An atmospheric constraint on the seasonal air-sea exchange of oxygen and heat in the extratropics

The total air-sea exchange of O-2 has been shown to be closely related to the air-sea exchange of heat on seasonal timescales, with the ratio of the seasonal flux of O-2 to heat varying with latitude, being higher in the extratropics and lower in the subtropics. This O-2/heat ratio is both a fundamental biogeochemical property of air-sea exchange and a convenient metric for testing earth system models.

Current estimates of the O-2/heat flux ratio rely on sparse observations of dissolved O-2, leaving it fairly unconstrained. From a model ensemble we show that the ratio of the seasonal amplitude of two atmospheric tracers, atmospheric potential oxygen (APO) and the argon-to-nitrogen ratio (Ar/O-2), exhibits a close relationship to the O-2/heat ratio of the extratropics (40-70 degrees). The amplitude ratio, A(APO)/A(ArN2), is relatively constant within the extratropics of each hemisphere due to the zonal mixing of the atmosphere.