Aerosol Characteristics in the Northern Territory of Australia During the Dry Season With an Emphasis on Biomass Burning

摘要

Results are presented on the atmospheric aerosol derived from aircraft measurements in the vicinity of Jabiru in Kakadu National Park during June and September 2003. The focus of the measurements was on the biomass burning aerosol (smoke) which is ubiquitous throughout the Northern Australian dry season (June - October). Data were also obtained on the coarse mode aerosol which is composed mainly of sea salt and soil. A comprehensive characterization was made of the aerosol microphysics, chemistry and optical properties. Additional ground based measurements were made at Jabiru to more fully characterize the chemistry of the boundary layer aerosol. A range of instrumentation was used including particle sizing instruments mounted inside the aircraft and two external aerosol spectrometer probes which were used to measure the aerosol number size distribution. Additional instrumentation included a filter-sampler to collect particles for chemical analysis, a nephelometer to measure the aerosol scattering coefficient, an absorption photometer to measure the absorption coefficient and various meteorological sensors. Results show clear differences between the beginning and the end of the dry season most notably in terms of smoke concentration aloft and the relative abundance of fresh and aged smoke. The vertical aerosol profiles changed markedly between months primarily due to the difference in mixing depth.