AUSTRALIA’S BOM UPGRADES ENSO TRACKER STATUS TO EL NIÑO ALERT
On November 18, Australia’s Bureau of Meteorology (BOM) upgraded the conditions in the tropical Pacific from El Niño “watch” to “alert” levels, “indicating at least a 70% chance of El Niño occurring”. See the rest of their update here.
NOAA’S WEEKLY NINO3.4 DATA
The sea surface temperature anomalies of the NINO3.4 region of the equatorial Pacific are a commonly used ENSO index. NOAA’s Oceanic NINO Index is a form of the data of that region. According to NOAA’s weekly sea surface temperature data for the NINO3.4 region, as of the week centered on November 12th, El Niño conditions (+0.5 deg C or greater) have existed in the NINO3.4 region for 5 weeks and they are presently well above the threshold, now at 0.8 deg C for two weeks. This is still a far cry from the NOAA requirements to declare an “official” El Niño has taken place (5 consecutive periods of 3-month averages with NINO3.4 anomalies equal to or above the +0.5 deg C threshold). But it’s a start.
BE CAREFUL HOW YOU INTERPRET ANOMALIES ON MAPS
Over the past month or so, the unusual warming of the eastern extratropical North Pacific (known as “the blob”) has dissipated. Whether or not it will return next year is still uncertain. But as a result of the blob, there was a large volume of warm water on the surface in the northeastern North Pacific, and presently there are residuals (leftovers) that are now hugging the west coast of North America. See the map of sea surface temperature anomalies in Figure 1. It’s from the CMC Environment Canada webpage here.
Some of that warm water along the North American coast, according to the recent interviews with Trenberth and Timmermann, came from a coastally trapped Kelvin wave that formed after the large downwelling equatorial Kelvin wave hit the coast of Ecuador back in April 2014. Also see the discussion of coastally trapped Kelvin waves in the post Axel Timmermann and Kevin Trenberth Highlight the Importance of Natural Variability in Global Warming… And some of the warm is leftover from the blob.
That raises a few questions: is that warm water feeding back down to the tropics? If so, will it enhance the El Niño conditions in the tropics?
If we look at animations of sea surface temperature anomaly maps, it APPEARS that, yes, the warmer waters along the west coast of North America might be migrating southward along the California Current.
Animation 1 presents the 6 cells from the maps available as part of today’s animation from the CMC Environment Canada webpage here. That animation runs early October to today. The visual effect shows up pretty well on those maps. [Note: It could also be that the warming sea surfaces along the equator are creating a more typical El Niño spatial pattern.]
But in Animation 2 the visual effect isn’t as clear. Animation 2 shows 10 of the weekly cells of the animation here from the NOAA PSD Map Room webpage. They run from mid-September to mid-November.
Unfortunately, there is a large seasonal component to hemispheric sea surface temperature anomaly data, especially in the Northern Hemisphere. As a result, on sea surface temperature anomaly maps, the warmest anomalies can cycle yearly, tracking the change of seasons. Some of the seasonal appearance (not the blob) results from the seasonal loss and gain of Arctic sea ice, but there can still be large seasonal cycles in small regions…such as along the west coast of North America, where the California Current exists. See Figure 2.
That brings us to the questions: is the appearance of warm water migrating southward simply a product of the climatology used to determine the anomalies? Or is the warmer water actually heading south along the coast of North America as one might expect in the California Current?
Well, there’s something else to keep an eye on.
It is the lack of warm water pooling in the Western Pacific that should throw some caution into the wind, as I’d expect the equatorial countercurrent to help “fuel” an El Niño,” and there is little oceanic heat, at present, to transport!!!
tomwys1, depends on which reanalysis one looks at, as to whether there’s warm water in the warm pool:
From the NOAA webpage here:
This El Niño will be the most observed. Unprecedented.
I expect the record will be broken again next year; more people at looking in right direction.
“That raises a few questions: is that warm water feeding back down to the tropics? If so, will it enhance the El Niño conditions in the tropics?”
I think we should remember that we are talking about anomalies… Warm waters in higher latitudes aren´t “warm water” anymore if feeded back to the equator. So I think NO, it will not enhance the El nino conditions.
Arska seta, a positive anomaly means that it is warmer than normal.
Bob, i know. But you are talking about anomaly. Warmer than normal water in higher latitudes isn’t warmer than normal at El Nino area, if transported there…So the ocean currents doesn’t transport warm anomalies from high latitudes to equator.
Arska setä, I understand what you’re saying. But let’s look at this in a different light. Let’s say, for example, the sea surfaces normally warm 8 deg C from the start to the end of the California Current. If the water entering is warmer than normal, and if the warming rate from beginning to end remains constant at 8 deg C, then, when the warmer than normal waters reach the end, they would still be warmer than normal.
Bob, that would be the case in fully insulated system. But at the equator ocean temperature is at the equilibrium allready, so any “added heat” in form of slightly warmer than normal water (but still cooler than target area) is not affacting so straightforward as you said. I am not saying, that it is not affecting at all, but for example 1 degree anomaly in high latitudes isn´t anymore 1 degree at El Nino area.
Positive anomalies are generally transported only from low to high latitudes and also paraller in same latitude. This can be easily seen after every major El Nino – La Nina swing.
I wonder if this http://subseaworldnews.com/2014/04/25/jamstec-scientists-study-california-ninonina-anomaly/ will come into play.
I think it is pretty clear that we have a warm event in progress. Whether or not this qualifies as an El Nino is another story. The Blob made me think about an El Nino Modoki Type II which is more in line with how the Japanese see this evolving over two years.
This is an interesting graphic. http://origin.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbSSTSeaNormMaskInd6.gif It is for late spring early summer.
It makes me think the main event will be next winter and will be a Modoki.
Sig Silber, thanks for the link to the California Nino/Nina study. With respect to the weather model prediction, always keep in mind the spring prediction barrier.
If they keep on predicting an El Niño for long enough, then one day they’ll be right.
I think they are correct now if correct means some period of El Nino Conditions as defined by the ONI Index which on Thursday was reported as being 0.6. The problem in my mind is
A. Will this warm event last long enough to qualify as an El Nino and
B. Will it be significantly detectable in terms of weather impacts?
So far I am not that impressed. I think Bob Tisdale has been correct about this event from the start. It is a warm event. But not all warm events on the Equator qualify as an El Nino and not every El Nino has major impacts especially for the U.S.
Until last week Australia called it a “near-El Nino”. Now they classify it as “near or beyond” the El Nino threshold which is a tad more than the prior estimate.
I am not sure it matters much if this barely makes it or barely misses being an official El Nino. This raises the whole question of the criteria. I think in China and Japan they may put more emphasis on Nino 3 than Nino 3.4. Australia appears to require a higher SST anomaly to declare El Nino conditions. That may be related to what impacts Australia.
We may be too rigid with the criteria re the ONI and SOI. There may be more nuances than we usually think of re understanding what will impact our weather. I like a lot of the graphics that Bob Tisdale presents because they compare historical El Nino events and this warm event in ways that are not simply based on two numbers. I think that provides a more useful perspective. .
ENSO has more states than El Nino, La Nina and Neutral.