Carbon Dioxide Concentration

Mole fraction of atmospheric carbon dioxide (xCO2) near the surface in units of micromoles per mole (µmol/mol). For instance, an xCO2 of 400 µmol/mol indicates that a mole of air contains 400 micromoles of CO2, or 400 millionths of a mole, or 0.0004 mole.

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