Rotational Raman scattering in the Earth's atmosphere ... - SRON

26 Chapter 2
Figure 2.2: Filling-in for a model layer with ω ray = 1 and τ = 0.4 which is irradiated by a synthetic
solar spectrum with the Fraunhofer line in Eq. (2.20). The upper panel shows the filling-in f ref versus
wavelength λ for a fixed optimized wavenumber grid with n max = 3 and ǫ = 10 −6 . Below is the
difference with f ref versus threshold ǫ at the line center at λ = 393.48 nm (left) and at the continuum at
λ = 398.18 nm (right) for n max = 1, 2, 3. For a threshold of ǫ = 10 −2 only the Cabannes line is selected,
which results in f −f ref = −17.25% at the line center (falls outside range). All calculations were done
for a fixed geometry with solar zenith angle ϑ 0 = 60 ◦ , viewing angle ϑ v = 30 ◦ and azimuthal angle
difference ϕ v −ϕ 0 = 10 ◦ . Four Gaussian quadrature points were used to describe the internal radiation
field. Furthermore, a Gaussian instrument function with a full width at half maximum of 0.2 nm was
applied to simulate GOME-type measurements.