2009 NOAA Hollings Students
21 July 2009, 1:30 PM - 4:30 PM
National Weather Center, Room 1313
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK
Directions to the NWC (.pdf, 60 kb)
1:30 p.m.
Madison Burnett, University of Missouri
Mentors: Travis Smith, Valliappa Lakshmanan, Cooperative Institute for Mesoscale Meteorological Studies/National Severe Storms Laboratory
“Improvements to Cluster Identification and Tracking in a Circulation Detection Algorithm”
Circulation detection algorithms such as the Mesocyclone Detection Algorithm (MDA) and the Tornado Detection Algorithm (TDA) have been used by National Weather Service forecasters to aid with warning decision-making since the mid-1990s. However, the MDA and TDA are often plagued with misidentified circulations and poor tracking which limit their use as an operational tool. Because of ever-increasing data flow rates from radar upgrades (e.g. WSR-88D “super-resolution”), new technologies (e.g. Phased Array Radar), and the need to quickly analyze circulation signatures in the immense historical WSR-88D data set, NSSL is developing an improved algorithm to identify, diagnose, and track both mesocyclone and tornado size circulations.
The algorithm operates on a field of “azimuthal shear,” which is the rotational derivative of the Doppler radial velocity field. “Clusters” of high azimuthal shear values in both low level (0-3 km above the surface) and mid level (3-7 km above the surface) layers of the storm are identified in the radar data. The clustering and tracking methods were developed on relatively smooth reflectivity fields, but are now being applied to a much noisier azimuthal shear field. This project compares multiple methods of cluster identification and tracking to determine which is best.
1:50 p.m.
Elizabeth Thompson, Valparaiso University
Mentors: Ken Howard, NSSL and Katherine Willingham, CIMMS/NSSL
“Characteristics of Microbursts in Central Arizona”
Summertime thunderstorms in central Arizona associated with the North American Monsoon often become severe and are known to frequently produce damaging microbursts. Occurring in a rapidly growing metropolitan region, these costly and hazardous phenomena pose a critical challenge to forecasters and an extreme concern to local power industries and airport operations.
In order to identify the spatial and temporal characteristics, evolution, and intensity of microbursts in central Arizona, data was utilized from a comprehensive radar network put in place to observe the 2008 convective season in the greater Phoenix area. An S-Band WSR-88D, C-Band TDWR, and C-Band SMART-R were operational throughout the study, offering multiple views of the same storms. Using this new information, microbursts in Central Arizona can be compared to previously documented microbursts in other regions and evaluated in light of the current theoretical understanding of downbursts.
2:10 p.m.
Darren Snively, University of Ohio
Mentors: Richard Thompson, Jeremy Grams, Storm Prediction Center
“Synoptic Environments and Convective Modes Associated with Significant Tornadoes in the Contiguous United States – A Null Case Dataset”
Higher resolution computer modeling and increasingly extensive observation networks have helped meteorologists improve forecasts of significant tornadoes over the past several years. Nevertheless, forecasters continue to rely on recognition of synoptic patterns and associated parameters. R.L. Thompson, J.S. Grams, and J.A. Prentice, through their work in Synoptic Environments and Convective Modes Associated with Significant Tornadoes in the Contiguous United States, have compared “rules of thumb” for significant tornado forecasting using radar images and sounding-derived data including temperature, dew point temperature, wind speed and direction, and pressure at various levels of the atmosphere.
Realizing the atmospheric conditions leading to significant tornadoes is very beneficial, but knowing the differences between a tornadic and non-tornadic event is equally important. In this study, a null case dataset of significant severe weather has been produced. Over one thousand significant wind (65 kt.+) and hail (2”+) reports were collected, none of which were within 120km or 6 hours of a reported tornado. Interpolated RUC model analysis data was gathered for each report to extract the same parameters used in the previous research. This study will show statistical results for the significant wind and hail cases, and compare them to the significant tornado dataset.
2:30 p.m.
Aaron "Ari" Preston, University of Michigan
Mentors: Don MacGorman, NSSL and Terry Schuur, CIMMS/NSSL
“Study of 3-D Total Lightning Activity Relative to Radar-Inferred Storm Parameters”
This study of 3-D total lightning activity as it relates to radar-inferred storm parameters involves making time series plots of flash rates, time/height plots of flash initiations, and VHF source densities relative to times of severe weather. The ultimate goal is to better understand lightning structure and use this knowledge as an operational forecasting tool that can better serve the public's safety.
2:50 - 3 p.m. Break
3 p.m.
Rockwell Schrock, University of Connecticut
Mentor: Daphne Thompson, CIMMS/NSSL
“Creating a Tornado Presentation for Science on a Sphere”
Science on a Sphere (SOS) is an educational tool developed by NOAA for the display of spherical projections of planetary data. The Sphere is often used to give guided presentations that walk the audience through a series of data sets and graphics. This project's goal is to create a presentation to teach the general public about the basics of severe weather forecasting. This presentation takes a case day, May 29, 2008, and separately analyzes four atmospheric components as they relate to severe weather: moisture, instability, lift, and shear. Goals of the presentation include simple explanations and vocabulary, conciseness, an eye-catching aesthetic, and a memorable theme. The ultimate goal is to introduce the audience to seemingly complex topics and, ideally, motivate them to learn more.
3:20 p.m.
Tomas Castellanos, Cornell University
Mentors: Bryan Smith, David Imy, SPC
“A Surface Observing System Measured Severe Convective Wind Analysis, 2005-2008”
The aim of this study is to begin to develop a measured severe convective wind gust database for the contiguous 48 states. SPC archive mesoanalysis data was used to analyze severe convective wind gust report environments, and this data was binned based on season (i.e. warm, cool, transition) and region (i.e. West, Central, Southeast, Northeast) in order to identify atmospheric regimes characteristic to different parts of the country. Additionally, this study compares severe convective wind gust observations between two different observing systems in Oklahoma, (i.e. ASOS/AWOS and the OK Mesonet).
3:40 p.m.
Douglas Crauder, Columbia University
Mentor: Kevin Manross, CIMMS/NSSL
“Examining Polarimetric ZDR Signatures on Isothermal Surfaces Relating to Severe Hail”
NEXRAD, the nation's nation network of weather radars, is getting an upgrade to dual polarization technology beginning within the next 12 months. The upgrade allows radars to be able to transmit in both horizontal and vertical plane. The improved data allows for hydrometeor classification, improved data quality, and the ability to gain more understanding of the microphysical process occurring within storms.
Using one of the new dual polarization parameters ZDR (differential reflectivity), dual polarization radar data can be used to detect a phenomenon in storms known as a ZDR column. These columns are areas of positive differential reflectivity above the 0C isotherm indicating supercooled liquid lifted above the freezing level. In an attempt to correlate this ZDR signature with hail, we are using the output of a multi-radar/multi-sensor version of the Maximum Expected Size of Hail (MESH) algorithm as pseudo-ground truth. By correlating the properties of the columns with respect to multi-radar multi-parameter Maximum Expected Hail Size (MESH), an understanding of the relationship between these columns and severe hail can hopefully be gained.
4 p.m.
Preston Carter, University of Oklahoma
Mentors: Don MacGorman, Harold Brooks, NSSL
“Five Year Lightning Climatology using the Oklahoma Lightning Mapping Array”
This project focuses on lightning data in order to perform a 5 year lightning climatology from 2004 to 2008. The project uses data obtained from the Oklahoma Lightning Mapping Array (LMA). This data was processed in order to determine how many "seconds" of lightning data fall within certain areas that the array covers. This "second" classification is roughly used to determine the number of flashes of lightning in the data set, where one second is equivalent to one flash. The array's domain was divided into a grid and the number of flashes were assigned to different grid points. From this, many different analyses could be performed. These analyses include: diurnal variations, annual variations, and areal variations. Falloff error, based on distance from the LMA, was also considered in detail and will be discussed separately.
4:20 p.m.
Science on A Sphere Tornado Presentation, Atrium
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