During July 1977, NASA Ames Research Center, together with a group of university and government research scientists, conducted a field program to study the mechanisms and scales of tropospheric-stratospheric exchange. The program was conducted in the Panama Canal Zone during the passage of the Intertropical Convergence. Two aircraft, operating from Howard Air Force Base, carried instruments to measure ozone, nitric oxide, nitrous oxide, halocarbons, methane water vapor, aerosols, temperature, and pressure. A Learjet was used for tropospheric measurements, and a U-2 was used for measurements through the trop-opause and into the stratosphere to an altitude of 21.3 km. Special ozone and rawinsondes were flown four times daily from Fort Sherman during the 16-day experiment, and meteorological rock soundings were made daily during the month of July. Special satellite cloud photographs were also taken during the experiment.