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Archive for the ‘GIStemp’ Category

Lines, Sines, and Curve Fitting 6 – backcast and forecast

This is a long post, so I am going to place it behind the “fold.” Click on the read more link to see the curve fits from the previous posts backcast and forecast. This might be a good post to practice your browser’s zoom features.

Lines, Sines, and Curve Fitting 5 – a growth

From the comments in Curve Fitting 4:

If you want to try a different flavor of gum, consider simultaneously fitting exponential + sine models:

y1(t) = y1(0) * exp(kt)
y2(t) = A * sin(((t-b)/T) * 2 * pi)
y(t) = y1(t) + y2(t)

You’ve probably already thought of this, of course.

Ned’s been peeking ahead, so maybe I shouldn’t “reward” him. 😉 But here it is anyway. The procedures are similar. I fitted an exponential with a sine of the residuals, a sine with an exponential of the residuals, and fitting both a sine and exponential simultaneously. I know that there are pre-packaged R methods for fitting exponentials, but I use the method of looking for best fit in by looping through the parameter space.

Lines, Sines, and Curve Fitting 2 — reversi

2011 January 8 1 comment

It seems natural, seeing GISTEMP over the 20th Century, to take the linear trend first. But what if we reverse the order in which we take the trends? Take the sine first and then the linear trend?

Lines, Sines, and Curve Fitting 1 … oh my!

2011 January 7 1 comment

Looking at the 20th century data, it seems that there might be a sinusoidal signal in there some where. For instance …

I’m gonna try to fit a sine wave onto a linear trend.

Did Global Warming Stop After 2007?

One more set of these. This set is up because it shows the best chance to break a recent warm trend. This is because 2008 was relatively low in recent years. Keeping it out of the trend keeps the trend a bit higher and lets a low year kiss the edge of the ‘no trend / cooling trend’ realms.

Did Global Warming Stop in 1940?

I used the data set prepared by O’Day over at Climate Charts & Graphs. Thus, we have charts for GISTEMP, HadCRU, and NOAA. The data for Dec 2010 is still missing – but I’m using the ave for Jan-Nov for the 2010 annual data.

10, 20, 30, 40, 50 and More!

After the turn of the century
In the clear blue skies over Germany
Came a roar and a thunder men had never heard
Like the screamin’ sound of a big war bird

Up in the sky, a man in a plane
Baron von Richthofen was his name
Eighty men tried, and eighty men died
Now they’re buried together on the countryside

Ten, twenty, thirty, forty, fifty or more
The Bloody Red Baron was rollin’ up the score
Eighty men died tryin’ to end that spree
Of the Bloody Red Baron of Germany

In the nick of time, a hero arose
A funny-looking dog with a big black nose
He flew into the sky to seek revenge
But the Baron shot him down – “Curses, foiled again!”

In this set, we look at GISTEMP through different lengths of trend.

Did Global Warming Stop After 2000?

Second verse, same as the first.
So why bother? Completeness.