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Sunday, June 29, 2008

Combined Solar and Volcanic Aerosol Effect – Part 1

To attempt to properly investigate the possible solar origin of the late 19th to early 20th century plunge in SST, total solar irradiance (TSI) cannot stand alone. The impact of volcanic aerosols must be included. I attempted to find a data set that combined the two and uncovered multiple discrepancies in the GISS radiative forcing data that render that compilation useless to me.


The following quote is from the GISS Surface Temperature Analysis, Global Temperature Trends: 2007 Summation: “This cyclic solar variability yields a climate forcing change of about 0.3 W/m2 between solar maxima and solar minima. (Although solar irradiance of an area perpendicular to the solar beam is about 1366 W/m2, the absorption of solar energy averaged over day and night and the Earth's surface is about 240 W/m2.) Several analyses have extracted empirical global temperature variations of amplitude about 0.1°C associated with the 10-11 year solar cycle, a magnitude consistent with climate model simulations, but this signal is difficult to disentangle from other causes of global temperature change, including unforced chaotic fluctuations.”

In a later graph on that webpage, they illustrate that the 0.3 W/m2 is calculated from min to max of the last two solar cycles.

Figure 1

On another webpage, GISS discusses radiative forcings used in their climate models:
And they list separate radiative forcing data for numerous variables, including solar irradiance and volcanic aerosols.
Figure 2 illustrates the GISS solar radiative forcing. The curve is that of the Lean et al (2000), including background. Their use of the Lean et al data is confirmed in the GISS discussion “Climate simulations for 1880–2003 with GISS modelE”.
The accuracy of this data set was questioned by the author within a year because, in a later paper, she felt it was incorrect, yet GISS continues to use it. The second thing that stands out is the maximum-to-minimum variation in the last two solar cycles. It’s approximately 0.14 watts/meter^2, or less than half that listed in the GISS 2007 Summation of Temperature Trends. Does GISS need the erroneous data set calibrated to less than half of the accepted values in order to give more weight to anthropogenic forcings when they attempt to duplicate the global temperature record with their climate models?

Figure 2

Figure 3 shows the radiative forcing of stratospheric aerosols resulting from explosive volcanic eruptions. It is based on the GISS Sato Index of Mean Optical Thickness, which, from my investigations, appears to be the best volcanic dust veil index available. Unfortunately, the Sato Index data only goes back as far as 1850. In this illustration, GISS presents the data in terms of watts/meter^2 from 1880 to 2003.

Figure 3

The solar and volcanic aerosol data are illustrated together in Figure 4. The magnitude of stratospheric (volcanic) aerosol forcing dwarfs that of solar irradiance. Looking at the Mount Pinatubo eruption of 1992 and the last two solar cycles, the volcanic aerosol radiative forcing is 20 times that of the min-to-max radiative forcing for the last two solar cycles. GISS claims this min-to-max change in solar irradiance is responsible for a 0.1 deg C change in global temperature, as noted above. That would mean, based on the relative magnitude of solar irradiance to stratospheric aerosols, that global temperatures dropped 2.0 deg C in response to the Mount Pinatubo eruption. That didn’t happen. The maximum estimate of the annual drop in temperature from Mount Pinatubo is 0.5 deg C and the minimum is 0.2 deg C.

Figure 4

It’s a shame that GISS has to manipulate data to fit their purposes. If I had the time, I would investigate the other forcings GISS provides in the data set above, but I don’t and I won’t. The GISS data is skewed and worthless for my uses. It may work in the GISS climate models, but it will not work in a comparison to historical temperature record data.


This will be discussed in the second of this series.

Saturday, June 28, 2008

Thermohaline Circulation Upwelling Area SST - Part 1

Figures 1 to 5 are illustrations of Thermohaline Circulation (THC) readily found on the web.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

No two illustrations of THC are exactly the same, indicating the limits of our knowledge of the phenomenon. In fact, looking at Figure 6, (From “Stability of Southern Ocean Thermohaline Circulation”, marsland.ccs.110804.ppt), which illustrates THC subduction and upwelling points, very few of the upwelling areas agree with those shown in Figures 1, 2, 4 and 5.
Figure 6

Regardless, based on the upwelling areas in Figure 6, their coordinates were identified. Refer to Figure 7. The areas are coded with the same colors as the following graphs. The eastern equatorial Pacific has already been examined in this series, so it has been excluded from this post. Note: In a future post, I will look at the “mixing-driven” upwelling points identified in Figure 5.
Figure 7

Figures 8 and 9 show the SST and SST anomalies for four of the upwelling areas. Not shown is the area in the Southern Ocean, which would have skewed the SST graph. The SSTs (smoothed with an 85-month filter) vary from approximately 14 to 22 degrees C.
Figure 8

Figure 9

Figure 10: The areas off the U.S. West Coast (blue) and the Southwest Coast of Africa (purple), a hemisphere and an ocean away, have the same significant dip in temperature from the late 19th to the early 20th centuries. There is an approximate 5- to 6-year difference between their declines.
Figure 10

The upwelling areas off the South American West Coast (red) and the African Northwest Coast (green) have declines near the same period that are more rounded. Refer to Figure 11. In those areas, whatever caused the drops has either been muted with respect to the other two anomalies (Figure 10) or they are initiated by something entirely different or something on a different time scale.
Figure 11

The outlier is, of course, the SST of the Southern Ocean upwelling area, Figure 12. Its curve bears no resemblance to the others. Smoothed with an 85-month filter, its SST curve varies little from its SST anomaly curve, so I’ve used SST.
Figure 12


Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

Friday, June 27, 2008

El Nino Effects on Global Equatorial SST

The original intent of this post was to illustrate the time lags from the East Equatorial Pacific (NINO3 plus most of NINO4) to the West Equatorial Pacific (Pacific Warm Pool), the Indian Ocean, and the Atlantic Ocean, but the absence of an expected rise in the West Pacific reminded me of the origin of an El Nino’s heat: The Pacific Warm Pool.

Prior to reading the rest of this post, please watch a 2.5 minute film from the NASA Scientific Visualization Studio titled “Visualizing El Nino”. http://svs.gsfc.nasa.gov/vis/a000000/a000200/a000287/a000287.mpg
Source: http://svs.gsfc.nasa.gov/vis/a000000/a000200/a000287/index.html

It has great graphics and provides informative explanations of the processes of the 97/98 El Nino.

Figure 1 illustrates the Equatorial SST Anomalies in the Atlantic, Indian, and East and West Pacific Oceans, from January 1996 to December 2000, catching the impacts of the 97/98 El Nino. The monumental spike in the East Pacific SST anomaly is the stand-out feature. Notice, however, that initially, from February to March 1997, both the Indian and East Pacific Oceans rise in unison, after which time the Pacific skyrockets and the Indian Ocean climbs much more subtly. After the East Pacific and Indian Ocean anomalies rise above zero in March 1997, the Atlantic responds with its increase in temperature. This initial Atlantic temperature increase appears, based on timing, as if it would have to be the reaction to increased atmospheric temperatures, and the later jump in Atlantic SST in mid-1999 (21 months later peak-to-peak) would most likely be an oceanic response, where the wave of elevated SST finally made it to the equatorial Atlantic.

Figure 1

Much more subtle, and the reason for asking that you watch the video, is the interaction between the Equatorial West and East Pacific. The West Pacific temperature anomaly decreases as the East Pacific increases. Then, around July or August 1998, the West Pacific anomaly begins to rise slowly. It continues to increase at that snail’s pace until the East anomaly drops below the West; then the West increases much more quickly. From that point on, it appears the two areas of the equatorial Pacific are transferring heat back and forth, with a small change in the West Pacific causing an amplified change in the East.

Monthly SSTs for the same period and variables are illustrated in Figure 2. Looking at the East Pacific curve, the not only did the 97/98 El Nino elevate the summer peaks, it also eliminated the winter trough.

Figure 2

In Figure 3, the SST anomalies for the 82/83 El Nino for the same areas of the equatorial oceans are illustrated. The reactions of the East and West Pacific are significantly different, due in part, at least, from the explosive volcanic eruption of El Chichon. The secondary 21-month response lag of the Atlantic is the same as in the 97/98 El Nino. Based solely on the reaction of the Atlantic following both major El Ninos, there appears to be a consistent 21-month lag in Atlantic SST to a change in the East Pacific.

Figure 3

Figure 4 shows the SSTs for the 82/83 El Nino.

Figure 4

In the last two graphs, Figures 5 and 6, the 06/07 El Nino and 07/08 La Nina effects on equatorial SSTs are illustrated. What I find most interesting about this graph is the fall in West Pacific SST since January 2007, most visible in Figure 5. If the West Pacific Warm Pool supplies the energy for El Ninos, the heat source is dwindling.

Figure 5

Figure 6


Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

Thursday, June 26, 2008

The Common Misunderstanding about the PDO

CORRECTION: In agreement with my post The Atlantic Multidecadal Oscillation - Correcting My Mistake, I have replaced this post, correcting the description of how the AMO is calculated. Refer to the replacement post Misunderstandings about the PDO – REVISED for an expanded discussion on the Pacific Decadal Oscillation.

Wednesday, June 25, 2008

Solar Signal in East Equatorial Pacific SST?

In a prior post “Equatorial SST Comparison”, the Eastern Equatorial Pacific (5S to 5N by 80 to 180W) displayed an oscillation that appeared to have an 11-year cycle, a solar signature. Refer to Figure 1, which has been smoothed with an 85-month filter.
Figure 1

Unfortunately, I haven’t found a TSI reconstruction with monthly data, but the SST anomaly data is monthly, so sunspots will have to do in the initial comparison. Figure 2 illustrates raw and smoothed monthly sunspot data. Note that the smoothing gives the sunspot minimums a curve.
Figure 2

In Figure 3, the two data sets, Eastern Equatorial Pacific SST Anomaly and Scaled TSI, are compared. I’ve highlighted peaks in the two curves that indicate there may be a correlation if the TSI data set was shifted. This would infer a 30-year+ lag in Eastern Equatorial Pacific to changes in solar irradiance, which could be possible because the Eastern Equatorial Pacific is considered an upwelling point of thermohaline circulation. So let’s shift the TSI data.
Figure 3

Figure 4 compares the TSI and Eastern Equatorial Pacific SST Anomaly data sets, with the TSI data shifted 33 years. Considering the amount of noise in the raw SST data and the time span between the two data sets, that’s not a bad correlation. If this lag is correct, the small area of the Pacific Ocean is reacting today to changes in TSI that occurred in 1975.
Figure 4

There will be those who believe the smoothing creates the appearance of a correlation, when, if fact, none exists. Figure 5 illustrates the raw TSI and East Equatorial Pacific SST anomaly data. Is the correlation still visible in it?
Figure 5

To compare against TSI, which does have a different basic curve than sunspots, the other alternative is to annualize the SST anomaly data. Refer to Figure 6. The correlation still exists, but the scaling factor used indicates an SST sensitivity much greater than accepted climate sensitivities. Is this a problem? Possibly not, if the surface area of the thermohaline circulation upwelling points is compared to the total oceanic surface area. If these upwelling areas of relatively small area are dissipating the variations in total stored heat of deep water, the signals should be amplified above what would be considered normal for sea surface sensitivity.
Figure 6


Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

Equatorial SST Comparison

Figure 1 is a global Mercator projection that shows how the data sets were divided in the following comparison. The primary reason for the illustration is to show where I split the Indian and Pacific Oceans.

Figure 1

Figures 2 and 3 illustrate equatorial SST anomaly and SST data for the Atlantic (Blue), Indian (Green), and Pacific (Red) Oceans from January 1854 to May 2008. All three data sets were smoothed with an 85-month running average filter. In Figure 2, the Pacific Ocean anomaly has greater year-to-year perturbations, as expected, primarily a result of ENSO, while the overall trend of the Indian Ocean varies more than the other two oceans. I would’ve expected the Atlantic to be the ocean with the greatest variation at the equator since the Indian Ocean is so rarely discussed in papers, but that could just be the way I select reading material. The SSTs illustrated in Figure 3 didn’t come as a surprise, considering the differences in hemispheric ocean areas.
Figure 2

Figure 3

The problem with illustrating the Equatorial Pacific as one data set is that it fails to account for the significant differences between the East and West. The Western Equatorial Pacific is part of the Pacific Warm Pool, which registers the highest ocean temperatures. The Eastern Equatorial Pacific is well known for its El Nino/La Nina activity, but it is also one of the global ocean areas of upwelling of cool subsurface waters. In Figures 4 and 5, I’ve divided the Pacific into two data sets, East (Bronze) and West (Purple) of 180 deg longitude. I’ve left the Indian and Atlantic Oceans as references. Figure 4 shows that the Western Equatorial Pacific is placid, its yearly variations and overall trends varying comparatively little, while in the Eastern equatorial Pacific, changes in trends are as large as the Indian and Atlantic Oceans and its annual variations dwarf the others. Recall that those data sets have been smoothed with 7-year+ filters. In Figure 5, the middle-of-the-road Pacific SSTs from Figure 3 are now the two extremes. The Western Equatorial Pacific is approximately 3 deg C warmer than the Eastern. What really stand out to me in the Eastern Equatorial Pacific (Bronze) curve are the 11-year (approx) jaggedly topped cycles, but then I’m always looking for solar influences. I’ll have to do a comparison with solar in another post.
Figure 4

Figure 5

In Figures 6, 7, and 8, the time span of the data has been shortened to the last 30 years and the smoothing has been eliminated. The size of the annual changes in SST and SST anomaly of the Eastern Equatorial Pacific makes the temperature scale of the data so large that the changes in the other data sets become insignificant. Figure 6: It’s barely possible to make out the lags in the responses of the other oceans to the major ENSO events in the Eastern Equatorial Pacific. After the clearly identifiable 82/83 and 97/98 El Nino peaks in the Eastern Pacific data, the Equatorial Atlantic portrays a small spike 21 months later. The timing is consistent in both instances. In Figure 7, the vertical bronze lines mark the peaks of the two major El Ninos. The lags in the Indian, Atlantic, and Western Pacific Oceans to the 82/83 and 97/98 El Nino events are much clearer when the Eastern Pacific data is removed from the graph. What are also quite clear are the magnitudes of the drops in temperature that have recently occurred in the equatorial segments of the Indian and Western Pacific Oceans. Will they continue to decline now that the La Nina, visible in the Eastern Pacific data of figure 6, has started to rise, or will they follow? Their histories indicate that they should follow. The lowest Eastern Equatorial Pacific anomaly of the recent La Nina was reached in November 2007. Will the Equatorial Atlantic respond 21 months later, in August 2009?

Looking again at Figure 7, the rises in the Atlantic, Indian, and Western Pacific data after 2000 appear to be an aftereffect of the 97/98 El Nino. Could it have taken 10 years to dissipate the heat discharged into the surface of the world oceans by that one El Nino? There were reports in 1994 that the oceanic Rossby waves generated by the 82/83 El Nino were still visible after 12 years. The upwardly bowed responses in temperature from 2000 to 2008 are most evident in the annual minimums of the Equatorial Eastern Pacific, Indian, and Atlantic data sets in Figure 8. And look at the period of the oscillation in the annual minimum temperature of the Eastern Equatorial Pacific data. While there’s only 30 years of data, those look like 10 to 11 year cycles. I’ll look at it in another post.

Figure 6

Figure 7

Figure 8


Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

Sunday, June 22, 2008

The Atlantic Ocean

No series of SST blog posts would be complete without a view of the Atlantic Ocean SST and Anomaly data. Refer to Figure 1, which illustrates Northern and Southern Hemisphere SST anomalies for the Atlantic, from January 1854 to May 2008, both data sets smoothed with a 37-month filter. The North Atlantic displays the well-documented cycles associated with thermohaline circulation. In the South Atlantic, that cycle is visible, but it’s been suppressed significantly by time and mass. The South is also impacted by other influences that give it the spikes that peak around 1940 and 1975. The Northern SST anomaly curve appears to have topped out recently, possibly heralding a downturn in the AMO. The Southern anomaly has been relatively flat for almost 20 years.

Figure 1

In Figure 2, I’ve shortened the time span to from January 1979 to present. The data has not been smoothed. The South Atlantic appears to be on a slow downward trend that started 10 to 12 years ago. The North Atlantic might be declining, though it’s tough to tell with data that noisy.

Figure 2

For reference, I’m providing a glimpse at monthly SST data for the North and South Atlantic, from January 1979 to present, in Figure 3.

Figure 3


Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

Smith and Reynolds SST Posts

UPDATE 3-28-09: As you will note, I stopped logging the SST posts on this thread back in December 2008. I have, however, continued to write posts on SST, sometimes using Hadley Centre data, sometimes using the NCDC's OI.v2 data.

Please also use the search feature in the extreme upper left-hand corner of this webpage to find what you're looking for.

OPENING NOTE: These posts are about sea surface temperature (SST), not about AGW.


NOMADS, NOAA’s National Operational Model Archive and Distribution System, allowed (past tense) users to download data from and create graphs of the Smith and Reynolds ERSST.v2 dataset. The ERSST.v2 data is no longer being updated. It has been replaced by ERSST.v3b data, which is not yet available through NOMADS, so the NOMADS links have been removed.

ERSST.v2 data can still be downloaded from the KNMI Climate Explorer website:


AMO Versus Mid-Latitude North Pacific Residual

SST By Latitude

My Only Complaint About ERSST Data on NOMADS

Calculating Basin-Wide Pacific SST

Multiple North Pacific Decadal and Multidecadal Oscillations

Global SST Anomaly Comparison

Arctic SST

The Antarctic Peninsula

The Unusual Temperature Rise Around 1940

Unusual SST Anomaly 1 – South of the Cape of Good Hope

Looking for the Source of ENSO

Update 1 - June 22, 2008

The Atlantic Ocean

Update 2 – June 25, 2008

Equatorial SST Comparison

Solar Signal in East Equatorial Pacific?

Update 3 – June 27, 2008

El Nino Effects on Equatorial SST

The Common Misunderstanding About the PDO

Update 4 - June 28, 2008

Thermohaline Circulation Upwelling Area SST – Part 1

Update 5 - July 14, 2008

Ocean Areas in IPCC TAR Figure 2.9(c) That Cooled From 1946 to 1975

Update 6 – July 19, 2008

Preliminary Post - Mid-Latitude South Pacific SST and SST Anomalies Segmented by 10 Degrees Longitude

Preliminary Post - Mid-Latitude North Pacific SST and SST Anomalies Segmented by 10 Degrees Longitude

Update 7 - July 24, 2008

Southern Ocean

Update 8 - July 25,2008

Ocean Areas in IPCC TAR Figure 2.9(c) That Warmed From 1946 to 1975 – Part 2 of a 2-Part Series

Update 9 - July 26, 2008

SSTs at the Centers of Ocean Gyres and A Predictor (?) of North Atlantic SST

Update 10 – August 9, 2008

Indian Ocean and South Atlantic Ocean

Update 12 - August 14, 2008

The Barents and Bering Seas

Update 13 – August 16, 2008

30+ Years of Ocean SSTs - January 1978 to July 2008

Update 14 – August 19, 2008

Tropical Atlantic, Indian, and Pacific Ocean SSTs

Update 15 - August 28, 2008

NINO3.4 SST (Not Anomaly) - Part 1

NINO3.4 SST (Not Anomaly) - Part 2

NINO3.4 SST (Not Anomaly) - Part 3

Update 16 – September 1, 2008

ERSST.v3 Version of Southern Ocean SST Anomaly

Update 17

August 2008 SST and SOI Updates

Update 18

Tropical SST Anomalies Revisited – Introduction

Tropical SST Anomalies Revisited – Atlantic Ocean

Update 19 – October 2, 2008

Tropical SST Anomalies Revisited – West Pacific Ocean

Update 20 (I’ve been a little lax in keeping this up to date. Sorry.)

ERSST.v3 Version of Arctic Ocean SST Anomaly

Peruvian Coast SST Anomalies

Tropical SST Anomalies Revisited – Indian Ocean

The Pacific Warm Pool versus ENSO

September SOI and SST Update

Update 21 – October 22, 2008

Atlantic, Indian, and Pacific Ocean SSTs Segmented By Longitude

Update 22 – October 26, 2008

The 1976 Pacific Climate Shift

Update 23 – October 29, 2008

Atlantic and Pacific SST Dipoles

Update 24 - November 6, 2008

Another Look at the Saw-Tooth Trends in the Indian Ocean

A Different Way to Look at NINO3.4 Data

Update 25 – November 20, 2008

Average Subsurface Temperature of the Equatorial Pacific

Equatorial Pacific Warm Water Volume

NINO3.4 & Warm Water Volume & Subsurface Temperature

October 2008 SST Update

Optimally Interpolated SST (OI.v2 SST) versus Extended Reconstruction ERSST.v2) Data

NINO3.4 Data Comparison – HADSST and ERSST.v2

UPDATE 26 – DECEMBER 6, 2008

Atlantic Meridional Overturning Circulation Data

An Interesting Correlation With North Atlantic Subpolar Gyre SST

Dip and Rebound

Recharging The Pacific Warm Pool

Why Does GISS Use HADSST2 Data From 1880 to 1981?


Multiple North Pacific Decadal and Multidecadal Oscillations

Figure 1 illustrates the Global and Mid-Latitude North Pacific SST Anomalies from January 1854 to May 2008. The data have been smoothed with a 37-month running-average filter, comparable to a 3-year filter. In Figure 2, the residual of those two curves (Mid-Latitude North Pacific SST Anomaly MINUS Global SST Anomaly) is shown. I had never seen curves like these illustrated before and I was sure I had made a mistake, in data selection while downloading, in merging East and West Pacific data sets. I repeated the process and came up with the same result.

Figure 1

Figure 2

How else could I verify the North Pacific had those curves? I picked four areas in the North Pacific, illustrated in Figure 3 and graphed the data from them.

Figure 3

The coordinates for the North Pacific data sets are:
Northwest = 40 to 50N, 150 to 160E
Northeast = 40 to 50N, 130 to 140W
East Central = 15 to 25N, 150 to 160W
West Central = 15 to 25N, 160 to 170E

Figure 4 illustrates the SST anomaly data for those four regions, all smoothed with 85-month filters. (With areas that small, a 3-year filter still leaves too much noise.) Based on the general shapes of the four curves, I concluded I had not made a mistake with the earlier data and graphs.

The second thing that stood out in Figure 4 was the significant drop in SST between 1900 and 1930. Next were the lag times between the temperature drops, and the different recoveries. The fourth thing I noted was that the amplitude and frequency of the oscillations in North Pacific temperature varied per region, but they too were decadal to multidecadal in nature. The North Pacific is teaming with decadal and multidecadal temperature oscillations that vary in amplitude and frequency.

Figure 4

The SST temperature anomaly curve for the North Pacific (south of 65N) was added in Figure 5. I elected not to use Mid-Latitude North Pacific data (Figure 1), since the two lower latitude data sets used in the comparison were outside that area. While the influence of the regions is apparent, there are obviously other areas, the equatorial Pacific and the Arctic, that impact the regional and hemispheric North Pacific data.

Figure 5

Did late 19th and early 20th century volcanic aerosols cause the drop in North Pacific SST? Refer to Figure 6. In it I added a very much scaled SATO index of optical thickness for reference. Based on the lack of a similar response in the latter half of the 20th century to volcanic eruptionsof comparable size, and based on the time lags for the central Pacific data sets to react to the drop in temperature, I’d have to say that it wasn’t volcanic aerosols. What else? Thermohaline circulation? The North Pacific, in some reports, is an area of upwelling of subsurface water.

Figure 6


Bloggers constantly proclaim “The PDO has flipped”, or “switched,” and forecast its influence on global temperatures, without understanding that the PDO is statistical function of North Pacific SST. It is not North Pacific SST. The PDO explains regional climate variations. There is also a coincidence between the phase of the PDO and the sign, frequency, and magnitude of ENSO events. As discussed in numerous papers, ENSO events drive the PDO. ENSO events do not, however, drive the oscillations illustrated in this post.


Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

Saturday, June 21, 2008

Looking for the Source of ENSO

August 14,2009 Update: This is an early post in my SST research. I had made some assumptions in it that I do not agree with now, but I've elected not to delete the post because it illustrates some interesting correlations. I have, however, deleted the opening paragraph, a few of the final paragraphs, and the last two illustrations.

I would title the post differently now, too.


Figure 1 is a graph of the mid-latitude South Pacific SST anomaly, smoothed with an 85-month filter. Due to the sheer size of the South Pacific, and the filtering, the 82/83 and 97/98 El Nino events appear as tiny bumps on the curve.

Figure 1

Dividing the basin into smaller segments (Figure 2) and graphing those areas will hopefully provide a clue. The area highlighted in blue in Figure 2 is actually a part of the South Indian Ocean.

Figure 2

The segmented mid-latitude South Pacific SST anomalies are illustrated as a spaghetti graph in Figure 3, where the data is color coded with the areas highlighted in Figure 2.

Figure 3

Many of the SST anomaly curves follow a general pattern illustrated in the basin-wide graph. Refer to Figures 4 and 5, which cover the western and central South Pacific.

Figure 4

Figure 5

Then there is the outlier. In Figure 6, the SST anomaly for the area adjacent to South America is illustrated in black. Note the four major rises in temperature, peaking in 1879, 1897, 1940, 1779-81, and 1995. Recall that this graph is smoothed with a 7-year+ filter. I wonder if predictions of major El Nino events could come from major rises in Eastern Pacific SST.

Figure 6

But what about the overall shape of the eastern mid-latitude South Pacific SST anomaly? Comparing it to the filtered Southern Ocean SST anomaly, Figure 7, there is a very basic similarity, very basic. But could the differences be the result of the areas involved (the Southern Ocean is larger in area and its data would, therefore, be dampened) and the result of the freezing temperature of sea water, which would limit the extent of the negative anomalies.

Figure 7

Figure 8 represents the same SST anomalies (Southern Ocean and Eastern Mid-Latitude South Pacific), without smoothing. The Eastern Mid-Latitude South Pacific SST anomaly data has been scaled by a factor of 0.4. The similarities between the two data sets become more apparent.

Figure 8

A very much smoothed ENSO signal (NINO3.4 anomaly) is compared to Eastern Mid-Latitude South Pacific SST anomaly in Figure 9. As expected, the peaks and troughs are correlated, though the overall shapes of the curves vary. Are NINO3.4 temperature trends limited by the opposing Northern and Southern Hemisphere equatorial currents?

Figure 9

Figure 10 again compares NINO3.4 SST and Eastern Mid-Latitude South Pacific SST anomalies, this time unsmoothed. Neither data set has been scaled. You’ll definitely need the TinyPic link to view that graph. Again, they correlate well--not perfectly, but well.

Figure 10

The last graph, Figure 11, compares Southern Ocean SST and NINO3.4 SST anomalies. Detailed comparisons of the Southern Ocean with other data sets are impeded by the data availability for the Southern Ocean. But in general, it’s not a bad correlation.

Figure 11


I did try to carry the comparisons one step farther, by comparing a portion of the Southern Ocean SST anomalies, those west of the Antarctic Peninsula, with the SST anomalies of the Eastern Mid-Latitude Southern Pacific. Unfortunately, the two anomaly data sets turned out to be identical. (SSTs were different; SST anomalies were the same.) Subtracting one anomaly set from the other resulted in a zero difference, exactly, over the entire term of the data. This indicates, at least to me, that the Southern Ocean data for that region are a calculated function of the South Pacific, due to the limitations of available SST data for the Southern Ocean. When describing their newer SST data set, ERSST.v3, Smith and Reynolds mention that the newer data employs satellite data in later years to help with the Southern Ocean calculations. It’s unfortunate; it would’ve been interesting to carry the data comparisons one more step.


Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).


Tips are now being accepted.

Comment Policy, SST Posts, and Notes

Comments that are political in nature or that have nothing to do with the post will be deleted.
The Smith and Reynolds SST Posts DOES NOT LIST ALL SST POSTS. I stopped using ERSST.v2 data for SST when NOAA deleted it from NOMADS early in 2009.

Please use the search feature in the upper left-hand corner of the page for posts on specific subjects.
NOTE: I’ve discovered that some of the links to older posts provide blank pages. While it’s possible to access that post by scrolling through the history, that’s time consuming. There’s a quick fix for the problem, so if you run into an absent post, please advise me. Thanks.
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