Calculations were performed for all combinations of the following parameters:
Wavelengths: 325nm, 450nm, 765nm, 1700m
Viewing angle range: 0° - 60°, 5° increment
Solar zenith angles: 0°, 30°, 60°, 80°
Solar azimuth angles: 0°, 40°, 150°, 220°
Surface albedos: 0, 0.2, 0.8
Each case was computed for the following scenarios with and without polarization.
Output: Normalized radiance (I Q U V)/E_0
Rayleigh scattering coefficients were computed according to Bodhaine 1999, Eq. 29 for a 100 layer equidistant model atmosphere (US Standard, Anderson 1986). The following files include the coefficients as calculated on the 101 levels or averaged for the 100 model layers:
The Rayleigh scattering matrix is well known:
θ is the scattering angle and δ the depolarization factor, which is also calculated from Bodhaine 1999: depol.dat
The following plots show the results of all vector calculations:
Lines correspond to the SCIATRAN results and crosses to MYSTIC results. The results agree within the Monte Carlo noise (<0.5% for I, <1% for Q, U, V is zero for Rayleigh scattering).
The SCIATRAN results (analytical) may be used as benchmark, we do not provide MYSTIC results because of Monte Carlo noise.
Benchmark data (SCIATRAN): st_rayleigh.nc
In a real atmosphere the molecules also absorb radiation, the next scenarios are for a realistic molecular atmosphere including scattering and absorption. The absorption coefficients are calculated using the libRadtran model which includes absorption coefficients of all relevant atmospheric species. For 1700 nm the absorpion parameterization based on representative wavelengths (Gasteiger et al 2013) was used:
The agreement of the models is similar to the cases without absorption.
Cloud in 2-3 km altitude, optical thickness: 10
Optical properties are provided in the following files:
The variable “phase” includes the phase matrix, as a function of the scattering angle (variable “theta”). The 4×4 scattering phase matrix for spherical droplets has four non-zero elements, which are stored in the following order:
The single scattering albedo and the extinction coefficient are also stored in the files.
The absorption coefficients in the O2A band have been calculated for the midlatitude-summer atmosphere using the ARTS model. They are based on the HITRAN2004 line cataloque.
The spectra are calculated for all viewing geometries and solar zenith angles defined above. The surface albedo was constantly 0.2.
Benchmark results (SCIATRAN): st_o2_spec.nc