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

Sample and calibration flow schematic

P Optical absorption cell 39 cm physical path, 78 cm optical path 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

TDL scan Scan approximately 1 cm -1 at 10 Hz, co-average spectra to 1 Hz Two H 2 O lines with a factor of ~20 difference in line strength One or two CO 2 lines

Inlet pylon 27 cm 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

WV inlet particle rejection Inlet perpendicular to flow stream to prevent sampling of cloud particles Design used successfully in the past with CIMS H 2 O and SP2 (MACPEX), CIMS HNO 3 Curve based on empirical study reported by Brixey et al., 2004 – application requires extrapolation from low U/U 0

TW inlet enhancement factor Function of airspeed, pressure, temperature, volumetric sample flow, particle density In TTL, typical values: – U = 4.47 m/s, U 0 = 180 m/s Based on CFD models from Krämer and Afchine, 2004 and Eddy et al., 2006

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

In-flight calibration In-flight calibration used to assess stability of sensitivity Range of mixing ratios generated by H 2 oxidation on Pt catalyst Only WV channel calibrated

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

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

Summary NOAA Water is a new 2-channel TDL H 2 O 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