DMI polar data shows cooler Arctic temperature since 1958

PN says:
August 7, 2010 at 5:10 pm

1) What is the special significance of daily average temperatures above 0 degrees C? Sea ice melts at -1.8C, and melting would presumably begin when this temperature is exceeded at some part of the day (while daily averages are still below -1.8C). The only effect of this limit seems to be to restrict the analysis to approx 1/6 of the total data without any basis in nature I can immediately think of.
2) What was the exact methodology used to produce the graphed values? It’s all good and proper to blast climate scientists for “hiding their data and methods”, but here we get absolutely zero on the methodology used, apart from the somewhat spurious 0C limitation.
Looks like a pretty crude case of cherry picking. The warming trend in the remaining 5/6th of the data left out is quite strong, when you look into it.

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Each paragraph in your attempted rebuttal is incorrect:
Given an unbiased, “uncorrupted (er, un-corrected) daily Arctic temperature record at 80 deg Latitude spanning every day from 1958 through 2010, there are two temperature trends of interest: Average summer temperature and average winter temperature. The spring and fall merely “connect” the two extremes, and display absolutely interesting data.
Certainly, one could choose -1.9 degrees as a cutoff, but the meaning and conclusion of the data is not changed: Average Arctic summer temperatures at 80 deg north have fallen consistenly and steadily since 1958 while CO2 levels have steadily increased. Therefore, Hansen theories of catastrophic Mann-made global warming are false.
Daily “Winter” temperatures over the same period have increased slightly over the same period, but do NOT confirm CAGW theory, because NO PART of Hansen/IPCC/Gore’s theory allows for ANY decrease in Arctic temperatures at all during any period of the year.
Further, Hansen’s much-corrupted/distorted and mannipulated claims of extreme Arctic heating are also disproven mby this data: He CANNOT claim a 4 degree Arctic rise since 1970 if actual temperatures have fallen steadily since 1958, and if regional 80 deg Arctic temperatures have only increased slightly over the whole period. Thus, Hansen’s projection of 1200 km land temperature trends out over the arctic sea based on his 56% correlation in a single 1987 paper are also proven wrong.
The methodology of the “graphs” is simply. One plots the temperature of selected days over time. (In this case, the records are for those days when the avaerage temperature since 1958 has been greater than 0.0 C. Convenient enough cutoff date for our purposes. You imply that if a part of the day is above -1.8 C, then sea ice wll melt – but not large masses nor would such 5 or six “added” days change the long-term trend of a cooling arctic summer temperature.) DMI’s data was publicly read from publicly-provided available records from DMI daily records, and cannot be refuted or corrupted or manipulated. Nor can be “wished away” or casually waved away. (Actually, sea ice melts from underneath because the water melts the ice, not the air. The freezing air creates the ice, but not substantially contribute to melting trends. (Based on a MAX observed air temp of +2 – +3 degrees in the area, and a 1000x higher heat transfer rate and heat capacity between air and seawater.)
You complain of limting the trend check to 1/6 of the year, but actually, we are looking here at a widely varying (high standard deviation) low period greatly below the freezing point of water through the winter (one long flat part) and a second, slightly shorter period when the air temperature is above freezing: also along a flat, almost linear period of the curve. So your complaint is incorrect: We ARE looking at both sides of a sinusoidal record (maximum and minimum points each year) and both sections of the curves (maximum and minimum) are roughly the same length. So we are looking not at 1/6 of the data, but at ALL of the data that can be analyzed. Once a consistent, 60 year trend in the maximum (and minimum!) points in the sinusoid is established, the “trend” in the fall and spring is meaningless.
You however, would appear to prefer that we use an annual “average” value so the winter rise “hides the decline” in summer temperatures.

Method & attempt at recreating;
I asked about your method in producing the graph, as I was unable to reproduce the results. Using the data provided by Moriarty and simply calculating for each year the sum of all temperatures above 273.15 K divided by the number of such data points provides this outcome;
http://i25.photobucket.com/albums/c69/Nuveena/Strategy/Recreation1.jpg
As you can see, the graph tracks yours quite closely with the same “dips” and “rises”. However, it does not show such a strong downward trend towards the end as yours. I was unable to find the exact method you used, I fear, so can’t draw any real conclusions about this difference. As you can see, I also calculated the best linear fit to the data I had available and it shows a very marginal cooling for the so called “melting season”, only 0,1K over 50 years. This is likely not a strong enough trend to be statistically significant.
The 0C choice;
In order to show why I think the choice of a fairly arbitrary temperature cutoff point followed by a calculation of an average I constructed a synthetic (exaggerated) data set to illustrate my point;
http://i25.photobucket.com/albums/c69/Nuveena/Strategy/Illustration1.jpg
Clearly, the “fast” curve would end up producing a far higher average daily temperature above the 54C cutoffline compared to the “slow” curve.
The picture clearly shows the weakness of the method you have chosen. If we maintain the temperature of our sample above the ambient (0C) temperature in my synthetic example, we very clearly expend a lot more energy than if we bring the sample to a brief, high, temperature.
So, unlike the poster above maintains, the full curve is what matters and the “slopes” aren’t simply lines that connect the dots. The total energy of the system is determined by the full area under the curve and not by some semi-arbitrarily chosen segment of it. Now, let as have a look at the data provided by Moriarty to display this in practice.
Decade binning;
I chose a simple method, calculating the average half daily temperature over 5 10 year bins for each half day in Moriarty’s data. (Sum temperatures for day 0.5 over 1958-1967, divide by 10. Repeat for all days as well as for 1968-1977 etc). I’m not an expert in the fields of meteorology or polar research so the choice of 10 year bins is simply based on; the data set is approx. 50 years long and it is hard to try and understand a graph with too many curves, so a limit of 5 X 10 years seemed logical. Plotting all the 50+ yearly graphs on top of each other would just have been confusing so some sort of binning seemed to be in order. The result should be illustrative, though it certainly lacks scientific power of proof.
http://i25.photobucket.com/albums/c69/Nuveena/Strategy/Illustration2.jpg
Even though my method is a bit crude, it goes to show how minute the changes are in the summertime over the 1958-2007 period and how noticeable the warming in the wintertime is.
“Melting season”;
Finally, you are making the claim in the original post and the replies later on that the melting of arctic sea ice towards the end of the priod is not due to warming of the weather and submit your, as I have tried to show, flawed method to show it would allegedly have become cooler in the artic during what you term the “melting season”. As I’m not an expert in the field I cannot offer a full dissection of this topic but there are a couple of fairly obvious points which quite clearly argue against your claims;
1) As I stated before, you have not chosen the correct melting/freezing point for saline sea water which is -1.8C and not 0C.
2) The temperature data from DMI is an average over the latitudes from 80 degrees to 90 degrees. However, the melting of the ice does not take place evenly, it mainly takes place at the edges of the ice cap. If you would want a sort of an analogy, you could consider Miami and Washington DC, which are about 10 degrees apart. The actual melting would take place in “Miami”, but the average temperature between the two towns would be somewhere in “North/South Carolina” when in fact you would be much more interested in the temperature data from “Miami”. The effect of this is that the actual melting of sea ice begins at a far lower mean temperature than even #1 implies, in fact as soon as temperatures and sunlight at the edge of the ice cap allows for melting.
Both of these effects means the actual melting season, if we define it as the time of he year the polar ice cap begins to shrink is quite certainly much longer than what you limited your graph to express. How much longer, I just can’t say. What is clear though, is that knowing the real length of this season would be important to draw any conclusions of the data.
And that’s another important point, as my synthetic data illustration displays, the number of melting days is very important. One day at +1 C simply does not melt as much ice as, say, 50 days at +0.5 C, something you just chose to ignore in your analysis by removing the time dimension and only focusing on the temperature dimension.
I’m really sorry, but nothing I have seen here so far can convince me that the analysis is to be taken seriously. There are a number of very basic flaws which any first year university student would be able to catch in your methodology and your reasoning. And the claims you make are completely beyond the scope of your analysis.
Oh, and I don’t maintain a website.

Petter Nikula
Thanks for your work.
I found a rather significant downtrend in these Acrtic data from 1993 and foreward. Sod do you:
http://i25.photobucket.com/albums/c69/Nuveena/Strategy/Recreation1.jpg
Then you speak of “only 0,1K downtrend from 1958 and foreward. This is not in contrast to my findings as I dont mention quantitatively a specific trend 1958 and foreward. So how can this be showing me wrong? I just said that some recent values are colder than anything seen in the beginning. Thats why i got puzzled and checked things out.
By the way, 2010 may give an all time low.
I can see that the results from some of the latest years are different, and it would be nice if DMI just showed the exact numbers in stead of reading pixel for pixel as I did.
But Petter: You seem much more interested in finding some flaws in what I did rather than focus on the really really interesting here: We have heard that the Arctic is warning faster than any where else, largely based on (STUPID) measurements taken from land stations. And then both your and my reading shows this to be far from the whole picture (!)
But all you care about is your claimed “faults” by me ?
The climate debate is truly odd.
And then your last comment “Oh, and I don’t maintain a website.”
Whats that all about, Petter? Whats going on?

Update:
http://hidethedecline.eu/pages/posts/colder-arctic-melt-season-temperatures—prognose-2010—6-days-to-go-189.php
includes an example of how I obtain data, quite simple.
K.R. Frank Lansner

It will be interesting to note that shortly (15-20 years, if the latest Arctic summer cooling trend holds) that there will actually be “no” melting season at all, and that summer Arctic temperatures will never exceed 0.0 C.
If so …. Is “that” the tipping point that slides us over into the long-overdue next Ice-Age?
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UPDATE: 14/8 Estimate now 0,365 C after DMI has updated. Coldest (by far) on record so far.
3 days to go for 2010 DMI melting period average temperature.