It is known that the reflected component of solar ra-
diation B, :
Bo (9m, 9m) * Bx, 9 R nm Xo)X1« EL), (1)
where B(«,9) -sky brightness in the direction of + (zenith
angle) and ec (azimuth), R, -reflectivity of a surface
element of the wind-ruffled sea, fnm -angle between the
normal of wave surface element and the direction of incident beam,
Xo,X,... x, -parameters characterizing optical properties of the
sea surface under consideration.
Due to the dynamic character of the wind-ruffled sea,
the determination of the unique value of the radiation reflected
from a fixed surface element of water is quite out of question.
Unregularity of real waves necessitate to use the probability
functions to characterize the process of reflection from the
rough sea surface. The reflected component of upward radiance
is considered a weighted average,the probability of reflection
from a given solid angle being a weight ratio. The reflecting
wave surface is described by the probability law providing us
the distribution of the normals of wave surface elements. Hence,
we have :
db, = BH IR (Pam, Xe) X4 ++. M) P(«5,9,) do", ER
where det: ade. 5. = _wnddd da (3)
4 «O^ Dnm 4 con Sam
Here sun and S -correspondingly the azimuth and zenith
angle of the normal of wave surface element, P(«x,,9,) -the
function characterizing the probability of direction of this
normal, 2 Poss - angle between the direction of observation
(my Sm and the variable direction ( ot, 4 ), do -solid
angle of the sky surface element corresponding to the incident
radiance B («,$);-du* -solid angle for the direction
of normal («4,394 ) corresponding to the solid angle of incident
radiation dw .
An incident beam could be both the direct solar and sky
radiation. Hence,
B(«,8) » 5, («5,9») * B, («,3), (4)
where B,(æ,9) -brightness of the sky, Bo (4.9»)-brightness of the
visible Sun's disc, op and 9, -correspondingly the azimuth
and zenith angle of the centre of Sun’s disc. However, it’s better
to. use,not...Bes :+.but- the. value of direct. solar radiation flux onto
a horizontal. surface i. :E,.), which.data. is more. available.-As
it is known , approximately
B Fo ,
o wade 120 ) (5)
where do -solid angle of the visible Sun’s disc.
Taking into account the various directions of wave sur-
face normals, we obtain
an Vy
= sun $
8.2] PB, my ngs se he Pe EL aedi.
9 0 hws Yam
(6)
Ec (Pano? yp XL) Pldno Ina) 4
LG con So Oo“ Sumo
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