23 Aug 2022
23 Aug 2022
Status: this preprint is currently under review for the journal AMT.

Estimation of raindrop size distribution and rain rate with infrared surveillance camera in dark conditions

Jinwook Lee, Jongyun Byun, Jongjin Baik, Changhyun Jun, and Hyeon-Joon Kim Jinwook Lee et al.
  • Department of Civil and Environmental Engineering, College of Engineering, Chung-Ang University example, Seoul, 06974, South Korea

Abstract. This study estimated raindrop size distribution (DSD) and rainfall intensity with an infrared surveillance camera in dark conditions. Accordingly, rain streaks were extracted using a k-nearest neighbor (KNN)-based algorithm. The rainfall intensity was estimated using DSD based on physical optics analysis. The estimated DSD was verified using a disdrometer. Furthermore, a tipping-bucket rain gauge was used for comparison. The results are summarized as follows. First, a KNN-based algorithm can accurately recognize rain streaks from complex backgrounds captured by the camera. Second, the number concentration of raindrops obtained through closed-circuit television (CCTV) images was similar to the actual PArticle SIze and VELocity (PARSIVEL)-observed number concentration in the 0.5 to 1.5 mm section. Third, maximum raindrop diameter and the number concentration of 1 mm or less produced similar results during the period with a high ratio of diameters of 3 mm or less. Finally, after comparing with the 15-min cumulative PARSIVEL rain rate, the mean absolute percent error (MAPE) was 44 %. The differences according to rain rate can be determined. The MAPE was 32 % at a rain rate of less than 2 mm h-1 and 73 % at a rate above 2 mm h-1. We confirmed the possibility of estimating an image-based DSD and rain rate obtained based on low-cost equipment during dark conditions.

Jinwook Lee et al.

Status: open (until 19 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-196', Anonymous Referee #1, 08 Sep 2022 reply

Jinwook Lee et al.

Jinwook Lee et al.


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Short summary
Our study addresses this by extracting rain streaks extracted using a KNN-based algorithm, estimating rainfall intensity using raindrop size distribution based on physical optics analysis, and verifying the estimated raindrop size distribution using a disdrometer. Experimentation demonstrated the possibility of estimating an image-based DSD and rain rate obtained based on such low-cost equipment in dark conditions.