Earth: Molecular Abundances

From US Standard Atmosphere 1976, Table 3 and page 33 (Trace Constituents)

Gas	<mw> gm/mole
H	1.00794
C	12.011
N	14.00674
O	15.9994
S	32.066

Gas	<mw> gm/mole	volumetric fi
N2	28.0134	0.78084
O2	31.9988	0.209476
Ar	39.948	0.00934
CO2	44.00995	314 ppmv
Ne	20.183	18.18 ppmv
He	4.0026	5.24 ppmv
Kr	83.80	1.14 ppmv
Xe	131.30	0.087 ppmv
CH4	16.04303	1.5 ppmv
H2	2.01594	0.5 ppmv
<<mw>>	28.9644
H2O	18.016	f 0.005 at 1 km (900 mB)
O3	47.9982	f 20 ppmv at 36 km (5 mB)
N2O	44.0129	270 ppbv
NO	30.0061	0.5 ppbv
NO2	46.0055	1 ppbv
H2S	34.0819	0.05 ppbv
NH3	17.0306	4 ppbv
SO2	64.0648	1 ppbv
CO	28.0104	190 ppbv

Methane, CH₄
1992 1.7086 ppm
1984 1.6180 ppm --> +0.0113 ppm/year = +0.7 %/year
0.02 ppm peak-to-peak seasonal variation = ± 0.01 ppm = ± 0.62 %
q_CH4 = 1.618 + 0.0113 · (t-1984.0) ± 0.01 ppm

Carbon Dioxide, CO₂
1995 361.0 ppm
1980 336.8 ppm --> +1.6 ppm/year = +0.475 %/year
0.105 ppm peak-to-peak seasonal variation = ± 0.052 ppm = ± 0.015 %
q_CO2 = 337 + 1.6 · (t-1980.0) ± 0.052 ppm

C¹²O¹⁶O¹⁸ = 4.08 · 10^-3 · C¹²O¹⁶O¹⁶
C¹²O¹⁶O¹⁷ = 7.42 · 10^-4 · C¹²O¹⁶O¹⁶     Kiehl & Ramanathan 1983. JGR 88 p.5191.
C¹³O¹⁶O¹⁶ = 1.12 · 10^-2 · C¹²O¹⁶O¹⁶