NSTR
Isaac's 2-stream (0) or Number of DISORT streams (2-32)
Description
The variable NSTR allows selecting method used in the calculation of multiple scattering. The following
options are available:
- If NSTR=0, MODTRAN will use the faster but less accurate Isaac's two-stream algorithm
(Isaacs et al., 1998).
- If NSTR takes one value between 2 and 32, MODTRAN activates the DISORT discrete ordinate multiple scattering
algorithm (Stammes et al., 1988) with the number of streams selected
in NSTR. Using high values generally improves accuracy but slows computation. NSTR=8
(default value) consider enough, although more streams may be
desirable if modeling highly forward peaked scatters.
- If NSTR=-1 is chosen, DISORT calculations are performed
at selected spectral points in the atmospheric window regions. These handfuls of DISORT radiances are then used to
scale Isaac's values for the entire wavelength region.
References
Isaacs, R.G., Wang, W.C., Worsham, R.D., & Goldenberg, S., (1987),
"Multiple/Scattering LOWTRAN and FASCODE models." Applied Optics.
Vol. 26, No. 3, pp. 1272‒ 1281.
Stamnes, K., Tsay, S.-C., Wiscombe, W., & Jayaweera, K., (1988),
"Numerically Stable Algorithm for Discrete-Ordinate-Method Radiative Transfer in Multiple Scattering and Emitting Layered Media." Applied Optics.
Vol. 27, No. 3, pp. 2502‒ 2509.