Temporal and spatial structure in a daily wildfire-start data set from the western United States (1986–96)
P. J. Bartlein A F , S. W. Hostetler B , S. L. Shafer C , J. O. Holman B D and A. M. Solomon EA Department of Geography, University of Oregon, Eugene, OR 97403-1251, USA.
B US Geological Survey, Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
C US Geological Survey, 3200 SW Jefferson Way, Corvallis, OR 97331, USA.
D TerraSeer, Inc., 516 N. State St., Ann Arbor, MI 48104, USA.
E US Department of Agriculture, Forest Service, Arlington, VA 22209, USA.
F Corresponding author. Email: bartlein@uoregon.edu
International Journal of Wildland Fire 17(1) 8-17 https://doi.org/10.1071/WF07022
Submitted: 11 November 2006 Accepted: 21 September 2007 Published: 14 February 2008
Abstract
The temporal and spatial structure of 332 404 daily fire-start records from the western United States for the period 1986 through 1996 is illustrated using several complimentary visualisation techniques. We supplement maps and time series plots with Hovmöller diagrams that reduce the spatial dimensionality of the daily data in order to reveal the underlying space–time structure. The mapped distributions of all lightning- and human-started fires during the 11-year interval show similar first-order patterns that reflect the broad-scale distribution of vegetation across the West and the annual cycle of climate. Lightning-started fires are concentrated in the summer half-year and occur in widespread outbreaks that last a few days and reflect coherent weather-related controls. In contrast, fires started by humans occur throughout the year and tend to be concentrated in regions surrounding large-population centres or intensive-agricultural areas. Although the primary controls of human-started fires are their location relative to burnable fuel and the level of human activity, spatially coherent, weather-related variations in their incidence can also be noted.
Additional keywords: annual cycle of fires, fire incidence, Hovmöller diagram, human-caused fires, lightning-caused fires, time–space plots, time–space variation, US National Fire Occurrence Database, wildfire outbreaks.
Acknowledgements
The present research was supported by the Joint Fire Sciences Program (BLMIA 1422RAI01–0040), NSF grants ATM-9910638 and ATM-0117160, and the US Geological Survey Water Resources Division and Earth Surface Dynamics Program. The National Fire Occurrence Database was obtained from the Fire Sciences Laboratory, Rocky Mountain Research Station, USDA Forest Service website at http://www.fs.fed.us/fire/fuelman/. We thank two anonymous reviewers and R. S. Anderson for comments.
Contributions: All authors contributed to the overall conceptual design of the analysis, and to the final manuscript. Bartlein created the figures, Bartlein, Hostetler and Shafer drafted the manuscript, and Holman contributed to the data analyses.
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