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Extreme Precipitation Events As Represented in CMIP5 Models

Paper Reviewed
Janssen, E., Sriver, R.L., Wuebbles, D.J. and Kunkel, K.E. 2016. Seasonal and regional variations in extreme precipitation event frequency using CMIP5. Geophysical Research Letters 43: 5385-5393.

Noting that "understanding how the frequency and intensity of extreme precipitation events are changing is important for regional risk assessments and adaptation planning," Janssen et al. (2016) go on to explain how they used observational data and an ensemble of climate change model experiments -- from the Coupled Model Intercomparison Project Phase 5 (CMIP5) -- to "examine past and potential future seasonal changes in extreme precipitation event frequency over the United States," employing the extreme precipitation index as a metric for extreme precipitation change. And what did this undertaking reveal?

The four U.S. researchers report that the CMIP5 models tend to (1) "overestimate the number of spring events" and (2) "underestimate the number of summer events," noting that (3) "this seasonal shift in the models is amplified in projections." And they further add that (4) "these results provide a basis for evaluating climate model skill in simulating observed seasonality and changes in regional extreme precipitation."

Overall, Janssen et al. thus conclude by indicating that (5) "most models tend to overestimate internal variability in EPI [Extreme Precipitation Index]," with (6) "several key apparent model-data discrepancies." So it's back to the drawing board in an attempt to get all aspects of the subject to better harmonize with each other.

Posted 18 October 2016