Watts Up With That?
Aug 7, 2010
From Frank Lansner at Hide the Decline
From DMI (Danish Meteorological Institute) we learn, that Arctic 80N-90N temperatures in the melt season this year is colder than average. This was the case last year too, while earlier years in the DMI analysis period (1958-2010) hardly ever shows Arctic melt season temperatures this cold.
This is how DMI temperature averages for Arctic 80N-90N melt season appears when plotted to allow compare over time:
Fig2 (When i speak of “the melt season” i refer to the period where temperatures 80N-90N are above zero Celsius. The green line above is the DMI temperature average, a little over 0,9 Celsius)
It seems that average Arctic temperatures 80N – 90N in melt season of the years 2004, 2009 and 2010 are around 0,4-0,5K whereas the temperatures in 1991 and 1993 where around 1,3 K. In general DMI´s data (if correct) reveals a cooling from the mid 1990´ies till today.
The 80N-90N area of the Arctic is practically always ice covered. Therefore, the 80N-90N is perhaps not so affected by heat from the other areas of the Arctic that has been still more ice free in the period 1995-2007. Im not sure why DMI shows such a cooling trend for the 80N-90N area, but it could appear as if the ice covered areas of the Arctic has its own history of temperatures? And how should GISS data from distant land stations account for this?
Here´s how GISS temperature appears when comparing 1991 to 2009 for the Arctic Polar region:
The Arctic melt season is mostly June and July. For both months the GISS Arctic temperature trend 1991 vs 2009 shows warming around 0,3-0,7K which is in contrast with the DMI trends of cooling of around 0,7K for the region.
Is it basically a convincing idea to use land/city/Airport temperatures for temperatures at sea? Give it a thought:
Imagine you stand on a boat 12 km from land…
You want to know the Air temperature in 2 meters altitude. Which temperature would be most precise, the water temperature around the boat or the temperature from land ( measured at the city airport… ) ?
Now imagine the same situation, but this time you are 1150 km from land. Which temperature would you rely most on, the water temperature around the boat or the temperature from land (city/Airport) 1150 km away?
Since 1987, James Hasen, and thus GISS, har used a 1200 km radius in their global temperatures based on meteorological stations and thus extended land temperatures to cover a considerable ocean area.
Below a compare of SST with the temperatures GISS use for ocean areas.
1) Left: GISS land temperatures including land temperatures to cover ocean areas.
2) Right: As 1) but now for the ocean areas the actual SST measured by the Hadley centre are shown.
Both pictures are from july 2010. From this illustration we see, that ocean areas represented by SST are poorly reflected by GISS land temperature data and the idea of expanding land temperatures to cover ocean area appears challenged?
Read the entire article at Hide the Decline
This article was posted: Saturday, August 7, 2010 at 3:16 am