The sea temperatures are achanging.
A La Nina now expected? - how big?
The subsurface temperature anomalies say we are going rapidly into La Nina conditions.
This colder water will circulate up into the Nino regions in a month or two. The anomalies are a little ahead of the schedule that produces El Ninos and La Ninas as the typical peak is November to January. They will need another surge/replenishment of cooler waters to produce a big La Nina. Otherwise, a smaller one lasting into the fall (off-normal-peak; only 20% of events are off-peak).
Looks like a big La Nina event about to start.
And the experts concur..,.
•A transition from El Niño to ENSO-neutral is underway.•Sea surface temperatures are decreasing across much of the Pacific Ocean.•Based on current observations and dynamical model forecasts, a transition to ENSO-neutral conditions is expected by June 2010, which will continue into the Northern Hemisphere summer 2010.•Although many models predict ENSO-neutral conditions, there is a growing possibility of La Niña developing during the second half of 2010.
The La Nina is already starting according to yesterday's SST maps.
Well CFS has us in a moderate La Nina by July;
That will be some switch if that comes off.
Here is the forecast from last year at this same time. Nino 3.4 made it to 1.9C in Mid-december so only the Nasa GMAO model and the COLA CCM3 was close from this point in the year.
While as time went on, last year's forecasts got more accurate, one has to look at these forecasts over time to see if they are accurate and they are not.
Last year at this time, I was already calling for an El Nino
Here is the ensemble forecast for the ENSO today. Nino 3.4 this week is already in the -0.7C territory so no model is accurate even for the date of publication for this forecast which was May 20th.
But a La Nina is certainly coming/here now.
One thing we can be sure of - the upcoming La Nina looks like being yet another mid-ocean event rather than an Eastern Pacific phenomenon, just like the last few El Ninos (although the 2008 LN was more Eastern-based).
This has implications for the circulation as if there's still warmish water off South America by late summer despite a rapid switch to la Nina in Nino 3.4, the effect on the Atlantic hurricane season might be different from what's expected.
Normally a post-El Nino pattern with a shift to La Nina means a killer combination of low wind-shear and high Atlantic SSTs, but it may be that wind shear remains more Nino-esque during the hurricane season unless the La Nina shifts Eastwards.
Updated for month of April (but not the most recent -0.85C weekly anomaly). Nino 3.4 follows Eq. Upper Ocean Heat Content with a lag of about 1 month.
Latest ECMWF forecast seems to think so too:
Doesn't look to be particularly strong though, but we'll see.
There is a pretty good correlation but other ocean indices are just as or more important. I've modeled all the different temperature series based on the growth in CO2, the ENSO, the AMO and the southern Atlantic's version of the AMO. The ENSO by itself does not explain enough of the variation and has an impact of only +/- 0.2C (or a change of 0.4C from a large El Nino to a large La Nina).
(I like the super El Ninos of 1997-98 and 1877-78).
The ENSO's correlation to global temperature is widely accepted and has a more-or-less predictable impact on temperatures which is why we should be watching it. The formula is Global Temp C = 0.08 * Nino 3.4 index (of 3 months previous) [the C change from month to month will be the change in Nino 3.4 of 3 months previous].
The Nino 3.4 Index came in at -0.03C in May and has fallen to -0.4C for the week ending June 2nd.
The Equatorial Upper Ocean Heat Anomaly in April was -0.06C, fell to -0.96C in May and is about -1.2C in the week of June 2nd. [These numbers lead the ENSO by about 1 month].
So the prediction of a Nino 3.4 being close to Zero in May was correct and my best estimate for June is about -0.9C.
There is more than enough cooler than normal subsurface water to drive a La Nina into the late fall.
Here is a bunch of charts (all updated for the May data) which shows how the ENSO is part of one big system which includes the:
- Equatorial Upper Ocean Heat Anomaly,
- the Equatorial surface and subsurface ocean currents which flow east-west at the surface with the prevailing winds and then flow west-east at about 150 metres depth back underneath the ENSO regions to the beginning of the regions at the Galapogos Islands which then recirculates across the surface once again,
- the Trade Winds at the Equator which blow east-west and drive the east-west surface ocean currents. When the Trade Winds slow down there is an El Nino. The surface currents slow down, the water gets heated day after day by the equatorial Sun, warmer water from the Pacific Warm Pool area slosh backwards into the ENSO region, cooler waters from below cannot surface. The Equatorial Upper Ocean Heat Anomaly plays a large role in the strength of the Trade Winds it seems. Warm anomalies help slow down the winds (rising air currents), cool anomalies help speed up the Winds.
- Atmospheric Angular Momentum which is driven by mid-latitude winds mostly but which provides an extra push/pull on the Equatorial Trade Winds, The Length of the day actually changes by a millisecond or so through the AAM.
- Outgoing Long-Wave Radiation which is actually opposite to that expected - OLR FALLS during an El Nino and rises during a La Nina, this is driven by clouds which greatly multiply during an El Nino and hold the heat-in in the atmosphere, During a La Nina, there is much less clouds and whatever heat the Equatorial Oceans have is quickly lost to space.
- The OLR effect is really how the ENSO transfers its heat or lack of it to the rest of the globe; the prevailing winds are east-west across the tropics so the entire tropics are warmed first through an El Nino. Other winds flow toward the north and make it first to northern North America and the Arctic. These are the regions which are most impacted by the ENSO.
- the Southern Oscillation Index which is influenced by the OLR and the Trade Winds and the cloud patterns. Pressure falls at Tahiti at the end of the Nino regions during a El Nino (rising air columns and clouds) while it rises at Darwin because there is less cloud cover there and less moisture delivered to the region from the Equator.
Edited by user 09 June 2010 03:09:26(UTC)
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CFS takes SST's down to around -1.8 in region 3.4 by next month;
So by July we're already pretty much in a strong La Nina category if this forecast is correct.
The cross-sections of the Equatorial Pacific show a strong La Nina is on its way very soon.
At 0 degrees in the Nino regions (from 165E to 90W), there is more cool anomalies than I have seen before.
If you want to see the staying power of the La Nina, these anomalies at 140W and 0N and 100 metres depth take about 3 to 6 months to make their way to 25 metres depth at 100W when they start to influence the surface temperatures (they never actually make it all the way to the surface).
There are some areas which are -7.0C.
Further staying power can be observed at 165E 0N at 200 metres depth (where La Ninas or El Ninos are born in my opinion), which take about 6 to 9 months to make their way to 100W 25 metres deep and start influencing the surface. There are anomalies here which are -2C. So there is enough cooler than normal water to extend a La Nina into the Fall at least.
[The warm anomalies on the side are typical after-affects of the past El Nino. The ENSO waters recirculate at 8N to 10N and 8S to 10S as a countercurrent after the ENSO so these areas usually reflect the most recent ENSO event. The deeper anomalies also circulate the opposite direction (east-west) to those at the Equator. The surface currents at these latitudes also flow backwards to that at the Equator (west-east) and especially on the northern side - the North Equatorial Counter-Current which seems to be much stronger than its southern cousin. ]
All these charts look exactly opposite last year at this time in the lead up to the El Nino.
Here it comes and it could be a biggy......
Interesting about Cloud cover, coincidence or a connection to Cosmic rays and sun spots? Which apparently has been concluded "by some" not to be possible. something else we know little about it appears.
Taken off the Roy Spencer site....................................
June 18th, 2010 by Roy W. Spencer, Ph. D.
Sea Surface Temperatures (SSTs) measured by the AMSR-E instrument on NASA’s Aqua satellite continue their plunge as a predicted La Nina approaches. The following plot, updated through yesterday (June 17, 2010) shows that the cooling in the Nino34 region in the tropical east Pacific is well ahead of the cooling in the global average SST, something we did not see during the 2007-08 La Nina event (click on it for the large, undistorted version):
The rate at which the Nino34 SSTs are falling is particularly striking, as seen in this plot of the SST change rate for that region:
To give some idea of what is causing the global-average SST to fall so rapidly, I came up with an estimate of the change in reflected sunlight (shortwave, or SW flux) using our AMSR-E total integrated cloud water amounts. This was done with a 7+ year comparison of those cloud water estimates to daily global-ocean SW anomalies computed from the CERES radiation budget instrument, also on Aqua: What this shows is an unusually large increase in reflected sunlight over the last several months, probably due to an increase in low cloud cover.
At this pace of cooling, I suspect that the second half of 2010 could ruin the chances of getting a record high global temperature for this year. Oh, darn.
Edited by user 20 June 2010 23:14:08(UTC)
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The La Nina continues to strengthen. The Nino 3.4 Index is about -0.6 right now.
One issue is there is still relatively warm water in the North Equatorial Counter-Current at 3N to 5N (which is technically the warm water left-over recirculated from the last El Nino). So the cooler Equatorial La Nina waters are slowing cooling this warmer current off and it is creating little eddies (well little for the ocean but still very large) which have one side cooler and the other warmer which is why the cool water in the chart below has the spikes in it.
Some areas are as low as -2.2C in the Nino regions. The North Atlantic, however, is very warm and I think it has a slightly bigger impact than the ENSO has.
The Pacific cross-sections show that the ocean below is quite a bit cooler than it was 1 month ago and this La Nina could become a very long-lasting strong event.
At 140W, some of the 5S to 5N ribbon which circulates up into the Nino regions is as cool as -9C.
As much as I am not a fan of NASA GISS, the ENSO forecasting model run by the Goddard Space Flight Centre in Maryland [NASA GMAO] seems to best model based on the track record over time ...
... and they are now predicting this event will become the first Super-La Nina ever.
Edited by user 24 June 2010 15:24:41(UTC)
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