Surface Boundaries of the Southern Plains: Their Role in the Initiation of Convective Storms

Bluestein, Howard B.

doi:10.1007/978-0-933876-68-2_1

Cited by 44 publications

(56 citation statements)

References 111 publications

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“…The lapse rate should be more useful in the analysis applications than the CAPE distribution, since the lapse rate is just the temperature difference between the two levels while the computation of CAPE requires well-resolved profiles of temperature and moisture. Actually some of stability indices, such as K-index and Total-totals index (Bluestein, 1993), reflect the temperature lapse rate between the lowlevel and the middle-level of the troposphere. The existing observational dataset can be reorganized by the lapse rate or related stability indices.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…These variables determine the thermodynamic environments that can be diagnosed by various stability parameters and indices (e.g. Bluestein, 1993;Emanuel, 1994). Using the thermodynamic parameters and stability indices, a number of studies examine the thermodynamic environments for MCSs and rainstorms that occur in various climate regions: the United Stated (Bluestein and Jain, 1985;Houze et al, 1990;Cohen et al, 2007); the Tropics (Barnes and Sieckman, 1984;LeMone et al, 1998); and the subtropical regions (Wang et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

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Dependence of the precipitation intensity in mesoscale convective systems to temperature lapse rate

Takemi

2010

Atmospheric Research

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The dependence of the structure and intensity of precipitation generated within squall lines to environmental temperature lapse rate is investigated by the use of a large set of numerical experiments under idealized model configurations. The lapse rate in a convectively unstable layer is used for the present analysis. The mean precipitation intensity during the simulated period generally increases with the increase in lapse rate, while the maximum precipitation intensity increases with the decrease in lapse rate. The precipitation mean is dependent on the intensity of cold pool resulting from organized convective clouds. In contrast, the precipitation maxima is regulated by relative humidity within the tropospheric lower layer. In an environment with higher lapse rate, a larger amount of CAPE is distributed in a deeper layer of the lower troposphere, which is beneficial for the development and intensification of convection and precipitation. Lapse rate in the troposphere is useful in comparing the characteristics of precipitation produced by mesoscale convective systems that occur in various climate regions of the world and also produced in a future climate under global warming.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dependence of the precipitation intensity in mesoscale convective systems to temperature lapse rate

Takemi

2010

Atmospheric Research

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“…As mentioned above, previous work has indicated a potential for increases to existing horizontal wind convergence atop the surface layer during the AET period, and a resulting enhancement effect on existing convective elements (Jones and Bannon 2002;Murphey et al 2006;Bluestein 2008). To help address this possibility, we consider the mean vertical motion, profile of horizontal wind magnitude, and radar-derived meso-γ scale convergence for the clear-sky, light wind conditions that best display the hallmark signatures of the afternoon-toevening transition.…”

Section: Vertical Motionsmentioning

confidence: 99%

“…Additionally, some studies have indicated that PBL processes during the AET time frame can affect the vigour of existing convection or the initiation of new clouds or storms. Bluestein (2008) noted the common delay in convective initiation along southern USA Plains drylines until near sunset, coining the term "6:00 magic." Simulations described by Jones and Bannon (2002) show that the location and propagation of drylines in the southern Plains are highly dependent on the magnitude and changes of the surface heat flux, with a peak in inversion height and increase in low-level convergence ahead of the boundary occurring at sunset.…”

Section: Introductionmentioning

confidence: 99%

Multi-platform Observations Characterizing the Afternoon-to-Evening Transition of the Planetary Boundary Layer in Northern Alabama, USA

Wingo

Knupp

2014

Boundary-Layer Meteorol

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Observations from the University of Alabama in Huntsville campus and groundbased scanning radar for over 140 total spring, summer, and autumn cases are studied to contribute to the relative scarcity of long-term datasets documenting the afternoon-to-evening transition of the planetary boundary layer. A sunset relative frame of reference is employed, focusing on the period 3 h before to 2 h after astronomical sunset, and several findings are consistent with previous investigations. Fluctuating components of wind and temperature computed from nearly collocated surface, Doppler wind profiler, and vertically pointing Doppler lidar measurements show a consistent decline as turbulence intensity diminishes through the transition. When normalized by their initial values, a pattern emerges: temperature variances decline slowly at first then quite abruptly after about 90 min before sunset. After the temperature variances begin to wane, vertical velocity fluctuations decrease, and the rate of their decay increases as vigorous thermal structures diminish. The fastest decline of the horizontal wind variance occurs after an accelerated vertical wind variance decrease, and the horizontal wind fluctuations display the slowest rate of decrease among these quantities. Near-surface humidity measurements show increases in mean water vapour mixing ratio as a steady rise generally beginning about 80 min prior to sunset. Composites of mean lidar vertical motion show final convective-type towers of upward motion occur about an hour before sunset and are coherent through 800 m (all heights a.g.l.). Lidar vertical motion variance at 195 m decreases by more than an order of magnitude approaching sunset, then remains below 0.01 m 2 s −2 for the rest of the studied time frame. Subtle, but steady, increases in both horizontal wind speed and radar-derived horizontal wind convergence above the surface layer (at 300 m) span the entire 5-h time frame. While the convergence results show a broad range, an increase in the mean is clear and found to be statistically significant. Implications

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“…Tabela 2 -Valores do CAPE e CINE de uma parcela de ar da superfície no período de estudo (em J kg-1) e condições esperadas segundo a classificação de Bluestein (1993).…”

Section: Análise Da Estabilidade E Do Vento Em Altitudeunclassified

Convecção linearmente organizada na área de Petrolina, semi-árido do Nordeste do Brasil: aspectos em meso e grande escala

Silva¹,

Correia

Aragão

et al. 2008

Rev. bras. meteorol.

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RESUMOÉ apresentado um estudo sobre sistemas convectivos linearmente organizados e observados por um radar meteorológico banda-C na região semi-árida do Nordeste do Brasil. São analisados três dias (27 a 29) de março de 1985, com ênfase na investigação do papel desempenhado por fatores locais e de grande escala no desenvolvimento dos sistemas. No cenário de grande escala, a área de cobertura do radar foi influenciada por um cavado de ar superior austral no dia 27 e por um vórtice ciclônico de altos níveis no dia 29. A convergência de umidade próxima à superfície favoreceu a atividade convectiva nos dias 27 e 29, enquanto que divergência de umidade próxima à superfície inibiu a atividade convectiva no dia 28. No cenário de mesoescala, foi observado que o aquecimento diurno é um fator importante para a formação de células convectivas, somando-se a ele o papel determinante da orografia na localização dos ecos. De maneira geral, as imagens de radar mostram os sistemas convectivos linearmente organizados em áreas elevadas e núcleos convectivos intensos envolvidos por uma área de precipitação estratiforme. Os resultados indicam que convergência do fluxo de umidade em grande escala e aquecimento radiativo, são fatores determinantes na evolução e desenvolvimento dos ecos na área de estudo. Palavras-chave: sistema convectivo de mesoescala, linha de instabilidade, vórtice ciclônico de altos níveis, radar meteorológico banda-C ABSTRACT: LINEARLy-ORgANIZED CONVECTION IN THE PETROLINA AREA, SEMI-ARID OF NORTHEASTERN BRAZIL: LARgE AND MESOSCALE ASPECTS A study on linearly organized convective systems observed by a C-band meteorological radar in the semi-arid area of Northeast Brazil is presented. The convective activity during three selected days of 1985 March (27 to 29) was analyzed emphasizing the role played by local and large-scale factors on the development of rain systems. On the large-scale scenario, the covered radar area was influenced by an austral upper-level air trough on March 27th and by an upper-level cyclonic vortex on the 29th. Near-surface moisture convergence favored convective activity on days 27 and 29, while near-surface moisture divergence inhibited convective activity on day 28. On the mesoscale, it was found that diurnal heating was an important factor influencing the formation of the convective cells, while their location was determined mainly by the orography. In general, the radar images show the linearly-organized convective systems over elevated terrain and intense convective cells embedded by a stratiform rain area. The results indicate that large-scale convergence of the moisture flux and radiative heating are determinant factors on the evolution and development of the echoes in the area of study.

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Surface Boundaries of the Southern Plains: Their Role in the Initiation of Convective Storms

Cited by 44 publications

References 111 publications

Dependence of the precipitation intensity in mesoscale convective systems to temperature lapse rate

Dependence of the precipitation intensity in mesoscale convective systems to temperature lapse rate

Multi-platform Observations Characterizing the Afternoon-to-Evening Transition of the Planetary Boundary Layer in Northern Alabama, USA

Convecção linearmente organizada na área de Petrolina, semi-árido do Nordeste do Brasil: aspectos em meso e grande escala

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