View in EDS

Vortex Sheet Sensitivity to Low-Level Vertical Shear and Airmass Temperature Perturbation

Saved in:
Bibliographic Details
Title: Vortex Sheet Sensitivity to Low-Level Vertical Shear and Airmass Temperature Perturbation
Authors: Adam L. Houston, George Limpert
Source: Monthly Weather Review. 150:2423-2441
Publisher Information: American Meteorological Society, 2022.
Publication Year: 2022
Subject Terms: Density currents, Earth Sciences, Mesoscale systems, Mesoscale processes, 01 natural sciences, 0105 earth and related environmental sciences
Description: A theoretical, numerical-modeling-based examination of the sensitivity of vortex sheets along airmass boundaries to the following three characteristics is presented: 1) boundary-normal component of the vertical wind shear, 2) boundary-parallel component of the vertical wind shear, and 3) temperature perturbation within the parent air mass of the boundary. The overall aim of this work is to advance understanding of the sensitivity of micro-α- to meso-γ-scale vortex generation along airmass boundaries to the ambient environment. Density currents are simulated in a 2D domain that does not allow baroclinic generation of near-surface vertical vorticity (ζns) with parameterized latent heating for convection initiated at the associated airmass boundary and Coriolis turned on. Despite the absence of baroclinically generated ζns, with Coriolis turned on and without any boundary-parallel shear, ζns more than two orders of magnitude larger than planetary vorticity is generated along the boundary and located within the cold air. The magnitude of ζns is found to increase with increasing boundary-normal shear with statistically significant intra-experiment separations. Near-surface vertical vorticity ζns is found to scale inversely with boundary-parallel shear with a transition to negative leading-edge ζns in several of the larger boundary-normal shear simulations. An inverse and statistically significant relationship is found between ζns and the temperature perturbation within the parent air mass of the boundary (Δθ), and is a direct consequence of the dependence of boundary propagation speed on Δθ. Significance Statement Research presented in this article aims to contribute to an improved understanding of the environmental controls on the generation of small-scale vortices along airmass boundaries. Vertical shear, both along and across an airmass boundary, as well as temperature of the air mass on the cool side of an airmass boundary are found to regulate the magnitude of near-surface vertical vorticity available to small-scale vortices.
Document Type: Article
File Description: application/pdf
ISSN: 1520-0493
0027-0644
DOI: 10.1175/mwr-d-21-0249.1
Accession Number: edsair.doi.dedup.....9b133e0888018cc9d90e00ef78dd4042
Database: OpenAIRE
Description
Abstract:A theoretical, numerical-modeling-based examination of the sensitivity of vortex sheets along airmass boundaries to the following three characteristics is presented: 1) boundary-normal component of the vertical wind shear, 2) boundary-parallel component of the vertical wind shear, and 3) temperature perturbation within the parent air mass of the boundary. The overall aim of this work is to advance understanding of the sensitivity of micro-α- to meso-γ-scale vortex generation along airmass boundaries to the ambient environment. Density currents are simulated in a 2D domain that does not allow baroclinic generation of near-surface vertical vorticity (ζns) with parameterized latent heating for convection initiated at the associated airmass boundary and Coriolis turned on. Despite the absence of baroclinically generated ζns, with Coriolis turned on and without any boundary-parallel shear, ζns more than two orders of magnitude larger than planetary vorticity is generated along the boundary and located within the cold air. The magnitude of ζns is found to increase with increasing boundary-normal shear with statistically significant intra-experiment separations. Near-surface vertical vorticity ζns is found to scale inversely with boundary-parallel shear with a transition to negative leading-edge ζns in several of the larger boundary-normal shear simulations. An inverse and statistically significant relationship is found between ζns and the temperature perturbation within the parent air mass of the boundary (Δθ), and is a direct consequence of the dependence of boundary propagation speed on Δθ. Significance Statement Research presented in this article aims to contribute to an improved understanding of the environmental controls on the generation of small-scale vortices along airmass boundaries. Vertical shear, both along and across an airmass boundary, as well as temperature of the air mass on the cool side of an airmass boundary are found to regulate the magnitude of near-surface vertical vorticity available to small-scale vortices.
ISSN:15200493
00270644
DOI:10.1175/mwr-d-21-0249.1