Characteristics and influence of biosmoke on the fine‐particle ionic composition measured in Asian outflow during the Transport and Chemical Evolution Over the Pacific (TRACE‐P) experiment

Abstract

[1] We investigate the sources, prevalence, and fine-particle inorganic composition of biosmoke over the western Pacific Ocean between 24 February and 10 April 2001. The analysis is based on highly time-resolved airborne measurements of gaseous and fineparticle inorganic chemical composition made during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) experiment. At latitudes below approximately 25°N, relatively pure biomass burning plumes of enhanced fine-particle potassium, nitrate, ammonium, light-absorbing aerosols, and CO concentrations were observed in plumes that back trajectories and satellite fire map data suggest originated from biomass burning in southeast Asia. Fine-particle water-soluble potassium (K + ) is confirmed to be a unique biosmoke tracer, and its prevalence throughout the experiment indicates that approximately 20% of the TRACE-P Asian outflow plumes were influenced, to some extent, by biomass or biofuel burning emissions. At latitudes above 25°N, highly mixed urban/industrial and biosmoke plumes, indicated by SO 4 2À and K + , were observed in 5 out of 53 plumes. Most plumes were found in the Yellow Sea and generally were associated with much higher fine-particle loadings than plumes lacking a biosmoke influence. The air mass back trajectories of these mixed plumes generally pass through the latitude range of between 34°and 40°N on the eastern China coast, a region that includes the large urban centers of Beijing and Tianjin. A lack of biomass burning emissions based on fire maps and high correlations between K + and pollution tracers (e.g., SO 4 2À ) suggest biofuel sources. Ratios of fine-particle potassium to sulfate are used to provide an estimate of relative contributions of biosmoke emissions to the mixed Asian plumes. The ratio is highly correlated with fine-particle volume (r 2 = 0.85) and predicts that for the most polluted plume encounter in TRACE-P, approximately 60% of the plume is associated with biosmoke emissions. On average, biosmoke contributes approximately 35-40% to the measured fine inorganic aerosol mass in the mixed TRACE-P plumes intercepted north of 25°N latitude.

An Investigation into the Ionic Chemical Composition and Mixing State of Biomass Burning Particles Recorded During TRACE-P P3B Flight#10

“…The BB plume was observed at altitudes ranging from the inversion to ∼3.5 km (vertical profiles of species concentrations and temperature variation can be found in Figure 3 of Ma et al, 2003). Figure 1 shows the 5-day back trajectories for these air masses (they can also be found at http://bertha.met.fsu.edu/∼tracep/).…”

“…Black Carbon emissions in Figure 1 are estimated based on satellite fire map observations, (see Ma et al, (2003) for more details). The plumes were composed of high concentrations of fine-mode particulate K + , light absorbing particles (e.g., black carbon), and gases often associated with biomass burning, such as CH 3 Cl (Andreae and Merlet, 2001;Sinha et al, 2003).…”

“…Ma et al (2003) extensively analyzed the particulate data measured by the NASA P3B aircraft during the TRACE-P campaign to investigate the influences of BB emissions on the fine particle ionic composition. They concluded that approximately 20% of the plumes encountered by the NASA P3B aircraft during the intensive portion of the experiment were influenced by BB emissions, based on concentrations of fine particle K + , a marker for BB emissions.…”

An investigation into seasonal and regional aerosol characteristics in East Asia using model-predicted and remotely-sensed aerosol properties

“…The high AI plume may have been caused by the BC plume emitted from biomass burning events. Spring is not only the typical dust season, but also the typical biomass burning season in East Asia (Ma et al, 2003;Song et al, 2005b, more references therein). The former usually influences the northeast Asian atmosphere, whereas the latter affects southeast Asian atmosphere, and frequently occurs in the southwestern edges of China, Thailand, Myanmar, and northern Vietnam.…”

Connections of ENSO/IOD and aerosols with Thai rainfall anomalies and associated implications for local rainfall forecasts

“…This finding is consistent with that in the work of Jayaraman (2001) showing aerosol-inhibiting rainfall over polluted areas of Thailand and is similar to that observed over the tropical Indian Ocean prior to the onset of the summer monsoon (Jayaraman, 2001). Ma et al (2003) measured biomass burning plumes originating from the Southeast Asian mainland and found aerosols with high water-soluble potassium (K + ) with some sulphate. They also estimated high black carbon emissions over the region.…”