UAH Arctic Temperature Profile

By Kip Hansen – Re-Blogged From WUWT

Arctic_alone_featuredLast week Dr. Roy Spencer treated us to the latest UAH Global Temperature Update.  Overall, the ”global average lower tropospheric temperature (LT) anomaly for October, 2018 was +0.22 deg. C, up a little from +0.14 deg. C in September”.

Dr. Spencer was kind enough to include in his post, as he usually does, a chart with the actual figures from his ongoing research.  The entire post was mirrored here at WUWT.

Here’s the part that I found interesting, which only can be seen if one graphs the data from this chart:

Various regional LT departures from the 30-year (1981-2010) average for the last 22 months are:

2017 01 +0.33 +0.32 +0.34 +0.10 +0.28 +0.95 +1.22
2017 02 +0.39 +0.58 +0.20 +0.08 +2.16 +1.33 +0.21
2017 03 +0.23 +0.37 +0.09 +0.06 +1.22 +1.24 +0.98
2017 04 +0.28 +0.29 +0.26 +0.22 +0.90 +0.23 +0.40
2017 05 +0.45 +0.40 +0.49 +0.41 +0.11 +0.21 +0.06
2017 06 +0.22 +0.34 +0.10 +0.40 +0.51 +0.10 +0.34
2017 07 +0.29 +0.31 +0.28 +0.51 +0.61 -0.27 +1.03
2017 08 +0.41 +0.41 +0.42 +0.47 -0.54 +0.49 +0.78
2017 09 +0.55 +0.52 +0.57 +0.54 +0.30 +1.06 +0.60
2017 10 +0.63 +0.67 +0.60 +0.47 +1.22 +0.83 +0.86
2017 11 +0.36 +0.34 +0.38 +0.27 +1.36 +0.68 -0.12
2017 12 +0.42 +0.50 +0.33 +0.26 +0.45 +1.37 +0.36
2018 01 +0.26 +0.46 +0.06 -0.11 +0.59 +1.36 +0.42
2018 02 +0.20 +0.25 +0.16 +0.03 +0.92 +1.19 +0.18
2018 03 +0.25 +0.40 +0.10 +0.07 -0.32 -0.33 +0.59
2018 04 +0.21 +0.31 +0.11 -0.12 -0.00 +1.02 +0.69
2018 05 +0.18 +0.41 -0.05 +0.03 +1.93 +0.18 -0.39
2018 06 +0.21 +0.38 +0.04 +0.12 +1.19 +0.83 -0.55
2018 07 +0.32 +0.43 +0.21 +0.29 +0.51 +0.30 +1.37
2018 08 +0.19 +0.22 +0.17 +0.12 +0.06 +0.09 +0.26
2018 09 +0.14 +0.15 +0.14 +0.24 +0.88 +0.21 +0.19
2018 10 +0.22 +0.31 +0.12 +0.34 +0.25 +1.11 +0.38

The graph looks like this:


Sharp eyes will notice that I have not used all the data — I graph only Global, Northern Hemisphere, Southern Hemisphere, Tropics and the Arctic.  (Leaving out US Contiguous 48 States and Australia — which I did not need and they only added clutter — each being already represented in their respective hemispheres.)

It is an interesting looking graph from several viewpoints.  Here’s what I find so interesting:

  1. There are four traces that form a cluster across the graph, being very close to one another in a band about 0.5 °C in width: Global, N and S Hemispheres and the Tropics.  The temperature anomalies from the long-term means are generally in step, but not lock-step, between regions.
  1. Except one: The Arctic.   The Arctic trace is very different from the other four.

Here is the Arctic annotated with the seasons:


The Arctic shows more variability, both quantitatively and qualitatively.

The two Arctic winters are far more anomalous than the two summers.  To me, the Arctic trace looks a bit chaotic with a seasonal overlay.  Between January and February 2018, there is a shift of 1.6 °C in the anomaly.

NOTE:  UAH’s “Arctic” is really denoted “NoPol” — North Pole — and is defined as 60N – 90N. It is not DMI’s “above 80N” nor is it “within the Arctic Circle”. It is larger than both.

The Danes have been treating us to Arctic temperature comparisons for many years.  The three years covered by the UAH graphs above look like this when overlaid on one another:


We see that the Danish Meteorological Institute has calculated the average temperatures above the 80th parallel (yes, it is a model result) and we see that Arctic temperatures have been a lot less cold than the long-term average — 10-15 °C less cold.  Even at that, Winters are running 20 degrees below freezing and Falls about 15 degrees below freezing.  The Summers, however, have not been anomalously warmer.  Summers show about 100 days of temperatures above freezing — and that by only a degree or so (never breaking above 275K — 0 °C = 273.15K)

This (painstakingly created) animation shows the DMI above 80N from 1970 thru Oct 2018.  Images sourced from  DMI’s Arctic Temperatures page.


The DMI data is in agreement with the UAH data, at least in a qualitative sense, in the last three years of the animation.  It takes a good eye to see that nothing really changes much until after 2005, when there is an oddity, then after 2010 things change even more.

The Northern Hemisphere, in the UAH data, taken as a whole, does not show this type of variation.

Now, north of the 80th parallel is a very small portion of the planet but “the Arctic”–  defined as the area inside the Arctic Circle at 66.5N — is quite a bit larger. UAH’s “NoPol” is defined as 60N-90N, is larger yet.


Both are part of the Northern Hemisphere.

For comparison, here is the Arctic Sea Ice extent long term average laid over the Arctic Circle.  The 1981-2010 average is outlined in red (I think).  You see that the 2016 and 2017 Maximum extents just about fill the long term average, with some empty space around the edges in the Bering Sea and the area north of Scandinavia.


Why show you Sea Ice Extent? — just to show that the UAH temperature high winter anomaly (north of the 80th parallel) isn’t caused by a lack of sea ice — almost all of that area is covered in sea ice in the dead of Winter.

Here is one last set of graphs, again from the DMI:


These graphs start in 1960 — about the middle of the 1945-1975 cooling period.  Globally, temperatures start to rise again in about 1980 but NOT Arctic temperatures.  DMI’s Arctic temperature (above 80 ° North) are steady, if variable, right around the long term (1958-2002) mean.  It is not until 2005 that anything exceptional begins to be seen.

So, what does that leave?  That’s what I’d like to know.  Here’s Dr. Spencer’s UAH Lower Troposphere Global (top — marked with a blue line at 2005) and that regional three year graph (bottom):


One last one, really this time.  This is UAH Arctic (UAH’s “NoPol 60N-90N” which is spatially considerably more than DMI’s “above 80N” and more area than “above the Arctic circle”):


Since the beginning of 2016 (highest spike in Arctic blue on the left), Global seems to follow the Arctic signal (which is 60N-90N) and has the same profile.  The last data point is Oct 2018. [Note:  The reference period for this graph is 1981-2010]

Here is my list of questions:  (I have no answers — and I hope the readers here can shed some light on the matter)

  1. Why is the Lower Troposphere Temperature in that circle at the top of the world, 60N-90N, behaving so differently than the rest of the world ?
  1. How much does that odd behavior affect the global record?
  1. The DMI modelled Arctic Temperature, for north of the 80th parallel, also shows anomalously warm winters and springs, seemingly confirming that there is something going on, but only since 2005.  Why is that?
  1. How is it that the DMI above 80N seasonal graphs show seasonal anomalies from 5-8 degrees, but UAH Arctic Lower Trop shows less than 1.5 as an extreme? Is there some physical measurement error in the DMI figures since 2005?  Was there some change in the measurement or model?  Or is there something physical happening (sea ice doesn’t change in the same period)?



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