Winter 2014-2015 Thread

[mitchnick]

How do you make Mitch excited, mad, happy, and sad all at the same time? Just post the last 25 CFS ensemble runs for December temps. The CFS is the sawed off shotgun of long range modeling. One pellet is bound to accidentally hit the target. 

 

cfsdec.JPG

hate to ruin the recent posts here with cfs2 talk, but Gawd, that is ugly for this winter

I mean 01/02 type ugly

[CAPE]

hate to ruin the recent posts here with cfs2 talk, but Gawd, that is ugly for this winter

I mean 01/02 type ugly

Good thing that model is pretty much worthless. Even so, out of those 25 runs for December, 15 are at least decent.

[CAPE]

Found this and bookmarked it a few months back, when I was trying to get a better understanding of ENSO and PDO interaction. Not sure how conventional the logic is here, but  for the most part it made sense to me, so either I am happily misinformed or hopefully a bit more enlightened. Anyway I figured I would throw it in the mix.

 

http://wattsupwiththat.com/2014/04/21/the-201415-el-nino-part-5-the-relationship-between-the-pdo-and-enso/

[GaWx]

Found this and bookmarked it a few months back, when I was trying to get a better understanding of ENSO and PDO interaction. Not sure how conventional the logic is here, but for the most part it made sense to me, so either I am happily misinformed or hopefully a bit more enlightened. Anyway I figured I would throw it in the mix.

http://wattsupwiththat.com/2014/04/21/the-201415-el-nino-part-5-the-relationship-between-the-pdo-and-enso/

I just read this linked article from Bob Tisdale. I got from it these things:

1) This one was a surprise vs what I keep hearing. I thought I read that Bob is saying

that N Hem temperatures are NEGATIVELY correlated with the PDO as opposed to the more often stated positive correlation because N Hem temps are positively correlated with the west-central part of the North Pacific (i.e., centered on dateline) as opposed to the eastern North Pacific. Did I read that correctly?? If so and if true, many people including JB may have the PDO's effect on global temperatures bass-ackwards unless there somehow is a positive correlation of S Hem temperatures with the PDO! I hope others check this out and let me know if I read this correctly.

 

*****Edit: I read this correctly. Here are the direct quotes and accompanying maps: "See Figure 20. The top map shows that surface temperatures of most of the Northern Hemisphere are negatively correlated with the PDO index. That negative correlation means that when the PDO data increases, the surface temperatures for most of the Northern Hemisphere show cooling. On the other hand, the surface temperatures for most of the Northern Hemisphere are positively correlated with the sea surface temperatures of the extratropical North Pacific. See the bottom map of Figure 20. That is, the surface temperatures for much of the Northern Hemisphere warm when the surface of the extratropical North Pacific warms, and it cools when the surface of the extratropical North Pacific cools."

 

 

Edit: This would appear to contradict what JB and other mets have been saying for years. It also may contradict what many people (from alarmists to deniers) have been assuming in our own climate change forum! Wtf?? 

 By the way, note that the top graph suggests a negative correlation of the PDO with E US temperatures. That is intuitive. Also, the Pacific correlations are intuitive. However, note also the widespread negative correlation to the PDO in the Arctic, Europe, northern Africa, and southern/far eastern Asia. Note the absence of positive correlations outside of the eastern north Pacific, Gulf of Alaska, southern Alaska, and ENSO regions!

2) Bob thinks that ENSO tends to drive PDO & not other way around. For example, I said as recently as today that there tend to be fewer strong Nino's, more weak Nino's, and more Nina's when there is a -PDO regime. My thinking was that the PDO regime is what causes these frequency changes although they tend to influence each other more or less. I think Bob would say I'm looking at it incorrectly since he says ENSO is the controller. Regardless, there still appears to be the correlations stated even if the PDO regime isn't the main driver.

3) Bob feels that climate models are off because they haven't even come close to simulating PDO related cyclical changes in the west-central/dateline portion of the North Pacific. So, Bob is saying that greenhouse gases are not responsible for warming and cooling of extratropical north Pacific SST's.

Any comments about these three items I mentioned from those who actually read Bob's article, especially the very surprising first item? Could JB, many other mets, and many hobbyists be totally wrong about the PDO's effects on global temperatures?? If the posted correlation maps are accurate, it would appear that may, indeed, be the case unless there is a very strong positive correlation to southern hem. temp.'s.

[millwx]

ENSO is also primarily wind-driven. Look what happened to the developing Niño with the lack of WWB activity this year...it fizzled out. The dynamics are no different as far as PDO SSTs are concerned...the Pacific Ocean doesn't just decide to flip it's PDO randomly...it needs to be forced to do so.

Let's make this easy. I have plotted SSTs and SLP data each month from January-May 2013. The strong N-PAC ridging seems to have forced the warm SSTs...not the other way around.

January:

February:

March:

April:

May

 

SofC,

 

This is compelling but unconvincing.  I fear we're not going to come to agreement on this.  Why?  Because once again, I don't actually disagree with you 90% of the way through this.  As I've noted a couple times up-thread, I'd completely concur with you that the PDO is pattern driven.  I've seen plenty of other studies that show that it's wind driven (and, to GaWx's point, also positively correlated to ENSO)... wind driven obviously equals pattern driven.  The problem is, that in no way precludes the SSTs from then having an influence on weather.  And, in fact, as I've noted numerous times (and this is why I think we'll just have to agree to disagree, because we're rehashing old arguments) this is supported both by the pattern correlations (lower relative heights over the SSTs, compared to the downstream ridging) AND the lag from PDO to U.S. weather (autumn PDO correlates well to winter U.S. weather).  This general idea ("general" because it was about Nino, not PDO... but since they are positively correlated themselves, it's definitely a relevant argument) is also supported by independent studies... like the one I mentioned up-thread conducted by the UKMO, which finds that (likely through Hadley cell manipulation) the autumn ENSO impacts the winter circulation (and, thus, the NAO).  I cannot find the original article in which I read that specifically, but a similar article (http://adsabs.harvard.edu/abs/2013EGUGA..15.7649M) does at least state, outright, that SSTs alter atmospheric flow. 

 

Bottom line... I'm following you and in total agreement with you almost the entire way through this process.  Where we disagree is on the final step... whether or not the PDO then feeds back into the atmosphere (at least in the specific way in which most mets use the PDO).  I believe the evidence is compelling.  The PDO (and ENSO) do feed back and alter atmospheric patterns.  Air-sea interaction is a complicated process and it's not a one way street.  Just because the PDO (and ENSO) are caused by atmospheric processes (on which we agree) does not make them incapable of, in turn, significantly feeding back on and impacting those atmospheric processes.  That's my argument. 

[wildweatherman179]

SofC,

This is compelling but unconvincing. I fear we're not going to come to agreement on this. Why? Because once again, I don't actually disagree with you 90% of the way through this. As I've noted a couple times up-thread, I'd completely concur with you that the PDO is pattern driven. I've seen plenty of other studies that show that it's wind driven (and, to GaWx's point, also positively correlated to ENSO)... wind driven obviously equals pattern driven. The problem is, that in no way precludes the SSTs from then having an influence on weather. And, in fact, as I've noted numerous times (and this is why I think we'll just have to agree to disagree, because we're rehashing old arguments) this is supported both by the pattern correlations (lower relative heights over the SSTs, compared to the downstream ridging) AND the lag from PDO to U.S. weather (autumn PDO correlates well to winter U.S. weather). This general idea ("general" because it was about Nino, not PDO... but since they are positively correlated themselves, it's definitely a relevant argument) is also supported by independent studies... like the one I mentioned up-thread conducted by the UKMO, which finds that (likely through Hadley cell manipulation) the autumn ENSO impacts the winter circulation (and, thus, the NAO). I cannot find the original article in which I read that specifically, but a similar article (http://adsabs.harvard.edu/abs/2013EGUGA..15.7649M) does at least state, outright, that SSTs alter atmospheric flow.

Bottom line... I'm following you and in total agreement with you almost the entire way through this process. Where we disagree is on the final step... whether or not the PDO then feeds back into the atmosphere (at least in the specific way in which most mets use the PDO). I believe the evidence is compelling. The PDO (and ENSO) do feed back and alter atmospheric patterns. Air-sea interaction is a complicated process and it's not a one way street. Just because the PDO (and ENSO) are caused by atmospheric processes (on which we agree) does not make them incapable of, in turn, significantly feeding back on and impacting those atmospheric processes. That's my argument.

I too believe that the evidence supports itself for feedbacks in atmospheric patterns. This was evident first by the extreme lack of Atlantic hurricanes in 2013 and also the record cold experienced in the central and eastern US during winter. This showed up early enough in the fall that I was able to very accurately forecast winter for my location. Also something that I find very compelling is that although there is a link between the PDO and Niño, the Niño failed last year. I still believe that it could very well fail this year as well. This is a very interesting discussion and I am glad to get to be a part of it or at least that it is happening. :-)

[GaWx]

 I'd like to reiterate what Bob Tisdale is saying about the NEGATIVE correlation of N Hem. surface temperatures to the PDO as per my post from last night in this thread. Go back up there to see the very telling accompanying correlation maps. This goes against everything I've heard for years about the PDO supposedly having a POSITIVE correlation with global temp.'s. I'm not taking Tisdale's side. I'm just trying to generate good discussions.
 Any opinions from anyone about this? Millwx or S of C, any opinion?

http://www.americanwx.com/bb/index.php/topic/42356-winter-2014-2015-thread/?p=3056343

 

 Quotes from Tisdale:

 

"CAN THE PDO DATA BE USED TO DETERMINE THE CONTRIBUTION OF THE NORTH PACIFIC SEA SURFACE TEMPERATURES TO GLOBAL WARMING?

It’s often noted that when the PDO is positive for multidecadal periods, global surface temperatures warm, and when the PDO is negative, global surface temperatures stop warming or cool a little. It’s is then assumed that the PDO has something to do with the warming or cooling of global surface temperatures. The problem: there is no mechanism through which the PDO can raise or lower global surface temperatures, because the PDO does not represent the surface temperatures of the extratropical North Pacific (where the PDO is derived).

(Note: Referring back to Figure 4, multidecadal variations in the strengths, frequencies and durations of El Niño and La Niña events are capable of raising and lowering global surface temperatures. Those processes exist. During multidecadal periods when El Niño events dominate, the tropical Pacific is releasing more heat than normal from the tropical Pacific to the atmosphere and redistributing more warm water than normal from the tropical Pacific to the adjoining ocean basins. The opposite holds true during multidecadal periods when La Niña events dominate. On the other hand, multidecadal variations in the spatial patterns in the North Pacific sea surface temperature anomalies, aka the PDO, are not capable of raising or lowering global sea surface temperatures.)"

[StudentOfClimatology]

SofC,

This is compelling but unconvincing. I fear we're not going to come to agreement on this. Why? Because once again, I don't actually disagree with you 90% of the way through this. As I've noted a couple times up-thread, I'd completely concur with you that the PDO is pattern driven. I've seen plenty of other studies that show that it's wind driven (and, to GaWx's point, also positively correlated to ENSO)... wind driven obviously equals pattern driven. The problem is, that in no way precludes the SSTs from then having an influence on weather. And, in fact, as I've noted numerous times (and this is why I think we'll just have to agree to disagree, because we're rehashing old arguments) this is supported both by the pattern correlations (lower relative heights over the SSTs, compared to the downstream ridging) AND the lag from PDO to U.S. weather (autumn PDO correlates well to winter U.S. weather). This general idea ("general" because it was about Nino, not PDO... but since they are positively correlated themselves, it's definitely a relevant argument) is also supported by independent studies... like the one I mentioned up-thread conducted by the UKMO, which finds that (likely through Hadley cell manipulation) the autumn ENSO impacts the winter circulation (and, thus, the NAO). I cannot find the original article in which I read that specifically, but a similar article (http://adsabs.harvard.edu/abs/2013EGUGA..15.7649M) does at least state, outright, that SSTs alter atmospheric flow.

Bottom line... I'm following you and in total agreement with you almost the entire way through this process. Where we disagree is on the final step... whether or not the PDO then feeds back into the atmosphere (at least in the specific way in which most mets use the PDO). I believe the evidence is compelling. The PDO (and ENSO) do feed back and alter atmospheric patterns. Air-sea interaction is a complicated process and it's not a one way street. Just because the PDO (and ENSO) are caused by atmospheric processes (on which we agree) does not make them incapable of, in turn, significantly feeding back on and impacting those atmospheric processes. That's my argument.

Yep, I think we've reached an impasse. We both seem to agree that the warm Pacific SSTs should create additional lift/reduce SLP in that vicinity, rather than raise pressures. However, we have not seen that response, and the strong ridging that preceded the N-PAC SST spike continued to strengthen over the 2013-14 winter, despite the warm SSTs. In fact, the SSTs responded, warming even further.

You seem to be arguing that the N-PAC SSTs changed on their own somehow? That makes no sense to me. The radiative budget over the ocean skin determines its thermals, as far as I know.

[millwx]

Yep, I think we've reached an impasse. We both seem to agree that the warm Pacific SSTs should create additional lift/reduce SLP in that vicinity, rather than raise pressures. However, we have not seen that response, and the strong ridging that preceded the N-PAC SST spike continued to strengthen over the 2013-14 winter, despite the warm SSTs. In fact, the SSTs responded, warming even further.

You seem to be arguing that the N-PAC SSTs changed on their own somehow? That makes no sense to me. The radiative budget over the ocean skin determines its thermals, as far as I know.

Nope, I made no such argument whatsoever.  In fact, I completely agreed with you on the cause (that said, 2013-14 is a horrific example to use, as the PDO correlation map itself indicates that 2013-14 is a major outlier... the ridge, under normal conditions, would NOT be perched directly over the SST max).  What you seem to be arguing, while also precisely stating otherwise, is that SSTs have no impact on atmospheric flow.  There is vast evidence to the contrary.  As such, to me it is completely beyond my comprehension that the PDO would have little to no influence on North American weather.

 

Anyway... we move on.  It was a great discussion.  We simply don't agree.

[wildweatherman179]

Yep, I think we've reached an impasse. We both seem to agree that the warm Pacific SSTs should create additional lift/reduce SLP in that vicinity, rather than raise pressures. However, we have not seen that response, and the strong ridging that preceded the N-PAC SST spike continued to strengthen over the 2013-14 winter, despite the warm SSTs. In fact, the SSTs responded, warming even further.

You seem to be arguing that the N-PAC SSTs changed on their own somehow? That makes no sense to me. The radiative budget over the ocean skin determines its thermals, as far as I know.

No, I believe the part that we are both arguing at this point is that once the warm or cold SSTS are in place they can become an additional source of influence to the pattern. It is believed that many of the coldest central, southern, and eastern US winters in the 1910s (1916-17 AND 1917-18) were driven throughout the winter by the anomalous heat in the NPAC just the same as 2013-14.

[millwx]

 I'd like to reiterate what Bob Tisdale is saying about the NEGATIVE correlation of N Hem. surface temperatures to the PDO as per my post from last night in this thread. Go back up there to see the very telling accompanying correlation maps. This goes against everything I've heard for years about the PDO supposedly having a POSITIVE correlation with global temp.'s. I'm not taking Tisdale's side. I'm just trying to generate good discussions.

 Any opinions from anyone about this? Millwx or S of C, any opinion?

http://www.americanwx.com/bb/index.php/topic/42356-winter-2014-2015-thread/?p=3056343

 

 Quotes from Tisdale:

 

"CAN THE PDO DATA BE USED TO DETERMINE THE CONTRIBUTION OF THE NORTH PACIFIC SEA SURFACE TEMPERATURES TO GLOBAL WARMING?

It’s often noted that when the PDO is positive for multidecadal periods, global surface temperatures warm, and when the PDO is negative, global surface temperatures stop warming or cool a little. It’s is then assumed that the PDO has something to do with the warming or cooling of global surface temperatures. The problem: there is no mechanism through which the PDO can raise or lower global surface temperatures, because the PDO does not represent the surface temperatures of the extratropical North Pacific (where the PDO is derived).

(Note: Referring back to Figure 4, multidecadal variations in the strengths, frequencies and durations of El Niño and La Niña events are capable of raising and lowering global surface temperatures. Those processes exist. During multidecadal periods when El Niño events dominate, the tropical Pacific is releasing more heat than normal from the tropical Pacific to the atmosphere and redistributing more warm water than normal from the tropical Pacific to the adjoining ocean basins. The opposite holds true during multidecadal periods when La Niña events dominate. On the other hand, multidecadal variations in the spatial patterns in the North Pacific sea surface temperature anomalies, aka the PDO, are not capable of raising or lowering global sea surface temperatures.)"

GaWx,

 

I apologize for not replying to this sooner, but I don't have a great deal of opinion on this, to be honest with you.  I'm always bothered by meteorologists lecturing on global warming.  While meteorology and climatology are similar in that they are atmospheric sciences, the specializations of the fields are completely different.  For example, in my daily forecasting I couldn't possibly care less if CO2 concentrations are rising... the concentration won't rise enough between now and next week to impact the weather.

 

And if I were to think about this, I'd be torn.  On the one hand, I actually WOULD expect the correlation to be negative.  When I think of the geographic coverage of the SST anomalies, it seems to me that a positive PDO actually has more cool than warm SSTs in the Pacific... only the NE (GOA) and extreme eastern Pacific are necessarily above normal.

 

...on the other hand, given the positive correlation, based on the standard wind flow, a positive PDO should be more often accompanied by warm ENSO events rather than cool.  Pushing the equatorial Pacific above normal would dramatically add to the geographical coverage of warm SSTs.  That would imply that, in fact, the correlation should be positive.

 

So, I honestly don't know and don't profess to be an expert on the matter.  As such, unfortunately, I don't think I can speak very intelligently on the subject.  I would say that given the broad concurrence opposing what Mr. Tisdale claims, I would at least be a little skeptical that perhaps he's misinterpreting something or not handling the data properly.  For example, is he de-trending the data?  He probably needs to.  He is only dealing with the 30yr climo period, according to his plot.  During that 30 years we have flipped from a positive to a negative PDO phase; meanwhile, there has been an observed rise in global temperatures.  As a result, there is going to be an inherent negative correlation (we were cooler, globally, during the positive PDO phase) which is (likely... again, I'm not an expert on global climate change) completely devoid of any causation.  What he may be showing is simply a prime example of the old adage in statistics, "correlation doesn't equal causation".  Again, I'm NOT saying he's wrong.  I don't know.  I'm merely raising this as a highly plausible scenario as to why his analysis may be incorrect.  He needs to de-trend the data and (or? ...I'd need to think about that) use a time period far longer than 30 years.

[StudentOfClimatology]

Nope, I made no such argument whatsoever. In fact, I completely agreed with you on the cause (that said, 2013-14 is a horrific example to use, as the PDO correlation map itself indicates that 2013-14 is a major outlier... the ridge, under normal conditions, would NOT be perched directly over the SST max). What you seem to be arguing, while also precisely stating otherwise, is that SSTs have no impact on atmospheric flow. There is vast evidence to the contrary. As such, to me it is completely beyond my comprehension that the PDO would have little to no influence on North American weather.

Anyway... we move on. It was a great discussion. We simply don't agree.

Oh, I agree that the SSTs influence the atmosphere above. That much is obvious (see ENSO and the effect those SSTs have on the bias of the MJO).

My position is that while the atmosphere leads the SSTs in general (the NPI leads the PDO by 2-4 months on average, AAM/WWB activity leads ENSO by about 4-6 weeks), the SSTs will have a counteractive effect on the pattern that forced them.

Example: ridging forces warm N-PAC SSTs, warm SSTs create additional lift, lowering surface pressures and weakening the ridge. See the cyclogenesis over the N-PAC over the next 2 weeks. While there are many reasons for that pattern (mostly typhoon forcing), the warm SSTs will enhance it as evaporation potential is very high right now as insolation decreases.

The coming pattern will likely cool the N-PAC, as a result.

[StudentOfClimatology]

No, I believe the part that we are both arguing at this point is that once the warm or cold SSTS are in place they can become an additional source of influence to the pattern. It is believed that many of the coldest central, southern, and eastern US winters in the 1910s (1916-17 AND 1917-18) were driven throughout the winter by the anomalous heat in the NPAC just the same as 2013-14.

Warmer SSTs would act to weaken ridging through increased lift/instability, reducing surface pressures. Basic thermodynamics here.

If the SSTs and atmosphere simply reinforced eachother, they'd never change. There'd be no ENSO, no PDO, no AO. The process of fluent oscillation requires disequilibrium.

[wildweatherman179]

Warmer SSTs would act to weaken ridging through increased lift/instability, reducing surface pressures. Basic thermodynamics here.

If the SSTs and atmosphere simply reinforced eachother, they'd never change. There'd be no ENSO, no PDO, no AO. The process of fluent oscillation requires disequilibrium.

It doesn't always work that way on land surfaces. I cannot expect it to always work that way over oceans. (Omega blocks can and have persisted over land for unusual amounts of time.)

There are oceanic currents at work that would never allow for equilibrium to take place. I'm not foolish enough to take things to that extreme. I appreciate the discussion but I also respectfully agree that we will not reach a conclusion here. Thank you for your thoughtfulness and presentation of a very great topic.

[Deck Pic]

Oh, I agree that the SSTs influence the atmosphere above. That much is obvious (see ENSO and the effect those SSTs have on the bias of the MJO).

My position is that while the atmosphere leads the SSTs in general (the NPI leads the PDO by 2-4 months on average, AAM/WWB activity leads ENSO by about 4-6 weeks), the SSTs will have a counteractive effect on the pattern that forced them.

Example: ridging forces warm N-PAC SSTs, warm SSTs create additional lift, lowering surface pressures and weakening the ridge. See the cyclogenesis over the N-PAC over the next 2 weeks. While there are many reasons for that pattern (mostly typhoon forcing), the warm SSTs will enhance it as evaporation potential is very high right now as insolation decreases.

The coming pattern will likely cool the N-PAC, as a result.

 

it's already happening, essentially in the core of the PDO region...40N at the dateline....as far as the greater point you have been trying to make, not sure I agree...have to side with the others on this one.....not saying your science doesn't make sense...but when we have had persistent -PDO periods (2011 and 2012 for example),  there was no sort of evening out as you suggest above...there was a persistent warm pool south of the aleutians, a ridge to the west of that and a trough to the east...As MIllwx has stated, the warm SST's (or cool if you are talking about a +PDO) correlate upstream and downstream, not overhead...

[StudentOfClimatology]

it's already happening, essentially in the core of the PDO region...40N at the dateline....as far as the greater point you have been trying to make, not sure I agree...have to side with the others on this one.....not saying your science doesn't make sense...but when we have had persistent -PDO periods (2011 and 2012 for example), there was no sort of evening out as you suggest above...there was a persistent warm pool south of the aleutians, a ridge to the west of that and a trough to the east...As MIllwx has stated, the warm SST's (or cool if you are talking about a +PDO) correlate upstream and downstream, not overhead...

Yeah, I get what he was saying, so I used sea level pressure analysis to avoid the hypothetical scenario of parcel drift aloft. The surface pressures don't seem to correlate to the SSTs, either, which suggests to me that the tropical forcings are governing the mid-latitude circulations, and the PDO. This explains why the PDO lags both the NPI (atmospheric pressures over the Pacific), and ENSO.

NCAR/UCAR highlight this nicely:

https://climatedataguide.ucar.edu/climate-data/north-pacific-np-index-trenberth-and-hurrell-monthly-and-winter

The North Pacific (NP) Index is the area-weighted sea level pressure over the region 30°N-65°N, 160°E-140°W. The NP index is defined to measure interannual to decadal variations in the atmospheric circulation. The dominant atmosphere-ocean relation in the north Pacific is one where atmospheric changes lead changes in sea surface temperatures by one to two months. However, strong ties exist with events in the tropical Pacific, with changes in tropical Pacific SSTs leading SSTs in the north Pacific by three months.

Frankly I've always thought this was pretty straightforward. The observations don't fit the data at all without an external governor.

It explains why the PDO signature exists in the first place...the warm pool doesn't just choose to show up one day..there must be a forcing or disequilibrium to prompt that sort of response...

[Deck Pic]

Yeah, I get what he was saying, so I used sea level pressure analysis to avoid the hypothetical scenario of parcel drift aloft. The surface pressures don't seem to correlate to the SSTs, either, which suggests to me that the tropical forcings are governing the mid-latitude circulations, and the PDO. This explains why the PDO lags both the NPI (atmospheric pressures over the Pacific), and ENSO.

NCAR/UCAR highlight this nicely:

https://climatedataguide.ucar.edu/climate-data/north-pacific-np-index-trenberth-and-hurrell-monthly-and-winter

Frankly I've always thought this was pretty straightforward. The observations don't fit the data at all without an external governor.

It explains why the PDO signature exists in the first place...the warm pool doesn't just choose to show up one day..there must be a forcing or disequilibrium to prompt that sort of response...

 

I don't think anyone disputes the relationship between ENSO and PDO......though it is far from perfect

[Isotherm]

This is one of the more interesting debates I've seen on the board, possibly in years, in that it's quite thought-provoking in terms of deciphering initial causation for the pattern (somewhat reminds me of the theological argument from efficient causality concerning the existence of God, e.g, tracing a line of causes).

 

1. It's pretty indisputable - if one examines the SSTA profiles of the north pacific before / during the ensuing winter, alongside the 500mb patterns of those same periods - that the ridges tend to develop immediately downstream of +SSTA, and the troughs tend to develop immediately downstream of -SSTA.

 

2. The question is -- does the SSTA "cause" the aforementioned scenario. It might be analogous to standing on the caboose portion of a train and saying, "It looks like the passenger car is pulling us"...when in reality, it's the locomotive (front portion) that's pulling the passenger car, pulling the caboose. In other words, the +SSTA (-SSTA) might coincide with and thus correlate to patterns in which there's dominant ridging (troughing) downstream of that geographical area. But the fact that those two variables are simultaneously occurring does not prove that the one causes the other.

 

3. I think it's best to understand the system as Earth's atmospheric patterns primarily setting the process in motion and leading SST anomalies, while SSTA anomalies can feedback and enhance the atmospheric pattern for a time...that is, until the atmospheric driver changes and begins to force a new SSTA structure. Therefore, I do believe the SSTA is of less importance, and the real key is detecting the plausible atmospheric drivers which will ultimately form the SSTA throughout time. I think what we've seen over this past year in the NPAC is anomalous mid level ridging in response to Rossby wave activity in 2013 that set the process in motion, developed the warm pool south of Alaska, and the warm pool was mostly a product of the atmospheric regime.

 

When a certain atmospheric pattern is in place and "semi-stable" for a time, I think feedback occurs with mid latitude SSTA on the downstream pattern, again, until a new atmospheric pattern / driver forces the development of a different SSTA orientation.

 

So in forecasting, one may examine autumn SSTA patterns in the NPAC, see warmth to the south of Alaska, forecast ridging in the Western NA continent, and be correct in said forecast. However, one must hope that the atmospheric driver is persistent and does not abruptly change in the middle of the cold season, resulting in a bust. But in most cases, certain 500mb patterns tend to lock in place for a sustained periods of time, such that it seems to give the impression that the SSTA could be the initial causation of the pattern. I would say not, except that SSTA can feedback and enhance the downstream pattern given atmospheric drivers that support it (and once the atmosphere no longer supports it, changes will ensue).

[Deck Pic]

looking good

 

[Deck Pic]

Mitchnick is going to like this too, and based on what I am seeing, next update will be even warmer...I don't know if this is just periodic oscillations or the actual final push toward Nino....

 

http://www.ospo.noaa.gov/data/sst/anomaly/2014/anomnight.9.15.2014.gif

 

keep in mind that the ONI is based on reconstructed SST's, and run colder than the OISST data set (see link above)...also models are measured versus OISST....not sure why the differential lately...but the idea that JJA was a 0.0 anomaly is BS...it was more like a 0.3...I understand this doesn't matter for comparison purposes...but in terms of anomalies we are pretty warm right now and should be warmer next update...I'd guess 3.4 is running +0.8 right now..

[Bob Chill]

This is one of the more interesting debates I've seen on the board, possibly in years, in that it's quite thought-provoking in terms of deciphering initial causation for the pattern (somewhat reminds me of the theological argument from efficient causality concerning the existence of God, e.g, tracing a line of causes).

1. It's pretty indisputable - if one examines the SSTA profiles of the north pacific before / during the ensuing winter, alongside the 500mb patterns of those same periods - that the ridges tend to develop immediately downstream of +SSTA, and the troughs tend to develop immediately downstream of -SSTA.

2. The question is -- does the SSTA "cause" the aforementioned scenario. It might be analogous to standing on the caboose portion of a train and saying, "It looks like the passenger car is pulling us"...when in reality, it's the locomotive (front portion) that's pulling the passenger car, pulling the caboose. In other words, the +SSTA (-SSTA) might coincide with and thus correlate to patterns in which there's dominant ridging (troughing) downstream of that geographical area. But the fact that those two variables are simultaneously occurring does not prove that the one causes the other.

3. I think it's best to understand the system as Earth's atmospheric patterns primarily setting the process in motion and leading SST anomalies, while SSTA anomalies can feedback and enhance the atmospheric pattern for a time...that is, until the atmospheric driver changes and begins to force a new SSTA structure. Therefore, I do believe the SSTA is of less importance, and the real key is detecting the plausible atmospheric drivers which will ultimately form the SSTA throughout time. I think what we've seen over this past year in the NPAC is anomalous mid level ridging in response to Rossby wave activity in 2013 that set the process in motion, developed the warm pool south of Alaska, and the warm pool was mostly a product of the atmospheric regime.

When a certain atmospheric pattern is in place and "semi-stable" for a time, I think feedback occurs with mid latitude SSTA on the downstream pattern, again, until a new atmospheric pattern / driver forces the development of a different SSTA orientation.

So in forecasting, one may examine autumn SSTA patterns in the NPAC, see warmth to the south of Alaska, forecast ridging in the Western NA continent, and be correct in said forecast. However, one must hope that the atmospheric driver is persistent and does not abruptly change in the middle of the cold season, resulting in a bust. But in most cases, certain 500mb patterns tend to lock in place for a sustained periods of time, such that it seems to give the impression that the SSTA could be the initial causation of the pattern. I would say not, except that SSTA can feedback and enhance the downstream pattern given atmospheric drivers that support it (and once the atmosphere no longer supports it, changes will ensue).

Point 3 is what most of us here completely agree on. The SSTA configs are clues and tools for setting expectations for downstream patterns. The only reason why any of us care about the state of the Pac is because weather patterns AND SSTA configs can have great effects on the weather on the EC. The Atlantic plays a role as well but a hostile Pac produces crap more often than not and a favorable Pac produces good more often than not (with exceptions of course).

We are all IMBY here. Nobody can convince me that a large pool of cold water in the GOA and warm water south of the Aleutians is a good thing for us. SoC's argument that the warm pool in the GOA has an inverse effect and breaks down the favorable pressure patterns. This logic would imply that a cold pool does the same. And while these arguments could be valid, the time frame that it takes to break things down doesn't do us any favors. I agree with you that there is quite possibly a feedback from SSTA's that delays a LW pattern change vs speeds it up. I think we've seen plenty of lasting good and bad patterns. Even is SSTA's have no effect on feedback into existing patterns, the fact that the existing pattern is stable and driving the favorable SSTA's is good enough for me.

I personally don't care much about delving into cause/effect much at all because I already know what I'm looking for from my armchair. I learned much of what to look for the in the Pac from Matt. The short story is an aleutian low / epac ridge during a +PDO config is money and the opposite is a winter cancel button (unless we get lucky and the ao/nao offset the flood of pac air). Another short story is favorable Pac sstas is a clear indication that a favorable and stable pattern is in place until it's time to go.

With our winter in the MA basically only spans 12 weeks or so, "waiting for the pattern flip" really sucks. We've been down that road many many times.

I like what I see in the Pac right now and I definitely like the direction it appears to be going in. The most recent update to SSTA's is only the beginning from how it looks right now on the ensembles. It's to early for me to set any winter expectations though. PDO/EPO are pretty volatile in the sense that we are 10 weeks from snow climo. If we have a classic look in late Nov/early Dec in that region then we can all say with some confidence that it will last for a while during our small window. If it looks like a disaster (becoming less likely it seems) then we all know the potential for trouble and we can start focusing on the HLs for help.

[millwx]

Mitchnick is going to like this too, and based on what I am seeing, next update will be even warmer...I don't know if this is just periodic oscillations or the actual final push toward Nino....

 

http://www.ospo.noaa.gov/data/sst/anomaly/2014/anomnight.9.15.2014.gif

 

keep in mind that the ONI is based on reconstructed SST's, and run colder than the OISST data set (see link above)...also models are measured versus OISST....not sure why the differential lately...but the idea that JJA was a 0.0 anomaly is BS...it was more like a 0.3...I understand this doesn't matter for comparison purposes...but in terms of anomalies we are pretty warm right now and should be warmer next update...I'd guess 3.4 is running +0.8 right now..

 

One reason for the differential is that the SST anomaly chart shown above does NOT (frustratingly, to me) use the standard 30yr climo as the base from which it calculates the anomaly.  Check out their methodology page (http://coralreefwatch.noaa.gov/satellite/methodology/methodology.php#ssta).  

 

...to quote...

 

"The monthly mean SST climatologies were then derived by averaging these satellite SSTs during the time period of 1985-1993. Observations from the years 1991 and 1992 were omitted due to the aerosol contamination from the eruption of Mt. Pinatubo."

 

That's a mere seven year climo.  Not the end of the world, since SSTs are more stable.  But given the decadal oscillations that we're all familiar with, this is certainly NOT an optimal duration on which to compute climo.

 

The ONI (and most other such indices) are calculated off of the standard 1981-2010 climatology base.  Not to mention there may be differences in both data input and analysis methodologies for the two differing databases.  So, the ONI (and all the Nino region SST anomaly values) are never going to perfectly match up with these SST maps.

[Deck Pic]

One reason for the differential is that the SST anomaly chart shown above does NOT (frustratingly, to me) use the standard 30yr climo as the base from which it calculates the anomaly.  Check out their methodology page (http://coralreefwatch.noaa.gov/satellite/methodology/methodology.php#ssta).  

 

...to quote...

 

"The monthly mean SST climatologies were then derived by averaging these satellite SSTs during the time period of 1985-1993. Observations from the years 1991 and 1992 were omitted due to the aerosol contamination from the eruption of Mt. Pinatubo."

 

That's a mere seven year climo.  Not the end of the world, since SSTs are more stable.  But given the decadal oscillations that we're all familiar with, this is certainly NOT an optimal duration on which to compute climo.

 

The ONI (and most other such indices) are calculated off of the standard 1981-2010 climatology base.  Not to mention there may be differences in both data input and analysis methodologies for the two differing databases.  So, the ONI (and all the Nino region SST anomaly values) are never going to perfectly match up with these SST maps.

 

uggh...didn't realize that...they are still useful to look at...Though I was talking about ERSST vs OISST...ONI is a 30 year data set, but is reconstructed data that recently runs colder than OISST....

 

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml - ERSST

 

http://www.cpc.ncep.noaa.gov/data/indices/wksst8110.for - OISST (also 30 years)

[Deck Pic]

My guess is we'll still see ENSO oscillations for the next month...by mid to late October we should see a more linear rise if we are in fact getting a Nino...

[nflwxman]

My guess is we'll still see ENSO oscillations for the next month...by mid to late October we should see a more linear rise if we are in fact getting a Nino...

I'd guess we are on a general push towards a nino at this point.  The EKW is very close to surfacing if the subsurface triton data is to be believed.

 

[GaWx]

I'd be very surprised if we don't get an ONI based Niño (five trimonths in a row of +0.5+ in 3.4) this fall/winter. Unlike the last few months, we now have not just some but ALL of these supporting factors: TAO buoys (significantly warmed to near +0.7 in 3.4 and westerly sfc wind anomalies in 3.4), Cowan's satellite based graph (now at +0.613 in 3.4, warmest since June), warm subsurface, six weeks of solid -SOI's, and several months of model consensus support for 3.4 rise to resume in Sep. I'm expecting a weak to possibly low end moderate El Niño to dominate fall/winter.

[Deck Pic]

what I am looking for now is whether we get a negative height anomaly in the NPAC in October and if so where it sets up (hopefully south of the Aleutians)...we have an aleutian low right now...

 

EDIT - look at the 8-10 day height anomaly on the Euro south of the aleutians..if we have that this winter with a weaker nino (not confident we will get that pattern if the nino is too weak), we are in great shape here in DC*

 

*as usual, I only care about DC metro...there is absolutely no way I could care less about how the pattern affects 40N...There is no such thing as "we" in the winter

 

[T. August]

what I am looking for now is whether we get a negative height anomaly in the NPAC in October and if so where it sets up (hopefully south of the Aleutians)...we have an aleutian low right now...

 

EDIT - look at the 8-10 day height anomaly on the Euro south of the aleutians..if we have that this winter with a weaker nino (not confident), we are in great shape here in DC*

 

*as usual, I only care about DC metro...there is absolutely no way I could care less about how the pattern affects 40N...There is no such thing as "we" in the winter

 

I'm pretty sure everyone feels that way lol. But when DC does well, the whole MA tends to do well.

[Deck Pic]

I'm pretty sure everyone feels that way lol. But when DC does well, the whole MA tends to do well.

 

yes, but the inverse isn't true...

[T. August]

yes, but the inverse isn't true...

I almost added "and vice versa", but unfortunately that isn't always the case.