Drought In 1860
North American Drought Atlas
My original training and professional work experience were in broadcast and severe storms meteorology. In graduate school, I expanded my interests into historical climatology, dendroclimatology, climate variability, and climate change. Now as a broadly trained atmospheric scientist, I use a wide array of datasets from modern meteorology and climatology data to historical instrumental and documentary data to paleoclimate data from tree rings to investigate extreme weather and climate events at a variety of time scales. A list of funded projects I have worked on is below. This is not an exhaustive list of all my research though. See my curriculum vitae (link below) for a complete listing of publications, conference presentations, and active and past graduate student projects. My Google Scholar, ResearchGate, and LinkedIn profiles (linked icons above) also have a listing of publications and links to the articles.
Prospective graduate students having interests along these lines and are interested in the M.A., M.S., or Ph.D. programs in the Department of Earth Sciences at the University of Memphis are encouraged to e-mail me via the envelope link above.
Currently Funded Projects
Funding: Tennessee Department of Transportation (TDOT)
This is a collaborative project with Claudio Meier (Civil Engineering, University of Memphis) and the United States Geological Survey (USGS) in Nashville, TN. TDOT uses equations developed by the USGS to estimate peak flows through all structures with a drainage area greater than approximately 500 acres. However, these equations for urban areas have not been updated since 1984. The overall problem in the case of Tennessee involves multiple aspects: (i) Previous work on the topic is aged and existing equations do not consider non-stationarity in either land use or rainfall extremes, (ii) few cities have gaged urban watersheds, and all of these are located within only three of the five main physiographic zones within TN, (iii) number of stations, record lengths and the range of variability in watershed characteristics needed for traditional regression analyses are very limited, and (iv) there is a need to disentangle the effects of urbanization trends from any potential changes in extreme precipitation, and predictive equations should explicitly incorporate these drivers, so as to be useful in the future. The project’s objective is to develop, within the constraints of data availability, the best possible sets of equations for estimating peak flows in urban areas of Tennessee and then implement them in the USGS’s StreamStats software, ensuring that the program can automatically compute the different parameters and variables included in the equations.
Past Funded Projects
Funding: University of Memphis, Research Investment Fund, Team Initiation Grant
This project with Claudio Meier (Civil Engineering, University of Memphis) and Laura Saija (City and Regional Planning, University of Memphis) obtained internal seed money from the University of Memphis to initiate a permanent, interdisciplinary research team to study and develop low-tech, highly applicable, community-based strategies for operationalizing concepts of urban resilience to extreme rainfall events and, more generally, issues surrounding the hydrological cycle in the city context.
Two interdisciplinary, graduate-level classes were taught in the Fall 2017 and Spring 2018 semesters (Urban Resilience to Flooding I and II). Graduate students gave presentations to community partners at the end of the Fall 2017 semester, and in the Spring 2018 students proposed low-cost, low-tech solutions to BLDG Memphis. We are currently seeking funding to expand this project nationally and internationally.
Funding: NSF Paleoclimate Program, Paleo Perspectives on Climate Change (Arkansas = AGS-1266014, Columbia = AGS-1301587, Memphis = AGS-1266015)
This collaborative research project involved the University of Arkansas, Lamont-Doherty Earth Observatory of Columbia University, the University of Memphis, and NASA's Goddard Institute for Space Studies. This project used 439 selected tree-ring chronologies that are significantly correlated with December-April precipitation totals and 547 different chronologies correlated with May-July totals to develop the first gridded reconstructions of both cool and warm season precipitation totals across North America. The December-April and May-July seasons were used because they are most representative of the monthly precipitation signals found in the largest number of discretely correlated chronologies. The discrete subsets of tree-ring chronologies were then statistically calibrated with December-April or May-July precipitation totals at 6,812 North American grid points (at 0.5 degree grid spacing) using a localized principal components regression procedure during the period 1928-1978 in common to all tree-ring chronologies and instrumental precipitation data. The gridded reconstructions of cool and warm season precipitation were validated upon comparison with independent precipitation data from 1901-1927 and extend back for 500- to 2,000-years for most of the continent, depending on the length of the tree-ring chronologies located near each grid point.
This research has produced eight publications so far (Cook et al. 2016, WIREs Climate Change; Cook et al. 2018, Journal of Geophysical Research: Atmospheres; Howard et al. 2018, Climate Dynamics; Stahle et al. 2016, Quaternary Science Reviews; Stahle et al. 2015, Tree-Ring Research; and Torbenson et al. 2016, Tree-Ring Research, Torbenson and Stahle 2018, Journal of Climate; Torbenson et al. 2018, Paleooceanography and Paleoclimatology). Additional papers on the drought portal (see below) and a new seasonal precipitation atlas for North America are forthcoming.
A portal of webtools for all tree-ring reconstructed drought atlases, drought.memphis.edu, was launched at the American Meteorological Society Annual Meeting in January 2018.
Funding: NOAA Climate Change and Detection, Paleoclimatology (NA08OAR4310727)
Part of my postdoctoral funding with Dave Stahle at the University of Arkansas came from this project. This research project reanalyzed existing tree-ring collections from the Southeast and Southwest to build new earlywood, latewood, total ring width, and adjusted latewood width chronologies. These new chronologies were then used to derive separate millennium-long reconstructions of cool and warm season precipitation. A review of the paleoclimate applications of long tree-ring chronologies derived from living and subfossil baldcypress trees in the U.S., Mexico, and Guatemala has been published using these new chronologies (Stahle et al. 2012, Quaternary Science Reviews). A second manuscript improved on the chronological "gap" from AD 1250 to 1400 at Mesa Verde, Colorado (Stahle et al. 2015, Tree-Ring Research).
Funding: NSF Paleoclimate Program (ATM-0753399)
Part of my postdoctoral funding with Dave Stahle at the University of Arkansas came from this project. The project developed the first exactly dated millennium-long chronology of tree growth and climate history in central Mexico (Stahle et al. 2011, Geophysical Research Letters), and investigated the ocean-atmospheric dynamics responsible for drought and wetness over the region (Stahle et al. 2012, Climate Dynamics). A review of the paleoclimate applications of long tree-ring chronologies derived from living and subfossil baldcypress trees in the U.S., Mexico, and Guatemala has also been published (Stahle et al. 2012, Quaternary Science Reviews).
Funding: NSF Doctoral Dissertation Research Improvement Grant (BCS-0622894)
This was my Ph.D. project that recovered daily temperature and precipitation data from selected 19th century stations in Kansas, Missouri, and Oklahoma to extend the temperature and precipitation history of northeastern Kansas backward into the 19th century (Burnette et al. 2010, Journal of Climate; Burnette and Stahle 2013a, Climatic Change). Helpful methods and computer code were also developed to facilitate additional development of historical climate data across the United States (Burnette and Stahle 2013b, Computers and Geosciences).