430 GUDIKSEN ET AL. The samples were taken during routine training flights along the flight tracks shown in Fig. 2. Normally four samples, with a sampling time of 45 min for each, were taken during each flight, two above and two below the tropopause. The outside air temperature was monitored during each flight and utilized whenever possible as an indicator of the tropopause height. In-flight wind speeds were recorded from the air- craft’s radar bombing system, and a log of in-flight information was taken. Unfortunately, we were unable to collect sufficient CO, with this sampler to determine the “C content; however, we found that the Ascarite did serve as a filter medium for nuclear debris. TT )WHIDBEY u | SPOKANE ~ HOQUIAMU jo OLYMPIA 6 ) ASTORIA ® POR TLAND fo A PENDLETON 4 SALEM BAKER NORTH BEND) “~~ —_ 2 Sea, NBOISE/ —/ L CRESCENT CITY \RERA POINT ARENAS OS REGULAR FLIGHTS — — OCCASIONAL FLIGHTS SAN FRANCISCO Fig, 2—Air-sampling routes over the Pacific Northwest which are followed in the sampling program.