The Relationships Between Snowfall Catch Efficiency and Wind Speed for the Geonor T-200B Precipitation Gauge Utilizing Various Wind Shield Configurations

Most precipitation gauges experience a significant systematic bias in the measurement of snowfall during windy conditions. This bias can be reduced by utilizing various wind shield configurations around the precipitation gauge, but the measurement error for snowfall during windy events often remains substantial and requires an adjustment. To adjust snowfall measurements made by the Geonor T-200B, the relationship between gauge (and wind shield) catch efficiency and wind speed at gauge height must be derived. The most accepted methodology is to compare the catch of the gauge to that of the World Meteorological Organization reference for solid precipitation, the Double Fence Intercomparison Reference (DFIR). Using the precipitation gauge intercomparison facility at Bratt's Lake SK, Catch Efficiency - Wind Speed relationships have been developed for the Geonor T-200B gauge utilizing single Alter, double Alter, and a large octagonal double fence (similar to the DFIR) wind shields. The Geonor T-200B catch efficiency for snowfall typically drops off exponentially with increasing wind speed at gauge height. Of the shielded gauges that were compared to the DFIR, the single Alter exhibits the lowest catch efficiency followed by the double Alter.