Science Source

Characterizing Recent Trends in U.S. Heavy Precipitation

Analyzes time series of U.S. daily heavy precipitation (95th percentile) to determine factors responsible for regionality and seasonality in their 1979–2013 trends
Characterizes contiguous U.S. trends, for annual conditions, by increases in precipitation associated with heavy daily events across the northern United States and decreases across the southern United States
Diagnosis of climate simulations (CCSM4 and CAM4) reveals that the evolution of observed sea surface temperatures (SSTs) was a more important factor influencing these trends than boundary condition changes linked to external radiative forcing alone
Finds that since 1979, boundary condition changes linked to external radiative forcing induces widespread, but mostly weak, increases in precipitation associated with heavy daily events
Finds that the evolution of observed sea surface temperatures (SSTs) induces a meridional pattern of northern U.S. increases and southern U.S. decreases as observed, the magnitude of which closely aligns with observed changes, especially over the south and far west
Analysis of model ensemble spread reveals that appreciable 35-yr trends in heavy daily precipitation can occur in the absence of forcing, thereby limiting detection of the weak anthropogenic influence at regional scales

Related Content