NASA GTE TRACE A experiment (September–October 1992): Overview

Abstract

An overview of the Transport and Atmospheric Chemistry near the Equator‐Atlantic (TRACE A) field mission is presented. TRACE A was conducted to provide a comprehensive investigation of the chemical composition, transport, and chemistry of the atmosphere over the tropical South Atlantic Ocean and the adjacent South American and African continents. Measurements for TRACE A consisted of a remote sensing component to derive tropospheric ozone and biomass burning patterns, an airborne atmospheric chemistry component to determine the composition of the air in the most pristine areas of our research domain as well as to characterize the photochemistry and transport of trace gas emissions from both fire and biogenic sources, a series of ozonesonde observations, and an enhanced radiosonde network and airborne meteorological measurements that provided information about the transport of trace gases and the physical processes that were responsible for their observed distributions. The data were interpreted through the use of both photochemical and meteorological numerical models. The picture that emerges from TRACE A is that widespread biomass burning in both South America and southern Africa is the dominant source of the precursor gases necessary for the formation of the huge amounts of ozone over the South Atlantic Ocean. In addition, however, the meteorology in this region of the world is favorable for the accumulation of these pollutants over the tropical Atlantic basin so that photochemical processes produce large quantities of ozone in situ. The generation of ozone occurs over scales of thousands of kilometers and is unusually enhanced in the upper troposphere where relatively high concentrations of nitrogen oxides (NOx) prevail. This latter finding suggests that convective processes (or other lifting mechanisms) may play an important role in the generation of tropospheric ozone or that there may be an additional significant upper tropospheric source of NOx, such as from lightning.

Analysis of a Regional Scale Chemical-Transport Model to Investigate the Potential Capability of Satellites for Identifying a Widespread Air Pollution Event

“…The enhancements found within the TOMS elevated integrated amounts over Brazil were consistent with the in situ aircraft profiles measured in a NCAR field campaign measured in 1980 (Crutzen et al, 1985). Subsequent measurements from the TRACE-A field campaign (Fishman et al, 1996a; using ozonesonde, in situ, aircraft remotely sensed, and satellite measurements confirmed that enhancements in the TOMS total ozone signal were a result of widespread biomass burning over Brazil and southern Africa (Fishman et al, 1990), which, because of the low-level transport from the east and the upper-level transport from the west, highest TOR amounts were found over the south Atlantic Ocean.…”

Spatial and temporal variability in the ratio of trace gases emitted from biomass burning

“…In the beginning of the 1990s, the experiments of these individual groups were followed by a number of large international biomass burning experiments in various ecosystems throughout the world. These included the Southern Africa Fire-Atmosphere Research Initiative (SAFARI 92 and SAFARI 2000) in southern Africa (Lindesay et al, 1996;Swap et al, 2002), Dynamique et Chimie Atmosphérique en Forêt Equatoriale-Fire of Savannas (DECAFE-FOS) in West Africa (Lacaux et al, 1995), Transport and Atmospheric Chemistry Near the Equator-Atlantic (Trace-A) over Brazil, southern Africa, and the South Atlantic (Fishman et al, 1996), Fire Research Campaign Asia-North (FireS-CAN) in central Siberia (FIRESCAN Science Team, 1996), and Smoke, Clouds, and Radiation-Brazil (SCAR-B) in Brazil (Kaufman et al, 1998).…”

Dependence of solar radiative forcing of forest fire aerosol on ageing and state of mixture

“…The Southern Tropical Atlantic Region Experiment (STARE, Andreae et al, 1996), encompassing the Transport and Atmospheric Chemistry near the Equator -Atlantic (TRACE A, Fishman et al, 1996) experiment which conducted measurements in plumes from biomass-burning over Brazil, the Southern Atlantic, and Southern Africa, and the Southern African Fire -Atmosphere Research Initiative (SAFARI-92, Lindesay et al, 1996), focussing on the Southern African source regions, reported detailed size distributions of the particles in plumes measured using airborne insitu instruments while the project was focused on ozone producing gas phase chemistry. The Smoke, Clouds, and Radiation -California (SCAR-C, Kaufman et al, 1996) project and the Boreal Ecosystem-Atmosphere Study (BOREAS, Sellers et al, 1997) are of the few experiments to provide information on aerosol produced by forest fires in temperate regions of the globe.…”