Remote-Sensing Technologies and Data Processing Algorithms - New Ecoinformatics Tools in Environmental Science: Applications and Decision-making - page 182

Fig. 2.31 Empirical
dependence of brightness
temperature sensitivity on the
wind speed when the
observation is realized by the
nadir (Sasaki et al. 1988)

arbitrary wind speed: c P ðhÞ ¼ c OP ðhÞ (V/T S Î ) @ T BP ðhÞ=@ V, where T SO is the sea

surface temperature, ʳ P and ʳ OP are the re fl ectivity of the roughned and the calm sea

surface, respectively.
According to Sasaki et al. (1987a, b, 1988) the wind speed sensitivity of the sea
surface brightness temperature at satellite level is

n o

T # sky
B

ðhÞþ T space
B

T SO

@

T sat

BP ðhÞ
@ V ¼ @

T BP ðhÞ
@

;

V T SO

where T # sky
B

is the downward sky brightness temperature at sea surface (K), T space
B

is

the galactic noice (K).
The sea surface brightness temperature at arbitrary wavelength can be repre-
sented in the form:

T BP ðhÞ ¼ e 1P ðhÞ T SO þ c P ðhÞ T k; sky ðh S ; / S Þ;

B

where ʸ S and ˕ S are the zenith and azimuthal angles,

Z

2 p

Z p= 2

1
4

c P ðhÞ ¼ c P ðh; h S ; / S Þ sin h S d h S d / S :

p

0 0

Under conditions of wind-induced sea roughness, when sea wave are so big that
radio waves of the centimeter and decimeter ranges cannot be used, scattering and
emission characteristics can be estimated by means of Kirchoff s approximation.

In the range of centimetre waves, where electrophysical properties of water are
comparatively known, the expression ( 2.7 ) allows to determine water surface
temperature when its radiothermal emission is measured.
In common case the task of ocean surface diagnosis comes to the reverse of
function T j = F(a 1 ,

'

… , a k ) in the relation of geophysical parameters set {a i }. The

function F re fl ects the type of aquatory radiation model. Linear models allowing to