Observations of surface energy fluxes and meteorology in the seasonally snow-covered high-elevation East River Watershed during SPLASH, 2021–2023

Abstract. From autumn 2021 through summer 2023, scientists from the National Oceanic and Atmospheric Administration (NOAA) and partners conducted the Study of Precipitation, the Lower Atmosphere, and Surface for Hydrometeorology (SPLASH) campaign in the East River Watershed of Colorado. One objective of SPLASH was to observe the transfer of energy between the atmosphere and the surface, which was done at several locations. Two remote sites were chosen that did not have access to power utilities. These were along the valley floor near the East River in the vicinity of the unincorporated town of Gothic, Colorado. Energy balance measurements were made at these locations using autonomous, single-level flux towers referred to as Atmospheric Surface Flux Stations (ASFS). The ASFS were deployed on 28 September 2021 at the “Kettle Ponds Annex” site and on 12 October 2021 at the “Avery Picnic” site and operated until 19 July and 21 June 2023, respectively. Measurements included basic meteorology; upward and downward longwave and shortwave radiative fluxes, and subsurface conductive flux, each at 1-minute resolution; 3-d winds from a sonic anemometer and H₂O/CO₂ from an open-path gas analyser, both at 20 Hz from which sensible, latent heat, and CO₂ fluxes were derived; and profiles of soil properties in the upper 0.5 m (both sites) and temperature profiles through the snow (at Avery Picnic), each reported between 10 min and 6 hours. For most measurements, uptime was 96 % (Kettle Ponds) and 89 % (Avery Picnic), and collectively 1,184 days of data were obtained between the stations. The purpose of this manuscript is to document the ASFS deployment at SPLASH, the data acquisition and post-processing of measurements, and to serve as a guide for interested users of the data sets, which are archived under the Creative Commons 4.0 Public Domain licensing at Zenodo.