Water Vapor Isotopic Analyzer

Short Name or Variable Name

The NCAR fast water vapor isotopic analyzer (WVISO) is a Picarro L2130-i cavity ringdown spectrometer that measures the concentration of water vapor and its hydrogen and oxygen isotope ratios (δD and δ18O, respectively). The isotopic measurements provide critical insight into the moisture transport processes that set the humidity observed.

Measurements Provided: Water vapor volume mixing ratio, isotope ratio of oxygen (δ18O), isotope ratio of hydrogen (δD)

Typical Sampling Rates: 1-5 Hz

Measurement Characteristics: The instrument operates at 5 Hz frequency with a factory determined isotopic precision of 2 permil for δD and 0.5 permil for δ18O at low water vapor concentrations (2500 ppm). Precision improves with humidity, and total uncertainties in water vapor concentration are 1% or better.

Example(s) of Measurement: In addition to having flown on the NOAA P3 as part of EUREC4A, WVISO also successfully deployed during winters 2019 and 2022 at the high-altitude Storm Peak Laboratory in Colorado, to study the isotopic composition of mixed-phase clouds, on the NCAR GV during SPICULE 2021, and on the NASA P3 as part of IMPACTS 2022.

Lead Contact
Adriana Bailey
Typical Sampling Rates
1-5 Hz