62 replies to this topic

[Harry]

GaWx, on 27 March 2012 - 11:39 AM, said:

Looking at the NWS' ONI (trimonthly 3.4 anomalies) website, I just noticed that the "current" version of the ONI definition has just been updated to use various 30 year periods vs. the prior 1971-2000 base period. Examples: ONI values during 1950-1955 will be based on the 1936-1965 base period, ONI values during 1956-1960 will be based on the 1941-1970 base period, and so on and so forth. What I hate about this is that this potentially introduces confusion as regards prior ONI based analyses of the various ENSO phases' correlations to things like US wx since this new table changes the ENSO phase of many seasons vs. what it was using 1971-2000. Examples: 1951-2 is a moderate Nino using the newest table vs. weak Nino when using 1971-2000. 1952-3, 1953-4, and 1958-9 are now all weak Nino's using new table vs. neutral using 1971-2000. There are many other changes. Since I've pretty much always used the 1971-2000 base ONI table, I could always choose to stick with 1971-2000 to remain consistent as long as it remains available. I'm leaning toward doing just that at least for now.

1971-2000 base ONI table: http://www.cpc.ncep....000_climo.shtml

Newest ONI table: http://www.cpc.ncep....ensoyears.shtml

Description of changes to base periods: http://www.cpc.ncep....NI_change.shtml

Yeah.. I don't much care for this update. We now have Nino/Nina events ( per TM ONI ) that were not there before because ala the numbers got bumped/changed and thus see 05-06 for one example. 51-52 on the old one was a very weak nino and is now a moderate Nino. Also now includes a multi year nino from 52-53 through 53-54.. And 58-59 is now listed as a Nino as well. 63-64 is now a border line strong Nino..

[skierinvermont]

They did it because the oceans in general have been warming and will continue to warm. If they had continued using 1971-2000 for everything, then eventually we would be having way more El Ninos than Ninas.

[Harry]

skierinvermont, on 28 March 2012 - 06:54 PM, said:

They did it because the oceans in general have been warming and will continue to warm. If they had continued using 1971-2000 for everything, then eventually we would be having way more El Ninos than Ninas.

It changes the picture a bit where seasonal forecasting is concerned.

And IF that is the case why did we not see more Ninas show up vs Ninos? You follow me? Basically now they are saying ( atleast in the case of enso ) is the waters were warmer in those regions back in the 50s/60s vs what they HAD been showing?

[WxMidwest]

The frequency of ENSO events , Nina or Nino is mostly dependent on the Phase of the PDO. If SST's rise globally overall doesn't mean there will be more or less of one event or the other, much more dependent on the PDO SST cycles, and IOD precursors..

[Amped]

SOI has has crashed down to -26 in the last couple days.

[gil888]

Quick update is that the forecast new WWB has decreased a lot since a few days ago-- yet it would still be a significant event. So the march toward El Nino continues-- but not with the aid of one of the strongest
WWBs since the March 97 event.

[Amped]

-6.1 last 30 days
-28 today
http://www.longpaddo...index/index.php
Enso numbers should be climbing.

[skierinvermont]

WxMidwest, on 31 March 2012 - 08:54 PM, said:

The frequency of ENSO events , Nina or Nino is mostly dependent on the Phase of the PDO. If SST's rise globally overall doesn't mean there will be more or less of one event or the other, much more dependent on the PDO SST cycles, and IOD precursors..

If global temperatures rise, which they have and will continue to do, then so will tropical pacific SSTs (ENSO).

[skierinvermont]

Harry, on 31 March 2012 - 08:14 PM, said:

It changes the picture a bit where seasonal forecasting is concerned.

And IF that is the case why did we not see more Ninas show up vs Ninos? You follow me? Basically now they are saying ( atleast in the case of enso ) is the waters were warmer in those regions back in the 50s/60s vs what they HAD been showing?

Because they were already using the 1970-2000 baseline. If they stayed with that baseline then in the future there would be too many Ninos. They had to do something and this was the best option. Now there will be no more need to posthumously revise ENSO events.

Considering the hypothesized effect of the PDO however, it may have been better to use 40 or 50 year bases rather than 30 years. Using 40 or 50 year bases wouldn't have allowed for too much AGW contamination of classifications, but would have been long enough so that there wasn't too much PDO contamination either by encompassing nearly a full PDO 'cycle' (though I am not convinced that the PDO is truly cyclical).

[WxMidwest]

skierinvermont, on 8 April 2012 - 10:32 PM, said:

If global temperatures rise, which they have and will continue to do, then so will tropical pacific SSTs (ENSO).

I don't know about that, ENSO is based upon the idea upwelling colder water from further depths, not just SST's by themselves, even during warmer periods Oscillations like this have still occurred. It's not like SST's will rise and Peristent Nino conditions will just stay put. Our climate system is dynamic.

[physicsguy21]

There doesn't appear to be anything statistically significant going on in the Nino 3.4 region? The raw data: http://www.cpc.noaa....s/sstoi.indices

[skierinvermont]

WxMidwest, on 8 April 2012 - 11:31 PM, said:

I don't know about that, ENSO is based upon the idea upwelling colder water from further depths, not just SST's by themselves, even during warmer periods Oscillations like this have still occurred. It's not like SST's will rise and Peristent Nino conditions will just stay put. Our climate system is dynamic.

The deep oceans have and will continue to warm as well (which is the primary reason for sea level rise), albeit at a slower rate than surface SSTs. Even if 3.4 region SSTs warm, it wouldn't necessarily lead to a persistent Nino-like state because the weather will primarily be determined by SST gradients. As long as 3.4 SSTs are cooler than the surrounding the weather will probably resemble more of a Nina like state. In short, warmer 3.4 SSTs do not necessarily = persistent Nino. Which is why NOAA is now going to use a sliding 30 year base period. This captures the dynamic variation you speak of. When 3.4 SSTs drop below the most recent 30 year base it will be classified as a Nina, when they rise above, it's a Nino.

They could also have changed the index to use global SSTs as a baseline rather than region 3.4 SSTs. That's how the PDO has always been calculated. If global SSTs rise 1C, so does the PDO baseline. That might not work as well for ENSO though since upwelling is so intense which may lead to a slower warming trend.

[physicsguy21]

skierinvermont, on 8 April 2012 - 11:53 PM, said:

The deep oceans have and will continue to warm as well (which is the primary reason for sea level rise), albeit at a slower rate than surface SSTs.

They could also have changed the index to use global SSTs as a baseline rather than region 3.4 SSTs. That's how the PDO has always been calculated. If global SSTs rise 1C, so does the PDO baseline. That might not work as well for ENSO though since upwelling is so intense which may lead to a slower warming trend.

LWR from the atmosphere can only penetrate the oceans to a depth equal to the width of a human hair, so of course upwelling temperature from the deep oceans will turn up colder. Why would NOAA use a global SST base to represent this phenomenon? Sounds somewhat silly if true?.

[WxMidwest]

Baring Massive Underwater Volcanic Activity, or a severe increase in the sun's insolation effect on deep depth sea temps ( not that the sun can penetrate that far anyway physics wise), I really don't think it was required to change the ONI according to 5 Year intervals with rolling 30 year trends, it ruins the discrete definition of ENSO events. The idea of this absolutist warming of all levels of the ocean over time, even if it's at a slow rate, doesn't hold a lot of credence. The reason is, we still don't know alot of the eddy processes under the deep ocean, much like the UA data for models, or areas of the ocean. Then again, we are going to see this 2 different ways.

[RaleighWx]

SOI is in its longest negative streak since early 2010.

[wxmx]

Region 1+2 (+1.9) is at it's weekly warmest since Jul 1998, while the mega 1997-1998 Niño was in the decline. A Niño is not set in stone in spite of this, because this is the most highly volatile ENSO region, and ENSO 3.4 is still at -0.3...plus the Western ENSO regions are under steady easterly anomalies right now...but it might be a sign of things to come if there's a WWB/KW that can make it to the Central Pacific.

[am19psu]

wxmx, on 16 April 2012 - 04:06 PM, said:

but it might be a sign of things to come if there's a WWB/KW that can make it to the Central Pacific.

Memorial Day weekend?

[wxmx]

am19psu, on 16 April 2012 - 04:07 PM, said:

Memorial Day weekend?

Quite specific...but using the 40 day MJO wave propagation, that would be a good date

[JBG]

skierinvermont, on 8 April 2012 - 10:37 PM, said:

Because they were already using the 1970-2000 baseline. If they stayed with that baseline then in the future there would be too many Ninos. They had to do something and this was the best option. Now there will be no more need to posthumously revise ENSO events.

Considering the hypothesized effect of the PDO however, it may have been better to use 40 or 50 year bases rather than 30 years. Using 40 or 50 year bases wouldn't have allowed for too much AGW contamination of classifications, but would have been long enough so that there wasn't too much PDO contamination either by encompassing nearly a full PDO 'cycle' (though I am not convinced that the PDO is truly cyclical).

I've always been in favor of increasing all base periods to 50-60 years. 30 year cycles have the risk of cycle contamination.

[GaWx]

The current weekly Nino 3.4 anomaly is colder than all seven prior seven Nino's at this time in April with regard to weekly SST anom.'s.

[Amped]

The warm pool is pretty deep, but it may start to surface eventually. CFS V2 is pretty warm with the 3.4 region this fall.

[U_Thant]

The ECM T-depth graphic...

http://www.ecmwf.int...al_time/xzmaps/

...hasn't been updated since 2/29. Has the link been changed?

[MN Transplant]

U_Thant, on 2 May 2012 - 05:07 PM, said:

The ECM T-depth graphic...

http://www.ecmwf.int...al_time/xzmaps/

...hasn't been updated since 2/29. Has the link been changed?

Not sure about that, but this link shows the subsurface nicely, and you can loop it for the time period of your choice.

http://www.ncdc.noaa...rs/sea-temp.php

[U_Thant]

MN Transplant, on 3 May 2012 - 08:18 AM, said:

Not sure about that, but this link shows the subsurface nicely, and you can loop it for the time period of your choice.

http://www.ncdc.noaa...rs/sea-temp.php

Thx.

[GaWx]

From best as I can tell from the Euro model, the return of solid negative SOI's (which tend to accompany developing El Nino's, especially stronger ones) doesn't appear to return until at least after 5/15. The last three days have been positive.

[wxmx]

Looks like the prospects of a well established Niño are diminishing, and I suspect that Neutral or a very weak warm episode is looking more likely. 90/30/1 day SOI are now all positive, with trade winds still blowing anomalously strong near the dateline. Looks like some dampening of the winds is occurring soon, but anomalies still more on the easterly side of things...with no signs of a well established WWB going thru. Models are now playing catch up, with the latest CFS v2 now below mod Niño strength in it's latest iteration.

Earlier period
 nino34Mon.gif   18.49K   1 downloads

Latest period
 nino34Mon (1).gif   18.67K   2 downloads

A good 0.5 trimming in SSTs

[Amped]

Nuetral is fine. Won't ruin hurricane season and there's a shot at a semidecent winter. SUbsurface warm pool still present, which should keep away the nina. Fingers crossed.

[cyclogent]

The CFS2 still too warm IMO. My winter forecast is based on an ONI peak of 0.4 ONI (in OND), and a monthly peak of 0.6 give or take 0.1 in November. As much as I want to go ahead and post the analogs and all the other teleconnecting goodies for the Mid-Atlantic and Southeast snowcast for winter 2012-13, someone reminded me it's May. Which means MCS season, which will serve as a test for my analogs. :-)
Maps on the MCS tracks later.