The ENSO thread seems to have disappeared off the bottom of the forum so I'll start another one.

It appears La Nina is continuing to strengthen, and is getting more organised and less messy looking:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

The index values and SSTs in the Nino regions are moving towards moderate-strong La Nina territory now, and the forecasts have the event strengthening further still. Looks like the strongest Nina since 1999/00. It'll be interesting to see how this affects world climate patterns over the next few months: expect stories of drought in Kenya, floods in Southern Africa etc.

 

Thanks for providing this information. It will be interesting to see whether La Nina strengthens further and how long into next year it lasts. Could it cause 2008 to be globally cooler than 2007?

 

John S2:

Thanks for providing this information. It will be interesting to see whether La Nina strengthens further and how long into next year it lasts. Could it cause 2008 to be globally cooler than 2007?

I suppose that'll depend on a few factors including whether we bounce back into El Nino later in the year. Plus it's only one of many factors that affect year-on-year temperature variability.

In a way it's a shame we've not had ENSO events exactly coinciding with a calendar year for a while, as you could then much more easily see the effect of ENSO on annual temps. Neither the 1997/8 event nor 2001/2 lasted all through a single year.

Tim S:

In a way it's a shame we've not had ENSO events exactly coinciding with a calendar year for a while, as you could then much more easily see the effect of ENSO on annual temps. Neither the 1997/8 event nor 2001/2

Shouldn't a rolling mean iron this out?

It does of course, but obviously if you are looking at a year by year column chart, for example, you don't see this. The rolling 12 month mean in the GISS dataset peaks at Sept 98 (+0.59C), Oct 02 (+0.59C), April 04 (+0.54C), Nov 05 (+0.62C) and Oct 07 (+0.61C). 2002 loses out most from the non-calendar year Nino, as the annual mean was +0.56C, +0.03C cooler than the Oct peak.

Interestingly during 07 the rolling 12-month mean seems to have been at +0.61C every month since May, and likewise the rolling mean was above +0.59C from Aug 05 to Mar 06.

This is probably one of the most revealing graphs I've done yet. Isn't it just amazing. It's a plot of the annual PDO Index from 1900 to 2007, data sourced from here: http://jisao.washington.edu/pdo/PDO.latest . I've also created an Excel of the data which is here: PDO Excel

Two things really jump out at me.

1) The 107 year R^2 is 0.0002 ! For a trend to more or less cancel out to 0 is an amazing statistic for a natural oscillation. It shows how robust the cancellation of +ve and -ve phases are over 100 years.

2) Well, I'll eat my hat if there isn't a 30-32 year Cycle in there.

I'll make one prediction:

1) I think it 'highly likely' that in 2008 we will see that negative peak drive well towards -2, and it should stay negative for some considerable time after that. I believe the latest CPC data is already predicting a drop to -2.5 next year?

BLUE - PDO Annual     WHITE - PDO Moving 5 Year Average

Did I read somewhere that the some of the CPC forecast data goes as high as -3?  That is amazing and although I don't see your cycle I wouldn't doubt it with such a robust cancellation you've highlighted,  (What is your hat BTW?) 

Extreme Alde:

Did I read somewhere that the some of the CPC forecast data goes as high as -3?  That is amazing and although I don't see your cycle I wouldn't doubt it with such a robust cancellation you've highlighted,  (What is your hat BTW?) 

My Hat is liquorice - obviously - just in case

I've added a 5 year moving average trend for you, which I think highlights the 30ish year phasing more clearly.

 I like this para from the site supplying the PDO data.

Causes for the PDO are not currently known. Likewise, the potential predictability for this climate oscillation are not known. Some climate simulation models produce PDO-like oscillations, although often for different reasons. The mechanisms giving rise to PDO will determine whether skillful decades-long PDO climate predictions are possible. For example, if PDO arises from air-sea interactions that require 10 year ocean adjustment times, then aspects of the phenomenon will (in theory) be predictable at lead times of up to 10 years. Even in the absence of a theoretical understanding, PDO climate information improves season-to-season and year-to-year climate forecasts for North America because of its strong tendency for multi-season and multi-year persistence. From a societal impacts perspective, recognition of PDO is important because it shows that "normal" climate conditions can vary over time periods comparable to the length of a human's lifetime .

Update from NOAA issued 24th December:

 http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

Headlines:

1) A Moderate Strength La Nina is present
    Nino 4 -1.1C
    Nino 3.4 -1.5C
    Nino 3 -1.4C
    Nino 1+2 -1.7C

2) La Nina will continue into Northern Hemisphere Spring 2008

3) SSTs 1.0C-2.0C below average

4) The ensemble Mean suggests La Nina will strengthen during the next 3-4 months.

5) The Ensemble Minimum projected for February is near -2.75. This is not before recorded in the records since 1950 (if it happens)

What does the minus 2.75 prediction actually represent?

John S2:

What does the minus 2.75 prediction actually represent?

Hi John. There is an overall description of this on page 20 of the report.

"ONI (Oceanic Nino Index) is based on SST departures from average in the Nino 3.4 region, and is a principal measure for monitoring, assessing, and predicting ENSO. Defined over a 3 month running mean."

On page 27 are the model projections in 3 month blocks. Above +0.5 is defined as El Nino and below -0.5 as La Nina. You'll notice that even the most conservative model doesn't have us going into El Nino territory until at least Jun/Jul/Aug of 2008, and that is an outlier on its own. All the other models have nothing but Neutral to continuing La Nina until the foreseeable future which is August/September/October 2008.

If you refer to my graph further above this thread, you might just speculate that if the -2.0 to -2.5 comes off, this could possibly just be the PDO flip - highly expected by some anyway. If so, you'd not expect many +ve incursions for about the next 30 years. But, I may be getting carried away here. But the history of the last 100 years of the Index would strongly point to this.

Although many will regard this as poor news for the latter half of our 07/08 Winter - on a Global 30 Year Climate scale, this event could be absolutely pivotal. (But don't quote me on that ).

Very interesting 6 months ahead.

 

Waterspout:

Although many will regard this as poor news for the latter half of our 07/08 Winter - on a Global 30 Year Climate scale, this event could be absolutely pivotal. (But don't quote me on that ).

Very interesting 6 months ahead.

It would be shocking to experiance a La Nina as strong as that. It would surely have a VERY dramatic effect of cooling down the Global Temperature? I could see 2008 being the coolest year so far this millennium, if that forecast verifies.

Gavin P:

Waterspout:

Although many will regard this as poor news for the latter half of our 07/08 Winter - on a Global 30 Year Climate scale, this event could be absolutely pivotal. (But don't quote me on that ).

Very interesting 6 months ahead.

It would be shocking to experiance a La Nina as strong as that. It would surely have a VERY dramatic effect of cooling down the Global Temperature? I could see 2008 being the coolest year so far this millennium, if that forecast verifies.

Tom P may find it interesting.

I note that one ensemble member takes the index down below -4.

WS,

 I agree that a strong La-Nina would indeed produce low global temperatures for  a few months just as the strong 1997 El-Nino produced enhanced warming for a few months. However, I think you are going to have to spell out the 30 year significance. Note that I haven't quoted you at your request  (I do hope you like liquorice )