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Status, performance, and upcoming needs relating to the GPS dropsonde for operations and research

Status, performance, and upcoming needs relating to the GPS dropsonde for operations and research. Michael Black Hurricane Research Division OAR/AOML Jeffrey Smith NMAO/AOC.

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Status, performance, and upcoming needs relating to the GPS dropsonde for operations and research

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  1. Status, performance, and upcoming needs relating to the GPS dropsonde for operations and research • Michael Black Hurricane Research Division OAR/AOML • Jeffrey Smith NMAO/AOC

  2. A brief history of the NCAR GPS Dropsonde • Developed by NCAR for NOAA, DLR, and NCAR in 1996 • First used for research in FASTEX in 1997 • Became operational for hurricane reconnaissance and surveillance in 1997- AFRES C-130, NOAA P3 & G-IV • Sole instrument for highly successful NOAA surveillance missions • Used worldwide in research projects • Primary tool for operational surface wind measurements in hurricanes 1998-present

  3. Current GPS (GPS-121 Rev. D) Dropsonde: • Manufactured by Vaisala, Inc. in Colorado under license through UCAR • Three major revisions since 1997 plus several additional design and manufacturing changes • Measures P, T, H and computes wind at 2 Hz • GPS 121 “codeless” receiver - winds computed within aircraft AVAPS system • High failure rate (>50%) of low-level (10-500 m) wind in strong winds (>50 m/s) • Subject to RF interference near coast from research radars-resulting in total wind failure

  4. Low-level wind failures 360 m 110 m 45 m

  5. Necessity for a replacement GPS receiver: • GPS 121 “codeless” receiver no longer manufactured by subcontractor • Vaisala has found no equivalent replacement receiver • Performance of Vaisala 1- Hz prototype unsatisfactory • GPS 121 will be unreliable beginning in 2006 because of interference from Galileo satellites-possibly faulty or no winds

  6. NCAR EOL (formerly ATD) Division has produced a prototype sonde with an OEM (UBLOX) GPS module capable of 4 Hz winds • First 6 tested from G-IV in 2004 NWS Winter Storms Project - results encouraging but some problems • Hardware and software modifications made prior to 2004 hurricane season • 30 additional UBLOX sondes (6 G-IV, 24 P3) tested during the season

  7. GPS121 UBLOX 59 m/s, 962 mb 50 m/s, 980 mb Comparison of GPS-121 and UBLOX winds in Frances

  8. GPS121 59 m/s, 938 mb UBLOX 39 m/s, 942 mb UBLOX Captures Critical Lower Boundary-layer Structure

  9. Comparison of sample GPS 121 and UBLOX Raw data values GPS121 UBLOX

  10. Typical GPS 121 wind performanceSample of 2004 processed sondes

  11. Typical UBLOX wind performanceSample of 2004 processed sondes

  12. Comparison of sample GPS 121 and UBLOX winds in lowest 100 meters GPS121 UBLOX

  13. Advantages of the UBLOX Dropsonde • Compatible with current aircraft systems • Retains 2 Hz wind resolution with potential for 4 Hz • Can verify winds before launch • Provides independent measurement of altitude • No interference fro coastal radars • Fast acquisition of winds • Better lock on GPS satellites - less wind dropouts • High reliability • Quality OEM GPS receiver • Very few low-level wind failures - even in high winds

  14. IMMEDIATE NEEDS Must use existing stock of GPS 121 sondes! Prioritize allocation, usage of 121 & UBLOX sondes AFRES and NOAA TC reconnaissance missions: • UBLOX in Cat. 3 or higher eyewall • GPS 121 sondes elsewhere and for training? • GPS 121 sondes for G-IV surveillance missions NOAA, ONR, and NASA research missions • Equitable allotment of UBLOX sondes for projects: HRD IFEX, NESDIS Ocean Winds,ONR-NSF RAINEX, NASA TSCP 2) Use UBLOX for high wind regimes or where BL structure is critical

  15. CURRENT & LONG-TERM NEEDS PROVIDE FUNDING SUPPORT FOR MODIFICATION & DEVELOPMENT OF GPS SONDE Current needs: • Continued testing & modification of UBLOX sondes • Engineering design of new or modified battery- necessary because of hazardous materials regulations • Engineering efforts to reduce other hazardous materials • Design and integrate discontinued components including those in telemetry chassis and PTU module Longer-term needs: • Telemetry design enhancement- will allow for improved performance and 4 Hz wind data • Design of a simpler and less expensive MWG module • Engineering to implement pre-loading of position data for immediate acquisition of winds after launch

  16. Suggested actions • IHC working group discuss and agree on a plan to utilize the existing GPS 121 and new UBLOX sondes for involved agencies • The dropsondes need to be redesigned every 5-7 years to keep up with technology and regulatory changes: A committee be formed to coordinate sonde development efforts and funding sources

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