ATDD researchers are helping lead new, cutting-edge research focused on the accurate measurement of precipitation. All-weather precipitation gauges are designed to accurately measure the liquid equivalent of precipitation in all phases, including both snow and rain. Snowfall, however, is particularly difficult to measure accurately due to challenges such as capping of the gauge, the high precision required to resolve typically low-rate snowfall events, and under-sampling due to wind effects.
At the joint National Center for Atmospheric Research/NOAA testbed near Boulder, CO, we have tested and intercompared many different types of windshields and precipitation gauges over the past eight years. As an active participant in the international, World Meteorological Organization (WMO) Solid Precipitation Intercomparison Experiment (SPICE), ATDD scientists have also created and tested corrections for the wind-induced under-sampling of precipitation at sites all over the world. This research includes data from many different types of precipitation gauges and windshields from all over the world. These corrections can be used to estimate the true amount of precipitation where the measured precipitation may be underestimated by over 50% in windy, snowy conditions. These corrections help improve precipitation measurements and create more accurate hydrological budgets, and they can also be used to better intercompare and homogenize precipitation measurements made across different periods in time, different climates, and different measurement networks.
WMO-SPICE scientists standing in front of a
reference precipitation windshield in the Spanish Pyrenees
Wind tunnel measurements show how the flow of wind over the mouth of a precipitation gauge may impact the instrument’s capture of light rain or snow.