Oceanic Front Detection Model Based on U-Net Network
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摘要: 海洋锋作为海洋中两种不同性质的水体之间的边界,对渔业和海洋环境保护等许多领域有重要影响,如何快速准确实现海洋锋的自动检测和识别对于海洋监测和预报具有重要的科学意义。将深度学习图像分割网络与提取锋面特征的方法相结合,利用基于U-Net架构的实例分割模型,分别建立海洋锋区和锋面中心线的智能检测模型,同时在编解码过程中采用残差学习单元对模型特征提取网络进行改进。研究结果表明,锋面智能检测模型能够准确提取先前锋面检测算法所识别的锋区和锋面中心线特征,Dice系数分别达到了0.92和0.97,达到了很好的检测效果。同时,利用不同锋面阈值得到的样本数据对模型进行训练,比较结果表明,降低样本集阈值之后模型精度有了显著的提升。Abstract: As a boundary of two water masses with different properties, oceanic fronts have important influences on many fields such as fishery, marine military and environmental protection. How to quickly and accurately implement automatic detection and identification of ocean front is of great scientific significance for ocean monitoring and forecasting. In this paper, the deep learning image segmentation network is combined with the method of extracting frontal features, and the detection models of frontal area and frontal line are established by using U-Net architecture. Meanwhile, the residual unit is used to improve the feature extraction network in the processes of encoding and decoding. The results show that the deep learning frontal detection model can accurately extract the features of frontal area and frontal line. The Dice coefficients reach 0.92 and 0.97 respectively, achieving a good detection performance. In this paper, the model is trained by the sample data of different frontal thresholds. The comparison results show that the accuracy of model is significantly improved after the threshold of sample set is reduced.
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Key words:
- Oceanic fronts /
- Sea surface temperature /
- Deep learning /
- U-Net
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图 4 (a)(b)测试集2017年第139天的SST及其梯度分布。(c)~(e)为锋区检测模型结果(0表示背景,1表示锋面),(f)~(h)为锋面中心线检测模型结果(0表示背景,1表示锋面)
Figure 4. (a) (b) SST in Day 139 in 2017 and SST gradient. (c)~(e) are frontal area model results (0 expresses backgroud, 1 expresses front); (f)~(h) are frontal line model results (0 expresses backgroud, 1 expresses front)
表 1 4种模型测试集的评价指标
Table 1. Evaluation metrics of four models in the test set
Model name Categorical accuracy Weighted Dice SST vs. area 0.9801 0.9238 Tgrad vs. area 0.9785 0.9182 SST vs. line 0.9973 0.8893 Tgrad vs. line 0.9966 0.8923 表 2 exp_bases实验中4种模型测试集的评价指标
Table 2. Evaluation metrics of four models in the test set of exp_base
Model name ctrl exp_base SST vs. area 0.9238 0.9791 Tgrad vs. area 0.9182 0.9831 SST vs. line 0.8893 0.9219 Tgrad vs. line 0.8923 0.9468 -
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