Geoscience Reference
In-Depth Information
The geometry for pixel was the following: the point remained within the
POLDER field while the satellite passed over it. As the satellite passed over
a target, from 6 up to 14 directional radiance measurements (for each spec-
tral band) were performed aiming at the point. Therefore, POLDER succes-
sive observations allowed the measurement of the multidirectional reflectance
properties of any target within the instrument swath.
Three wavelength channels with the centers at 443, 670 and 865 nm were
available for our analysis. The radiance multidirectional data were given in
units of the normalized radiance, i. e. the maximum spectral radiance divided
by the solar spectral irradiance at nadir and multiplied by
µ
0
was
the cosine of the solar incident angle. The solar angle, azimuth angle, viewing
directions and cloud amount were also included to the data array. The date
of the observations under interpretation was 24 June 1997. Seven sites with
extended cloud fields were chosen.
The information about the satellite images used for the optical parameters
retrieval hereinafter are shown in Table 3.4. The values of the single scattering
albedo and the optical thickness typical for most of the pixels of the image are
presented in columns number eight and nine of the table. We should mention
that images 14 and 15 demonstrate the same cloud field, as do images 16-18.
πµ
0
,where
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