|Figure 1 | ENSO dial - derived from the Australian Bureau of Meteorology graphic.|
From the Australian Bureau of Meteorology (BoM):
The El Niño–Southern Oscillation (ENSO) in the tropical Pacific Ocean remains neutral (neither El Niño nor La Niña). Although some very weak La Niña-like patterns continue (such as cooler than normal ocean temperatures and reduced cloudiness in the central and eastern Pacific), La Niña thresholds have not been met. Climate models and current observations suggest these patterns will not persist. The likelihood of La Niña developing in the coming months is now low, and hence the Bureau’s ENSO Outlook has shifted from La Niña WATCH to INACTIVE.
BoM uses a mix of factors to determine whether or not an ENSO event is happening. These include (with extracts from BoM in italics):
- wind strength and direction - During La Niña events, there is a sustained strengthening of the trade winds across much of the tropical Pacific, while during El Niño events there is a sustained weakening, or even reversal, of the trade winds.
- sea surface temperature and pattern
- sea subsurface temperature and pattern
- cloudiness - Equatorial cloudiness near the Date Line typically increases during El Niño (below average OLR) and decreases during La Niña (above average OLR).
- and the Southern Oscillation Index (SOI), which is a calculation based on the pressure differences between Tahiti and Darwin (Tahiti minus Darwin). You can read more about the SOI on the BoM site, including the formula for its calculation.
Below is an animation showing the shift between El Niño, Neutral and La Niña, adapted from BoM:
|Figure 2 | Three phases of ENSO, showing trade winds and sea surface temperatures in the equatorial Pacific. Source: BoM (no longer on the BoM website).|
The Bureau has a nice simple description of the three phases of the El Niño–Southern Oscillation (ENSO), with more detailed illustrations, including what's happening below the sea surface. There's also a HotWhopper article which goes into a fair amount of detail.
Deniers won't like this much...
Science disinformers won't like it much, that there's no impending La Niña. They are aching to get back to a "pause"or, preferably, an ice age. Alleging fraud and fakery of temperature records doesn't work with rational people, when all the temperature data sets show similar results. To claim that the entire body of meteorology and climatology professionals all around the world are fudging data, just makes the claimant look like an utter conspiracy nutter.
Only six days ago, Anthony Watts put up some pictures of global sea surface temperatures (archived here) and wrote:
Also note the strong La Niña pattern in blue across the Pacific equatorial region in the top panel, along with the many other areas of below normal SST. Since SST tends to drive global air temperatures, it looks like 2017 might be a colder year globally if this keeps up.Two things - first there was no "strong" Niña pattern at all. Have a look for yourself. The map below shows sea surface temperature anomalies for the end of November, in the strong La Niña of 2010. Focus on the equatorial Pacific, in the centre of the map. The deeper the blue, the cooler it is compared to "normal". The redder, the warmer. Slide the bar across the image to reveal the sea surface temperature anomalies at the end of November 2016. (To reset, click on the arrow at the bottom right.)
From the map above, all there is this year is a shaky weak bit of cooler than normal temperatures in the equatorial Pacific, surrounded by hotter than normal seas. Quite unlike the strong La Niña in 2010.
The second thing is that Anthony acts as if he's surprised that next year may not be as hot globally as it has been this year. He wrote: "it looks like 2017 might be a colder year globally if this keeps up". He should keep up with what the scientists have been saying. This year will be a record warm year. Next year is unlikely to be yet another record. Three record hot years in a row is unusual enough. To get four in a row would be extremely unusual. It could happen, but probably not.
Keep an eye out for Gavin Schmidt's tweets. He predicted way back in April this year that 2016 would be another "hottest year on record". (He said he nearly made public his prediction in March.) Back in March this year, he also pointed out that temperatures would go down in the latter part of this year "as the El Niño effect wears off".
@artinia that isn't justified yet. Anomalies will go down later this year as the El Niño effect wears off.— Gavin Schmidt (@ClimateOfGavin) March 15, 2016
That second point is important because lately a favourite disinformer bit of fakery is that scientists didn't predict that temperature anomalies would fall after the strong El Niño. That is plain weird. Disinformers wouldn't have heard of ENSO if not for scientists. Nor would they have understood that El Niño causes the world to warm while in a La Niña, global temperatures go down a tad.
Addendum: Since 1950, only 3 of the 8 strongest El Ninos were followed by La Nina
By the way, contrary to some popular opinion, in recent decades more often than not, a strong El Nino is not immediately followed by a La Nina. Since 1950 only 3 of the now 8 strongest El Ninos were immediately followed by a La Nina. Here are a couple of previous HotWhopper articles to illustrate:
- Weather Reality Check: What a La Niña looks like...in pictures - September 2016
- El Niño to La Niña years - May 2016
- Anthony Watts sticks his neck out and predicts La Niña - March 2016