RAPID: The Impact of Complex Terrain on Atmospheric Mixing through Measurements of Isotopologues of Water Vapor in the Boundary Layer

Mountainous terrain contains complex atmospheric motions that impact the formation of precipitation and the distribution of air pollution. This award is for the deployment of instruments that are capable of measuring isotopes in water vapor. Through these measurements, the researchers can determine how much mixing of air from lower elevations and higher elevations is occurring and how the mixing changes based on atmospheric conditions. The award will provide data that is important for the prediction of terrain-enhanced snowfall and the export of pollution out of mountain valleys. A graduate student will gain experience by leading the field experiment aspects of this project. This award will fund the deployment of a Picarro cavity ring-down spectrometer at the base of Mount Werner in Steamboat Springs, Colorado and a new portable instrument for measuring water vapor isotopes that will be transported to observe the changes in the isotope ratio with elevation. The deployments will be conducted in a heavily instrumented area due to the concurrent Snow Sensitivity to Clouds in a Mountain Environment (S2noCliME) field campaign in the Winter 24-25 season. In particular, an existing Picarro spectrometer hosted by Storm Peak Laboratory on Mount Werner and atmospheric balloon soundings from the campaign will be used alongside the measurements from this project to answer to key questions related to mixing: (1) What is the state of the air before it rises along the mountain slope, and (2) How does the mountain slope influence mixing between the boundary layer and residual layer/free troposphere as a function of wind direction and speed from a mid-tropospheric wind? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.