CSU-CHILL Update S/X band development and recent operations Solid State transmitter project

1. CSU-CHILL UpdateS/X band development and recent operationsSolid State transmitter project

2. CSU-CHILL Radar Architecture Antenna Radome Radar Trailer Signal Processor Dual Transmitters Waveform Generator Storage Processor Mass Storage Network Sync Local Display, Control Remote Display, Control GUI with S-polKa Dual Receivers Digitizer, Filtering Antenna Servos Gateway Angle System Control Internet CSU-CHILL visit for ATS741

3. CSU-CHILL Antenna Main reflector Subreflector Feed horn • Dual-offset Gregorian antenna • Choice of three symmetric OMT feed horns • S-band only • X-band only • Dual wavelength, S/X • S-band beamwidth 1 degree • X-band beamwidth 0.3 degree • Two way sidelobe levels better than 50 dB at S-band; 70 dB at X-band • Single-wavelength feeds achieve exceptional cross-polar isolation better than 50 dB • Median LDR in light rain of -38 dB CSU-CHILL visit for ATS741

4. Dual frequency (S and X-Band) horn installed on 8.5m diameter dual-offset antenna X-Band 3 dB beam width ~0.3 deg; beam axis coincident with S-band

5. Development of X-band radar addition to CSU-CHILL X-Band hardware adopted from UPRM MRI radar (CSU ECE collaboration effort)

6. S/X-Band PPI data: Convergence patterns along eastern edge of convective echoes X-band delivers nearly same range sensitivity as S-band despite significantly lower power. Antenna gain is 54 db! Gain ~ Area/λ2 S-band X-band Higher resolution at X-band is readily evident X-band data not corrected for attenuation

7. Better differential propagation phase sensitivity at X-Band vs. S-Band Significant advantage for cold season precipitation and microphysics “Negative” phidp more evident at X-band, indicating vertically aligned ice crystals oriented by an electric field

8. FROST 2013 • carried out by CSU (Rutledge, Kennedy) and NCAR/RAL (Kumjian, Rasmussen, Metro State students); 20 hour project • CHILL X-band; NCAR X-band plus assortment of surface measurements at NCAR Marshall Field site • soundings • documented many winter storms, many overnight (autonomous) operations conducted • CHILL X-band polarimetric observations at high resolution

10. HEAVY AGGREGATE SNOWFALL CAUSED MAJOR TRAFFIC ACCIDENT ON I-25

12. 15 April 2013 1709 UTC 145 degree RHI Impressive convective scale generating cells

14. Aggregates Fallstreak Pristine crystals

15. Zdr Z Wednesday 11:52 MDT More examples • f rhohv

16. Solid-state S-band Transmitter upgrade for CSU-CHILL ASR-11 solid state transmitter donated to CSU by Raytheon

17. High level goals • At the NSF radar workshop, strategic benefits of solid-state class radar transmitters were discussed and emphasized for modern weather radars, both from advanced measurement perspective as well as long term measurements, and robust remote operations for climate observations. • CSU-CHILL is a very advanced weather radar ,with aligned dual-frequency dual-polarization antenna, and state of the art signal processor. The transmitter is the only component that is “classic”, and was the limiting factor in advancement. • Air surveillance radars (ASR) operate in the lower S-band, same as weather radar and they have access to solid state transmitters. • Demonstrate that the ASR class transmitter can be used effectively for dual-polarization implementation for weather radars. • This upgrade will keep CSU-CHILL radar at the forefront of research weather radars • This is being developed as a common platform that can be deployed with other S-band radars such as N-Pol and S-polKa

18. Solid-state transmitter plan S-polKa Solid-state Transmitter Common Signal Processor Waveguide Switch Klystron Transmitter Radar Users

19. Advantages of Solid-state transmitter • From a facility perspective, the first and foremost is the ability to have state of the art, robust transmitter for weather radar, with enhanced, fully remote operation for field deployments • Range-Velocity Ambiguity Mitigation, through the use of frequency diversity and coding diversity offer improved performance over current techniques • Data Quality Improvement, specifically, reduced variance in estimated parameters, due to range-averaging of the additional independent samples introduced by both Frequency Diversity and Pulse Compression. • Faster Scanning of a volume, without sacrificing data quality, due to range-averaging of the additional independent samples introduced by both FrequencyDiversity as well as Pulse Compression

20. Timeline of major events • Major events and milestones on the development timeline are shown • Each subsystem is considered complete after it has been bench-tested ASR-11 transmitter

21. CSU-CHILL projects • Major support for DC3 in summer 2012; NSF REU 2012 • Winter 2013, FROST (20 hour in collaboration with NCAR • Three spring 2013 VCHILL remote tours/instruction; SUNY Oswego, North Carolina State and Iowa State • Summer 2013 projects include NSF REU and Unmanned Aircraft System Sensor Calibration (U. of Nebraska), several 20 hour projects • Summer 2014, FRONT-PORCH (proposed)

22. AMS Short Course on Weather Radar Calibration Laboratory: 14 Sept 2013, CSU-CHILL Site , CO • The goal of the course is to provide not just the theory, but practical demonstrations calibration methods, so that the practitioners understand the intricacies of good calibration. The course is aimed at students and scientists who desire to know the details of radar calibration from a practitioner’s view point. • The course will be divided into two parts. The first will describe briefly the fundamental physical principles of calibrating radar and the special aspects of calibrating weather radar.  This segment will also introduce the recent advances such as calibration of dual-polarization radar.  The second part will demonstrate the practical procedures, and with emphasis on laboratory style work. • The organizer and chief instructor of this course is Prof  V. Chandrasekar, Colorado State University. He will be joined by leading experts in the field, namely, Prof Paul Smith (Professor Emeritus SDSM&T), DrNitinBharadwaj ( PNNL ) and Dr Luca Baldini ( ISAC).