Date of Award

8-1-2022

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Atmospheric and Environmental Sciences

Content Description

1 online resource (vi, 222 pages) : illustrations (some color), color maps

Dissertation/Thesis Chair

Dr. Christopher D Thorncroft

Committee Members

Christopher D Thorncroft, Lance F Bosart, Huang-Hsiung Hsu, Ryan Torn, Brian Tang

Keywords

atmospheric rivers, extremes, future model projections, precipitation, trends, tropical cyclones, Rainstorms, Water vapor transport, Water vapor, Atmospheric, Precipitation (Meteorology), Precipitation forecasting

Subject Categories

Atmospheric Sciences

Abstract

Large-scale extreme precipitation over (1) the mid-Atlantic and Northeast United States and (2) Taiwan is attributed to weather types such as atmospheric river (AR), TC, and extreme integrated vapor transport (IVT). Statistically significant increases in season-total EP day precipitation are seen at many GHCN stations in winter, summer, and fall in the mid-Atlantic and Northeast region, and at certain high-elevation grid points in Taiwan Mei-yu season. During the cold season of winter and spring, the U.S.-based changes come from AR-associated EP days and are associated with strengthened southwesterly winds and IVT either within EP days, in the season mean, or both. This southwesterly flow enhancement occurs along the western and northern sides of an MSLP increase over the eastern U.S., reflective of a strengthening of the Bermuda High on its western flank. In summer, ARs account for a smaller fraction of EP days, but relaxing the extreme IVT and/or AR geometrical criteria results in significant increasing trends in the frequency and precipitation attributed to ARs. This season exhibits significant increases in southerly winds and IVT near and just offshore of the east coast in the season-mean climatology and within EP days – a change likely associated with observed continental MSLP decreases. Fall EP days are influenced more significantly by TCs, which account for a larger fraction of EP days in fall than in any other season. AR-related, TC-related, and extreme IVT-related increases combine to account for the total trend in fall. However, a brief analysis of prior TC influences – defined here as cases where TC-linked moisture contributed to an event no more than 3 days previously – indicates that the majority of the trend may be accounted for by TCs, remote TC influences, or prior TC influences.

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