Geoscience Reference
In-Depth Information
Fig. 1.3.
Spectral extraterrestrial solar flux according to Makarova et al. (1991)
No real function can have such a property, thus the delta function is just
a symbolic record. Roughly speaking it does not exist without the integrals.
Basing on (1.10) in the case of the parallel beam it could be said that the
irradiance incoming to the perpendicular surface is numerically equal to the
radiance, however this equality is truly formal because the radiance and the
irradiance have different dimensions [that's all right withdimensions in (1.10)].
In conclusion consider the theoretical aspects of the procedures of radiance
and irradiancemeasurements. It is radiation energy that influences the register
element of an instrument. It could be written as:
λ
t
2
2
=
λ
E
dt
d
dxdy
t
1
λ
S
1
ϑ
ϑ
ϕ
ϑ
ϕ
,
t
)
f
i
(
t
)
f
λ
λ
)
f
S
(
x
,
y
)
f
Ω
ϑ
ϕ
×
sin
d
d
I
(
x
,
y
,
,
(
(
,
),
λ
Ω
ϑ
ϕ
where
I
,
t
) is the radiance incoming to the point of the input ele-
ment (input slit) of an instrument with coordinates (
x
,
y
); [
t
1
,
t
2
]isthetime
interval of the input signal registration; [
(
x
,
y
,
,
λ
λ
1
,
λ
2
]istheregistrationwavelength
interval;
f
t
(
t
),
f
λ
λ
),
f
S
(
x
,
y
),
f
Ω
ϑ
ϕ
)arethe
instrumental functions
,which
characterize a signal transformation by the instrument and they depend on
time
t
,wavelength
(
(
,
λ
, input element point (
x
,
y
), and direction of incoming ra-
ϑ
ϕ
diation (
) correspondingly. The integration over the area
S
is accomplished
over the instrument input element surface, and the integration over the solid
,
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