usedtobe Posted October 18, 2011 Share Posted October 18, 2011 Ah, thanks, really appriciated. I'm wondering though, if fall snowcover is a driver of the -NAO for the following winter, why wouldn't winter snowcover matter if it is the same supposed mechanism acting on the block? I guess thats what confuses me, that winter snowcover wouldn't mean anything but fall snowcover somehow means something more substantial. Sometimes I wonder if it is the -NAO in the first place that is sparking an increase in NH snowcover, rather than the other way aroun. In the winter I know that is the case but in the fall it would make sense as well, unless I'm missing something in which case forget everything I just said I'm not sure on the impact of the negative AO and NAO would have on snow cover since they actually help jet the jet southward but warmer air over the polar region might lead to more moisture being available to produce snow. The problem though is usually a big mid level high pressure system inhibits upward motion and promotes Subsidence which would keep precipitation down under the high. As I undertand the physics (and I don't really) associated with the autum snow cover is that it tends to promote the lead to the development of a fall surface high where there is snow cover. The changes in the tropsophere actually feed back to the stratosphere and start weakening the polar vortex making it easier for any stratospheric warming event to create downwelling. Usually once you get a warming event in the stratosphere there is a delay between it and the development of a negative AO. This paper outlines how that might happen. If you want to discuss the October snow cover and how it might impact the AO and NOA, you should read it. http://www.nws.noaa.gov/ost/climate/STIP/FY11CTBSeminars/jcohen_062211.pdf Link to comment Share on other sites More sharing options...
BethesdaWX Posted October 18, 2011 Share Posted October 18, 2011 I'm not sure on the impact of the negative AO and NAO would have on snow cover since they actually help jet the jet southward but warmer air over the polar region might lead to more moisture being available to produce snow. The problem though is usually a big mid level high pressure system inhibits upward motion and promotes Subsidence which would keep precipitation down under the high. As I undertand the physics (and I don't really) associated with the autum snow cover is that it tends to promote the lead to the development of a fall surface high where there is snow cover. The changes in the tropsophere actually feed back to the stratosphere and start weakening the polar vortex making it easier for any stratospheric warming event to create downwelling. Usually once you get a warming event in the stratosphere there is a delay between it and the development of a negative AO. This paper outlines how that might happen. If you want to discuss the October snow cover and how it might impact the AO and NOA, you should read it. http://www.nws.noaa....ohen_062211.pdf Thanks a bunch, was definitely worh the read. I'm beginning to rethink my position on the matter, it'd just be nice if we could differentiate the different drivers & effects of the NAO, it'd make life so much easier for everyone. As for polar blocking, doesn't a -AO promote clear skies over the Arctic? During the witer when little to no sunlight makes it up there, it'd make sense to be thatthe surface would turn out cooler in a -AO while the LT would warm. Link to comment Share on other sites More sharing options...
ArtRosen Posted October 18, 2011 Share Posted October 18, 2011 HUGE gains in snow. On the 13th we had 3,470. On the 17th, we have 6,431, almost a doubling of the amount of snow in the northern hemisphere in 4 days. (net gain of 2,961) On the 13th we had 1,823 of ice and today we have 1,929 (net gain of 106). Looks like some kind of major shift just happened. Can anyone explain to me what's gone on in the past few days? That's a very large gain. Link to comment Share on other sites More sharing options...
QVectorman Posted October 18, 2011 Share Posted October 18, 2011 So all the maps that have been posted are counting NH snow cover but we are interested in specifically Euroasia/siberian snow cover so doesn't that contaminate our conclusion at the end of Oct.? Does Cohen offer the exact "area" used for his studies and does he have real time data available or does he only do post season analysis? Just read he says he uses the area of Siberia, just north of a series of exceptionally high mountain ranges, including the Himalayas, the Tien Shan and the Altai Link to comment Share on other sites More sharing options...
The_Global_Warmer Posted October 18, 2011 Share Posted October 18, 2011 HUGE gains in snow. On the 13th we had 3,470. On the 17th, we have 6,431, almost a doubling of the amount of snow in the northern hemisphere in 4 days. (net gain of 2,961) On the 13th we had 1,823 of ice and today we have 1,929 (net gain of 106). Looks like some kind of major shift just happened. Can anyone explain to me what's gone on in the past few days? That's a very large gain. Well, there has been a huge dipole anomaly going on in the arctic for a while now..I believe about 10 days with no end in sight yet. This is one large HP parked over the Canadian CA which cycles to the Beaufort area and another over Greenland. with nearly every open body of water up there above normal SST wise. Not just at the surface but going down some. There is likely extra moisture available with most of the SLPS traversing around the two HP's, one by the Hudson that has been stuck there that finally occluded and pinched off it's warm air supply and snow fell...don't expect that to stay around with warm air coming back and a train of slp's on the Russian side. Long term models are colder for Canada so snow pack should start to build in a week or two. But they are much colder for Russia now...so expect that to continue to build. Link to comment Share on other sites More sharing options...
BethesdaWX Posted October 18, 2011 Share Posted October 18, 2011 with nearly every open body of water up there above normal SST wise. Not just at the surface but going down some. There is likely extra moisture available with most of the SLPS traversing around the two HP's, one by the Hudson that has been stuck there that finally occluded and pinched off it's warm air supply and snow fell Above normal SSTA's in the Arctic I don't believe can be traced to rapid changes in snowcover over an entire hemisphere because they've been above normal for some time, and a dipole anomaly would promote gains in the eastern hemisphere regardless of SSTA state, so I feel the net effect cannot be deciphered. Changes over an entire hemisphere in a short timespan are a result of changes in the overall pattern, SSTA temps may factor in but I don't think you can accurately determine what, if any impacts they have other than on a local scale. Link to comment Share on other sites More sharing options...
Mallow Posted October 18, 2011 Share Posted October 18, 2011 http://www.natice.noaa.gov/ims/loop/nhem-1mo-loop.html Link to comment Share on other sites More sharing options...
WidreMann Posted October 19, 2011 Share Posted October 19, 2011 HUGE gains in snow. On the 13th we had 3,470. On the 17th, we have 6,431, almost a doubling of the amount of snow in the northern hemisphere in 4 days. (net gain of 2,961) On the 13th we had 1,823 of ice and today we have 1,929 (net gain of 106). Looks like some kind of major shift just happened. Can anyone explain to me what's gone on in the past few days? That's a very large gain. How do the pixels compare to last year? Link to comment Share on other sites More sharing options...
ArtRosen Posted October 19, 2011 Share Posted October 19, 2011 10/17/2010 Snow: 6,410 (2011 has more snow than 2010 had at this time +21) ice: 2,129 (2011 has less ice than 2010 had at this time -200) It should be noted that the summer of 2010 was not as hot as the summer of 2011. Link to comment Share on other sites More sharing options...
weathafella Posted October 19, 2011 Share Posted October 19, 2011 Snow cover on both sides of the pole is increasing at a nice clip now. The next 2 weeks are the most critical in the season IMHO. Link to comment Share on other sites More sharing options...
usedtobe Posted October 19, 2011 Share Posted October 19, 2011 Snow cover on both sides of the pole is increasing at a nice clip now. The next 2 weeks are the most critical in the season IMHO. I agree since the snow cover for the first half of October was below normal. Link to comment Share on other sites More sharing options...
ArtRosen Posted October 20, 2011 Share Posted October 20, 2011 October 19th, 2010 Snow: 6,779 (+369 from 10/17/10) Ice: 2,205 (+76 from 10/17/10) October 19th, 2011 Snow: 6,750 (+319 from two days ago) Ice: 1,953 (+24 from two days ago) 2011 vs. 2010 Snow: We have -29 snow in 2011 vs. 2010 Ice: We have -252 snow in 2011 vs. 2010 Comparatively, I checked out 2009. 2009 was also pretty high. 2009 had 2,178 in ice. So 2009 and 2010 were pretty similar as far as ice is concerned and were blockbuster winters for the mid-atlantic and northeast. Does that mean more ice = a better winter? Well, look at 2008. In 2008, we had a hell of a lot more ice than we had in 2009, 2010 and now. What can we tell? Snow is neck and neck. I'd say even. 20 or 30 pixels don't really matter that much with snow. Ice, however, is significantly less this year than it was last year. Just for reference, I went back to 2009 to see what 2009 had at this time and... Snow: 6,946 Ice: 2,178 There was more ice in 2009 and 2010 than we have right now. Interestingly enough, there was more ice in 2010 than in 2009 AND in 2008 than in 2010 - almost an 8% difference. So, this means that we have the lowest amount of arctic ice since 2007. But 2007 had 1620 compared to 1953 right now... apples and oranges. So, I went back to search for a similar year since 2004 where we had a near equal amount of ice and.... In 2006 we had 1934 pixels of ice, which is very similar to what we have today, but we had less snow back then than we do now (6,660). The closest year I can find, since 2007 when maps were first launched, is 2006. Interestingly enough, the late '90s (beginning with 1997) had a lot more ice than we had in 2008. (2500 vs. 2300). It gained year over year until 2001. And since 2001, we had less ice every year on this date until 2006. We lost a lot in 2007, had a great deal more in 2008 and have had less ice on this date every year since 2008. If there was some kind of logical pattern I could find out of this, I'd post it but the major ice loss in 2007 vs. the major ice gain in 2008 baffles me. Edit: Why did they start making these maps in 2007? Why not earlier? Link to comment Share on other sites More sharing options...
WidreMann Posted October 20, 2011 Share Posted October 20, 2011 You know, I'm having my doubts about the pixel count method. It shows us being about the same as last year, but the FSU data does not bear that out, with about 1 percentage point less coverage this year than last (which is about a 15% difference in relative terms). Then again, that's for the 17th. We've gained a bit in the last few days, but enough to make up for the difference? Link to comment Share on other sites More sharing options...
skierinvermont Posted October 20, 2011 Share Posted October 20, 2011 You know, I'm having my doubts about the pixel count method. It shows us being about the same as last year, but the FSU data does not bear that out, with about 1 percentage point less coverage this year than last (which is about a 15% difference in relative terms). Then again, that's for the 17th. We've gained a bit in the last few days, but enough to make up for the difference? Also the fact that with pixel method he is coming up with 2011 having more ice than 2006... totally incorrect. 2006 had over a million square kilometres more ice. Even using the IMS maps.. there's clearly more yellow ice area in 2006 than 2011 so I don't know why the pixel count doesn't reflect that. Also just eyeballing the snow coverage.. 2006 also clearly had way more but the pixel count is lower for some reason. The FSU data is clearly better, though a few days out of date. Link to comment Share on other sites More sharing options...
ORH_wxman Posted October 20, 2011 Share Posted October 20, 2011 Thank heaven 2006 is not the standard for winter. What a terrible winter that was for most of the east. Link to comment Share on other sites More sharing options...
QVectorman Posted October 20, 2011 Share Posted October 20, 2011 Again, I have to ask, why are we counting all the pixels for the NH when the research states it is the snow cover of only Siberia in October that matters?????? Link to comment Share on other sites More sharing options...
Sunny and Warm Posted October 20, 2011 Share Posted October 20, 2011 Again, I have to ask, why are we counting all the pixels for the NH when the research states it is the snow cover of only Siberia in October that matters?????? do you have a paper on that? I'd love to read about the research. thanks Link to comment Share on other sites More sharing options...
TheTrials Posted October 20, 2011 Share Posted October 20, 2011 Thank heaven 2006 is not the standard for winter. What a terrible winter that was for most of the east. Mega +AO will do that to you. Wasnt NYC close to 70 degrees around xmas? Link to comment Share on other sites More sharing options...
Mallow Posted October 20, 2011 Share Posted October 20, 2011 Moreover, I'm trying to figure out how this... Snow: 6,779 (+369 from 10/17/10) ... supposedly has so much less snow than this... Snow: 6,946 If anything, they look about equal to me, just eyeballing it. Is Art sure his pixel-counting methods don't have some bug/error? Link to comment Share on other sites More sharing options...
okie333 Posted October 20, 2011 Share Posted October 20, 2011 Moreover, I'm trying to figure out how this... ... supposedly has so much less snow than this... If anything, they look about equal to me, just eyeballing it. Is Art sure his pixel-counting methods don't have some bug/error? They are near-equal even on his count. Link to comment Share on other sites More sharing options...
usedtobe Posted October 20, 2011 Share Posted October 20, 2011 do you have a paper on that? I'd love to read about the research. thanks I've already posted it twice in this thread. http://www.nws.noaa.gov/ost/climate/STIP/FY11CTBSeminars/jcohen_062211.pdf Link to comment Share on other sites More sharing options...
BethesdaWX Posted October 20, 2011 Share Posted October 20, 2011 Also the fact that with pixel method he is coming up with 2011 having more ice than 2006... totally incorrect. 2006 had over a million square kilometres more ice. Even using the IMS maps.. there's clearly more yellow ice area in 2006 than 2011 so I don't know why the pixel count doesn't reflect that. Also just eyeballing the snow coverage.. 2006 also clearly had way more but the pixel count is lower for some reason. The FSU data is clearly better, though a few days out of date. What are you doing? The Ice pixels on the snowcover maps I believe are not represented in 30% coverage as seen on the DMI image you posted, so you can't expect 30% coverage to accurately represent what is being shown on the map before-hand. And if it does represent 30% extent then you're not getting the full picture on the 2006 vs 2007/09/10/11/etc shinanigans. And the reason you see differences in 2006 in the snowcover just might be to the curve of the planet and how "area" is represented, meaning what we see versus the amount of space actually covered. Below: If you're comparing 2007 to this year you'd use the 15% extent rather than the 30% knowing that 1) It would more accurately represent the image 2) Large amounts of multi-year ice were flushed from the Arctic during & after the 2007 summer, through the 2008 winter, so the 30% extent will naturally be lower at this time of year until that ice builds back later on. Link to comment Share on other sites More sharing options...
vortmax Posted October 20, 2011 Share Posted October 20, 2011 Again, I have to ask, why are we counting all the pixels for the NH when the research states it is the snow cover of only Siberia in October that matters?????? So the major increase of snow cover in Siberia as of late is very good news to snow lovers in the E US as it will help strengthen the Siberian high, hence starting the 'winter cycle' (according to the study)...sounds good to me... It would be interesting to see how the Siberian high responds to the snow cover this year. Anyone interesting in keeping tabs on it? Link to comment Share on other sites More sharing options...
BethesdaWX Posted October 20, 2011 Share Posted October 20, 2011 Moreover, I'm trying to figure out how this... ... supposedly has so much less snow than this... If anything, they look about equal to me, just eyeballing it. Is Art sure his pixel-counting methods don't have some bug/error? He didn't count them far apart anyway, the globe obviously has a curve to it so where the pixels are located may have some effect but I'm not sure on that. Link to comment Share on other sites More sharing options...
Mallow Posted October 20, 2011 Share Posted October 20, 2011 They are near-equal even on his count. 200 pixels isn't a huge difference, but it's a bigger difference than most of the other years he was looking at. And to me (though this could just be because I'm comparing them by eye), the 2010 map looks to have more snow than the 2009 map. Link to comment Share on other sites More sharing options...
SVT450R Posted October 20, 2011 Share Posted October 20, 2011 Here is comparison Oct 19 years 08-11. If it's to fast i can slow it down. Link to comment Share on other sites More sharing options...
WxUSAF Posted October 20, 2011 Share Posted October 20, 2011 From a Siberia perspective, it looks like this year is 2nd best or 1st best of those 4 years for snowcover. Pretty solid cover northward of 60N and eastward of 90E. Sea ice sucks though and snow on our side of the pole is fairly poor. Link to comment Share on other sites More sharing options...
QVectorman Posted October 20, 2011 Share Posted October 20, 2011 Since Siberian snow cover is what matters according to research why isn't anyone using these maps and use the magic wand tool to get a pixel count? I took a screen shot of my magic wand area used. If I am using the wrong area of Siberia someone please correct me. 2010 snow pixels: 13259 2011 snow pixels: 12042 Link to comment Share on other sites More sharing options...
skierinvermont Posted October 20, 2011 Share Posted October 20, 2011 What are you doing? The Ice pixels on the snowcover maps I believe are not represented in 30% coverage as seen on the DMI image you posted, so you can't expect 30% coverage to accurately represent what is being shown on the map before-hand. And if it does represent 30% extent then you're not getting the full picture on the 2006 vs 2007/09/10/11/etc shinanigans. And the reason you see differences in 2006 in the snowcover just might be to the curve of the planet and how "area" is represented, meaning what we see versus the amount of space actually covered. Below: If you're comparing 2007 to this year you'd use the 15% extent rather than the 30% knowing that 1) It would more accurately represent the image 2) Large amounts of multi-year ice were flushed from the Arctic during & after the 2007 summer, through the 2008 winter, so the 30% extent will naturally be lower at this time of year until that ice builds back later on. That graph is 2 weeks out of date. Jaxa stopped updating when AMSR-E was shutdown. 15% shows the same thing as the 30% graph I posted. Near dead last. Nowhere near 2006.. over 1 million sq km behind. The pixel counting obviously doesn't work. 2006 had way more snow and ice according to reliable sources... and yet the pixel counting gave 2011 more. Link to comment Share on other sites More sharing options...
ORH_wxman Posted October 20, 2011 Share Posted October 20, 2011 Since Siberian snow cover is what matters according to research why isn't anyone using these maps and use the magic wand tool to get a pixel count? I took a screen shot of my magic wand area used. If I am using the wrong area of Siberia someone please correct me. 2010 snow pixels: 13259 2011 snow pixels: 12042 E Siberia is doing very well but the Eurasian side is struggling...though we did make some gains there yesterday. Link to comment Share on other sites More sharing options...
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