Abstract: In the clear atmosphere, refractive index turbulence severely limits a variety of optical remote sensing techniques, such as imagers of laser remote sensors. To calculate the limiting effect of turbulence, the structure function constant C$-n$/$+2$/ of the refractive index fluctuations must be known. Certain cases also require knowledge of the inner scale l$-0$/ of refractive index turbulence. The largest values of C$-n$/$+2$/ occur in the atmospheric boundary layer. For the boundary layer over land, a number of models has been developed and experimentally tested so far. However, only few data are available for the boundary layer over sea. This paper describes a simple model for the marine boundary layer. The model uses Monin-Obukhov similarity relationships between C$-n$/$+2$/ and l$-0$/ and the turbulent fluxes of heat and momentum. The turbulent fluxes are calculated from a bulk parameterization scheme. Main input parameters are air temperature, sea surface temperature and wind speed. Model predictions are compared with experimental data from the SWAP 1993 campaign in the North Sea. Here C$-n$/$+2$/ and l$-0$/ were measured with two scintillometers over path lengths of 100 m and 190 m. The comparison demonstrates the capability of this modelling approach.!7
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