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Wet bias in GCMs minimize drought, heat wave risk in northeastern United States

Presentation Date
Wednesday, December 13, 2023 at 3:25pm - Wednesday, December 13, 2023 at 3:35pm
MC - 2008 - West



As surface temperatures continue to rise across the globe, the risk for increased droughts and heatwaves rises as well. Many areas of the globe are well known for land-atmosphere coupling, like the Great Plains of the United States, which experiences strong coupling between soil moisture and precipitation. Such regions can experience positive feedbacks between soil moisture and precipitation, where dry soils prevent convective precipitation, leading to further drying. Typically, the Northeastern United States (NEUS) is not considered one of these regions, where historically ample precipitation overcomes any soil moisture deficits. However, it is possible that the 2016 drought in the NEUS suffered a positive feedback induced by strong land-atmosphere coupling. Because of the empirically strong relationship between soil moisture and sensible heating, if general circulation models are too wet (i.e., much more soil moisture than what is realistic), then climate projections will underestimate the risk of droughts and heatwaves in the NEUS. Herein we show that a strong wet bias exists in an ensemble of CMIP6 members and determine that they are underemphasizing the risk for future near-term droughts and heatwaves. Our analysis indicates that by the 2030s, the NEUS can expect 18 more days per summer of excessive sensible heating days and soil conditions 23% drier compared to the historical record.

Funding Program Area(s)