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Lrf And Agw Bias?

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Ok it appears Tamara and I, both feel that the MetrO are guilty of producing LRF with an AGW bias. Now despite certain members strongly denying such claims, the MetO's own website states this! So my question is, would the MetrO be better of making it's LRF based on actual findings, without the AGW bias? For me the MetO are a publicly funded company, and should be producing LRF without prejudice to their strong held beliefs in AGW!

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Ok it appears Tamara and I, both feel that the MetrO are guilty of producing LRF with an AGW bias. Now despite certain members strongly denying such claims, the MetO's own website states this!

Can you post the link to where it actually says this Solar thanks.

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Guest North Sea Snow Convection

Ok it appears Tamara and I, both feel that the MetrO are guilty of producing LRF with an AGW bias. Now despite certain members strongly denying such claims, the MetO's own website states this! So my question is, would the MetrO be better of making it's LRF based on actual findings, without the AGW bias? For me the MetrO are a publicly funded company, and should be producing LRF without prejudice to their strong held beliefs in AGW!

I have been out this evening (mercifully having a much nicer time with the rest of the human race) and read the remainder of the autumn LRF thread just now. Can't say I feel too great at all with some of the stuff that has been written. I would be able to admit some of it and say I was wrong.... if some of it was actually true!

I despair the number of times I have to repeat this but I have no problem whatsoever with people who disagree with what has been said about the METO linking seasonal forecasting with climate change via the AGW mechanism. It is not a case of refusing to read properly what is written on their website or elsewhere - it is a case of personal interpretation not being respected, and subsequently being hounded for having that interpretation. I have even been accused of heavily twisting the wording to suit my own conclusions, by someone who likes to fire a lot cr1p in my direction these days - yet when I point out the unreasonable style of this accusation and suggest that person is being rude, then a co supporter turns that around and says that I am being rude to him! And further finds offence in me simply mentioning the fact that I don't know my way around the METO environs.

It is not a case of having to admit being wrong about this issue - as someone else has rallied to me. I don't genuinely know what I have to admit to being wrong about - beyond having an opinion that for some reason some people deem I shall not have without giving blood in the process. It is not (as far as I am concerned) about being right or wrong, or being an internet debating contest to win, it is merely having an opinion and that being respected. As I have said, I don't mind one iota if people disagree with an opinion but i don't understand the need to be ground into the dust till a change of mind is forced. I even started off saying that I wouldn't be browbeaten about it, and that was precendented following previous tripe about the fact that i had opened a thread on this very subject supposedly because, allegedly, I felt I was 'losing an argument' . It clearly shows to me how little respect some people have - and it says a lot about the mentality of some people on this forum. It seems that posting on some sections on this forum is treated like a macho he-man sport by some members. Pick a gullible target and go for their throat and demand the perfect 'rebuttal' from them. 'Win the 'argument' at all cost and force someone to 'back down'. Charming. Like I say, I don't feel too great about it - amazing that complete strangers can have such an effect on your moral. Thanks a bunch.

I don't deliberately set out to end up spending half a day on a fruitless Spanish Inquistion just because I have dared to put out an opinion on something that some people think is deluded. People get paid for less. And I thought that being a catering manageress had been hard work!

I simply tried to be honest about sending e-mails to the Met Office on this subject, never imagining for a minute that it was going to be part of such a huge to-do on here. Yes they 'might' have been useful to post on here for people to see, but yes I deleted them - why would I think they would be needed? I guess I was supposed to be telepathic and have them ready for nw HQ This is a blinkin interent forum not a forensic investigation, and yet one member is questioning why I deleted them, as if it I have run away from some kind of crime scene!doh.gif This is the internet for gods sake and a crappy voluntary debate about seasonal forecasting. Who needs this grief? Where I will admit to being wrong is my own stupidity and naivety for mentioning the stupid things in the first place. Of course, probably my own stupidity for having the 'gaul' to voice the Met office/AGW affiliation in the first place.

SC - I gave my own answers to your opening question already I think as genuinely as I could in the other thread - but I don't think anyone took any notice or was remotely interested. More intent on a dumbing down mission. It is in there if anyone really wanted to know

FWIW, in a nutshell, I agree with you. Other than that I am bowing out of this now. Life is too short for this nonsense - who needs it. I really don't need a few days to reflect on what I have said as the other thread concludes - that can be taken as defiance and stubborness as much as anyone likes. Je regret rien.

Sorry that your thread has started off with my rant.

Good lucksmile.gif You might need it!

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I have been out this evening (mercifully having a much nicer time with the rest of the human race) and read the remainder of the autumn LRF thread just now. Can't say I feel too great at all with some of the stuff that has been written. I would be able to admit some of it and say I was wrong.... if some of it was actually true!

I despair the number of times I have to repeat this but I have no problem whatsoever with people who disagree with what has been said about the METO linking seasonal forecasting with climate change via the AGW mechanism. It is not a case of refusing to read properly what is written on their website or elsewhere - it is a case of personal interpretation not being respected, and subsequently being hounded for having that interpretation. I have even been accused of heavily twisting the wording to suit my own conclusions, by someone who likes to fire a lot cr1p in my direction these days - yet when I point out the unreasonable style of this accusation and suggest that person is being rude, then a co supporter turns that around and says that I am being rude to him! And further finds offence in me simply mentioning the fact that I don't know my way around the METO environs.

It is not a case of having to admit being wrong about this issue - as someone else has rallied to me. I don't genuinely know what I have to admit to being wrong about - beyond having an opinion that for some reason some people deem I shall not have without giving blood in the process. It is not (as far as I am concerned) about being right or wrong, or being an internet debating contest to win, it is merely having an opinion and that being respected. As I have said, I don't mind one iota if people disagree with an opinion but i don't understand the need to be ground into the dust till a change of mind is forced. I even started off saying that I wouldn't be browbeaten about it, and that was precedented following previous tripe about the fact that i had opened a thread on this very subject supposedly because, allegedly, I felt I was 'losing an argument' . It clearly shows to me how little respect some people have - and it says a lot about the mentality of some people on this forum. It seems that posting on some sections on this forum is treated like a macho he-man sport by some members. Pick a gullible target and go for their throat and demand the perfect 'rebuttal' from them. 'Win the 'argument' at all cost and force someone to 'back down'. Charming. Like I say, I don't feel too great about it - amazing that complete strangers can have such an effect on your moral. Thanks a bunch.

I don't deliberately set out to end up spending half a day on a fruitless Spanish Inquisition just because I have dared to put out an opinion on something that some people think is deluded. People get paid for less. And I thought that being a catering manageress had been hard work!

I simply tried to be honest about sending e-mails to the Met Office on this subject, never imagining for a minute that it was going to be part of such a huge to-do on here. Yes they 'might' have been useful to post on here for people to see, but yes I deleted them - why would I think they would be needed? I guess I was supposed to be telepathic and have them ready for nw HQ This is a blinking internet forum not a forensic investigation, and yet one member is questioning why I deleted them, as if it I have run away from some kind of crime scene!doh.gif This is the internet for gods sake and a crappy voluntary debate about seasonal forecasting. Who needs this grief? Where I will admit to being wrong is my own stupidity and naivety for mentioning the stupid things in the first place. Of course, probably my own stupidity for having the 'gaul' to voice the Met office/AGW affiliation in the first place.

SC - I gave my own answers to your opening question already I think as genuinely as I could in the other thread - but I don't think anyone took any notice or was remotely interested. More intent on a dumbing down mission. It is in there if anyone really wanted to know

FWIW, in a nutshell, I agree with you. Other than that I am bowing out of this now. Life is too short for this nonsense - who needs it. I really don't need a few days to reflect on what I have said as the other thread concludes - that can be taken as defiance and stubbornness as much as anyone likes. Je regret rien.

Sorry that your thread has started off with my rant.

Good lucksmile.gif You might need it!

It's ok Tamara, it's because some of us like to think for ourselves, instead of letting others think for us, that gets up one or two's noses on here!

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What I dont get, is why some still seem to argue with an ex-senior forecaster of the METO (with current contacts) and somebody who is studying at a high level of meteorology (who also spent time at Hadley), who have both explained the wording on the METO website, seemed to be rubbished?

I, by a stroke of recent luck, have also found someone I knew from school who currently works at the METO.

I can always ask him if need be?

There needs to be a defined line between climate change in terms of present data, and that of AGW.

Cause and effect, something I mentioned many many moons ago on another thread.

It's ok Tamara, it's because some of us like to think for ourselves, instead of letting others think for us, that gets up one or two's noses on here!

A strange comment i'm afraid. I think you'll find most, if not all, think for themselves.

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It's ok Tamara, it's because some of us like to think for ourselves, instead of letting others think for us, that gets up one or two's noses on here!

I have to take exception to that as well. The implication seems to be if we don’t think as you do then we are not thinking for ourselves, instead being lead round by the nose by others with an agenda, its that kind of attitude that entrenches opinions, stifles debate and leads to a bad atmosphere on the climate change threads. Rubbishing the views and augments of those that see things from a different view point rather indicates the paucity of your own intellect to make valid arguments. Lets stick to the facts or at least reasoned opinions about the METO forecast and not have another tribal dust up, there’s enough of that in the world already.

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Trying to get this on to the topic that you want to discuss, can someone who has the view that the meto is using AGW bias within their forecasts please explain what you mean by that, as I'm a bit wooly on what you're suggesting to be honest?

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from what ive read on met office breakdown on how they produce there lrf they seem to say they do use climate change inputs now if the world has been warming for sometime then this input is added to there computer models.

so this added heat must also be added so there for we find average to above average being the most used terms because this seem to have been what past trends have shown.

but for awhile now there lrf has become not very good although some have been totally wrong some have been a little better.

autumn 2008 and winter 2009 plus spring 2009 its been not good at all now the question is,

perhapes the reason for the added extra due to climate change maybe causing them over cooking the real outcome.

this does seem to be happening over the last few years here and there.

on thing that i would like to know is the jet stream a strong feature in there lrf this could also be another reason for there failure.

but over all it clearly states they use climate change in there lrf.

This first assessment of prospects for Winter 2009/10 is based on statistical forecasting methods. These statistical predictions are based primarily on the influence of North Atlantic Ocean temperatures on European winter weather, and changing expectations for winter due to the warming climate. In September the forecast will be updated by including output from global numerical forecast models. Seasonal trends affect large geographic areas, so our forecast for the UK is in the context of Europe as a whole.

In September the forecast will be updated by including output fromglobal numerical forecast models. Seasonal trends affect largegeographic areas, so our forecast for the UK is in the context ofEurope as a whole.

this will also have climate change inputs added to them aswell.

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Well being a fair person and quite prepared to say I'm wrong I've emailed the met office myself asking for clarification.

Very short and brief but too the point.

Good Morning.

Can you confirm a couple of things. The Long range forecasts that you issue don't factor in AGW just use the present data available to create the forecast.

The Hadley centre doesn't have any input too the long range forecast as this is done by another dept of the Met office.

Mmm just notice don't which should be doesn't. Doh.

Badboy

Onm the page I read it says the following

The same computer models of the atmosphere that are used to make the daily weather forecasts are used, with some differences:

* they are run forward in time up to many months ahead, rather than just for a few days

* active oceanic, as well as atmospheric, components are included

* they are run many times, with slight variations to represent uncertainties in the forecast process

We occasionally use statistical forecasting methods on the seasonal timescale — in winter and summer for UK and Europe. This is done where physical relationships between weather and the state of the oceans have been found, but where models do not yet show sufficient skill to pick up these particular relationships. This gives rise to a mixed statistical and physical model forecast process.

We also use this mixture of methods for forecasting the mean global mean surface temperature for a year ahead. However, on even longer time scales, such as a century ahead, only physical models are used, as no more skilful statistical approach has been found.

So we have two pages that say different things and knowing the met office this is possible or someones looking the wrong page. Strange you're looking at the winter forecast which as far as I know hasn't been released yet.

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yes i did look at the winter outlook so your right there and it would seem you have come up with some answers aswell.

but i found this which in a way contradicts :http://www.metoffice.gov.uk/science/creating/monthsahead/seasonal/index.html

this bit of the whole page catches my eye.

The slow fluctuations of sea-surface temperature (SST) can bepredicted, to some extent, at least up to six months ahead. The linksbetween SST and weather can be represented in computer models of theatmosphere and ocean. Computer models developed at the Met Office, likethose used in making both daily forecasts and long-term climate changepredictions, form the basis of our seasonal prediction systems.

so the bit ive underlined do say like those,

which is i agree different to,

are used.

but for some reason im not convinced and there pages conflict with information one saying i posted earlier that they use climate change and this post saying they dont.

but anyway there lrf is not very good and theres valid points on both sides of the fence but to recieve information direct from them so i cant argue with that.:good:

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There is some documentation from the WMO, which does not seem to indicate that the LRF used AGW model predictions in 2005, but were considering incorporation in the future. At that time:

As in previous years, seasonal forecasts to 6-months ahead have been generated each month using the Met Office’s 41-ensemble coupled ocean-atmosphere global seasonal prediction system (known as GloSea). GloSea is based on the HadCM3 climate model. A performance assessment of the GloSea system is provided by Graham et al., 2005. Operational forecasts are initialised with ocean and atmosphere conditions valid for the first day of the current month. Perturbations to the initial conditions are applied to the ocean component only and are based on 5 parallel ocean assimilations, generated through application of perturbed windstress. Additional instantaneous SST perturbations are applied at initial time to generate the 41 starting states required for the ensemble. The forecasts run on the ECMWF computing facility in parallel configuration with the ECMWF system2 seasonal prediction model as part of a developing European multi-model system (the European Seasonal to Interannual Prediction Project – Euro-SIP).

GloSea forecasts are expressed relative to a model climatology defined for each month of the year from a set of 15-member ensemble integrations initialised at the beginning of each month over the 15-year period 1987-2001. A range of forecast products are made available to NMSs, Regional Climate Outlook Fora, UK government agencies, the public and commercial companies. In 2005, a major upgrade of the Met Office seasonal forecasting web pages was released. Products now available include the following. Forecasts for anomalies in 3-month-average 2-metre temperature and precipitation, at one-, two- and three-month leads - corresponding to months 2-4, 3-5 and 4-6 of the integration. A probabilistic format is used giving probabilities for equi-probable tercile categories and also for two outer-quintile categories (20th and 80th percentiles). In addition to these probability products, maps indicating the most probable tercile category are also provided. Forecast products for monthly-mean Sea Surface Temperature anomalies in the tropical Pacific are also made available. Products may be viewed at www.metoffice.gov.uk/research/seasonal. Verification information indicating forecast performance has been generated, using WMO guidelines, and is available on the website. Verification diagnostics used include ROC curves, ROC score maps and reliability diagrams. On the website, forecasts from the GloSea system may be compared with corresponding forecasts generated using output from the Euro-SIP multi-model forecast database, which currently includes forecast ensembles from the Met Office, ECMWF and Météo-France seasonal systems. Currently Met Office products derived from Euro-SIP comprise an unweighted combination of the Met Office GloSea forecast ensemble and the ECMWF system2 seasonal ensemble.

It mentions that The European ENSEMBLES project:

In addition to other improvements, ENSEMBLES models will include, for the first time, realistic concentrations of green house gases, solar forcing and (at initialisation time) volcanic dust. The Met Office DePreSys system, designed specifically for decadal prediction, will also be included in the ENSEMBLES multi-model. In addition to the multi-model approach, alternative (or complimentary) techniques for representing model uncertainties will be investigated. In this respect the Met Office is investigating the benefits of a perturbed parameter technique in which an ensemble is generated by using perturbed versions of the CGCM physics to generate each member. The perturbed model versions are constructed by using different settings (from within a plausible range) for a number of tuneable physics parameters. The method has been previously developed and used to generate ensemble-based probabilistic predictions of climate change (Murphy et al., 2004). Initial conditions for the ENSEMBLES multi-model will be generated using improved ocean analysis techniques and observation datasets formulated as part of the FP5 ENACT project and further developed in ENSEMBLES. Techniques for representing initial condition uncertainty will also be compared. As part of the development and assessment phase of the ENSEMBLES system the GloSea model has been updated to allow realistic green house gas concentrations and volcanic dust (at initialization time), and hindcasts have been run for the 11-year period 1991-2001. Experiments using both the operational method of ensemble initialization (see Section 1.2) and a lagged start method have been conducted. The integrations are made in 9-member ensembles from May and November start dates out to at least 12 months ahead. Runs from May 1965 and 1994 have been integrated to 10years ahead. An extended1960-2001 hindcast set will be employed in final hindcast production starting in 2007.

So it would appear that the GloSea model has been updated to include Greenhouse Gas concentration variables, and I would presume, the uncertainties that are understood to be associated with that measure.

heres the link to the WMO page

But this may not be relevant to the UK long range forecast - or is it?

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Trying to get this on to the topic that you want to discuss, can someone who has the view that the meto is using AGW bias within their forecasts please explain what you mean by that, as I'm a bit wooly on what you're suggesting to be honest?

An intesting experiment, that should be statistically sound, might be to take the error rate from the MetO seasonal forecast, and see if it fits the probability density function. It should, if all is well and good, fit a pattern of equal amounts of too-warm forecast, and too-cool forecasts - as long as the sample size is large enough. Of course, we need to correct for the advances in forecasting techniques over the sample period, but that might easily (and naievely) be done by generating the function of a linear trend of the rate of improvement and using the inverse function to deduct from the forecast.

As far as I can determine, and I must admit I haven't tried particularly hard, we can only find the error rate and not what the error actually was.

If anyone has the last twenty years history, both forecast, and actual, for each season, I don't mind doing the work. And it should put this to bed one way or the other.

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Guest North Sea Snow Convection

I had believed that four main models were used in the forecasting - and one of the four models used in the seasonal forecasting is also used by/for IPCC purposes in terms of the climate element referred to on the website that goes into seasonal forecasting.

I stick to the view that within the last few years, the methodolgy has increasingly switched to reflect the assumed ongoing effects of emissions on climate as described within the IPCC reports. This means that as well as the usual data incorporated, there looks to be an increasing AGW element within the forecasting. And this is now built into the seasonal forecasting to mirror the mean IPCC projections for the near term period. Which is basically all I have set out to say, but not got that far.

The risks of this to me are obvious - we can look at the IPCC predictions for the last decade and see that thus far they are not panning out as suggested. Now of course this a long term projection by then over multi decades and as I have often said, ALL feedbacks need to be monitored over such a period to be assessed for accuracy and fair judgement. However, any short term departure from the suggested IPCC variables must surely have impacts for seasonal/annual projections if some of the same anthropromorphic data is being incorporated via a long term IPCC climate model too. On other words, it is a new form of data based within the AGW hypothesis which is more experimental and relatively untested than the other traditional methods used up till recently (perhaps around 2005)

To what extent all this is true is uncertain, but my point is that it is still worth discussing within the changing emphasis of forecasting in general and from within the strong focus, rightly or wrongly, that the METO place on AGW in terms of where our climate, and therefore the weather as a consequence, goes in the future. At some point the impact of new methodolgies will be felt. The question is, is it sooner or later?

If the METO are also trying to incorporate solar data - then this should be treated with equal caution to the anthropromophic data. The current minimum has so far been poorly predicted by the major agencies, although some notable solar scientists outside of the main organisations like NASA seem to have done better in predicting a deeper minimum. Fred/BFTP has suggested such on a few occasions of late. , Which thus far is getting closer and closer. What effect does this have on the METO forecasting wrt to their AGW bias, should the solar minimum cycle continue to confound the earlier predictions?

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Interesting link, Chris...It shows that what should be happening, really is:

The more science understands about forcings, the more that understanding gets applied to the various models...

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An intesting experiment, that should be statistically sound, might be to take the error rate from the MetO seasonal forecast, and see if it fits the probability density function. It should, if all is well and good, fit a pattern of equal amounts of too-warm forecast, and too-cool forecasts - as long as the sample size is large enough. Of course, we need to correct for the advances in forecasting techniques over the sample period, but that might easily (and naievely) be done by generating the function of a linear trend of the rate of improvement and using the inverse function to deduct from the forecast.

As far as I can determine, and I must admit I haven't tried particularly hard, we can only find the error rate and not what the error actually was.

If anyone has the last twenty years history, both forecast, and actual, for each season, I don't mind doing the work. And it should put this to bed one way or the other.

thanks for that VP-unfortunately I have no idea where you might get such data.

and to Tamara

What effect does this have on the METO forecasting wrt to their AGW bias,

I will continue to TRY and persuade you there is NO AGW bias, simply a use of CURRENT data for 1 day 1 month or even further ahead in their seasonal forecasting.

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thanks for that VP-unfortunately I have no idea where you might get such data.

I suspect the MetO have excellent records. They might be happy for someone to evaluate their skill levels, but I don't think it will be someone like me. I've just had another (free) data request turned down. I might be on the scrounge for someone with a long history of weather station data ... very soon.

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I've got 1942-1995 Finningley data then my own for Cantley(3 miles from airfield) 1997 to date.

any use?

my wind data is too low and my rainfall way too low but the temperatures are fine

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I've got 1942-1995 Finningley data then my own for Cantley(3 miles from airfield) 1997 to date.

any use?

my wind data is too low and my rainfall way too low but the temperatures are fine

I've sent you a PM, John.

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I've just looked at N-W's LRF...It's not one for the snow-lovers at all, is it?

But, I can't see how our forecast can be any more/less biased than the MetO's is alleged to be. Aren't the principles underpinning ALL numerical models the same?

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Aren't the principles underpinning ALL numerical models the same?

The principles - ie the physics are - but the implementations aren't. They can't be because, necessarily, numerical models must contain assumptions. We can see the model output of the modification of assumptions (amongst other things) in ensemble output, for instance, of GFS, and such assumptions can have a very big difference on the final forecast because weather is sensitive upon initial conditions through time (ie it becomes much more sensitive the more time elapses)

Of course, the skill level is a measure of how good those assumptions are, so, for arguments sake, let's assume that they have factored in AGW into their long range forecast. A mere hypothesis, with not much evidence, of course, but if they have, then that is indicitave that perhaps there's some skill in it. Which says a lot more about AGW than, say, whether or not we'll get snow at Christmas.

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Thanks for that, VP...

So, let's suppose that a miniscule month-by-month increase in GHG-concentrations is factored in? How would that affect a three-month LRF?

My own gut-feeling is - not much...Far less than accounting for ENSO, for example?

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So, let's suppose that a miniscule month-by-month increase in GHG-concentrations is factored in? How would that affect a three-month LRF? My own gut-feeling is - not much...Far less than accounting for ENSO, for example?

I don't think that's what's being suggested here. Reading between the lines (always a dangerous thing to do, and has got me into trouble, here, before) I think the suggestion is that the MetO are making a forecast and then, say, adding a half a degree celsius on top before publishing.

Incidentally, the idea that CO2 can be factored into a black box function so that you can put quantity of CO2 in, and it outputs a value of an increase in temperature is one of my principle objections to the CO2 hypothesis. We know weather is not linear, and the construction of such a function should be impossible (see NP complete)

Of course, this objection possibly falls down on the basis that climate can be considered a linearisation of weather over the long term, and that sort of dry discussion has no place here. My view is that when someone talks of "if you double Co2, then this is what happens" to treat with scepticism. (at the moment anyway, I'm sure some bright spark will point out how wrong I am!)

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Thanks for the link.

My brain is starting to hurt slightly, here. What if an approximation were to be interpolated from the IPCC's predicted dT/dt function: something like (5C per century/400) giving a three-month bias?

Even if that factor were to be added to model pedictions prior to publication, it wouldn't make that much difference to the result...

PS: I'm deliberatley ignoring calculus! :lol:

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Thanks for the link.

My brain is starting to hurt slightly, here. What if an approximation were to be interpolated from the IPCC's predicted dT/dt function: something like (5C per century/400) giving a three-month bias?

Even if that factor were to be added to model pedictions prior to publication, it wouldn't make that much difference to the result...

PS: I'm deliberatley ignoring calculus! :lol:

Well the proposed function must establish dT/dC (where C=Co2 quantity, and T is temperature) and then partially differentiate it with respect to t (time) Of course, the IPCC don't publish that sort of thing because there's no need - it's written for governments, not scientists, but I suspect it's lurking in some paper, probably published at the start of the 20th century. I've looked, but I've never found it which, of course, doesn't mean it's not there. It's the dT/dC thing I have a problem with. I read somewhere that the rate of change is related to the power law, but can't find the link.

Anyway, if I were to bias a forecast - and I find nothing wrong with putting a bias in; people often treat the two words {bias,evil} as synonyms, and they're not - I would generate a trend line, get the equation (in the form of y=mx+c) and then modify the temperature, y, according to time, x with respect to m, and c. That'd do the job.

Yes, you are quite right that if one were to do it in such a fashion as this, then the changes would be miniscule, which is sufficient with the CO2 hypothesis (CO2 will build over time) but if one took a local maxima trend and a distant minima trend (so two coordinates on the Cartesian plane (x,y) where the t is very low, and (x,y) where t is very high (1998?)) then your trend line would be steeper and the adjustment more. There is a rational basis for doing it like this, and the main one that comes to mind would be establishing an error basis for the final forecast (ie figuring out the dimensions of the football field before you draw the centre circle) Of course, by taking the recent maxima trend you are pre-conceiving an ever warming world....

Using an infinite amount of data presented over an infinite amount of time, might mean such AGW bias (recently) should be regressed to the mean. Since it's been warm recently, that would mean that output should be decreased accordingly. Perhaps, of course, that is what happens, the guys at the MetO know that, so they artificially increase the temperature to account for said regression.

For all of that, unless we get hold of their methods, their data, or someone talks about it in public, we'll never know, and it's all pure hyperbole and guesswork.

Unless we can get the data to see if there is any warm bias, somewhat like I suggested previously.

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A little more research on the GLOSEA product from which the (UK and anywhere else they want to sell their products) seasonal forecasts are taken, has come up with the following from the Met Office:

PREDICTION OF THE GLOBAL TEMPERATURE ANOMALY FOR 2009 USING DYNAMICAL AND STATISTICAL METHODS

Chris Folland & Andrew Colman, Met Office Hadley Centre

FORECAST ISSUED DEC 30 2008. A PRESS RELEASE is on http://www.metoffice.gov.uk/corporate/pressoffice/2008/pr20081230.html.

I found it HERE. I had to log on to the Science section for seasonal forecasts, so this link may not work. PM me if you have difficulty.

It clearly states that volcanic, Solar and Greenhouse Gas forcings are being incorporated in the model:

1.1 PREDICTORS USED IN THE EMPIRICAL METHODS

The six predictors listed below have been identified by more than one author to be related to large-scale temperature:

a) ENSO HF1: The High Frequency El Nino Southern Oscillation sea surface temperature index 1 (ENSO SST HF 1). This is the time series of the first covariance eigenvector of high frequency (<13 years) global SSTA for 1891-2005 in Parker et al (2007). This eigenvector pattern is related strongly to ENSO.

:rolleyes: IPO: The Inter-decadal Pacific Oscillation (IPO), the quasi-global manifestation of the PDO. This is used in the form of the time series of the second covariance eigenvector of low frequency global SSTA for 1891-2005 as described in Parker et al (2007). This is a small factor and replaces previous use of the Atlantic Multidecadal Oscillation which is not statistically significant in current models.

c)VOLCANO: An index of global volcanic dust cover (VOLCANO) produced by Sato et al (1993). Dust veils from major volcanic eruptions, particularly in the tropics, lead to a significant drop in global temperature for a year or two after the eruption.

d)SOLAR: An index of solar irradiance (SOLAR) as supplied by Lean (Frohlich & Lean, 1998) and extrapolated to the present. A small downward adjustment has been made to the figures for 2006,2007 and 2008 to place 2008 at the bottom of the solar cycle. Latest observations on http://www.dxlc.com/solar/solcycle.html show the latest solar minimum trough to be 18-24 months later than expected from the Lean predictions.

e)GSO: An estimate of the global mean anthropogenic net radiative forcing at the tropopause. This comes from changing concentrations of well-mixed anthropogenic greenhouse gases, the direct and indirect effects of sulphate aerosol emissions and from tropospheric ozone concentration changes (GSO).

f) GLOSEA NINO 3.4: Predictions of the Nino3.4 area (170-120oW, 5oN-5oS) SST anomaly made by the Met Office GLOSEA coupled ocean-atmosphere global circulation model are used to replace the current observed ENSO state as measured by predictor a), observed ENSO HF1, to make a second forecast.

GSO forcing is now the average of the forcings appropriate to the IPCC Fourth Assessment Report (2007) B1, B2, A2 and A1F1 scenarios. It is expressed as the annual mean forcing at the top of the troposphere in wm-2 . This represents only a small change from the previous forcings used to calibrate the models since 1947. Experiments show that the best fit to the observed surface temperature data since 1947 is to use the value for the previous full year. Predictor data for the following periods are used.

ENSO HF1 October-December 2008

VOLCANO December 2008 (extrapolated from data ending in 1997 assuming no

significant recent activity)

SOLAR January-December 2008

GSO January-December 2008

GLOSEA NINO3.4 index. January-April 2009 forecast (used in place of ENSO HF1 )

The predictor periods were chosen to extract maximum skill from data available at the time of the forecast.

However, in variance to what the WMO report I quoted in an earlier post said, these forcings were used as long ago as 2000 in the GLOSEA model, as this 2000 report states:

1.1 PREDICTORS

The six predictors selected and listed below have been identified by more than one author to be related to large-scale temperature:

a) The Inter-Hemispheric Contrast (IHC) index which is the time series of the second covariance eigenvector of low frequency global SST for 1911-1995 in Folland et al (1999). This index is also highly correlated to rainfall in the Sahel on decadal time scales.

:unknw: The High Frequency El Niño Southern Oscillation index 1 (ENSO HF 1) is the time series of the first covariance eigenvector of high frequency (<13 years) global SST for 1911-95. This eigenvector pattern is clearly strongly ENSO related.

c) The High Frequency El Niño Southern Oscillation index 2 (ENSO HF 2) is the time series of the second covariance eigenvector of high frequency (<13 years) global SST. This eigenvector pattern is also ENSO-related, but the time series is 6-9 months out of phase with HF ENSO 1. These patterns are also in Folland et al (1999).

d) An index of global volcanic dust cover (VOLCANO) produced by Sato et al (1993). Dust veils from major volcanic eruptions, particularly in the tropics, lead to a significant drop in global temperature for a year or two after the eruption.

e) An index of solar irradiance (SOLAR) as supplied by Lean (Frohlich & Lean, 1998).

f) An estimate of the global mean net radiative forcing at the tropopause from well-mixed anthropogenic greenhouse gases, the direct and indirect effects of sulphate aerosol emissions and from stratospheric and tropospheric ozone concentration changes (GSO). This index was calculated using the Hadley Centre’s current Coupled Ocean-Atmosphere general circulation model, HADCM3. It is expressed as the annual mean forcing at the top of the troposphere in wm-2 (Johns, personal communication).

g) In one of the of the forecasts, predictions of the Niño3.4 area (170-120oW, 5oN-5oS) SST anomaly made by the NCEP coupled ocean-atmosphere global circulation model (NCEP NINO3.4).

Over the jackknife testing period, 1949-1998, our knowledge of the state of the North Atlantic Oscillation in the current year did not add skill. Tests also showed that the current state of the Interdecadal Pacific Oscillation added no interannual skill over and above that of ENSO. We chose this period because the predictor and predictand data are best

then, though in the near future, current advances in data set analysis might allow this period to be substantially extended.

Predictor data for the following periods are used. The examples given are for the prediction for 2000 IHC September-November 1999

ENSO HF1 September-November 1999

ENSO HF2 September-November 1999

VOLCANO November 1999

SOLAR January-December 1999

GSO December 1998 - November 1999

NCEP NINO3.4 January-June 2000 (used in place of ENSO HF1 )

The predictor periods chosen were selected to extract the maximize available skill from data available at the time of the forecast. Note that for the observed predictors, use of predictor values simultaneous with the forecast in the training equations did not produce more than a marginal increase of skill. Use of such predictors in real time would also involve estimating them in the year ahead. So only observed predictor values are used, except for the small annual SOLAR radiation index which can be estimated quite accurately for the current year. So far, no lags have been introduced into the radiative forcing data predictors other than an effective lag of about one year due to the choice of predictor values

that centre on middle of the year prior to that being predicted. This will be investigated in future.

I guess the estimate of "skill" refers to hindcasts made by the model on various runs with and without the predictors, with various adjustments made to each to achieve the best result.

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