Precipitation growth processes in the comma head region of an east coast winter storm

Varcie, Megan Marie

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https://hdl.handle.net/2142/110586 Copy

Description

Title

Precipitation growth processes in the comma head region of an east coast winter storm

Author(s)

Varcie, Megan Marie

Issue Date

2021-04-28

Director of Research (if dissertation) or Advisor (if thesis)

Rauber, Robert M

Department of Study

Atmospheric Sciences

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Atmospheric Science
• Meteorology
• Microphysics

Abstract

On 7 February 2020, a rapidly deepening extratropical cyclone impacted the east coast of the United States, contributing 20-30 cm of snowfall in its comma head region. As part of the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field campaign, precipitation within the comma head region was sampled by two research aircraft, providing a vertical cross-section of in-situ microphysics observations and fine scale radar measurements. The sampled cross-section was stratified vertically by distinct temperature layers and horizontally into a stratiform region on the west side of the cross-section and a region of generating cells at cloud top on the east side. In the stratiform region, precipitation primarily formed near cloud top as polycrystalline crystals. As the P-3 descended through the cloud layer, measurements were consistent with an overall increase in mass and decrease in total number concentration. Interpretations of particle growth were thus consistent with vapor deposition and aggregation, with no evidence of riming as no supercooled liquid water was observed within this region. In the cloud-top generating cell region, new particle habits were observed within each growth layer along with detectable amounts of supercooled liquid water. Measurements were consistent with an overall increase in mass throughout the depth of the cloud, while total number concentrations initially decreased but increased as the P-3 intercepted temperatures warmer than -8°C, with concentrations in excess of 100 L-1 at times. Interpretations of the microphysical data in the generating cell region were thus consistent with vapor depositional growth, riming, and aggregation, as well as secondary ice multiplication via the Hallett-Mossop process in lower altitude flight legs.

Graduation Semester

2021-05

Type of Resource

Thesis

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http://hdl.handle.net/2142/110586

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Copyright 2021 Megan Marie Varcie

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