论文标题
无缝的闪电与反复跨趋势深度学习
Seamless lightning nowcasting with recurrent-convolutional deep learning
论文作者
论文摘要
提出了一个深度学习模型，以便在未来60分钟的五分钟时间分辨率下以五分钟的时间分辨率进行闪电的发生。该模型基于反复横向构造的结构，该结构使其能够识别并预测对流的时空发展，包括雷暴细胞的运动，生长和衰变。预测是在固定网格上执行的，而无需使用风暴对象检测和跟踪。从瑞士和周围的区域收集的输入数据包括地面雷达数据，可见/红外卫星数据以及衍生的云产品，闪电检测，数值天气预测和数字高程模型数据。我们分析了不同的替代损失功能，班级加权策略和模型特征，为将来的研究提供了指南，以最佳地选择损失功能，并正确校准其模型的概率预测。基于这些分析，我们在这项研究中使用焦点损失，但得出结论，它仅比横熵提供了很小的好处，如果模型的重新校准不实用，这是一个可行的选择。该模型在60分钟的现有周期内实现了0.45的像素临界成功指数（CSI）为0.45，以预测8 km的闪电发生，范围从5分钟的提前时间为0.75，到60分钟的提前时间CSI的CSI到0.32的CSI。
A deep learning model is presented to nowcast the occurrence of lightning at a five-minute time resolution 60 minutes into the future. The model is based on a recurrent-convolutional architecture that allows it to recognize and predict the spatiotemporal development of convection, including the motion, growth and decay of thunderstorm cells. The predictions are performed on a stationary grid, without the use of storm object detection and tracking. The input data, collected from an area in and surrounding Switzerland, comprise ground-based radar data, visible/infrared satellite data and derived cloud products, lightning detection, numerical weather prediction and digital elevation model data. We analyze different alternative loss functions, class weighting strategies and model features, providing guidelines for future studies to select loss functions optimally and to properly calibrate the probabilistic predictions of their model. Based on these analyses, we use focal loss in this study, but conclude that it only provides a small benefit over cross entropy, which is a viable option if recalibration of the model is not practical. The model achieves a pixel-wise critical success index (CSI) of 0.45 to predict lightning occurrence within 8 km over the 60-min nowcast period, ranging from a CSI of 0.75 at a 5-min lead time to a CSI of 0.32 at a 60-min lead time.
