The SSSS scheme: a method for calculating multiple scattering of electromagnetic radiation by a collection of sparsely spaced spherical scatterers of Mie-scattering size based on first principles
Carynelisa Haspel and Idan Cohen, "The SSSS scheme: a method for calculating multiple scattering of electromagnetic radiation by a collection of sparsely spaced spherical scatterers of Mie-scattering size based on first principles," Appl. Opt. 61, 8563-8577 (2022)
We present a method for calculating multiple scattering of electromagnetic radiation by a collection of sparsely spaced spherical scatterers (SSSS) of Mie-scattering size based on first principles rather than radiative transfer theory. In this respect, our methodology is conceptually similar to the superposition $T$-matrix method. However, our implementation, which we call the SSSS scheme, differs in a number of respects. Overall, the SSSS scheme is simpler, it is better suited numerically to sparse spacing, and the computer memory required is only linearly dependent on the total number of scatterers. We suggest that the SSSS scheme would be particularly useful for examining the effects of different spatial configurations of drops within water clouds in Earth’s atmosphere and would also be useful in other fields of research in which the exact configuration of a collection of sparsely spaced Mie-sized scatterers is important.
The SSSS scheme and the output shown in this study can be obtained from the authors by request.
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Clouds Generated for this Study Using Our Cloud Generating Algorithm
Cloud Label
Monodisperse (M) or Polydisperse (P)
Cloud Dimensions
M1
M
3
M2
M
300
M3
M
30,000
M4
M
300,000
P1
P
3
P2
P
300
P3
P
30,000
P4
P
300,000
Table 2.
Single-Scattering Parameters and Reflection for the Eight Clouds Investigated in this Study, as Calculated Using the Delta-Eddington Exponential-Sum-Fit Radiative Transfer Model of [43,44]
For all four monodisperse clouds, ${k_{{\rm ext}}} = 3 \times 10^8\;{\rm m}^{-3}\times 2.029276 \times \pi \times (10.0\times 10^{-6}\;{\rm m})^2$.
The values of single scattering albedo and asymmetry factor are conventionally written with more significant figures than the precision with which the other parameters are given.
Table 3.
Reflection for the Eight Clouds Investigated in this Study as Calculated Using the SSSS Scheme
Cloud
SSSS Scheme
M1
M2
M3
M4
P1
P2
P3
P4
Table 4.
Orders of Scattering to Converge and Run Times to Convergence Using the SSSS Scheme on the Clouds Investigated in this Study (refer to Table 1)
Cloud
Orders of Scattering to Converge
Run Time to Convergence
M1
5
0 s
M2
7
1 s
M3
10
211 s
M4
9
18,300 s
P1
5
0 s
P2
6
1 s
P3
9
17,156 s
P4
13
Table 5.
Percent Difference in Values of the Scattering Phase Functions between Order 0 (No Interaction between Drops) and the Full, Converged SSSS Solution
Cloud Label
Mean % Diff; Full
Max % Diff; Full
Mean % Diff;
Max % Diff;
M1
2%
323%
(43°,170°)
0.2%
7%
90°
M2
7%
4865%
(164°,123°)
0.5%
12%
89°
M3
7%
2985%
(34°,87°)
0.7%
27%
90°
M4
2%
579%
(166°,221°)
0.1%
2%
90°
P1
3%
315%
(1°,331°)
0.3%
7%
180°
P2
5%
3313%
(4°,100°)
0.4%
10%
90°
P3
5%
453%
(17°,348°)
0.4%
10%
91°
P4
2%
206%
(104°,332°)
0.1%
2%
180°
Table 6.
Percent Difference in Values of the Scattering Phase Functions between Order 1 (Single Interaction between Drops) and the Full, Converged SSSS Solution
Cloud Label
Mean % Diff; Full
Max % Diff; Full
Mean % Diff;
Max % Diff;
M1
0.02%
2%
(106°,335°)
0.002%
0.09%
90°
M2
0.2%
50%
(91°,268°)
0.008%
0.4%
89°
M3
0.3%
48%
(65°,61°)
0.02%
0.7%
91°
M4
0.1%
60%
(92°,269°)
0.006%
0.5%
91°
P1
0.02%
1%
(1°,331°)
0.004%
0.08%
180°
P2
0.08%
9%
(98°,9°)
0.005%
0.4%
90°
P3
0.2%
28%
(90°,1°)
0.01%
0.6%
91°
P4
0.1%
13%
(91°,268°)
0.005%
0.02%
91°
Tables (6)
Table 1.
Clouds Generated for this Study Using Our Cloud Generating Algorithm
Cloud Label
Monodisperse (M) or Polydisperse (P)
Cloud Dimensions
M1
M
3
M2
M
300
M3
M
30,000
M4
M
300,000
P1
P
3
P2
P
300
P3
P
30,000
P4
P
300,000
Table 2.
Single-Scattering Parameters and Reflection for the Eight Clouds Investigated in this Study, as Calculated Using the Delta-Eddington Exponential-Sum-Fit Radiative Transfer Model of [43,44]
For all four monodisperse clouds, ${k_{{\rm ext}}} = 3 \times 10^8\;{\rm m}^{-3}\times 2.029276 \times \pi \times (10.0\times 10^{-6}\;{\rm m})^2$.
The values of single scattering albedo and asymmetry factor are conventionally written with more significant figures than the precision with which the other parameters are given.
Table 3.
Reflection for the Eight Clouds Investigated in this Study as Calculated Using the SSSS Scheme
Cloud
SSSS Scheme
M1
M2
M3
M4
P1
P2
P3
P4
Table 4.
Orders of Scattering to Converge and Run Times to Convergence Using the SSSS Scheme on the Clouds Investigated in this Study (refer to Table 1)
Cloud
Orders of Scattering to Converge
Run Time to Convergence
M1
5
0 s
M2
7
1 s
M3
10
211 s
M4
9
18,300 s
P1
5
0 s
P2
6
1 s
P3
9
17,156 s
P4
13
Table 5.
Percent Difference in Values of the Scattering Phase Functions between Order 0 (No Interaction between Drops) and the Full, Converged SSSS Solution
Cloud Label
Mean % Diff; Full
Max % Diff; Full
Mean % Diff;
Max % Diff;
M1
2%
323%
(43°,170°)
0.2%
7%
90°
M2
7%
4865%
(164°,123°)
0.5%
12%
89°
M3
7%
2985%
(34°,87°)
0.7%
27%
90°
M4
2%
579%
(166°,221°)
0.1%
2%
90°
P1
3%
315%
(1°,331°)
0.3%
7%
180°
P2
5%
3313%
(4°,100°)
0.4%
10%
90°
P3
5%
453%
(17°,348°)
0.4%
10%
91°
P4
2%
206%
(104°,332°)
0.1%
2%
180°
Table 6.
Percent Difference in Values of the Scattering Phase Functions between Order 1 (Single Interaction between Drops) and the Full, Converged SSSS Solution