Surface Quantitative Precipitation Estimates (SQUIRE) of Snow Water Equivalent from the Surface Atmospheric Integrated Field Laboratory

Journal Article · Thu Jan 01 00:00:00 EST 2026 · Journal of Atmospheric and Oceanic Technology

DOI:https://doi.org/10.1175/JTECH-D-25-0023.1· OSTI ID:3008313

Jackson, Robert ^[1]; O’Brien, Joseph ^[1]; Grover, Maxwell ^[1]; Sherman, Zachary ^[1]; Collis, Scott ^[1]; Raut, Bhupendra A. ^[1]; Tuftedal, Matt ^[1]; Theisen, Adam ^[1]; Feldman, Daniel ^[2]; Rudisill, William ^[2]; Chandrasekar, V. ^[3]

---

1. Argonne National Laboratory (ANL), Argonne, IL (United States)
2. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
3. Colorado State Univ., Fort Collins, CO (United States)

The upper Colorado River basin is the primary source of water for 40 million people. With declining snowpack in the basin, forecasting hydrological budgets in the Southwest United States is more important than ever. However, due in part, to a lack of reliable observations of precipitation in complex terrain, hydrological models struggle to assess and forecast snowpack snow water equivalent (SWE) in the upper Colorado River basin (UCRB). Therefore, the need for more reliable SWE forecasts in the UCRB motivated the U.S. Department of Energy Atmospheric Radiation Measurement Facility’s Surface Atmospheric Integrated Field Laboratory (SAIL) that occurred from June 2021 to June 2023. During SAIL, the X-band precipitation radar from Colorado State University conducted volume scans sampling the precipitation properties over the UCRB. The ARM facility developed a gridded Surface Quantitative Precipitation Estimates (SQUIRE) product from the radar observations. To do this, various daily SWE estimates from radar using the radar reflectivity factor Z_e and specific differential phase K_dp were compared against ground-based precipitation gauges. SWE in precipitation calculated from Wolfe and Snider’s S–Z_e estimator was in best agreement with the rain gauges for the days when SWE < 12 mm. For days with SWE > 12 mm, the WSR-88D Intermountain West relationship had the best agreement with the precipitation gauges. Airborne snow depth observations show that SQUIRE captures regions of orographic enhancement in the mountains to the west and northwest of the SAIL study area, indicating that the scientific community should focus on understanding and ultimately simulating orographic atmospheric precipitation processes to improve UCRB snowpack SWE assessment and forecasting.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Atmospheric Radiation Measurement (ARM) Data Center
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Contributing Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Grant/Contract Number: AC02-05CH11231; AC02-06CH11357; AC05-00OR22725
• OSTI ID: 3008313
• Journal Information: Journal of Atmospheric and Oceanic Technology, Journal Name: Journal of Atmospheric and Oceanic Technology Journal Issue: 1 Vol. 43; ISSN 0739-0572; ISSN 1520-0426
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

Related Subjects

Hydrology
Radars/Radar observations
Snow