High‐resolution projections of 21st century daily precipitation for the contiguous U.S.

Abstract

AbstractChanges in precipitation have the potential to produce wide ranging impacts across human and natural systems. Here precipitation projections from select Atmosphere‐Ocean General Circulation Models and Earth Systems Models participating in Phase 5 of the Coupled Model Intercomparison Project are downscaled to a high‐resolution (0.25° × 0.25°) grid covering the contiguous U.S. to improve spatial and temporal characteristics of the model‐derived projections and derive multiple descriptors of 21st century precipitation climate. Projections for the Northeast, Pacific Northwest, and the high elevations of the Rocky Mountains are characterized by increases in total annual precipitation, with the magnitude depending strongly on the level of radiative forcing. Parts of the southern U.S. are projected to experience moderate precipitation decreases under all forcing scenarios. Increases in total annual precipitation are associated primarily with changes in precipitation intensity during the cold season. Significant precipitation decreases are projected for parts of the southern U.S. in all seasons except autumn and are associated primarily with changes in precipitation occurrence. Many locations in the eastern U.S. are projected to experience longer extreme dry spells and longer extreme wet spells, reflecting an increase in the serial correlation of precipitation. Conversely, many western locations are projected to experience shorter dry spells and wet spells, reflecting a decrease in the serial correlation of precipitation. Most locations are projected to experience an increase in extreme precipitation, reflected in increases in the mean annual single‐day maximum precipitation and the number of heavy (>10 mm) and very heavy (>20 mm) precipitation days.