Analysis of tipping time characteristics of tipping bucket rain gauge

During the study of the tipping bucket rain gauge (TBR), objective and sophisticated measurements of the duration of bucket rotation were difficult due to the rapid rotation speed of the bucket. In this paper, a new method of measuring the rotation time of the bucket is presented by using the inter-frame difference algorithm in image processing, combined with MATLAB software programming. The method was applied to four commonly used TBRs, and experimental research was carried out under different rain intensity scales to analyze the time characteristics of bucket rotation. The results show that: (1) The tipping time of the four TBRs used in the experiment is unstable under light rain, and the fluctuations are large; however, it is stable under heavy rain, and the fluctuations are small. (2) The tipping time of the JDZ02 and CQS·JD02 buckets decreases with increasing rain intensity, and shows a good linear relationship, with R² of 0.99 and 0.86, respectively. The linear relationship between JDZ05 and CQS·JD05 is not obvious, and R² is less than 0.6. (3) The introduction of the inter-frame difference algorithms during digital image processing can effectively obtain the time characteristics of bucket rotation, and deepen our understanding of the tipping bucket rain gauge.