"Climate change is one of the greatest environmental challenges today, with the potential to significantly alter how we live. It is largely attributable to human activity where greenhouse gases (GHG) are released into the atmosphere. The oceans exert a considerable influence on the atmosphere by absorbing a large fraction of GHGs, but there remain large uncertainties in the budget. This underscores the importance of conducting research concerned with air-sea gas fluxes in order to work toward a reduction in these uncertainties. The scientific objectives of this proposal are to simultaneously measure the fluxes of climatically relevant compounds in both the coastal and oceanic marine atmospheric boundary layer. The proposed species are carbon dioxide, methane, nitrous oxide, and carbon monoxide. All species will be detected at 1-10 Hz, which will allow for fluxes to be directly determined using the eddy correlation method. This proposed method takes advantage of recently-developed trace gas analyser (TGA) technology. The TGA will be deployed at the Mace Head Research Station where a time series over several years will be acquired. The system will also be deployed periodically on research ships to compare the magnitude of the fluxes in the coastal regions with open ocean data. If funded, this measurement will be one of the first of its kind deployed in the marine atmospheric boundary layer, and will provide an invaluable time series of the fluxes over an extended period. The Returning Research Fellow (RRF) for this proposal has spent the previous 7 years as a fulltime researcher in the field of air--sea exchange in the USA, where he has established a level of excellence in gaining funding and conducting research. Funding from the IRG programme will allow the RRF to establish a research programme in Europe, with the objective of fully integrating into the European Research Area."