Based on radar echo nowcasting products generated by an artificial intelligence (AI) model, two methods are used to convert echo nowcasts into precipitation predictions. One method utilizes raindrop size distribution data to fit the local Z-R relationship, while the other applies a self-adaptive Z-R relationship to link the nowcasted echo with real-time precipitation observations. The precipitation nowcasts generated by both methods are validated and evaluated using six rainstorm events that occurred in Chongqing in 2022.The results show that, for rainfall intensities of ≥ 0.6 mm/h, ≥1.6 mm/h, and ≥7.0 mm/h, both methods outperform the original extrapolation techniques to varying degrees. For the method based on raindrop size distribution data, the mean absolute improvement is 3.03%, and the mean relative improvement is 6.85%. The self-adaptive Z-R method shows a mean absolute improvement of 4.20% and a mean relative improvement of 14.46%, indicating its superior performance in forecasting heavy precipitation. this method has been incorporated into Chongqing's local operational system to generate real-time precipitation nowcast products, which play a crucial role in monitoring and nowcasting heavy precipitation events.
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