Weekly High Resolution Multispectral and Thermal UAS Mapping of an Alpine Catchment During Summer Snowmelt, Niwot Ridge, Colorado

Abstract. Alpine ecosystems are experiencing rapid change, as a result of warming temperatures and changes in the quantity, timing and phase of precipitation. This in turn impacts patterns and processes of ecohydrologic connectivity, vegetation productivity, and water provision to downstream regions. The fine scale heterogeneous nature of these environments makes them challenging areas to measure with traditional instrumentation, and spatiotemporally coarse satellite imagery. This paper describes the data collection, processing, accuracy assessment, and availability, of a series of ~weekly interval unmanned aerial system (UAS) surveys, flown over the Niwot Ridge Long Term Ecological Research site during the 2017 summer snowmelt season. Visible, near infrared, and thermal infrared imagery were collected. Our unique series of 5–25 cm multispectral and thermal orthomosaics provide a unique snapshot of seasonal transitions in a high alpine catchment. Weekly radiometrically calibrated Normalized Difference Vegetation Index imagery can be used to track vegetation productivity at the pixel scale through time. Thermal imagery can be used to map the movement of snow melt across and within the near subsurface, as well as identify locations where groundwater is discharging to the surface. A 10 cm digital surface model and dense point cloud are also provided for topographic analysis of the snow free surface. Data summaries, citations, and DOIs are provided in the Data Availability section. These datasets augment ongoing data collection within this heavily studied and important alpine site, and are made publicly available to facilitate wider use by the research community.