Wind Structure in a Supercell Thunderstorm as Measured by a UHF Wind Profiler

Lehmiller, G. S.; Bluestein, Howard B.; Neiman, Paul J.; Ralph, F. Martin; Feltz, Wayne F.

doi:10.1175/1520-0493(2001)129<1968:wsiast>2.0.co;2

Cited by 17 publications

(7 citation statements)

References 36 publications

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“…4, which is a snapshot of the vertical velocities after 20 min of eruption. The peak updraft velocities of 60 m s -1 in the 'Soputan' case are comparable to the peak convective velocities observed in supercell thunderstorms (Lehmiller et al 2001) or documented volcanic eruptions (Sparks et al 1997). The initial velocity used in these particular modelled eruptions was only 4 m s -1 , so, as for severe thunderstorms, these velocities have been reached through latent heat release, in addition to the warming at the bottom of the eruption column that is present in both atmospheres.…”

Section: Resultssupporting

confidence: 72%

Tall clouds from small eruptions: the sensitivity of eruption height and fine ash content to tropospheric instability

et al. 2009

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A critical factor in successfully monitoring and forecasting volcanic ash dispersion for aviation safety is the height reached by eruption clouds, which is affected by environmental factors, such as wind shear and atmospheric instability. Following earlier work using the Active Tracer High Resolution Atmospheric Model for strong Plinian eruptions, this study considered a range of eruption strengths in different atmospheres. The results suggest that relatively weak volcanic eruptions in the moist tropics can trigger deep convection that transports volcanic material to 15-20 km. For the same volcanic strength there can be *9 km difference between eruption heights in moist tropical and dry subpolar environments (a larger height difference than previously suggested), which appears consistent with observations. These results suggest that eruption intensity should not be estimated from eruption height alone for tropospheric eruptions and also that the average height of volcanic eruptions may increase if the tropical atmospheric belt widens in a changing climate. Ash aggregation is promoted by hydrometeors (particularly liquid A. Tupper (&) Northern Territory Regional Office, Bureau of Meteorology,

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Section: Resultssupporting

confidence: 72%

Tall clouds from small eruptions: the sensitivity of eruption height and fine ash content to tropospheric instability

et al. 2009

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“…Unlike the Truth run and DispTh_NoDA, DispTh_ NoFAT's storm fails to develop a strong updraft [e.g., .50 m s 21 ; note these values are supported by previous observations (e.g., Lehmiller et al 2001)] until after the final data assimilation cycle (Fig. 5c) and fails to develop a strong low-level updraft (e.g., .25 m s 21 below 3 km) at any time (Figs.…”

Section: A Initial Displacement Experiments 1) Perfect Microphysicssupporting

confidence: 78%

Correcting Storm Displacement Errors in Ensembles Using the Feature Alignment Technique (FAT)

Stratman

Potvin

Wicker

2018

Monthly Weather Review

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A goal of Warn-on-Forecast (WoF) is to develop forecasting systems that produce accurate analyses and forecasts of severe weather to be utilized in operational warning settings. Recent WoF-related studies have indicated the need to alleviate storm displacement errors in both analyses and forecasts. A potential solution to reduce these errors is the feature alignment technique (FAT), which mitigates displacement errors between observations and model fields while satisfying constraints. This study merges the FAT with a local ensemble transform Kalman filter (LETKF) and uses observing system simulation experiments (OSSEs) to vet the FAT as a potential alleviator of forecast errors arising from storm displacement errors. An idealized truth run of a supercell on a 250-m grid is used to generate pseudoradar observations, which are assimilated onto a 2-km grid using a 50-member ensemble to produce analyses and forecasts of the supercell. The FAT uses composite reflectivity to generate a 2D field of displacement vectors that is used to align the model variables with the observations prior to each analysis cycle. The FAT is tested by displacing the initial model background fields from the observations or modifying the environmental wind profile to create a storm motion bias in the forecast cycles. The FAT–LETKF performance is evaluated and compared to that of the LETKF alone. The FAT substantially reduces errors in storm intensity, location, and structure during data assimilation and subsequent forecasts. These supercell OSSEs provide the foundation for future experiments with real data and more complex events.

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“…This study explores one possible solution: extended deployments of radar wind profilers to estimate vertical air motions in convective systems. Utilization of the measurements from profiling radars within continental convective thunderstorms has provided unique insights into vertical velocity for decades (e.g., Battan and Theiss 1970;Lehmiller et al 2001), including deeper convection in tropical/monsoonal and so-called break continental regimes (e.g., Cifelli and Rutledge 1994;Williams et al 1995;May andRajopadhyaya 1996, 1999;May et al 2002;Uma and Rao 2009;Heymsfield et al 2010). An obvious challenge is that profiling radars operating in Rayleigh-scattering regimes under precipitating conditions measure a Doppler velocity (air motion and hydrometeor fall speed) and not the ambient air motion directly.…”

Section: Introductionmentioning

confidence: 99%

A Summary of Convective-Core Vertical Velocity Properties Using ARM UHF Wind Profilers in Oklahoma

Giangrande

Collis

Straka

et al. 2013

Journal of Applied Meteorology and Climatology

104

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This study presents a summary of the properties of deep convective updraft and downdraft cores over the central plains of the United States, accomplished using a novel and now-standard Atmospheric Radiation Measurement Program (ARM) scanning mode for a commercial wind-profiler system. A unique profiler-based hydrometeor fall-speed correction method modeled for the convective environment was adopted. Accuracy of the velocity retrievals from this effort is expected to be within 2 m s−1, with minimal bias and base core resolution expected near 1 km. Updraft cores are found to behave with height in reasonable agreement with aircraft observations of previous continental convection, including those of the Thunderstorm Project. Intense updraft cores with magnitudes exceeding 15 m s−1 are routinely observed. Downdraft cores are less frequently observed, with weaker magnitudes than updrafts. Weak, positive correlations are found between updraft intensity (maximum) and updraft diameter length (coefficient r to 0.5 aloft). Negligible correlations are observed for downdraft core lengths and intensity.

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Wind Structure in a Supercell Thunderstorm as Measured by a UHF Wind Profiler

Cited by 17 publications

References 36 publications

Tall clouds from small eruptions: the sensitivity of eruption height and fine ash content to tropospheric instability

Tall clouds from small eruptions: the sensitivity of eruption height and fine ash content to tropospheric instability

Correcting Storm Displacement Errors in Ensembles Using the Feature Alignment Technique (FAT)

A Summary of Convective-Core Vertical Velocity Properties Using ARM UHF Wind Profilers in Oklahoma

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