NASA - National Aeronautics and Space Administration

Plume heights from wildfires are used in climate modeling to predict and understand trends in aerosol transport. This paper examines whether smoke from grassland fires in the desert regions of western and central Australia ever rises above the atmospheric boundary layer. Three methods for deriving plume heights from the Multi-angle Imaging SpectroRadiometer (MISR) instrument were utilized: 1) the MISR standard stereo-height algorithm; 2) the MISR enhanced stereo product; and 3) the MISR INteractive eXplorer (MINX) v.1 tool. To provide context and to search for correlative factors, stereo heights were combined with fire radiant energy flux from the Moderate Resolution Imaging Spectroradiometer instrument, atmospheric structure information from the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis project model, surface cover from the Australia National Vegetation Information System, and forward and backward trajectories from the National Oceanic and Atmospheric Administration Hybrid Single-Particle Lagrangian Integrated Trajectory model. Although most smoke plumes concentrate in the near-surface boundary layer as expected, some appear to rise higher. Smoke that gets above the boundary layer will travel farther, remain in the atmosphere longer, and therefore have a larger environmental impact. It was previously thought unlikely for grassland fires to inject smoke above the boundary layer. Our findings suggest that climate modelers should reevaluate common assumptions about the heights of smoke plumes when producing aerosol transport models involving grassland fires. A closer examination of grassland fire energetics may also be warranted.