Phase Function Specification

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Phase Function Specification#

Generally in SASKTRAN2 the phase function is specified in terms of it’s Legendre coefficient expansion. The number of coefficients in the expansion determines the accuracy of the calculation, however a different number of expansion terms are used in the single scatter and multiple scatter calculations. The number of expansion terms for each is controlled by sasktran2.Config.num_singlescatter_moments and sasktran2.Config.num_streams respectively.

Delta-m Scaling#

SASKTRAN2 has the capability to perform Delta-m scaling, where strong forward peaks of the phase functions are handled in an approximate fashion. Generally the approximation performs very well for situations where you are not directly observing the forward scatter peak of a strong forward scatterer such as a cloud.

Delta-m scaling is disabled by default in SASKTRAN2, however it can be explicitly enabled with

import sasktran2 as sk

config = sk.Config()

config.delta_m_scaling = True # False

As with most things, the performance of delta-m scaling depends heavily on the specific application. The best way to determine if it is useful for your specific calculation is to compare your results to a calculation with a large number of streams.

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