PEM-Tropics A

The two major objectives of PEM-Tropics are:

1. To provide baseline data over the Basin for gases important in controlling the oxidizing power of the atmosphere including ozone, H₂O, NO, CO, and NMHC's;
2. To understand the factors controlling the concentrations of these gases, and to assess the resulting sensitivity of the oxidizing power of the atmosphere to anthropogenic and natural perturbations.

In addition, PEM-Tropics has three secondary objectives:

1. To survey the concentrations of aerosol precursors and ultra fine aerosol particles over the South Pacific Basin;
2. To improve our understanding of sulfur gas-to-particle formation over the region;
3. To provide detailed latitude-altitude transects of long-lived gases for the evaluation of global tropospheric models.

PEM-Tropics employed the NASA DC-8 based at NASA's Ames Research Center, Moffett Field, CA, and P-3B aircraft based at the NASA Wallops Flight Facility, Wallops, VA. The two aircraft covered an area extending zonally across the entire Pacific Basin and meridionally from Hawaii to south of New Zealand. Together they provided significant coverage of the Walker circulation cell over the Pacific Basin including the upwelling region over the western equatorial Pacific, the subsiding region offshore of South America, and the connecting atmosphere in between.