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#1477881 - 30/11/2018 06:43 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 3505
Loc: Wollongong, NSW, Aus
I assume EP = eastpac, CP = centralpac et al?

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#1477882 - 30/11/2018 08:17 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2601
Loc: near Rockhampton, Qld
So what has happened to the predicted huge westerly wind burst?

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#1477892 - 30/11/2018 09:16 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
El Nino, Modoki and convection:

Petros is right to note that the location of warmest water in absolute terms is quite important. This is where the tropical convection tends to focus, and this drives the general tropical circulation. Normally the warmest water is near Australia, and the water becomes steadily cooler as you go further east. This means convection is focused near Australia, and as these waters are firmly warmer than the rest of the Pacific it tends to stay there.

In a Modoki pattern waters near the dateline warm up somewhat. If they get close to the temps near Australia then the convection is not dominated by the Australian region, but spread between Australia and the dateline region, so convection near Australia weakens. If the anomalies further east are roughly equal or cooler, then the temperature east of the drop line still drops off at a moderate rate, and the area near the dateline doesn't have to share convection with the waters further east (but does share with the region nearer Australia). Hence cloudiness increases near the dateline, but does not increase further east.

In a classic el nino the anomalies get stronger towards the east, so the temperature becomes much closer to level across a much larger portion of the Pacific, and convection is then spread out over a much larger area of the Pacific and cloudiness increases well out into the Central and maybe even the East Pacific.

This year the strongest warm anomalies have tended to be near 170E. So convection stretched out towards 170E, there have been persistent cloudiness anomalies in this region and a tendency towards westerly anomalies near and to the west of 170E. Cloudiness, westerly anomalies, and SST anomalies are clearly linked in this region. As the anomalies further east have been weaker these waters haven't been warm enough to take a share in the tropical convection and cloudiness hasn't spread further east into the region the BOM monitors.

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#1477905 - 30/11/2018 10:58 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: RC]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 3505
Loc: Wollongong, NSW, Aus
Originally Posted By: RC
So what has happened to the predicted huge westerly wind burst?


Best guess is it'll be diverted into the developing low, which will also form a monsoon trough you'd think given there is none atm (quite unusual I would have thought?)

As the low moves west (if as forecast) then you'd think the trades would increase to its east as a consequence.

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#1477950 - 30/11/2018 18:20 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Mike Hauber]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 8071
Loc: Maffra, Central Gippsland, Vi...
Originally Posted By: Mike Hauber
Most peer reviewed research defines Modoki as warmest SST anomalies near the dateline example

That has certainly been the case this year.

The original research referenced at the bottom of the Jamstec page refers to colder waters in the east, but also lists 1994, 2002 and 2004 as el nino modoki years.

This is what these Modoki el ninos actually look like:







Pretty clear that actual -ve temp anomalies in the east are not actually required for an el nino modoki. Considering the primary authors of these papers are presumably not English speakers (judging by names and published by the Japan agency) it is quite reasonable that by 'colder' they mean not as warm as near the dateline, and not colder than average, consistent with definitions in many other research papers.


Those charts relate to "compared to average", take the 1994 example, we are currently using anomalies from circa 1985-2005 dataset's. Apples with apples.

Darwin SST is 31C when I last looked yesterday.

Has the BOM declared Aus as under the influence of a modaki El Nino?


Edited by Petros (30/11/2018 18:23)

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#1477951 - 30/11/2018 18:40 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 8071
Loc: Maffra, Central Gippsland, Vi...
Windy currently shows good trades through Nino.3, doldrums in Nino.4 (I assume would be a westerly anomaly).

Looks to me like the tropical storm near the Solomons could stir up an enhanced WWB in the Kelvin wave generation zone?


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#1477952 - 30/11/2018 18:48 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: snowbooby]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 8071
Loc: Maffra, Central Gippsland, Vi...
Originally Posted By: snowbooby
Originally Posted By: Mike Hauber

The east is warming up and may soon overtake the west to make this an east based el nino,


Interesting paper
https://www.researchgate.net/.../2825200...rganizing_map..
[In case link does not work:The relationship between contiguous el nino and la nina revealed by self organising maps,Xin Li et al, Oct 2018]

Includes a table of enso events (nino&nina) 1951-2011 looking at transition between types EP,EP-like, CP and MIX
for Onset, Maturity and Decay stages
and finally a General categorisation.

Only 41% of cases did not transition from the onset type during at least one of the remaining 2 stages

Between Onset and Maturity, 50% of cases transitioned to a different type.

29% of events Onset as CP transitioned to EP or EP-like type at maturity.


Yet we are currently basing anomalies on 1985-2005?

How about we stop looking for analogues and just "look out the window" at the state of the oceans/atmosphere as they are today, compared to the trend over last 12 months or so. I have little confidence that the earths weather will ever replicate itself.


Edited by Petros (30/11/2018 18:49)

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#1477954 - 30/11/2018 18:58 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Mike Hauber]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 8071
Loc: Maffra, Central Gippsland, Vi...
Originally Posted By: Mike Hauber
El Nino, Modoki and convection:

Petros is right to note that the location of warmest water in absolute terms is quite important. This is where the tropical convection tends to focus, and this drives the general tropical circulation. Normally the warmest water is near Australia, and the water becomes steadily cooler as you go further east. This means convection is focused near Australia, and as these waters are firmly warmer than the rest of the Pacific it tends to stay there.

In a Modoki pattern waters near the dateline warm up somewhat. If they get close to the temps near Australia then the convection is not dominated by the Australian region, but spread between Australia and the dateline region, so convection near Australia weakens. If the anomalies further east are roughly equal or cooler, then the temperature east of the drop line still drops off at a moderate rate, and the area near the dateline doesn't have to share convection with the waters further east (but does share with the region nearer Australia). Hence cloudiness increases near the dateline, but does not increase further east.

In a classic el nino the anomalies get stronger towards the east, so the temperature becomes much closer to level across a much larger portion of the Pacific, and convection is then spread out over a much larger area of the Pacific and cloudiness increases well out into the Central and maybe even the East Pacific.

This year the strongest warm anomalies have tended to be near 170E. So convection stretched out towards 170E, there have been persistent cloudiness anomalies in this region and a tendency towards westerly anomalies near and to the west of 170E. Cloudiness, westerly anomalies, and SST anomalies are clearly linked in this region. As the anomalies further east have been weaker these waters haven't been warm enough to take a share in the tropical convection and cloudiness hasn't spread further east into the region the BOM monitors.


Your post makes sense Mike, but the current SatIR, imo, doesnt support you contention that the tropical activity extends from Aus to the dateline?:


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#1477958 - 30/11/2018 19:25 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Petros]
snowbooby Offline
Weather Freak

Registered: 11/05/2016
Posts: 275
Originally Posted By: Petros

How about we stop looking for analogues and just "look out the window" at the state of the oceans/atmosphere as they are today, compared to the trend over last 12 months or so. I have little confidence that the earths weather will ever replicate itself.


Perhaps it needs to be remembered that the whole impetus to the study of enso came about because of a desire to predict events because of the impact on human well being.

I don't agree that we should all sit at the window and note that things are today just the same as they were yesterday and make of our opinions as small a target as possible - you're welcome to do it as you choose.

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#1477960 - 30/11/2018 20:39 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Petros]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Originally Posted By: Petros


Your post makes sense Mike, but the current SatIR, imo, doesnt support you contention that the tropical activity extends from Aus to the dateline?:



Well I did say in a typical modoki it would stretch to about the dateline, over the last few months its been more like to about 170. Currently there is one low visible near 160 - the possible cyclone under discussion, and another low out near 180, although fairly weak. Some signs that the convection may be extending east although its currently the favorable part of the MJO cycle.

Interesting that both lows are forecast to (maybe) approach the coast, maybe a good sign for the season.

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#1478036 - 01/12/2018 18:23 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: snowbooby]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 8071
Loc: Maffra, Central Gippsland, Vi...
Originally Posted By: snowbooby
Originally Posted By: Petros

How about we stop looking for analogues and just "look out the window" at the state of the oceans/atmosphere as they are today, compared to the trend over last 12 months or so. I have little confidence that the earths weather will ever replicate itself.


Perhaps it needs to be remembered that the whole impetus to the study of enso came about because of a desire to predict events because of the impact on human well being.

I don't agree that we should all sit at the window and note that things are today just the same as they were yesterday and make of our opinions as small a target as possible - you're welcome to do it as you choose.


Understand your point SB.

But as I understand it, regardless of ENSO history, IOD's, PDO's et al, - the best climate model for accuracy, for the year ahead, is to simply average the previous 100 years, and base the predictions for the year ahead on that.

Cheap, and (for once) - no arguments.

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#1478157 - 02/12/2018 17:00 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Funkyseefunkydo Offline
Weather Freak

Registered: 30/04/2007
Posts: 906
Loc: East Lake Macquarie
Looks like thatís the end of the cut off lows. Also the 70hpa vortex has split on earth.null . Coincidence?

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#1478185 - 02/12/2018 20:10 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
ashestoashes Offline
Weather Freak

Registered: 22/10/2017
Posts: 739
Loc: Voyager Point (South West Sydn...
What's with all these storms over the WA inland given the Ningaloo Nina. How is so much moisture getting down there. Is the sheer level of heat over inland Aus causing Low pressure to dominate drawing in moisture?.



Also why does the West Aus coast see Upwelling with Southerly winds while the East Coast Downwelling with Southerlies. Ningaloo Nino/Nina study.

Also one more thing that Mike mentioned earlier that is seemingly going to eventuate that the pressure gradient over WA is going to drive psuedo-monsoon flow all the way to Nth Qld.

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#1478186 - 02/12/2018 20:19 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
If you have a high to the south and low to the north, you are pushing the air north but Coriolis force deflects the push and the air moves from east to west.

If you have southerly winds you are pushing the water north, but Coriolos force deflects the push and the water moves from west to east. On the west coast this is away from the coast and cold water has to well up to replace it. On the east this pushes the water towards the coast and you get downwelling.

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#1478189 - 02/12/2018 20:33 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Winter and Spring has finished, and the rainfall for this period shows a clear El Nino like signature.



We have now started summer and the rainfall influence of el nino in summer is pretty minor, unless you are in tropical Queensland. Or maybe modoki has a stronger influence later in the season that classic, although my search on this topic laterly hasn't come up with anything definite, and this event seems to be in the process of becoming less modoki like.

Final rainfall for November:



Very dry in tropical Qld, which is classic el nino for late spring/early summer.

The other area impacted in late Spring is far SE, especially Vic. It is unclear whether the impact ends in Oct or Nov, with Oct-Dec showing substantial impact, and Nov-Jan showing very little impact, suggesting much of the impact is in October. Rainfall for November in Vic was normal. Arguably a little early for influence to clear from this part of the country, but if it really is a month early clearing that doesn't seem particularly unusual to me.

Overall the rainfall for East Australia was 10mm below average for November. Some good rain in some areas was not enough to outweigh the dry conditions in others.

In contrast Northern Territory was 17mm above average, and South Australia 9mm above average. This is core IOD territory. IOD has been officially declared since September, and el nino has not been declared. Yet the rainfall matches el nino patterns, and does not match IOD patterns.

So what was that Coldfront about rainfall not being el nino like in November? And that I am looking in the wrong basin? I disagree.

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#1478193 - 02/12/2018 21:19 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
marakai Offline
Weatherzone Addict

Registered: 05/01/2006
Posts: 2270
Loc: Maryfarms NQ
One would think that boundary currents around/over both the northern continental shelves might have an effect as well.

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#1478197 - 02/12/2018 21:37 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
BIG T Offline
Weatherzone Addict

Registered: 24/01/2012
Posts: 1266
Loc: Albany Creek , QLD
Ok, never posted in here before, just wondering opinions of you lot if you think there may be drivers that we are not aware of as yet?

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#1478198 - 02/12/2018 21:39 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
marakai Offline
Weatherzone Addict

Registered: 05/01/2006
Posts: 2270
Loc: Maryfarms NQ
Yep Space Weather.

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#1478199 - 02/12/2018 21:45 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Mike Hauber]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 19046
Loc: The Beach.
Originally Posted By: Mike Hauber


I disagree.


There's a surprise laugh





Still looking in the wrong basin I see. I'm happy to explain what decile value the blue areas represent though if you like. The areas along coastal Qld in the tropics have strong variability in November in most years as it is pre-wet season. A quick look at that rainfall map shows the moisture came from the west ,not the Coral Sea. You're clutching again Mike.
_________________________


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#1478202 - 02/12/2018 21:58 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Mike Hauber]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 19046
Loc: The Beach.
Originally Posted By: Mike Hauber

So what was that Coldfront about rainfall not being el nino like in November? And that I am looking in the wrong basin? I disagree.


Originally Posted By: Mike Hauber
We are pretty much at the time of year where el nino influence on rainfall is negligible for everywhere except far north Qld.



You can't have it both ways Mike. Which one is it? Would you like me to give you some pointers on where Far North Queensland starts?

Originally Posted By: Mike Hauber
and this event seems to be in the process of becoming less modoki like.



What? In the 3-4 days since you were pushing a modoki ElNino? That's beyond priceless.

Originally Posted By: marakai
Sheesh Mike BOM is wrong and you are right ? Really ? And you accuse me of being a Climate denier ? Your fixation on WWB's and El-Nino is becoming a bit absurd considering that despite all climate indicators you are still clinging to a possible El-Nino to occur as ever, look outside your square for once and consider that there might just be something else out there driving things.


Glad I'm not the only one. In this case it's quite clearly the Indian ocean.

(my bold)
_________________________


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