RELATIVE Sr CONCENTRATIONS IN SURFACE AIR
623
REPRODUCIBILITY AND SYMMETRY OF ANNUAL OSCILLATIONS
In the study of
ground-level air, as
the absolute activity
to site and between
relations sought. In
the seasonal variations of Sr concentrations in
in the precipitation studies, it has been seen that
levels are so variable between samples from site
the hemispheres as to obscure possibly the very
an attempt to better focus the data on these prob-
lems, the absolute “Sr air concentrations were normalized in the following way: (1) the average bimonthly concentration at each site was
computed by adding all the values for eachyear and dividing by six, and
(2) each bimonthly concentration value was then divided by the average
computed. By this method, each piece of data is relative to all other
data regardless of latitude, year, or absolute concentration, All the
values then become fractions of the annual average and thus tend to
distribute about unity. Use of this normalizing procedure tends to point
up the systematic fluctuations while damping the short-term effects.
Figure 6 illustrates the method. Here, all the data were reduced as
previously described and plotted against latitude for each bimonthly
period. It can be seen from this figure that the maximum spread of
values is from about two-tenths to three times the average.
It is quite clear that the two curves in each of the six bimonthly
periods follow similar trends. If the extensive atmospherictesting during 1962 compared to the complete absence of such testing in 1963 is
w
2h
JANUARY AND FEBRUARY
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|
|
wy
|
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JULY AND AUGUST
4
ob
+
-
{
|
h
4
q
1
|
“Ss
|
=
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—
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]
MARCH AND APRIL
L
|
L
L
/
SEPTEMBER AND OCTOBER
‘\
BIMONTHLY CONCENTRATIONS OF %5:/ AVERAGE
BIMONTHLY CONCENTRATION OF "sr
considered, these curves clearly illustrate the strong and reproducible
{
MAY AND JUNE
0
90°
,
70° 50°
N
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30°
|
10°
NOVEMBER AND
DECEMBER
i
10°
!
30°
|
ie tae
50° 70° 90° 70° 50° 30 10°
5
i
10°
N
LATITUDE
Fig. 6—Relative *Sr concentrations in tropospheric air along the 80th
meridian.
, 4962 NRL data; ———, 1963 HASL data.