Daily CO2 data for Alert station, Canada from Scripp’s Institute was used, excluding data marked by the provider as non representative of background levels.

Non linear least squares was used to fit the model. However, it did not converge well with respect to the parameters of the small cosine, so these were fitted by inspection and least squares used to adjust the remaining terms.

Due to a long term deviation in the underlying trend the fit was limited to 1993 onwards.

Down slope in Alert 59 ppmv / year

Date of minimum in model year+0.69 ; peak to peak variability 18 ppmv. The average maximum is at year+0.18, near 7th March.

The data from Alert at 82N is strikingly similar to Schauinsland in southern Germany:

https://climategrog.wordpress.com/?attachment_id=985

Fitted model: co2(x)=lin(x)+abscos2(x)+cos1(x) where abscos2(x)=a2*abs(cos(2*pi*(x-yz2)/p2)) cos1(x)=a1*(cos(2*pi*(x-yz1)/p1)) lin(x)=m*(x-yz1)+c fixed parameters: a1=1.5; p1=0.5; p2=2.0; yz1=2000.40; NLLS fitted parameters: Final set of parameters Asymptotic Standard Error ======================= a2 = 18.2207 +/- 0.1628 (0.8936%) yz2 = 2006.18 +/- 0.4065 (0.02026%) c = 359.301 +/- 0.1187 (0.03302%) m = 1.94655 +/- 0.008696 (0.4468%) correlation matrix of the fit parameters: a2 yz2 c m a2 1.000 yz2 -0.023 1.000 c -0.892 0.034 1.000 m 0.020 -0.017 -0.186 1.000 .

Alert, NWT, Canada: Latitude 82.3°N Longitude 62.3°W° Elevation 210m

**Data courtesy of Scripps Institute**

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