MEAN PROFILES OF TRACE REACTIVE SPECIES IN THE UNPOLLUTED MARINE SURFACE LAYER.

Several aspects of trace gas photochemistry in the marine boundary layer were investigated using a time-dependent transport-kinetics model with one-dimensional eddy diffusion. The photochemical scheme in the model is represented by a conventional complement of reactions involving O, H, N, and methane-derived organic species; boundary conditions are assigned which give low surface mixing ratios of O//3 and NO//x characteristic of the remote marine environment. Particular attention has been given to the distribution of odd nitrogen and the NO//2-NO-O//3 photostationary state in the surface boundary layer. Calculated profiles of NO, NO//2, O//3, and HNO//3 show definite gradients in the surface layer. When the ocean is assumed to be a source of NO, mixing ratios on the order of a few parts per trillion can be supported by an upflux of approximately 10**8 cm** minus **2 s ** minus **1. If a surface input of NO is not assumed, NO//x levels are much lower. Calculated values of the O//3-NO-NO//2 photostationary state ratio, R//p//s, and NO/HNO//3 show appreciable variation within the surface layer. The latter ratio is sensitive to the NO upflux and to heterogeneous removal of HNO//3.