Sea fog is a critical meteorological phenomenon that affects production safety and operational efficiency at Ningbo–Zhoushan Port. To improve fine-grained sea fog forecasting in the port area, this study constructs a dynamic graph by leveraging the strengths of graph neural networks in processing irregularly distributed meteorological station data. The graph is designed based on station locations and wind direction/speed, incorporating the advection term in the atmospheric motion equation. On this basis, a novel forecasting framework is developed that integrates graph attention networks, long short-term memory, and multistep classification output, to train a sea fog forecasting model. The proposed model provides hourly rolling 24-h sea fog forecasts for 72 stations across the port area. Operational validation in 2023 demonstrates its robust performance in forecasting fog occurrence. For 24-h fog occurrence forecasts, the model achieves a threat score (TS) of 0.369 (F1 = 0.539), with an average TS of 0.190 for fixed-time forecasts. The forecasting performance exhibits a typical temporal decay pattern, reaching its highest TS (0.441) at the 1-h lead time. Furthermore, the model demonstrates superior skill in predicting localized patchy fog and fog evolution, outperforming conventional machine learning approaches such as random forest and Gaussian naive Bayes.
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This study established an S-band dual-polarization radar quantitative precipitation estimation system (NDRQPES) using raindrop size distribution (DSD) data observed during the Meiyu seasons of 2021–2023 in Ningbo, a coastal city in eastern China. The NDRQPES was evaluated by comparing its quantitative precipitation estimation (QPE) accuracy with the national radar mosaic operational product (CHN_QPE) during the Meiyu periods of 2023 and 2024. The results show that NDRQPES, incorporating linear rainfall relationships from localized DSD data, has significantly improved hourly precipitation estimate accuracy, with a correlation coefficient (CC) > 0.90 and relative bias (RB) within ±10%. Furthermore, it outperforms CHN_QPE in critical success index (CSI) across various rainfall rates. However, it exhibits biases in accumulated rainfall estimates, overestimating by 8.89% in 2023 and underestimating by 13.87% in 2024. NDRQPES is also less effective than CHN_QPE in detecting extreme heavy rainfall (> 64 mm h−1). These deficiencies may be attributed to the microphysical complexity of Meiyu rainfall, including variabi-lity in hydrometeor morphology and noise interference in weak rainfall, as well as the limited representativeness of single-point DSD data. While CHN_QPE effectively captures intense precipitation events, it exhibits significant systematic overestimation, with an RB of 161.77% in 2024. This study provides valuable insights for refining and localizing dual-polarization radar precipitation algorithms for regional applications.
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