This project includes a multi-faceted analysis of marine carbonyl sulfide emissions to be coordinated by a collaborative team from institutions in the US, Germany, and Israel. Carbonyl sulfide is a trace gas capable of providing insight into the global carbon cycle. Mass balance estimates from isotopes and atmospheric inversions both suggest the missing sources of carbonyl sulfide are tied to marine fluxes. This effort will significantly increase understanding of the marine source of carbonyl sulfide (OCS) by conducting a series of coordinated experiments that combine: (1) direct marine flux measurements of OCS; (2) dissolved measurements of OCS and its isotopologues and precursor gasses; and (3) data assimilation and modeling. The project includes an extended field campaign to continuously measure the direct fluxes of OCS. The team will collect data using an air-sea interaction tower on the US Atlantic seaboard (near Martha’s Vineyard, MA) and in Bolkins Eck (Bering Sea), as well as using shipboard measurements to quantify fluxes and resolve sources (via sulfur isotopes) of OCS from these coastal sites. The project includes training for early-career scientists and graduate students from a team of experienced scientists. This work is supported by the Atmospheric Chemistry and the Chemical Oceanography Programs. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader i