A New Precipitation Monitoring System: Image Disdrometer
Abstract
The ground observation of rainfall intensity and particle size of raindrops are important in meteorological studies and hydrological processes. The accurate measurement of precipitation currently requires expensive rain gauges or laser monitoring systems, with which it is difficult to expand the number of ground-based observation. In this study, a new, small, and simple ground rainfall measurement system named "image disdrometer" was developed. The observational system consists of a small container covered with a transparent acrylic plate which receives raindrops, a small wiper to regularly remove raindrops on the plate and a widely-used compact video camera placed on the bottom of the container to take time-series images of the acrylic plate to which raindrops attach. In the data analysis, the consecutive images are processed to detect raindrops. At each frame, the particle size of the detected raindrops and the number of the drops are calculated to estimate rainfall intensity and particle size distribution.
To examine the applicability of image disdrometer, the system was tested with a laser precipitation monitor verified along ISO 9001 under actual rain in the spring of 2019. The results showed that the 1 min rainfall intensity measured by image disdrometer was precise with the root mean square error of 0.66 mm h-1 and the temporal variation agreed well with the one observed by the laser precipitation monitor. The particle size of raindrops obtained by image disdrometer was distributed from 0.250 to 4.000 mm with the highest frequency in the range of 0.750 - 1.000 mm. That was slightly overestimated compared to the results of the laser monitoring that the particle size ranged from 0.125 to 3 mm with the most frequency between 0.500 and 0.750 mm. Despite the overestimation, the particle size distribution based on image disdrometer was very close to the one taken by the laser precipitation monitor. These results show that image disdrometer has performance comparable to the commonly-used measurement system. Image disdrometer is simple and affordable, and can be an alternative of currently-prevailing precipitation monitoring systems.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H33K2082O
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 1816 Estimation and forecasting;
- HYDROLOGY;
- 1817 Extreme events;
- HYDROLOGY;
- 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDS