Twilight lithium

Mechanisms and rates of transport of nuclear test debris in the upper and lower atmosphere are considered. For the lower thermosphere vertical eddy diffusion coefficients of 3-6 X 106 cm.2 sec. 1 are estimated from twilight lithium enhancement observations. Radiochemical evidence for samples from 23 to 37 km. altitude at 31° N indicate pole-ward mean motion in this layer. Large increases in stratospheric debris in the southern hemisphere in 1963 and 1964 are attributed to debris from Soviet tests, transported via the mesosphere and the Antarctic stratosphere. Most of the carbon-14 remains behind in the Arctic stratosphere. 210Bi/ 210Pb ratios indicate aerosol residence times of only a few days at tropospheric levels and only several weeks in the lower stratosphere. Implications for the inventory and distribution of radioactive fallout are discussed. 

Figure 2. Variations in twilight lithium abundance at 80 km. altitude following the Teak and Starfish rocket explosions (16)...

Figure 3. Twilight lithium enhancements at Saskatoon during the Soviet thermonuclear tests of Sept. I-Noo. 4,1961 (37)...

---