Home > CRUTEMP, GIStemp, LSCF, models, Statistics > Lines, Sines, and Curve Fitting 11 – more extrapolation

## Lines, Sines, and Curve Fitting 11 – more extrapolation

2011 January 19

I’ve mostly been working through GISTEMP in this series, but the exp+sine results were interesting enough that I wanted to pause and look at both line+sine and exp+sine in all three data sets.

In order to show these on a common graph, I adjusted the CRU data up slightly.

```delta <- (mean(noa) + mean(gis))/2 - mean(cru)
delta
[1] 0.1038117```

m3*x + b3 + A3 * sin(((x-B3)/T3)*(2*pi)

```  m            b         A         B          T
GIS 0.005725367 -11.16459 0.1050844 68.06118 58.15746
CRU 0.005734433 -11.28999 0.1351174 30.99897 59.23351
NOA 0.005459401 -10.61768 0.1300066 32.04425 59.21759```
```> cor(y3[,1],y[,1]) # GISTEMP
[1] 0.9194656
[1] 0.9145043
> cor(y3[,3],y[,3]) # NOAA / NCDC
[1] 0.9223988```

-a4/100 + b4/100 * exp((k4/10000)*(x-1880))+ A4 * sin(((x-B4)/T4)*(2*pi)

```    a         b          k           A         B         T
GIS 39.39528 11.34487 158.5761 0.08123327 1857.690 66.71628
CRU 58.50143 17.07027 132.0417 0.11238451 1801.812 61.63521
NOA 37.78438 12.43439 150.1897 0.10528688 1863.281 62.17947```
```> cor(y4[,1],y[,1]) # GISTEMP
[1] 0.9314415
[1] 0.9275221
> cor(y4[,3],y[,3]) # NOAA / NCDC
[1] 0.938808```

If the sine signal really exists in the physical system, the temperature increases we have seen over the last 30 years are going to slow considerable. If the exp + sine is a realistic model, the global temp anomaly will only see an increase of about 0.1C – 0.2C over the next 20 years. Compare this with an increase of about .3C over the last 20 years. If the line+sine is a realistic model, global temp anomalies will drop over the next 20 years

Exp + Sine increase from 2011 – 2030:

# GISTEMP: 2030 – 2011
(yy4[151,1] – yy4[132,1])
0.2005237

(yy4[151,2] – yy4[132,2])
0.09768462

# NOAA/NCDC: 2030 – 2011
(yy4[151,3] – yy4[132,3])
0.1239707

1. 2011 January 20 at 6:46 pm

RON

“If the sine signal really exists in the physical system, the temperature increases we have seen over the last 30 years are going to slow considerable. If the exp + sine is a realistic model, the global temp anomaly will only see an increase of about 0.1C – 0.2C over the next 20 years. Compare this with an increase of about .3C over the last 20 years. If the line+sine is a realistic model, global temp anomalies will drop over the next 20 years”

Thanks so much for your work and your conclusions that I agree completely.

Ron, you rely “verify”!

You know RealClimate.org will not agree with your conclusions!

With all my best wishes Ron.

2. 2011 January 28 at 9:53 pm

I accidentely posted on an old trhread here. I will repeat it here in case you miss it!
I have updated the multi-frequency approximation to HADCRUT3V.
I Have used your Idea of 2 frequencies+ trend the 2 frequencies + trend+TSI, and then all that + the other frequencies.

The 2 major frequencies are:
59.4167 years
103.5000 years.

TSI has no great effect

http://climateandstuff.blogspot.com

Mike

1. 2011 February 10 at 10:02 pm
2. 2011 February 13 at 10:41 am
3. 2012 February 16 at 6:46 pm
4. 2012 February 16 at 6:47 pm