Abstract
Abstract. Although precipitation has been measured for many centuries, precipitation measurements are still beset with significant inaccuracies. Solid precipitation is particularly difficult to measure accurately, and wintertime precipitation measurement biases between different observing networks or different regions can exceed 100 %. Using precipitation gauge results from the World Meteorological Organization Solid Precipitation Intercomparison Experiment (WMO-SPICE), errors in precipitation measurement 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-SPICE sites for both unshielded and single-Alter-shielded precipitation-weighing gauges. For the unshielded gauges, the average undercatch for all eight sites was 0.50 mm h−1 (34 %), and for the single-Alter-shielded gauges it was 0.35 mm h−1 (24 %). After adjustment, the mean bias for both the unshielded and single-Alter measurements was within 0.03 mm h−1 (2 %) of zero. 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.
Highlights
IntroductionPrecipitation is subject to the observer effect, whereby the act of observing affects the observation itself
Like many atmospheric measurements, precipitation is subject to the observer effect, whereby the act of observing affects the observation itself
Kochendorfer et al.: Analysis of single-Alter-shielded and unshielded measurements wind speed; wind shielding; the shape of the precipitation gauge; and the predominant size, phase, and fall velocity of the hydrometeors (Colli et al, 2015; Folland, 1988; Groisman et al, 1991; Theriault et al, 2012; Wolff et al, 2013). Because all these factors affect the amount of undercatch, it is difficult to accurately describe and adjust the resultant errors for all gauges, in all places, in all types of weather. This has been an active area of research for over 100 years (e.g. Alter, 1937; Heberden, 1769; Jevons, 1861; Nipher, 1878), with significant findings for manual measurements described in the World Meteorological Organization (WMO) precipitation intercomparison experiment performed in the 1990s (Goodison et al, 1998; Yang et al, 1995, 1998b)
Summary
Precipitation is subject to the observer effect, whereby the act of observing affects the observation itself. Kochendorfer et al.: Analysis of single-Alter-shielded and unshielded measurements wind speed; wind shielding; the shape of the precipitation gauge; and the predominant size, phase, and fall velocity of the hydrometeors (Colli et al, 2015; Folland, 1988; Groisman et al, 1991; Theriault et al, 2012; Wolff et al, 2013) Because all these factors affect the amount of undercatch, it is difficult to accurately describe and adjust the resultant errors for all gauges, in all places, in all types of weather. The ultimate goal of all this research is to facilitate the creation of accurate and consistent precipitation records spanning different climates and different measurement networks, including measurements by different gauges and shields (e.g. Førland and Hanssen-Bauer, 2000; Scaff et al, 2015; Yang and Ohata, 2001)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
