It definitely sounds counter intuitive. In fact, I must admit that I didn't read the study until I heard claims of these meteorological stations being "filtered". That is when I decided to check out the study for myself.

They certainly provide an explaination for it. There are many reasons for it and they are listed in there with good explaination. For many of the most recent "drop-offs" of station usage, you will probably want to read the newer methodology that they've released which is located here (which includes satellite data as well):

http://pubs.giss.nasa.gov/docs/1999/1999_Hansen_etal.pdf 

But, the 1987 study linked to earlier goes into the process as well. Probably the biggest reason they give is margin of error. It isn't that they didn't include 7200 stations into the study (They plainly state they the data set they worked with consisted of that number of stations). It is that they've acheived the same results with 7200 stations that they have with less stations. But, by using less stations, they've acheive a far smaller margin of error.

Many stations don't report full data. Some have missing months and seasons. Some stations have only been reporting data for a few years. In order to ensure that a station's data is valid, it needs to be collecting data for a long enough time period rule out anomalies. In fact, if you look at the global region grid they work with, you can see the time stamps at which certain regions reached contiuous coverage (when there was no gap in the data for which they reported).

If you look at their most recent methodology, you can see the decline in stations used in Figure 1. Yet, even though there was a decline in stations used, the area % of the global temperature coverage achieved remains the same.

So it isn't so much that they didn't work with the full data set. They did. They achieved the same outcome whether they used all the data or only the amount they used in the final results. But, by using their methodology, they were able to give those same results with a much smaller margin of error. That is what science is all about right? Providing evidence with the smallest margin of error?

The methology also goes into how they combine the data sets from seperate adjacent stations.

The main thing to keep in mind when articles claim that they "filter" out stations of colder climates is that there is a high correlation between stations at high latitudes. The closer you get to the equator, the greater the variability between stations within 1200km of each other. The closer you get to the poles, the higher correlation between two stations within 1200km of each other. Obviously, you don't need 1000 stations within the arctic circle. It just doesn't make sense. The earth spins on a north to south axis. Therefore, the closer you get to the poles, the less variability in surface temperatures and the higher the latitude the shorter distance between longitudes. They didn't pull this out of their butts. They gathered the historical data on it and created the methodology that they've shown in their study.

You can take the study for what it's worth, but if there is anything you can say about it is that it is thorough. So, I know what you mean how it doesn't make sense that they would not include all the "numbers" in the data set. But, sometimes, for sake of leaving the smallest room for error, the full data set can't and shouldn't be used.

What was it that you felt they made assumptions on?

Clonmac:

You lost it right there.  You tried to use a 1987 study to refute something that HAD NOT HAPPENED.  So clearly I am reading your links, you are not reading mine.  How can a 1987 study talk about the 75% reduction in temperature readings that would not occur for another 4-5 years?  And how could it explain the elimination of all temperature readings north of the 65th parallel when that did not occur until 4-5 years later?  Please enlighten us on this "Karnac the magnificent" houdini of a study?

But I will let the others know so they dont waste their time on your irrelevant links.  The study does not address any of the issues raised.  Happy now?

Well, at least that is the right time frame.  Now, are they talking about this James Hansen (the one who supports the following) :

But let us take the "method" they use: "The analysis method was documented in Hansen and Lebedeff (1987), showing that the correlation of temperature change was reasonably strong for stations separated by up to 1200 km, especially at middle and high latitudes."

Ok, so what they are claiming is that every point on the globe north of the 65th parallel is within 1200 km of the one that still exists, is that right?  And that the termperature for all of california can be "derived" by the 4 stations remaining in california, right? 

Let's assume for a moment that they can do that.  What would that tell us?  That all of california's trends would have to be maintained by those 4 station's readings.  So that all of california would look homogenous on a temperature change map, right?  They have nothing anywhere else that could indicate that perhaps the Mohave was having a different temperature change than say laguna Beach.  There is no data to support a difference, just a derived temperature that rises and falls with the laguna beach thermometer.

So how does that explain the Bolivian anomoly?

How can Bolivia be undergoing a heat wave when the rest of the area is not, and there are no stations in the country?

Bolivia, a country that is mountainous and non-coastal, that is being derived by non-mountain and costal stations? How are they deriving warming with no data to support it?  What part of cooked data do you not understand?

Uh, no. As most people know, 1987 is not 1999.

Excuse me?  Show me where you debunked anything!  You CLAIM some fiction that has been shown to be a lie, but you debunked nothing.  Even hansen has not tried to debunk them, instead just hiding with his terrorist buddies!

of course not!  I have not even gotten to the part where they have a galloping adjustment to raw data.  I was saving that for another post.  But would you care to explain the galloping adjustments?  Or should I reveal more fraud with the "adjusted" data that NASA, CRU, the Met are using?

Please, I have wasted enough of my time on a religious zealot.  If you cant read, dont bother responding.

So you are bigotted against religious people?  I am sorry for your bigottry.  I feel that one's religion is their own, and should not be made a mockery of as you are doing.  But then religion should not dictate science.  Sorry for offending your bigotted views.

There is just no getting through to you.

not when you refuse to read anything other than your own dogma.  I READ your 87 and 99 reports and then re-linked to the rebuttals showing that alot of the warming trend since 1990 can be (but does not have to be since they wont let the real data stand up) attributed to the fact they are using fewer recording stations (just one of many faults) in warmer places!

You see the difference between the religious and the skeptics is that the skeptics want people to examine the papers (peer review), data and conclusions.  They want it read, tested and critiqued.  So they can find the problems and either fix them or throw them out as being invalid.  Whereas the climate fraud crew does not want any questioning, review, or inspection of their data, methods, or conclusions lest the reviews will show everyone the emperor has no clothes.

The problem is easy to see.  MF quotes one site - that does not allow dissent (comments are removed).  You rely heavily on one source - GISS.  I have shown you several (with many more should you care to ask) sites with authors from you and me, to renowned scientists (even some who co-authored earlier IPCC reports but then quit in protest because of the scam), to experts in all fields pertaining to climate science (again, it is not A dicipline, it is a convergence of several).

You have no choice but to quit.

Umm, no you didn't. Or at least you didn't understand any of it. Because if you did, you wouldn't be going on about your ridiculous "Bolivian" effect. They even talk about it throughout the study (my guess is that you skipped over that part):

One issue with the bias method is how many years of record overlap should be required for a station record to be combined with that of its neighbors. For example, it would seem inappropriate to combine the record of a station which had only 1 year in common with its nearby (within 1200 km) neighbors, because local interannual fluctuations are often as large as the long-term changes which we seek to define. For the results we present, we used only station records which had an overlap of 20 years or more with the combination of other stations within 1200 km. We tested other choices for this overlap period and found little effect on the global and zonal results. Some effect could be seen on global maps of derived temperature change; a limit of 5 years or less caused several unrealistic local hot spots or cold spots to appear, while a limit greater than 20 years caused a significant reduction in the global area with station coverage. 

and also:

We have also tested alternatives to these procedures and compared the error estimates for the alternatives, the error estimates being obtained as described in Section 5. For example, we tried weighting each box by the box area and each zone by the zone area, rather then weighting by the area with a defined temperature change. Overall temperature changes were similar with the different procedures, but the procedure as we defined it previously was found to yield the smallest errors of the alternatives which were tested. We also tried alternatives to the 1200-kin limit defined earlier; although the effects were noticeable on geographical maps of temperature trends, there was no significant effect on zonal, hemispheric, or global temperature changes.

They talk about it all through each of the studies had you care to read them. The purpose of their study isn't to create beautiful and perfect weather maps with bright colors. The purpose of their study is to find the global trend for surface air temperature (hence the name of their study). They know that sometimes the maps color don't appear realistically. But, regardless of how the map comes out, there is NO EFFECT ON THE GLOBAL TEMPERATURE CHANGES!

Seriously, you didn't read or understand it. So stop claiming you did.

And when they claimed or admitted to subjectivity, it was only for station data that was triggered as an anomaly and a decision had to be made as to whether or not the data is valid or not. If there were no triggers, then all the data was accepted. You saw the numbers for stations that were put through that subjective screening and it was less than 100 stations out of thousands.

Ya...that is why they even state this in their study:

In section 10 we describe easy access to all of our station data via the world wide web. We would welcome feedback from users on any specific datain this record.

Yup, real top secret hush hush stuff going on. Maybe if half the skeptics cared to actually look at the data for themselves, there would be less misinformation about it in the media. Because the scientists who DO look at the studies, seem to all be in consensus about it. 

After the Frog called me a pirate for saying it took a few minutes with google to find an up to date version of Sins, I wasn't exactly polite.  He didn't ban me then and he was still actively posting in the thread at the time so he sure as hell saw me do it.  I am obviously in violation of the rules, frequently.  I can't explain my continued posting priviledges.

I would also like to point out that something cannot be both true and insulting.  It may be politically incorrect, but if your brain really is dribbling out your ass, I see nothing wrong with informing you.  If you can read the bullshit I'm replying to without losing a dozen points off your I.Q. rating, then I guess you're already at their level yourself.

This thread hit rock bottom when dipshit called a standard deviation temperature graph dishonest and misleading.  When you ignore obvious inconsistencies staring you in the face, you're a fucking moron.

So where do they mention Bolivia?  nowhere.  You see I did read both (and you have read nothing) and it still does not explain how they can extrapolate with no data - differences from teh data they have!  Let me give you an example of what they are saying.

Prices of oranges and apples always go up and down by the same rate, so why track both prices.  We will track the price of oranges, and extrapolate from that the price of apples (with me so far?).

Now, 10 years later, we estimate that the price of oranges is going up 50%, but the price of apples is going up 100%.  How?  We are not talking about extrapolating the same trends, but different trends - with NO DATA!  Clearly you are not understanding what they are talking about.  They say they can extrapolate the temperature based on surrounding measurements.  Ok, I buy that.  But they did not do that.  They extrapolated different trends with surrounding temperatures with no data! 

Your problem is that I have read it, and they still fall short (we are up to 4 gates now with the IPCC report alone and you continue to use their utterances as gospel?)  You however, refuse to read anything other than what they tell you to read.  So ask them this question.  Clearly they will tell you to ignore the man behind the curtain since he is not a climatologist and does not understand the science.  Well, they are right, I am not a climatologist.  But I am a math major and know that what they are trying to do is both stupid and wrong from every aspect of basic math. So they will be wrong yet again.

They can state whatever they want. Do you want me to list the sources for their refusal to provide it?  There are more than I care to clutter up this post with, but I will do it on one condition.  YOU READ THEM.

So quit being stupid about what you dont know - i.e. if I read them or not.  I did.  But I can recognize a snow job when I see it.  Clearly if they dont know what is happening in Bolivia, they should state that, instead of claiming accellerated global warming in an area they have no data for.

IN YOUR OPINION.  And clearly your opinion is wrong, no matter how many facts are offered to show you that it is wrong.  Yes, they are using extrapolation.  But it is no less a guess than my analogy.  Clearly you did not even read your own reports if you state unequivocally that one is a guess and the other is not.  And short?  Usually journalistic pieces are, But the others came with references (did you read the links?  Thought not) that added to the analysis (why repeat what has already been printed when you can link to it?).  Perhaps if you like LONG singular reads (correction, it has links as well) you will love this comprehensive dismantling of the "extrapolation" that GISS did:

SURFACE TEMPERATURE RECORDS: POLICY DRIVEN DECEPTION?

Well, this shows me you are not doing anythingn with their data as Cygwin is just a Unix emulator.  Excel runs fine in Windows.  And excel (with macros) is all you need.

That tells me you did not read any of the links as well, as they have nothing to do with conspiracies (but then to the AGW religious, all questioning is a conspiracy!).  They have everything to do with statements and data in the primary IPCC report that broke their own rules, as these "gates" document!  Whether that was an "oops" or a concerted effort on the part of the IPCC is irrelevant in that anyone using the IPCC data and report now has to recheck the source, since the IPCC apparently cannot.

And please, if you know anything about math, please tell me what the Chi squared value of their extrapolation is?  It seems to be missing from both reports.  The only thing the reports seem to concentrate on is in verbal excuses, not any scientific analysis of the effect of their actions, or any follow up to determine if their assumptions were born out by actual circumstances. (I will give you a clue - it does not).

And finally, Bolivia is just the name given to the effect.  The effect is simply - how can temperatures be variating significantly differently where no readings are used - from the surrounding areas that are the basis of the extrapolation?  When you extrapolate, you have to have something that indicates why the extrapolation trends are different than the data points being used for the extrapolation.  You will not find that in the 2 studies you linked, because they do not address what happened after they removed the data.  But they sure tried to show that this magic occurred - which is impossible (mathematically) with extrapolated data!

Or, as you correctly pointed out with the apples and oranges, it is not an extrapolation (regardless of what they want to call it), it is a guess.  And yes, that was the point of the analogy.  You get 50% for seeing that, but 0% for realizing they are doing the same thing.

Oh lord, this is fun.  Point by point:

- where did I "make mockery" of anyone's personal religion?  Please show me.  Was it where I quoted *you* calling somebody an "AGW Religious Zealot?"  Right...I was quoting you, and you were using the 'religious zealot' part as flamebait, clearly.  (Please entertain us further by explaining that it was a compliment.)

Using this logic if I called you an idiot and you responded negatively - my next comment would be to say you were obviously prejudiced against idiots and I felt sorry for your Idiot Bigotry, lol.  As a rhetorical tactic this is fairly pitiful, don't you think?

- Religion should not color science.  I am pleased to find something we agree on.  Science has often clashed with religion where it is found that a segment of the belief system is not based on repeatable observations.

The problem here, "Dr," is that of the two of us I have centuries of repeatable observations backing me up, and all you have is an agenda and a set of beliefs which have no scientific merit, at all, even a little bit.

Luckily for you, you are embedded in a cultural subset which supports your denial, otherwise you'd probably have to examine the hypocrisy of calling anyone else "religious" as a slight

I respect your right to believe however you wish - you can believe the planet was created 4k years ago, but please don't be surprised if I get slightly peeved when you attempt to manipulate public perceptions to cast doubt on an extensive fossil record

You used a quote about religious zealotry as one of your "talking points" about the barbs being thrown.  So you are intolerant of religion?  Apparently.  I used it for what it is.  As I stated in an earlier post - relligion is not bad, but should not be mixed with science.  You apparently think that all religion is bad.  Making you a religious bigot. 

As for compliment, I dont recall going around handing out false platitudes.  Are we supposed to do that as well?  Should I add to your description - forum nazi?  OMG!  Just broke Godwin's law with that one (even though it was not perjorative, but descriptive).

And what would your "centuries" of "repeatable" data be?  nebulous enough so as not be be rebuttable, Until you actually make a statement.  But then you do suggest that I only have a set of beliefs. So tell me oracle of oracles, what are my beliefs?  Should we add karnac the magnificent to your already extensive repetoire?

I see, so now I am a creationist.  And you discovered this how?  Please enlighten me now oh omniscience one!  It seems you are the master of all - according to you.  Well thank you for your benefiscience.  We are all more enlightened now that we have had your presence among us.

So you want to get off that impossibly high ivory tower and act humble?  that might qualify you for the 3rd coming of the messiah.  But then the one fault you do not seem to disavow is your ego.

Dear Dr. Sunshine,

You, sir, are a buffoon. 

Good day,

Kestrel

Thank you for demonstrating your hypocrasy, as well as your own bigotry.  You like to pontificate, but when called on for your shallowness, you resort to name calling.  remember the 3 fingers.  You have defined yourself.

Then he again is wrong.  If you care to read my posts as well as my links, you will find a sound reasoned hypothesis that is backed up by observation and testing.  The problem with kestrel is that he cannot tolerate dissent, so as you see, he has resorted to name calling.

But clearly you suffer from a similar malady.  As he did not state an analogy or comparison, and was referring to me, then the only conclusion - short of precognition - is he was saying I was a creationist.  That does not make me stupid, just non-assuming.  You perhaps assume to much.

I love it how everyone assums omniscience.  I can read source code.  Can you? (I will not assume and you have not said).  My mother cannot.  Neither can my wife.  But that does not make them stupid or ignorant (you want a lawyer?  I know plenty that cannot read source code).

Can you debug?  What debugger do you use?  For even if you can read source code, when the source code grows to thousands of lines, it is hard to keep track of it (I know I have written enough programs to realize the value of a debugger).  So I clearly see that:

A. You assume too much - not good for a rational discussion on anyone's part - and -

B. You dont know as much as you claim to know.  But that is ok as well.  There are infinite resources to learn from out there.  Have you read the latest link yet?  Care to comment?