505
RESULTS
its
Application of the above method gives reasonable approximation to the shape
of the haze size distribution function with some reservations to be discussed later
e
PHX
However, it was observed that some over compensation for high values in the small
radii size classes appeared as negative values in the larger sizes. This problem
was remedied by observing that no change in the law of scattering for a haze is
i .008
: -.005
-.021
: -.01
> -.006
made by multiplying the size distribution by a scalar. This observation follows
from the definition of the extinction coefficient and the phase function (Van de
Hulst, 1957). Thus the differences between the solution obtained and the "true"
solution should be no more than a constant factor.
All values of the solution which were negative were set to zero and extinction
coefficients were computed using this "trial” solution. The mean of the ratios
) .009
of the observed extinction coefficients to those computed from the "trial" solution
was computed. That is,
o> 00 LO ^ H ^
o o o o o o
o o o o o o
1 1
, M 3 .(A.)
1 . „ obs K .
L ~ M . , 8(A.)
1 = 1 1
The "trial solution was again modified by multiplying by C, that is N(r) = CN t (r),
N t (r) being the "trial" solution.
Table 2 displays the results of this operation for the three sites. Table 1
gives a tabulation of the extinction coefficients computed from the site distri
butions. Estimates of the extinction coefficient for the three sites appear to
be best when the wavelenth is in the interval of the data wavelength values.
)
LO 4
LO 4
LO 3
L0 2
REFERENCES
Phillips, D. L.
1962: A Technique for the Numerical Solution of Certain Integral Equations
of the First Kind. J. Ass. Comp. Mach., 9, p. 84.
Twomey, S.
1963: On the Numerical Solution of the Fredholm Integral Equation of the
First Kind. J. Ass. Comp. Mach., 10, p. 97.
Van de Hulst, H. C.
1957: Light Scattering by Small Particles. Wiley and Sons Inc., New York.
10‘ 2
Yamamoto, G. and Tanaka, M.
1969: Determination of Aerosol Size Distribution from Spectral Attenuation
Measurements. Applied Optics, 8, p. 447.
