Isotopic Fractionation in Snow (IFRACS) at Storm Peak Laboratory

Abstract:

The conditions at Storm Peak Laboratory in Steamboat Springs, Colorado (USA) during the IFRACS experiment of Jan-Feb 2014 are simulated using a version of the Weather Research and Forecasting (WRF) model with water isotopologues (HDO and H2O18) integrated into the microphysics. During IFRACS, measurements of the isotopic composition of vapor, cloud liquid and snowfall at Storm Peak Lab were gathered along with meteorological and cloud microphysics data. These data, and satellite observations of the isotopic composition of water vapor aloft, are used to evaluate the model simulations. The simulations, in turn, inform the large- and meso-scale conditions that produce the observations at Storm Peak.

A main goal of IFRACS is to understand the extent to which aerosols can impact the isotopic composition of snowfall from mixed-phase orographic clouds. Model simulations with varying prescribed cloud droplet number concentrations (as a proxy for aerosol variations) explore the response of snowfall and its isotopic composition to these changes.