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Dual-Polarization Operations Assessment

Dual-Polarization Operations Assessment. Status Update on Development Process Progress on RDA work Progress on RPG work Where we are with Beta and Deployment. RDA Work. Data Quality Team Many, many, many problems identified, researched and fixed

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Dual-Polarization Operations Assessment

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  1. Dual-Polarization Operations Assessment Status Update on Development Process Progress on RDA work Progress on RPG work Where we are with Beta and Deployment

  2. RDA Work • Data Quality Team • Many, many, many problems identified, researched and fixed • Training, engineering and research experts who meet regularly • Beta test will be key… • Currently Scheduled for Dec 2010 – March 2011

  3. What Dual-Pol Does Not Change • Basic WSR-88D characteristics • Frequency, beamwidth, data resolution • VCP sampling • Elevations, update time, number of pulses per radial • All Pre-Dual-Pol products and algorithms You control how and when you integrate Dual-Pol information into your methodology

  4. Dual-Pol and CMD • CMD will not be operational with initial deployment • Manual clutter management returns! • Bypass Maps for normal clutter • All Bins for AP clutter • CMD will return with the first full build after Dual-Pol • Build 13…scheduled Jan/Feb 2012 • Development work underway…

  5. Dual-Pol and Sensitivity • Sensitivity: ability to detect weak returns • Measured as ___ dBZ @ ___ range for returned signal = noise • Affected by transmitted power and system noise • If returned signal is above the noise, life is good!

  6. Dual-Pol Sensitivity Loss • Dual-Pol radars transmit and receive both horizontally (H) and vertically (V) • For same range, same target, WSR-88D Dual-Pol has less returned power than before

  7. Dual-Pol and Sensitivity • Dual-Pol sensitivity loss means more gates that are “Off” than before • Returned signal not processed into base data Detectable Not Detectable

  8. Dual-Pol Sensitivity Loss • A bit more loss from hardware that does the splitting • Cabling, built-in test equipment, etc. • Per site expected sensitivity loss due to Dual-Pol conversion 3.5 – 4 dB • Impact on operations?!!?

  9. Dual-Pol Sensitivity LossImpact on Operations? • SME panel assembled to evaluate impact of 4 dB loss • ROC engineering, NWS SSDs, NSSL, and WDTB • Spectrum of weather events evaluated • 4 dB loss simulated (Don’t try this at home)

  10. Dual-Pol Sensitivity LossImpact on Operations • Events evaluated • Dryline – KS (KDDC) • Freezing drizzle – KS (KICT) • Marginal lake effect snow – NY (KBUF) • Tornadicsupercell along boundary – CO (KFTG) • Outflow boundaries from convection – OK (KTLX) • Short range smoke plumes – OK (KTLX) • Multiple outflow boundaries/popcorn showers – FL (KEVX) • California wildfires – CA (KSOX) • Hurricane Ike landfall – TX (KHGX) • Nor’easter snowstorm (snowmaggedon) – VA (KLWX) • Go Paul!!

  11. Now For Calibration of Z • Calibration is about the magnitude of Z values KOUN 0.5˚ KCRI 0.5˚

  12. Calibration of Z • Given appropriate Z calibration and same scatterers in a volume • 40 dBZ is 40 dBZ, 30 dBZ is 30 dBZ, etc. • Assuming Rayleigh scattering… • Work is ongoing • Z calibration • ZDR calibration

  13. Sensitivity and CalibrationSummary • Sensitivity: more Off gates with Dual-Pol • Per site expected sensitivity loss due to Dual-Pol conversion 3.5 – 4 dB • Less return from very weak signal areas • Z Calibration: magnitude that is assigned • Dual Pol calibration much more complex • Be kind to your techs! • 8 hour check no longer transparent

  14. Now For Attenuation • Impact on base moments does not change • Impact on Dual-Pol products is more significant KOUN: Dual-Pol KCRI: Single Pol

  15. Attenuation and Dual Pol Products • What has happened to ZDR? • What are the consequences?

  16. Attenuation and Dual Pol Products • What has happened to CC? • What are the consequences?

  17. RPG Work • Dual-Pol algorithms: lots of room to grow* • Knowledge base (research) central Oklahoma • Base data from RDA only recently mature enough for RPG testing • Greatest emphasis now is QPE MLDA HCA *Been there, done that: WSR-88D original development

  18. Quantitative Precipitation Estimation Algorithm • Benefits of Dual-Pol applied to rainfall estimation • Dual-Pol better at identifying ground clutter, biological scatterers, large hail, etc. • Prevent these returns from being converted to rainfall • Legacy Precipitation Processing System and products do not go away

  19. QPE Basics • QPE is an RPG algorithm • QPE & PPS have similarities & differences • QPE supported by other Dual-Pol algorithms • Hydrometeor Classification Algorithm (HCA) • Melting Layer Detection Algorithm (MLDA)

  20. QPE Similarities With Legacy PPS • Accumulations start and stop based on coverage and intensity • Actual start and stop times will differ

  21. QPE Similarities With Legacy PPS • Exclusion zones • Prevent returns (e.g. moving clutter) from being converted to rainfall • Zones defined separately for PPS and QPE • Recommend same zones initially

  22. QPE Similarities With Legacy PPS • Storm total accumulations reset at RPG

  23. QPE Similarities With Legacy PPS • Concept of Hybrid Scan same • Find lowest unblocked elevation of valid precipitable return • Common accumulation periods for PPS and QPE products • One hour, storm total, user defined

  24. QPE Differences From Legacy PPS • HCA and MLDA input used to build QPE Hybrid Scan • Prevent non-meteorological returns (e.g. clutter, biological) from conversion to rain rate • Determine best rain rate computation to use

  25. How QPE Builds Hybrid Scan Ice Crystals • Each bin gets Hydroclass value from HCA Clutter Graupel Unknown Big Drops Biological Heavy Rain Hail-Rain Dry Snow Rain Wet Snow

  26. How QPE Builds Hybrid Scan • GC (clutter), UK (unkown) • Go up next tilt • BI (biological), no echoes • Don’t search higher and set rain rate to 0.0 • Remaining Hydroclass values are precipitable • Lots of details on this one…some other time!

  27. QPE Differences From Legacy PPS • QPE rain rate product every volume scan Hybrid Scan Reflectivity PPS R(Z) R(Z) Hybrid Scan Hydroclass QPE R(Z,ZDR) R(KDP)

  28. Why is QPE Work Going On NOW? • Base data from RDA only recently (May!) mature enough for RPG testing • But wait! There’s more! LNAs switched out in July • RDA work requires frequent shutdowns • QPE and PPS both require • High quality base data • Appropriate clutter filtering • RDA stable and calibrated

  29. QPE is an Algorithm • Base Data Rules!

  30. QPE Work Currently Underway • Attenuation and QPE • Easy to identify in base data

  31. QPE Work Currently Underway • QPE can show zero rain rates • Attenuation correction for DP variables being worked

  32. QPE Work Currently Underway • R(KDP) performance looks good so far • R(Z,ZDR) performance • Significant underestimation of high efficiency (warm rain) rainfall • Underestimation similar to R(Z) R(Z) Hybrid Scan Hydroclass QPE R(Z,ZDR) R(KDP)

  33. QPE Work Currently Underway • R(Z,ZDR) performance • Warm rain event, flash flooding in OKC • We were lucky to discover this (warm rain in OK and KOUN was running) Gage: 10.21 QPE: 4.40 PPS: 4.81

  34. QPE Work Currently Underway • Current version of R(Z,ZDR) based on large group of central OK rain events • “Individual cases may vary” • Solution requirement: no operator parameter changes

  35. Thank You • You are an important part of this process

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