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NOAA Water: Instrument and Data

NOAA Water: Instrument and Data. Troy Thornberry, Drew Rollins Ru-Shan Gao, Laurel Watts, Steve Ciciora , Rich McLaughlin, David Fahey NOAA ESRL CSD and CIRES, University of Colorado ATTREX Science Team Meeting 24 October 2013. The visible NOAA Water.

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NOAA Water: Instrument and Data

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  1. NOAA Water:Instrument and Data Troy Thornberry, Drew Rollins Ru-Shan Gao, Laurel Watts, Steve Ciciora, Rich McLaughlin, David Fahey NOAA ESRL CSD and CIRES, University of Colorado ATTREX Science Team Meeting 24 October 2013

  2. The visible NOAA Water • Main Enclosure: 48 cm x 43 cm x 35 cm, designed for Zone 12 • Total Instrument weight (incl. inlet and pumps): 40 kg

  3. Sample and calibration flow schematic

  4. Optical absorption cell • 39 cm physical path, 78 cm optical path • 2.694 µm DFB diode laser • WMS spectroscopy with 2f detection • Cell held at constant P, T, and flow • 0.6 s sample residence time at 600 sccm P

  5. TDL scan • Scan approximately 1 cm-1 at 10 Hz, co-average spectra to 1 Hz • Two H2O lines with a factor of ~20 difference in line strength • One or two CO2 lines

  6. Inlet pylon • Inlet pylon extends 27 cm from fuselage into the free stream • WV inlet rejects particles • TW inlet samples subisokinetically • Enhanced sampling efficiency for large particles • Sharp 90° and heated to 180°C to evaporate particles 27 cm

  7. WV inlet particle rejection • Inlet perpendicular to flow stream to prevent sampling of cloud particles • Design used successfully in the past with CIMS H2O and SP2 (MACPEX), CIMS HNO3 • Curve based on empirical study reported by Brixey et al., 2004 – application requires extrapolation from low U/U0

  8. TW inlet enhancement factor • Function of airspeed, pressure, temperature, volumetric sample flow, particle density • In TTL, typical values: • U = 4.47 m/s, U0 = 180 m/s • Based on CFD models from Krämer and Afchine, 2004 and Eddy et al., 2006

  9. Calibration vs MBW • Primary calibration by comparison with MBW 373LX reference cryogenic mirror hygrometer on the ground • Performed before, during and after ATTREX 2 deployment • MBW CMH instrument compared with PTB reference during AquaVIT2

  10. In-flight calibration • In-flight calibration used to assess stability of sensitivity • Range of mixing ratios generated by H2 oxidation on Pt catalyst • Only WV channel calibrated

  11. TW vs WV channel comparison • Good agreement between the two channels • TW = 1.04 * WV – 0.08 • Some residual clouds clearly not removed

  12. Data Status • RF01 and RF02 there was a leak in the exhaust line for the WV channel resulting in pressure/flow problems. TW data good. • RF01 – RF03: TW measurement following thick clouds was compromised by condensation on the cold hatch interface flange. • Only need to finalize uncertainty statement to submit final data • WV channel has better precision and lower uncertainty than TW

  13. Summary • NOAA Water is a new 2-channel TDL H2O instrument designed and built for GH • Measures both water vapor and enhanced total water (from which cirrus IWC can be calculated) • Utilizes in situ calibration to verify stability of instrument sensitivity and background • ATTREX 2 was a successful first deployment of the new NOAA Water instrument • Final data only awaiting final error analysis/formulation

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