scholarly journals Tornadogenesis in the 12 May 2010 Supercell Thunderstorm Intercepted by VORTEX2 near Clinton, Oklahoma

2018 ◽  
Vol 146 (11) ◽  
pp. 3623-3650 ◽  
Author(s):  
Paul M. Markowski ◽  
Timothy P. Hatlee ◽  
Yvette P. Richardson
Keyword(s):  
Doppler Radar ◽  
Radar Observations ◽  
Low Level ◽  
Time Period ◽  
Supercell Storms ◽  
Supercell Thunderstorm ◽  
Dual Doppler Radar

Abstract The 12 May 2010 supercell thunderstorm intercepted by the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) is analyzed during a time period of strong low-level rotation in which dual-Doppler radar observations were collected. Two different cyclonic vortices are documented. The first vortex was “marginally tornadic” before abruptly weakening, following the development of a descending reflectivity core (DRC) similar to those that have been documented in past studies of supercells. The second vortex rapidly developed immediately north of the DRC shortly after the DRC reached low altitudes, and was associated with a tornado that produced damage near Clinton, Oklahoma. The paper explores the possible roles of the first vortex in triggering the DRC, the DRC in the subsequent initiation of a new updraft pulse on its flank, and the updraft pulse on the development of the second, stronger vortex. The Clinton storm case is, unfortunately, a nice example of the challenges in predicting tornadogenesis within supercell storms even in environments understood to be favorable for tornadoes.

Polarimetric and Dual-Doppler Radar Observations of the Lipscomb County, Texas, Supercell Thunderstorm on 23 May 2002

2009 ◽  
Vol 137 (2) ◽  
pp. 544-561 ◽  
Author(s):  
Jeffrey Frame ◽  
Paul Markowski ◽  
Yvette Richardson ◽  
Jerry Straka ◽  
Joshua Wurman
Keyword(s):  
Doppler Radar ◽  
Polarimetric Radar ◽  
Vorticity Field ◽  
Radar Observations ◽  
Low Level ◽  
Mature Phase ◽  
Numerical Studies ◽  
Vorticity Generation ◽  
Supercell Thunderstorm ◽  
Dual Doppler Radar

Abstract Polarimetric and dual-Doppler observations of a supercell observed by the National Center for Atmospheric Research (NCAR) S-band Polarimetric (SPOL) radar, two Doppler-On-Wheels (DOW) radars, and the Greek XPOL radar on 23 May 2002 during the International H2O Project (IHOP) are presented. The polarimetric radar observations began as the storm organized into a supercell and continued for over an hour while the storm was in its mature phase. The hydrometeor distribution within the mature storm was retrieved using a fuzzy logic hydrometeor classification algorithm. The dual-Doppler radar observations began around the time that the polarimetric radar observations concluded, and they covered the end of the mature phase and much of the dissipation phase of the storm. The dual-Doppler wind syntheses are used to evaluate the importance of the forward-flank outflow in augmenting the horizontal vorticity field near the storm above 400 m. In this case, having a relatively weak low-level mesocyclone, the parcel trajectories and the horizontal vorticity field observed within the forward-flank outflow are not what one would likely expect based on prior numerical studies (having generally stronger low-level mesocyclones) that have emphasized an important dynamical role for forward-flank downdrafts in terms of their horizontal vorticity generation. Instead, the observed trajectories could not be traced from the forward-flank outflow toward the storm’s updraft and the horizontal vorticity vectors within the forward-flank outflow generally did not point (westward) toward the storm’s updraft.

scholarly journals Comparison between Dual-Doppler and EnKF Storm-Scale Wind Analyses: Observing System Simulation Experiments with a Supercell Thunderstorm

2012 ◽  
Vol 140 (12) ◽  
pp. 3972-3991 ◽  
Author(s):  
Corey K. Potvin ◽  
Louis J. Wicker
Keyword(s):  
System Simulation ◽  
Radar Data ◽  
Model Errors ◽  
Radar Observations ◽  
Low Level ◽  
Flow Evolution ◽  
Supercell Thunderstorm ◽  
Wind Retrievals ◽  
Observing System Simulation Experiment ◽  
Microphysical Parameterization

Abstract Kinematical analyses of mobile radar observations are critical to advancing the understanding of supercell thunderstorms. Maximizing the accuracy of these and subsequent dynamical analyses, and appropriately characterizing the uncertainty in ensuing conclusions about storm structure and processes, requires thorough knowledge of the typical errors obtained using different retrieval techniques. This study adopts an observing system simulation experiment (OSSE) framework to explore the errors obtained from ensemble Kalman filter (EnKF) assimilation versus dual-Doppler analysis (DDA) of storm-scale mobile radar data. The radar characteristics and EnKF model errors are varied to explore a range of plausible scenarios. When dual-radar data are assimilated, the EnKF produces substantially better wind retrievals at higher altitudes, where DDAs are more sensitive to unaccounted flow evolution, and in data-sparse regions such as the storm inflow sector. Near the ground, however, the EnKF analyses are comparable to the DDAs when the radar cross-beam angles (CBAs) are poor, and slightly worse than the DDAs when the CBAs are optimal. In the single-radar case, the wind analyses benefit substantially from using finer grid spacing than in the dual-radar case for the objective analysis of radar observations. The analyses generally degrade when only single-radar data are assimilated, particularly when microphysical parameterization or low-level environmental wind errors are introduced. In some instances, this leads to large errors in low-level vorticity stretching and Lagrangian circulation calculations. Nevertheless, the results show that while multiradar observations of supercells are always preferable, judicious use of single-radar EnKF assimilation can yield useful analyses.

scholarly journals Dual-Doppler Radar Observations on Factors Causing Differences in the Structure of Snow Clouds during Winter Monsoon Surges

2004 ◽  
Vol 82 (1) ◽  
pp. 179-206 ◽  
Author(s):  
Hiroyuki YAMADA ◽  
Hiroshi UYEDA ◽  
Katsuhiro KIKUCHI ◽  
Masayuki MAKI ◽  
Koyuru IWANAMI
Keyword(s):  
Doppler Radar ◽  
Winter Monsoon ◽  
Radar Observations ◽  
Dual Doppler Radar

scholarly journals On the Use of Dual-Doppler Radar Measurements for Very Short-Term Wind Power Forecasts

2018 ◽  
Vol 10 (11) ◽  
pp. 1701 ◽  
Author(s):  
Laura Valldecabres ◽  
Nicolai Nygaard ◽  
Luis Vera-Tudela ◽  
Lueder von Bremen ◽  
Martin Kühn
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Power ◽  
Electricity Market ◽  
Doppler Radar ◽  
Short Term ◽  
Radar Observations ◽  
Spatial Coverage ◽  
Probabilistic Forecasts ◽  
Dual Doppler Radar

Very short-term forecasts of wind power provide electricity market participants with extremely valuable information, especially in power systems with high penetration of wind energy. In very short-term horizons, statistical methods based on historical data are frequently used. This paper explores the use of dual-Doppler radar observations of wind speed and direction to derive five-minute ahead deterministic and probabilistic forecasts of wind power. An advection-based technique is introduced, which estimates the predictive densities of wind speed at the target wind turbine. In a case study, the proposed methodology is used to forecast the power generated by seven turbines in the North Sea with a temporal resolution of one minute. The radar-based forecast outperforms the persistence and climatology benchmarks in terms of overall forecasting skill. Results indicate that when a large spatial coverage of the inflow of the wind turbine is available, the proposed methodology is also able to generate reliable density forecasts. Future perspectives on the application of Doppler radar observations for very short-term wind power forecasting are discussed in this paper.

scholarly journals Radar Observations of the Diurnally Forced Offshore Convective Lines along the Southeastern Coast of Taiwan

2005 ◽  
Vol 133 (6) ◽  
pp. 1613-1636 ◽  
Author(s):  
Cheng-Ku Yu ◽  
Ben Jong-Dao Jou
Keyword(s):  
Doppler Radar ◽  
Surface Wind ◽  
Leading Edge ◽  
Heavy Precipitation ◽  
Near Surface ◽  
Radar Observations ◽  
Southeastern Coast ◽  
Low Level ◽  
Narrow Zone ◽  
Offshore Flow

Abstract This study documents offshore convective lines along the southeastern coast of Taiwan, a frequent but poorly understood mesoscale phenomenon that influences coastal weather during the Taiwan mei-yu season. Doppler radar and surface observations were gathered from a specially chosen period (11–15 May 1998) when the offshore convective lines were active off the southeastern coast of Taiwan. These observations were used to show the basic character, structure, and possible formative processes of offshore convective lines. The synoptic environment accompanying these events was found to be relatively undisturbed and featured uniformly prevailing southerly/south-southeasterly winds in the boundary layer with southwesterlies/westerlies aloft. Examination of radar data during the study period indicates that the lines generally occurred ∼10–30 km offshore and were characterized by an elongated narrow zone (∼5–10 km wide) of heavy precipitation. The lines were oriented roughly parallel to the coastline and generally did not move significantly. The intensity of the radar reflectivity associated with the lines exhibited a marked diurnal variation and was closely related to the coastal offshore flow developing at night. Detailed analyses of an event on 14–15 May 1998 further show the important physical link between the offshore flow and the development of the line. The offshore line was found to be located near and immediately ahead of the seaward extent of the offshore flow. Particularly, a very narrow zone (∼2 km) of low-level heavy precipitation (40–45 dBZ) coincided with regions of strong updrafts and convergence, where the prevailing southerly onshore flow encountered the cool offshore flow nearshore. This offshore flow–induced convergence, given a stable thermodynamic condition in the lowest ∼1 km in the inflow region, was a crucial low-level forcing that provided lifting to trigger moist deep convection in this case. The line’s precipitation tilt eastward was confined primarily to the warmer inflow side rather than feeding the offshore flow to the west of the line. No consistent upshear tilt of updrafts throughout the storm layer was observed, which is consistent with the presence of a strong westerly shear in the line’s environment. Both of these observations explain a relatively strong (weak) modification of low-level onshore (offshore) flow by precipitation. Additionally, a combination of surface and Doppler radar observations indicates that the leading edge of the offshore flow moved seaward very slowly at 0.7 m s−1 and possessed a frontal character with notable discontinuities in near-surface wind and temperature (instead of pressure and dewpoint temperature).

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