Seasonal Variability within Quantitative Precipitation Estimates for the Surface Atmosphere Integrated Field Laboratory (SAIL) Field Experiment

The Surface Atmospheric Integrated Field Laboratory (SAIL) field experiment is designed to advance the understanding of the water cycle within complex terrain, specifically the relationship between precipitation and river runoff within a portion of the Upper Colorado River Basin, known as the East River Watershed. With the goal of accurately estimating precipitation, the Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) Second Mobile Facility (AMF2) is stationed in Crested Butte, Colorado from September 2021 to June 2023 collecting observations with a scanning X-Band dual-polarimetric radar provided by Colorado State University (CSU) and supported by ARM. As the CSU X-Band radar is located within complex terrain, additional data processing using the Corrected Moments in Antenna Coordinates package (CMAC) provided a quality assured dataset, which includes correction for beam blockage and clutter removal. The CMAC processing also includes calculation of precipitation estimates through the relation of observed equivalent reflectivity factor (Ze) to snowfall rates (S), or rainfall rates (R), for the corrected observations. Utilizing the Python-ARM Radar Toolkit (Py-ART), analysis of the Surface QUantitative pRecipitation Estimate (SQUIRE) product will investigate the winter seasonal variability within snowfall estimates within the Upper Colorado River Basin. Emphasis will be placed on contrasting seasonal spatial variability of snowfall accumulation within the domain. Additionally, analysis of the Extract Radar Column and In-situ sensors (RADCLSS) product will allow for verification of selected empirical relationships used within precipitation estimates through comparison of daily accumulations against AMF2 in-situ instrumentation. Finally, analysis of the RADCLSS product will allow for the contrast of microphysical snowfall characteristics between seasons.