308
FEELY AND BAZAN
Monthly mean *Sr concentrations at 65,000 ft at a series of
latitudes are shown in Figs. 5 and 6. Maximumsoccurred in the con-
centration curve for 45°N (Fig. 5) in October 1961, with the first
interception of fresh debris from the 1961 U.S.S.R. tests, and in early
1963, following the 1962 U.S.S.R. test series. At 65°N (Fig. 5) maxi-
mums occurred in the concentration curve in June 1962, with the delayed arrival in the Star Dust sampling corridor of debris from the
high-yield 1961 U.S.S.R. events, and in January 1963, following the
1962 U.S.S.R. test series. At 10°N (Figs. 5 and 6) maximums occurred
in the concentration curve in July 1962, with the interception of fresh
debris from the 1962 United States Operation Dominic I tests and in
mid-1963, probably as a result of equatorward (and upward) movement
of debris from the lower northern polar stratosphere. Maximums occutred in the concentration curve for 10°S (Fig. 6) in September 1962,
with the interception of fresh debris from Dominic I shots, and in
September to November 1963, when debris moving southward from the
northern hemisphere was sampled. This southward-moving debris was
also sampled at 35°S in late 1963 (Fig. 6), and a maximum in the concentration curve was noted.
These data obtained by means of WU-2 aircraft sampling during
Project Star Dust appear to be consistent with the conclusions reached
above based on data obtained from balloon sampling.
sr ACTIVITY, DIS/MIN PER 1000 SCF
VP TTT TTT TTT TTT TTT
65,000 FT
@ 65° N
0 45° N
Alf? N
birtittipetpipi tir tapi p ip ti titi i tei
JJASONDJFMAMJ JASONDJFMAMJJASONDJFMAMJ JASOND
1961
1962
1963
1964
Fig. 5—Trends in Sr activity.