Retrieval of structure functions of air temperature and refractive index from large eddy simulations of the atmospheric boundary layer

A methodology is presented to infer the refractive-index structure function parameter and the structure parameters for temperature and humidity from numerical simulations of the turbulent atmospheric convective boundary layer (CBL). The method employs spatial and temporal averaging of multiple realizations of the CBL flow field reproduced by a large-eddy simulation (LES) of the atmosphere. The C-n(2) values yielded by LES-based approach agree fairly well with C-n(2) values predicted by the Monin-Obukhov similarity theory. In this respect, the C-n(2) retrieval from the LES data is promising for evaluating the vertical profile of C-n(2) throughout the entire CBL. Under the considered CBL conditions and for the selected optical wavelength of 0.55 mu m the value of C-n(2) was found to be dominated by the C-T(2) contribution in the first few hundred meters above the surface, whereas the C-Tq contribution became significant aloft.