RELATIVE “Sr CONCENTRATIONS IN SURFACE AIR 3 AUGUST AND SEPTEMBER SEPTEMBER AND OCTOBER aL_ FEBRUARY AND MARCH MARCH AND APRIL | Sok 7 7 _I iE 0 = | 3 2 {~ i | i =o OCTOBER AND NOVEMBER NOVEMBER AND DECEMBER — pe Toe 3 | { ! PE OTD ae | | os Ley ! | ! | 40°N L 30°N LL JUNE AND JULY JULY AND AUGUST | be 7 4 Pe a _ — 0 60°N | — | TT ~T | =m 4 i DECEMBER AND JANUARY JANUARY AND FEBRUARY 2 = APRIL AND MAY MAY AND JUNE = 0 L_ -=— 627 ! | 20°N-_—sICPN 0 60°N LATITUDE _L 40°N | 30°N) - — | L 20°N-OPN 0 _ee Fig. 9—Relative Sr concentrations in precipitation and tropospheric aty in the northern hemisphere. ———, average bimonthly precipitation vs. bimonthly precipitation (1962-1963 HASL pot and column network); , average bimonthly ?Sr concentration vs. bimonthly *Sr concen- tration {1962—1963 80th meridian (west) network]. The relative rainfall values were plotted as the reciprocal in this graph to make the correlation easier to See. It is certainly very clear that inthefirst two periods when no highs in air concentration occurred an inverse proportional relation exists. In the subsequent periods, although the relation is not quite as simple, a general dependence of air concentration upon precipitation is exhibited. For example, at the highest northern-hemisphere peak time (March and April), it would appear thatthe relative high at low latitudes must be due in part to the relatively low rainfall in the immediately preceding time period. Conversely, in the middle latitudes at that time, the much lower relative “Sr values correlate with higher precipitation. Undoubtedly, this effect cannot completely explain the bimonthly profiles of air concentrations, but it does appear to influence the data to a measurable degree. It is felt that major meteorological airtransport mechanisms determine the broad patterns and timing of

Select target paragraph3