Investigating the Causes of Increased Twentieth-Century Fall Precipitation over the Southeastern United States ...

• Main Authors: Bishop, Daniel Alexander, Williams, A. Park, Seager, Richard, Fiore, Arlene M., Cook, Benjamin I., Mankin, Justin S., Singh, Deepti, Smerdon, Jason E., Rao, Mukund Palat
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Columbia University 2019
• Subjects: Mass transfer; Atmospheric circulation; Climatic changes; Precipitation Meteorology; Precipitation variability; Climatology; Nash; North Atlantic
• Online Access: https://dx.doi.org/10.7916/d8-xsbw-mj17; https://academiccommons.columbia.edu/doi/10.7916/d8-xsbw-mj17

Much of the eastern United States experienced increased precipitation over the twentieth century. Characterizing these trends and their causes is critical for assessing future hydroclimate risks. Here, U.S. precipitation trends are analyzed for 1895–2016, revealing that fall precipitation in the southeastern region north of the Gulf of Mexico (SE-Gulf) increased by nearly 40%, primarily increasing after the mid-1900s. Because fall is the climatological dry season in the SE-Gulf and precipitation in other seasons changed insignificantly, the seasonal precipitation cycle diminished substantially. The increase in SE-Gulf fall precipitation was caused by increased southerly moisture transport from the Gulf of Mexico, which was almost entirely driven by stronger winds associated with enhanced anticyclonic circulation west of the North Atlantic subtropical high (NASH) and not by increases in specific humidity. Atmospheric models forced by observed SSTs and fully coupled models forced by historical anthropogenic ...