The Ar/N2 ratio of air measured at 6 globally distributed sites shows annual cycles with amplitudes of 12 to 37 parts in 106. Summertime maxima reflect the atmospheric Ar enrichment driven by seasonal warming and degassing of the oceans. Paired models of air-sea heat fluxes and atmospheric tracer transport predict seasonal cycles in the Ar/N2 ratio that agree with observations, within uncertainties.
Battle, Mark; Bender, Michael; Hendricks, Melissa B.; Ho, David T.; Mika, Robert; McKinley, Galen; Fan, Song Miao; Blaine, Tegan; and Keeling, Ralph F., "Measurements and models of the atmospheric Ar/N2 ratio" (2003). Physics Faculty Publications. 20.