Wildfire Simultaneity – Correlation Between US Regions
Correlation of fire simultaneity and its statistical significance between Geographic Area Coordination Centers (GACCs) in the US as measured using the Kendall correlation coefficient. Simultaneity is defined as the number of fires co-occuring in each pair of GACCs in a given month. Fires of a given size that occur in the same month in different GACCs are considered simultaneous fires in those GACCs. Each row corresponds to a fire size designation: 1000+ acres (all large fires, or ALF), 75th percentile (very large fires, or VLF) and 90th percentile (extremely large fires, or ELF). Percentiles are determined by the historic record within each GACC. The values reported in the table represent the correlation between the regions identified in the row and column labels and the color identifies the statistical significance level (i.e. spatial autocorrelation). P-values smaller than 0.05 are interpreted as significant or detectable (light green), p-values smaller than 0.01 are interpreted as strongly significant (green), and p-values smaller than 0.001 are interpreted as very strongly significant (dark green). Note that a positive correlation does not necessarily imply two GACCs experiencing many simultaneous fires, as it could also indicate two GACCs simultaneously not experiencing fire. This figure compares correlation across two decades (1984-1994 and 2009-2019), which reflects a general increase in magnitude and significance over time. Data on simultaneous wildfire occurrence come from the Monitoring Trends and Burn Severity (MTBS) project. The approach is based on Podschwit & Cullen (2020) https://doi.org/10.1071/WF19150. This visualization was made as part of NSF Growing Convergence Project 2019762.
