Date of Award

December 2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Atmospheric Sciences

First Advisor

David Delene

Abstract

The existence of vertically oriented ice crystals is investigated in winter storms, as observed through remote sensing and analyzed during the NASA Earth Venture Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field campaign field campaign. The primary objective was to determine if a preferred angle of ice crystal orientation could be identified in situ using contemporary airborne sampling instruments. Additionally, the study sought to explore potential correlations between the vertical orientation of ice crystals and electric field anomalies at cloud top, as well as the relationship between crystal orientation and particle concentration. To achieve these objectives, Two-Dimensional Stereo Optical Array Probe (2D-S) Image Data were meticulously analyzed to isolate low aspect ratio ice crystals, including columns, needles, and plates, based on predefined subset parameters. Histograms depicting orientation angles were constructed for each case, comparing results from both horizontal and vertical channels. While some trends were observed—particularly a peak near +21 degrees in the vertical channel—the findings revealed no conclusive evidence of atmospheric vertical orientation due to the absence of null cases. Further, the examination of electric field measurements and particle concentration yielded inconclusive results, with no consistent patterns correlating with the observed orientation. Ultimately, while a preferred angle of orientation was detected, it is postulated that this phenomenon was influenced by external factors, such as airflow around the research aircraft, rather than reflecting the natural state of the ice crystals. This research highlights the need for enhanced in situ electric field measurements and emphasizes the challenges in accurately interpreting ice crystal orientation in dynamic atmospheric conditions.

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