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Fiber-optic Temperature Profiler for Long Duration Balloon Missions

High resolution temperature measurements of the Tropical Tropopause Layer using a laser-based sensor suspended below the balloon.

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Fiber-optic Temperature Profiler for Long Duration Balloon Missions

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  1. Fiber-optic Temperature Profiler for Long Duration Balloon Missions High Resolution Temperature Measurements of the Tropical Tropopause Layer Planetary Science • Space Physics • Solar Influences • Atmospheric Science • Engineering • Mission Operations & Data Systems http://lasp.colorado.edu Lars Kalnajs – LASP /University of Colorado Sean Davis – NOAA ESRL Chemical Sciences Division

  2. Concept High resolution temperature profile measurements covering ~4km below balloon (from ~13 – 17km) Measurement region spans the Tropical Tropopause Layer Laser based sensor to measure the temperature along ~4km of fiber suspended below balloon Profile temperature at rates up to 1/min for the entire duration of the flight Vertical resolution of 2m and temperature precision better than 1C Photo: Sean Davis Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  3. Instrument Overview Measures the temperature of a standard multi-mode communications fiber. Based on the intensity of the Stokes and Anti-Stokes Raman scattering spectrum. Ratio of Stokes (+10nm) to anti-stokes (-10nm) gives temperature, time of flight gives position. FPGA based sampling at very high rates (107 samples s-1), coherent averaging (105 points) gives high precision End-of-Fiber unit determines position, pressure and temperature at bottom end of fiber. Spectra from www.raman.de Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  4. Prototype Instrument Motor/Gear Box Optical Bench Fiber Reel GPS + Data Acquisition Motion Controller Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  5. Optical Fiber 50/125 μm Multimode Optical Fiber 240 μm polyamide coating Human Hair 125 μm glass cladding 50 μm glass core 150 grams / kilometer <2Kg Practical Breaking Strain High Albedo Coating 600 μm Liquid Crystal Polymer Coating 50/125 μm Optical Fiber 400 grams / kilometer >20 Kg Breaking Strain Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  6. Instrument Performance 1-σ temperature accuracy: 1°C Spatial resolution: 2m (1/e change) Scan speed: 100 meters / second Raw Data rate : 5 bytes/meter/scan Power: 10W continuous, 4W 10 profiles/hour Weight: 7 Kg (prototype) 4 Kg (expected flight model) Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  7. Tower Tests Image: Sean Davis Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  8. Flight Tests Click to add image credit info Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  9. Flight Tests Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  10. Further Work Re-print fiber reel to allow 2km of 600 μm LCP fiber Quantify daytime radiative bias on measured temperature. Test fiber coatings to minimize and correct for radiative bias. Establish wavelength division multiplexing for communication from EOF -> Gondola @ 1550nm Build low power End of Fiber unit with GPS, pressure sensor, and precision thermistor Test self deploying fiber spool Further test flights this summer! Image: linden photonics Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  11. Science Questions for Stratéole 2 Provide a precise, high frequency measurements of the thermal structure of the Tropical Tropopause Layer Greatly increase the density of high resolution measurements over current radiosonde based data Investigate the location and temperature evolution of the cold point tropopause Obtain unprecedented detail of gravity wave propagation through the TTL on scales unresolved by satellite sounders High frequency profiles will provide direct measurement of gravity wave phase speed spectrum Validate and improve atmospheric wave parameterizations in GCMs Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  12. Acknowledgements This work has been supported by an NSF EAGER award #1419932 and a CU/CIRES Research and Development Grant. Thanks to: • Sean Davis (NOAA ESRL) • Terry Deshler (U. Wyoming) • Joan Alexander (NWRA) • Greg Wright (LASP) • Edge of Space Science Click to add image credit info Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

  13. QUESTIONS? Fiber Temperature Profiler - Strateole Workshop; Lars Kalnajs

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