Bob Tisdale on Climate Change and Global Warming Blog
By Bob Tisdale
Thursday, June 10, 2010
La Niña Is Not The Opposite Of El Niño – The Videos
http://i46.tinypic.com/2zqznnn.jpg
Figure 1 – Sample Animation – Not Used In Video
Recently, I began animating maps that represent 12-month averages of “noisy” datasets with good results. The weather noise and seasonal variations are gone, for the most part. The 12-month-averaged TLT anomaly maps present a much “smoother” animation, as shown in the .gif sample, Figure 2.
http://i48.tinypic.com/2gt6slz.jpg
Figure 2 – Sample Of Animation Used In Video
In the video, I liken the effect to smoothing the data in a time-series graph with a 12-month filter, Figure 3.
http://i48.tinypic.com/160wk1w.jpg
Figure 3 – Smoothed Time-Series Graph
VIDEO DESCRIPTION
The following 2-part video series provides detailed descriptions, time-series graphs, and animations of the processes that take place during El Niño and La Niña events. It uses TLT, SST, Total Cloud Amount, Sea Level, and Downward Shortwave Radiation anomalies to help illustrate the significant differences between the 1997/98 El Niño and the 1998/99/00/01 La Niña.
The videos also help illustrate why the effects of ENSO cannot be removed from the global surface temperature record by simply subtracting scaled and lagged NINO3.4 SST anomalies (or another ENSO index) from global temperature anomalies. There are significant residuals that contribute to global temperature anomaly trends, and these residuals are not accounted for with the simple methods used in climate studies such as Thompson et al (2009). Link (with paywall) to Thompson et al (2009):
http://journals.ametsoc.org/doi/abs/10.1175/2009JCLI3089.1
I’ve also included animations that compare global SST anomalies with the other datasets. A sample frame that compares SST and TLT anomalies is shown in Figure 4. To indicate the timing of the maps as they proceed from El Niño to La Niña, many of the animations also include time-series graphs that fill in as time progresses.
http://i49.tinypic.com/2yl22bk.jpg
Figure 4 – Sample Frame From Animation Of Two Datasets
THE VIDEOS
Please view the animations full screen and, if possible, in high definition.
Part 1
YouTube Link
http://www.youtube.com/watch?v=Et3wjKKCy5o
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Part 2
YouTube Link
http://www.youtube.com/watch?v=A6bmb8hi6u0
SOURCES AND DATASETS
The maps were created using the map-making feature of the KNMI Climate Explorer, which was also used for the data in the time-series graphs.
http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere
The primary SST and SST anomaly data used in the animations and graphs are NOAA/Reynolds Optimum Interpolation (OI.v2) SST.
http://www.emc.ncep.noaa.gov/research/cmb/sst_analysis/
For the comparison to tropical Pacific Ocean Heat Content, a longer-term SST dataset was required, and for that graph, I used Kaplan/Reynolds (OI.v2) NINO3.4 SST anomalies from the Monthly climate indices webpage of the KNMI Climate Explorer. Link to Kaplan overview:
http://www.cgd.ucar.edu/cas/guide/Data/kaplan_sst.html
The other datasets used in the videos are also available through the KNMI Climate Explorer and they include:
1. International Satellite Cloud Climatology Project (ISCCP) Total Cloud Amount data. Link:
http://isccp.giss.nasa.gov/projects/flux.html
2. CAMS-OPI [Climate Anomaly Monitoring System (“CAMS”) and OLR Precipitation Index (“OPI”)] precipitation data. Link:
http://www.cpc.noaa.gov/products/global_precip/html/wpage.cams_opi.html
3. RSS MSU Lower Troposphere Temperature (TLT) anomalies. Link:
http://www.remss.com/msu/msu_data_description.html
4. CLS (AVISO) Sea Level anomalies. Link:
http://www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/
5. NCEP/DOE Reanalysis-2 Surface Downward Shortwave Radiation Flux (dswrfsfc) anomalies. Link:
http://www.cpc.ncep.noaa.gov/products/wesley/reanalysis2/kana/reanl2-1.htm
There is also an animation of the Equatorial Subsurface Temperature Cross-sections that are available through the ECMWF website:
The Trade Wind Index (5S-5N, 135W-180) Anomaly data is available through the NOAA CPC website. Scroll down to the second grouping for the anomaly data:
http://www.cpc.noaa.gov/data/indices/wpac850
FURTHER DISCUSSIONS
The first detailed posts on the multiyear aftereffects of El Nino events are:
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 1
And:
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 2
And:
Supplement To “Can El Nino Events Explain All Of The Warming Since 1976?”
And:
Supplement 2 To “Can El Nino Events Explain All Of The Warming Since 1976?”
The impacts of these El Nino events on the North Atlantic are discussed in:
There Are Also El Nino-Induced Step Changes In The North Atlantic
And:
Atlantic Meridional Overturning Circulation Data
The Lower Troposphere Temperature (TLT) anomaly responses are discussed in:
RSS MSU TLT Time-Latitude Plots… Show Climate Responses That Cannot Be Easily Illustrated With Time-Series Graphs Alone
And:
El Ninos Create Step Changes in TLT of the Northern Hemisphere Mid Latitudes
The misrepresentation of ENSO in climate studies are discussed in the following (The discussions are similar but there are differences in the presentation):
Climate Studies Misrepresent The Effects Of El Nino And La Nina Events
And:
The Relationship Between ENSO And Global Surface Temperature Is Not Linear
And:
Multiple Wrongs Don’t Make A Right, Especially When It Comes To Determining The Impacts Of ENSO
And:
Regression Analyses Do Not Capture The Multiyear Aftereffects Of Significant El Nino Events.”
Posts related to the effects of ENSO on Ocean Heat Content are here:
ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data
And:
North Atlantic Ocean Heat Content (0-700 Meters) Is Governed By Natural Variables
And:
North Pacific Ocean Heat Content Shift In The Late 1980s
Detailed technical discussions can be found here:
More Detail On The Multiyear Aftereffects Of ENSO – Part 1 – El Nino Events Warm The Oceans
And:
More Detail On The Multiyear Aftereffects Of ENSO – Part 2 – La Nina Events Recharge The Heat Released By El Nino Events AND…During Major Traditional ENSO Events, Warm Water Is Redistributed Via Ocean Currents.
And:
Posted by Bob Tisdale at 9:32 AM
vukcevic asks: “Has El Nino link(ed) to the Earth’s magnetic field changes?”
I see no evidence other than an apparently accidental association, so far. Thanks, though. I find your comments interesting.
Bob, when you say
“One thing is certain: there are ENSO residuals that are not accounted for using the methods of Thompson et al, and those residuals add to the positive trend.”
am I right to read this as “account for some of the positive trend found by Thompson et al” ? ie that because the decay of temp in the west takes many years – 9 to 11 was it – there is a cycle which blurs the trend and makes the linear trend unreliable, especially as a projection or to conclude its all due to CO2?
Presumably, analysis over longer timescales should reveal any net temp trend, but if Oceans absorb and release heat over even longer timeframes, how does anyone know what’s going on unless we know ALL the cycles involved, the scale of each of the effects and how they mesh (phase) together to affect “our” temperatures?
Excuse if these are superficial observations, I don’t pretend to deep knowledge but do wonder in view of the oceans’ heat capacity and complexity, how others can be so certain of what’s going on in the total climate system…
Last but not least: If you lie down with kids, you’ll get up peed. ☺
jorgekafkazar says:
June 11, 2010 at 11:25 am
Yes, to say that would be blasphemous, but times are changing you know…
As the earth rotates from west to east the current order would be La Niña, but circulation goes clockwise when El Niño appears. Curious, isn´t it?
vukcevic says:
June 11, 2010 at 5:05 am
Has El Nino link to the Earth’s magnetic field changes ?
http://www.vukcevic.talktalk.net/LFC20.htm
El Niño/La Niña: opposed polarities.
Geoff Sherrington says: “Bob, you describe a plausible set of related cycles. However, you seem to need to do difficult things, like push warm water to depth, so it can later rise to give surface heat. ”
Maybe it’s my description. During La Nina and ENSO-neutral phases, the trade winds push warm surface water from east to west. In the west it encounters land mass and it “piles up”. It is physically higher in the west than in the east. Some of the height difference is caused by the temperature difference, but some of it is caused by the trade winds pushing the water to the west. When the trade winds relax, gravity causes the warm water (that had accumulated in the west) to travel to the east.
Let’s look at it another way. By pushing surface waters from east to west during ENSO-neutral phases, the trade winds create a temperature gradient, where the surface waters are cooler in the east than they are in the west. This can be seen in a temperature profile of equatorial Pacific SST (not anomalies) at the various longitudes. The temperature difference between east and west is more than 4.5 deg C during ENSO-neutral periods:
http://i49.tinypic.com/33tms61.jpg
The next illustration shows the equatorial Pacific temperature profile at the peak of the 1997/98 El Niño and at the first peak of the La Niña that followed.
http://i48.tinypic.com/24deio1.jpg
The temperature difference between east and west drops to approximately 1.7 deg C during the El Niño because the trade winds have allowed the warmer waters in the west to slosh to the east. The temperature difference between east and west increases to 6.9 deg C during the La Niña, because the trade winds are stronger than they are during ENSO-neutral months.
There are also equatorial surface and subsurface ocean currents that come into play, Geoff. I wrote a post on the surface currents portion that also includes a video:
http://bobtisdale.blogspot.com/2009/02/equatorial-currents-before-during-and.html
Did these explanations overcome your concerns? And did they help answer the other questions from your comment?
chris y says: “The visualizations provide an excellent tool to help understand the changes in ocean surface temperatures and, in particular, sea level.”
Curious how, in the video, the sea level anomalies at the height of the 1998/99/00/01 La Nina resemble the map of the change in sea level anomalies from 1992 to 2009 located at the bottom of the AVISO webpage:
http://www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/
Layman Lurker says: “The filtered/smoothed images in the video are a great innovation. Was this your idea or are others doing this as well?”
I’ve never seen it done before.
You asked, “Are there some unique physical characteristics of the PWP area (like ocean depth, etc.) which make this area of the tropical Pacific more “warmable”, and therefore more prone to variability (due to tsi or cloud variability)?”
I believe it’s due to a couple of factors. There’s the breadth of the tropical Pacific. It circles almost half of the globe. Also, the trade winds push the surface waters in the tropical Pacific (that have been warmed by the sun) from east to west, but then they encounter the Indonesia land mass and “pile up” there in what is called the Pacific Warm Pool.
You asked, “Would detrended SST’s still leave these ENSO residuals?”
What subset of the global oceans are you asking about, or are you asking about detrending global SST anomalies?
Enneagram says: “When there is a LA NIÑA, there is not a southward warm current running along the northern coasts of Peru, instead the usual Humboldt´s current running from antarctica northwards along the west southamerican coast.”
I’m not sure what you’re driving at, Enneagram. Where in this post or video did I write or imply that there was a “southward warm current running along the northern coasts of Peru” during a La Nina.
jorgekafkazar: You quoted Stephen Wilde, “The question of causation remains open however and in particular the question as to whether the ENSO phenomenon is itself a climate driver causing air circulation changes or whether the air circulation changes drive ENSO.”
Then you wrote, “I vote for the former, with the air circulation changes driving LaNiña, in turn. ”
ENSO is a coupled ocean-atmosphere process–a chicken and egg process. The trade winds cause the temperature difference between the eastern and western tropical Pacific, and the temperature difference between the eastern and western tropical Pacific causes the trade winds.
Pamela Gray: Thanks for the link.
Keith in Hastings UK: You asked, “am I right to read this as ‘account for some of the positive trend found by Thompson et al’ ? ie that because the decay of temp in the west takes many years – 9 to 11 was it – there is a cycle which blurs the trend and makes the linear trend unreliable, especially as a projection or to conclude its all due to CO2?”
Papers like Thompson et al don’t account for the atypical response of the East Indian and West Pacific Oceans with their simplistic analysis. While the temperatures in the East Indian and West Pacific Oceans are elevated, they are mixing with the other portions of those oceans. This causes the SST anomalies in the East Indian and West Pacific to drop and the SST anomalies in the adjacent portions to rise. In turn, this causes the trend in global SST anomalies to differ from the NINO3.4 SST anomaly trend. But papers like Thompson et al assume that all of the difference is caused by greenhouse gases. (They also miss the Atlantic Multidecadal Oscillation, but that’s another matter entirely.)
You continued, “Presumably, analysis over longer timescales should reveal any net temp trend…”
But that trend has been biased upwards by the atypical response of the East Indian and West Pacific Oceans.
Regards
On December 20 of 1998, as we left Autumn, it was snowing (and to be fair, not sticking) at sea level in the San Francisco Bay Area. The animation makes it apparent how that happened.
Bob, thanks for another outstanding post. As others have exclaimed, the videos are most informative. I need to watch them several times to absorb the information content. At this moment, I’m unable to ‘see the linkage’ between PDO and El Nina/El Nino.
Job well done …
Paul Coppin says: “A note to tech article writers and wannabe writers everywhere: define your acronyms in first use, regardless of whether you think you are talking to your confreres or not.”
Sorry. I jumped right into the use of TLT. I’m usually better at defining acronyms.
Detrend global SST anomalies, but you would look for the residuals in the applicable ocean subsets. Would this not confirm the rebuttal of Thompson et al that you are implying?
Thank you Bob, there is a lot to take in of your fine work. Asking the right questions is a challenge (for me anyway).
I will jump in.
1. With the trade winds moving water to the western pacific during La Nina, does the relatively shallow water around Indonesia and Australia/New Guinea form a barrier to this water moving to the Indian Ocean ? (It appears so to me).
2. Does the Indian Ocean Dipole play a part in this cycle ?
Surprised that anyone could think they are opposites to start with. Just because they happen one after the other doesn’t make them some sort of oceanic Summer/Winter thing…
Just two obvious examples of the coupled and chaotic forces controlling the climate.
Bob, Thanks for the answer. It is almost complete re my questions, but I’m still searching for your impression of the ultimate source of energy that pushes the water around, etc. Is it as simple as the rotation of the Earth creating surface/air friction?
Please no not get an impression I’m knocking your work, I’m not – I’m just seeking education.
I continue to study the “hot 1998 year” and your visualisations help. In some other data, it seems to show globally as a sharp heat pulse about January 1998, with perhaps another about April 1998. It does not seem to spread from an identifiable locus, so to me it remains a mystery. However, within that mystery there might well lurk some important fundamentals. I explore short term anomalies, your preference is for longer events, but there’s a place for both.
Thank you.
Geoff Sherrington says: “It is almost complete re my questions, but I’m still searching for your impression of the ultimate source of energy that pushes the water around, etc. Is it as simple as the rotation of the Earth creating surface/air friction?”
As described above there are multiple phenomenon at work. Gravity is one. The Coriolis effect is another. Convection is another.
Refer to ENSO FAQ webpage by Bill Kessler of NOAA:
http://faculty.washington.edu/kessler/occasionally-asked-questions.html
And the one by David Enfield, also of NOAA:
http://www.aoml.noaa.gov/general/enso_faq/
Keith Minto: You asked, “With the trade winds moving water to the western pacific during La Nina, does the relatively shallow water around Indonesia and Australia/New Guinea form a barrier to this water moving to the Indian Ocean ?”
The landmass forms a barrier that allows the Pacific Warm Pool to form. There is some transfer from the Pacific to the Indian Ocean by a current called the Indonesian Throughflow.
You asked, “Does the Indian Ocean Dipole play a part in this cycle?”
And vice versa. For a place to start, refer to Ashok et al (2001) in that discussion:
http://www.jamstec.go.jp/frcgc/research/d1/iod/grl_ashok.pdf
And refer also to the JPL animation of Sea Level anomalies. Watch for the Rossby wave carrying warm water from east to west in the Indian Ocean during the 1997/98 El Nino, then the blast of elevated sea level in the western tropical Indian Ocean.
There is also a spike in the western tropical Indian Ocean SST anomalies at that time. It appears it also occurs during other major El Nino events:
http://i49.tinypic.com/29uu83m.jpg
jeef says: “Surprised that anyone could think they are opposites to start with.”
But that’s how they are presented:
http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensofaq.shtml#NINACHAR
NOAA writes, “La Nina- related oceanic and atmospheric conditions are generally opposite to those of El Niño.”
And scrolling down to the discussion of the main differences between El Nino and La Nina, NOAA writes, “El Niño and La Niña represent opposite extremes in the naturally occurring climate cycle referred to as the El Niño/Southern Oscillation (ENSO). ”
When in actuality, La Nina is simply an exaggeration of the ENSO-neutral phase, while El Nino includes shifts in locations of warm surface and subsurface waters and convection and the reversal of “normal” trade winds and ocean currents. I often think of La Nina as nature overshooting its goal while it attempts to return to a normal state.
Layman Lurker says: “Detrend global SST anomalies, but you would look for the residuals in the applicable ocean subsets. Would this not confirm the rebuttal of Thompson et al that you are implying?”
Detrending Global SST anomalies and those of the other datasets adds complexity to the discussion. It also doesn’t help to illustrate the differences that much, but it was worth a look. Here’s a graph of detrended global SST anomalies versus detrended and scaled NINO3.4 SST anomalies:
http://i49.tinypic.com/21n34p0.jpg
And East Indian & West Pacific SST anomalies versus detrended and scaled NINO3.4 SST anomalies:
http://i47.tinypic.com/2vabkup.jpg
And East Pacific, Atlantic, & West Indian SST anomalies verus versus detrended and scaled NINO3.4 SST anomalies:
http://i50.tinypic.com/de21vs.jpg
I also looked at subtracting the scaled NINO3.4 SST anomalies from the datasets to show the residuals, but that too added complexity. These topics are complex and confusing as is.
I like the colored graph that shows how the warm waters allowed to develop under El Nino conditions are then pushed to the West and migrate over time to the poles as the wind picks up again. Their trail leaves cooler waters behind. This cycling oscillating chaotic imbalanced system made up of Solar IR, precip, wind (atmospheric pressure differentials), oceanic currents, and topographical boundaries explains much related to land temperatures.
But this is not the only game in town. If this system is on its own chaotic oscillation timing, it stands to reason that other parts of the globe have systems that also work in similar ways and on their own somewhat chaotic oscillating timing. And since the world is not made up of separate contained systems, these systems overlap with each other and even occasionally invade quite deeply into each other. These interactions likely set up the occasional decades long rise or fall in temperatures.