Summary of and Selected Highlights from the Surface Atmosphere Integrated Field Laboratory (SAIL) Field Campaign

The U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) program deployed the Second ARM Mobile Facility as part of the Surface Atmosphere Integrated Field Laboratory (SAIL) Campaign from September 1, 2021 to June 15, 2023. The main goal of the deployment is to advance the predictive understanding of the atmospheric processes driving the mountain hydrology of the Upper Colorado River Basin (UCRB) by collecting a broad suite of observations of the dominant processes that impact how the atmosphere, surface and sub-surface work in tandem to produce water resources for the 40 million people and thousands of ecosystems that rely. The Campaign, spread across three locations near Crested Butte, Colorado collected well over 100 different datastreams that are currently available for download at ARM Data Discovery, and, broadly speaking, tracked two very active water years that began with a record-setting drought and ended drought-free. Measurements of precipitation, aerosols, radiation, winds, and atmospheric thermodynamics, showed the temporal and spatial evolution of the atmosphere as it busted the drought. The Campaign was also marked by extreme collaboration: SAIL began in close collaboration with the DOE-sponsored Watershed Function SFA, but blossomed into much more: ARM, as a National User Facility, hosted over one dozen guest instruments at SAIL, and the SAIL Campaign catalyzed a half-dozen deployments of the Tethered Balloon System to characterize vertical profiles of aerosols, and two major federally (non-DOE) sponsored field campaigns. NOAA’s Study of Precipitation, the Lower Atmosphere and Surface for Hydrometeorology (SPLASH) and NSF’ Sublimation of Snow (SOW) Campaigns collected complementary measurements that together created a density of observations that will enable a detailed understanding of the atmospheric processes that impact mountain hydrometeorology and hydroclimate. A brief showcase is presented of some of the mysteries that the scientific community will explore with SAIL data now that data collection is complete and the analysis phase of the Campaign begins in earnest.