Abstract
Abstract. The dispersion of particles from wildfires, volcanic eruptions, dust storms, and other aerosol sources can affect many environmental factors downwind, including air quality. Aerosol injection height is one source attribute that mediates downwind dispersion, as wind speed and direction can vary dramatically with elevation. Using plume heights derived from space-based, multi-angle imaging, we examine the impact of initializing plumes in the NOAA Air Resources Laboratory's Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model with satellite-measured vs. nominal (model-calculated or VAAC-reported) injection height on the simulated dispersion of six large aerosol plumes. When there are significant differences in nominal vs. satellite-derived particle injection heights, especially if both heights are in the free troposphere or if one injection height is within the planetary boundary layer (PBL) and the other is above the PBL, differences in simulation results can arise. In the cases studied with significant nominal vs. satellite-derived injection height differences, the HYSPLIT model can represent plume evolution better, relative to independent satellite observations, if the injection height in the model is constrained by hyper-stereo satellite retrievals.
Highlights
More than 5.5 million people worldwide die prematurely every year due to household and outdoor air pollution (Forouzanfar et al, 2015)
One factor that determines the impact of the injection height on plume dispersion is whether the injection height is above the planetary boundary layer (PBL)
As wind speed and direction are generally different within vs. above the PBL, a model simulation is much more likely to approximate observations if the assumed injection height is on the correct side of this boundary
Summary
More than 5.5 million people worldwide die prematurely every year due to household and outdoor air pollution (Forouzanfar et al, 2015). The height of aerosol plumes produced by wildfires, volcanic eruptions, and dust storms has a large influence on where the particles are transported, and their environmental impacts. If aerosols are injected into the atmosphere above the planetary boundary layer (PBL) – or if they are entrained into the free troposphere after injection – they can be transported vast distances by free-tropospheric winds, causing aviation hazards, impacting regional-scale temperatures, cloud properties, and precipitation, and affecting ground-level air quality at great distances from the source (e.g., Colarco et al, 2004). The stereo technique provides plume heights with reasonable certainty in near-source regions, where features in the plume can be identified in multiple, angular views (e.g., Nelson et al, 2013). Stereo plume-height retrieval can extend to tens or even hundreds of kilometers downwind from the source
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