Simulation and performance studies of a spectral sunphotometer for the ER-2 aircraft

Abstract

Simulations were performed to assess the performance capabilities of a proposed design for an airborne spectral sunphotometer to operate on the NASA ER-2 aircraft. The detector system characteristics were simulated for typical operation conditions, and the results suggest that it is capable of achieving the scientific objectives of the ER-2 sunphotometer. A simulation program was developed for the retrievals of the optical depth, extinction/absorption coefficient at selected wavelengths, including a detailed error component analysis. The last function is particularly important for achieving high accuracy retrievals, since it allows one to trace back the error sources, and correspondingly make adjustments in data sensing or flight parameters. Models of the diffuse light dependencies airmass, wavelength, and Rayleigh and aerosol optical depth were also established. An correction method was constructed based on these models to permit high accuracy retrievals. Simulation results show that this scheme is highly accurate.