By Steven Goddard
As discussed in my last post, GISS claims to have better Arctic coverage than Had-Crut, and uses that as an explanation of why they are trending upwards when Had Crut isn’t.
“A likely explanation for discrepancy in identification of the warmest year is the fact that the HadCRUT analysis excludes much of the Arctic ….. (whereas GISS) estimates temperature anomalies throughout most of the Arctic.”
In this post, I will show a number of things wrong with that claim. GISS uses the maps below as evidence of their better coverage.
The problem is though, that GISS actually has very little Arctic data. The “GISS 2005” map above uses 1200 km smoothing (which assumes that the weather in London somehow affects the weather in Monaco.) If we look at the un-smoothed GISS data from 2005 (below) we see something very different.
GISS actually has very few temperature readings in the Arctic. much less than Had-Crut. The map below shows the differences in coverage. Areas where Had Crut has better coverage are shown in green. Areas where GISS has better coverage are shown in red. Note that Had-Crut has more extensive coverage than GISS on almost every continent.
Now, let’s look at some of the specific problems with the GISS smoothing in the blink map below, which alternates between Had-Crut and GISS 2005 data.
- GISS completely missed a cold area north of Svalbard. They show that region several degrees above normal.
- GISS has almost no coverage in the Canadian Arctic
- GISS has almost no coverage in Greenland
- GISS has no coverage in the Chukchi Sea or Arctic Basin
- GISS has very poor coverage around Antarctica
- GISS has very poor coverage in Africa
- GISS missed large regions of below normal temperatures in the southern oceans and Antarctica
Now, let’s compare GISS Arctic coverage with UAH, below. Note that UAH has much better coverage at both poles than GISS (as well as everywhere else.)
![[Image]](https://i0.wp.com/discover.itsc.uah.edu/amsutemps/browse/AMSU_A_15.latest.a_04.png?resize=531%2C283&quality=75)
Conclusion: GISS implications that that they have better Arctic coverage than other sources are simply untrue. They have very little actual data near either pole, and their extrapolations in those regions are demonstrably poor.
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Phil.
The UAH maps do show latitude/longitude and they clearly show the cutoffs at the poles.
http://discover.itsc.uah.edu/amsutemps/AAT_Browse.php?chan=1&satnum=15&aord=a
stevengoddard says:
May 18, 2010 at 12:06 pm
Bob,
I hear you, but it still looks to me like Had Crut has better coverage.
http://docs.google.com/View?id=ddw82wws_635ftj7fzgc
GISS doesn’t have any “coverage” of its own, it uses existing temperature records which it then processes to give a best estimate of the global temperature anomaly for each month and year. Since it’s main business is climate models which definitely do make predictions for the Arctic and Antarctic, places which are hard to measure (even with satellites – the well known “pole holes”), they use best-guess techniques for estimating temperature anomalies. Not temperatures.
HadCrut can simply say – “we don’t measure that area”. Indeed. Look at their monthly data in text format:
http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3vgl.txt
See the second line of every year ? For example, 1998:
1998 0.486 0.739 0.520 0.608 0.570 0.579 0.651 0.616 0.400 0.409 0.342 0.424 0.529
1998 81 82 81 79 80 78 79 79 78 79 79 80
Their data format is:
Hemispheric/global average data file format
for year = 1850 to endyear
format(i5,13f7.3) year, 12 * monthly values, annual value
format(i5,12i7) year, 12 * percentage coverage of hemisphere or globe
Coverage of 0 means data not yet available
Hence, every month shows the percentage coverage of hemisphere or globe. The Jan temp. anomaly was 0.486° C, and this was for 81% of the globe. Apr had a temp. anomaly of 0.608° C over 79% of the globe, etc.
When HadCrut says 1998 is the warmest year, with a temperature anomaly of 0.529° C, they mean for less than 80% of the surface of the Earth (79.5833% average coverage that year). Since the Earth has a surface of 196,940,400 square miles, that means HadCrut just ignores 40,208,730 square miles. No “best estimate” – just give this 20% of the Earth’s surface the global average for that month, or that year.
That’s what they are doing when they say 1998 had a global temperature anomaly of 0.529° C (relative to the 1961-1990 climatology). They are infilling the masked area with the global average for that year – which, these days, is too low for the Arctic.
http://www.columbia.edu/~jeh1/mailings/2010/20100115_Temperature2009.pdf
Look at Figure 3 in this Hansen paper – the only reason GISS “best-guesstimates” gridboxes that have no data by using nearby gridbox data is because that’s a better guess for temperature anomaly than global average anomaly – which is what HadCrut does, when giving global temperature anomaly results.
GISS needs a best estimate of entire, global temperature anomalies each year – HadCrut just ignores 1/5 of the planet, and “estimates” that the temperature anomaly there is the same as the average for the entire planet.
JohnH says:
May 18, 2010 at 11:12 am
That would explain the back to average ice extent then ?
Yes, due to rapid global warming, the Arctic sea ice is back to the 2007 average:
http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
And poised to drop below.
stevengoddard says:
May 19, 2010 at 9:07 pm
Phil.
The UAH maps do show latitude/longitude and they clearly show the cutoffs at the poles.
http://discover.itsc.uah.edu/amsutemps/AAT_Browse.php?chan=1&satnum=15&aord=a
No, that is a NASA Marshall Flight Center map not the UAH map which is shown below:
http://climate.uah.edu/maps/1208big.jpg
Phil,
What part of “uah” is it that you are not seeing in this url?
http://discover.itsc.uah.edu/amsutemps/AAT_Browse.php?chan=1&satnum=15&aord=a
Anu,
I would describe it as a “worst estimate.”
Hi Anthony,
Could you add the error bars, to see if they match ?
I mean as both data sets are global average temperature, they should match if uncertainties were appropriately calculated.
stevengoddard says:
May 19, 2010 at 11:21 pm
Phil,
What part of “uah” is it that you are not seeing in this url?
http://discover.itsc.uah.edu/amsutemps/AAT_Browse.php?chan=1&satnum=15&aord=a
So they have linked to the NASA Marshall Flight Center map (What part of the “NASA-MSFC” logo is it that you are not seeing?) The UAH map which you also linked to looks like this:
http://climate.uah.edu/maps/1208big.jpg
Note the URL and © statement, this is their post processed data which allows for drift etc. and appears to infill the polar regions (within the limits imposed by the previously described poor mapping). Had UAH presented their data as professionally as NASA-MSFC and RSS there would be no problem, but they don’t.
stevengoddard says:
May 19, 2010 at 11:22 pm
Anu,
I would describe it as a “worst estimate.”
Faulty estimates of Arctic warming lead to faulty estimates of Arctic sea ice melting.
http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
Does anybody know how north pole and south pole are defined for the UAH temperature departure list?: http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt. North pole had a new record in april 2010. South pole with no data south of 70 °S and north pole without data north of 82.5 °N … so maybe Chicago belongs to north pole???
Nevertheless the UAH list is much better than the CRU list without any descriptions:
http://www.cru.uea.ac.uk/cru/data/temperature/crutem3gl.txt
Climate Kate says:
May 20, 2010 at 10:34 am
Does anybody know how north pole and south pole are defined for the UAH temperature departure list?: http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt. North pole had a new record in april 2010. South pole with no data south of 70 °S and north pole without data north of 82.5 °N … so maybe Chicago belongs to north pole???
But as you will have noticed Steve is determined not to acknowledge that.
Nevertheless the UAH list is much better than the CRU list without any descriptions:
http://www.cru.uea.ac.uk/cru/data/temperature/crutem3gl.txt
Although on their index page they do give you a key, more clearly than the titles on UAH (Npol doesn’t tell you that it’s 60ºN-82.5ºN for instance).
“Hemispheric/global average data file format
for year = 1850 to endyear
format(i5,13f7.3) year, 12 * monthly values, annual value
format(i5,12i7) year, 12 * percentage coverage of hemisphere or globe “
This kind of bickering and pissing match is strictly unproductive. What is the argument or the issue? Why don’t you “define the problem” and then address it? I am a scientist, but I’ll be damned if I’m going to dig into the data to see what this post finally devolves to. I suspect a whole bunch of non-scientists turned this one off a long time ago. That’s beginning to be an issue here – several people putting up data without any clear explanation of what it supposedly means, then the discussion degenerating into multiple posts of one link after another with yet more date with no attempt to answer one another’s questions. That’s a sure prescription for failure.
Does anyone else see the irony that GISS stands for “Goddard Institute for Space Studies”?
Any relation, Steve?