How are the f1850 and f2000 aerosol, ozone data and ghg concentration parameter made? ?

I see that the f1850 sst data is a climotology of 1870-1899,f2000 is a climo of present. Then how is the f1850 and f2000 aerosol ozone and ghg data made? Are they also a climo of the same time? Or some different period?
 
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