Modeling the tropical cyclone-induced biological flux of carbon Into the thermocline

A high-resolution model is presented, using established techniques to resolve mixed layer dynamics and the carbon cycle, including chemical and biological sources and sinks, in response to tropical cyclone-induced turbulent mixing. Its ability to recreate the observed ocean state is tested. Using the best estimates of real storms, it is shown that, at least in the case of strong mixing events, the induced biological processes represent a credible net sink of carbon from the atmosphere into the deep ocean, as well as a net sink of dissolved inorganic carbon from the mixed layer to the deep ocean. However, the same processes are capable of producing a net outgassing of CO2 from the ocean to the atmosphere, depending sensitively on the state of the ocean at the time of the cyclone and the depth of the mixing. Therefore caution must be taken to ensure that both the ocean state preceding the tropical cyclone and the depth of the mixing are accurately characterized.