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If you're wanting to learn more about weather, Lyn-M has a couple of weather books she'd like to give away to a good home. :) 

 

Bring Back1962-63

​​​​​​​LEARNING ABOUT TELECONNECTION SCIENCE AND BACKGROUND SIGNALS

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I realise that the thread is eager to move on from the basics of things like the MJO; however I would like the opportunity to complete the musings from my first post by looking at how the MJO moves and whether we can predict its movement?

Why does the MJO travel from west to east?   I have seen a number of theories over time but for me the most convincing is that of coupled planetary waves. This is not as frightening as is sounds.

 Here are a couple of images one showing a schematic diagram  cross section through the area of convection and the second an OLR anomaly chart from my first post.

studyofcloud.thumb.jpg.6fd4c6a3d7401f5b14b145febbd80914.jpgolr_anom_30dayjan.thumb.gif.e6b1620348e77bae44a1ac5c3cff1316.gif

 

The MJO cycle starts in the West Indian Ocean accompanied by a burst of westerly winds, as the air passes over the warm ocean it is heated and convection is created as shown by the cross section. As a consequence of this convection the air rises and the air near the surface it is replaced with air from nearby, thus the air is said to be converging at low levels. Higher up the air diverges and flows away from the convection it then converges with air coming from the opposite direction; this converging air sinks and diverges at the surface and completes the cycle. On the westerly side of the convection the sinking air causes the convection to be suppressed, this can be seen by the area of brown colour near the equator at about 70 degrees east (a ridge). On the eastern side of the convection we find the easterly trade winds,  they are close to the area of high OLR anomaly around the dateline, these are drawn into the convection and enhance it. So we have the convection being nibbled away on the western edge and added to at the eastern edge. It is this that gives the impression of movement west to east.  You could imagine it as a giant heat engine travelling around the equator against the prevailing wind. The waves referred to at 70 east and the other obvious waves further west are the planetary waves, in this case Rossby waves. These waves are important to the weather at our latitude.

You can read more here from the Met Office. http://onlinelibrary.wiley.com/wol1/doi/10.1002/qj.49712656902/abshttp://onlinelibrary.wiley.com/doi/10.1002/qj.49712656902/abstract

Can we predict the movement of the MJO?

I believe the MJO phase charts are created using these wind flows specifically at 200hp (high level outflow) and 850hpa (low level inflow), in conjunction with the OLR charts. Here is the one day OLR anomaly chart for Monday.

 

5a68bbd7484bc_onedayOLR.thumb.gif.13075372de4cdbcf49b60d8bf1713756.gif

 

As you can see on a daily timescale it has a lot of “noise” and looks chaotic, I suspect that integrating this with the MJO phase chart would present some challenges. The Global Circulation Models (GCM) and Numerical Weather Programmes (NWP) struggle to accurately predict the movement and strength of the MJO. If you use a search engine to look for MJO and GCM you will see some gnashing of teeth over this, you may also notice that it is an active area of research.

I came across this recently https://ams.confex.com/ams/97Annual/videogateway.cgi/id/37087?recordingid=37087&uniqueid=Paper302240&entry_password=987428 from the American Meteorologist Society it gives some insight as to why the speed of propagation is important. You might want to skip the first 4 or 5 minutes.

What we do know is that the MJO historically travels predictably at about 4 to 7 meters per second, say 9 MPH, which with a bit of arithmetic gives approximately 8000 /(24 * 9) or about 37 days to circle the earth, if it goes to form it becomes a useful for predicting in the medium to long term time range. We also know  what it is currently doing will have an effect on our weather in perhaps a week or two, making it a useful medium term prediction tool.

As mentioned earlier, it is the Rossby wave action that goes on to travel through the sub tropics and then on past our latitude that has a profound effect on our weather.

I’ve gone on longer than I intended, so I’ll stop. If I have made any howlers I apologise and am happy to be corrected.

Posting on public forums is not my natural habitat, so I would like to publicly thank Tamara for her supportive PM.

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:shok: But as AM says the Seasonal Cycle of the MJO and Its Association with the Extratropical Circulation doesn't take into account ENSO

 

Edited by knocker

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Hi Guys thought I'd post after lurking around and reading the posts must say I've learnt a lot reading through the thread so hat's off to @Bring Back1962-63 for creating this. 

So I'll ask some questions now to help my understanding of some of the teleconnections if someone could me with them. 

So my take is with the MJO progressing through Phases 6 and 7 that this should be beneficial in regards to HLB, however the low AAM means that we may not reap the benefits if I'm reading what has been said right? And the GWO is related back to the AAM with Phases 1/2/3 at low AAM and 4/5/6 with high AAM.  I presume we need a rise in AAM before we see more blocking? There is a few more questions I want to ask but I don't want to clutter up this thread too much. 

 

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Hello Summerstorm, welcome to this specialist thread. Good questions and keep them coming. I actually want to encourage these questions with answers given on the thread (not only by PM) so that many readers can also learn. It is the main point of the thread. I'm tied up for the next few days finishing off my business accounts and tax return but I hope some answers will appear before then. Thank you for your support. All the best, David

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I found the link to de daily data (https://www.esrl.noaa.gov/psd/data/composites/day/). This is the anomaly for the first three weeks of 2018.

1Gn9tZo.png

It looks as if this is not particularly typical of a La Nina pattern, especially because of the Rocky Mountains high. There should be a low over there. The high stretches out over the North Pole into Northern Russia. The high over Nova Zembla may be linked to the snow cover anomaiies in Russia, in accordance with the findings of Judah Cohen. December also showed this anomaly.

g9PsBfN.png

Anyway, there seem to be other forcings in play than the La Nina, this year. 

 

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On 24-1-2018 at 10:03, Paul123 said:

 

Sorry guys, double post. I don't know how to remove it. 

Edited by Paul123

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@nad, for your information here are the MJO verifications for NWP, predicting amplitude.

IMG_3761.thumb.PNG.3af483fce212aa2b239f7b6e87d31c12.PNG

As you can see, ECM and UKMO have pretty good forecasting skill for the MJO. The RMM sometimes doesn't represent the MJO signal very well, so VP200 can be better for that. Or Hovmollers. 

IMG_3760.thumb.PNG.192ee155a8729d4fda781a0ade4dd14c.PNG

I always like these plots, because there are so many forecasts to compare.

Most of the NWP models show decent amplitude into Phase 7.

was meant to post this just after I finished it, but took me 16 hours to hit post.

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12 hours ago, Summerstorm said:

Hi Guys thought I'd post after lurking around and reading the posts must say I've learnt a lot reading through the thread so hat's off to @Bring Back1962-63 for creating this. 

So I'll ask some questions now to help my understanding of some of the teleconnections if someone could me with them. 

So my take is with the MJO progressing through Phases 6 and 7 that this should be beneficial in regards to HLB, however the low AAM means that we may not reap the benefits if I'm reading what has been said right? And the GWO is related back to the AAM with Phases 1/2/3 at low AAM and 4/5/6 with high AAM.  I presume we need a rise in AAM before we see more blocking? There is a few more questions I want to ask but I don't want to clutter up this thread too much. 

 

That's all correct. The MJO is good for HLB, and we need a rise in AAM for more blocking. That is a very simple way of putting it though, there's probably a way more complex answer for that. Ask away, this thread needs more questions....

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Hi @Snowy Hibbo,

Thank you, I had not seen that website from the University of Tsukuba, http://gpvjma.ccs.hpcc.jp/TIGGE/tigge_MJO_score.html  it contains a wealth of information. You can scroll through the years between 2007 and 2013 and see that the verification statistics improve over the years, which I see as a vindication of the work put into this area. It was not my intention to imply that the GCMs and NWPs do not do a splendid job in their representation of the MJO; it was more to say that the developers feel that they could do even better. For example  snip >> The representation of the Madden–Julian oscillation (MJO) is still a challenge for numerical weather prediction and general circulation models (GCMs) because of the inadequate treatment of convection and the associated interactions across scales by the underlying cumulus parameterizations <<  https://journals.ametsoc.org/doi/abs/10.1175/JAS-D-14-0120.1 But yes, in my post  the words “struggle to accurately predict ...” does come over as saying that the models do a bad job. Thank you for pointing that out, after all I am here to learn.

 

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Predictability and Prediction Skill of the MJO in Two Operational Forecasting Systems

Quote

The authors examine the predictability and prediction skill of the Madden–Julian oscillation (MJO) of two ocean–atmosphere coupled forecast systems of ECMWF [Variable Resolution Ensemble Prediction System (VarEPS)] and NCEP [Climate Forecast System, version 2 (CFSv2)]. The VarEPS hindcasts possess five ensemble members for the period 1993–2009 and the CFSv2 hindcasts possess three ensemble members for the period 2000–09. Predictability and prediction skill are estimated by the bivariate correlation coefficient between the observed and predicted Wheeler–Hendon real-time multivariate MJO index (RMM). MJO predictability is beyond 32 days lead time in both hindcasts, while the prediction skill is about 27 days in VarEPS and 21 days in CFSv2 as measured by the bivariate correlation exceeding 0.5. Both predictability and prediction skill of MJO are enhanced by averaging ensembles. Results show clearly that forecasts initialized with (or targeting) strong MJOs possess greater prediction skill compared to those initialized with (or targeting) weak or nonexistent MJOs. The predictability is insensitive to the initial MJO phase (or forecast target phase), although the prediction skill varies with MJO phases.

A few common model issues are identified. In both hindcasts, the MJO propagation speed is slower and the MJO amplitude is weaker than observed. Also, both ensemble forecast systems are underdispersive, meaning that the growth rate of ensemble error is greater than the growth rate of the ensemble spread by lead time.

https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00480.1

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On ‎25‎/‎01‎/‎2018 at 00:17, Summerstorm said:

Hi Guys thought I'd post after lurking around and reading the posts must say I've learnt a lot reading through the thread so hat's off to @Bring Back1962-63 for creating this. 

So I'll ask some questions now to help my understanding of some of the teleconnections if someone could me with them. 

So my take is with the MJO progressing through Phases 6 and 7 that this should be beneficial in regards to HLB, however the low AAM means that we may not reap the benefits if I'm reading what has been said right? And the GWO is related back to the AAM with Phases 1/2/3 at low AAM and 4/5/6 with high AAM.  I presume we need a rise in AAM before we see more blocking? There is a few more questions I want to ask but I don't want to clutter up this thread too much. 

 

Hi there:)    The best way to think of the Global Wind Oscillation is a plot depicted calculation representative of the never ending exchange of wind-flows between the tropics and extra tropics. Changes of velocity of momentum of these wind-flows create frictional convergence or divergence - and these are represented as +ve frictional torques where convergence occurs, and -ve frictional torque where divergence of wind-flows occurs.

Based on the laws of conservation of angular momentum as @Bring Back1962-63 explains, coriolis angular momentum is affected according to whether there is greater easterly inertia in the global atmosphere  (-ve torque and lower angular momentum) and which acts to slow earth rotation, or whether there is greater westerly additions (+ve torque or higher angular momentum) to the planetary system which assists the coriolis effect.

Taking all these various momentum budgets into account, the GWO depicts the net balance of wind-flows at any given time through a plot depiction of atmospheric angular momentum according to whether there is greater easterly or westerly inertia in the atmosphere.

Easterly (or -ve momentum) acting to decelerate global wind-flow means that the jet stream deceleration initiation occurs at the point(s) of momentum loss (divergence)  This occurs across the Equatorial Pacific in response to the extra strength of easterly trade winds triggered by La Nina phasing.

The divergence zone(s) across the Pacific act to encourage amplification of the jet where the deceleration of the jet creates a downstream vacuum . This amplification is manifested by the spin up the sub tropical anticyclones as underpinned by the low level easterly trade wind flow. The propagation of these trades spreading across the latitudes of the tropics under mature La Nina low angular momentum conditions further encourages sub tropical ridge amplification circum-globally to mid latitudes. There is increased westerly polar jet energy to compensate for the easterly inertia added from within the tropics - and these westerlies flow atop the northern flank of these mid latitude ridges in the Northern Hemisphere.

The converse holds true for +ve momentum which creates a +ve frictional torque at points of wind-flow convergence. The best known macro cyclical and intra-seasonal phenomena of this type is the MJO - familiar to most readers of these domains.  Organised deep thunderstorm development tends to naturally occur over areas of greatest heat and instability and these both trigger and are in turn triggered by further convergence zones - the effect being to propagate more activity in response to outflow boundaries much in the same way as micro scale thunderstorm multi-cells propagate and increase into batches grouped together.

In this way, MJO progression patterns can be determined by ENSO phasing in terms of the spatial organisation of SST's across the tropical oceans. This is a dynamic and complex equation for anyone looking at long term or seasonal forecasting according to likely trends in these patterns. But the MJO, being a phenomenon that acts on reliably known repeat cyclical timelines,makes it possible to anticipate wind-flow changes that may occur at certain times as a result of forward moving tropical development and the resultant convergence zones they create - and which act to focus surface +ve frictional torque where they occur.

At some stage these areas of tropical convergence are going to meet stable divergent areas (-ve momentum). The impact zone is where the forward moving westerly wind bursts that are associated with macro scale MJO convection meet the easterly divergence zone. In a winter such as we have this year, we see that the lines of battle are drawn across the central and especially eastern most Pacific where the coldest SST's are places according to the La Nina profile.

This profile is rather further east than under many typical La Nina spatial arrangements of SST's and that means, in theory, that westerly wind propagation (+ve momentum) has greater chance of balancing the atmospheric angular momentum budget against the naturally higher weighted easterly trade winds that are the functional product of La Nina. Clearly there are many factors in play that are distortional to this and no one size fits all - not least, just as one example of variables, any solar geogmagnetic active state which plays a part in determining momentum of AAM through changes within the troposphere in the tropics and which can serve to boost the ferrel cell and augment further the process of sub tropical anticyclone strength that happens under traditional La Nina patterns.

The plot depiction of the GWO organises the net state of global wind-flow into phase depiction according to low AAM (and negative momentum torque processes between the tropics and extra tropics) and also high angular momentum (according to positive torque momentum processes within the tropics and extra tropics)

The spider graph these phases are overlain onto, are three distinct phases each for high AAM (Phases 5,6,7 or El Nino like) and low AAM (Phases 1,2,3 or La Nina like). There are also two 'transitional phases' which are indicative of momentum rising within or from a Nina state (Phase 4) and also one that is indicative of momentum in the atmosphere being lost within or from an El Nino type atmospheric state (Phase eight)

https://www.esrl.noaa.gov/psd/map/clim/test_maproom.html

Currently there is some uncertainty of speed of progression of added westerly momentum being added to the atmosphere c/o high amplitude MJO tropical convection heading on its way to the Western Pacific - so while GWO Phase 4 is currently indicated there is some question on the progressive indicated nature due to the lag times it takes for tropical >extra tropical propagation of additional westerly winds to start to influence the extra tropical mid and higher latitude tropospheric pattern

The latest GEFS GWO forecast is added in respect of the above, and it will be highly interesting to see how the model plot depictions of the GWO dovetail with the tropical>extra progression of momentum that NWP is currently seeing in terms of expected amplification in the 10 day + period. At the moment there isn't clarity on this and the plot forecast is maybe a little progressive.

gfsgwo_1.png

 

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While it is quiet here I would like to tie up a few loose ends on my understanding of the MJO and try to move the story on a little and into the subtropics. So what happened last week with the MJO? See the OLR anomalies:

olr_anom_7day.thumb.gif.a165db8468ccc8517f2bebfca5b4caa0.gif

We can see the area of long lived convection around the maritime continent and some new convection appearing in the central and Western pacific around 10 to 15 degrees north and south. These seem to be almost sneaking around the area of anomalously high OLR near the dateline and following the areas of highest sea temperatures. A digression: The Coriolis Effect is zero at the equator and gets stronger as you move north or south. The out flowing winds mentioned in an earlier post that flow away from the equator will at some point be affected by the Coriolis force and be deflected to the east. Wind that is flowing close to or along equator will be affected less. This has the effect of channelling some of the wind along the equator, sometimes called a “wave guide”, and the resulting wave is called a Kelvin wave.

So what happened to these high level winds that escaped from the equator? Here are the 250mb winds for the same period.

250wnd_07_rnl.thumb.gif.0efe49bfcb48a2c3ced380298d3a2895.gif

Concentrating on the Northern hemisphere, the areas of red and orange around 20-30 degrees north are where the strongest winds are, also called the subtropical jet. To me they look strongest to the north of the strongest convection. It is also interesting that the jet looks enhanced north of the area of convection in the Caribbean. Is the MJO adding a westerly wind component to the atmosphere?

A commentator on this thread suggested I take a look at the Forecast Model thread. At first glance it looks as if there is more to learn about human psychology than teleconnections; however, if you have your noise filter turned to maximum, there are indeed some nuggets of wisdom to be found, and I think you can guess which people are contributing them. One thing that I did see was that the MJO is/was forecast to move across the Pacific; maybe the charts posted support this. As ever I am always happy to be corrected.

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57 minutes ago, knocker said:

 

This is it. When ENSO is weak do other drivers take over as it were like the one mentioned above. Solar activity I suppose could play a big role in the vortex strength. Minimum or just after seems a opportune time for this as the winters of 08-13 showed

Edited by Matthew.

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AN APPEAL - CAN ANYONE HELP US IN ACCESSING SPECIALIST AAM DATA and GSDM PLOTS?

One of the very few sources providing access to key data that our specialists refer to in their posts on this thread was closed down yesterday without prior notice. This is the WDT website and their homepage provides a "Notice" and brief explanation on this link:   https://futures.wdtinc.com/   

The data that they produced included the following past, current and forecast charts for:

AAM - Atmospheric Angular Momentum tendency

FT - Frictional Torque

MT - Mountain Torque 

GWO - Global Wind Oscillation (alternative data is available for this - see below).

In the WDT "Notice" they refer to the NOAA site who had already withdrawn their support of the Global Synoptic Dynamic Model (GSDM) after their two scientists who had developed it both retired several years ago. This can be seen here:   https://www.esrl.noaa.gov/psd/map/clim/gsdm.composites.shtml

This is a double blow to anyone active in this exciting field of scientific research. Most of us are not professionals and cannot afford to pay substantial subscriptions to access the handful of remaining organisations that assemble and/or process this data. A small group of us might consider contributing a modest amount to share a subscription service. The advances in this area of teleconnection science have been significant in recent years. If we are to see more students and/or enthusiasts mastering this subject to take its development much further in the future, it's essential that at least the basic data is made available to every willing participant.

We are contacting a number of organisations and a few other known (worldwide) specialists in this field in the hope of finding a replacement source for the lost data. We feel that a few of you might be able to assist us in this quest. Do any of you have access to the charts described above? Alternatively, are you aware of anyone or any organisation that might be able to help? All suggestions would be appreciated - either by posting them on this thread or by sending me or any of us a PM ( @Bring Back1962-63, @Tamara, @Catacol or @Snowy Hibbo). Perhaps one of those professionals who has access is reading this? If so, could you get permission to post the relevant charts on here directly or provide one of us with the link. If this is restricted data, please state the terms of access, copyright rules and whether a free to view or a  subscription service.  Any leads or pointers would be appreciated.

Finally, we can still obtain information from the free to view Albany site with Nicholas Schiraldi and ERS (Earth Risk Science) data showing GFS analysis plots with past and current AAM (no forecasts and no torque charts) and the GEFS GWO plots (past and forecast) on this link:   http://www.atmos.albany.edu/student/nschiral/gwo.html

Thank you in advance for any help or suggestions. David

Edited by Bring Back1962-63
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And further to a tweet I've just posted in the short range thread

 

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Have been wondering recently what has been causing the "Ridiculously Resilient Ridge" (RRR), the ridge of high pressure in the Gulf of Alaska, that has been so dominant in the last 5 years or so. 

This article http://www.sfgate.com/weather/article/high-pressure-ridiculously-resilient-ridge-rain-12404417.php suggests this: 

"We've know for a long time that cool water temperatures in the eastern tropical Pacific Ocean associated with La Niña can produce a ridge in the Gulf of Alaska, which often tilts the odds in favor of winter high pressure near California and drier than average conditions especially in Southern California," Swain said. "But there's new, emerging evidence that the tropical west Pacific is just as important — and that unusual warmth there can produce a rain-blocking high pressure pattern right over California.

"This year, we have both conditions in play: cool eastern and warm western tropical Pacific. That would suggest an increased likelihood of winter ridging this year, and an increased chance of drier than average conditions especially across the southern half of the state."

There's also this: (from here: http://www.sciencemag.org/news/2017/12/vanishing-arctic-ice-could-drive-future-california-droughts)

In modeling runs with the low-ice condition, the Arctic’s global influence quickly became apparent. With less ice, the Arctic reflected less of the sun’s energy out into space, leading to a surplus of heat there. Within just 20 years, that had disrupted the usual flow of energy toward the Arctic from the tropics, leading to warmer-than-normal waters just north of the equator.

That excess tropical energy fueled rising air in a process known as convection, creating rain, releasing heat, and forming large-scale atmospheric patterns called Rossby waves. Those waves, in turn, led to the formation at midlatitudes of high-pressure systems, or “ridges.”

 

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Some interesting Gifs for your viewing pleasure :D

kcgBGuatVsIA8.thumb.gif.9cbffe340e74e7cf45b85b2913f629cf.gifQj0pLAk1wgHks.thumb.gif.9043396b043fdbec8ef49ed7ccaedd4a.gifOIDHkRgDmCL6.thumb.gif.1a417bbc43b2581b816697c07f72c161.gifBtq7TqGJ6g9O.thumb.gif.cd67c0daad770f8629a155b1241c5b26.gifQTJ72KLzzPsDC.thumb.gif.24cd61e2e4ddddd8b5d52360f23eac54.gifJWA4Tf2ksH0By.thumb.gif.51154da31904574c48c2a7d058bd423e.gifHFEqLEwBn0dkA.thumb.gif.bae7fec95f50d7118dad2736bf9c7aac.gifLGcXMkAedNgpG.thumb.gif.27d2118a233bb58df02ece35059281dd.gifH0VvGdnwbJux2.thumb.gif.26c9a7f77adad11ae6cbcccdc0663e11.gifl4Ep0lrlJjwzqZ4gU.thumb.gif.8198a012985a8b2809d20c78c55f3fdc.gifl0ExwqihAhRPFaVLq.thumb.gif.b4b7c0e7104dd697caf5c7258188c31c.gifGCBPvervHWnZu.thumb.gif.9e22ad1d81f5658e483f2e64b4580848.giftgQ00iRucdi7K.thumb.gif.dde7f7c16ede92ecf7cb412de0ef5fbd.gifK62UOoGFUCggM.thumb.gif.23fa334ec34e3e4468d495b73f9ca36a.gif

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Why don’t you post your thoughts in the model thread anymore  ,bring back,especially with a chance of an Easterly outbreak occuring

Edited by SLEETY

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Ever complicated teleconnections

 

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On 1/29/2018 at 16:56, knocker said:

Ever complicated teleconnections

 

Thanks for that knocker - interesting how that paper theorizes that Antarctic sea ice melt would cause the opposite effect i.e. a trough in NE Pacific. Ever complicated as you say, any effects of AGW seem to usually have another conflicting effect, from what I have read. 

I think it might be good one day to have a thread about the Aleutian Ridge - We could call it "We need to talk about the RRR". 

Edited by Bruegelian

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