HUSCAP logo Hokkaido Univ. logo

Hokkaido University Collection of Scholarly and Academic Papers >
Institute of Low Temperature Science >
Peer-reviewed Journal Articles, etc >

Numerical Study of Horizontal Shear Instability Waves along Narrow Cold Frontal Rainbands

Files in This Item:
JAS68-4_878-903.pdf3.36 MBPDFView/Open
Please use this identifier to cite or link to this item:

Title: Numerical Study of Horizontal Shear Instability Waves along Narrow Cold Frontal Rainbands
Authors: Kawashima, Masayuki Browse this author →KAKEN DB
Keywords: Cold fronts
Nonhydrostatic models
Numerical analysis/modeling
Shear structure/flows
Wind shear
Issue Date: Apr-2011
Publisher: American Meteorological Society
Journal Title: Journal of the Atmospheric Sciences
Volume: 68
Issue: 4
Start Page: 878
End Page: 903
Publisher DOI: 10.1175/2010JAS3599.1
Abstract: The effects of variations in low-level ambient vertical shear and horizontal shear on the alongfront variability of narrow cold frontal rainbands (NCFRs) that propagate into neutral and slightly unstable environments are investigated through a series of idealized cloud-resolving simulations. In cases initialized with slightly unstable sounding and weak ambient cross-frontal vertical shears, core-gap structures of precipitation along NCFRs occur that are associated with wavelike disturbances that derive their kinetic energy mainly from the mean local vertical shear and buoyancy. However, over a wide range of environmental conditions, core-gap structures of precipitation occur because of the development of a horizontal shear instability (HSI) wave along the NCFRs. The growth rate and amplitude of the HSI wave decrease significantly as the vertical shear of the ambient cross-front wind is reduced. These decreases are a consequence of the enhancement of the low-level local vertical shear immediately behind the leading edge. The strong local vertical shear acts to damp the vorticity edge wave on the cold air side of the shear zone, thereby suppressing the growth of the HSI wave through the interaction of the two vorticity edge waves. It is also noted that the initial wavelength of the HSI wave increases markedly with increasing horizontal shear. The local vertical shear around the leading edge is shown to damp long HSI waves more strongly than short waves, and the horizontal shear dependency of the wavelength is explained by the decrease in the magnitude of the vertical shear relative to that of the horizontal shear.
Rights: © 2011 American Meteorological Society
Type: article
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 川島 正行

Export metadata:

OAI-PMH ( junii2 , jpcoar_1.0 )

MathJax is now OFF:


 - Hokkaido University