******************************************************************** *** Atmospheric CO2-curve values (ppmv) derived from flask air *** *** samples collected at American Samoa *** *** *** *** Source: R. F. Keeling, S. C. Piper, A. F. Bollenbacher *** *** and S. J. Walker *** *** Carbon Dioxide Research Group *** *** Scripps Institution of Oceanography (SIO) *** *** University of California *** *** La Jolla, California USA 92093-0444 *** *** *** *** May 2008 *** ******************************************************************** Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann. Ave. 1981 339.08 339.25 339.62 339.96 1982 340.22 340.47 340.54 340.38 340.32 340.48 340.65 340.67 340.59 340.62 340.86 341.12 340.58 1983 341.33 341.59 341.70 341.60 341.63 341.92 342.21 342.36 342.40 342.54 342.88 343.18 342.11 1984 343.40 343.62 343.65 343.44 343.36 343.56 343.79 343.90 343.93 344.06 344.42 344.75 343.82 1985 345.00 345.26 345.33 345.14 345.08 345.32 345.58 345.70 345.71 345.82 346.15 346.45 345.55 1986 346.65 346.86 346.87 346.60 346.46 346.61 346.78 346.79 346.69 346.72 346.99 347.25 346.77 1987 347.44 347.65 347.68 347.45 347.37 347.63 347.93 348.10 348.16 348.35 348.78 349.18 347.98 1988 349.48 349.77 349.85 349.65 349.59 349.86 350.14 350.27 350.29 350.44 350.84 351.20 350.12 1989 351.46 351.70 351.72 351.41 351.24 351.39 351.56 351.57 351.47 351.52 351.86 352.19 351.59 1990 352.44 352.73 352.81 352.58 352.52 352.79 353.08 353.19 353.16 353.26 353.65 354.00 353.02 1991 354.24 354.48 354.47 354.13 353.94 354.09 354.26 354.25 354.11 354.13 354.45 354.75 354.28 1992 354.96 355.21 355.23 354.94 354.83 355.08 355.32 355.35 355.22 355.22 355.51 355.77 355.22 1993 355.92 356.10 356.07 355.71 355.54 355.78 356.06 356.15 356.11 356.22 356.64 357.03 356.11 1994 357.31 357.60 357.63 357.32 357.19 357.45 357.73 357.83 357.79 357.91 358.36 358.78 357.74 1995 359.08 359.41 359.48 359.20 359.10 359.40 359.73 359.85 359.81 359.94 360.39 360.80 359.68 1996 361.08 361.37 361.36 360.97 360.79 361.01 361.24 361.26 361.13 361.18 361.55 361.89 361.24 1997 362.09 362.32 362.29 361.87 361.67 361.92 362.22 362.32 362.29 362.43 362.93 363.40 362.31 1998 363.76 364.15 364.27 364.03 364.02 364.45 364.91 365.13 365.17 365.36 365.88 366.35 364.79 1999 366.66 366.99 367.03 366.65 366.49 366.76 367.05 367.10 366.96 367.01 367.41 367.78 366.99 2000 368.01 368.27 368.22 367.76 367.55 367.83 368.14 368.24 368.18 368.31 368.80 369.26 368.21 2001 369.57 369.90 369.91 369.50 369.30 369.59 369.91 369.99 369.89 369.98 370.47 370.92 369.91 2002 371.25 371.61 371.67 371.30 371.18 371.55 371.96 372.14 372.13 372.31 372.87 373.38 371.95 2003 373.74 374.11 374.16 373.76 373.59 373.90 374.25 374.33 374.23 374.32 374.81 375.27 374.21 2004 375.58 375.91 375.91 375.45 375.25 375.56 375.90 375.99 375.89 376.01 376.55 377.06 375.92 2005 377.42 377.81 377.87 377.47 377.30 377.67 378.06 378.20 378.13 378.28 378.83 379.34 378.03 2006 379.67 380.02 380.01 379.50 379.24 379.52 379.84 379.91 379.80 379.93 380.51 381.06 379.92 2007 381.46 381.90 381.98 381.56 381.39 381.75 382.13 382.23 382.11 382.20 382.71 383.18 382.05 Values above are taken from a curve consisting of 4 harmonics plus a stiff spline and a linear gain factor, fit to monthly concentration values adjusted to represent 2400 hours on the 15th day of each month. Data used to derive this curve are shown in the accompanying graph. Units are parts per million by volume (ppmv) expressed in the 2003A SIO manometric mole fraction scale. The "annual average" is the arithmetic mean of the twelve monthly values.