The following chapters include data, methods, analyses, results and conclusions that address the research objectives of this study. Chapter 2 presents an overview of the main features, settings, performance and limitations of the software used
to develop a climatology of smoke plumes across the Amazon for 2005-2012. This chapter addresses the first research objective. Chapter 3 presents an analysis of the climatology of smoke plume heights derived from satellite observations and assesses the main drivers of variability on smoke plume heights across the region, which directly addresses first and second research objectives. This chapter is included as a manuscript that was published on February 8th, 2019 in the Atmospheric Chemistry and Physics journal (ACP). Chapter 4 presents a modelling analysis of the impact of the vertical distribution of biomass burning on ozone and its precursors and assess the influence of Amazonian biomass burning on surface ozone and air quality over the Amazon region. This chapter is inserted as a manuscript to be submitted to ACP. Chapter 5 provides conclusions from all the analyses conducted in this work and recommendations for future research. Appendix A includes supplementary
information for chapter 3. Appendix B includes supplementary information for
MISR and MINX: Developing a
biomass burning smoke plume
climatology across the Amazon
2.1
Introduction
Remote sensing techniques allow observing the spatial and temporal distribution of aerosols in the atmosphere, which is crucial to study their impacts on climate
and air quality. Passive remote sensing techniques detect the natural radiation
reflected or emitted by features under cloud-free conditions. They provide high spatial and temporal coverage, but limited accuracy on the vertical aerosols distri- bution. These passive techniques include Radiometry, Imaging Radiometry, Spec- trometry and Spectroradiometry. The latter is used by the Multi-angle Imaging SpectroRadiometer (MISR) combined with multi-image matching stereoscopic tech-
niques, based on the principle of parallax (Diner et al., 1998). An important ad-
vantage of this technique is that it relies uniquely on geometry and no calibration is needed, but its major limitation is its low sensitivity to thin aerosol features without a well-defined contour that is not clearly discernible from the background. On the
other hand, active remote sensing techniques send a pulse of energy and receive the radiation reflected. These techniques include Radar, Scatterometry, Laser alti- metry and LIDAR, such as the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), on board the CALIPSO satellite. CALIOP provides high accurate aer-
osol scattering profiles (Winker et al.,2009) but extremely low spatial coverage due
to its narrow path (∼60 m).
MISR and CALIOP have been widely used in the study of the vertical distribu-
tion of aerosol plumes and clouds in the atmosphere over several regions (Val Martin
et al., 2010, Amiridis et al., 2010, Jian and Fu, 2014, Huang et al., 2015). For ins-
tance, over North America, Val Martin et al. (2010) developed an extensive 5-year
climatology of smoke plume heights based on height-retrievals derived using MISR
imagery. Similarly, Jian and Fu (2014) and Tosca et al. (2011) characterised smoke
plume heights during the burning seasons of 2001–2009/2010, over tropical regions
in Asia and Mims et al. (2010), over grassland fires in Australia. Using observa-
tions made by CALIOP, Huang et al. (2015) examined the most probable height
of dust and smoke layers over six fire impacted regions and Amiridis et al. (2010)
investigated aerosols vertical distribution and smoke top heights from agricultural burning in Europe. All these studies showed the large variability in smoke plumes across biome, season and region, as well as demonstrated that although most smoke concentrates in the boundary layer, where it is well-mixed, a variable but significant percentage of generally, low-density smoke reaches the free troposphere, as a result of favourable fire and local weather conditions, and can be transported long-range distances. MISR and CALIOP performance and sensitivity are disparate. Speci- fically MISR provides near-source constraints on the vertical distribution of smoke and allows to study smoke plume dynamics on a plume-by-plume case.
The Amazon region is a major fire region, which contributes largely to the global
fire emissions (Van der Werf et al., 2010). However, despite its important role in
the distribution and transport of global biomass burning products, no study has yet developed a climatology of smoke plume heights over the region. The present study
aims at improving the vertical distribution of biomass burning emissions represented in Earth system models (ESM) over the Amazon. For that, MISR capabilities are exploited to develop a large dataset of smoke plume heights during the burning seasons (July to November) from 2005–2012. This is the first time that such a comprehensive study of the vertical distribution of biomass burning emissions has ever been done over the Amazon. The smoke plume database developed over the
Amazon presented in Chapter 3 (Gonzalez-Alonso et al., 2019) was created with
the MINX interactive tool (Nelson et al., 2008b, 2013), using the MISR imagery
and MODIS thermal anomalies (Diner et al.,1998,Giglio et al.,2003). Because the
use of MINX requires some understanding of the software and algorithms used, this chapter describes the principal features of the MISR instrument and performance of MINX, with focus on the Amazon smoke plume climatology.