Experiment and computational fluid dynamics simulation study on the effect of wind disturbance on the collection rate error of rainfall

Abstract The accuracy of rainfall data directly determined the precision of hydrological analysis. However, the rain gauges were observed above the ground, and the wind turbulence around the rain gauge mouth affected the accuracy of the observation data. To explore the mechanism of the influence of wind turbulence on the accuracy of rainfall collection and provide a correction formula for this error caused by wind disturbance, the field observation experiments and the CFD (Computational Fluid Dynamics) simulations were performed to analyze the mechanism of influence of wind disturbance in rainfall observation. The experimental results showed that the rain gauge collection rate was 4.3m <0.7m <ground rain gauge (0m), and the rainfall collection rate of 0.7m height rain gauge was about 95% of that of ground rain gauge. The simulation results showed that the high gradient wind velocity distortion region (the wind velocity increases by about 19%) and the vortex raceway below the distortion region were formed in the range of about 5 cm above the rain gauge collector, which caused the uneven force on the precipitation particles in this region, thus reducing the precipitation collection rate. The rainfall correction formula based on the conventional observation elements was given, which provides a theoretical basis for the correction of wind-induced rainfall error and a reference for improving the accuracy of rainfall observation.