Type
Text
Type
Dissertation
Advisor
Colle, Brian A. | Chang, Edmund | Zhang, Minghua | Yuter, Sandra E. | Schultz, David M.
Date
2017-05-01
Keywords
Extratropical cyclones, Snowbands | Meteorology -- Atmospheric sciences
Department
Department of Marine and Atmospheric Science
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/77749
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Mesoscale precipitation bands within Northeast U.S. (NEUS) winter storms result in heterogeneous spatial and temporal snowfall. Several studies have provided analysis of snowbands focusing on larger, meso-α scale bands with lengths (L) > 200 km known as single bands. NEUS winter storms can also exhibit multiple bands with meso-β scale (L < 200 km) and similar spatial orientation and when ≥ 3 occur are termed multi-bands; however, the genesis and evolution of multi-bands is less well understood. Unlike single bands, there is no multi-bands climatological study. In addition, there has been little detailed thermodynamic analysis of snowbands. This dissertation utilizes radar observations, reanalyses, and high-resolution model simulations to explore the thermodynamic evolution of single and multi-bands. Bands are identified within 20 cool season (October–April) NEUS storms. The 110-case dataset was classified using a combination of automated and manual methods into: single band only (SINGLE), multi-bands only (MULTI), both single and multi-bands (BOTH), and non-banded (NONE). Multi-bands occur with the presence of a single band in 55.4% of times used in this study, without the presence of a single band 18.1% of the time, and precipitation exhibits no banded characteristics 23.8% of the time. Most MULTI events occur in the northeast quadrant of a developing cyclone poleward of weak-midlevel forcing along a warm front, whereas multi-bands associated with BOTH events mostly occur in the northwest quadrant of mature cyclones associated with strong mid-level frontogenesis and conditional symmetric instability. The non-banded precipitation associated with NONE events occur in the eastern quadrants of developing and mature cyclones lacking mid-level forcing to concentrate the precipitation into bands. A high-resolution mesoscale model is used to explore the evolution of single and multi-bands based on two case studies, one of a single band and one of multi-bands. The multi-bands form in response to intermittent mid-level frontogenetical forcing in a conditionally unstable environment. The bands within their genesis location southeast of the single band move northwest towards the single band by 700-hPa steering flow. This allows for the formation of new multi-bands within the genesis region, unlike the single band that remains fixed to a 700-hPa frontogenesis maximum. Latent heating within the band is shown to increase the intensity and duration of single and multi-bands through decreased geopotential height below the heating maximum that leads to increased convergence within the band. | Mesoscale precipitation bands within Northeast U.S. (NEUS) winter storms result in heterogeneous spatial and temporal snowfall. Several studies have provided analysis of snowbands focusing on larger, meso-α scale bands with lengths (L) > 200 km known as single bands. NEUS winter storms can also exhibit multiple bands with meso-β scale (L < 200 km) and similar spatial orientation and when ≥ 3 occur are termed multi-bands; however, the genesis and evolution of multi-bands is less well understood. Unlike single bands, there is no multi-bands climatological study. In addition, there has been little detailed thermodynamic analysis of snowbands. This dissertation utilizes radar observations, reanalyses, and high-resolution model simulations to explore the thermodynamic evolution of single and multi-bands. Bands are identified within 20 cool season (October–April) NEUS storms. The 110-case dataset was classified using a combination of automated and manual methods into: single band only (SINGLE), multi-bands only (MULTI), both single and multi-bands (BOTH), and non-banded (NONE). Multi-bands occur with the presence of a single band in 55.4% of times used in this study, without the presence of a single band 18.1% of the time, and precipitation exhibits no banded characteristics 23.8% of the time. Most MULTI events occur in the northeast quadrant of a developing cyclone poleward of weak-midlevel forcing along a warm front, whereas multi-bands associated with BOTH events mostly occur in the northwest quadrant of mature cyclones associated with strong mid-level frontogenesis and conditional symmetric instability. The non-banded precipitation associated with NONE events occur in the eastern quadrants of developing and mature cyclones lacking mid-level forcing to concentrate the precipitation into bands. A high-resolution mesoscale model is used to explore the evolution of single and multi-bands based on two case studies, one of a single band and one of multi-bands. The multi-bands form in response to intermittent mid-level frontogenetical forcing in a conditionally unstable environment. The bands within their genesis location southeast of the single band move northwest towards the single band by 700-hPa steering flow. This allows for the formation of new multi-bands within the genesis region, unlike the single band that remains fixed to a 700-hPa frontogenesis maximum. Latent heating within the band is shown to increase the intensity and duration of single and multi-bands through decreased geopotential height below the heating maximum that leads to increased convergence within the band. | 259 pages
Recommended Citation
Ganetis, Sara Anne, "The Role of Thermodynamic Processes in the Evolution of Single and Multi-banding within Winter Storms" (2017). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 3532.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/3532