`Final set of parameters Asymptotic Standard Error`

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```
```

`a = 2.94186 +/- 0.01424 (0.484%)`

b = 0.849263 +/- 0.01432 (1.686%)

m = 2.04229 +/- 0.002769 (0.1356%)

c = 384.608 +/- 0.01061 (0.00276%)

phi6 = 0.446317 +/- 0.00134 (0.3001%)

phi12 = 0.297225 +/- 0.000778 (0.2618%)

Annual variation in CO2 at MLO appears to be a combination of a 12 month and 6 month cycle plus a long term rise.

Over short temporal range the long term can be modelled as linear.

The 12mo cycle presumably represents a net effect of opposing NH and SH extra-tropical variation and the 6mo cycle is due to the ‘seasons’ of the tropical zones.

The cross-over points of the dual-linear model are:

2009.37, 390.975

2009.73, 384,103

2010.37, 392.964

giving rise and fall periods of 0.64 and 0.36 , very close to 2:1 ratio.

Peak to peak annual variation ~ 6ppmv

Mauna Loa Observatory, Hawaii: Latitude 19.5°N

Longitude 155.6°W Elevation 3397m

**Data Source: Scripps Institute**

http://scrippsco2.ucsd.edu/data/atmospheric_co2.html