Characterization of Texas Wildfires during the 2011-2014 Drought: A Prelude to Identifying Chemical Signatures of Smoke in Rain

Thomas Williamson1, Alexandra G. Ponette-González2, Kathleen Weathers3 and Michael Olson4

From 2011 to 2014, the most severe and intense drought in Texas recorded history led to widespread wildfires across the state, with unknown effects on atmospheric nutrient and pollutant deposition.  This research aims to: (1) characterize the frequency, magnitude, and spatiotemporal distribution of Texas wildfires and (2) examine the influence of wildfire on rainwater chemistry during this exceptional drought period. We coupled wildfire data from the Monitoring Trends in Burn Severity (MTBS) database and the Hazard Mapping Fire and Smoke (HMS) product from the National Atmospheric and Oceanic Administration to begin to address these objectives. During the focal period, 324 wildfires burning ≥405 ha were recorded, 234 of which occurred in 2011. Over the entire period, we identified 17 extreme wildfires, defined as those falling in the 95th percentile of hectares burned. These fires represented 5% of all wildfires but accounted for 90% of the total hectares burned from 2011 to 2014. Extreme wildfires were also spatially concentrated, with 14 of 17 occurring in West Texas ecoregions (i.e., Chihuahuan Desert, High Plains, Southwestern Tablelands, Edwards Plateau). The HMS data showed that the Texas NTN sites with the highest number of registered smoke days in 2011 were TX03 (Beeville; n = 81) and TX56 (LBJ National Grasslands, n = 73). These sites were also more affected by heavy smoke days compared to the other sites. The primary origins of smoke at Beeville were Texas (25), Mexico (21), and the Gulf of Mexico (21). LBJ was heavily impacted by these same source areas, but was also affected by neighboring states New Mexico, Oklahoma, and Arkansas). Future work will investigate chemical signatures of smoke in rain to determine wildfire impacts on deposition loading to ecosystems.

 

1Department of Geography and the Environment, University of North Texas, thomaswilliamson@my.unt.edu
2Department of Geography and the Environment, University of North Texas, alexandra.ponette@unt.edu
3Cary Institute of Ecosystem Studies, weathersk@caryinstitute.org
4University of Wisconsin-Madison, mrolson@wisc.edu