The influence of atmospheric profile resolution on modelling propagation effects in high-elevation scenarios

Using seasonally averaged meteorological and spectrally resolved aerosol profiles extracted from a maritime environment, this paper investigated how the resolution of the vertical profiles influences the 3 and 8 average transmittance and integrated path radiance computations conducted by MODTRAN in high-elevation scenarios. First, the minimum altitude to which the atmosphere should be defined in order to accurately determine the transmittance and path radiance along vertical and slant paths was investigated by recursively removing vertical layers until the relative changes in the transmittance and path radiance became smaller than those due to instrument uncertainty. Once this minimum height was found, the vertical resolution in the atmosphere below the minimum altitude was systematically varied. The suitability of several gradient-based criteria has been investigated to determine the optimal discretization of the vertical profiles. The results indicate that, depending on the quantity to be calculated, vertical discretizations based on the gradient in either the pressure, temperature or humidity serve as optimal discretizations in maritime high-elevation scenarios. Moreover, the followed methodology demonstrates how to adaptively implement a vertical resolution in a generic atmosphere, which generates crucial knowledge in supporting signature and sensor performance modelling for high-elevation scenarios.