2010 NWC
REU Papers
Assessing Climate Change
Impacts on the Blue River Basin of Oklahoma [PDF]
Christopher Bednarczyk
Mentors: Yang Hong (OU CEES)
A 16 GCM ensemble was used to assess the future climate of Oklahoma
and its Blue River Basin under three IPCC emissions scenarios. Output
from the models was then applied to a monthly water balance model to
predict changes in the hydrologic cycle. By the end of the century
ensemble median warming is predicted to be 2.2 to 4.6 °C for the
state depending on the scenario. Precipitation trends depended on the
emissions scenario, with the state experiencing almost no annual change.
The Blue River Basin is expected to receive slightly more precipitation
under the lower emissions scenario and less under the higher scenario.
Change in temperature along with little change in precipitation led
to predicted increase in both potential evapotranspiration and actual
evapotranspiration. Soil moisture and runoff are both expected to decrease
significantly. Runoff changes by 2100 ranged from ensemble mean of
-9.6% for the lower emission scenario to -29.8% for the higher.
Evaluating High-Resolution NWP
Forecasts of the Nocturnal Low Level Jet for Improving Wind Power
Forecasts [PDF]
Jeffrey Deppa
Mentors: Richard Carpenter and Brent Shaw (WDT, Inc.)
The Nocturnal Low Level Jet (NLLJ) is a significant contributor to
overnight wind power production in the Southern Great Plans. This region
of the United States is expecting wind farm growth over the coming
decades and therefore it is important to better understand how to forecast
wind energy, and hence forecast the strength and location of the NLLJ.
The Weather Research and Forecasting Model (WRF) is one tool that can
be used for forecasting winds. This study investigates performance
of a real-time, high-resolution (3-km grid spacing) configuration of
the WRF for several NLLJ cases in southwest Oklahoma. Forecast location
and intensity of the NLLJ and its interaction with moderate terrain
features around the Blue Canyon Wind Farm, particularly the Wichita
Mountains and Slick Hills, were evaluated. These model forecasts also
provide insight into the relationship between NLLJ behavior as a function
of wind magnitude and atmospheric stability. The study finds that errors
in model forecasted boundary layer stability coupled with NLLJ terrain
interactions could be the reason for wind forecast errors at Blue Canyon.
Evaluation of NWS Storm-Based
Warnings Using Gridded Products [PDF]
Todd Ferebee
Mentors: Kiel Ortega (OU CIMMS) and Kevin Scharfenberg (NOAA NWS
OCWWS)
In 2008, the National Weather Service began issuing storm-based polygon
warnings instead of county warnings. Only one severe hail, wind, or
tornado report is needed to verify an entire warning polygon. Few severe
weather reports in the warning, and in turn for the storm which prompted
the warning, makes difficult to determine the spatial extent of severe
weather for a particular storm. Since 2006, the Severe Hazards Analysis
and Verification Experiment (SHAVE) has been collecting severe weather
reports at temporal and spatial resolutions much higher than those
available in Storm Data. The National Severe Storms Laboratory
(NSSL) produces several severe weather products, such as reflectivities
at different isotherms and estimated hail size, on a grid for the entire
contiguous United States. These grids could provide for synthetic verification
of severe weather especially for the spatial extent of severe weather.
This study will investigate how well the grids perform in determining
where severe hail fell by using high resolution SHAVE reports. Discussed
for applications of such grids for warning verification and improvement
will also be included.
Updraft Helicity as a Forecast
Parameter [PDF]
Stacey Hitchcock
Mentors: Patrick Marsh (OU SOM), Harold Brooks (NOAA NSSL), and Charles
A. Doswell III (OU CIMMS)
Improved science and technology has created the opportunity to explore
the impacts of different model diagnostic fields as indicators
of convection developed in highresolution numerical models.
Indication of the success of different diagnostic fields has
been discussed (Kain et al. 2008, Sobash et al. 2008). Updraft helicity
(UH) has shown a particular ability to identify supercell-like
structure in convection allowing model observed locations.
UH will be examined to determine the best integration layer over which to calculate UH.
Output of updraft helicity over different layers from the convection
allowing 4-km National Severe Storms Laboratory- Weather Research
and Forecasting Radar (NSSLWRF) Advanced Research WRF (ARW)
from the Spring Experiment 2008 was compared to Storm Prediction
Center (SPC) storm reports using contingency tables. Verification
measures (Probability of Detection, False Alarm Ratio, Critical Success Index,
bias) were calculated from the contingency tables and used to create
several visual comparisons. These include Relative Operating
Characteristic curves (ROC) (Mason 1982), and Performance
Diagrams (Roebber 2008), as a comparison of different depth’s success as a forecast parameter.
Spatial Analysis of Tornado Vulnerability
Trends in Oklahoma and Northern Texas [PDF]
Eric Hout
Mentors: May Yuan, John MacIntosh, and Chris Weaver (OU CSA)
Determination of effective ways to reduce vulnerability from tornadoes
is one of the fundamental drivers for tornado research. This study
analyzes spatial vulnerability in the context of past tornado events
with aims to enhance the understanding of tornado casualties in Oklahoma
and Northern Texas. Many previous studies on tornado vulnerability
have provided insight on how individual factors influence overall social
and spatial vulnerability. However, few studies have been conducted
to evaluate the aggregated effect on vulnerability when these factors
coincide. Additionally, a definition of vulnerability has been absent
from the meteorological literature. Thus, to provide a more comprehensive
view of vulnerability, this study proposes a mathematical definition
for spatial vulnerability, and then uses tornado casualty data from
1950 through 2009 to calculate vulnerability on a county level for
seven time periods. Overall vulnerability trends are then calculated
and visualized by averaging changes and by k-means clustering. This
study shows the existence of spatial patterns in vulnerability between
counties both when analyzing each individual F-scale and when all F-scales
are combined. These spatial patterns are likely caused by the existence
of multiple variables working together.
Radar-Disdrometer Comparison to
Reveal Attenuation Effects on CASA Radar Data [PDF]
Christopher Kerr
Mentors: Guifu Zhang (OU SOM)
X-band radar provides a high resolution image at the cost of significant
attenuation. This is due to the X-band's short wavelength.
In this study, a two dimensional video disdrometer (2DVD) was deployed
to the center of a triangle formed by three CASA dual-polarization
X-band radars. The CASA radars provide measurements of reflectivity,
differential reflectivity, specific differential phase, and copolar
cross-correlation coefficient of precipitation. Using drop size distributions
obtained from the 2DVD, the radar variables are calculated and treated
as the ground truth. The radar and disdrometer measurements are compared
to reveal discrepancies. Biases and errors are calculated, and possible
causes are investigated. These results can be used to further minimize
the attenuation obstacle in X-band radar.
An Analysis of Southern U.S.
Ice Storm Frequency From 2000-2009 [PDF]
Carly Kovacik
Mentors: Mark Shafer and James Hocker (OCS)
The Southern Climate Impacts Planning Program (SCIPP) is a climate
research program that focuses on helping the
public improve planning for weather and climate-related disasters.
SCIPP focuses on the high frequency of
hazardous weather events, including extremes in precipitation. Over
the past several years, SCIPP has speculated
that there has been an increase in the number of ice storms within
the region each winter. This paper analyzes trends
in ice storm frequency and intensity for the years 2000-2009 using
data from the National Climatic Data Center’s
Storm Events and Storm Data datasets. For this period of study, it
was found that an ice storm maximum stretches
from southwestern Texas through Oklahoma, northwestern Arkansas, southeastern
Kansas and central Missouri. It
was also found that there is no consistent trend associated with the
number of ice storms, the ice thickness values of
recorded ice storms, or the number of ice storm catastrophes over the
last ten years. Ice storm frequency was also
briefly compared to atmospheric signals and El Nino-Southern Oscillation
(ENSO) events. This project also
identified discrepancies in ice storm reporting across National Weather
Service office boundaries as evidenced
through Geographic Information Systems mapping. This project provides
preliminary results that can be incorporated
into more extensive studies to create national criteria for documenting
ice storms.
Verifying Model Forecasts of Arctic
Fronts in Advance of Winter Storms in the Southern Plains [PDF]
Willliam E. Leatham, IV
Mentors: Patrick Burke and Andrew Taylor (NOAA NWS Norman)
Arctic fronts and associated freezing line positions are of concern in winter
storm forecasting. In the southern Great Plains of the United States the
arrival of shallow arctic air plays a major role in the development of severe
ice storms. At other times, the cold air becomes deep enough to support snowstorms
and even blizzard conditions. Forecasters' providing at least twelve to
twenty-four hour advanced warning allows the public and other groups time
to prepare for these potentially dangerous events. Therefore, determining
how operational forecast models perform in these situations is crucial to
improving forecast accuracy and increasing our understanding of shallow cold
air. This paper compares the observed surface freezing line and cold front
location with model forecasts of both these features during the twenty-four
hour period leading up to the onset of four winter storms. The model forecasts
tend to move arctic fronts southward much too slowly. This has strong implications
for the southward extent of winter storm warnings based on model forecasts,
and their associated lead time.
Public Response to the 10 May 2010
Norman, Oklahoma Tornado [PDF]
Sarah Stalker
Mentors: Heather Lazrus (OU SSWIM), Kristin Kulhman (OU CIMMS), Randy Peppler
(OU CIMMS), and Kim Klockow (OCS)
The purpose of this project is to gather initial actions and reactions from
the public in response to the 10 May 2010 Norman, Oklahoma tornado. This
is done in support of the National Severe Storms Laboratory's Warn-on-Forecast
project for severe thunderstorm, tornado, and flash flood events. The tools
and products that will be developed as part of the project are needed to
improve warning for both the public and community stakeholders i.e. emergency
managers, hospitals, and schools. This research study consisted of formally
interviewing 6 individuals impacted by the May 10 storm and analyzing their responses.
The majority of the interviewees did not feel any direct threat from the
tornado during the early stages of storm development and advisories. Interestingly,
with a longer lead-time promised by Warn-on-Forecast, most said they would
still probably wait to obtain more information before taking any form of shelter
or enact a safety plan. Most of the participants said it would be beneficial
to see the expected track information Warn-on-Forecast will provide to
help make their decisions on whether they felt the need to take safety
measures. The results in this study will help to aid the National Severe
Storms Laboratory in further development of the Warn-on-Forecast system
with respect to public perspectives on longer lead times and other information
needs.
Toward an Analysis of the Influence
of the Urban Heat Island Effect on Single-Cell Convective Cloud Trajectories [PDF]
Joshua Turner
Mentors: Brian Vant-Hull (CUNY)
*Exchange with CUNY's REU
This is an initial analysis of how the Urban Heat Island (UHI) Effect influences
convective cloud trajectories. Case studies have been done in the past that
demonstrate the observed movement of convective storms around various urban
areas like Atlanta and New York City. This analysis uses the GOES-East satellite
to track single-cell convective cloud towers (SCCTs) and the algorithm for
following the SCCT tracks them using infrared data from satellite observations
taken at 15-minute intervals. Matlab was then used to filter and extract
suitable trajectories by using thresholds on both speed and direction. Following
the filters to determine viable trajectories, another process was developed
to determine where along the trajectory there existed a significant deviation
in the propagation of the particular SCCT. After these specific perturbations
in trajectory angle were found, they were then cross-referenced with locations
of urban areas in the domain using a density plot to determine where the
highest concentration of significant perturbation points occurred.
Comparisons of Flood Affected Area
Derived From MODIS and Landsat Imagery [PDF]
Kevin Van Leer
Mentor: John Galantowicz (AER, Inc.)
During the first few weeks of June 2008, the Midwest experienced a weather
system that dropped large amounts of rain across the region. In southern
Indiana the Wabash and White Rivers went several feet above their flood
stage and many people were displaced from their homes and businesses.
This study uses the event as a test case for comparisons of resolutions and
data from the MODIS and Landsat 5 TM sensors. A k-means classification
scheme is created to cluster the data to identify the flood region in
the imagery. Calculations are then made to estimate a flood area for each
resolution. A statistical study is then performed to analyze false positive
and and false negative rates using Landsat imagery as "ground
truth." The results of the area estimate and
statistical study support a claim that coarse resolutions, 1 and 2 kilometers,
provide the most
accurate measuring of area in large scale flood events, but the overall location
of the fine details of the flood are lost. The finer resolutions (500
and 250 meters), while more accurate about locations of fine details,
have a higher false positive and false negative rates that raise questions
about their ability to effectively use this classification scheme to measure
overall area. The conclusions of this research promote further questions as to what resolutions could be effectively
used gain anaccurate map and measurement of the innundated area's
extent.
Measured Severe Convective Wind Gust Climatology of Thunderstorms
for the Contiguous United States, 2003-2009 [PDF]
Andrew Winters
Mentors: Bryan Smith and Corey Mead (NOAA NWS SPC)
A severe convective wind gust climatology spanning 2003-2009 for the
contiguous United States is developed using measured Automated Surface
Observing System (ASOS), Automated Weather Observing System (AWOS), and
Oklahoma Mesonet wind observations. National Lightning Detection Network
and Radar Mosaic/Level II data are used amongst other quality control
checks to identify and remove erroneous observational data. The filtered
observations are then time matched with a number of diagnostic mesoanalysis
fields from the Storm Prediction Center (SPC) for assessment of the severe
convective wind gust environments. These data are then binned based on
season and geographic region in order to identify atmospheric regimes
characteristic to different parts of the country. The filtered observations
are compared to storm reports archived by the SPC. Finally, a relatively
denser surface observing network in Oklahoma is utilized to determine
how consistently severe convective wind gusts are recorded by differing
networks (i.e. ASOS/AWOS and Oklahoma Mesonet).
This study characterizes and contextualizes observations associated
with southeast weak shear environments and contiguous U.S. strong
deep layer shear, higher CAPE atmospheric regimes. Additionally,
results exemplify the usefulness and necessity of a dense observing
system network and demonstrate that the highest frequency of measured
wind gusts occur throughout the southern and central High Plains
and in a corridor from South Dakota across the southern Great Lakes
region.
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