CAREER: Hierarchical Models for Spatial Extremes

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Rare events can have crippling effects on economies, infrastructure, and human health and well being. But in order to make sound decisions, understanding how large the most severe events are likely to be is imperative. The PI will focus on developing statistical tools for understanding the spatial structure of the most extreme events. These new tools will improve on existing models because they will be both more realistic and more computationally tractable. The PI will also apply these tools to help scientists and policymakers study risks posed by severe environmental phenomena like inland floods, wildfires, and coastal storm surges. Furthermore, the PI will organize workshops to foster closer integration of statistical and Earth science research, as well as develop graduate courses and a textbook focused on modern statistical methods for Earth science.The PI will develop stochastic models for extreme events in space that are 1) flexible enough to transition across different classes of extremal dependence, and 2) permit inference through likelihood functions that can be computed for large datasets. It will accomplish these modeling goals by representing stochastic dependence relationships conditionally, which will induce desirable tail dependence properties and allow efficient inference through Markov chain Monte Carlo (MCMC). The first research component will develop sub-asymptotic models for spatial extremes using max-infinitely divisible (max-id) processes, a generalization of the limiting max-stable class of processes, based on a conditional representation. The second research component will develop sub-asymptotic spatial models for extremes based on scale mixtures of spatial Gaussian processes. The PI will conduct closely interwoven computational development and theoretical explication of the joint tail dependence that the proposed hierarchically specified max-id and scale mixture processes induce. Finally, the PI will apply these models to problems of high societal impact, such as extreme precipitation risk, wildfire susceptibility, and coastal storm surge exposure. The PI will enhance connections between extreme value statisticians and communities of climate and atmospheric scientists, mitigation researchers, and stakeholders, through 1) biannual international workshops on weather and climate extremes, 2) a Ph.D. level course in spatial statistics which will include new advances and applications of spatial extremes, and 3) writing the textbook Modern Statistics for Earth Scientists. The PI also will add modules on extremes to Penn State's Sustainable Climate Risk Management (SCRiM) summer school, and contribute to SCRiM's electronic resources and interactive teaching materials for educators, decision makers, underrepresented groups, and the general public. The PI will strengthen existing collaborations with government agencies which are responsible for communicating and mitigating risk to the public posed by extremal environment phenomena.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.