Wildfire Behavior, Winds, and Chemistry Measured from Mobile Platforms during the California Fire Dynamics Experiment (CalFiDE)

The social, economic, and ecological impacts of wildfires are increasing over much of the U.S. and globally, partially due to our changing climate and build-up of fuels from past forest management practices. This creates a need to improve coupled fire-atmosphere forecast models and to better our understanding of physical processes linking atmospheric conditions to fire behavior and vice versa. However, fulfilling these needs is difficult due to scarcity of observations for many key fire-atmosphere interactions, including updraft evolution and plume injection height, plume entrainment processes, fire intensity and rate-of-spread, and plume chemistry. Intensive observations of such fire-atmosphere coupling processes over active wildfires are rare due to the logistical challenges and scales involved. The California Fire Dynamics Experiment (CalFiDE) was designed to address these observational needs, using Doppler lidars, high-resolution multispectral imaging, and in-situ air quality instruments on a NOAA Twin Otter research aircraft, along with Doppler lidars, radar, and other instrumentation on multiple ground-based mobile platforms. Five wildfires were studied across northern California and southern Oregon over 16 flight days from 28 August to 25 September 2022, including air quality observations and a breadth of fire stages from less active smoldering fires to large blow-up days featuring pyroCb. Satellite observations contributed additional aerosol measurements and regional context of the smoke plume structures and composition. This presentation will summarize the scientific objectives, platforms and instruments deployed, coordinated sampling strategies, and present some preliminary results.

Missions were designed to optimize observations of the spatial structure and temporal evolution of each fire from early afternoon until sunset during consecutive days. The coordination of mobile platforms enabled four-dimensional sampling strategies during CalFiDE that will improve understanding of fire-atmosphere dynamics, aiding in model refinement and prediction capability. Observations included repeated flight legs directly over active areas of the fire where strong updrafts developed, revealing plume dynamics and smoke injection contextualized by infrared imaging of the fire. Additional measurements relevant for air quality included emission ratios linked to ozone production efficiency downwind of the fire, as well as estimated aerosol concentration profiles from the lidar backscatter to monitor the evolution of smoke-filled valleys. The CalFiDE dataset is the first of its kind, integrating airborne infrared imagery simultaneous with lidar, in-situ, and radar measurements on mobile platforms to sample landscape-scale wildfires.