Background atmospheric CO₂ mixing ratios from individual flask air samples for Sand Island. 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 Sand Island, 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




1985    -99.99     -99.99   -99.99     -99.99   349.99    348.71    347.00   344.52   342.17     343.21   345.62    346.64   -99.99
1986    348.16     349.47   349.66     350.32   351.25    350.29    348.17   344.69   342.62     344.78   347.58    348.97   348.00
1987    350.32     350.90   351.58     353.23   353.50    351.95    349.36   345.50   344.52     347.14   349.42    350.89   349.86
1988    352.81     353.88   353.94     354.97   355.77    355.06    353.18   350.56   349.51     350.84   351.95    352.91   352.95
1989    354.43     355.15   355.94     357.66   357.58    356.24    353.14   348.48   348.89     352.16   353.82    355.72   354.10
1990    356.41     356.92   357.90     358.70   358.42    356.55    353.81   350.83   350.33     352.28   354.16    355.53   355.15
1991    357.10     358.58   358.91     360.23   360.94    358.53    355.83   353.67   352.56     354.40   356.25    357.20   357.02
1992    358.24     359.13   359.75     360.47   360.59    358.09    355.53   353.14   351.86     352.99   354.92    356.77   356.79
1993    358.31     359.05   359.29     360.74   361.58    359.09    356.81   354.27   352.39     354.46   356.87    357.91   357.56