672
THATCHER, PAYNE, AND CAMERON
where D is the monthly deposition of "Sr in millicuries per square
kilometer (obtained from HASL lists), P is the monthly precipitation
in centimeters, and n is the number of months included.
At present this method of calculating tritium fallout may be checked
only against one measurement Series, that for Rio de Janeiro in 1962.
The calculated tritium-concentration average for 1962 is 25 T.U.
Measurements (average of six months) gave 36 T.U. Further study is
being given to the calculation of tritium-fallout concentrations from
data on particulate fallout.
COMPUTATION OF TRITIUM INVENTORY
Deposition of tritium over land and ocean was computed for 1963.
This with the data for 1962 and previous years permits estimation of
the remaining stratospheric inventory as of Jan. 1, 1964. Such a computation requires accurate values for the tritium concentration by
latitude bands in 1963 and similarly accurate values for the precipitation within the bands. The tritium distribution with latitude was obtained
by averaging data from oceanic stations and plotting the tritiumconcentration curves as shown in Fig. 13. Oceanic stations were used
6000
TTT
ne
FORT SMITH
EDMONTON
5000 -
TTT
A
VIENNA
4000 --
= 3000 b
REYKJAVIK
ADAK
Fig. 13—Northern-hemiSphere tritium-concentra-
Cc
.
2000 [-
tion curves used to establish total deposition.
FLAGSTAFF
Continental
1000 +
D
0
|
80°N
sites:
A,
spring; B, fall. Oceanic
ites: C, C, spring;
sites:
spring D, iefall.
MIDWAY
l
60°N
|
ENTEBBE
|
40°N
LATITUDE
4
20°N
0