The Mechanism of Precipitation Formation in Northeastern Colorado Cumulus III. Coordinated Microphysical and Radar Observations and Summary

Dye, J. E.; Knight, Charles; Toutenhoofd, Vim; Cannon, Theodore W.

doi:10.1175/1520-0469(1974)031<2152:tmopfi>2.0.co;2

Cited by 45 publications

(22 citation statements)

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“…In nature, precipitation formation in continental deep convective storms is generally dominated by ice microphysical processes (e.g., Dye et al 1974;Rosenfeld and Ulbrich 2003, among others). Thus, melting of graupel and small hail particles often is responsible for the production of large raindrops.…”

Section: Discussionmentioning

confidence: 99%

The Impact of Size Sorting on the Polarimetric Radar Variables

Kumjian

Ryzhkov

2012

Journal of the Atmospheric Sciences

135

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Differential sedimentation of precipitation occurs because heavier hydrometeors fall faster than lighter ones. Updrafts and vertical wind shear can maintain this otherwise transient size sorting, resulting in prolonged regions of ongoing particle sorting in storms. This study quantifies the impact of size sorting on the S-band polarimetric radar variables (radar reflectivity factor at horizontal polarization Z H , differential reflectivity Z DR , specific differential phase K DP , and the copolar cross-correlation coefficient r hv ). These variables are calculated from output of two idealized bin models: a one-dimensional model of pure raindrop fallout and a two-dimensional rain shaft encountering vertical wind shear. Additionally, errors in the radar variables as simulated by single-, double-, and triple-moment bulk microphysics parameterizations are quantified for the same size sorting scenarios.Size sorting produces regions of sparsely concentrated large drops with a lack of smaller drops, causing Z DR enhancements as large as 1 dB in areas of decreased Z H , often along a Z H gradient. Such areas of enhanced Z DR are offset from those of high Z H and K DP . Illustrative examples of polarimetric radar observations in a variety of precipitation regimes demonstrate the widespread occurrence of size sorting and are consistent with the bin model simulations. Single-moment schemes are incapable of size sorting, leading to large underestimations in Z DR (.2 dB) compared to the bin model solution. Double-moment schemes with a fixed spectral shape parameter produce excessive size sorting by incorrectly increasing the number of large raindrops, overestimating Z DR by 2-3 dB. Three-moment schemes with variable shape parameters better capture the narrowing drop size distribution resulting from size sorting but can underestimate Z DR and overestimate K DP by as much as 20%. Implications for polarimetric radar data assimilation into storm-scale numerical weather prediction models are discussed.

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Section: Discussionmentioning

confidence: 99%

The Impact of Size Sorting on the Polarimetric Radar Variables

Kumjian

Ryzhkov

2012

Journal of the Atmospheric Sciences

135

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“…As recommended by Weisman and Klemp [1984], taking U s = 20 m s −1 led to a favorable dynamical environment for the development of a multicellular storm. This storm had a structure typical of continental thunderstorms in Colorado, characterized by very small droplets that render the collision‐coalescence process inefficient [ Dye et al , 1974; Mansell et al , 2005]. Consequently, supercooling was the fate of the cloud droplets in the updrafts and the formation of rain was dominated by glaciated processes.…”

Section: A 3‐d Multicellular Storm Casementioning

confidence: 99%

Simulation of electrified storms with comparison of the charge structure and lightning efficiency

Barthe

Pinty

2007

J. Geophys. Res.

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[1] An electrification and lightning flash scheme was run in a cloud-resolving model to study the electrical structure of idealized convective storms with several charge separation parameterizations. The electrification of an intense multicellular storm was first simulated. The results confirm the sensitivity of the cloud polarity and lightning flash characteristics to three noninductive charging formulations. Furthermore, it is found that the inductive charging is an efficient mechanism to enhance the lower electric charge, which favors cloud-to-ground flashes. Then, microphysical and electrical budgets were calculated for the convective and stratiform regions of a two-dimensional squall line. The simulation shows that the liquid water content is high enough to generate graupel by riming. Thus the noninductive separation process is efficient to charge the stratiform plume as well, and lightning flashes can be triggered. Finally, the application of various noninductive charging schemes to several convective storms showed the storm electrification variability, which heavily depends on the cloud dynamics and microphysics. The study reveals some remarkable features concerning the charge structure and the cloud-to-ground flash polarity.Citation: Barthe, C., and J.-P. Pinty (2007), Simulation of electrified storms with comparison of the charge structure and lightning efficiency,

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“…Rather, the purpose is to test the performance of several optimization algorithms on mixed rain and hail events, precipitation that is common in the high plains during the warm season (Dye et al 1974) and is extremely challenging for radar quantitative precipitation estimation (QPE). Rather, the purpose is to test the performance of several optimization algorithms on mixed rain and hail events, precipitation that is common in the high plains during the warm season (Dye et al 1974) and is extremely challenging for radar quantitative precipitation estimation (QPE).…”

Section: Introductionmentioning

confidence: 99%

A New Dual-Polarization Radar Rainfall Algorithm: Application in Colorado Precipitation Events

Cifelli

Chandrasekar

Lim

et al. 2011

Journal of Atmospheric and Oceanic Technology

179

101

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The efficacy of dual-polarization radar for quantitative precipitation estimation (QPE) has been demonstrated in a number of previous studies. Specifically, rainfall retrievals using combinations of reflectivity (Z h ), differential reflectivity (Z dr ), and specific differential phase (K dp ) have advantages over traditional Z-R methods because more information about the drop size distribution (DSD) and hydrometeor type are available. In addition, dual-polarization-based rain-rate estimators can better account for the presence of ice in the sampling volume.An important issue in dual-polarization rainfall estimation is determining which method to employ for a given set of polarimetric observables. For example, under what circumstances does differential phase information provide superior rain estimates relative to methods using reflectivity and differential reflectivity? At Colorado State University (CSU), an optimization algorithm has been developed and used for a number of years to estimate rainfall based on thresholds of Z h , Z dr , and K dp . Although the algorithm has demonstrated robust performance in both tropical and midlatitude environments, results have shown that the retrieval is sensitive to the selection of the fixed thresholds.In this study, a new rainfall algorithm is developed using hydrometeor identification (HID) to guide the choice of the particular rainfall estimation algorithm. A separate HID algorithm has been developed primarily to guide the rainfall application with the hydrometeor classes, namely, all rain, mixed precipitation, and all ice.Both the data collected from the S-band Colorado State University-University of Chicago-Illinois State Water Survey (CSU-CHILL) radar and a network of rain gauges are used to evaluate the performance of the new algorithm in mixed rain and hail in Colorado. The evaluation is also performed using an algorithm similar to the one developed for the Joint Polarization Experiment (JPOLE). Results show that the new CSU HID-based algorithm provides good performance for the Colorado case studies presented here.

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The Mechanism of Precipitation Formation in Northeastern Colorado Cumulus III. Coordinated Microphysical and Radar Observations and Summary

Cited by 45 publications

References 0 publications

The Impact of Size Sorting on the Polarimetric Radar Variables

The Impact of Size Sorting on the Polarimetric Radar Variables

Simulation of electrified storms with comparison of the charge structure and lightning efficiency

A New Dual-Polarization Radar Rainfall Algorithm: Application in Colorado Precipitation Events

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