September 2008 SST and SOI Update

CORRECTION

In the opening paragraph of this post, I make the following statement: “The newsworthy item this month is the change in the direction of the NINO3.4 SST anomaly data. It’s a minor drop, but it has dropped. IF, big if, it continues to chase the SOI, which it historically tends to do, it has a few more months of decline ahead of it.”

The NINO3.4 SST anomaly does NOT always follow the SOI, though it has been doing so for the past few months. They do correlate remarkably well, but there are times when the changes in NINO3.4 will precede the SOI and times when they can become slightly out of synch. Therefore, I’ll retract the clause “which it historically tends to do”. The sentence should then read, “IF, big if, it (NINO3.4) continues to chase the SOI, it has a few more months of decline ahead of it.”

#

All graphs are from January 1978 to September 2008.

The newsworthy item this month is the change in the direction of the NINO3.4 SST anomaly data. It’s a minor drop, but it has dropped. IF, big if, it continues to chase the SOI, which it historically tends to do, it has a few more months of decline ahead of it. Will the SOI remain there, or fall, or rise more into La Nina territory? (Remember that the SOI and NINO region SST are reversed.) Time will tell.

http://i35.tinypic.com/15ffxbt.jpg
NINO3.4 SST Anomaly
Monthly Change = -0.238 deg C

http://i37.tinypic.com/2agt25c.jpg
SOI
Monthly Change = +5

http://i33.tinypic.com/5txqmb.jpg
Inverted SOI
Monthly Change = -5

http://i34.tinypic.com/2l95wev.jpg
Global
Monthly Change = +0.002 deg C

http://i37.tinypic.com/1sjlh2.jpg
Northern Hemisphere
Monthly Change = +0.026 deg C

http://i38.tinypic.com/6iuycm.jpg
Southern Hemisphere
Monthly Change = -0.016 deg C

http://i33.tinypic.com/2e3rjtu.jpg
North Atlantic (0 to 75N, 70W to 10E)
Monthly Change = -0.013 deg C

http://i37.tinypic.com/j6tvnp.jpg
South Atlantic (0 to 60S, 70W to 20E)
Monthly Change = -0.096 deg C

http://i34.tinypic.com/2v19ljc.jpg
North Pacific (0 to 65N, 90 to 180W) & (0 to 65N, 100 to 180E)
Monthly Change = -0.199 deg C

http://i37.tinypic.com/15wlcgh.jpg
South Pacific (0 to 60S, 70 to 180W) & (0 to 60S, 145 to 180E)
Monthly Change = -0.254 deg C

http://i35.tinypic.com/333bg4z.jpg
Indian Ocean (30N to 60S, 20 to 145E)
Monthly Change = +0.122 deg C

http://i36.tinypic.com/2vkeofd.jpg
Arctic Ocean (65 to 90N)
Monthly Change = +0.03 deg C

http://i38.tinypic.com/ofamvb.jpg
Southern Ocean (60 to 90S)
Monthly Change = +0.009 deg C

SOURCE

Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).
http://nomads.ncdc.noaa.gov/#climatencdc

Fun With Sunspot Numbers

INTRODUCTION

Every now and then I’ll find some phrase or comparison in a blog post or comment or a climate research paper that initiates a new search for a correlation or causal relationship between solar irradiance and ENSO. While I did not expect to find a blatantly obvious ENSO-like signal in a new way of looking at the solar cycle, it didn’t hurt to plot some curves when I had a new idea. Unfortunately, there were no magical hidden solar cycle curves that correlated with ENSO, but what I found did prove to be interesting and might turn out to be of value to someone else.

The latter graphs in this post come from a thought (It was my thought. I won’t blame anyone else.) that had to do with the possible effects of rapid changes in solar irradiance that occur during the ramp up and ramp down phases of the solar cycles. Were there significant differences in solar irradiance from solstice to solstice or from equinox to equinox, above and beyond the annual orbital and angle of incidence variations? The answer is yes. What type of effect this would have on the differences between Northern and Southern Hemisphere ocean heat content or SST, I cannot say. Also, I wouldn’t want to start to think of a process that would make this additional difference turn into a cause or initiator of ENSO, but I found the differences significant enough to post them.

There are no long-term monthly TSI data sets available online—or—I simply haven’t found them yet. However, since this is just a preliminary look, the use of sunspot numbers as a proxy for TSI should not be a problem.

DIFFERENT VIEWS OF SUNSPOT NUMBERS

The typical graph of sunspot numbers, Figure 1, illustrates the 11-year solar cycle. This graph covers the period of 1850 to 2007.

http://i34.tinypic.com/10wmu8m.jpg
Figure 1

For a different view of the variations, in prior posts, I’ve also shown the monthly change (Example: Feb 1850 Minus Jan 1850, etc.) in sunspot number. Refer to Figure 2.
http://i38.tinypic.com/30253qd.jpg
Figure 2

In Figures 3 through 5, I’ve shown the sunspot numbers for each month over the period of 1850 to 2007. Since the name of the solar phenomenon, 11-year solar cycle, reflects an average number, not the true frequency of the cycles, which vary from 9 to 14 years, there are differences in the monthly curves. The only reason I plotted these data sets was to show that there are differences and that the impacts of solar irradiance will vary from year to year (and I had the data divided into months in the spreadsheet).
http://i34.tinypic.com/5fj7mf.jpg
Figure 3

http://i33.tinypic.com/hwmi3n.jpg
Figure 4

http://i35.tinypic.com/5pevk8.jpg
Figure 5

Note: I’ve highlighted the scale of the October sunspot graph in Figure 5 to show that it was different from the other eleven graphs.

And in Figure 6, I’ve illustrated the sunspot numbers for seasons over the period of 1850 to 2007. There are seasonal variations.

http://i35.tinypic.com/303bpn6.jpg
Figure 6

SEASONAL DIFFERENCES IN SUNSPOT NUMBERS

The differences in the average of the monthly sunspot numbers between Winter and Summer and between Spring and Autumn are illustrated in Figures 7 and 8.
http://i33.tinypic.com/105qotu.jpg
Figure 7

http://i38.tinypic.com/1zd5b4p.jpg
Figure 8

DIFFERENCES BEWEEN SOLSTICES AND EQUINOXES

Figure 9 illustrates the annual difference between the December and June monthly sunspot numbers from 1850 to 2007, using the values during those months as an approximation of the values at the solstices. As noted earlier, there can be significant changes in six months, which implies another difference in the amount of solar irradiance delivered to Northern and Southern Hemispheres over the course of a year.
http://i37.tinypic.com/2h3wu48.jpg
Figure 9

In Figure 10, the annual differences in sunspot number between equinoxes are illustrated, using the monthly sunspot numbers in March and September to approximate the values.
http://i34.tinypic.com/1zvz9j6.jpg
Figure 10

SOURCE

Monthly long-term sunspot data is available from the Solar Physics Group at NASA's Marshall Space Flight Center:
http://solarscience.msfc.nasa.gov/
Specifically, this page:
http://solarscience.msfc.nasa.gov/greenwch/spot_num.txt

The Pacific Warm Pool vs ENSO

INTRODUCTION

The following discussion was contained in my recent post about the Tropical West Pacific.
http://bobtisdale.blogspot.com/2008/10/tropical-sst-anomalies-revisited-west.html

I felt it important enough to warrant a post of its own. I have not changed the numbering of the figures, which is why the illustrations begin with Figure 11.

THE RELATIONSHIP BETWEEN EAST AND WEST TROPICAL PACIFIC – THE PACIFIC WARM POOL AND ENSO

The Pacific Warm Pool (PWP) is defined as the area in the Western Tropical Pacific enclosed by the 28.5 deg C isotherm. Refer to Figure 11. I’ve also provided a link to a Quicktime video that shows the modulation in PWP size from 1950 to 2001. Its carry over into the Indian Ocean explains why it’s also known as the Indo-Pacific Warm Pool.

http://i33.tinypic.com/24xf0cw.jpg
Figure 11

Link to PWP Quicktime movie:
http://www.crces.org/presentations/dmv_ipwp/images/SST_WP.MOV

Since the definition of the PWP is area based, most graphs of the PWP illustrate just that, area. Refer to the upper graphs in Figure 12. Others show the warmest annual SST in the Warm Pool, the lower graphs in Figure 12, not annual mean or average. The choice of variables use to illustrate the PWP does little to help expose the relationship between ENSO and the PWP.
http://i35.tinypic.com/34q1z4m.jpg
Figure 12

I had originally intended to show that relationship between the Western and Eastern Tropical Pacific using the NINO3 and NINO6 and the NINO 4 and NINO5 areas--yes, there are NINO5 and NINO6 areas--but comparison graphs of the Western and Eastern Tropical Pacific SST anomalies illustrate the phenomenon better.

But first: Figure 13 shows the currents for the Pacific Ocean. Keys to this discussion are the North and South Equatorial Currents, which travel East to West, and the Equatorial Counter Current, which opposes the North and South Equatorial Currents, running between them and travelling from West to East.
http://i38.tinypic.com/312z0wp.jpg
Figure 13

Most discussions of the PWP use trade winds to explain why warm waters pool in the Western Tropical Pacific. Occasionally, a change in Pacific trade winds causes the collection of warm PWP waters to shift, following a Kelvin wave, and travel east. The subsurface warm waters in the PWP are also shifted to the East and are upwelled in El Nino events. This is explained and illustrated (much better than I can) in the following 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
That video shows the heat moving in only one direction, from West to East; it doesn’t show how the surface waters cycle the heat back and forth between El Nino and La Nina events. That is illustrated in Figures 14 and 15. The short-tem data for east and west data of the North Tropical Pacific (Figure 14) and South Tropical Pacific (Figure 15) have not been smoothed. They also have not been scaled, which may or may not have provided a better illustration of the effect. Note how, in both graphs, the West and East portions of the North and South Tropical Pacific are out of phase. Keying off the El Nino and La Nina events in the Eastern Pacific data, the SST in the East rises when the SST in the west drops. The east responds at a much greater amplitude during ENSO events, but between those events, the amplitudes of the out-of-phase changes can be comparable in magnitude. This is very clear in Figure 14, during the period that extends from mid-1991 to mid-1995. The 1997/98 of course may also provide an exception to the out-of-phase relationship. Refer to the Southern Tropical data, Figure 15. Note how, after the 97/98 El Nino, both data sets decrease in 1998 and 1999 and then, afterwards, begin to vary in opposition. http://i34.tinypic.com/r715j6.jpg
Figure 14
http://i36.tinypic.com/2du9htj.jpg
Figure 15

SOURCES

Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS).
http://nomads.ncdc.noaa.gov/#climatencdc

Figures 11 and 12 and the Quicktime movie are available from the Center for Research on the Changing Earth System (CRCES) at:
http://www.crces.org/presentations/dmv_ipwp/
The map of Pacific Ocean currents was cropped from an image with the title “Ocean currents 1943 (borderless).png” found here:
http://commons.wikimedia.org/wiki/Image:Ocean_currents_1943_(borderless).png