Analysis of Radiative Observations in Cloudy Atmosphere - Short-Wave Solar Radiation in the Earth's Atmosphere - page 239

7.1.4
Analysis of the Results of Observations in the High Latitudes
The observations were accomplished above the Kara Sea at latitude 75 ◦ N
(experiment No. 8: 1st October 1972, experiment No. 9: 29th May 1976 and
experiment No. 10: 30th May 1976). The altitudes of the cloud bottom and top
were 0.6-1.1 km in experiment 8, 5.0-8.0 km in experiment 9, 5.0-7.5 km and
8.0-9.0 km for two-layer cloudiness in experiment 10, considered as a whole
layer. The spectral optical parameters are shown in Figs. 7.1d and 7.2d. The
value of single scattering co-albedo (1 − ω 0 ) retrieved from the data of exper-

iment 10 demonstrates the conservative scattering within wavelength interval
0.45-0.67 ω 0 ∼ 0.06)

is caused by the source of the high pollution that has been situated at the lee
side of the observational site.

µ m. The high absorption obtained fromexperiment 8 (1−

7.2
Vertical Profile of Spectral Optical Parameters of Stratus Clouds
Theretrievaloftheverticalstructureofstratuscloudsisofinterestforinvesti-
gation of either the physical properties of the cloud or the study of distribution
of pollution within clouds (Feigelson 1981; Marchuk et al. 1986; Kondratyev
1991). Hereinbefore the spectral dependence of volume scattering and absorp-
tion coefficients has been obtained for the cloud layer, considered as a whole. If
the data of the airborne radiative measurements are available at several levels
within the cloud, it is possible to derive the vertical structure of the cloud opti-
cal parameters. As has been discussed in Chap. 6, while studying the scattered
radiation field inside the cloud, it is necessary to distinguish two essentially
different cases: (1) a single optically thick cloud layer with the optical proper-
ties, which vary in vertical direction; and (2) cloud system consisting of several
cloud layers separated by clear atmosphere.
The airborne radiative observations suitable for these two cases have been
described in Sect. 3.4 (experiments 6 and 7). During these observations the
spectral irradiance was measured at several levels within the cloud and at
the cloud boundaries. The observational results provide the input data of the
optical parameters retrieval.
The conditions of the experiments were the following:
Experiment 6. The measurements were carried out at five levels of the
double-layer cloud: above the upper cloud layer at altitude z = 4.1 km,within

= the upper cloud at altitude z 3 km, between the cloud layers at altitude

= = z 1.6 km, within the lower cloud at altitude z 0.6 km and under the lower

= cloud at altitude z 0.05 km;

Experiment 7. The measurements were carried out at six levels of the single-
layer cloud: above the cloud top, within the cloud and under the cloud bottom
at altitudes: 1.4, 1.3, 1.2, 1.1, 0.95 and 0.8 km (Table A.3 of Appendix A and
Fig. 3.13).
The spectral range of experiment 6 is 0.45-0.85 µ m, the data set contains only

41 wavelength points processed by hand; the spectral range in experiment 7