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Examining the Representation of Extreme Events in 4-km Dynamically Downscaled Simulations within the Southeast U.S.
Citation:
Mallard, M., T. Spero, J. Bowden, A. Jalowska, G. Gray, AND G. Tierney. Examining the Representation of Extreme Events in 4-km Dynamically Downscaled Simulations within the Southeast U.S. 2021 CMAS Conference, Virtual, November 01 - 05, 2021.
Impact/Purpose:
This presentation will present results from high-resolution regional climate simulations, focusing on their ability to represent extreme events.
Description:
As powerful computational resources become more available, finer resolution grid spacing can be used for long-term regional climate simulations. The use of increased spatial resolution to dynamically downscale global climate model output to finer regional domains has the potential to improve representation of extreme events. Presumably, the ability of the regional model to add value increases because mesoscale phenomena and finer-scale topographic and land use/land cover features can be better resolved. However, use of finer scale domains should be investigated to ensure that the chosen physics options are appropriate and that the computational expense is justified by improved results. Here, use of a 4-km domain for simulating extreme events with the Weather Research and Forecasting (WRF) model over the southeastern U.S. is explored and contrasted with results from a 12-km WRF simulation. A global reanalysis dataset, the 0.75° × 0.75° ERA-Interim, is used to drive 3-year simulations over a historical period (2015-2017). A 12-km domain covering the entire contiguous U.S. is run in a configuration similar to previous downscaling work, and then one-way nesting is used to implement a 4-km domain over the Southeast. This small ensemble of 4-km runs compares the use of the Multi-scale Kain–Fritsch scheme to an explicit approach to represent convective processes. These simulations will be compared with observation-based 2-m temperature and precipitation from PRISM (Parameter-elevation Relationships on Independent Slopes Model) data. The ability of these simulations to capture extremes in daily minimum and maximum temperatures, as well as heavy rainfall events, will be assessed.
