Electrical and Kinematic Structure of the Stratiform Precipitation Region Trailing an Oklahoma Squall Line

1991 ◽  
Vol 48 (6) ◽  
pp. 825-842 ◽  
Author(s):  
Terry J. Schuur ◽  
W. David Rust ◽  
Bradley F. Smull ◽  
Thomas C. Marshall
Keyword(s):  
Squall Line ◽  
Kinematic Structure ◽  
Precipitation Region ◽  
Stratiform Precipitation

scholarly journals Incorporating Diagnosed Intercept Parameters and the Graupel Category within the ARPS Cloud Analysis System for the Initialization of Double-Moment Microphysics: Testing with a Squall Line over South China

2016 ◽  
Vol 144 (1) ◽  
pp. 371-392 ◽  
Author(s):  
Yujie Pan ◽  
Ming Xue ◽  
Guoqing Ge
Keyword(s):  
Precipitation Forecast ◽  
Squall Line ◽  
Precipitation Region ◽  
Stratiform Region ◽  
Regional Prediction ◽  
Analysis Scheme ◽  
Stratiform Precipitation ◽  
Double Moment ◽  
Analysis System ◽  
Cloud Analysis

Abstract In this study, a new set of reflectivity equations are introduced into the Advanced Regional Prediction System (ARPS) cloud analysis system. This set of equations incorporates double-moment microphysics information in the analysis by adopting a set of diagnostic relationships between the intercept parameters and the corresponding mass mixing ratios. A reflectivity- and temperature-based graupel classification scheme is also implemented according to a hydrometeor identification (HID) diagram. A squall line that occurred on 23 April 2007 over southern China containing a pronounced trailing stratiform precipitation region is used as a test case to evaluate the impacts of the enhanced cloud analysis scheme. The results show that using the enhanced cloud analysis scheme is able to better capture the characteristics of the squall line in the forecast. The predicted squall line exhibits a wider stratiform region and a more clearly defined transition zone between the leading convection and the trailing stratiform precipitation region agreeing better with observations in general, when using the enhanced cloud analysis together with the two-moment microphysics scheme. The quantitative precipitation forecast skill score is also improved.

scholarly journals Microphysical Characteristics of Squall-Line Stratiform Precipitation and Transition Zones Simulated Using an Ice Particle Property-Evolving Model

2018 ◽  
Vol 146 (3) ◽  
pp. 723-743 ◽  
Author(s):  
Anders A. Jensen ◽  
Jerry Y. Harrington ◽  
Hugh Morrison
Keyword(s):  
Transition Zone ◽  
Maximum Diameter ◽  
Squall Line ◽  
Microphysics Scheme ◽  
Particle Properties ◽  
Precipitation Region ◽  
Convective Region ◽  
Stratiform Precipitation ◽  
Fall Speed ◽  
Microphysical Processes

Abstract A quasi-idealized 3D squall-line case is simulated using a novel bulk microphysics scheme called the Ice-Spheroids Habit Model with Aspect-ratio Evolution (ISHMAEL). In ISHMAEL, the evolution of ice particle properties (e.g., mass, shape, maximum diameter, density, and fall speed) are predicted during vapor growth, sublimation, riming, and melting, allowing ice properties to evolve from various microphysical processes without needing separate unrimed and rimed ice categories. ISHMAEL produces both a transition zone and an enhanced stratiform precipitation region, and ice particle properties are analyzed to determine the characteristics of ice that lead to the development of these squall-line features. Rimed particles advected rearward from the convective region produce the enhanced stratiform precipitation region. The transition zone results from hydrometeor sorting; the evolution of ice particle properties in the convective region leads to fall speeds that favor ice advecting rearward of the transition zone before reaching the melting level, causing a local minimum in precipitation rate and reflectivity there. Sensitivity studies show that the fall speed of ice particles largely determines the location of the enhanced stratiform precipitation region and whether or not a transition zone forms. The representation of microphysical processes, such as rime splintering and aggregation, and ice size distribution shape can impact the mean ice particle fall speeds enough to significantly impact the location of the enhanced stratiform precipitation region and the existence of the transition zone.

Leading and Trailing Anvil Clouds of West African Squall Lines

2011 ◽  
Vol 68 (5) ◽  
pp. 1114-1123 ◽  
Author(s):  
Jasmine Cetrone ◽  
Robert A. Houze
Keyword(s):  
Deep Layer ◽  
Radar Data ◽  
West African ◽  
Squall Line ◽  
Direct Connection ◽  
Precipitation Region ◽  
Cloud Radar ◽  
Squall Lines ◽  
Stratiform Precipitation ◽  
Thick Medium

Abstract The anvil clouds of tropical squall-line systems over West Africa have been examined using cloud radar data and divided into those that appear ahead of the leading convective line and those on the trailing side of the system. The leading anvils are generally higher in altitude than the trailing anvil, likely because the hydrometeors in the leading anvil are directly connected to the convective updraft, while the trailing anvil generally extends out of the lower-topped stratiform precipitation region. When the anvils are subdivided into thick, medium, and thin portions, the thick leading anvil is seen to have systematically higher reflectivity than the thick trailing anvil, suggesting that the leading anvil contains numerous larger ice particles owing to its direct connection to the convective region. As the leading anvil ages and thins, it retains its top. The leading anvil appears to add hydrometeors at the highest altitudes, while the trailing anvil is able to moisten a deep layer of the atmosphere.

scholarly journals Cloud‐Resolving Model Intercomparison of an MC3E Squall Line Case: Part II. Stratiform Precipitation Properties

2019 ◽  
Vol 124 (2) ◽  
pp. 1090-1117 ◽  
Author(s):  
Bin Han ◽  
Jiwen Fan ◽  
Adam Varble ◽  
Hugh Morrison ◽  
Christopher R. Williams ◽  
...  
Keyword(s):  
Squall Line ◽  
Model Intercomparison ◽  
Stratiform Precipitation ◽  
Cloud Resolving Model ◽  
Case Part

Impact of Cloud Microphysics on the Development of Trailing Stratiform Precipitation in a Simulated Squall Line: Comparison of One- and Two-Moment Schemes

2009 ◽  
Vol 137 (3) ◽  
pp. 991-1007 ◽  
Author(s):  
H. Morrison ◽  
G. Thompson ◽  
V. Tatarskii
Keyword(s):  
Size Distribution ◽  
Cloud Microphysics ◽  
Squall Line ◽  
Cloud Droplets ◽  
Microphysics Scheme ◽  
Mixing Ratios ◽  
Stratiform Region ◽  
Stratiform Precipitation ◽  
The One ◽  
Cloud Ice

Abstract A new two-moment cloud microphysics scheme predicting the mixing ratios and number concentrations of five species (i.e., cloud droplets, cloud ice, snow, rain, and graupel) has been implemented into the Weather Research and Forecasting model (WRF). This scheme is used to investigate the formation and evolution of trailing stratiform precipitation in an idealized two-dimensional squall line. Results are compared to those using a one-moment version of the scheme that predicts only the mixing ratios of the species, and diagnoses the number concentrations from the specified size distribution intercept parameter and predicted mixing ratio. The overall structure of the storm is similar using either the one- or two-moment schemes, although there are notable differences. The two-moment (2-M) scheme produces a widespread region of trailing stratiform precipitation within several hours of the storm formation. In contrast, there is negligible trailing stratiform precipitation using the one-moment (1-M) scheme. The primary reason for this difference are reduced rain evaporation rates in 2-M compared to 1-M in the trailing stratiform region, leading directly to greater rain mixing ratios and surface rainfall rates. Second, increased rain evaporation rates in 2-M compared to 1-M in the convective region at midlevels result in weaker convective updraft cells and increased midlevel detrainment and flux of positively buoyant air from the convective into the stratiform region. This flux is in turn associated with a stronger mesoscale updraft in the stratiform region and enhanced ice growth rates. The reduced (increased) rates of rain evaporation in the stratiform (convective) regions in 2-M are associated with differences in the predicted rain size distribution intercept parameter (which was specified as a constant in 1-M) between the two regions. This variability is consistent with surface disdrometer measurements in previous studies that show a rapid decrease of the rain intercept parameter during the transition from convective to stratiform rainfall.

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