JANUARY 2001: Biomass burning pollution over the South Pacific

Genesis of a large biomass burning pollution plume observed on September 18, 1996 between Fiji and New Zealand during the NASA PEM-Tropics A aircraft mission over the South Pacific. Ozone concentrations as high as 140 ppbv and CO concentrations as high as 160 ppbv were observed in that plume. The figure shows the evoluti on of the CO free tropospheric column from September 9 to September 18 simulated by Amanda Staudt using a global 3-D chemical tracer model driven by assimilated meteorological data from ECMWF reanalyzed by T.N. Krishnamurti's group at Florida State University. Winds and pressure centers are also shown. September is the end of the dry season in the austral tropics, and considerable biomass burning takes place during that time in southern Africa and Brazil. The resulting biomass burning pollution accumulates over the South Atlantic, as demonstrated previously in the NASA TRACE-A aircraft mission, and is channeled to the Indian ocean by low-pressure systems at southern mid-latitudes. In the days leading to the September 18 event, extension of the low pressur e band from southern Africa to Australia resulted in unusually fast transport of the biomass burning pollution to the South Pacific. Although the September 18 event was particularly dramatic, the PEM-Tropics A mission observed considerable biomass burning pollution throughout the South Pacific atmosphere, demonstrating that the influence of this pollution extends to the most remote reaches of the tropics. Details on why and how are presented by Staudt et al. [2001].