792
ROSER AND CULLEN
tions discussed in the literature in the past year: the spring maximum,
the ocean—continent effect, and the correlation between filter ‘and
column data.
Brazil with its wide latitude spread offers an excellent opportunity
to observe the emerging but weak spring-maximumeffect in the southern hemisphere. The 10 stations at which measurements were made in
this study encompass a range from the equator to approximately 30°S;
they are given in Table 1.
Table 1—BRAZILIAN FALLOUT-COLLECTION STATIONS
Station
Belém
Latitude
1°27°W
Manaus
Recife
Brasilia
Trindade Island
Nova Friburgo
Rio de Janeiro
3°02’S8
8°06’8
15°52’S
20°31'S
22°17'S
22°54'S
Sido José dos Campos
23°13’8
Itaici
,
520 Leopoldo
23°06'S
29°45'S
Longitude
48°29°W
Altitude,
ft
25
60°01’W
34°58°W
47°S6’W
29°20°W
42°32°W
43°13’W
95
10
3450
120
2800
100
45°51’W
2109
47°11 W
51°11'W
2190
115
Methodof
collection
Column
Pot
Pot
Column
Pot
Column
Pot
Pot
Pot
Pot
The average deposition rates of Sr at the stations are given in
Fig.
1
in histogram form, and precipitation data are also presented
where the data are reliable. No graph is given for the Recife station
Since service from there has been irregular.
The equatorial stations of Belém and Manaus do not have a four-
season cycle but a rainy and a relatively dry season. Here the spring
maximum would have no meaning. The fallout curve simply follows the
precipitation curve. These stations are sensitive to trophospheric fallout from the Sahara tests. In an irregular way they also show data
more typical of northern stations after northern tests, as, for ex-
ample, the Belém results for April 1962 (5.64 mc/square mile) and
February 1964 (2.43 mc/square mile). The interhemispheric equatorial
front moves southward during the northern summer; therefore these
stations are essentially in the northern troposphere for five months of
the year. The front shift, however, would probably not be an efficient
transport mechanism in view of the general minimal conditions near
the equator.
Sufficient precipitation data for Trindade and Brasilia are not at
hand; therefore a meaningful average curve cannot be presented. The
available data do indicate, however, that no spring maximum exists
and that precipitation is the strongest influencing factor. (See Fig. 2.)
Fallout for Nova Friburgo follows the rainfall curve. In Rio de Janeiro,