Evaluation of snow gauges used in a winter cloud seeding experiment in complex terrain

Accurate measurements of liquid water equivalent snowfall amounts are critical when attempting to quantify the effects of cloud seeding over an area, particularly in complex terrain. The most common method for measuring liquid-equivalent amounts is through the use of a snow gauge. It is well known that snow gauges, located above ground and freely exposed to the wind, will consistently collect lesser amounts of precipitation as compared to gauges protected from the wind. Precipitation gauges located above ground are themselves an obstacle to the wind, modifying the airflow pattern and consequently altering the trajectories of hydrometeors, particularly snow, making accurate measurements of snowfall challenging. Many different styles of snow gauges are commercially available ranging from heated tipping buckets to strain gauges to weighing gauges. The ongoing weather modification experiment being conducted in Wyoming has required the use of snow gauges installed in the Medicine Bow and Sierra Madre mountain ranges. Multiple styles of snow gauges are being used for the study and the advantages and shortcomings of each gauge, both hardware and software, are examined in this paper.