Background atmospheric CO₂ mixing ratios from individual flask air samples for the Azores. Only measurements satisfying the data selection criteria fro background measurements are plotted. Consecutive background measurements are joined by lines. Background measurements interrupted by non-background measurements are not joined by lines.

Monthly atmospheric CO2 mixing ratios for the Azores expressed in parts per 
million (ppm) and reported in the Scripps Institution of Oceanography X93 manometric mole fraction scale.  
Annual values were calculated by CDIAC for years with complete records.  Missing values are denoted by -99.99.



Year      Jan 	     Feb      Mar	April	  May	   June	     July      Aug     Sept	  Oct 	   Nov       Dec     Ann




1979    -99.99     -99.99   -99.99     -99.99   -99.99    -99.99    -99.99   -99.99   -99.99     -99.99   -99.99    339.21   -99.99
1980    340.20     341.74   342.31     342.11   341.83    340.66    337.60   334.32   333.64     335.88   338.70    340.05   339.09
1981    340.40     342.02   343.66     344.18   343.49    340.27    336.78   334.48   333.91     336.22   338.63    340.65   339.56
1982    341.99     343.37   345.29     346.23   345.06    342.17    336.30   332.50   334.96     339.23   343.17    344.52   341.23
1983    345.08     345.48   344.89     345.42   345.32    343.65    341.49   338.43   337.35     339.85   343.33    344.78   342.92
1984    346.48     348.08   347.48     346.80   347.81    345.26    340.94   339.07   339.21     341.45   344.65    346.45   344.47
1985    346.60     347.90   350.25     350.66   348.72    345.88    341.68   338.47   340.53     345.21   347.91    349.01   346.07
1986    349.62     349.33   349.52     350.72   350.64    350.11    348.22   345.67   345.34     347.25   349.19    348.94   348.71
1987    348.44     349.71   352.01     353.11   351.07    348.68    347.44   344.41   342.52     345.97   349.30    350.74   348.62
1988    352.22     353.11   353.17     354.04   353.35    351.55    350.18   347.94   346.55     349.27   353.01    354.51   351.58
1989    354.24     354.83   357.31     357.46   355.77    353.17    -99.99   -99.99   -99.99     -99.99   -99.99    -99.99   -99.99
1990    -99.99     -99.99   -99.99     -99.99   -99.99    -99.99    -99.99   -99.99   -99.99     352.76   356.52    357.96   -99.99
1991    357.87     357.97   359.87     361.04   359.25    358.50    355.29   350.33   350.26     352.38   353.81    354.45   355.92
1992    355.42     -99.99   -99.99     -99.99   -99.99    -99.99    -99.99   -99.99   -99.99     -99.99   -99.99    -99.99   -99.99