>A Fresh Look at NCDC Absolute Part 3

>Please refer to the notes on data source prior to downloading the JunkScience .csv files.
http://bobtisdale.blogspot.com/2008/05/fresk-look-at-ncdc-absolute-data-source.html

GLOBAL LAND TEMPERATURE

In my view, I saved the best for last.

Figure 3.1 illustrates the large span of annual global Land Surface Temperature (LST) and the significant changes in maximum and minimum values.


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Figure 3.1: NCDC Absolute Global Temperature – Land – Jan 1900 to Mar 2008

Figure 3.2 shows the maximum, minimum, and average readings of each calendar year from 1880 to 2007, with all the interconnecting data removed. The difference between the minimum and maximum values is so great it hides many of the highlights in those variables.

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Figure 3.2: NCDC Absolute Annual Global LST – Maximum, Minimum, Average – 1880 to 2007

The average absolute annual global LST, Figure 3.3, differs little from the standard anomaly representations of LST.

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Figure 3.3: NCDC Absolute Annual Global LST – Average – 1880 to 2007

Like Figure 1.8 in the first part of this series, the curve of the annual minimum LST data, Figure 3.4, is much more linear; that is, the multiple positive and negative trends are much less pronounced, and they may have shifted. Again, using the linear trend as reference, it’s relatively straight from 1890 to 2007, with a dip between 1960 and 1980.


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Figure 3.4: NCDC Absolute Annual Global LST – Minimum – 1880 to 2007

Again, that dip in Annual Minimum Global LST seems to correlate with the 1960 to 1980 drop in TSI associated with Solar Cycle 20. Refer to Figure 3.5.

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Figure 3.5: TSI and Maximum-to Maximum Trends

The Maximum Global LST data holds such a surprise that I first want to illustrate the data from 1880 to 1997. Refer to Figure 3.6a and Figure 3.6b. Nothing out of the ordinary in either graph.


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Figure 3.6a: NCDC Absolute Annual Global LST – Maximum – 1880 to 1997


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Figure 3.6b: NCDC Absolute Annual Global LST – Maximum with Polynomial Trend – 1880 to 1997

Now, let’s add the 1998 through 2007 data. Refer to Figure 3.6c and Figure 3.6d. Look at that step change. I got a little carried away with the red trend lines in Figure 3.6c, but the transition in 1998 is visible in Figure 3.6d. I’ve marked 1997 with a red dot. Based on the linear trend lines, maximum annual global LST jumped approximately 0.6 deg C after the 1997/98 El Nino and stayed there. Hopefully, the current La Nina will draw that back down. Time will tell. Refer also to “Let’s Not Forget The Other Influences” that follows, prior to the closing.

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Figure 3.6c: NCDC Absolute Annual Global LST – Maximum – 1880 to 2007

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Figure 3.6d: NCDC Absolute Annual Global LST – Maximum with Polynomial Trend – 1880 to 2007

The long-term effects of the 1997/98 El Nino are also visible in Figure 3.7.

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Figure 3.7: UAH MSU Temperature Anomalies 12/78 to 2/08 – Global, Northern Hemisphere, North Pole

The difference between global LST annual extremes (maximum minus minimum) decreased over time. Refer to Figure 3.8. This is no surprise.

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Figure 3.8: NCDC Absolute Annual Global LST – Maximum minus Minimum – 1880 to 2007

Unexpected: the greatest rate of change occurred from 1890 to 1920, where minimum temperature rose considerably faster than maximum, and that from 1980 to 2000, the rates of change were almost identical. To create that graph, I shifted both maximum and minimum data until their polynomial trends nearly overlapped in the late part of the 20th Century. Refer to Figure 3.9.


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Figure 3.9: NCDC Absolute Annual Global LST Annual Maximums and Minimums Shifted for Comparison of Polynomial Trends – 1880 to 2007

RETURNING TO THE LONG-TERM EFFECTS OF THE 97/98 EL NINO

Figures 3.10a through 3.10d further illustrate the long-term effects on LST of the 1997/98 El Nino. Figure 3.10a compares average LST of the 10 years before, after, and including 1997/98. Figure 3.10b illustrates the difference in the LST average of those two decades. Since the 1997/98 El Nino years could impact the averages, Figures 3.10c and 3.10d repeat the illustrations with the years 1997 and 98 removed.


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Figure 3.10a: Average Monthly LST of 1988-97 and 1998-07 – Includes El Nino Years of 1997/98
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Figure 3.10b: Difference Between Monthly LST Averages of 1988-97 and 1998-07

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Figure 3.10c: Average Monthly LST of 1988-96 and 1999-07 – Excludes El Nino Years of 1997/98

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Figure 3.10d: Difference Between Monthly LST Averages of 1988-96 and 1999-07

In Figures 3.11a through 11d, I replaced LST with SST to see if there was an oceanic step response to the 97/98 El Nino. It’s there, and if we assume there are no other heat sources for sea surface temperature, big assumption (Refer to “Let’s Not Forget The Other Influences” that follows), it’s on the order of 0.16 deg C.

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Figure 3.11a: Average Monthly SST of 1988-97 and 1998-07 – Includes El Nino Years of 1997/98


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Figure 3.11b: Difference Between Monthly SST Averages of 1988-97 and 1998-07


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Figure 3.11c: Average Monthly SST of 1988-96 and 1999-07 – Excludes El Nino Years of 1997/98


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Figure 3.11d: Difference Between Monthly SST Averages of 1988-96 and 1999-07

LET’S NOT FORGET THE OTHER INFLUENCES
Scaffeta and West in their March 2008 opinion titled “Is Climate Sensitive to Solar Variablility?”, published in “Physics Today”, produced Figure 3.12. This illustrates that more than a 0.1 deg C portion of the rise from 1997 to 2002 could result from solar irradiance. However, solar peaked in 2002, while maximum LST have remained high.

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Figure 3.12: Global Surface Temperature Anomaly and Phenomenological Solar Signatures – ACRIM (Red) vs PMOD (Blue) –Scaffeta and West (2008)
The Atlantic Multidecadal Oscillation rose from the mid-70s to 2005, but it too has been dropping since. The Pacific Decadal Oscillation (PDO) and its basin-wide kin the Interdecadal Pacific Oscillation (IPO) have been decreasing spasmodically since 1997.
In addition to the 1997/98 El Nino, there have also been three El Nino episodes since: 02/03, 04/05, 06/07. These were originally countered by the La Nina episodes 98/99, 99/00, 00/01 prior to the significant La Nina we are presently experiencing.
Regardless, these variables cannot explain that large step change in maximum LST without the 97/98 el Nino.
CLOSING
The preceding three-part evaluation of NCDC Absolute Global Temperature Data exposed relationships and natural effects hidden by anomaly data. I hope, and I’m sure, this will lead to other finds that further detail the major impacts of natural causes of climate change. I’ve limited this investigation to graphics available with my very basic working knowledge of EXCEL. Those with more advanced statistical devices, such as Hodrick-Prescott (HP) filters and filtering processes available through WoodforTrees http://www.woodfortrees.org/ , should be able to prompt more.

About Bob Tisdale

Research interest: the long-term aftereffects of El Niño and La Nina events on global sea surface temperature and ocean heat content. Author of the ebook Who Turned on the Heat? and regular contributor at WattsUpWithThat.
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