Jacob Stuivenvolt-Allen

Summary

Global climate models capture large-scale patterns but lack the spatial detail needed for local decision-making about infrastructure, water resources, and extreme events. Regional climate models bridge this gap by downscaling global projections to resolve critical features like mountains, coastlines, and land-atmosphere interactions.

We're expanding NA-CORDEX by downscaling CMIP6 models to 12 km resolution over North America. These high-resolution simulations better capture localized extremes and topographic influences. All data will be openly available and analysis-ready, supporting both research and climate adaptation planning.

Summary

El Niño Southern Oscillation (ENSO) is Earth's most influential climate pattern. Temperature variations in the equatorial Pacific drive not only local circulation but also global temperatures and far-reaching weather impacts through atmospheric "teleconnections.

Climate models project that ENSO will amplify under warming, with larger swings between warm (El Niño) and cold (La Niña) states. My recent Journal of Climate paper explains a potential mechanism behind this amplification.

ENSO is inherently asymmetric—El Niño and La Niña differ in both magnitude and spatial pattern. Our Geophysical Research Letters study shows that atmospheric processes almost entirely account for this asymmetry.

Summary

Explosive cyclones (ECs), defined as extratropical cyclones that experience pressure drops of at least 24 hPa in 24 hours, are impactful weather events in the North Atlantic sector, but year-to-year changes in the frequency and impacts of these storms are sizeable.

To analyze the sources of this interannual variability, we track cases of ECs and dissect them into two spatial groups: those that formed near the east coast of North America (coastal) and those in the North Central Atlantic (high latitude). The frequency of high-latitude ECs is strongly correlated with the North Atlantic Oscillation, a well-known feature, whereas coastal EC frequency is statistically linked with an atmospheric wave-train emanating from the North Pacific in the last 30 years.

Summary

Extreme winds that fueled wildfires across the western U.S. in September 2020 originated from an atmospheric wave train spanning the Pacific. Days earlier, three western Pacific typhoons underwent extratropical transition over Korea within just 12 days—an extremely rare sequence.

Using climate diagnostics and forecast data, we showed these typhoons were critical to the fire weather event. They generated wave activity that amplified the west coast ridge and deepened the Canadian trough, producing the severe frontal system that drove extreme winds across Oregon, Washington, and California.