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The Life Cycle of a Mesoscale Gravity Wave as Observed by a Network of Doppler Wind Profilers

The Life Cycle of a Mesoscale Gravity Wave as Observed by a Network of Doppler Wind Profilers For the first time, an analysis has been made of the evolving vertical structure of a long-lived mesoscale gravity wave that exerted a strong influence upon the precipitation distribution across a large area. This paper describes this gravity wave system on 14 February 1992, which was observed using a combination of a surface mesonetwork, digital satellite and radar imagery, and several Doppler wind profilers. The resulting vertical structures are compared to the predictions of linear stability theory. Since the signature of the gravity waves in the profiler vertical beam data was often complicated by the presence of precipitation, a kinematic method was developed for estimating the vertical air motions during these periods. The resultant time–height fields show vertical and horizontal winds that are consistent with a gravity wave conceptual model, the microbarograph traces, and the cloud and precipitation patterns. In the early stages of development, a strong vertically erect wave of depression was observed in southwestern Kansas. A few hours later, in central Kansas, a distinct discontinuity had developed at the 4-km level. This phase shift and the vertical motion profiles are both shown to be consistent with linear theory, as well as the notion that the critical level at 5.4 km acted as a nodal surface for a complex ducted wave mode. Precipitation patterns were strongly affected by the waves. According to the profiler analysis, the sharp back edge to the associated rainband was provided by strong low-level subsidence ahead of the wave of depression. The waves and precipitation strengthened in a synergistic fashion—as strong convection developed along the wave, the wave of depression evolved into a wave train in which the leading wave crest eventually dominated over the initial wave of depression. The profiler results reveal the existence of the incipient wave (and other waves) at midlevels several hours before the surface mesonet stations detected the presence of the waves. Thus, an important and unexpected finding from the profiler analysis is that surface microbarograph detection of mesoscale gravity waves may be limited to those waves that primarily affect the lower troposphere. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Monthly Weather Review American Meteorological Society

The Life Cycle of a Mesoscale Gravity Wave as Observed by a Network of Doppler Wind Profilers

Monthly Weather Review , Volume 128 (7) – May 18, 1999

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References (46)

Publisher
American Meteorological Society
Copyright
Copyright © 1999 American Meteorological Society
ISSN
1520-0493
DOI
10.1175/1520-0493(2000)128<2423:TLCOAM>2.0.CO;2
Publisher site
See Article on Publisher Site

Abstract

For the first time, an analysis has been made of the evolving vertical structure of a long-lived mesoscale gravity wave that exerted a strong influence upon the precipitation distribution across a large area. This paper describes this gravity wave system on 14 February 1992, which was observed using a combination of a surface mesonetwork, digital satellite and radar imagery, and several Doppler wind profilers. The resulting vertical structures are compared to the predictions of linear stability theory. Since the signature of the gravity waves in the profiler vertical beam data was often complicated by the presence of precipitation, a kinematic method was developed for estimating the vertical air motions during these periods. The resultant time–height fields show vertical and horizontal winds that are consistent with a gravity wave conceptual model, the microbarograph traces, and the cloud and precipitation patterns. In the early stages of development, a strong vertically erect wave of depression was observed in southwestern Kansas. A few hours later, in central Kansas, a distinct discontinuity had developed at the 4-km level. This phase shift and the vertical motion profiles are both shown to be consistent with linear theory, as well as the notion that the critical level at 5.4 km acted as a nodal surface for a complex ducted wave mode. Precipitation patterns were strongly affected by the waves. According to the profiler analysis, the sharp back edge to the associated rainband was provided by strong low-level subsidence ahead of the wave of depression. The waves and precipitation strengthened in a synergistic fashion—as strong convection developed along the wave, the wave of depression evolved into a wave train in which the leading wave crest eventually dominated over the initial wave of depression. The profiler results reveal the existence of the incipient wave (and other waves) at midlevels several hours before the surface mesonet stations detected the presence of the waves. Thus, an important and unexpected finding from the profiler analysis is that surface microbarograph detection of mesoscale gravity waves may be limited to those waves that primarily affect the lower troposphere.

Journal

Monthly Weather ReviewAmerican Meteorological Society

Published: May 18, 1999

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