490 LOCKHART, PATTERSON, SAUNDERS, AND BLACK T— JANUARY—FEBRUARY 1962 a U.S.5.R. 1961 DEBRIS 107 = — }-— / / a ™ ~ = —— 6 ook < ~ ™ a” a“ yo 5 103 }— = s / A \ PRE-1961 DEBRIS AY \ \ \ \ \ \ a \ \\ x oO ‘ N * \A ‘N a. 3 g = 10-4 —— 80°N | 60°N L 40°N . L 20°N | O° 20°S | 40°S 60°S LATITUDE Fig. 9—Pyrofiles of the °Sr concentrations in January and February 1962 in the air along the 80th meridian (west). monthly periods January and February, May and June, and November and December as functions of the nuclear-test series serving as the sources, In the January and February period (Fig. 9), the old pre-1961 debris was of equivalent concentration in the two hemispheres and showed the expected distribution with midlatitudinal maximumsand an equatorial minimum. The fresh debris from the U.S.S.R. 1961 tests

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