76 results on '"Daniel Cooley"'
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2. Center Pivot Irrigation Systems and Where to Find Them: A Deep Learning Approach to Provide Inputs to Hydrologic and Economic Models
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Daniel Cooley, Reed M. Maxwell, and Steven M. Smith
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deep learning—artificial neural network ,agricultural economic data ,groundwater use ,hydrologic modeling ,economic modeling ,Environmental technology. Sanitary engineering ,TD1-1066 - Abstract
Availability and quality of administrative data on irrigation technology varies greatly across jurisdictions. Technology choice, however, will influence the parameters of coupled human-hydrological systems. Equally, changing parameters in the coupled system may drive technology adoption. Here we develop and demonstrate a deep learning approach to locate a particularly important irrigation technology—center pivot irrigation systems—throughout the Ogallala Aquifer. The model does not rely on super computers and thus provides a model for an accessible baseline to train and deploy on other geographies. We further demonstrate that accounting for the technology can improve the insights in both economic and hydrological models.
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- 2021
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3. A Survey of Spatial Extremes
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Daniel Cooley, Jessi Cisewski, Robert J. Erhardt, Elizabeth Mannshardt, Soyoung Jeon, Bernard Oguna Omolo, and Ying Sun
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copula ,extremal coefficient ,hierarchical model ,madogram ,max-stable process ,multivariate extreme value distribution ,Statistics ,HA1-4737 ,Probabilities. Mathematical statistics ,QA273-280 - Abstract
We survey the current practice of analyzing spatial extreme data, which lies at the intersection of extreme value theory and geostatistics. Characterizations of multivariate max-stable distributions typically assume specific univariate marginal distributions, and their statistical applications generally require capturing the tail behavior of the margins and describing the tail dependence among the components. We review current methodology for spatial extremes analysis, discuss the extension of the finite-dimensional extremes framework to spatial processes, review spatial dependence metrics for extremes, survey current modeling practice for the task of modeling marginal distributions, and then examine max-stable process models and copula approaches for modeling residual spatial dependence after accounting for marginal effects.
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- 2012
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4. Autonomous Apple Fruitlet Sizing and Growth Rate Tracking using Computer Vision.
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Harry Freeman, Mohamad Qadri, Abhisesh Silwal, Paul O'Connor, Zachary B. Rubinstein, Daniel Cooley, and George Kantor
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- 2022
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5. Center Pivot Irrigation Systems as a Form of Drought Risk Mitigation in Humid Regions
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Daniel Cooley and Steven Smith
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- 2022
6. Nonlinear model predictive thermal dose control of thermal therapies: experimental validation with phantoms.
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Dhiraj Arora, Mikhail Skliar, Daniel Cooley, Adam Blankespoor, Jeff Moellmer, and Robert B. Roemer
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- 2004
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7. The pairwise beta distribution: A flexible parametric multivariate model for extremes.
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Daniel Cooley, Richard A. Davis, and Philippe Naveau
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- 2010
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8. Constrained Predictive Control of Thermal Therapies for Minimum-Time Delivery of Thermal Dose.
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Dhiraj Arora, Mikhail Skliar, Daniel Cooley, and Robert B. Roemer
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- 2007
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9. Consistency Is Key When Setting a New World Record for Running 10 Marathons in 10 Days
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Claire Harrison, Michael Graham, Georgia Campbell, Russell Best, Nicolas Berger, and Daniel Cooley
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Marathon ,Health, Toxicology and Mutagenesis ,Marathon Running ,Article ,world record ,Running ,Animal science ,Oxygen Consumption ,Weight loss ,Heart Rate ,Heart rate ,energy expenditure ,medicine ,Humans ,Energy deficit ,Treadmill ,Rating of perceived exertion ,ultra-endurance ,pacing ,business.industry ,Public Health, Environmental and Occupational Health ,VO2 max ,Energy expenditure ,Exercise intensity ,Exercise Test ,Medicine ,Female ,medicine.symptom ,business ,Energy Metabolism ,human activities - Abstract
Background: We describe the requirements and physiological changes when running 10 consecutive marathons in 10 days at the same consistent pace by a female ultra-endurance athlete. Methods: Sharon Gayter (SG) 54 yrs, 162.5 cm, 49.3 kg maximal oxygen uptake (VO2 max) 53 mL/kg−1/min−1. SG completed 42.195 km on a treadmill every day for 10 days. We measured heart rate (HR), Rating of Perceived Exertion (RPE), oxygen uptake (VO2), weight, body composition, blood parameters, nutrition, and hydration. Results: SG broke the previous record by ~2.5 h, with a cumulative completion time of 43 h 51 min 39 s. Over the 10 days, weight decreased from 51 kg to 48.4 kg, bodyfat mass from 9.1 kg to 7.2 kg (17.9% to 14.8%), and muscle mass from 23.2 kg to 22.8 kg. For all marathons combined, exercise intensity was ~60% VO2 max, VO2 1.6 ± 0.1 L.min−1/32.3 ± 1.1 mL.kg−1.min−1, RER 0.8 ± 0, HR 143 ± 4 b.min−1. Energy expenditure (EE) was 2030 ± 82 kcal/marathon, total EE for 10 days (including BMR) was 33,056 kcal, daily energy intake (EI) 2036 ± 418 kcal (20,356 kcal total), resulting an energy deficit (ED) of 12,700 kcal. Discussion: Performance and pacing were highly consistent across all 10 marathons without any substantial physiological decrements. Although overall EI did not match EE, leading to a significant ED, resulting in a 2.6 kg weight loss and decreases in bodyfat and skeletal muscle mass, this did not affect performance.
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- 2021
10. Multiple Indicators of Extreme Changes in Snow-Dominated Streamflow Regimes, Yakima River Basin Region, USA
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Glen E. Liston, Katrina E. Bennett, Christopher A. Hiemstra, Anna M. Wagner, and Daniel Cooley
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trends ,extreme events ,Geography, Planning and Development ,Drainage basin ,hydrology ,Aquatic Science ,snow ,Biochemistry ,Yakima River basin ,Streamflow ,Water cycle ,TD201-500 ,Water Science and Technology ,geography ,geography.geographical_feature_category ,Water supply for domestic and industrial purposes ,Hydraulic engineering ,Snowpack ,Snow ,Water resources ,climate change ,SNOTEL ,Snowmelt ,Climatology ,snow water equivalent ,Environmental science ,TC1-978 - Abstract
Snow plays a major role in the hydrological cycle. Variations in snow duration and timing can have a negative impact on water resources. Excluding predicted changes in snowmelt rates and amounts could result in deleterious infrastructure, military mission, and asset impacts at military bases across the US. A change in snowpack can also lead to water shortages, which in turn can affect the availability of irrigation water. We performed trend analyses of air temperature, snow water equivalent (SWE) at 22 SNOTEL stations, and streamflow extremes for selected rivers in the snow-dependent and heavily irrigated Yakima River Basin (YRB) located in the Pacific Northwest US. There was a clear trend of increasing air temperature in this study area over a 30 year period (water years 1991–2020). All stations indicated an increase in average air temperatures for December (0.97 °C/decade) and January (1.12 °C/decade). There was also an upward trend at most stations in February (0.28 °C/decade). In December–February, the average air temperatures were 0.82 °C/decade. From these trends, we estimate that, by 2060, the average air temperatures for December–February at most (82%) stations will be above freezing. Furthermore, analysis of SWE from selected SNOTEL stations indicated a decreasing trend in historical SWE, and a shift to an earlier peak SWE was also assumed to be occurring due of the shorter snow duration. Decreasing trends in snow duration, rain-on-snow, and snowmelt runoff also resulted from snow modeling simulations of the YRB and the nearby area. We also observed a shift in the timing of snowmelt-driven peak streamflow, as well as a statistically significant increase in winter maximum streamflow and decrease in summer maximum and minimum streamflow trends by 2099. From the streamflow trends and complementary GEV analysis, we show that the YRB basin is a system in transition with earlier peak flows, lower snow-driven maximum streamflow, and higher rainfall-driven summer streamflow. This study highlights the importance of looking at changes in snow across multiple indicators to develop future infrastructure and planning tools to better adapt and mitigate changes in extreme events.
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- 2021
11. Changes in climate and its effect on timing of snowmelt and intensity-duration-frequency curves
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Daniel Cooley, Katrina E. Bennett, Christopher A. Hiemstra, A. Gelvin, Anna M. Wagner, and Glen E. Liston
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Snowmelt ,Flood forecasting ,Environmental science ,Duration (project management) ,Atmospheric sciences ,Snow ,Surface runoff ,Intensity (physics) - Abstract
Snow is a critical water resource for much of the U.S. and failure to account for changes in climate could deleteriously impact military assets. In this study, we produced historical and future snow trends through modeling at three military sites (in Washington, Colorado, and North Dakota) and the Western U.S. For selected rivers, we performed seasonal trend analysis of discharge extremes. We calculated flood frequency curves and estimated the probability of occurrence of future annual maximum daily rainfall depths. Additionally, we generated intensity-duration-frequency curves (IDF) to find rainfall intensities at several return levels. Generally, our results showed a decreasing trend in historical and future snow duration, rain-on-snow events, and snowmelt runoff. This decreasing trend in snowpack could reduce water resources. A statistically significant increase in maximum streamflow for most rivers at the Washington and North Dakota sites occurred for several months of the year. In Colorado, only a few months indicated such an increase. Future IDF curves for Colorado and North Dakota indicated a slight increase in rainfall intensity whereas the Washington site had about a twofold increase. This increase in rainfall intensity could result in major flood events, demonstrating the importance of accounting for climate changes in infrastructure planning.
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- 2021
12. 20 Years of Statistics at the National Center for Atmospheric Research
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Amanda S. Hering and Daniel Cooley
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0106 biological sciences ,010104 statistics & probability ,Statistics ,Environmental science ,Center (algebra and category theory) ,General Medicine ,0101 mathematics ,010603 evolutionary biology ,01 natural sciences ,Atmospheric research ,Statistician - Abstract
Almost every U.S.-based statistician working on problems motivated by atmospheric science is connected to the statistics program at the National Center for Atmospheric Research (NCAR). Through its ...
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- 2019
13. An evaluation of the consistency of extremes in gridded precipitation data sets
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Michael Wehner, Travis A. O'Brien, Harinarayan Krishnan, Ben Timmermans, and Daniel Cooley
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Atmospheric Science ,Multivariate statistics ,010504 meteorology & atmospheric sciences ,Extremes ,Scale (descriptive set theory) ,Precipitation ,Comparison ,Oceanography ,010502 geochemistry & geophysics ,01 natural sciences ,Physical Geography and Environmental Geoscience ,Atmospheric Sciences ,Tail dependence ,Range (statistics) ,Meteorology & Atmospheric Sciences ,Extreme value theory ,0105 earth and related environmental sciences ,Ground truth ,Rain gauge ,Brain Disorders ,Climatology ,Environmental science ,Gridded products - Abstract
© 2019, Regents of the University of California. Noting a strong imperative to understand precipitation extremes, and that considerable uncertainty affects observational data sets, this paper compares the representation of extremes in a number of widely used daily gridded products, derived from rain gauge data, satellite retrieval and reanalysis for the conterminous United States. Analysis is based upon the concept of “tail dependence” arising in multivariate extreme value theory, and we infer the level of temporal dependence in the joint tail of the precipitation probability distribution for pairwise comparisons of products. In this way, we consider the range of products more like an ensemble and examine the relationships between members, and do not attempt to define, or compare products to, some ground truth. Linear correlation between products is also computed. Considerable discrepancy between groups of products, both annually and seasonally, is linked to source data and complex terrain. In particular, products based on rain gauge data showed remarkable similarity, but differed considerably, showing almost total loss of extremal dependence during DJF in mountainous regions, when compared with satellite products. Additionally, simulated re-forecasts revealed reasonable temporal agreement with large scale generated extremes. The diversity and extent of discrepancies identified across all products raises important questions about their use, and we urge caution, particularly for products derived from satellite data.
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- 2019
14. Editorial to the special issue: Statistical modeling of environmental extremes
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Philippe Naveau, Daniel Cooley, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
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Statistics and Probability ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,010104 statistics & probability ,Management science ,010102 general mathematics ,Economics, Econometrics and Finance (miscellaneous) ,Statistical model ,0101 mathematics ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,01 natural sciences ,Engineering (miscellaneous) ,ComputingMilieux_MISCELLANEOUS ,Mathematics - Abstract
International audience
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- 2021
15. Closing the gap: Explaining persistent underestimation by US oil and natural gas production-segment methane inventories
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Jeffrey Rutherford, Evan Sherwin, Arvind Ravikumar, Garvin Heath, Jacob Englander, Daniel Cooley, David Lyon, Mark Omara, Quinn Langfitt, and Adam Brandt
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- 2020
16. Principal Component Analysis for Extremes and Application to U.S. Precipitation
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Yujing Jiang, Michael Wehner, and Daniel Cooley
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Basis (linear algebra) ,Covariance matrix ,Covariance ,Oceanography ,01 natural sciences ,Atmospheric Sciences ,010104 statistics & probability ,Matrix (mathematics) ,Geomatic Engineering ,Climatology ,Principal component analysis ,Applied mathematics ,Meteorology & Atmospheric Sciences ,0101 mathematics ,Extreme value theory ,Eigenvalues and eigenvectors ,Eigendecomposition of a matrix ,0105 earth and related environmental sciences ,Mathematics - Abstract
Author(s): Jiang, Y; Cooley, D; Wehner, MF | Abstract: We propose a method for analyzing extremal behavior through the lens of a most efficient basis of vectors. The method is analogous to principal component analysis, but is based on methods from extreme value analysis. Specifically, rather than decomposing a covariance or correlation matrix, we obtain our basis vectors by performing an eigendecomposition of a matrix that describes pairwise extremal dependence.We apply the method to precipitation observations over the contiguous United States. We find that the time series of large coefficients associated with the leading eigenvector shows very strong evidence of a positive trend, and there is evidence that large coefficients of other eigenvectors have relationships with El Nino-Southern Oscillation.
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- 2020
17. Does a concussion in adolescents increase likelihood of developing insomnia?
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Mariam Mansour, Adam Guck, Victoria Godwin, and Daniel Cooley
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medicine.medical_specialty ,business.industry ,Concussion ,Insomnia ,medicine ,Fundamentals and skills ,medicine.symptom ,business ,Psychiatry ,medicine.disease - Published
- 2021
18. A space-time skew-tmodel for threshold exceedances
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Emeric Thibaud, Brian J. Reich, Daniel Cooley, and Samuel A. Morris
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Statistics and Probability ,Mathematical optimization ,010504 meteorology & atmospheric sciences ,General Immunology and Microbiology ,Computer science ,Applied Mathematics ,Space time ,Gaussian ,Skew ,Markov chain Monte Carlo ,T-model ,General Medicine ,Bayesian inference ,01 natural sciences ,Thresholding ,General Biochemistry, Genetics and Molecular Biology ,010104 statistics & probability ,symbols.namesake ,symbols ,0101 mathematics ,General Agricultural and Biological Sciences ,Extreme value theory ,0105 earth and related environmental sciences - Abstract
To assess the compliance of air quality regulations, the Environmental Protection Agency (EPA) must know if a site exceeds a pre-specified level. In the case of ozone, the level for compliance is fixed at 75 parts per billion, which is high, but not extreme at all locations. We present a new space-time model for threshold exceedances based on the skew-t process. Our method incorporates a random partition to permit long-distance asymptotic independence while allowing for sites that are near one another to be asymptotically dependent, and we incorporate thresholding to allow the tails of the data to speak for themselves. We also introduce a transformed AR(1) time-series to allow for temporal dependence. Finally, our model allows for high-dimensional Bayesian inference that is comparable in computation time to traditional geostatistical methods for large data sets. We apply our method to an ozone analysis for July 2005, and find that our model improves over both Gaussian and max-stable methods in terms of predicting exceedances of a high level.
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- 2017
19. Modeling the upper tail of the distribution of facial recognition non-match scores
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Brett D. Hunter, Geof H. Givens, J. Ross Beveridge, and Daniel Cooley
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Statistics and Probability ,Distribution (number theory) ,Generalized Pareto distribution ,Applied Mathematics ,Statistics ,Facial recognition system ,Quantile regression ,Mathematics - Published
- 2017
20. Climate Science Needs Professional Statisticians
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Michael Wehner and Daniel Cooley
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Political science ,General Earth and Planetary Sciences ,Engineering ethics ,Climate science - Abstract
Climate science needs its own specialized “climostatisticians” as integral members of multidisciplinary research teams.
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- 2019
21. Univariate and Multivariate Extremes for the Environmental Sciences
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Daniel Cooley, Brett D. Hunter, and Richard L. Smith
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- 2019
22. Data assimilation
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Brett D. Hunter, Daniel Cooley, and Richard Smith
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Multivariate statistics ,Statistics ,Univariate ,Environmental science - Published
- 2019
23. New Exploratory Tools for Extremal Dependence: Chi Networks and Annual Extremal Networks
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Whitney K. Huang, Daniel Cooley, Imme Ebert-Uphoff, Chen Chen, and Snigdhansu Chatterjee
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0106 biological sciences ,Statistics and Probability ,Discrete mathematics ,FOS: Computer and information sciences ,Spatial structure ,Applied Mathematics ,Structure (category theory) ,Block (permutation group theory) ,Tail dependence ,Estimator ,Scale (descriptive set theory) ,Extremal dependence ,010603 evolutionary biology ,01 natural sciences ,Agricultural and Biological Sciences (miscellaneous) ,Methodology (stat.ME) ,010104 statistics & probability ,0101 mathematics ,Statistics, Probability and Uncertainty ,General Agricultural and Biological Sciences ,Extreme value theory ,Statistics - Methodology ,General Environmental Science ,Mathematics - Abstract
Understanding dependence structure among extreme values plays an important role in risk assessment in environmental studies. In this work we propose the $\chi$ network and the annual extremal network for exploring the extremal dependence structure of environmental processes. A $\chi$ network is constructed by connecting pairs whose estimated upper tail dependence coefficient, $\hat \chi$, exceeds a prescribed threshold. We develop an initial $\chi$ network estimator and we use a spatial block bootstrap to assess both the bias and variance of our estimator. We then develop a method to correct the bias of the initial estimator by incorporating the spatial structure in $\chi$. In addition to the $\chi$ network, which assesses spatial extremal dependence over an extended period of time, we further introduce an annual extremal network to explore the year-to-year temporal variation of extremal connections. We illustrate the $\chi$ and the annual extremal networks by analyzing the hurricane season maximum precipitation at the US Gulf Coast and surrounding area. Analysis suggests there exists long distance extremal dependence for precipitation extremes in the study region and the strength of the extremal dependence may depend on some regional scale meteorological conditions, for example, sea surface temperature., Comment: 26 pages, 7 figures, 1 table
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- 2019
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24. Distributionally Robust Inference for Extreme Value-at-Risk
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Robert Yuen, Stilian Stoev, and Daniel Cooley
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Statistics and Probability ,Economics and Econometrics ,021103 operations research ,Optimization problem ,Linear programming ,Euclidean space ,0211 other engineering and technologies ,Mathematics - Statistics Theory ,02 engineering and technology ,Statistics Theory (math.ST) ,01 natural sciences ,Infimum and supremum ,010104 statistics & probability ,FOS: Mathematics ,49K30, 62G32, 62G35 ,Applied mathematics ,Uncountable set ,0101 mathematics ,Statistics, Probability and Uncertainty ,Special case ,Extreme value theory ,Finite set ,Mathematics - Abstract
Under general multivariate regular variation conditions, the extreme Value-at-Risk of a portfolio can be expressed as an integral of a known kernel with respect to a generally unknown spectral measure supported on the unit simplex. The estimation of the spectral measure is challenging in practice and virtually impossible in high dimensions. This motivates the problem studied in this work, which is to find universal lower and upper bounds of the extreme Value-at-Risk under practically estimable constraints. That is, we study the infimum and supremum of the extreme Value-at-Risk functional, over the infinite dimensional space of all possible spectral measures that meet a finite set of constraints. We focus on extremal coefficient constraints, which are popular and easy to interpret in practice. Our contributions are twofold. First, we show that optimization problems over an infinite dimensional space of spectral measures are in fact dual problems to linear semi-infinite programs (LSIPs) – linear optimization problems in Euclidean space with an uncountable set of linear constraints. This allows us to prove that the optimal solutions are in fact attained by discrete spectral measures supported on finitely many atoms. Second, in the case of balanced portfolia, we establish further structural results for the lower bounds as well as closed form solutions for both the lower- and upper-bounds of extreme Value-at-Risk in the special case of a single extremal coefficient constraint. The solutions unveil important connections to the Tawn–Molchanov max-stable models. The results are illustrated with two applications: a real data example and closed-form formulae in a market plus sectors framework.
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- 2019
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25. Thermal dose control of ultrasound therapies using MR thermometry images: an in-vitro phantom study.
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Dhiraj Arora, Daniel Cooley, Trent Perry, Junyu Guo, Dennis Parker, Mikhail Skliar, and Robert B. Roemer
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- 2005
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26. Methane Leaks from Natural Gas Systems Follow Extreme Distributions
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Garvin Heath, Daniel Cooley, and Adam R. Brandt
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Leak ,Petroleum engineering ,business.industry ,Chemistry ,020209 energy ,02 engineering and technology ,General Chemistry ,Models, Theoretical ,Natural Gas ,Atmospheric sciences ,Methane ,Renewable energy ,chemistry.chemical_compound ,Variable (computer science) ,Volume (thermodynamics) ,Sample size determination ,Natural gas ,0202 electrical engineering, electronic engineering, information engineering ,Environmental Chemistry ,business ,Extreme value theory - Abstract
Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ∼15 000 measurements from 18 prior studies, we show that all available natural gas leakage data sets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the total leakage volume. While prior studies used log-normal model distributions, we show that log-normal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation o...
- Published
- 2016
27. Modeling the spatial behavior of the meteorological drivers' effects on extreme ozone
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Colette L. Heald, Daniel Cooley, Brook T. Russell, and William C. Porter
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Statistics and Probability ,010104 statistics & probability ,chemistry.chemical_compound ,Ozone ,010504 meteorology & atmospheric sciences ,chemistry ,Spatial behavior ,Ecological Modeling ,Environmental science ,0101 mathematics ,Atmospheric sciences ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2016
28. A comparison of U.S. precipitation extremes under RCP8.5 and RCP4.5 with an application of pattern scaling
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Daniel Cooley, Miranda J. Fix, Claudia Tebaldi, and Stephan R. Sain
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Atmospheric Science ,Global and Planetary Change ,010504 meteorology & atmospheric sciences ,Climate change ,Grid cell ,01 natural sciences ,010104 statistics & probability ,Community earth system model ,Climatology ,Generalized extreme value distribution ,Initial value problem ,Environmental science ,Precipitation ,0101 mathematics ,Maxima ,Scaling ,0105 earth and related environmental sciences - Abstract
Precipitation extremes are expected to increase in a warming climate, which may have serious societal impacts. This study uses two initial condition ensembles conducted with the Community Earth System Model (CESM) to investigate potential changes in extreme precipitation under two climate change scenarios over the contiguous United States. We fit non-stationary generalized extreme value (GEV) models to annual maximum daily precipitation simulated from a 30-member ensemble under the RCP8.5 scenario and a 15-member ensemble under the RCP4.5 scenario. We then compare impacts using the 1 % annual exceedance probability (AEP) level, which is the amount of daily rainfall with only a 1 % chance of being exceeded in a given year. Under RCP8.5 between 2005 and 2080, the 1 % AEP level is projected to increase by 17 % on average across the U.S., and up to 36 % for some grid cells. Compared to RCP8.5 in the year 2080, RCP4.5 is projected to reduce the 1 % AEP level by 7 % on average, with reductions as large as 18 % for some grid cells. We also investigate a pattern scaling approach in which we produce predictive GEV distributions of annual precipitation maxima under RCP4.5 given only global mean temperatures for this scenario. We compare results from this less computationally intensive method to those obtained from our GEV model fitted directly to the CESM RCP4.5 output and find that pattern scaling produces reasonable projections.
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- 2016
29. A spatial model to examine rainfall extremes in Colorado’s Front Range
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Mari R. Tye and Daniel Cooley
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Return period ,Meteorology ,Generalized extreme value distribution ,Elevation ,Rare events ,Environmental science ,Statistical model ,Point estimation ,Spatial dependence ,Extreme value theory ,Water Science and Technology - Abstract
Summary Between 9th and 16th September 2013, northeast Colorado received some of its most extreme rainfall on record. The event affected 6 major rivers and their tributaries and 14 counties, breaking observed records for accumulations from sub-daily through to annual total. NOAA’s rainfall atlases indicated that this event had an anticipated return period of 1000 years. We use the rainfall that led to the 2013 Colorado floods as a case study in order to explore how a large event can affect the generalized extreme value (GEV) parameter estimates often used by designers and planners. We employ daily rainfall observations, with at least 30 years of data, from stations across Colorado’s Front Range of the Rocky Mountains to develop a spatial statistical model for annual maximum daily rainfall. We produce estimates of relatively rare events such as the 1% Annual Exceedance Probability (AEP) level and of extremely rare events such as the return period associated with Boulder’s 2013 observation. To explore sensitivity, we compare estimates including and excluding data from 2013, and both using only individual station data and our model which borrows strength across multiple stations. We compute the uncertainty associated with all of our estimates, and find large uncertainties associated with extremely rare events. Our statistical model is a spatial hierarchical model and we employ a two-stage approach for inference which can be implemented by practitioners. Additionally, the spatial model allows us to interpolate spatially and estimate the GEV parameters at unobserved locations. A further development of the model makes use of an alternatively defined space in terms of elevation and a climate variable, rather than geographical space defined by longitude and latitude, which seems to better account for orographic effects. In addition to producing AEP level and return period estimates to the annual maximum data, we investigate sensitivity to the choice of block length. We find point estimates indicate the tail to be much heavier when a longer block length is used, but the uncertainty associated with this parameter is such that one cannot say the difference is significant. To describe the spatial extent of severe storms, we also investigate the amount of data dependence between station locations. We find evidence in the record for storms with large spatial extent, although an extremal dependence parameter estimate indicates that this dependence is relatively weak.
- Published
- 2015
30. Physiological Responses and Nutritional Intake during a 7-Day Treadmill Running World Record
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Daniel Cooley, Michael Graham, Claire Harrison, Nicolas Berger, and Russell Best
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030309 nutrition & dietetics ,Health, Toxicology and Mutagenesis ,lcsh:Medicine ,Case Report ,exercise performance ,Carbohydrate metabolism ,03 medical and health sciences ,0302 clinical medicine ,Treadmill running ,Animal science ,Heart rate ,case-study ,running ,Blood lactate ,Medicine ,Treadmill ,Rating of perceived exertion ,0303 health sciences ,ultra-endurance ,world-record ,business.industry ,lcsh:R ,Public Health, Environmental and Occupational Health ,030229 sport sciences ,Oxygen uptake ,Physiological responses ,nutrition ,business - Abstract
Ultra-running comprises running events longer than a marathon (>42.2 km). The prolonged duration of ultra-running leads to decrements in most or all physiological parameters and considerable energy expenditure (EE) and energy deficits. SG, 47 years, 162.5 cm, 49 kg, VO2max 4 mL/kg/min−1/2.37 L/min−1, ran continuously for 7 days on a treadmill in 3 h blocks followed by 30 min breaks and slept from 1–5 a.m. Heart rate (HR) oxygen uptake (VO2), rating of perceived exertion, weight, blood lactate (mmol·L−1), haemoglobin (g·dL), haematocrit (%) and glucose (mmol·L−1), and nutrition and hydration were recorded. SG ran for 17.5 h/day, covering ~120 km/day at ~7 km/h. Energy expenditure for each 24 h period was 6878 kcal/day and energy intake (EI) was 2701 kcal/day. EE was 382 kcal/h, with 66.6% from fat and 33.4% from carbohydrate oxidation. 7 day EI was 26,989 kcal and EE was 48,147 kcal, with a total energy deficit (ED) of 21,158 kcal. Average VO2 was 1.2 L·min−1/24.7 mL·kg·min−1, Respriatory echange ratio (RER) 0.80 ± 0.03, HR 120–125 b·min−1. Weight increased from 48.6 to 49.5 kg. Haemoglobin decreased from 13.7 to 11 g·dL and haematocrit decreased from 40% to 33%. SG ran 833.05 km. SG exhibits an enhanced fat metabolism through which she had a large daily ED. Her success can be attributed to a combination of physiological and psychological factors.
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- 2020
31. Setting A New World Record: The Demands Of Running 833km On Treadmill In 7 Days
- Author
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Michael Graham, Daniel Cooley, Claire Harrison, Nicolas Berger, Matthew Wright, and Russell Best
- Subjects
medicine.medical_specialty ,Physical medicine and rehabilitation ,business.industry ,Medicine ,Physical Therapy, Sports Therapy and Rehabilitation ,Orthopedics and Sports Medicine ,Treadmill ,business - Published
- 2020
32. Observed and predicted sensitivities of extreme surface ozone to meteorological drivers in three US cities
- Author
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Eric Gilleland, Alma Hodzic, Gabriele Pfister, William C. Porter, Daniel Cooley, Miranda J. Fix, and Brook T. Russell
- Subjects
Atmospheric Science ,Environmental Engineering ,010504 meteorology & atmospheric sciences ,Extreme value theory ,Statistics ,Tail dependence ,Meteorological variables ,Predictor variables ,010501 environmental sciences ,Atmospheric sciences ,01 natural sciences ,Quantile regression ,Atmospheric Sciences ,Variable (computer science) ,Surface ozone ,Atmospheric chemistry ,Environmental science ,Meteorology & Atmospheric Sciences ,0105 earth and related environmental sciences ,General Environmental Science ,Quantile - Abstract
We conduct a case study of observed and simulated maximum daily 8-h average (MDA8) ozone (O3) in three US cities for summers during 1996–2005. The purpose of this study is to evaluate the ability of a high resolution atmospheric chemistry model to reproduce observed relationships between meteorology and high or extreme O3. We employ regional coupled chemistry-transport model simulations to make three types of comparisons between simulated and observational data, comparing (1) tails of the O3 response variable, (2) distributions of meteorological predictor variables, and (3) sensitivities of high and extreme O3 to meteorological predictors. This last comparison is made using two methods: quantile regression, for the 0.95 quantile of O3, and tail dependence optimization, which is used to investigate even higher O3 extremes. Across all three locations, we find substantial differences between simulations and observational data in both meteorology and meteorological sensitivities of high and extreme O3.
- Published
- 2018
33. Improved return level estimation via a weighted likelihood, latent spatial extremes model
- Author
-
Joshua Hewitt, Daniel Cooley, Miranda J. Fix, and Jennifer A. Hoeting
- Subjects
0106 biological sciences ,Statistics and Probability ,Estimation ,FOS: Computer and information sciences ,Computer science ,Applied Mathematics ,Inference ,Statistics - Applications ,010603 evolutionary biology ,01 natural sciences ,Agricultural and Biological Sciences (miscellaneous) ,Flooding (computer networking) ,010104 statistics & probability ,Weighted likelihood ,Conditional independence ,13. Climate action ,Rare events ,Econometrics ,Applications (stat.AP) ,0101 mathematics ,Statistics, Probability and Uncertainty ,Spatial dependence ,General Agricultural and Biological Sciences ,General Environmental Science ,Quantile - Abstract
Uncertainty in return level estimates for rare events, like the intensity of large rainfall events, makes it difficult to develop strategies to mitigate related hazards, like flooding. Latent spatial extremes models reduce uncertainty by exploiting spatial dependence in statistical characteristics of extreme events to borrow strength across locations. However, these estimates can have poor properties due to model misspecification: many latent spatial extremes models do not account for extremal dependence, which is spatial dependence in the extreme events themselves. We improve estimates from latent spatial extremes models that make conditional independence assumptions by proposing a weighted likelihood that uses the extremal coefficient to incorporate information about extremal dependence during estimation. This approach differs from, and is simpler than, directly modeling the spatial extremal dependence; for example, by fitting a max-stable process, which is challenging to fit to real, large datasets. We adopt a hierarchical Bayesian framework for inference, use simulation to show the weighted model provides improved estimates of high quantiles, and apply our model to improve return level estimates for Colorado rainfall events with 1% annual exceedance probability., Comment: 31 pages, 3 figures, 3 tables
- Published
- 2018
- Full Text
- View/download PDF
34. A Nonparametric Method for Producing Isolines of Bivariate Exceedance Probabilities
- Author
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Michael Wehner, Federico Castillo, Emeric Thibaud, and Daniel Cooley
- Subjects
FOS: Computer and information sciences ,Statistics and Probability ,Multivariate statistics ,Extreme values ,Economics ,Regular variation ,Statistics & Probability ,Economics, Econometrics and Finance (miscellaneous) ,Bivariate analysis ,01 natural sciences ,Plot (graphics) ,Mathematical Sciences ,Methodology (stat.ME) ,tail ,010104 statistics & probability ,multivariate ,Engineering ,Bivariate data ,Clinical Research ,Asymptotic independence ,0502 economics and business ,Statistics ,Range (statistics) ,regular variation ,050207 economics ,0101 mathematics ,Extreme value theory ,Engineering (miscellaneous) ,Statistics - Methodology ,Mathematics ,Hidden regular variation ,05 social sciences ,Nonparametric statistics ,dependence ,extreme values ,hidden regular variation ,asymptotic independence ,Multivariate ,Smoothing - Abstract
© 2019, Springer Science+Business Media, LLC, part of Springer Nature. We present a method for drawing isolines indicating regions of equal joint exceedance probability for bivariate data. The method relies on bivariate regular variation, a dependence framework widely used for extremes. The method we utilize for characterizing dependence in the tail is largely nonparametric. The extremes framework enables drawing isolines corresponding to very low exceedance probabilities and may even lie beyond the range of the data; such cases would be problematic for standard nonparametric methods. Furthermore, we extend this method to the case of asymptotic independence and propose a procedure which smooths the transition from hidden regular variation in the interior to the first-order behavior on the axes. We propose a diagnostic plot for assessing the isoline estimate and choice of smoothing, and a bootstrap procedure to visually assess uncertainty.
- Published
- 2017
35. Rapid, Vehicle-Based Identification of Location and Magnitude of Urban Natural Gas Pipeline Leaks
- Author
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Jessica Salo, Claire J. Griebenow, Samuel D. Chamberlain, David M. Theobald, Joseph C. von Fischer, Daniel Cooley, Steven P. Hamburg, Adam Gaylord, Jay M. Ham, and Russ S. Schumacher
- Subjects
Leak ,Engineering ,Air Pollutants ,Petroleum engineering ,business.industry ,020209 energy ,Environmental engineering ,Magnitude (mathematics) ,02 engineering and technology ,General Chemistry ,Natural Gas ,Pipeline (software) ,Methane ,Pipeline transport ,chemistry.chemical_compound ,chemistry ,Natural gas ,Greenhouse gas ,Environmental monitoring ,0202 electrical engineering, electronic engineering, information engineering ,Environmental Chemistry ,Cities ,business ,Environmental Monitoring - Abstract
Information about the location and magnitudes of natural gas (NG) leaks from urban distribution pipelines is important for minimizing greenhouse gas emissions and optimizing investment in pipeline management. To enable rapid collection of such data, we developed a relatively simple method using high-precision methane analyzers in Google Street View cars. Our data indicate that this automated leak survey system can document patterns in leak location and magnitude within and among cities, even without wind data. We found that urban areas with prevalent corrosion-prone distribution lines (Boston, MA, Staten Island, NY, and Syracuse, NY), leaked approximately 25-fold more methane than cities with more modern pipeline materials (Burlington, VT, and Indianapolis, IN). Although this mobile monitoring method produces conservative estimates of leak rates and leak counts, it can still help prioritize both leak repairs and replacement of leak-prone sections of distribution lines, thus minimizing methane emissions over short and long terms.
- Published
- 2017
36. A sum characterization of hidden regular variation with likelihood inference via expectation-maximization
- Author
-
Grant B. Weller and Daniel Cooley
- Subjects
Statistics and Probability ,Multivariate statistics ,Applied Mathematics ,General Mathematics ,Monte Carlo method ,Tail dependence ,Agricultural and Biological Sciences (miscellaneous) ,Measure (mathematics) ,Combinatorics ,Expectation–maximization algorithm ,Applied mathematics ,Statistics, Probability and Uncertainty ,General Agricultural and Biological Sciences ,Extreme value theory ,Equivalence (measure theory) ,Independence (probability theory) ,Mathematics - Abstract
A fundamental deficiency of classical multivariate extreme value theory is the inability to distinguish between asymptotic independence and exact independence. In this work, we examine multivariate threshold modelling in the framework of regular variation on cones. Tail dependence is described by a limiting measure, which in some cases is degenerate on joint tail regions despite strong subasymptotic dependence in such regions. Hidden regular variation, a higher-order tail decay on these regions, offers a refinement of the classical theory. We develop a representation of random vectors possessing hidden regular variation as the sum of independent regular varying components. The representation is shown to be asymptotically valid via a multivariate tail equivalence result. We develop a likelihood-based estimation procedure from this representation via a Monte Carlo expectation-maximization algorithm which has been modified for tail estimation. The method is demonstrated on simulated data and applied to air pollution measurements.
- Published
- 2014
37. Decompositions of Dependence for High-Dimensional Extremes
- Author
-
Daniel Cooley and Emeric Thibaud
- Subjects
FOS: Computer and information sciences ,Statistics and Probability ,dimension reduction ,tail dependence ,General Mathematics ,independence ,010103 numerical & computational mathematics ,Positive-definite matrix ,01 natural sciences ,Methodology (stat.ME) ,010104 statistics & probability ,Matrix (mathematics) ,multivariate ,angular measure ,regular variation ,Statistical physics ,0101 mathematics ,Eigendecomposition of a matrix ,Independence (probability theory) ,Statistics - Methodology ,Mathematics ,inference ,Basis (linear algebra) ,Applied Mathematics ,Tail dependence ,Agricultural and Biological Sciences (miscellaneous) ,Orthant ,Transformation (function) ,Statistics, Probability and Uncertainty ,General Agricultural and Biological Sciences - Abstract
Employing the framework of regular variation, we propose two decompositions which help to summarize and describel high-dimensional tail dependence. Via transformation, we define a vector space on the positive orthant, yielding the notion of basis. With a suitably-chosen transformation, we show that transformed-linear operations applied to regularly varying random vectors preserve regular variation. Rather than model regular-variation's angular measure, we summarize tail dependence via a matrix of pairwise tail dependence metrics. This matrix is positive semidefinite, and eigendecomposition allows one to interpret tail dependence via the resulting eigenbasis. Additionally this matrix is completely positive, and a resulting decomposition allows one to easily construct regularly varying random vectors which share the same pairwise tail dependencies. We illustrate our methods with Swiss rainfall data and financial return data.
- Published
- 2016
38. A Hierarchical Model for Serially-Dependent Extremes: A Study of Heat Waves in the Western US
- Author
-
Brian J. Reich, Benjamin A. Shaby, and Daniel Cooley
- Subjects
Statistics and Probability ,Applied Mathematics ,Magnitude (mathematics) ,Climate change ,Heat wave ,Bayesian inference ,Markov model ,Agricultural and Biological Sciences (miscellaneous) ,Hierarchical database model ,Distribution (mathematics) ,Generalized Pareto distribution ,Econometrics ,Statistics, Probability and Uncertainty ,General Agricultural and Biological Sciences ,General Environmental Science ,Mathematics - Abstract
Heat waves take a major toll on human populations, with negative impacts on the economy, agriculture, and human health. As a result, there is great interest in studying the changes over time in the probability and magnitude of heat waves. In this paper we propose a hierarchical Bayesian model for serially-dependent extreme temperatures. We assume the marginal temperature distribution follows the generalized Pareto distribution (GPD) above a location-specific threshold, and capture dependence between subsequent days using a transformed max-stable process. Our model allows both the parameters in the marginal GPD and the temporal dependence function to change over time. This allows Bayesian inference on the change in likelihood of a heat wave. We apply this methodology to daily high temperatures in nine cities in the western US for 1979–2010. Our analysis reveals increases in the probability of a heat wave in several US cities. This article has supplementary material online.
- Published
- 2013
39. A constrained least-squares approach to combine bottom-up and top-down CO2 flux estimates
- Author
-
Daniel Cooley, Andrew Schuh, Stephen M. Ogle, Thomas Lauvaux, and F. Jay Breidt
- Subjects
Statistics and Probability ,Constraint (information theory) ,Inventory valuation ,Covariance matrix ,Computation ,Statistics ,Inverse ,Flux ,Statistical model ,Variance (accounting) ,Statistics, Probability and Uncertainty ,General Environmental Science ,Mathematics - Abstract
Terrestrial CO2 flux estimates are obtained from two fundamentally different methods generally termed bottom-up and top-down approaches. Inventory methods are one type of bottom-up approach which uses various sources of information such as crop production surveys and forest monitoring data to estimate the annual CO2 flux at locations covering a study region. Top-down approaches are various types of atmospheric inversion methods which use CO2 concentration measurements from monitoring towers and atmospheric transport models to estimate CO2 flux over a study region. Both methods can also quantify the uncertainty associated with their estimates. Historically, these two approaches have produced estimates that differ considerably. The goal of this work is to construct a statistical model which sensibly combines estimates from the two approaches to produce a new estimate of CO2 flux for our study region. The two approaches have complementary strengths and weaknesses, and our results show that certain aspects of the uncertainty associated with each of the approaches are greatly reduced by combining the methods. Our model is purposefully simple and designed to take the two approaches’ estimates and measures of uncertainty at ‘face value’. Specifically, we use a constrained least-squares approach to appropriately weigh the estimates by the inverse of their variance, and the constraint imposes agreement between the two sources. Our application involves nearly 18,000 flux estimates for the upper midwest United States. The constrained dependencies result in a non-sparse covariance matrix, but computation requires only minutes due to the structure of the model.
- Published
- 2012
40. An investigation of the pineapple express phenomenon via bivariate extreme value theory
- Author
-
Stephan R. Sain, Grant B. Weller, and Daniel Cooley
- Subjects
Statistics and Probability ,Index (economics) ,Ecological Modeling ,Climatology ,Weather Research and Forecasting Model ,Tail dependence ,Environmental science ,Climate model ,Bivariate analysis ,Precipitation ,Marginal distribution ,Extreme value theory - Abstract
The pineapple express (PE) phenomenon is responsible for producing extreme winter precipitation events on the west coast of the United States and Canada. We study regional climate models’ ability to reproduce these events by defining a quantity that captures the spatial extent and intensity of PE events. We use bivariate extreme value theory to model the tail dependence of this quantity as seen in observational data and the Weather Research and Forecasting (WRF) regional climate model driven by reanalysis, and we find tail dependence between the two. To link to synoptic-scale processes, we use daily mean sea-level pressure fields from the reanalysis product to develop a daily “PE index” for extreme precipitation that exhibits tail dependence with our observational quantity. Other models from the North American Regional Climate Change Assessment Program ensemble are used to estimate the future marginal distributions of reanalysis-driven WRF output and observational precipitation. Finally, we employ the fitted tail dependence model to simulate observational precipitation measurements in the future, given output from a future run of WRF. We find evidence of a change in the tail behavior of precipitation from current to future climates, and examination of PE index values of simulated events suggests increases in frequency and intensity of PE precipitation in the future scenario. Copyright © 2012 John Wiley & Sons, Ltd.
- Published
- 2012
41. DIPAK K. DEY, JUN YAN, EDS. Extreme Value Modeling and Risk Analysis: Methods and Applications. Boca Raton: CRC Press
- Author
-
Daniel Cooley
- Subjects
Statistics and Probability ,Risk analysis ,Actuarial science ,General Immunology and Microbiology ,Applied Mathematics ,02 engineering and technology ,General Medicine ,010501 environmental sciences ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,0202 electrical engineering, electronic engineering, information engineering ,Economics ,020201 artificial intelligence & image processing ,General Agricultural and Biological Sciences ,Extreme value theory ,0105 earth and related environmental sciences - Published
- 2017
42. The pairwise beta distribution: A flexible parametric multivariate model for extremes
- Author
-
Richard A. Davis, Philippe Naveau, Daniel Cooley, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Statistics and Probability ,Multivariate statistics ,Multivariate random variable ,Multivariate normal distribution ,01 natural sciences ,010104 statistics & probability ,Multivariate regular variation ,0502 economics and business ,Statistics ,Applied mathematics ,0101 mathematics ,Extreme value theory ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,Beta distribution ,ComputingMilieux_MISCELLANEOUS ,050205 econometrics ,Parametric statistics ,Mathematics ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,Angular measure ,Numerical Analysis ,Spectral measure ,05 social sciences ,Parametric model ,Threshold exceedances ,Generalized extreme value distribution ,Statistics, Probability and Uncertainty - Abstract
We present a new parametric model for the angular measure of a multivariate extreme value distribution. Unlike many parametric models that are limited to the bivariate case, the flexible model can describe the extremes of random vectors of dimension greater than two. The novel construction method relies on a geometric interpretation of the requirements of a valid angular measure. An advantage of this model is that its parameters directly affect the level of dependence between each pair of components of the random vector, and as such the parameters of the model are more interpretable than those of earlier parametric models for multivariate extremes. The model is applied to air quality data and simulated spatial data.
- Published
- 2010
- Full Text
- View/download PDF
43. Spatial Hierarchical Modeling of Precipitation Extremes From a Regional Climate Model
- Author
-
Stephan R. Sain and Daniel Cooley
- Subjects
Statistics and Probability ,Mathematical model ,Applied Mathematics ,Simulation modeling ,Climate change ,Agricultural and Biological Sciences (miscellaneous) ,Hierarchical database model ,Climatology ,Bayesian hierarchical modeling ,Environmental science ,Climate model ,Precipitation ,Statistics, Probability and Uncertainty ,General Agricultural and Biological Sciences ,Extreme value theory ,General Environmental Science - Abstract
The goal of this work is to characterize the extreme precipitation simulated by a regional climate model (RCM) over its spatial domain. For this purpose, we develop a Bayesian hierarchical model. Since extreme value analyses typically only use data considered to be extreme, the hierarchical approach is particularly useful as it sensibly pools the limited data from neighboring locations. We simultaneously model the data from both a control and future run of the RCM which allows for easy inference about projected change. Additionally, this hierarchical model is the first to spatially model the shape parameter which characterizes the nature of the distribution’s tail. Our hierarchical model shows that for the winter season, the RCM indicates a general increase in 100-year precipitation return levels for most of the study region. For the summer season, the RCM surprisingly indicates a significant decrease in the 100-year precipitation return level.
- Published
- 2010
44. Detecting change in UK extreme precipitation using results from the climateprediction.net BBC climate change experiment
- Author
-
Milo Thurston, Stephan R. Sain, Hayley J. Fowler, and Daniel Cooley
- Subjects
Statistics and Probability ,010504 meteorology & atmospheric sciences ,Economics, Econometrics and Finance (miscellaneous) ,0207 environmental engineering ,Climate change ,GCM transcription factors ,02 engineering and technology ,Atmospheric sciences ,01 natural sciences ,13. Climate action ,General Circulation Model ,Generalized extreme value distribution ,Climate model ,BBC Climate Change Experiment ,Precipitation ,Winter season ,020701 environmental engineering ,Engineering (miscellaneous) ,0105 earth and related environmental sciences ,Mathematics - Abstract
We investigate a question posed by policy makers, namely, “when will changes in extreme precipitation due to climate change be detectable?” To answer this question we use climateprediction.net (CPDN) model simulations from the BBC Climate Change Experiment (CCE) over the UK. These provide us with the unique opportunity to compare 1-day extreme precipitation generated from climate altered by observed forcings (time period 1920–2000) and the SRES A1B emissions scenario (time period 2000–2080) (the Scenario) to extreme precipitation generated by a constant climate for year 1920 (the Control) for the HadCM3L General Circulation Model (GCM). We fit non-stationary Generalized Extreme Value (GEV) models to the Scenario output and compare these to stationary GEV models fit to the parallel Control. We define the time of detectable change as the time at which we would reject a hypothesis at the α = 0.05 significance level that the 20-year return level of the two runs is equal. We find that the time of detectable change depends on the season, with most model runs indicating that change to winter extreme precipitation may be detectable by the year 2010, and that change to summer extreme precipitation is not detectable by 2080. We also investigate which climate model parameters affect the weight of the tail of the precipitation distribution and which affect the time of detectable change for the winter season. We find that two climate model parameters have an important effect on the tail weight, and two others seem to affect the time of detection. Importantly, we find that climate model simulated extreme precipitation has a fundamentally different behavior to observations, perhaps due to the negative estimate of the GEV shape parameter, unlike observations which produce a slightly positive (∼0.0–0.2) estimate.
- Published
- 2010
45. A comparison study of extreme precipitation from six different regional climate models via spatial hierarchical modeling
- Author
-
Erin M. Schliep, Stephan R. Sain, Daniel Cooley, and Jennifer A. Hoeting
- Subjects
Statistics and Probability ,010504 meteorology & atmospheric sciences ,Economics, Econometrics and Finance (miscellaneous) ,Statistical model ,01 natural sciences ,Hierarchical database model ,010104 statistics & probability ,13. Climate action ,Climatology ,Statistics ,Spatial ecology ,Generalized extreme value distribution ,Bayesian hierarchical modeling ,Climate model ,Precipitation ,Point estimation ,0101 mathematics ,Engineering (miscellaneous) ,0105 earth and related environmental sciences ,Mathematics - Abstract
We analyze output from six regional climate models (RCMs) via a spatial Bayesian hierarchical model. The primary advantage of this approach is that the statistical model naturally borrows strength across locations via a spatial model on the parameters of the generalized extreme value distribution. This is especially important in this application as the RCM output we analyze have extensive spatial coverage, but have a relatively short temporal record for characterizing extreme behavior. The hierarchical model we employ is also designed to be computationally efficient as we analyze RCM output for nearly 12000 locations. The aim of this analysis is to compare the extreme precipitation as generated by these RCMs. Our results show that, although the RCMs produce similar spatial patterns for the 100-year return level, their characterizations of extreme precipitation are quite different. Additionally, we examine the spatial behavior of the extreme value index and find differing spatial patterns for the point estimates for the RCMs. However, these differences may not be significant given the uncertainty associated with estimating this parameter.
- Published
- 2009
46. Extreme value analysis and the study of climate change
- Author
-
Daniel Cooley
- Subjects
Atmospheric Science ,Global and Planetary Change ,Potential impact ,Basic probability ,Meteorology ,Global warming ,Extreme events ,Econometrics ,Climate change ,Environmental science ,Global change ,Atmospheric temperature ,Extreme value theory - Abstract
In his paper in Climate Monitor, TML Wigley uses basic probability arguments to illustrate how a slowly changing climate could potentially affect the frequency of extreme events. In the time since the paper appeared, there has been increased interest in assessing how weather extremes may be altered by climate change. Much of the work has been conducted using extreme value analysis, which is the branch of statistics developed specifically to characterize extreme events. This commentary discusses the advantages of an EVA approach and reviews some EVA techniques that have been used to describe climate change’s potential impact on extreme phenomena. Additionally, this commentary illustrates basic EVA techniques in an analysis of temperatures for central England. In parallel to Wigley’s analysis, a time-varying EVA analysis is compared to a stationary one, and furthermore, the trend from the EVA analysis is compared to the trend in means.
- Published
- 2009
47. Modelling pairwise dependence of maxima in space
- Author
-
Daniel Cooley, Jean Diebolt, Philippe Naveau, Armelle Guillou, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut de Recherche Mathématique Avancée (IRMA), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Analyse et de Mathématiques Appliquées (LAMA), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Fédération de Recherche Bézout-Université Paris-Est Marne-la-Vallée (UPEM), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Marne-la-Vallée (UPEM)-Fédération de Recherche Bézout-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Statistics and Probability ,010504 meteorology & atmospheric sciences ,General Mathematics ,Copula (linguistics) ,Geostatistics ,01 natural sciences ,Regular grid ,010104 statistics & probability ,[MATH.MATH-ST]Mathematics [math]/Statistics [math.ST] ,Statistics ,Statistics::Methodology ,Statistical physics ,0101 mathematics ,Extreme value theory ,Variogram ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Mathematics ,Applied Mathematics ,Estimator ,[STAT.TH]Statistics [stat]/Statistics Theory [stat.TH] ,Agricultural and Biological Sciences (miscellaneous) ,13. Climate action ,Pairwise comparison ,Statistics, Probability and Uncertainty ,General Agricultural and Biological Sciences ,Maxima - Abstract
We model pairwise dependence of temporal maxima, such as annual maxima of precipitation, that have been recorded in space, either on a regular grid or at irregularly spaced locations. The construction of our estimators stems from the variogram concept. The asymptotic properties of our pairwise dependence estimators are established through properties of empirical processes. The performance of our approach is illustrated by simulations and by the treatment of a real dataset. In addition to bringing new results about the asymptotic behaviour of copula estimators, the latter being linked to first-order variograms, one main advantage of our approach is to propose a simple connection between extreme value theory and geostatistics. Copyright 2009, Oxford University Press.
- Published
- 2009
48. Constrained Predictive Control of Thermal Therapies for Minimum-Time Delivery of Thermal Dose
- Author
-
Daniel Cooley, Mikhail Skliar, Robert B. Roemer, and Dhiraj Arora
- Subjects
Model predictive control ,Temperature control ,Control and Systems Engineering ,Control theory ,Computer science ,System identification ,Constrained optimization ,Specific absorption rate ,Ultrasonic sensor ,Electrical and Electronic Engineering ,Optimal control ,Imaging phantom - Abstract
A method for time-optimal, direct control of thermal dose in thermal therapies is developed and experimentally validated using a focused ultrasound transducer and a phantom patient. State constraint on the maximum allowable temperature in a selected spatial location is imposed to prevent damage to critical normal tissues. A saturation constraint on the ultrasound power is imposed to reflect hardware limitations. It is shown that to achieve the minimum time treatment it is necessary to control the therapy with either saturated ultrasound power or active normal-tissue temperature constraints. The special cases for which the necessary condition are also sufficient for time optimality are also established. The model-based treatment control system is then designed that ensures that the necessary condition for time optimal treatment is satisfied throughout the treatment. During validation experiments, the ultrasound specific absorption rate and thermal response models of the phantom, needed for the operation of the designed treatment control system, were identified using temperature measurements. The performance of the treatment control system during the experiments demonstrates that the proposed approach is effective at delivering the desired thermal dose in a near-minimum time without violating safety constraints imposed in healthy tissues.
- Published
- 2007
49. Bayesian Spatial Modeling of Extreme Precipitation Return Levels
- Author
-
Douglas Nychka, Daniel Cooley, Philippe Naveau, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
- Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,Statistics and Probability ,010504 meteorology & atmospheric sciences ,Markov chain ,Bayesian probability ,Monte Carlo method ,Markov chain Monte Carlo ,01 natural sciences ,010104 statistics & probability ,symbols.namesake ,13. Climate action ,Generalized Pareto distribution ,Climatology ,Statistics ,symbols ,Pareto distribution ,Precipitation ,0101 mathematics ,Statistics, Probability and Uncertainty ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,Extreme value theory ,ComputingMilieux_MISCELLANEOUS ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences ,Mathematics - Abstract
Quantification of precipitation extremes is important for flood planning purposes, and a common measure of extreme events is the r-year return level. We present a method for producing maps of precipitation return levels and uncertainty measures and apply it to a region in Colorado. Separate hierarchical models are constructed for the intensity and the frequency of extreme precipitation events. For intensity, we model daily precipitation above a high threshold at 56 weather stations with the generalized Pareto distribution. For frequency, we model the number of exceedances at the stations as binomial random variables. Both models assume that the regional extreme precipitation is driven by a latent spatial process characterized by geographical and climatological covariates. Effects not fully described by the covariates are captured by spatial structure in the hierarchies. Spatial methods were improved by working in a space with climatological coordinates. Inference is provided by a Markov chain Monte Carlo ...
- Published
- 2007
50. A space-time skew-t model for threshold exceedances
- Author
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Samuel A, Morris, Brian J, Reich, Emeric, Thibaud, and Daniel, Cooley
- Subjects
Air Pollutants ,Models, Statistical ,Ozone ,Normal Distribution ,Bayes Theorem ,United States Environmental Protection Agency ,United States ,Article - Abstract
To assess the compliance of air quality regulations, the Environmental Protection Agency (EPA) must know if a site exceeds a pre-specified level. In the case of ozone, the level for compliance is fixed at 75 parts per billion, which is high, but not extreme at all locations. We present a new space-time model for threshold exceedances based on the skew-t process. Our method incorporates a random partition to permit long-distance asymptotic independence while allowing for sites that are near one another to be asymptotically dependent, and we incorporate thresholding to allow the tails of the data to speak for themselves. We also introduce a transformed AR(1) time-series to allow for temporal dependence. Finally, our model allows for high-dimensional Bayesian inference that is comparable in computation time to traditional geostatistical methods for large data sets. We apply our method to an ozone analysis for July 2005, and find that our model improves over both Gaussian and max-stable methods in terms of predicting exceedances of a high level.
- Published
- 2015
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