland is noticeably less saline which would inhibit the formation of deep water. Thirdly there is no obvious reduction in the gulf stream or volumes of returning deep water ,however there is evidence that mid to surface return flow southwards near africa is increasing. This would tend to paint a picture of the north atlantic part of the THC having some substantial changes, possibly moving further south. Decrease in Atlantic Circulation Salinity Peter Wadhams Research

Quite a good question and one you will probably get a number of different answers for. My take on it, would be that the NAO is only half of a pattern and the real pattern is the AO (Artic oscillation). The NAO is the Atlantic half of the AO and the Pacific half of the AO is substantially affected by strong El-Nino conditions. A very strong pattern in either basin can override the signals in the other basin. In this respect a strong El-Nino is likely to bias the NAO towards the positive (less northern blocking) overiding any SST tripole signal for a negative NAO from the Atlantic. Uk weather is traditonally Atlantic based, although a number of factors can combine to reduce weather from the Atlantic. I can not say that 60% of our weather is westerly ,but i would not be surprised. Of the reminaing 40% some may be northerlies or southerlies as well as easterlies. Equating easterly with a blocked pattern is a little dangerous as easterlies show high pressure to our north which can be short lived and non blocked. Sustained easterlies have been quite rare untill the last few years and these bring very cold continental air (often dry) over us.

The quoted hindcast accuracy of the Met Office's NAO forecast (between 64 and 66%) is based on the performance of the HADCM3 and GLOSEA models. 66% is a good representation of the performance of the MetOffice's seasonal forecast accuracy over the last 20 years. The metOfficeare now using HADCM4, glosea2 and HADGEM and are currently testing HADGEM2. The demeter project documentation suggests the best accuracy for a single model is currently about 81% but this was an equatorial seasonal forcast. In fact most long range forecasts covering equatorial areas are usually reasonably accurate. Demeter Project All in all I would say 70% accuracy is a fair reflection on the performance of long range model forecasts although I have a feeling the MetOffice forecasts may now be sneaking above that figure.

GFS brings it through Wednesday night into Thursday Morning. Could be a bit windy and wet over in Ireland. With A strong jetstreak comming of the US a low pressure system is likely to develop at the jet streak left exit to the north west of Helene. The trough Helene is in is being squashed and this can be seen in the flattening of Helene. High pressure looks fairly fixed over spain which leaves very little place for Helene to go. Squeezed north and absorbed looks like a good bet although with center pressure down at 964 this is still a substantial system.

My understanding about climate models is that they are tested in their ability to accurately predict previous years weather. By that I mean the model should take the conditions from the summer of 1976 and be able to predict the conditions for the following winter, verifyable by what actually occured. What tends to happen is that the models have a built in bias towards what occured over the last few years because better accuracy is obtained that way. Where sudden and dramatic changes occur then that bias can make the forecast inaccurate and there have been some notable occasions in recent years. As to the accuracy of the climate models then there is a mixed bunch of results. HADGEM2 which I think is one of the latest by the Hadley center has been shown to get an accuracy of about 90% predicting the NAO for years gone by, based on Sea Surface Temperatures ,Sea Ice extents and Snow cover. This shows significant improvements over the last few years, but it does have limitations in terms of accuracy. The average persons memory (probably not a netweather posters) about seasons does not extend back very far and winter tends to be rated in comparison to the previous winter. In this way a winter is rated warm or cold by many people almost in isolation to any underlying trends. For all the limitations of long range forecasts they become important for those who try to plan gas and electricity supplies and for those who need to buy grit for roads and organise other winter based requirements. These are areas where people work in percentages and damage limitation and where a 60/40 bias can tip a decision one way or another. Providing these decision makers can show their decisions were based on reasoned arguments they can feel reasonably guilt free if things go wrong. This may not be how things should work, but the large sums of money involved mean long range forecast are likely to continue whether they are accurate or not.

Temperatures to the north of Canada especially to the north east look high preventing ice build up. Repeated low pressure systems have swept warm air to the north of canada and ice build here is likely to be very slow. This would suggest that there may not be a persistent high pressure over the candian artic till late in the winter. This may limit the cold pooling of air over Canada, leaving cold to build up over Russia and spill out into the Pacific, giving us a strong Pacific jet again for the early winter. Canadain Coast guard is showing some melt over the last week or two. Canadian coast guard ice extents. Take from the Canadian Ice service Canadian Ice reports

Some interesting differences in the models ECMWF still takes the hurricane south as the trough extends south. Nogaps brings the reminants of Helene through much faster. Jetstream long wave is forecast by most models to firstly pick up Helene and then dip south of it allowing Helene to diminish. This relies on the forecast over the eastern US being correct with the trough lifting out. There are problems with the forecasting of this and in particular the way the GFS and CMC models are handling things. The lifting looks a little too aggressive timing wise and high pressure build over southern sattes looks a little too far north. Most models agree that Helene's core is still fairly warm and will take time to cool which seems to be in direct contrast to how the models fade Helene away. I would expect Helene's core to keep going even though Helene as a whole is turning extra tropical, this I expect will introduce an element of vorticity which should speed the long wave trough east a little quicker than forecast. I am not expecting Helene to arrive on our shores as a significant storm at the moment, but nor do I think the models are handling it very well.

We need to remember that this discussion is about the artic. Sams News Letter

The QBO also tends to affect the timing of the break up of the vortex (final stratospheric warming). An easterly phase means a late break up of vortex while a westerly phase brings the break up earlier. Details found here at Sparc

Source of the graph I provided This uses the raw GHCN Land Surface Data Available here Your first graph compares temperatures now to the average of about the last 20 years which would tend to indicate a warming since 1990 which I would not dispute. The other graph compares august temperatures for a number of years which is not the same as the average temperature for the whole year compared to previous years. My assertion is not that global warming has not taken place but on a global level warming may not have taken place in the last few years. Bearing in mind that sunspot activity has dropped away and we have been in the clutches of la nina which are known to drop global temperatures it is not surprising.

Data can often be used to show different things. Indeed the NOAA National climate data center records are generally used to show that global warming is taking place. Looking at the individual data for the last three years then the globe has cooled in the last three years. In fact there may even be a bit of a trend since 1998 for cooling. Interestingly parts of central Antartica have been cooling over the last decade as well. Neither of these facts disprove the concept of global warming but things like sunspot activity, la nina/el nino and decadal and multidecadal patterns may well mask the truth of whats going on. The fundamental fact is at this moment the NCDC data would tend to show a short term cooling, I have strong doubts whether this will continue, but the reduction in CFC's over the last 10 years may be having an affect or la nina conditions over the last years or so. Whether the concept of GW is currently a fact I am unsure but consider it extremely unwise to believe we are having no affect on climate. NSIDC Reports 19th Baltic Sea Ice looks to forming which is a little earlier than last year. Baltic Sea Ice Danish Sea Ice Page Orsted sea ice pages I think the polynya is likely to slow ice build up in the Bering Sea and Chukchi areas and seem likely to alter the AO pattern during Autumn and early winter.

ECMWF suggests Helene will not be picked up by a trough coming east and seems to stall or move slowly east decaying and then finally trundling into Spain as a rather weak feature. GFS 00Z has Helene heading directly to the south west of the UK Thursday into Friday. From Wednesday onwards it is depicted as fading almost totally away leaving perhaps some strong winds and heavy showers for some southern areas. Most models have it travelling pretty close to the azores but after that it is too early to tell.

Helene INITIAL 19/0900Z 24.4N 52.1W 100 KT 12HR VT 19/1800Z 24.6N 53.4W 105 KT 24HR VT 20/0600Z 25.1N 55.0W 110 KT 36HR VT 20/1800Z 26.4N 56.3W 110 KT 48HR VT 21/0600Z 28.3N 57.1W 110 KT 72HR VT 22/0600Z 33.6N 56.1W 100 KT 96HR VT 23/0600Z 38.0N 52.0W 90 KT 120HR VT 24/0600Z 42.0N 45.0W 80 KT This is a fairly large and strong hurricane which looks to be taking a path slightly north of Gordon. It could even make it to the UK as a substantial storm although models disagree at the moment.

Gordon INITIAL 19/0900Z 38.1N 38.7W 90 KT 12HR VT 19/1800Z 38.3N 33.6W 75 KT...APPROACHING AZORES 24HR VT 20/0600Z 38.8N 26.1W 65 KT...BECOMING EXTRATROPICAL 36HR VT 20/1800Z 40.8N 17.9W 55 KT...EXTRATROPICAL 48HR VT 21/0600Z 43.6N 8.8W 50 KT...EXTRATROPICAL 72HR VT 22/0600Z...ABSORBED BY FRONTAL SYSTEM Some storms perhaps in the south west and heavy rain in Ireland expected as the reminants of Gordon send a vorticity pulse up the frontal system.

This means that we are less likely to have a blocked pattern over the north pacific which generally means less high pressure in the Bering Strait. This being half of the AO index suggests that Pacific conditions are likely to try to change the north atlantic to the same conditions. This would perhaps indicate a bias towards low pressure towards greenland and iceland. Where last winter there was a fair amount of blocking and easterly conditions there will be a bias towards less of that this winter. This does not necessarily mean less snow but could indicate that it is likely to come from the north rather than the east. The northern hemisphere is actually quite cloudy for this time of year and according to planetary albedo rules( lots of low cloud cools the planet) this could indicate a rapid cool down this autumn and a more southerly jet during the winter (placing us on the cold snowy side more often). Repeated signals keep appearing in GFS for some quite stormy weather up ahead and it is starting to come into a reliable time frame. Very windy and Wet.

Yes those charts are out of date. I think this illustrates fairly well that graphs and explantions on the internet are not always accurate , current or in line with current thinking and what information there is may be subject to reanalysis.Version 5.2 I think is the version corrected to allow for the orbit change of the satelites amongst other things. No I did not mention the RSS or CS analysis both of which I feel in some respects are superceeded. The leading people in this area I believe are Carl Mears and Frank Wentz who I think were responsible for the RSS analysis. The latest analysis I could find is in the following link although there is some subsequent work on diurnal heating which affects the results which was published in 2005. A Reanalysis of the MSU Channel 2 Tropospheric Temperature Record I think there is one step too many in this analysis. The facts are that the species have altered on 2 continents and there is a statistical likelihood that this is linked to warmer conditions. That warming may be due to natural cycles or sunspot activity and for the large part would appear to be due to synoptic changes which may or may not be due to global warming. The link to global warming is weak and the article actually makes no mention of global warming just links the change to climate change. Similarly the second article "Diverse responses of phenology to global changes in a grassland ecosystem" mentions changes in the environment without mentioning global warming. The question for me is not whether we are affecting climate but by how much. Simple synoptic pattern changes and sunspot activity changes may account for many of the things we attribute to global warming and lead to localized climate change.Statistically it looks to me like the link between temperature and sunspot activity is very strong and could swamp any anthropological warming which makes graphs showing change open to a number of interpretations. It is also possible that those natural cycles are acting to negate the affects of global warming in which case we are grossly underestimating the affects we are having.I am not sure we have a quantifyable understanding of anthropological affects and feel surprised when others are so sure.