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44
RAINFALL, IN.
Fig. 3d— Regression of sr™ in rain water on the amountof rainfall collected March through
July 1956 at Mobile, Lake Charles, Jackson, and Little Rock.
From these plots it is obvious that activity is proportional to the amount of rainfall within
each area. Correlation coefficients for all graphs are summarized in Table 4.
Table 4—CORRELATION COEFFICIENTS FOR THE REGRESSION
OF Sr®® ON INCHES OF RAINFALL
Time of sampling
Fraction of total
sampling area
March
Total sampling area
Above 40° latitude
Below 40° latitude
Northeast
Northwest
Southeast
July
March—
July
0.31
0.47
0.60
0.37
0.42
0.43
0.66
0.37
0.72
0.77
0.78
0.77
April
May
June
0.77
0.57
0.86
0.46
0.45
0.63
0.95
0.87
0.90
Southwest
eyes
0.87
The next step in the analysis of the rain water data is made by comparing Sr*® in rain to
that measured by various pot type collectors. However, most of these devices collect total
fallout and have sampling networks that do not coincide with the rain water stations. Therefore, a comparison of these results can only indicate the relative levels of rainout to total
fallout. This comparison is shown in Table 5 in which the average values of fallout in rain
Table 5— COMPARISON OF FALLOUT (MC/SQ MILE/MONTH) IN RAIN
WATER TO TOTAL FALLOUT®
Alr Force
rain water
Average
Sampling
month
New York
New Haven
roof pots
dustfall
total 8
Average
Total 8
activity
sr”
activity
sr*®
Total B
activity
Sr?
Srin
Pittsburgh
rainfall
March
20
1.3
46
1.9
April
May
45
21
1.3
1.2
83
71
0.8
1.0
63
42
2.3
0.6
1.0
1.5
June
July
17
27
0.8
1.5
27
77
0.8
0.6
28
0.6
1.4
0.6
351
1.3