Comments on: What Is Normal Arctic Ice Extent?

By: Phil.

Phil. — Sat, 02 May 2009 17:01:11 +0000

pkatt (16:56:10) :
Pardon me, but on cryosphere arent we seeing the same weird stretches of open water we were when the satelites were screwing up?

No.
http://arctic.atmos.uiuc.edu/cryosphere/NEWIMAGES/arctic.seaice.color.000.png

By: pkatt

pkatt — Fri, 01 May 2009 23:56:10 +0000

Pardon me, but on cryosphere arent we seeing the same weird stretches of open water we were when the satelites were screwing up? How is it we can trust the data we are getting?

By: bill

bill — Fri, 01 May 2009 12:42:49 +0000

Earle Williams (20:15:13) :
Not sure why I wrote radar! but thanks for the correction.
On this page the sledge pulled electromagnetic (EM) induction sounding device is compared against bored holes. There are still errors of over a metre shown.

http://www.awi.de/en/research/research_divisions/climate_science/sea_ice_physics/subjects/ice_thickness_measurements/

By: M. Simon

M. Simon — Fri, 01 May 2009 11:21:48 +0000

Shouldn’t the ice be above normal given the lull that the Sun has been in and the low(er) temperatures experienced across the region this past winter? It seems weird that given those factors it’s still below the average.

Things take time to heat up and cool off. Big things take longer.

Heat transfer in a nut shell.

By: Earle Williams

Earle Williams — Fri, 01 May 2009 03:15:13 +0000

bill,

Neither of these instruments use radar. The graph you refer to compares thicknesses calculations for the airborne vs. the “ground based” electromagnetic conductivity instruments. There is no ice auger thickness to decide if one or both of the measurements are in error.

The size of the EM bird vs the ground based EM31 account for some of the observed difference. One is measure thickness over an approximately 2 m diameter circle whereas the other is measuring thickness over a 4 m diameter circle. Variance between the two instruments is to be expected.

The good correlation with EM31 does vouch for the methodology and instrumentation. If I were reviewing a report or publication I would insist on seeing several calibrations against ice of known thickness. The difference between the two instrument measurements suggests that there may variations in conductivity within the ice such as cracks or inclusions of brine or seawater.

By: bill

bill — Fri, 01 May 2009 00:54:47 +0000

h.oldeboom (13:17:59) :
What is the scientific value of the Catlin expedition compared with the value of the very recent Alfred Wegener instite DC-3 fligt across the polar area? In a relatively short time the DC-3 did a huge amount of measurements

The radar measurements are very inaccurate:
http://www.awi.de/fileadmin/user_upload/Research/Research_Divisions/Climate_Sciences/Sea_Ice_Physics/pdf_poster/EM-Bird.pdf
Top right corner of PDF gives comparison

Errors often 25cm and up to 1metre in the short comparison given. Would you trust this data?

By: lettrist

lettrist — Fri, 01 May 2009 00:22:07 +0000

That’s interesting to see the 1979 – 2007 average. But it would be interesting to see the entire range of positions as a time series.

By: Earle Williams

Earle Williams — Thu, 30 Apr 2009 21:21:53 +0000

The Catlin expedition had the potential of being a very useful adjunct means to calibrate / verify the Wegener Institute airborne study. Any time you can ground tructh an airborne survey your greatly increase the confidence and value of the data collected from the air.

Imagine having a 300 km or greater transect of the ice thickness using ground penetrating radar. And this transect has been calibrated with numerous aurger measurements along the line. If you flew an airborne line along the exact same path as the surface transect you would have unimpeachable calibration data to supplement the interpretation of the EM results.

It seems that providing useful quantitative scientific data was not the primary mission of the Catlin expedition. That is truly unfortunate.

By: geo

geo — Thu, 30 Apr 2009 20:56:16 +0000

The scientific value of Catlin? Scientists got paid. You can’t have scientists without figuring out ways to get them paid. Grants got granted. Paper shufflers got to shuffle paper. Websites were hit and newspapers were sold. Heck, a grand old time was had by many!

Seriously, re that comparison it would be interesting to know the lead times on the two projects as to planning and approval. Probably the Catlin people had no idea of the other project.

By: Vincentvoll

Vincentvoll — Thu, 30 Apr 2009 20:34:45 +0000

Conclusion’ cadre displaying the vindication of that’s proven.

By: h.oldeboom

h.oldeboom — Thu, 30 Apr 2009 20:17:59 +0000

What is the scientific value of the Catlin expedition compared with the value of the very recent Alfred Wegener instite DC-3 fligt across the polar area? In a relatively short time the DC-3 did a huge amount of measurements compared with the restricted amount of measurements of Catlin and the surveyed distance/area of AW was much longer/bigger. The fact, the DC-3 measurements have been done in a very short time gives me the feeling, that these measurements gives at least a better idea of the general ice thichkness situation because Catlin needs to much time and in this long time too much natural changes can happen in the ice situation.

By: JAN

JAN — Thu, 30 Apr 2009 19:04:00 +0000

Sorry, vg

No pun intended!

By: vg

vg — Thu, 30 Apr 2009 18:49:44 +0000

S Goddard my silly… should check myself LOL

By: Juraj V.

Juraj V. — Thu, 30 Apr 2009 18:35:44 +0000

JAN, this is utterly unbelievable. Whatta scientific method! I saw a graph relating global temperatures to Iceland population and its regression was R=0,98 maybe.
Recently I read pretty cool sentence: “mainstream science is on the verge of being overturned by the efforts of a group of dedicated amateurs” (The Australian Financial Review, April 23) – so lets roll!

By: zonko

zonko — Thu, 30 Apr 2009 17:59:43 +0000

Very interesting!