Date of Award

5-11-2016

Document Type

Restricted Access Thesis

Degree Name

Master of Science in Applied Meteorology

Department

Department of Atmospheric Sciences and Chemistry

Thesis Advisor

Jason M. Cordeira

Committee Member

Eric G. Hoffman

Committee Member

David A. Lavers

Abstract

Atmospheric Rivers (ARs) are long (>2000 km), narrow (< 1000 km) corridors of enhanced vertically integrated water vapor (IWV) and enhanced IWV transport (IVT). The landfall of ARs along the U.S. West Coast have been linked to extreme precipitation and flooding/flash flooding in regions of complex topography. The objective of this study is to investigate the relationship between a 10 water–year (2005–2014) climatology of floods, flash floods, and landfalling ARs. The ARs in this study are defined using IVT following the Rutz et al. (2013) methodology, whereas floods and flash floods are identified by the National Centers for Environmental Information (NCEI) Storm Events Database. The results of this study indicate that landfalling ARs are present on a majority of days that there are floods in northern California. Landfalling ARs are predominantly present on a majority of days that there are flash flood reports during the cold-season (November–March); however, the North American monsoon is present on days that there are flash flood reports during the warm-season (April–October). Two exemplary case studies are provided to illustrate the hydrologic impact of landfalling ARs. The first case study illustrated a flood event that occurred in associated with three landfalling ARs that produced ~800 mm in regions over the Russian River watershed in northern California and the second case study illustrated a flash flood event that occurred in association with a landfalling AR that produced ~225 mm of precipitation in regions over the Santa Ynez watershed in which produced a flash flood over the southern portions of Santa Barbara County in southern California.

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