By Steve Goddard
There has been an active discussion going on about the validity of GISS interpolations. This post compares GISS Arctic interpolation vs. DMI measured/modeled data.
All data uses a baseline of 1958-2002.
The first map shows GISS June 2010 anomalies smoothed to 1200 km. The green line marks 80N latitude. Note that GISS shows essentially the entire region north of 80N up to four degrees above normal.
The next map is the same, but with 250 km smoothing. As you can see, GISS has little or no data north of 80N.
Now let’s compare the GISS 1200 km interpolation with the DMI data for June 2010.
Daily mean temperatures for the Arctic area north of the 80th northern parallel, plotted with daily climate values calculated from the period 1958-2002.
http://ocean.dmi.dk/arctic/meant80n.uk.php
DMI shows essentially the entire month of June below the 1958-2002 mean. GISS shows it far above the the 1958-2002 mean. Yet GISS has no data north of 80N.
Conclusion : GISS Arctic interpolations are way off the mark. If they report a record global temperature by 0.01 degrees this year, this ↑↑↑↑↑↑↑ is why.
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Straight from the horse’s mouth.
the 12-month running mean global temperature in the GISS analysis has reached a new record in 2010…. GISS analysis yields 2005 as the warmest calendar year, while
the HadCRUT analysis has 1998 as the warmest year. The main factor is our inclusion of estimated temperature change for the Arctic region.
– James Hansen
In other words, the GISS record high is based on incorrect, fabricated data. Why did Hansen apparently choose to ignore the DMI data when “estimating” Arctic temperatures? GISS Arctic anomalies are high by as much as 4 degrees, and yet he claims a global record measured in hundredths of a degree. As Penn and Teller would say …. well I guess I can’t say that here.
With this latest fantasy Hansen will likely get another quarter million dollar grant from the Kerry controlled fund.
Anthony: Why did Hansen apparently choose to ignore the DMI data when “estimating” Arctic temperatures?
.
From the DMI website:
(emphasis mine)
http://ocean.dmi.dk/arctic/meant80n.uk.php
So are you, Anthony, arguing for the inclusion of modeled data – as opposed to instrumental data – in global gridded anomaly products?
So, in the absense of data, we just make $#!t up. And then base policy off of it?
Awesome…
So, what you are saying is that GISS is bad in comparison to DMI because GISS interpolates. Mmmm, because, from your own link:
“Calculation of the Arctic Mean Temperature
The daily mean temperature of the Arctic area north of the 80th northern parallel is estimated from the average of the 00z and 12z analysis for all model grid points inside that area. ”
In other words, you jump all over GISS for using modeling to fill in the blanks, when in fact, the one you favor is also using modeling to fill in the blanks. So, what is your criteria, whichever model shows lowers temperatures is right in your book?
OK, smart guy, if the warming is only a result of the filling in of unknowns above 80 degrees, knock off both poles above 80, do the calculations yourself, and then tell us if it is getting warmer or not. If you are going to criticize a result, please post your own numbers as an alternate and explain why it is more accurate. Please show the difference and explain why it is significant.
What would be even more funny, if the GISS lit the Arctic on fire for July, when according to DMI, it appears to be one of the coldest July’s there! 🙂
Matt
DMI uses actual temperature measurements from buoys north of 80N. As far as I can tell, GISS has no data points north of 80N.
Mr Lynn says:
July 28, 2010 at 7:03 am
I would think so. America is in desperate need of science that can be depended on.
Steve,
Is it be possible to show their global depiction with all the interpolated/extrapolated areas removed (show in in Grey)? Say using a radius of 20km for the real data? I used both words because NCDC uses “interpolation” while GISS uses “extrapolation” in their product descriptions.
This might have been done before but I’d love to see it.
Keep up the good work!
The GISS interpolations (as they call it) are misrepresentations.
I call this type of data artificial. i.e. – it may as well be considered noise.
GISS has no Arctic signal.
BTW, regarding:
“If they report a record global temperature by 0.01 degrees this year, this ↑↑↑↑↑↑↑ is why.”
What makes you think they use 1200 km smoothed data when the calculate the temperature?
What makes you think any one year matters a lot when calculating the trend? It’s the media hyping up the 0.03 or whatever record; the scientists are just reporting the latest numbers.
What matters is that the earth is still hot, and hasn’t cooled any, despite the fact that we’ve been getting less energy from the sun for some years.
Are we all still keeping track of when Al Gore predicted that the Summer ice at the North pole would all be gone?
He predicted that it would be in 5 years. That prediction was made back in 2008. So keep that prediction on ice until late summer 2013.
Fingers crossed for record levels of ice in summer 2013.
Hansen is a buffoon, his once-exemplary GISS/NASA has become [as Feynman put it] a pseudo-scientific Cargo Cult immune to fact, willfully polluting everything it touches. As astro-atmospheric forces hasten towards a 70-year “dead sun’ Maunder Minimum similar to that of 1645 – 1715, Big Jim’s Green Gang of Briffa, Jones, Mann, Trenberth et al. with pilot-fish Romm and Schmidt looks ever more profoundly stupid. Just who do these coprophagic slugs think they are kidding?
Should we be using the word “interpolate” here (meaning determining a value between two data points, or are the values they derive actually “extrapolated” (meaning extending a trend beyond data points into open-ended space)? Because the two are very different. I don’t have that much problem with interpolated data, but please, extrapolated values are generally used for exaggerating a trend to support an agenda. As an engineer and scientist, I’ve seldom seen a situation where extrapolation has any value whatsoever; it is a big red flag!
I notice that there are in fact a handful of sites in GISTEMP, when you take the most complete list of stations that they have, that are above 80degree North. Those in Canada (e.g. Eureka NWT) do show 2Celsius per century warming. The 2-4 Celsius warming division (i.e. red blob) rather flatters those sites of course, since they probably only just sneak into that division. Then they have extrapolated these sites some 1000km North of course. So, they manage to give the impression that the Arctic is hotter than a furnace based on a handful of sites with slightly higher readings today then 50 years ago (and forgetting that other sites in the same climate region, and some sites quiote near to Eureka NWT like Alert NWT, don’t show similar warming).
Chris G
What matters is that Hansen is claiming 2010 to be the warmest year ever, based largely on faulty Arctic data.
“How can two different techniques show significantly different results?” – AW
Get a clue. Different instruments, different algorithms, and you expect identical results? In what way are they significantly different, other than one is a global average and the other only covers the arctic?
It is the trends that matter, and trends across all the data sets are toward higher temps.
And why does Goddard pick June?
Here
http://data.giss.nasa.gov/gistemp/maps/
Pick any time period you want and see for yourself if Goddard’s conclusions hold for other months.
Ron Broberg,
Any calculation of average surface temperature over a geographic region involves some sort of modeling. Your argument is a straw man.
The point is that DMI data uses actual buoy data north of 80N.
GISS does both extrapolation and interpolation.
Steve,
Please point me to where DMI indicates they have continuous buoy measurements above 80N. The point still stands – you’re just comparing two different interpolations in an area with sparse to no data – one from GISS, and one from DMI using model reanalysis to interpolate global temperatures.
@Ron Broberg
So, you have a problem wit what dmi does but not a problem with replacing unknown high latitude temps with known low latitude temps?
Hopefully not, because of intellectual honesty and such…
Ron Broberg says:
July 28, 2010 at 7:57 am
Anthony: Why did Hansen apparently choose to ignore the DMI data when “estimating” Arctic temperatures?
.
From the DMI website:
The daily mean temperature of the Arctic area north of the 80th northern parallel is estimated from the average of the 00z and 12z analysis for all model grid points inside that area. The ERA40 reanalysis data set from ECMWF, has been applied to calculate daily mean temperatures for the period from 1958 to 2002, from 2002 to 2006 data from the global NWP model T511 is used and from 2006 to present the T799 model data are used.
(emphasis mine)
http://ocean.dmi.dk/arctic/meant80n.uk.php
So are you, Anthony, arguing for the inclusion of modeled data – as opposed to instrumental data – in global gridded anomaly products?
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I haven’t seen anywhere where that argument has been made. The argument being made is that GISS produces a product that shows dramatic warming in areas they have little or no data, while a competing product that has more data points shows a very different trend. Even this would be minor, except that GISS explicitly claims that its superior modelling of the Arctic is the driver behind thier products showing much more temperature increase than others… when the only other product in competition has more data and different conclusions.
You’ve created a strawman to argue against.
Chris G says:
July 28, 2010 at 8:13 am
BTW, regarding:
“If they report a record global temperature by 0.01 degrees this year, this ↑↑↑↑↑↑↑ is why.”
What makes you think they use 1200 km smoothed data when the calculate the temperature?
What makes you think any one year matters a lot when calculating the trend? It’s the media hyping up the 0.03 or whatever record; the scientists are just reporting the latest numbers.
What matters is that the earth is still hot, and hasn’t cooled any, despite the fact that we’ve been getting less energy from the sun for some years.
—————————————————————
You have a number of strawmen in there. Just to address the last, but where did anyone claim that the globe hasn’t warmed? I do believe that the discussion is centered around ‘how much has the globe warmed.’
One metric (DMI) uses air temperature over the ice, while the other metric (GISS) uses SST under the ice.
Or so I’ve been told.
Does DMI produce a observational global temperature product from their weather MODEL?
If you don’t like the Arctic interpolation in GISS, then use CRU. This is the reason for the slight difference between the two. CRU just leaves the Arctic blank, along with any other empty grid cells. Given that the stations that ring the Arctic indeed are warming faster than the rest of the world, that probably leaves CRU trending too low.
Don’t the satellites also show warming over the Arctic that’s faster than the rest of the world, to the extent the satellites can cover it?
As for the reanalysis product: the ability of those to accurately describe long-term trends in the polar regions has also been questioned. After all, they also are working from sparse data, which is then fed into a model. I don’t know anything about this particular reanalysis though. But it’s a topic about which there has been some discussion in the literature. There was this recent comment and reply, for example, about polar tropospheric trends
http://www.nature.com/nature/journal/v455/n7210/full/nature07256.html
My mistaken attribution above. I should have recognized this as another Goddard post.
Steve: Any calculation of average surface temperature over a geographic region involves some sort of modeling. Your argument is a straw man.
So is that “yes” you favor using the DMI modeled data (“from 2002 to 2006 data from the global NWP model T511 is used and from 2006 to present the T799 model data are used” or “no” you do not favor using DMI modeled data.