Date of Award

January 2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Atmospheric Sciences

First Advisor

Aaron Kennedy

Abstract

Blowing snow and blizzards are wintertime hazards that greatly affect society in the Red River Valley (“RRV”) located between eastern North Dakota and northwestern Minnesota. With poor visibility, snow drifts, and dangerous wind chills, these events can cripple communities as transportation is brought to a standstill. While the underlying mechanisms for blowing snow and ground blizzard initiation are generally understood, there are still many unknowns, including how lofted and blowing snow in horizontal convective rolls affect the thermodynamics and evolution of the atmospheric boundary layer. In the winter of 2019-2020, a research campaign called Blowing Snow Observations at the University of North Dakota: Education through Research (BLOWN-UNDER) was conducted to investigate and better understand the thermodynamics, macrophysics, and microphysics in blowing snow events. The “homerun” event was the 12 February 2020 ground blizzard, which is the focus of this study. Instrumentation used to collect data during the event can be categorized into three main categories: surface in situ, balloon-borne and microphysical, and radar and remote-sensing. This suite of instrumentation allowed for the most comprehensive observations of a ground blizzard ever collected in the RRV. Imagery from a snowflake camera are processed to determine crystal habit and particle size distributions, whose statistics are then used to evaluate the performance of a laser disdrometer. Radar and laser ceilometer data are analyzed to investigate the macrophysics of blowing snow plumes and are used in conjunction with radiosonde data to diagnose boundary layer evolution throughout the blizzard. Lastly, individual instrument analysis is conducted to develop a thorough study of the blizzard’s meteorology as well as assess which instruments are best suited for future blizzard data collection. Results of this study suggest that radar, satellites, radiosondes, and hydrometeor imaging instrumentation are useful for investigating blowing snow and blizzards, whereas lidar and laser disdrometer instrumentation have some limitations in these conditions.

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