The talks will typically take place on Tuesdays at 4:00-5:00pm in Adel Room 164. Please contact Ye Chen if you would like to give a talk or have a question about the colloquium.
Date: Tuesday 1/20 at 4:00-4:50
Speakers: Jaechoul Lee, Associate Professor, NAU
Abstract: Long memory and structural change are common features of environmental time series and pose significant challenges for inference on trends in extremes. Many environmental extreme series exhibit persistent dependence, while changes in policy, monitoring practices, and instrumentation can introduce abrupt shifts that may be confounded with long-memory autocorrelation. Ignoring either feature can lead to misleading conclusions. This talk presents recent methodological developments for analyzing long-term trends in weekly maximum ground-level ozone concentrations across U.S. counties. A long-memory extreme value model is developed using a copula-based framework to capture persistent dependence in extremes. Changepoints are estimated using a genetic algorithm that explicitly accounts for long-memory autocorrelation, reducing the risk of spurious detections. The results demonstrate that incorporating changepoints substantially alters estimated long-term trends in 27.5% of counties and reveals pronounced spatial heterogeneity in both long-term trends and return levels. Overall, this work highlights the importance of jointly modeling long memory, extremes, and structural change in environmental time series analysis.
Date: Tuesday 1/27 at 4:00-4:50
Speakers: Mayank Bakshi, Assistant Professor, NAU
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Date: Tuesday 2/3 at 4:00-4:50
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Date: Tuesday 2/10 at 4:00-4:50
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Date: Tuesday 2/17 at 4:00-4:50
Speakers: Sam Harris
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Date: Tuesday 2/24 at 4:00-4:50
Speakers: Karl C Reger
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Date: Tuesday 3/3 at 4:00-4:50
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Date: Tuesday 3/10 at 4:00-4:50
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Date: Tuesday 3/17 at 4:00-4:50
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Date: Tuesday 3/24 at 4:00-4:50
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Date: Tuesday 3/31 at 4:00-4:50
Speakers: Anders Claesson, Professor, University of Iceland
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Date: Tuesday 4/7 at 4:00-4:50
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Date: Tuesday 4/14 at 4:00-4:50
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Date: Tuesday 4/21 at 4:00-4:50
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Date: Tuesday 4/28 at 4:00-4:50
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