CADMIUM-109 RESULTS FOR UP TO 20 KM 407 Wg OT TTT TTT TT © 30TO 75° N H @ 0TO30°N | es oO = s —_ 4 4 070 30° S S109 He = A 4 30TO 50° S$ o a 4 pe 5 Ww a 107 -l bH O 4 .{ 24 a O @) 4 ey =2 =4 1 r A ? — as & 4 2 4 0 B 9 oO Po Ste) O 4 O° ° O° & O ee — = = = Oo 88 o 4 QO i _ - oO H ~ s — S 4 —_ oO xa — _ e e a; Qa. r — Z = r ~ = o 5 1077 He os& Ff e = =a a ? 4 = :— = 10-4 Litt tlL ype pyeEyrTE tyr |p ypyteTipyrtiiil JASONDIJEMAMJJASONDIJ FMAMJJASOND 1962 1963 1964 Fig. 1—Cadmium-109 concentrations above 19.2 km. DISCUSSION The first appreciable rise in !°°Cd concentrations did not occur until the beginning of the southern-hemisphere spring of 1963 with concentrations reaching a maximum value at the end of Novemberat high latitudes in the southern hemisphere, This is approximately three months later than the corresponding observations for the increase of 1022Rh in the northern hemisphere during the winter of 1959-1960. This is consistent with the difference in timing between hemispheres for the major winter disturbances in the polar vortex region.’ Concentra- tions in the southern hemisphere dropped off markedly after November. This decrease suggests that perhaps the November samples (44 and 48°S) represented a hot spot. The northern-hemisphere winter of 1963-1964 has been characterized as being quite mild in terms ofdisturbances in the polar region,