4. Input optical thickness
– It is recommended to input one or several values of the optical thickness
(depending on the answer to question 1) pressing the button “Enter” every
time. The range of values is 0.1–2.0 for the clear atmosphere or 2–20 for
cloudy atmosphere. Values from the Table 12.1 might be use;
If the dependency on one parameter is studied (e.g. optical thickness) the set of
several (e.g.10) parameter values is input and other parameters are repeated the
same.
5. Input single scattering albedo (SSA)
– It is recommended to input one or several values of the SSA (depending on
the answer to question (1). The range of values is 0.7 in case of strong
absorption in the clear atmosphere, till 0.999 weak absorption in the cloudy
atmosphere, the value 1.0 for pure (conservative) scattering is better to
change for 0.99999999, otherwise the overflow might be happen. If only
optical thickness is varied, input the same value of SSA several times;
6. Input phase function asymmetry parameter – It is recommended to input the
phase function parameter, if there are several variants input all needed values
pressing the button “Enter”. The range of values is 0 (isotropic scattering –
possible to use for the clear and pure atmosphere) till 0.85 (extended phase
function in clouds)
7. Input ground albedo
– It is recommended to input one or several values of the ground albedo
(depending on the answer to question (1). The range of values is 0, 0.02
(the absence of the surface reflection above sea surface) till 0.95 (strong
reflection by fresh snow);
8. Input solar incident angles (degrees)
– It is recommended to input one or several values of the solar incident angle
(depending on the answer to question 2 in ranges: 0
(the Sun is in zenith) till
80
(the Sun is near the horizon).
Then the program accomplishes the calculation and output the result to the
screen and to the resulting file “eddaer.dat”, where are also input values of the
optical model
Table 12.1 The optical model of the clear atmosphere
l, mm 0.36
0.4
0.45
0.5
0.55
0.6
0.65
0.7
0.8
0.9
t as
0.379 0.316 0.285 0.264 0.250 0.237 0.224 0.213 0.201 0.190
t aa
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
t ms
0.564 0.364 0.223 0.145 0.098 0.072 0.052 0.039 0.023 0.014
t 0
0.983 0.720 0.552 0.449 0.388 0.349 0.316 0.292 0.264 0.244
o 0
0.959 0.944 0.927 0.911 0.897 0.885 0.873 0.863 0.849 0.836
g
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
126
12 Calculating Solar Irradiance with Eddington Method
– It is recommended to input one or several values of the optical thickness
(depending on the answer to question 1) pressing the button “Enter” every
time. The range of values is 0.1–2.0 for the clear atmosphere or 2–20 for
cloudy atmosphere. Values from the Table 12.1 might be use;
If the dependency on one parameter is studied (e.g. optical thickness) the set of
several (e.g.10) parameter values is input and other parameters are repeated the
same.
5. Input single scattering albedo (SSA)
– It is recommended to input one or several values of the SSA (depending on
the answer to question (1). The range of values is 0.7 in case of strong
absorption in the clear atmosphere, till 0.999 weak absorption in the cloudy
atmosphere, the value 1.0 for pure (conservative) scattering is better to
change for 0.99999999, otherwise the overflow might be happen. If only
optical thickness is varied, input the same value of SSA several times;
6. Input phase function asymmetry parameter – It is recommended to input the
phase function parameter, if there are several variants input all needed values
pressing the button “Enter”. The range of values is 0 (isotropic scattering –
possible to use for the clear and pure atmosphere) till 0.85 (extended phase
function in clouds)
7. Input ground albedo
– It is recommended to input one or several values of the ground albedo
(depending on the answer to question (1). The range of values is 0, 0.02
(the absence of the surface reflection above sea surface) till 0.95 (strong
reflection by fresh snow);
8. Input solar incident angles (degrees)
– It is recommended to input one or several values of the solar incident angle
(depending on the answer to question 2 in ranges: 0
(the Sun is in zenith) till
80
(the Sun is near the horizon).
Then the program accomplishes the calculation and output the result to the
screen and to the resulting file “eddaer.dat”, where are also input values of the
optical model
Table 12.1 The optical model of the clear atmosphere
l, mm 0.36
0.4
0.45
0.5
0.55
0.6
0.65
0.7
0.8
0.9
t as
0.379 0.316 0.285 0.264 0.250 0.237 0.224 0.213 0.201 0.190
t aa
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
t ms
0.564 0.364 0.223 0.145 0.098 0.072 0.052 0.039 0.023 0.014
t 0
0.983 0.720 0.552 0.449 0.388 0.349 0.316 0.292 0.264 0.244
o 0
0.959 0.944 0.927 0.911 0.897 0.885 0.873 0.863 0.849 0.836
g
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
126
12 Calculating Solar Irradiance with Eddington Method