Visualizing Pyroclimotology

Benjamin Hatchett , T. Todd Lindley, John Abatzoglou, Ansley Baring, Alexander Gershunov, Kristen Guirguis, Robert Munroe, Nick J. Nauslar, Eli Orland, Alan M. Rhoades, Karen C. Short, Rochelle P. Worsnop

Background: Wildland fire activity often demonstrates distinct seasonality adhering to the alignment of climatologically favorable fuels, weather, and ignitions for wildfire or prescribed burning. Improved characterization of conditions that increase fire ignition probabilities, extreme fire behavior, and beneficial fire potential would enhance our understanding of fire regimes and provide insight for future wildland fire management. 

Methods: We apply a commonly-utilized tool–the climograph–to visually communicate historical wildland fire activity by demonstrating fire seasonality, interannual variability, and past individual fire events at daily resolution using satellite observations to three distinct fire-prone and fire-requiring areas. 

Results: Detection counts and cumulative fire radiative power in the resulting pyroclimographs provide first-order indicators of changes in fire activity occurring within- and out-of-season for the fire type (i.e., wildfires or prescribed burns). Using a case study of coastal Southern California, we show how pyroclimographs vary as the region of interest shifts and how their interpretation can be complemented by including climatological interpretations of additional fire environment data. Pyroclimographs also help characterize the fraction of fire radiative power–a proxy for emissions and burn severity–contributed from few or many events, i.e., the number of days contributing 50% or 90% of total fire radiative power since satellite observations began.

Conclusions: Information contained within a pyroclimograph may help track current conditions, identify factors associated with past fire occurrence, or understand typical timing of smoke impacts and their sources, all of which can be interpreted in the context of evolving real-time conditions and used for longer-term planning. Given the current ubiquity and projected increase of wildland fire in many regions, we recommend considering pyroclimographs as a visualization tool supporting varied applications where information regarding wildland fire seasonality and characteristics will benefit users.