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Drivers of Twenty-First Century U.S. Winter Precipitation Trends in CMIP6 Models: A Storyline-Based Approach
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2021
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Source: Journal of Climate, 34(16), 6875-6889
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Journal Title:Journal of Climate
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Description:Climate change during the twenty-first century has the potential to substantially alter geographic patterns of precipitation. However, regional precipitation changes can be very difficult to project, and in some regions, global climate models do not even agree on the sign of the precipitation trend. Since some of this uncertainty is due to internal variability rather than model bias, models cannot be used to narrow the possibilities to a single outcome, but they can usefully quantify the range of plausible outcomes and identify the combination of dynamical drivers that would be likely to produce each. This study uses a storylines approach—a type of regression-based analysis—to identify some of the key dynamical drivers that explain the variance in twenty-first-century U.S. winter precipitation trends across CMIP6 models under the SSP3–7.0 emissions scenario. This analysis shows that the spread in precipitation trends is not primarily driven by differences in modeled climate sensitivity. Key drivers include global-mean surface temperature, but also tropical upper-troposphere temperature, El Niño–Southern Oscillation (ENSO), the Pacific–North America (PNA) pattern, and the east Pacific (EP) dipole (a dipole pattern in geopotential heights over North America’s Pacific coast). Combinations of these drivers can reinforce or cancel to produce various high- or low-impact scenarios for winter precipitation trends in various regions of the United States. For example, the most extreme winter precipitation trends in the southwestern United States result from opposite trends in ENSO and EP, whereas the wettest winter precipitation trends in the midwestern United States result from a combination of strong global warming and a negative PNA trend.
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Source:Journal of Climate, 34(16), 6875-6889
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Rights Information:Other
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Compliance:Submitted
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