ENSO & IOD

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ENSO & IOD

Post  Johnno on Wed Jun 24, 2009 2:40 pm

As it looks more and more likely we may be entering into another EL Nino Episode the IOD still remains up in the air some models have changed from a Negative IOD to a weak Positive IOD for the coming months in a space of 4 weeks but going by the ssts the last week things have improved again up there after looking jittery the week before with a cooling period, also the subsurface Eastern Indian ocean is showing the opposite to the Positive IOD thats now predicted anyway here is a sample of what one of the global models think


A few recent dynamic predictions also hint a possibility of a weak positive Indian Ocean Dipole occurring during the same period. However, the subsurface conditions in the tropical Indian Ocean do not attest to this, at least as of now. Further, the historical lead prediction skills for the IOD events are relatively low as compared to those for the El Nino and La Nina events. Nonetheless, given the potential impacts the events may have if they materialize, the evolving conditions in the tropical Pacific and Indian Oceans in the next few months merit careful attention.


http://www2.apcc21.net/climate/climate01_01.php


Still some hope that we may not see a Positive IOD this Winter


Cheers, John.


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Re: ENSO & IOD

Post  Power Storm on Wed Jun 24, 2009 3:02 pm

Yeah John, it's not a given that an El Nino will develop yet, a moderate to high chance maybe, but not a given. It will be wise to pay attention to climatic models and indicaters such as the oceans of the next month or so. Another thing is that I don't find that El Nino's effect Victoria as much as other places, and I stress that it is my opinion that NSW and QLD get affected more, though Victoria does get affected sometimes. And they often bring more thunderstorms too, IMO again! Smile


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Re: ENSO & IOD

Post  droughtbreaker on Thu Jun 25, 2009 6:19 pm

Well, yes they do affect VIC more so than La Nina IMO.

1983 and 1994 were the two big ones which caused extreme drought in those years, but also 1991-1995 event whilst there were some extremely wet spells through that period and overall it was decent rainfall wise for VIC, there were also some very dry spells down here also associated with the El Nino sequence which mainly affected QLD etc. 1993 is a case in point where a potentially dry year was averted by an exceptionally wet spring. 1991 also was exceptionally dry from Feb to May.

A negative IOD saved us apparently and allowed those very wet winter/spring periods to eventuate. If we do not get a negative IOD with this coming El Nino (almost a given to develop) we are in big trouble, and quite frankly it is not looking encouraging at all with that large and intense area of warm anomalies off the horn of Africa (Somalia, Ethiopia etc.) and only weak positive anomalies and much less extensive around the NW coast of AUS.

I am very concerned that as part of the climate change package here in SE Aus is a lack and even absence of -ve phases of the IOD. they just don't happen anymore and if they do it is only very brief, eg. a few months or so.

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Re: ENSO & IOD

Post  Johnno on Sat Jul 04, 2009 9:32 am

Well no sign of a +IOD yet after the models decided to swing to a possible +IOD last month for Winter and Spring. Were into the 1st week of July now and the ssts look very good around Indonesia especially off Sumatra and Java & Unlike the past 3 Winters of 06,07,08 we are seeing constant NW cloudbands coming down from there & Northern and Western Vic have already been seeing some results from it the past 6 weeks or so. Got a feeling the models may have this wrong perhaps they have overdone there caculations of a weak +IOD developing in response to the El Nino developing but not always (usually) we get a +IOD with an El Nino and something tells me this year won't be one of those years & have thought this for a while now. The last 3 years by Early July waters were colder than normal off Indonesia but Sub surface under that area also remains warmer than normal so makes me wonder. The Box trees in NW Vic had a profilic & long period of flowering last Spring and Summer which is an indication of rain for the Winter and next Spring and so far NW Vic has done quite well this season.. They didnt flower at all the year before. I'm going to stick with mother nature than the models at the moment Smile

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Re: ENSO & IOD

Post  Karl Lijnders on Sat Jul 04, 2009 12:22 pm

Interesting that the models are indicating a large area of precipitation, >250mm, near Sumatra coming into the next week. May spawn a cloudband replacing the one presently over WA.

Might see increased rainfall this month in inland VIC. Potential flood warnings for NE VIC this month if it comes off from next weekend.
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Re: ENSO & IOD

Post  Malleefarmer on Sat Jul 04, 2009 8:39 pm

Also some cooling starting to appear off the African coast atm. Not much but a few cool anoms starting to pop up. Looking best in years around Indon so hopefully it can stick around. NWcloudbands are pretty frequent ATM just a pitty we cannot get one to link up and give us a big one to really get flows happening

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Re: ENSO & IOD

Post  Malleefarmer on Sun Jul 05, 2009 4:47 pm

Well I know that daily anom charts don't tell the full story but if you look at the lastest one, you would be forgiven to think we are in -IOD territory. Not strong but more warm water on our side.

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Re: ENSO & IOD

Post  hillybilly on Mon Jul 06, 2009 5:46 pm

The current pattern of SSTs is rather unusual. Really warm across nearly all the tropical oceans. The central/eastern looks almost like a classic El Nino, but the water around Australia looks almost La Nina like - which may well explain recent rain and the abundance of moisture coming in off the Indian OCean.

I'ld expect the eastern Pacific to eventually win out (as this water is warmer, more extensive, and supported by very large anomalies in the sub-surface) and put us into more classical El Nino conditions. Question is does the current abnormal pattern last long enough to set us up for an OK year runoff/crop/bushfire wise. For what they are worth (still experimental) the Bureau's coupled forecasts show wetter than average conditions continuing in the southeast until the start of August then it turning dry for Aug-Sep-Oct (http://poama.bom.gov.au/experimental/poama15/sp_rain.htm). This would be kinda like 2006, though hopefully not as severe.

I keep expecting a BIG high to develop and stall over eastern Australia marking the start of the El Nino dry, but thankfully that hasn't happened yet.

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Re: ENSO & IOD

Post  droughtbreaker on Mon Jul 06, 2009 8:18 pm

Well, it is well known that the 1991-1995 sequence of El Ninos that caused devastating drought in QLD had much less of an impact here. In fact we had some extremely wet periods, second half of 1993 comes to mind as the most spectacular of these. In that period, 1994 had a very strong El nino impact down here and there were brief periods of a few months or so here or there between 1991-1995 that were exceptionally dry also but apart from that we had some really wet periods to balance it out. Apparently this was due to -IOD at times during the El Nino events.

Could this be happening again?

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Re: ENSO & IOD

Post  Johnno on Tue Jul 07, 2009 9:18 am

Perhaps Andrew but not sure. I've also noticed the cooling in the Western and Central Indian Ocean Anthony and as this has happend ssts anomalies in the NE Indian ocean around Indonesia and North of Australia have gotten warmer and expanded so perhaps the models should of stuck to their earlier predictions of a -IOD in March, April & May? Before backflipping in June? Cos from what I am seeing it looks like the earlier predictions may be on track but tim will tell.

Interesting you say DJ that the Eastern and Central Equatioral Pacific is a classic El Nino but other things don't represent it for one the all important SOI both the 30 & 90 day SOI are as Neutral as it can get both near the 0 mark.

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Re: ENSO & IOD

Post  Johnno on Wed Jul 08, 2009 1:05 pm

Taken from the BOM today....


Summary: Strong indicators of El Niño persist
Indicators suggest an El Niño event is developing across the Pacific Basin. Conditions have reached a point that, should they persist at such levels through the remainder of the southern winter and into spring, 2009 will be considered an El Niño year.

Leading climate models indicate that warming of the Pacific will continue for the next few seasons, with very little chance of the current development stalling or reversing.

Continuing El Niño signals include central Pacific Ocean surface temperatures around 1°C above average, and supporting sub-surface temperatures up to 4°C warmer than normal. Trade winds remain weaker than average, and there is an emerging signal of enhanced cloudiness near the date-line

Conversely, the Southern Oscillation Index (SOI) rose over the past week to near zero. However, this would appear to be a response to local weather conditions near Darwin and Tahiti, rather than a long-term climate signal, and hence the SOI is likely to fall again in the weeks ahead.

El Niño events are usually (but not always) associated with below normal rainfall in the second half of the year across large parts of southern and inland eastern Australia.

After many weeks of positive values, the most recent value of the Indian Ocean Dipole (IOD), as measured by the Dipole Mode Index (DMI), was slightly negative. In the past, positive IOD values have been associated with drier conditions through south east Australia in winter and spring

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Re: ENSO & IOD

Post  Karl Lijnders on Wed Jul 08, 2009 1:40 pm

Thats a bit more promising!!! Now we need the westerly winds to stand up and start thumping through some frontal boundaries and cold air!!! They can then cut off over VIC!!
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Re: ENSO & IOD

Post  Guest on Thu Jul 16, 2009 8:39 am

There has been further cooling in the western IOD and a slightly warming in the SE IOD during the past week with the DMI in negative figures. They might start to regret changing there forecast to a +IOD.

http://ioc3.unesco.org/oopc/state_of_the_ocean/all/
http://ioc3.unesco.org/oopc/state_of_the_ocean/sur/ind/dmi.php

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Re: ENSO & IOD

Post  Johnno on Fri Jul 17, 2009 11:05 am

Yes David and this backs up whats your saying.. Surpise suprise Dr.Yamagta and his team have made a bit of a turn around back to a possible Negative IOD occuring in its latest (July) model update as of yesterday. El Nino also seems to be all over the place some are saying now this isn't your traditional El Nino and most atmospheric conditions show anything but El Nino across the planet at the moment & wouldn't be suprised if it fizzled out in the next few months anyway here it is.. from Dr. Yamagata and his crew from Sintex...

From Sintex Dr.Yamagata and his crew from the lastest July update...


Toshio Yamagata [2009-07-17 07:33:11 +0900]: > Dear Luo-san:>> This is interesting. The El Nino pattern is very much different from the & gt; conventional one; almost all equatorial region shows positive SST > anomalies with a peak at the central Pacific. It looks like the El Nino > Modoki pattern (as in unusually hot 2004 with so many typoons attacked > Japan) although the central Pacific warming is not sandwiched by cold > anomalies as we showed in Ashok et al. (2007) > [http://www.agu.org/pubs/crossref/2007/2006JC003798.shtml] and Weng et > al. (2007) > [http://www.springerlink.com/content/a36w326j63468186/?p=11314ee17f6d47d5be6f868f18308c1b&pi=0]>> If so, we may expect very hot condition in this summer as in 2004. > However, the prediction is just opposite with weaker than normal North > Pacific High. This needs to be watched hereafter.>> Regaring the Indian Ocean, the model predicts basin-wide warming as well > with very slight indication of a IOD as I expected from my > forecast in contrast to the SINTEX-F's prediction (perhaps > biased by too strong Pacific signal) in June


Dear Jing-Jia, Sensei and all, We just had an interesting APEC Climate symposium in Singapore.

One of the things we discussed was the fate of the current El Nino signal. Several folks pointed out that while the oceanic signals were consistent with El Nino (in observations, SST peaks at the eastern Pacific), the atmospheric response is almost non-existent. I myself contributed to the discussionby cautioning that the El Nino like SST anomalies will disappear faster than we expect based on forecasts, becuase the SST anomalies are simply not sustainable under the current atmospheric conditions. It will bevery interesting to see how the El Nino will/will not evolve. My estimate is that the conditions will be back to normal in two months time.

The evolving negative IOD also needs close monitoring. saji



Interesting... We shall see I'm gonna sit on the fence about this one


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Re: ENSO & IOD

Post  Power Storm on Fri Jul 17, 2009 3:52 pm

I still don't think it will happen. I am on natures side at the moment. Besides, its a bit all over the place regarding meteorology terms and El Nino thresholds atm.

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Re: ENSO & IOD

Post  droughtbreaker on Sun Jul 19, 2009 8:56 pm

Current indications are not pointing towards a full blown El Nino. There are warm anomalies in the Coral sea atm and also off the NW of Aus. Very interesting to here we may be heading into a -ve IOD, could almost be another 1991-1993 scenario up ahead and also 1995. With the PDO phase in our favour there is a good chance the El Nino signature may peter out as John mentioned and in that case we could have some very wet years ahead. Can only hope atm but it would be great to see.

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Re: ENSO & IOD

Post  Anthony Violi on Wed Jul 22, 2009 4:26 pm

droughtbreaker wrote:Well, it is well known that the 1991-1995 sequence of El Ninos that caused devastating drought in QLD had much less of an impact here. In fact we had some extremely wet periods, second half of 1993 comes to mind as the most spectacular of these. In that period, 1994 had a very strong El nino impact down here and there were brief periods of a few months or so here or there between 1991-1995 that were exceptionally dry also but apart from that we had some really wet periods to balance it out. Apparently this was due to -IOD at times during the El Nino events.

Could this be happening again?

Andrew, i guess the best way to tell is to look at historical records as to the relationship between the two. Maybe someone who has more time than me can look into this. Recently we have +IOD and La Nina simultaneously. And furthermore, a weak El Nino and weak - IOD would indicate some correlation in the coming months. And another thing, how long has there been records for IOD?
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Re: ENSO & IOD

Post  Johnno on Fri Jul 24, 2009 9:21 am

Don't know about you guys and it might just be early days but looking at the pattern and the general feel over the coming weeks its starting to look El Ninoish to me with no moisture at all over the inland Australia or Eastern Australia by Late July/August you tend to know what is really going on in years like this. The Setup over the coming weeks is starting to look like a combination of the 1994 and 2002 El Ninos both these Winter and Springs highs tended to dominate the inland with the Westerly belt bringing some relief to far Southern coasts of Australia (more exposed than anything else and Western Tassie).

The 2006 effects of El Nino was different.. Instead of having a dominant Westerly flow around tassie most of that season we got alot of strong highs developing well south of the Bight moving NE into the Tasman sea so all in all even the westerly belt was preety much non existant so Exposed coastal areas and Western tassie also remained quite dry as well as coastal NSW as the Highs moved NE right over that area so all in all the Westerlies were cut off as were the Easterlies for the NSW coast.. Be interesting to compare in coming weeks and months but it does look to me to have a feel of the 1994 and 2002 El Ninos, at least this way Far Coastal areas may get some relief over the coming weeks and months if this pattern were to remain unlike 2006 but could remain mostly dry inland for the rest of the year.

It wouldn't suprise me if parts of NSW and Southern/SE Qld end up with a record dry in some areas for the last 6 months of the year there (July-December) mother nature works in funny ways and after the incredible wet up there the 1st 6 months this year and the past 2 years in general I kind of expect this to happen now if July is anything to go by after being so dry up there this month(rainless in some areas even for July standards thats very poor considering Brisbanes & other places up there averages are actually bit wetter than Melbourne for July) I expect this pattern to continue the coming months up there with the dry extending right into Victoria with the odd brief interuption of wet spells for Coastal areas of Victoria. Anyway thats my 2c worth and how I see things for the coming months feel free to shoot me down in flames Laughing

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Re: ENSO & IOD

Post  Karl Lijnders on Fri Jul 24, 2009 9:57 am

Could not agree with you more. EC screamed El Nino this morning in it's run to me.
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Re: ENSO & IOD

Post  hillybilly on Sat Jul 25, 2009 5:51 am

Agree totally Karl. The next week or two doesn't look good. Hopefully the far south will scrape some rain, but further north it is looking rainless (after a tiny bit of patchy rain on Sunday). Also have noticed that the models are shifting back to the "down grade everything" mode.

Worth keeping an eye on the two week and monthly rainfall forecasts at http://poama.bom.gov.au/experimental/poama15/sp_rain.htm (this model includes an ocean and so tracks the evolution of El Nino/IOD etc). POAMA predicted a "wet" July but conditions turning drier from August onwards (initially in NSW and spreading south). This suggest August is likely to be dry in the southeast Rolling Eyes

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Re: ENSO & IOD

Post  droughtbreaker on Sat Jul 25, 2009 8:23 am

We have patterns like this all the time these days, whether it is El Nino, La Nina or whatever it is, it is our new climate and I have been waiting for the next period of high domination for most of this month because we rarely go more than a month or two without one. July is still shaping up as below average for here and probably most places despite heaps of strong cold fronts and lows. Rolling Eyes

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Re: ENSO & IOD

Post  hillybilly on Thu Jul 30, 2009 6:53 am

Usually (not always 1983 is an example) The Summers of an El Nino (weakening) get moister and more humid Andrew.. Summer of 97/98 was that way with regular rainfall in Jan and Feb after December being so dry, Summer of 94/95 was that way too exactly like 97/98 with Dec being dry and hot, Summer of 2002/2003 was that way but Mainly Feb that year was moister & Summer of 06/07 we saw lack of Northerlies and humid ENE winds instead through Jan and Feb so perhaps not all doom and gloom but the next 5 months do worry me.

Johnno, just a few rambling observations. One characteristics of El Ninos is enhanced westerlies over the oceans south of Australia which in some years can actually sneak far enough north to deliver rain in coastal areas. This looks to be happening ATM, and was certainly a feature of 1994 (when we had lots of westerly gales and a few solid showery fronts). If this pattern continues we may take the edge off the likely "El Nino" - fingers crossed. However, this pattern usually weakens by Nov/Dec when one almost always seems to shift to a pattern of high temperatures and dry conditions - this was certainly the case in 1994, 1997, 2002 and 2006.

As for the break down, the key is timing. Summer is usually the transition season for the breakdown of El Nino. If the breakdown happens early (such as 1995, 2007) we escape some of the worst effects. If it happens late - 1982, 2002 then summers can be downright horrible for the southeast with fire seasons which drag right through into autumn the following year. I doubt we can predict the exact timing of the break down of the El Nino influence, but my dumb observation is about half of the El Ninos seem to loose their grips in the first half of summer and the rest somewhat later.

PS notice the SOI is diving south http://www.longpaddock.qld.gov.au/SeasonalClimateOutlook/SouthernOscillationIndex/30DaySOIValues/ and the cloud bands out of the Indian Ocean have gone (with the IOD moving into positive territory). It looks to me like the El Nino is now gaining influence over Australia.

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Re: ENSO & IOD

Post  Johnno on Thu Jul 30, 2009 11:00 am

Thanks for that David. I do remember 1994 and was quite showery right through August to October with some good cold outbreaks right through that period but yes most of the time by November El Nino has taken a grip on most of the nation and can last into the Summer but as you say some Summers it may lose its grip earlier other Summers well into the Summer.

Theres hasn't been any cloud or moisture from the Indian Ocean for a fornight now Ssts anomalies are also becoming more negative up there. Not looking good.

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Re: ENSO & IOD

Post  Karl Lijnders on Fri Jul 31, 2009 6:15 pm

Thankfully the el niño trend is developing at the time when the westerly belt is most active. This is keeping the south nice and wet at the moment. Looks like frontal weather to continue for the future outlook. Looks as if the PW within the westerly belt is enough to support reasonable rainfall.

Need this to continue to years end!!!!
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Re: ENSO & IOD

Post  droughtbreaker on Fri Jul 31, 2009 9:34 pm

Probably clutching at straws here but it is worth noting that in January 1983 at the height of that horrific El Nino there were only 3 days above 30C in Melbourne (all above 35C) and 12 days below 20C. The average max temp ended up 1.6C below the long term average. In December 1982 the average max temperature was 0.4C below the long term mean and 47.4mm of rain in the city, (we had 75.1mm here), all be it almost entirely out of a major rain event or storm outbreak? around the 8th to the 10th. A similar pattern of long runs of cool days broken by a very hot day or two prevailed.

Feb 1983 was a real 'up and down' affair with exceptionally intense heatwaves breaking up mild periods of weather at regular intervals. Unfortunately those intense heatwaves were accompanied by nasty gales ahead of approaching cold fronts which, along with the extreme dry over most of the previous year, fueled the Ash Wednesday fires.

Compare this to January and February this year when we actually had a bit of a La Nina going, the heat was incessant and record breaking with very few even remotely cool days in amongst it save for the odd day about the coast and bays when seabreezes were in effect. Rainfall was almost non existent through most of the state in Jan and Feb (even in 1983 at least we got something worthwhile i.e. 21.1mm here in Jan), we had quite a few days with gale force wind, basically it ended up many times worse than the 1983 El Nino summer.

Again, probably clutching at straws, but in no way does El Nino have to automatically mean things are going to be worse than ever this summer. I don't see how anything could be worse than last summer. Given we are probably unlikely to have an El Nino anywhere near the magnitude of 1982/1983 which was massive, there is still a bit of 'hope' there.

Basically IMO, El Nino, La Nina or neutral it doesn't matter anymore, the main issue is climate change in general and the fact that any year can bring with it horrific weather in summer here in the SE.

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