LEE-SIDE FRONTOGENESIS IN THE ROCKY MOUNTAINSSource: Monthly Weather Review:;1961:;volume( 089 ):;issue: 005::page 163Author:CARLSON, TOBY N.
DOI: 10.1175/1520-0493(1961)089<0163:LFITRM>2.0.CO;2Publisher: American Meteorological Society
Abstract: The development and motion of fronts associated with lee-side troughs on large mountain barriers has been investigated. These fronts differ from ordinary cold fronts in their horizontal temperature field, which is characterized by a sinusoidal thermal ridge. The thermal ridge intensifies, while remaining stationary with respect to the mountains, and moves eastward upon the approach of a Pacific cold front. An equation is derived, showing that changes in the thermal pattern can be described by changes in a potential thermal vorticity equation, which consists of three terms: (1) one representing an advection of the potential thermal vorticity by the 500-mb. wind; (2) one representing the advection of 500-mb. absolute vorticity by the thermal wind; and (3) a purely orographic term. An idealized sinusoidal model of the thickness pattern is used in conjunction with the prognostic equation to explain the development and motion of lee-side thermal ridges. Actual examples from synoptic maps are chosen to corroborate the theory. The conclusions are: (1) the thermal ridge will develop when the surface flow is such as to produce large-scale descent on the lee slopes of the mountains; (2) no thermal ridging will appear when the 500-mb. ridge lies east of the lee slopes; (3) thermal ridging will appear with the approach of a 500-mb. ridge from the west; and (4) the thermal ridge will move eastward upon the passage of the 500-mb. ridge.
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contributor author | CARLSON, TOBY N. | |
date accessioned | 2017-06-09T15:56:48Z | |
date available | 2017-06-09T15:56:48Z | |
date copyright | 1961/05/01 | |
date issued | 1961 | |
identifier issn | 0027-0644 | |
identifier other | ams-57204.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4197515 | |
description abstract | The development and motion of fronts associated with lee-side troughs on large mountain barriers has been investigated. These fronts differ from ordinary cold fronts in their horizontal temperature field, which is characterized by a sinusoidal thermal ridge. The thermal ridge intensifies, while remaining stationary with respect to the mountains, and moves eastward upon the approach of a Pacific cold front. An equation is derived, showing that changes in the thermal pattern can be described by changes in a potential thermal vorticity equation, which consists of three terms: (1) one representing an advection of the potential thermal vorticity by the 500-mb. wind; (2) one representing the advection of 500-mb. absolute vorticity by the thermal wind; and (3) a purely orographic term. An idealized sinusoidal model of the thickness pattern is used in conjunction with the prognostic equation to explain the development and motion of lee-side thermal ridges. Actual examples from synoptic maps are chosen to corroborate the theory. The conclusions are: (1) the thermal ridge will develop when the surface flow is such as to produce large-scale descent on the lee slopes of the mountains; (2) no thermal ridging will appear when the 500-mb. ridge lies east of the lee slopes; (3) thermal ridging will appear with the approach of a 500-mb. ridge from the west; and (4) the thermal ridge will move eastward upon the passage of the 500-mb. ridge. | |
publisher | American Meteorological Society | |
title | LEE-SIDE FRONTOGENESIS IN THE ROCKY MOUNTAINS | |
type | Journal Paper | |
journal volume | 89 | |
journal issue | 5 | |
journal title | Monthly Weather Review | |
identifier doi | 10.1175/1520-0493(1961)089<0163:LFITRM>2.0.CO;2 | |
journal fristpage | 163 | |
journal lastpage | 172 | |
tree | Monthly Weather Review:;1961:;volume( 089 ):;issue: 005 | |
contenttype | Fulltext |