SAIL-ISO

Water vapor isotopic measurements during SAIL

15 June 2022 - 15 June 2023

Lead Scientist: Joseph Galewsky

Observatory: AMF (ARM Mobile Facility 2) - GUC

This project seeks to use measurements of the stable isotopic composition of water vapor during the ARM SAIL experiment in the Crested Butte area of Colorado to better understand 1) the processes that govern the distribution, phase, amount, and intensity of precipitation in a region of complex topography and (2) the influences of snow sublimation on snowpack water and energy balance. The stable isotopic composition of atmospheric water vapor in this setting is expected to reflect the balance between orographic circulations, precipitation processes, and surface fluxes. A particularly exciting aspect of joining the SAIL campaign is the opportunity to use water vapor isotopologues to probe orographic precipitation processes. These processes likely affect the isotopic composition of water vapor through equilibrium fractionation of liquid droplets, kinetic fractionation of ice particles, and the evaporation or sublimation of hydrometeors. We expect that seeder-feeder processes may have distinctive isotopic signatures via the enhancement of low-level precipitation from precipitation at higher levels. We also anticipate that orographic flows will mix water vapor from different reservoirs aloft and from surface fluxes, yielding distinctive isotopic signatures that may help to disentangle the links between orographic circulations and precipitation processes. The suite of instruments to be deployed during SAIL will enable us to advance our understanding of how convective processes influence water vapor and its isotopologues; furthermore, we expect that the isotopic measurements will provide new insights into the more conventional meteorological measurements that will be made during the project.