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2 Purdue Undergraduate Research Conference
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Conclusions:
• We developed a prototype high wind alert
system based on 22 days of XTRRA
velocity observations.
• Some additional challenges remain in
minimizing false alarms.
• Eventually, we hope to send automated text
alerts to interested parties when high winds
threaten campus.
Methodology:
High wind alerts for Purdue campus based on observations
from the X-band Teaching and Research Radar (XTRRA)
Author: Lauren Warner
Research Mentor: Prof. Robin Tanamachi, EAPS
Background:
• As a result of the 2011 Indiana State Fair
stage collapse incident, Purdue University
enacted a new wind restriction (13 m s
-1
)
for tents during outdoor events (M. Baldwin
2019, pers. comm.).
• Currently, winds are monitored by
volunteers using handheld weather meters.
• The recent installation of the X-band
Teaching and Research Radar (XTRRA) at
Purdue may allow these alerts to be
automated.
• Our objective in this study is to develop
a prototype automated high wind alert
system based on XTRRA observations.
Results:
• Our prototype system appears to work well,
with strong signals for real high wind
events. (Example below)
References:
Doviak, R. J., and D. S. Zrnić, 1993: Doppler Weather Radar and Observations. 2 ed. Academic Press, 562 pp.
Gourley, J. J., P. Tabary, and J. Parent du Chatelet, 2007: A fuzzy logic algorithm for the separation of precipitating from
nonprecipitating echoes using polarimetric radar observations. J. Atmos. Oceanic Technol., 24, 1439-1451,
doi:10.1175/JTECH2035.1.
Rinehart, R. E., 1997: Radar for Meteorologists. 5 ed. Rinehart Publications, 428 pp.
Witt Associates, 2012: An Independent Assessment of the August 13, 2011 Indiana State Fair Collapse Incident. 182 pp.
Available from https://www.wittobriens.com/wp-content/uploads/2017/09/171758_1883990_3448726_1_6041423_Witt-
Associates-Indiana-State-Fair-Report-April-2012.pdf.
Acknowledgements:
Prof. Michael Baldwin (EAPS) provided information
regarding the wind speed limits for outdoor events. The
College of Science provided the photograph of the XTRRA
being installed.
Example:
(a)
(b)
(c)
(d)
← The XTRRA
radar being
installed on top of
Wang Hall on 20
June 2018. Photo
courtesy of the
Purdue College of
Science.
Raw
Doppler
velocity
data
3-dB SNR
threshold,
texture
filter
Height
restriction,
median
filter
Statistical
outlier
removal
Velocity threshold
(13 m s
-1
)
High Wind
Alert
20
km
Parameter
Value
Center frequency
9.41 GHz
Half
-power beam width
1.0
°
Polarization scheme
Dual linear; STAR
Peak / average transmitted power
16 kW / 24 W
Maximum unambiguous range
50 km
Maximum unambiguous velocity (dual
-PRT)
30 m s
-1
Range resolution
50
m
Azimuthal range
0
- 360°
Elevation range
0
° - 180°
Antenna diameter
2.4 m
Antenna gain
45 dB
Live XTRRA images
(a) Reflectivity in dBZ and (b)
Doppler velocity in m s
-1
at
1330 UTC on 21 September
2018 at 1.3°. (c) Time series
of gates that exceeded the
velocity threshold.
Doppler velocity (m s
-1
)
Squall line passage
(a)
(c)
(b)
