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Global Warming Amplifies Heatwaves over Land and Lake Differently

Presentation Date
Monday, January 9, 2023 at 5:00pm - Monday, January 9, 2023 at 6:30pm
Colorado Convention Center - Hall A



Global warming has influenced Great Lakes surface temperature as well as regional climate over the surrounding land in the past; with larger impacts expected in the future (Xue et al. 2022). However, most of regional and global scale climate models still do not represent the Great Lakes realistically. Some of these models (such as Community Earth System Model) treat the lake as land, while others use one-dimensional lake representations which neglect current patterns of lake mixing and stratification in vertical and horizontal dimensions. These limitations will cause large biases in the simulated lake surface temperature by these climate models, which will consequently result in large biases in atmospheric processes, not only over the lakes, but also over the surrounding lands (Wang et al. 2022). To address this gap, this study examines future summertime climate change over the Great Lakes region using the latest version of Weather Research Forecast (WRF) model constrained by satellite derived, high resolution lake surface temperature (lower boundary conditions) and ERA5 reanalysis climatology (lateral boundary conditions). We use a pseudo global warming approach and ensemble members driven by multiple CMIP6 models to understand inter-model variability in future scenarios. Results show that all the 12 WRF runs (11 runs driven by 11 ESMs and one run using their ensemble mean projection) show large summertime warming, with Department Of Energy- Energy Exascale Earth System Model (E3SM) being the warmest (~10 °C increase in mean summer air temperature), and Flexible Global Ocean-Atmosphere-Land System Model (FGOALS) being the coolest (~5 °Cincrease) by end of century under RCP8.5 scenario. The changes in the number of days exceeding the historic 75thand lower percentile of air temperature above lake and land are similar. However, the changes in number of days exceeding the 95th and higher percentile of air temperature above lake is larger than that above land. This is particularly obvious over the southern lakes (Michigan, Erie and Ontario). This indicates that the distribution of extreme heat over the southern lakes would be more than that over the surrounding lands, which can impact regional weather patterns and have adverse impacts on lake ecosystems.

21st Symposium on the Coastal Environment
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