22
where C is a normalized constant satisfying ,J n(r)dr = 1 and r min - 0.02^m , r max = lO^m.
We show the theoretical reflectance curves against the viewing zenith angle in the principal
plane at the wavelengths of 0.85/^m and 0.45/^m for a two layer atmospheric model of mixed
atmosphere, consisting of aerosols and gaseous molecules, bounded by a rough sea surface layer.
The principal plane is a plane containing both the solar and the viewing directions. For the analysis
of the airborne POLDER data , the internal upwelling reflectance ji I h / at the flight altitude
of the aircraft ( h = 4700m) was computed in the principal plane by using the internal reflection
function R h , in stead of R at the top of the atmosphere.
We estimated the sea surface wind field by comparing the observed reflectance data with the
theoretical reflectance curves with different wind speeds and directions. The wind direction W d is
measured counter-clockwisely from the solar azimuth direction. The surface wind field was thus
estimated to be 9.0 m/s ^ V ^ 14.0 m/s and 215° ^ W d ^ 240° . The ranges of these estimated
wind field depend on the refractive index values of aerosol particles. Since the observed wind field
was V = 14.4m/sec and W d = 220° , the agreement between the estimated and observed wind
directions is very good. But there is a slight disagreement between the estimated and observed
wind speeds.
In the next we also show the results of the aerosol particle's optical parameter estimation at
0.85/mi in Fig. 1 and Fig.2, which are based on the log-normal size distribution cases and the
Junge type cases, respectively. In the computations we assumed the total aerosol optical thicknesses
of x = 0.120 at 0.85/mi and x = 0.314 at 0.45/^m, which correspond to the observed values [7]. The
possible ranges of the real part and imaginary part of refractive index are found to be ( n~1.50 and
k - 0.01) and ( 1.33 ^ n ^ 1.50, and 0 ^ k ^ 0.01) when we assume Junge's index of v = 3.5
and v = 4.0, respectively. In the case of the water-soluble aerosol model the refractive index of (n
~1.5, and k - 0.01 ) can satisfy the observed reflectance data barely. The cases of Junge model
