Atmospheric Rivers: Genesis, Representation, and Structure

• Main Author: Kim, Sol
• Other Authors: Chiang, John C. H.
• Format: Thesis
• Language: English
• Published: eScholarship, University of California 2023
• Subjects: Physical geography; Arctic; Pacific
• Online Access: https://escholarship.org/uc/item/25z985cj

The goal of this dissertation is to advance atmospheric river (AR) research in 3 distinct areas: (i) genesis of ARs, (ii) model representation of ARs, and (iii) the impact of AR core structure on landfalling precipitation.In Chapter 2, the range of synoptic patterns that north Pacific landfalling ARs form under are objectively identified using genesis day 500 hPa geopotential height anomalies in a self- organizing map (SOM). The SOM arranges the synoptic patterns to differentiate between two groups of climate modes - the first group with ENSO (El Nin ̃o Southern Oscillation), PDO (Pacific Decadal Oscillation), PNA (Pacific North American) and NP (North Pacific index) and the second group with AO (Arctic Oscillation), EPO (East Pacific Oscillation), and WPO (West Pacific Oscillation). These two groups have their positive and negative modes organized in opposite corners of the SOM. The ARs produced in each of the syn- optic patterns have distinct lifecycle characteristics (such as genesis and landfall location, duration, velocity, meridional/zonal movement) and precipitation impacts (magnitude and spatial distribution). The conditions that favor AR trajectories closer to the tropics tend to produce higher amounts of precipitation. The large-scale circulation associated with AR genesis shows a close relationship between the genesis location and the location and intensity of the upper level jet in the west/central pacific as well as anomalous, low level southwesterly winds in the east pacific. Chapter 3 focuses on evaluating The Energy Exascale Earth System Model (E3SM) version v1.0 for its ability to represent ARs, which play significant roles in water vapor transport and precipitation. The E3SM Project is an ongoing, state-of-the-science Earth system modeling, simulation, and prediction project developed by the U.S. Department of Energy (DOE). With an emphasis on supporting DOE’s energy mission, understanding and quantifying how well the model simulates water cycle processes is of particular importance. The ...