The TRACE-A study was deployed in September-October 1992 to determine the cause and source of high concentrations of ozone that had been discovered several years earlier over the tropical Atlantic ocean between southern Africa and South America. The large pool of ozone is a seasonal phenomena with the highest concentration of ozone occurring during the southern hemispheric summer months of August through October. The day-to-day vaiability in the ozone is illustrated in this figure. Ozone sonde data from launches at Natal, Brazil had provided earlier evidence of the seasonal variation in ozone but not its massive extent.

As prelude to the field deployment of TRACE-A, coordinated ozone sonde launches were initiated in August 1990 from Natal, Brazil, Ascension Island, and Brazzaville, Congo. These data, along with the additional ozone and rawind sonde stations that were either activated or enhanced during the deployment period, provided additional confirmation of the seasonal increase in ozone throughout the tropical Atlantic region. Results from the sonde network has also contributed to an assessment of the sources of the precursors of the ozone.

The Brazilian space agency, INPE, collaborated in all phases of the TRACE-A mission, and provided measurements prior to and after the DC-8 flights in Brazil. An extensive rawind sonde and ozone sonde network was established by the Brazilian scientists and coordinated flights were conducted by an instrumented INPE aircraft and the DC-8 aircraft.

In Africa, another major field experiment was being conducted. The Southern African Fire-Atmospheric Research Initiative (SAFARI) was investigating the ecological and atmospheric effects of wide spread vegetation burning in southern Africa. As part of SAFARI, controlled burns were conducted with ground based and airborne instruments to characterize the emissions on scales from less that 1 kilometer to hundreds of kilometers. The combined TRACE-A and SAFARI experiment comprised the South Tropical Atlantic Regional Experiment (STARE), a program sponsored by the International Global Atmospheric Chemistry Project.