100,000 = whe 90,000 e > 346 —_@— a > —__—_@——___—_ . 58 80,000f- 70,000 Oo © 258 OY 60,000 eo 6 — 337 Bo tte ng 50,000 ¢ Oo Oo Oo ———_}—_— 40,000 300 | 305 310 3I5 | 320 325 COs ABUNDANCE, ppm. Fig. 8 -- Carbon dioxide gradient measurements attempted in the upper atmosphere