Dual-Gauge System for Measuring Precipitation: Historical Development and Use

Undercatch of precipitation due primarily to wind is especially pronounced when measuring snowfall by gauges that are not naturally protected, such as in brush or forest clearings. The dual-gauge system can be used to measure all types of precipitation, but was designed specifically to improve the measurement of snowfall under windy conditions. The dual-gauge system uses sets of unshielded and shielded gauge data and an appropriate value of a calibration coefficient in an equation to calculate wind-adjusted precipitation. After three winter seasons of field studies in Idaho, it was determined that 1.8 was the most appropriate value for the calibration coefficient. Analyses of data from other sites in the United States, Canada, and Russia also show that 1.8 is the most reasonable value to use for the calibration coefficient when calculating wind-adjusted snowfall amounts, and that the dual-gauge system also significantly improves the measurement of other forms of precipitation. These studies led to the development of procedures for estimating “ground true” precipitation when only single unshielded or shielded gauge data are available.