ECPI University capstone project to present ideas about replacing existing WSR-88D weather radar systems with new phased array radars.

1. DAVID KANE
CAP480
16 OCT 2016
Images: Skow, 2013; & Weather Radome, n.d.

2. • Weather radar is used by meteorologists worldwide to identify weather
patterns
• Radar typically shows “returns” in varying intensities
• Larger and more dense rain, snow, and ice show up with greater intensity
• Strong returns are typically associated with heavy rain or hail, but can also show birds and
insects
• Current weather radar utilizes a rotating and elevating dish inside a radome
• The dish looks like a satellite dish, but is pointed toward the horizon
• The radome protects the dish from the elements
• Maintenance is required for the klystron emitter, motors, brushes, bearings, etc.
• The klystron emitter is radioactive, leading to potential environmental issues
2 Images: Skow, 2013; & Weather Radome, n.d.

3. •The rotating and elevating dishes require a lot of time to “sweep” 360° around
• This is the line that sweeps across your area when the local weather reports are shown on TV
• Replacing these mechanical radars with solid state radars has many advantages,
namely:
• No mechanical parts to fail or require expensive maintenance
• Quicker “scan” of all returns within range
• Dynamic and simultaneous multiple beams that are electronically steered
• Faster identification and real-time tracking of severe weather signatures
• This will result in warnings being issued sooner, giving the public more time to react and prepare
• If the current ground based mechanical weather radar dishes are replaced by
solid state phased array radar systems, severe weather can be identified sooner,
giving the operators the ability to issue warnings earlier and saving lives.
3 Images: Skow, 2013; & Weather Radome, n.d.

4. • WWII aircraft radar operators noticed irregularities on displays
• Later realized clutter was caused by weather in the vicinity (Moran, 2016)
• Decommissioned military radars
• Retuned for weather detection
• Began deployment across the country in 1947
• Only detected signals and had B&W displays (Moran, 2016)
• Electronics revolutionized radar in the 1970s with color displays (Moran, 2016)
• NEXRAD Doppler technology introduced in the late 1980s
• Detection of individual motions within the storms now possible (Moran, 2016)
Images: WWII Radar Operator, Radio News, 1945; WSR-57, 1974 Super Outbreak, n.d.; WSR-74, Marquette Station History, n.d.; Benton County Supercell, 2010; & GRLevel3, n.d.4

5. • Upgrades in the 1990s led to real time radar data being provided online to any
interested user
• Technology upgrades led to dual polarization in the 2010s
• Could discriminate between different types of precipitation and non-weather phenomenon
such as birds (WSR-88D Dual Polarization Background and Status, n.d.)
• No major hardware upgrades in 30 years
• Current system has been used for nearly as long as weather radar existed in total when it was
first installed
• Weather Radar network is in serious need of modernizing
• Exponential increases in computer processing power since the 1980s could result in higher
quality streams of data, giving even more detail to storm signatures
Images: WWII Radar Operator, Radio News, 1945; WSR-57, 1974 Super Outbreak, n.d.; WSR-74, Marquette Station History, n.d.; Benton County Supercell, 2010; & GRLevel3, n.d.5

6. • Radar is short for Radio Detection and Ranging (Skow, 2013)
• Radar transmitter sends out a short pulse from rotating dish (Skow, 2013)
• Radar signal propagates through air at the speed of light
• Signal bounces off object, which can be cloud droplet, rain, hail, dust, terrain, birds, bugs, etc.
• Signal is scattered in all directions by Mie or Rayleigh processes
• Part of original signal is reflected back to dish, also at speed of light
• Energy of returned signal analyzed to determine size, shape, state, and concentration (Skow,
2013)
• Radar “beam” is like a cone extending from dish, widening by 1000 feet every
10 miles
• Beam is affected by atmosphere and limitations that were compromises of available
technology (Skow, 2013)
Image: Wolff, n.d.6

7. • Dish takes a minimum of 4m30s to rotate through 14 elevations (Skow, 2013)
• Tornados typically last around 10 minutes (Edwards, 2016)
• Simple math reveals dilemma: radar refresh rate is inversely proportional to
warning lead time
• The longer it takes the radar operator to see potential severe weather, the longer it takes to
warn the public
• If the radar information could refresh faster, radar operators could see severe indicators
quicker
• Solution sounds like we could just speed up the dish rotation, but it’s not that easy
• “Doppler Dilemma” is when the pulses sent out return in the wrong listening window
• “Range Folding” makes signals appear closer, giving false readouts on displays (Haby , n.d.)
Image: Wolff, n.d.7

8. • No moving parts
• Saves on maintenance costs in the very least
• “Beam” is generated using computers and electronic radar emitters, doing away
with single mode VCPs
• Beam can be focused and steered at near light speed (AN/APG-79, n.d.)
• Simultaneous beams can detect and stay on target (AN/APG-82(V)1, n.d.)
• Improves range due to existing radar needing to sweep away from targets
• Radar operator can focus in on an area of interest and monitor continuously while radar continues “sweeping”
• Very little signal leakage (Defense Industry Daily, 2007)
• Improves “ground clutter” that is unavoidable with existing radar and must be removed in post processing
• Also helps reduce interference
Images: Research Tools: Multifunction Phased Array Radar (MPAR), n.d.; & MPAR (Multifunction Phased Array Radar), 2009.8

9. • Can scan sky in less than 1 minute (MPAR, n.d.)
• Compare to 4m30s for current radar
• Quicker identification of storm signatures means citizens warned sooner about severe
weather threats
• Bonus: Can also replace current FAA aircraft radars (MPAR, n.d.)
• Simultaneous weather and aircraft interrogation
• Cost savings by eliminating unnecessary redundancy
• Double Bonus: Can also form communications link between ground and aircraft
(Defense Industry Daily, 2007)
• Has the potential for future ground-to-aircraft high speed data links
• At the very least, latest weather graphics and airport information can be streamed
Images: Research Tools: Multifunction Phased Array Radar (MPAR), n.d.; & MPAR (Multifunction Phased Array Radar), 2009.9

10. • Limited research has been done
• MIT has built a prototype from scratch (Herd, 2011)
• University of Oklahoma (Multifunction Phased Array Radar, n.d.)
• NWS has an operational MPAR (Multifunction Phased Array Radar) in Oklahoma
• Uses four 1970s US Navy decommissioned Aegis AN/SPY-1 ship radars reconfigured for
weather duty
• The four faces overlap on the edges, providing 360 degree coverage
• Testing alongside existing radar has proven it works
• Full updates come as fast as 30 seconds while existing radar takes 4m30s
• Annual software upgrades ensure cutting edge features are continuously developed
• University of Oklahoma researching curved radar techniques
• Potential to revolutionize radar by eliminating dead and overlapping coverage areas
(University of Oklahoma Advanced Radar Research Center, n.d.)
10 Images: O’Donnell, 2010

11. • An “independent study” estimates $4.5B will be saved over the lifecycle compared to
existing radar systems
• This figure takes replacement of both existing NWS/DoD weather and FAA aircraft radar systems into account
(Multifunction Phased Array Radar, n.d.)
• The most important thing: Tornado warnings consistently issued 20 minutes in advanced
• Compared to 13 minutes with existing radar
• False alarm rates also reduced by 75% (Multifunction Phased Array Radar, n.d.)
• Military aircraft phased array radars are being continuously upgraded
• More recent decommissioned radar systems could be utilized to bring in additional
capabilities
• Cost effective to reuse old military radar that has already been paid for
• Prototype 10 panel small scale system built in 2015 for research purposes (Multifunction
Phased Array Radar, n.d.)
11 Images: O’Donnell, 2010

12. Type Model Number Max Range Update Frequency
Weather WSR-88D 156 230-460km 4-6 minutes
Weather TWDR 45 90-460km 1-5 minutes
Aircraft ARSR 101 370-460km 12 seconds
Aircraft ASR 233 110km 5 seconds
Type Model Number Max Range Update Frequency
Weather and
Aircraft
MPAR Approx. 150 300-460km 0 seconds (interrogate)
12 seconds (aircraft)
30 seconds (weather)
National Research Council, 2008
National Research Council, 2008
12 Images: Antennas For Communications, n.d.; & Research Tools: Multifunction Phased Array Radar (MPAR), n.d.;

13. • Radar is an indispensable tool for weather forecasters when interrogating severe weather
• Current Weather Radar is very “long in the tooth” at nearly 30 years in place
• Previous major overhauls took places every 10-20 years
• Phased Array Radars are the next logical step in weather radar technology
• Limited research and funding has been provided
• US Navy provided four 35 year old decommissioned Aegis radar panels
• Much newer technology is available to cutting edge military aircraft
• Why not harness this to protect lives at home?
• More funding and newer equipment needed to properly study effectiveness
• Why? Phased Array Radars provide a 65% increase in tornado warning lead times
• The longer people have to prepare and move to shelter, the more lives will be saved
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14. 1974 Super Outbreak: Observations. (n.d.). NWS [image]. Retrieved from
https://www.weather.gov/iln/19740403_obs
AN/APG-79 AESA Radar Active Electronically Scanned Array. (n.d.). Raytheon. Retrieved from
http://www.raytheon.com/capabilities/products/apg79aesa/
AN/APG-82(V)1 AESA Radar. (n.d.). Raytheon. Retrieved from
http://www.raytheon.com/capabilities/products/apg82v1/
Antennas for Communications. (n.d.). HIT Radome & Dish [image]. Retrieved from
http://www.radome.net/jpg/HIT_radome&dish1.jpg
Benton County Supercell of June 14 2010. (2010). NWS [image]. Retrieved from
http://www.weather.gov/lot/2010jun14
University of Oklahoma Advanced Radar Research Center. (n.d.). Cylindrical Polarmetric Phased Array Radar. Retrieved from
https://arrc.ou.edu/radar_cppar.html
Defense Industry Daily. (2007). Elec Tricks: Turning AESA Radars Into Broadband Comlinks. Retrieved from
http://www.defenseindustrydaily.com/elec-tricks-turning-aesa-radars-into-broadband-comlinks-01629/
Edwards, R. (2016). Tornado FAQ. Retrieved from
http://www.spc.noaa.gov/faq/tornado/
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15. Haby, J. (n.d.). Range Folding and the Doppler Dilemma. Retrieved from
http://www.theweatherprediction.com/habyhints/231/
Herd, J. (2011). Multifunction Phased Array Radar Panel. Retrieved from
https://www.ll.mit.edu/publications/technotes/TechNote_MPARpanel.pdf
Moran, D. (2016). A Brief History of Weather Radar. Retrieved from
http://blog.wdtinc.com/a-brief-history-of-weather-radar
MPAR (Multifunction Phased Array Radar). (2009). NWS [video; image]. Retrieved from
https://www.youtube.com/watch?v=6C2bKQlvRls
Multifunction Phased Array Radar. (2015). NWS. Retrieved from
http://www.nssl.noaa.gov/news/factsheets/MPAR_2015.March.16.pdf
National Research Council. (2008). Evaluation of the Multifunction Phased Array Radar Planning Process. National
Academies Press: Washington, D.C.
National Weather Service Marquette Station History Page. (n.d.). NWS [image]. Retrieved from
https://www.weather.gov/mqt/stationhistory
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16. O’Donnell, R. (2010). Airborne Pulse Doppler Radar [image]. Retrieved from
http://ece.wpi.edu/radarcourse/Radar 2010 PDFs/Radar 2009 A_14 Airborne Pulse Doppler Radar.pdf
Radio News. (1945). Radar: The Silent Weapon of World War 2 [image]. Retrieved from
http://www.rfcafe.com/references/radio-news/radar-silent-weapon-wwii-october-1945-radio-news.htm
Research Tools: Multi-Function Phased Array Radar. (n.d.). NWS. Retrieved from
http://www.nssl.noaa.gov/tools/radar/mpar/
Skow, K. (2013). NWS WSR-88D Radar Fundamentals. Retrieved from
http://www.meteor.iastate.edu/classes/mt432/lectures/ISURadarTalk_NWS_2013.pdf
Weather Radome. (n.d.). NWS [image]. Retrieved from
https://www.roc.noaa.gov/wsr88d/images/billings3.jpg
Wolff, C. (n.d.). Basic Principle of Operation [image]. Retrieved from
http://www.radartutorial.eu/15.weather/wx04.en.html
WSR-88D Dual Polarization Background and Status. (n.d.). NWS. Retrieved from
http://www.roc.noaa.gov/wsr88d/dualpol/DualPolOverview.aspx
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