W. T. Morgan

Chemistry and the Linkages between Air Quality and Climate Change

Climate change and air pollution are critical environmental issues both in the here and now and for the coming decades. A recent OECD report found that unless action is taken, air pollution will be the largest environmental cause of premature death worldwide by 2050. Already, air pollution levels in Asia are far above acceptable levels for human health, and even in Europe, the vast majority of the urban population was exposed to air pollution concentrations exceeding the EU daily limit values, and especially the stricter WHO air quality guidelines in the past decade. The most recent synthesis of climate change research as presented in the fifth IPCC Assessment Report (AR5) states that the warming of the climate system is unequivocal, recognizing the dominant cause as human influence, and providing evidence for a 43% higher total (from 1750 to the present) anthropogenic radiative forcing (RF) than was reported in 2005 from the previous assessment report.

Overview of the South American Biomass Burning Analysis (SAMBBA) Field Experiment

Biomass burning represents one of the largest sources of particulate matter to the atmosphere, which results in a significant perturbation to the Earth’s radiative balance coupled with serious negative impacts on public health. Globally, biomass burning aerosols are thought to exert a small warming effect of 0.03 Wm−2, however the uncertainty is 4 times greater than the central estimate. On regional scales, the impact is substantially greater, particularly in areas such as the Amazon Basin where large, intense and frequent burning occurs on an annual basis for several months (usually from August-October). Furthermore, a growing number of people live within the Amazon region, which means that they are subject to the deleterious effects on their health from exposure to substantial volumes of polluted air. Initial results from the South American Biomass Burning Analysis (SAMBBA) field experiment, which took place during September and October 2012 over Brazil, are presented here. A suite of instrumentation wa...

Biomass burning aerosol over the Amazon: analysis of aircraft,surface and satellite observations using a global aerosol model

Biomass burning is a major source of particulate matter pollution, regionally and globally. This has important implications for air quality and climate. Over South America, intense fires occur in August-September typically, providing the dominating source of atmospheric aerosols to the region. Yet considerable uncertainties in the magnitude of fire emissions remain. As such, the paper focuses on ‘improving understanding of aerosol emissions from vegetation fires’ by considering three different fire emission datasets (namely GFED4.1, GFAS1.2 and FINN1.5) to account for fire emissions in their modelling work. The authors used a global aerosol model (GLOMAP) to study how the simulated particulate matter (PM) concentration and aerosol optical thickness (AOT) are affected by the three different fire emission inventories. These results are compared against a comprehensive set of surface, aircraft and satellite observations collected over the Amazon region during September 2012. The authors have highlighted the spatial and temporal variation in the three different fire emissions and how it affects simulated quantities. Overall, the authors conclude that GLOMAP has skill in predicting reasonable surface concentration and vertical profile of PM over South America despite noticeable differences between the emission inventories. However, GLOMAP simulated AOT is found to be systematically underestimated. The authors therefore recommend caution when evaluating global models using AOTs to constrain particulate emissions from fires.

Case study analysis of biomass burning plumes observed over Brazil during SAMBBA, September 2012

Biomass burning is a huge source of atmospheric aerosols and is poorly understood leading to large uncertainties in estimates of radiative forcing of climate. Aerosols have both a direct effect on climate by reflecting and absorbing solar radiation and an indirect effect by acting as cloud condensation nuclei (CCN) and ice nuclei (IN). Biomass burning aerosols are produced from burning of vegetation with the vast majority occurring in the tropics. This research presents data collected during the aircraft campaign of the South American Biomass Burning Analysis (SAMBBA) project during September and October 2012. A smouldering rainforest fire and a flaming savannah-like fire were selected for in-depth case studies of the atmospheric plume constituents and provide a comparison between the two fire types. The physiochemical characterization of the two plumes are identified, with preliminary results showing a significant difference in the black carbon concentration of the two plumes; 6μg m−3 for the smouldering...