Projected Changes in Extreme Rainfall in New Jersey based on an Ensemble of Downscaled Climate Model Projections



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Ithaca, NY : Cornell University, Northeast Regional Climate Center, Department of Earth and Atmospheric Science


Projections from 46 downscaled climate model simulations were used to project the change in magnitude of extreme rainfall events used in engineering design and planning. A methodology analogous to that used in NOAA Atlas 14 was used to calculate annual average return period precipitation amounts from the model data to allow the computation of future change factors that can be applied to the Atlas 14 precipitation data to simulate future extreme rainfall conditions. Across the state the calculated change factors (CF) are >1 indicating an increase in extreme precipitation amounts. In general, CF values are larger in the northern part of New Jersey and smaller in central NJ and along the coast. Under a high RCP8.5 emissions median CF values range from between 1.10 and 1.30 by the end of the century, indicating a 10-30% increase in extreme precipitation amounts. Under more moderate RCP4.5 emissions, the CFs for 2- and 10-yr annual recurrence interval (ARI) precipitation amounts by the end of the century are typically 1.05-1.15. The CF for 100-yr ARI are more variable ranging from little change (i.e. CF = 1.00) in the vicinity of New York City to larger 20-25% increases in northern NJ.



New Jersey, Rainfall frequencies