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Fig. 5.1.
The ratio of the irradiance variation to the SD (“signal-to-noise”) when comparing
the calculations with different degree of the accounting of the molecular absorption.
Lower
curve:
five gases (O
3
,H
2
O, NO
2
,O
2
,NO
3
) are taken into account comparing with all
atmospheric gases;
upper curve
-accountingofallatmosphericgasescomparingwiththe
case of the neglecting of molecular absorption;
solid line
corresponds to the minimal SD of
the measured irradiance,
dashed line
corresponds to the SD equal to 1%.
Thick lines
mark
the complete intervals of the molecular absorption
particular, heterogeneous) cause not only decomposition of NO
3
,butalsoits
generation in daytime (Rudich et al. 1998). The existence of NO
3
in daytime
atmosphere is confirmed with the observations of its content with
the method
of the spectral transparency
(Weaver et al. 1996). At last, the NO
3
absorption
band has been directly revealed in the spectral behavior of transmittance in
the clear sky (Vasilyev O et al. 1995).
The same estimation of the signal/noise ratio (SNR) should be used for se-
lection of the concrete spectral intervals. The selected intervals are presented in
Table 5.1. It should be noted that in spite of the traditional conceptions there is
no spectral interval within the VD region, where neglecting the molecular ab-
sorption is possible apriori, if the accuracyof the observations or calculations is
about 1% (Ivlev and Vasilyev A 1998). Remember that the mentioned selection
of the gases and wavelengths intervals has been accomplished after carrying
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