OL fe too + + t +%q F x + + + + lL x ° + 6 a r ° sf mo =5 aie zs y A of 2x A + 4 A oO 2 e 2 Oo “Olt L f 090i Rh'°2 CONCENTRATIONS ABOVE 194 km. © OP10°N © 40°-50°N A i0%20°N 9 50°—60°N 20°-30°N x 60°-70°N + 30°-40°N Stet ta | "JASON Dy MTT ASTON DE MAM IA ‘SOND )J FMAM JAS ONDjJ FF MAMY 1958 1959 1960 IS6I Fig. 1 -- Concentration as a function of time for different northern latitude regions