516
|
HUFF
POINT RELATIONS BETWEEN RADIOACTIVE RAINOUT
AND RAINFALL FACTORS
Data from the 1962 and 1963 networks were used to investigate the
relation between the concentration and the deposition of rainout of
radioactivity and the intensity, the duration, and the volume of rainfall
between network stations in convective storms. This point-to-point
Study was then extended to compare areal patterns of rainout and
rainfall. Gross beta data were used in the study.
Correlation analyses between rainout of gross beta and rainfall
factors are summarized in Table 5. These analyses indicate a general
trend for gross beta concentration to decrease with increasing rainfall
volume, duration, and intensity. Gross beta deposition shows a general
trend to increase with the three rainfall factors. The strongest correlation was found with storm-rainfall volume, as expected, since it
incorporates the influences of both duration and rate. Results similar
to those presented in Table 5 were obtained also from five 1962 storms
in which rainout of *’sr and "Sr was determined.
The correlation coefficients in Table 5 are not outstanding. For
example, the highest median coefficient of 0.70 between rainfall volume
and deposition indicates that only about 49% of the variance in beta
deposition is explained by the variation in storm-rainfall amounts.
Furthermore, in most of the various categories presented in Table 5,
the correlation coefficient had a wide range from positive to negative
values among the storms. For example, the correlation coefficient
between beta concentration and rainfall volume varied from 0.58 through
zero to —0.77 on the East Central Illinois network. However, the
deposition trend was much more stable since only one negative coefficient resulted from the correlations between rainfall volume and beta
deposition on the East Central Illinois network, and all coefficients
Table 5—- MEDIAN CORRELATION COEFFICIENTS BETWEEN
GROSS BETA ACTIVITY AND RAINFALL FACTORS
Network
Rainfall
Rainfall
Rainfall
Number
volume
duration
rate
of storms
Correlation with Beta Concentration
6000 Square miles
East Central Illinois
Boneyard— Kaskaskia
—0.39
-— 0.63
—0.36
—0,24
—0.40
—0.36
—0.29
—0.24
9
9
15
Correlation with Beta Deposition
6000 Square miles
0.70
0.31
Boneyard— Kaskaskia
0.56
0.38
East Central Hlinois
0.64
0.41
0.28
0.48
9
9
15