Guest Post by Bob Tisdale
Weekly NINO3.4 Sea Surface Temperature Anomalies from NOAA Are Approaching the Threshold of a Moderately Strong La Niña. Australia’s Southern Oscillation Index from BOM is in La Niña values. And NOAA’s Multivariate ENSO Index is Still in ENSO Neutral Territory.
NOAA’S WEEKLY NINO3.4 REGION SEA SURFACE TEMPERATURE ANOMALIES
NOAA’s weekly sea surface temperature anomalies for the NINO3.4 regions (based on the original Reynolds OI.v2 data) are furnished on Mondays. The most recent update for the week centered on October 6, 2016 shows the sea surface temperature anomalies of the NINO3.4 region (5S-5N, 170W-1250W), which NOAA uses to define a La Niña and its strength, is at -0.9 deg C, well below the -0.5 deg C threshold of La Niña conditions and approaching the -1.0 deg C threshold of a moderately strong La Nina.
Figure 1
The weekly NINO region sea surface temperature anomaly data for Figure 1 are from the NOAA/CPC Monthly Atmospheric & SST Indices webpage, specifically the data here. The anomalies for the NOAA/CPC data are referenced to the WMO-preferred base years of 1981-2010.
The top graph in Figure 1 includes the weekly sea surface temperature anomalies of the NINO3.4 region of the equatorial Pacific, which is bordered by the coordinates of 5S-5N, 170W-120W. The sea surface temperature anomalies for the NINO3.4 region are commonly used (especially by NOAA) as an indicator of the strength, timing and duration of El Niño and La Niña events. And for the bottom graph, the evolutions of the sea surface temperature anomalies in 2015 and 2016 are compared to 1997/98, for comparison to the transition from another very strong El Niño.
BOM’S SOUTHERN OSCILLATION INDEX
The Southern Oscillation Index (SOI) from Australia’s Bureau of Meteorology is another widely used reference for the strength, frequency and duration of El Niño and La Niña events. We discussed the Southern Oscillation Index in Part 8 of the 2014/15 El Niño series. It is derived from the sea level pressures of Tahiti and Darwin, Australia, and as such it reflects the wind patterns off the equator in the southern tropical Pacific. With the Southern Oscillation Index, El Niño events are strong negative values and La Niñas are strong positive values, which is the reverse of what we see with sea surface temperature-based indices. The September Southern Oscillation Index value is +13.5, which well above the threshold of La Niña conditions. (The BOM threshold for La Niña conditions is an SOI value of +7.0. See the BOM webpage here.)
Figure 2
The top graph in Figure 2 presents a time-series graph of the SOI data. Note that the horizontal red blue line is the present monthly value, not a trend line. The bottom graph in Figure 2 compares the evolution of the SOI values in 2015/16 to those in 1997/98.
Also see the BOM Recent (preliminary) Southern Oscillation Index (SOI) values webpage. The current 90-day average is cycling just above the +7.0 threshold of La Niña conditions.
Regardless of the SOI being in La Niña conditions, the BOM is still in a La Niña Watch. This may be caused by the BOM using the outdated base years of 1961-1990 for sea surface temperature anomaly-based indices.
THE MULTIVARIATE ENSO INDEX
The Multivariate ENSO Index (MEI) is another ENSO index published by NOAA. It was created and is maintained by NOAA’s Klaus Wolter. The Multivariate ENSO Index uses the sea surface temperatures of the NINO3 region of the equatorial Pacific, along with a plethora of atmospheric variables…thus “multivariate”.
According to the most recent Multivariate ENSO Index update discussion, the tropical Pacific is still in ENSO Neutral conditions:
Compared to last month, the updated (August-September) MEI has dropped further to -.10 (down by 1.1 in last three months), which translates into ENSO-neutral rankings.
There’s something else to consider about the MEI. El Niño and La Niña rankings according to the MEI aren’t based on fixed threshold values such as +0.5 for El Niño and -0.5 for La Niña. The MEI El Niño and La Niña rankings are based on percentiles, top 30% for the weak to strong El Niños and the bottom 30% for the weak to strong La Niñas. This is difficult to track, because, when using the percentile method, the thresholds of El Niño and La Niña conditions vary from one bimonthly period to the next, and they can change from year to year.
The Multivariate ENSO Index update discussion and data for August/September were posted on October 8th. The top graph in Figure 3 presents a graph of the MEI time series starting in Dec/Jan 1979. And the bottom graph of Figure 3 compares the evolution in 2015/16 to the reference El Niño of 1997/98.
Figure 3
WANT TO LEARN MORE ABOUT EL NIÑO AND LA NIÑA EVENTS AND THEIR AFTEREFFECTS?
I published On Global Warming and the Illusion of Control (25MB .pdf) back in November. The introductory post is here. It’s free. Chapter 3.7 includes detailed discussions of El Niño events and their aftereffects…though not as detailed as in Who Turned on the Heat?
My ebook Who Turned on the Heat? – The Unsuspected Global Warming Culprit: El Niño-Southern Oscillation (23MB .pdf) goes into a tremendous amount of detail to explain El Niño and La Niña processes and the long-term aftereffects of strong El Niño events. It too is free. See the introductory post here. Who Turned on the Heat? weighs in at a whopping 550+ pages, about 110,000+ words. It contains somewhere in the neighborhood of 380 color illustrations. In pdf form, it’s about 23MB. It includes links to more than a dozen animations, which allow the reader to view ENSO processes and the interactions between variables.
http://sites.uci.edu/zlabe/files/2016/10/sit_PIOMAS_mask.gif
Do you have any animations for any periods prior to 1979?
Eg, http://mclean.ch/climate/Arctic_1920_40.htm
This is a satellite record Dennis. Pretty unambiguous isn’t it? Unless there is a remarkable turnaround, Whacky old Wadhams might be close to the mark after all.
Great post on JoNovas site, showing Oz BOMs projection from August predicting above average temperatures all over Australia for September. Beside it is Oz BOMs actual for September showing average to mainly well below average temepratures all over Australia.
But we can say with absolute confidence what will happen 20,50,100 years out, pretend that we can control it, and spend vast amounts of money on futile projects (that mostly dont work anyway). Its a mad world.
It’s not the scientists who are expressing anything remotely like “absolute” confidence Yerpos. That is a straw man argument and is the preserve of others who post here.
Even a cursory glance at SST anomaly maps revealed a distinct cooling in the 3.4 centered around Oct 1. Man’s understanding of Oceanic change is very early, and very
primitive.
This may be viewed as an extrapolation of what Bob Tisdale presents us here.
Below you see the plots for five ENSO indices JMA ENSO, MEI, Nino3.4, ONI and SOI during the periods
– jan1997 – aug 1998
– jan 2015 – aug 2016
All plots are relative to their january start to completely offset the difference between the periods, and therefore begin all at zero.
Moreover, since the indices have different value ranges, they were scaled to fit (but of course, the two periods are scaled the same way for all indices). SOI is inverted (La Niña has positive values here).
The scaling was made such that for each of the five indices, the real value at the peak in 1997/98 has been scaled to 1.0. So we not only avoid to compare apples with oranges, but also to compare apples of too different size:
http://fs5.directupload.net/images/161012/2r5ldgq4.jpg
You can easyily observe that all five indices show, for 2015/16, a level below their level of 1997/98.
In dark bold you see the respective mean of all index values for the two periods.
Some might argue about this method and complain that ENSO phenomena aren’t bound to a fixed period. This is correct, especially for BOM’s SOI which for example had a very late peak in 1998.
But calculating and comparing the averages of all index values above zero, or of those values superseding a given level, shows the same result.
Finally, one could draw the plots of various temperature series ( troposphere, radiosondes, surface) for the same periods, and constructed in a similar manner.
Here also you would observe that apart from UAH6.0beta5 which acts here as the exception confirming the rule, all temperature records show, relatively to their january, 2015/16 clearly below 1997/98.
And the temperature level differences between the two periods are even higher (for UAH as well) when ENSO’s main activity corner, the Tropics, is considered (here for the troposphere only):
http://fs5.directupload.net/images/161013/klxbsw4m.jpg
I think this winter could be very interesting. El nino more modeki, not quite as much heat to the troposphere as 98, la nina winds more intense? If the left over warm water and weak circumpolar vortex interact, we may some craziness in the arctic.