tag:blogger.com,1999:blog-1367053740188758246.post949697033873675929..comments2023-06-21T00:39:34.443-07:00Comments on Dosbat: Arctic Dipole: A dominant role.Chris Reynoldshttp://www.blogger.com/profile/16843133350978717556noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-1367053740188758246.post-45198835137600448662012-06-25T11:04:10.340-07:002012-06-25T11:04:10.340-07:00Needless to say I agree that physics must back up ...Needless to say I agree that physics must back up the components resulting from EOF analysis. However soemtimes such mathematical analysis reveals patterns and new avenues of research.<br /><br />On this page:<br />http://dosbat.blogspot.co.uk/2011/08/arctic-dipole-sea-ice-loss.html<br />I discuss a paper in which both Zhang and Wu were involved - surely this implies that the authors don't see the difference you do. <br /><br />That research connects low sea-ice events with the positive mode of the AD, which is defined as the 2nd EOF - the dominant EOF component is the AO, but the period of analysis is 1948 to 2008, so wouldn't reveal the emergence to dominance of Zhang's Arctic Rapid Change pattern. That there is a measureable impact on Arctic sea ice extent strongly implies that the second component from the EOF analysis is not a mere abstraction.<br /><br />With regards the differences between Zhang and Wu, I can't add anything to my earlier reply, sorry.Chris Reynoldshttps://www.blogger.com/profile/16843133350978717556noreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-36237211048056961122012-06-24T20:52:42.828-07:002012-06-24T20:52:42.828-07:00EOF is a mathematic tool. Its results must be veri...EOF is a mathematic tool. Its results must be verified by physics. EOF modes can be artifacts without physics. This has been extensively discussed in literature. The composite analysis using Zhang et al.'s ARP clearly shows changes in the observed atmospheric circulation systems, such as Icelandic low, Siberian high, and Aleutian low. But I cannot see what physics Wu et al's EOF2 represents. Overland and Wang clearly shows a arbitrariness of EOF2 and 3, from your reply above. I believe Zhang et al. and Wu et al. discussed different things from physics point of view.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-63318455189601876912012-06-16T13:04:03.976-07:002012-06-16T13:04:03.976-07:00Hi Anonymous,
Not got time to re-read the papers ...Hi Anonymous,<br /><br />Not got time to re-read the papers right now. But from memory regarding your points...<br /><br />1) Different studies cover different extents, however the AD does have a wider hemispheric reach as shown by Wu et al<br />http://www.soest.hawaii.edu/MET/Faculty/bwang/bw/paper/193_WuZhang_Wang_Sea_ice.pdf<br />That is the same Bingyi Wu as the paper ref'd in the post.<br /><br />Here's what Overland & Wang have to say about the differences in patterns between those studies: "Our EOF3 has a resemblance to the second<br />EOF/dipole pattern of Wu et al. (2006) and Wang et al. (2009)<br />where the geostrophic winds are oriented on an Alaskan/Kara<br />Sea axis. Our EOF2 and the Wang et al. (2009) summer dipole<br />pattern are oriented more with Fram Strait. Because of the Buell<br />pattern relationships, a linear combination of the regional EOF2<br />and EOF3 can represent the dipole /meridional pattern with all<br />possible orientations."<br />Ref - "Large-scale atmospheric circulation changes are<br />associated with the recent loss of Arctic sea ice."<br /><br />2) As the first figure in the above post shows, the ARP has emerged out of a shift in center of action. So Zhang and Wu's patterns are necessarily different as they cover different periods. Wu finds a dipole pattern in an earlier period to the changes Zhang finds in the emergence to dominance of what they call the ARP. However Overland and Wang (and other researchers seem to view the patterns as part of the same phenomena).<br /><br />3. This has been largely covered in the above two reply points. However if you look at Overland & Wang you'll see more difference from Zhang and Wu.<br /><br />I've been failing to see the AD when it was there because I was too doggedly looking for the patterns I'd seen in the literature I've read. All I look for now is a rough pressure dipole with centres generally in Siberia and Greenland/North Canada.<br /><br />As a result* I now think the AD is the explanation for a pattern I've noted in another post.<br />http://dosbat.blogspot.co.uk/2011/09/summer-daze.html<br />* also partly because NSIDC have noted the role of the AD in all summers since 2007.Chris Reynoldshttps://www.blogger.com/profile/16843133350978717556noreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-27931354448948951332012-06-16T01:09:31.301-07:002012-06-16T01:09:31.301-07:00I ran into this page and found this interesting po...I ran into this page and found this interesting posting. Following the discussions here, I read the two papers by Zhang et al. and Wu et al. I believe there is a misunderstanding or misinterpretation of Zhang et al.'s and Wu et al.'s findings. Zhang et al.'s "Arctic Rapid change Pattern (ARP)" is completely different from Wu et al.'s AD:<br /><br />1. ARP is a hemispheric phenomenon, but AD is not.<br />2. ARP is the leading mode that explains >20% of total variance but AD is the second mode that only explains 13% of total variance.<br />3. ARP and AD have completely different physics as indicated by the composite analysis of sea level pressure. ARP has one variability center in the North Pacific and Beaufort Sea and the other in Eurasia (Figure S1 in Auxiliary Materials, Zhang et al. (2008)), while AD has one center in the Laptev Sea and the other in the Icelandic Sea (Figure 5, Wu et al. (2006)).Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-37277117077634098452011-08-12T11:49:23.205-07:002011-08-12T11:49:23.205-07:00Chris,
Yes, the chart is dynamic. I've expand...Chris,<br /><br />Yes, the chart is dynamic. I've expanded the steps, now 16M to 5M and of course, with 6M scaled for 2011, the road to the 5M bar has started building. The splice point is July 2002, but maybe for a few days shift, nothing big. Sorry for that not being clear, so I'll add a note to the legend when revisiting.<br /><br />The plan is still to make one also with GSFC data that go back to 1972, mostly for my own satisfaction. Also one against Area and that can be done with a single dataset. Those take time, me own.<br /><br />--SekeRobAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-71879544163740682272011-08-12T11:05:28.672-07:002011-08-12T11:05:28.672-07:00Thanks Peter,
Seke Rob,
Thanks for the info, I no...Thanks Peter,<br /><br />Seke Rob,<br />Thanks for the info, I note that the graph has been changed (it no longer looks like the one I linked to). Yes I was aware of the note, it confirmed what I already knew, but I didn't know the datasets had changed in 2003.<br /><br />I'm too busy to give this matter the time it requires right now so I'll reply again over the weekend.Chris Reynoldshttps://www.blogger.com/profile/16843133350978717556noreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-1308535181207530972011-08-12T02:09:32.568-07:002011-08-12T02:09:32.568-07:00Peter/Chris, plz see the footnote in the chart [al...Peter/Chris, plz see the footnote in the chart [always been there]. During the overlay period of both products, the difference mean was ~3 +/-2 days between the NSIDC and JAXA products and from 2003 to 2007 AND the further into the melt year the difference slim to below ~2 days. You be the judge of the significance of that, but don't think the <i>picture</i> should be assessed in isolation to other data, winter extent for one.<br /><br />For seeing the NSIDC/JAXA date differentials, refer to the separate charts I've shared over at Neven's, for the 10M 9M 7M and 6M. For latter there being actually too few data-points, but enough to see that there's *no* significance left IMO. <a href="http://i137.photobucket.com/albums/q210/Sekerob/Climate/ArcticSIEDaysbelow6million.png" rel="nofollow">ArcticSIE1stDay6Million</a><br /><br />More interesting to me in that latter chart is the step change of SIA per CT data... look at the inter-annual before 1998 and then on. Other charts display the divergence of SIA and SIE, and the <a href="http://i137.photobucket.com/albums/q210/Sekerob/Climate/ArcticSIA-SIERatio2.png" rel="nofollow">Extent Quality Indicator</a> or Breakup Index as I consider it too, which done on different datasets based elsewhere is called CAPIE.<br /><br />Per AWI March sensor flight measurement, the Beaufort had just 140cm left on FYI, where 2010 showed 160cm and 2009 170cm. Think that counts significantly and even with less optimal weather will go, given the relative high salt content of that, wherever that FYI got transported this season.<br /><br />-- SekeRobAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-51343058452886454842011-08-11T16:01:56.121-07:002011-08-11T16:01:56.121-07:00I'd be careful about reading too much into the...I'd be careful about reading too much into the change in 2003 in Seke Rob's graph. If I understand right, he's using both NSIDC and JAXA data, and the switch between the two is in 2002/03.<br /><br />If I've misunderstood, then I apologise!Peterhttps://www.blogger.com/profile/12559721137290332762noreply@blogger.com