Low stratospheric water vapor measured by an airborne DIAL

The performance of a newly developed airborne water vapor DIAL system capable of measuring very low values of water vapor mixing ratios (10 ppmv) typically encountered in the lower stratosphere are presented. The instrument was tested during a series of flights where the aircraft crossed a potential vorticity streamer at about 12 km altitude. The measured cross sections show significant water vapor structures of about 5-100 ppmv within the stratospheric air of the streamer. Comparisons with fields derived from operational data show good agreement in water vapor structures and magnitude. Comparisons with precise aircraft in situ measurements agree within 7%