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

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.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Atmospheric Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2021

Author dc:creator

• Varcie, Megan Marie

Contributors dc:contributor

• Rauber, Robert M

• Atmospheric Science
• Meteorology
• Microphysics

Statement dc:rights

• Copyright 2021 Megan Marie Varcie

Language dc:language

en

Handle dc:identifier

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

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/110586