Errors and adjustments for single-Alter shielded and unshielded weighing gauge precipitation measurements from WMO-SPICE

Although precipitationhas been measured for many centuries, precipitationmeasurements are still beset with significant inaccuracies. Solid precipitationis particularly difficult to measure accurately, and differences between winter-time precipitationmeasurements from different measurement networks or different regions can exceed 100 %. Using precipitationgauge results from the World Meteorological Organization Solid PrecipitationIntercomparison Experiment (WMO- SPICE), errors in precipitationmeasurement caused by gauge uncertainty, spatial variability in precipitation, hydrometeor type, crystal habit, and wind were quantified. The methods used to calculate gauge catch efficiency and correct known biases are described. Adjustments, in the form of transfer functions that describe catch efficiency as a function of air temperature and wind speed, were derived using measurements from eight separate WMO- SPICEsites for both unshielded and single-Alter shielded weighing precipitationgauges. The use of multiple sites to derive such adjustments makes these results unique and more broadly applicable to other sites with various climatic conditions. In addition, errors associated with the use of a single transfer function to correct gauge undercatch at multiple sites were estimated.