Intercomparison measurements from commonly used precipitation gauges in the Qilian Mountains

Abstract

Precipitation data is vital fundamental data for climate change. However, obtaining precise gauge-measured precipitation in high-altitude mountains is challenging, and the precipitation obtained from various gauge types at the same station may vary. To understand the differences in precipitation observations among the three commonly used gauges in China (Chinese Standard Precipitation Gauges (CSPG), Total Rain weighing Sensor (TRwS), and Geonor T-200B (T200B)) in high-altitude mountains and to recommend a stable and cost-effective weighing gauge, a precipitation intercomparison experiment was conducted at Hulu-1 station in the Qilian Mountains. The wind-induced error in measurement was corrected with the ‘universal’ transfer function recommended by the Word Meteorological Organization. The comparison results, adjusted for systematic errors, showed that the rain, snow and mixed precipitation of CSPG and TRwS equipped with the same octagonal vertical double fence shields (CSPGDF and TRwSDF) and single-Alter shields (CSPGs and TRwSs) were close, while the precipitation of Tretyakov-shielded T200B was notably higher than that of CSPGs and TRwSs. The average differences in annual and daily precipitation between CSPGDF and TRwSDF from 2017 to 2021 were 12.9 mm and 0.10 mm, respectively. The daily precipitation difference between CSPGs and TRwSs from April 2019–December 2021 was 0.10 mm, while the differences between T200Bs and CSPGs and TRwSs was 0.28 mm and 0.38 mm, respectively. The wind shield performance of Alter and Tretyakov was not much different at Hulu-1 site with low wind speed, thus the measurement principle of T200Bs was the primary cause of the high observations. Taking the corrected CSPGDF measurement as the standard, the dynamic loss of CSPGs was 17.6%, while that of CSPGUn was 55.6%, indicating that the single-Alter shield could effectively reduce the impact of wind on precipitation measurement. Considering the comparison results and the price difference of the instruments, it was recommended to use a single-Alter shielded TRwS gauge for precipitation observation in high-altitude mountains.