Ruben Amsterdam
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Posts posted by Ruben Amsterdam
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Lars from our Dutch/Belgian forum "weerwoord.be" made some interesting GEFS output again. The ensemble below shows zonal winds according to the 00z GEFS. The operational run is obviously one of the members with high mean zonal winds. Next update will be similar graphs of the (much better) 06z run.
06 GEFS 10 hPa - 60°N mean zonal wind
06 GEFS 10 hPa temperature over the north pole (90°N)
Link to the forum thread (ancient set-up, scroll down for Lars' addition).
http://www.weerwoord.be/includes/forum_read.php?id=1938536&tid=1938536&exp=1-
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Yes, was just about to post it, that's a lovely run, cant help feeling if we could get to that situation then theres a chance of an SSW, however, we need to see it coming into a nearer timeframe and see it more consistently modelled.
Yep, we need consistency!
Looking good at 1hPa.
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Yes, I think somehow we are going to need wave 2 activity following quickly if we are to completely finish the vortex off.
06z shows what i mean: warm, warmer, warmest!
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Latest runs at 10hpa, 30hpa and 100hpa.
I do not think the warming in this 00z is going to cut it. We need higher temperatures on every next chart. Warming seems to be subsiding already at the end of this run.
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Because this possible warming is troposphere driven (right?), runs will vary significantly. Yes, the 06z run is almost completed now. In this run warming is delayed, but the cold vortex core remains stretched. The last charts show a warming again. (Positioning and shape similar to yesterdays 18z, but warming is less pronounced.) Far too much inconsistency from run to run to draw any conclusions yet.
Any news from the GEFS?
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The important thing to note, is the fact that even tho these correlations tells us a possible relationship between different parameters, they dont tell us what exactly is the relationship, or more importantly, who is the dominant one. For example, if I correlate the QBO and 30mb zonal wind, I know that the wind is the dominant over the index, since the index is calculated from that exact parameter.
Or for example NAO index and surface temperature, where NAO index is "dominant" since it is calculated from the pressure differences or the "pattern" which determines the surface temperature. The correlation with the sfc. temperature is weaker (tho still very high), since the surface temperature is much more sensitive to the pattern differences, while the area that "calculates" NAO has much more tolerance to these differences. This is the same way I made correlations last year, when I was searching for SSW precursor patterns simply by "cross-linking" different indexes/parameters.
So all in all, these correlations are a great tool, but some basic knowledge in meteorology is required, so you can correctly interpret the results.
Thank you so much for your great work, Recretos
Interesting to see a strong correlation between NAO and 30hpa gph. I wanted to do this myself, but did not know how Such nice graphics! Between you and me, ~0.6 is regarded as pretty decent in ecology (for field data). And you are completely right, an important thing regarding correlations is that they do not (always) provide insight in causalities. I'am pretty sure I can strongly correlate (with correlation coefficient of >0.7) the number of posts in this thread with the time till onset date of a major warming. This does not mean that increasing the amount of posts in this thread increases our chances of an SSW, of course. A correlation coefficient is more valuable if the causalities are known, i.e.: there is supporting theory.
By the way, those GEFS means, they look ok, don't they?
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Because we had a discussion last week on the relation between Sun Spot number/solar activity and the occurence of SSWs in the QBO west phase, I've been playing around with the data presented at the FU Berlin site. I am not a meteorologist or anything comparable (I'm an ecologist) and the analysis below is extremely simplified.
I filtered for years with a WQBO phase and plotted mean February 30hpa temperatures against January average sun spot number. General linear model revealed a significant correlation (p=0.0029 and R2= 0.29) between Jan. sun spot numbers and 30hpa temperatures in February. The correlation coefficient is not particularly strong, but overall the result was significant.
In the graph attached below, years with a Major Mid-Winter Warming in December are shown as circles, warmings in January are shown as squares and warmings in Febraury are shown in triangles. Years with no major warmings are shown in plus signs. I think the recent peak in solar activity and sun spot number (currently at 138 and flux at 175) is a good thing.
Because I am not aware of the causal mechanism behind the relation I found by playing around in R (don't you just love that?
), these results should ofc. be taken wit a grain of salt. Cheers,
Ruben
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It´s there again (at +348). Warming is also present in upper levels.
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The latest GFS runs were a variation on the same theme: a recovery of the vortex in combination with warming in the Asian sector.
Good too see EC with simalar warmings at the end of the run. Could this grow into a potent wave-1 attack?
Last chart of this 00z run.-
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The original Labitzke paper from 1987 uses January sun spot numbers.
http://onlinelibrary.wiley.com/doi/10.1029/GL014i005p00535/pdf
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I´m not too dissapointed by a R2 of 0.48. Certainly not when crude parameters like solar flux and QBO phase are used in a highly dynamical system. I actually think it's a quite decent correlation. I guess we can use it as a crude predictor. We have to be cautious as we do not know the underlying causal mechanism!
Meanwhile, GFS06z shows a slight improvement with regard to previous runs. It shows renewed pressure on the vortex at the end of the run. Wave-1 action?
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A USLM (Upper Strat/lower Meso) disturbance looks to be developing. From studies, this would indicate there is a 33% chance of major SSW within 14 days +/- 2 from this point.
To read more about USLMs, check out this study.
Are you sure the conditions are all met?
"This regionally conï¬ned temperature enhancement near 2 hPa in Figure 1 is part of an upper stratosphere and lower mesosphere disturbance that includes an unusually low-altitude stratopause near 42 km (2 hPa), a stratopause temperature in excess of 290 K (50 K above nominal conditions), a ~40 K cooling in the mesosphere near 75 km, and an undisturbed lower stratosphere [e.g.,Labitzke, 1972; von Zahn et al., 1998; Meriwether and Gerrard, 2004; Thayer and Livingston, 2008]. This thermal structure has been observed over the years and termed a “stratopause warming â€[ Duck et al., 2000; Braesicke and Langematz, 2000], "
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Sebastiaan, you recently asked (I can't find the exact post) what underlies the connection between EQBO/solar minimum vs. WQBO/solar maximum and the chances of Major Warmings under these conditions. With solar flux peaking over 200 today -and likely to stay high/increase over the coming days- I found this a very relevant question. Does anyone here know the exact mechanism? Sunspot number (#) is currently at 178. Similar years in terms of QBO and january sunspot number, ie. 57/58 (#203) and 78/79 (#167), featured major warmings in february.
Labitzke ends the 2005 summary paper with the following conclusion:
" The result of this paper is the introduction of the constructed annual mean of the solar cycle–QBO relationship. The differences of the solar signal in the two phases of the QBO are large and it is therefore necessary to stratify the data according to the phase of the QBO, in order to find the mechanism which transfers the direct solar signal from the upper stratosphere down to the lower stratosphere and to the troposphere. This new approach of an analysis of the solar signal may be useful for the interpretation of future model results."
Before doing any extensive digging in the literature, is anyone familiar with more recent papers adressing the same question?
Cheers,
Ruben
ps.: GFS12z indeed looks better. In the strat, at least.
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What are the chances of the Vortex revving back up again?
Well, it's a bit of a status quo. According to GFS, the vortex remains under wave-2 pressure at least the coming 240hrs. Chances are that it is allowed to breathe a bit more easily after this, and will ramp up temporarily in wind speed, gph, and temperature, like Chionomaniac said. I doubt it will ramp up to berserk-mode like we've seen last December.
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That GFS6h run was extreme. Perhaps some false expectations? Seemed to me (reading all interesting stuff over here) it would be a long term to knock the 'boxer' down (a muhammad ali stratosphere)
Let's hope for a knock-out in the third round
December 2013 achieved around 150 solar flux.
Since Christmas the solar flux rises again and yesterday around 180!
According to NOAA, solar flux will increase the coming days (185-190).
Penticton 10.7 cm FluxObserved 03 Jan 182Predicted 04 Jan-06 Jan 185/185/19090 Day Mean 03 Jan 146
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I agree. The double-sided (Asian and Atlantic) warmings we saw a while back are no longer as potent in recent runs. The attacks/warmings appear unable to penetrate the vortex (and get stranded in the surf-zone) and instead either subdue or circle around the vortex (conform the last two GFS runs; ofc. FI). Overall we can expect a reduction in mean zonal winds (except perhaps in the lower strat/trop at 70°NB, mentioned above), but I am less enthusiastic about our chances on a split/SSW within 14 days than I was at New Years Eve. Let's hope for January that the reduction in zonal wind is sufficient for some ML/HL blocking supported by the lower strat.I see, thanks.
I was away for a few days and what I notice now is that the warming at the 30hpa level has been downgraded especially over the North Atlantic/south Greenland area and the vortex continues to rule.
Because the warming doesn't seem to reduce the vortex strength significantly! If the warming was still looking as good as in the 6z GFS of 1st Jan then I would be much more positive. I mention that GFS stratospheric run because it was the last one I saw until last night. The downgrade is significant I'm afraid and if you look at today's 6z you will see that if anything the vortex is gaining strength by the end of the run.
Karyo
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After viewing the Berin strat charts of the ECM I have renewed confidence we will see
the stronger warming coming back on the GFS runs. Hopefully the 12z run this afternoon
will be a step in that direction.
After a rather underwhelming period around +144hrs, GFS12z is ramping up the warming from +216 onwards. Nothing is decided yet.
At +300 the 1mb-split is back.
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EC (02-01) features a (short-lived/not-quite-there-yet) split at 10hpa at +168hrs with the vortex being able to recover afterwards. GFS00z (03-01) shows a similar picture. After the "split" the vortex reforms again, only to split again at the end of the run.
EC looking pretty consistent at the end of runs. Only difference I can spot is the small warming near Greenland present in the most recent run (left).
Now, Recretos, I know 2009 featured a really intense warming and split type SSW. To what extend is the current situation comparable to the situation in 2009?
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So, Ruben what do you expect? In my opinion that significant and specteculair 10hPa warming in the 6h GFS was still beyond 192h and commonly seen as too progressive. Today's warming at the top (1hPa) by EC is the first step. Now we have to wait to see if it becomes reality and the process of downwelling. Patience is what we need.
Well, the US-warming (let's refer to it that way) is already more pronounced in GFS06 at 120hrs then in GFS00z (may be wishfull thinking, tho). I think yesterdays 06z was too progressive, but we may still some large differences between ops. But maybe it's better to leave it to the experts
The prolonged warming/pressure on the vortex at 1 hpa can only be a good thing, I guess. Edit: GFS06z downgraded the warming from +228 onwards. I do not like these downgrades/delays, Sebastiaan.
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I am pretty sure that he can do plots for any layer that is available after post-processing, which is 10-20-30-50-70-100 for GEFS stratosphere.
Maybe I don't understand your sentence, but anyway, the so-called GFS ensembles and GEFS are basically the same thing.
So the limitations that me and bluearmy were discussing earlier, apply to these plots. And even tho these products are really welcome because they provide an additional perspective, I am very dubious about the general usefulness of GEFS in stronger top-down events. But as I said many times now, the real test is yet to come. This is my first season that I am actually making custom plots, so I have no operational observations of GEFS stratosphere dynamics. And I am also monitoring CMC ensembles and the combination of both (NAEFS), and none of them delivers anything worth mentioning. Thanks Recretos, for your excellent post (please keep spamming
) I am aware that the GFS ENS is the same as the GEFS. That's why I mix them up. Perhaps better to be consistent with this terminology. Please excuse my English if it is not clear. By the way, I'm not that pleased with todays GFS0z. The small patch of warming over the American/Canadian sector does not amplify/intensify as we saw on the "good" runs (like yesterdays 06z). EC does not intensify this warming either. In the end, of course, these aren't bad charts, but I think we all prefer the agressive warming we saw on yesterdays 06z. It's good to see a significant reduction of zonal winds at 1hPa.
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Hi Aginob,
Lars told us he will make these GEFS plots more often. Maybe it's also possible for him to make 30hpa plots
I think they are usefull if we consider the limitations of the GFS ensembles (ie. model top and resolution). -
We seem to make one step forward (yesterday's 18z) and one step back (today's 0z).
Karyo
Reminds me of the song "One step forward, two steps back" by the Desert Rose Band. Luckily GFS06 makes a large step forward (one might even call it a leap at the end of the run).
Cheers,
Ruben
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GFS12z is not what I hoped for, unfortunetely. The vortex does get pushed towards the American Continent, though.
But for now: happy 2014!
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Erm, guys? Lookin' good!
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Interesting to see a strong correlation between NAO and 30hpa gph. I wanted to do this myself, but did not know how 
Such nice graphics! Between you and me, ~0.6 is regarded as pretty decent in ecology (for field data). 
), these results should ofc. be taken wit a grain of salt. 
The prolonged warming/pressure on the vortex at 1 hpa can only be a good thing, I guess. 
So the limitations that me and bluearmy were discussing earlier, apply to these plots. And even tho these products are really welcome because they provide an additional perspective, I am very dubious about the general usefulness of GEFS in stronger top-down events. But as I said many times now, the real test is yet to come. This is my first season that I am actually making custom plots, so I have no operational observations of GEFS stratosphere dynamics. And I am also monitoring CMC ensembles and the combination of both (NAEFS), and none of them delivers anything worth mentioning. 
Stratosphere Temperature Watch 2013/2014
in Spring Weather Discussion
Posted
Truly impressive upper strat warming at the end of the latest 18z!