Global warming deniers lose another one.
-.-. --.- Roger
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New Data Show Solar Irradiance Fell Over The Last Three Decades
By Roger Coppock 10/07
ABSTRACT:
An analysis of newly available satellite Solar irradiance
measurements from 1976 to 2007 show a small but significant
decrease of -0.0056 +- 0.0005 Watts per square meter per
year over the 31-year period. Prior releases of data from
PMODWRC showed no significant long term trend in Solar
energy output, only the 11-year solar cycle.
PROCEDURE:
The location of the data's end points within the 11-year
Solar cycle biases a simple linear regression and produces
an incorrect result. (Twice the correct magnitude, or
-0.0099 +- 0.0006 W/m^2 per year.) Therefore, the analysis
required a non-linear curve fit to a 'line plus sine'
expression:
B1 + B2*Year + B3*SIN(B4+(Year*2Pi)/B5)
where the determined coefficients B1, B2, B3, B4, and B5
are known as the intercept, slope, amplitude, phase, and
period respectively.
After correcting for the appropriate cycle of the SIN()
function, (B3>0.0 and 2*Pi>B4>=0.0), the results of the
10485-point curve fit are as follows:
Irad ~ beta1 + beta2 * Year +
beta3 * sin(beta4 + (Year * 2*Pi)/beta5)
Parameters:
Estimate Std. Error t value Pr(>|t|)
beta1 1.37721e+03 9.82683e-01 1401.48263 < 2e-16
beta2 -5.64843e-03 4.93169e-04 -11.45333 < 2e-16
beta3 4.93317e-01 5.95419e-03 82.85200 < 2e-16
beta4 1.82549e+00 2.91597e+00 0.62603 0.53131
beta5 1.00574e+01 2.35641e-02 426.81086 < 2e-16
Residual standard error: 0.434 on 10480 degrees of freedom
Please see:
http://members.cox.net/rcoppock/Solrad.jpg
The data are black. The linear component, both intercept
and slope, is green. The total 'line plus sine' function
is red.
The curve fit was performed by the "R" statistical package
for Power PC OSX, Version 2.2.1.
The dual cavity radiometer Solar irradiance data come from
PMODWRC. They cover the period from 1/12/1976 to 7/5/2007.
http://www.pmodwrc.ch/pmod.php?topic=tsi/composite/SolarConstant
ftp://ftp.pmodwrc.ch/pub/data/irradiance/composite/DataPlots/ext_composite_d41_61_0705.dat
A preprocessing program converted month and day information
into fractional years and removed data marked by PMODWRC as
invalid.
DISCUSSION:
Global warming 'skeptics' often claim that increases in Solar
radiation reaching the top of Earth's atmosphere, not rising CO2
concentrations in the atmosphere, are responsible for the observed
climb of the global mean near surface temperatures in the last
thirty years. This argument was not supported by the facts.
Now it is even less so. When the 11-year solar cycle was
statistically removed, prior data showed no significant long
term change in Solar irradiance large enough to explain the
warming, (about 3 W/m^2 are needed.) Present data actually
show a very small but statistically significant decrease in
solar output over the last three solar cycles. It is very
hard to support any claim of a solar cause for global warming
when measurements clearly show decreasing solar output.
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