A new rainfall nowcasting method by introducing the attention mechanism into the ConvGRU deep learning model
摘要
Accurate rainfall nowcasting plays a vital role in flood control, agricultural planning, and climate research. However, the inherently nonlinear, highly variable, and spatiotemporally complex nature of precipitation poses considerable challenges for achieving reliable short-term forecasts. Conventional deep learning approaches, such as Convolutional Neural Networks (CNNs), Long Short-Term Memory (LSTM) networks, and Gated Recurrent Units (GRUs), often fail to capture the intricate temporal and spatial dependencies in precipitation data, particularly in regions with complex topography. To address these limitations, this study proposes AE-ConvGRU, an enhanced ConvGRU-based architecture that integrates a multi-head attention mechanism with feature enhancement strategies for early fusion of multimodal meteorological data, specifically Precipitable Water Vapor (PWV) and rainfall observations. The model adaptively assigns dynamic weights to highlight key spatial features and improve the representational capacity of fused data. Using ERA5 reanalysis datasets from 2019 to 2024 over Zhejiang Province, China, the AE-ConvGRU model was trained on multi-year data and evaluated on independent 2024 data. Six standard metrics, including the Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), and the coefficient of determination R2, were used for performance assessment. Experimental results demonstrate that AE-ConvGRU achieved a one-hour rainfall prediction RMSE of 0.339 mm, representing a 27.10%, 24.16%, 13.96%, and 5.04% improvement over the CNN, GRU, XGBoost, and ConvGRU models, respectively. Moreover, the proposed method achieved average improvements of 23.11% for MAE and 72.18% for R2 compared with four traditional methods. Additionally, AE-ConvGRU exhibited robustness in capturing rainfall patterns under both heavy and light precipitation scenarios, demonstrating superior ability to model spatial distribution and temporal evolution. These findings confirm the effectiveness of attention-guided multimodal fusion and highlight the potential of AE-ConvGRU as a powerful tool for accurate and stable short-term rainfall nowcasting.