Satellite prediction of coastal hypoxia in the northern Gulf of Mexico
Satellite prediction of coastal hypoxia in the northern Gulf of Mexico
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DOI：
10.1016/j.rse.2022.113346
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发表时间：
2023-01
影响因子：
13.5
通讯作者：
Yingjie Li;Sam Robinson;L. Nguyen;Jianguo Liu
中科院分区：
文献类型：
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作者：
Yingjie Li;Sam Robinson;L. Nguyen;Jianguo Liu
沿海缺氧的数量、规模和频率日益增加，日益威胁着海洋生态系统的健康和对人类福祉至关重要的生态系统服务。因此，迫切需要利用连续一致的观测和开发先进的工具来表征和跟踪沿海缺氧的时空变化。具有良好时空分辨率和全球覆盖的卫星图像在监测环境变化方面显示出巨大的潜力，但很少应用于缺氧制图。为了进一步了解这一点，我们综合了2014年收集的卫星海洋颜色变量和溶解氧测量数据，并使用随机森林回归、滞后线性回归和功能数据分析来估计墨西哥湾缺氧带的时空变化。这三种模型的预测精度相似（±1.2-1.4 mg/L溶解氧），但随机森林回归在从卫星衍生变量估计底部溶解氧方面表现最好。我们的模型还揭示了地表水过程（例如藻类繁殖和海洋变暖）与底层水缺氧之间大约0-5天和16-19天的时间滞后，这在以前使用卫星数据进行的缺氧研究中很少被考虑到。最后，我们的模型显示，海湾缺氧面积从5月开始逐渐增加，在2014年7月中旬和8月中旬达到峰值，缺氧区发生在密西西比河和苏万尼河河口，大约占夏季天数的25%。除了预测缺氧区的大小外，我们的研究还提供了更多关于缺氧区持续时间、地点和时间的信息，并提供了更多的空间细节，使缺氧区能够在近实时（例如，天）的时间尺度上建模。更重要的是，我们展示了应用卫星遥感进行空间明确缺氧制图的巨大潜力，这可以促进更具成本效益的沿海缺氧监测和评估实践。
The growing number, size, and frequency of coastal hypoxia increasingly threaten marine ecosystem health and essential ecosystem services for human well-being. It is therefore urgent to use continuous and consistent observation and develop advanced tools to characterize and track the spatial and temporal change of coastal hypoxia. Satellite imagery with fine spatiotemporal resolution and global coverage has shown great potential for monitoring environmental changes, yet has rarely been applied to hypoxia mapping. To advance the understanding, we synthesized satellite-derived ocean color variables and dissolved oxygen measurements collected during 2014, and used random forest regression, lagged linear regression, and functional data analysis to estimate the spatiotemporal change of the hypoxia zone in the Gulf of Mexico. The three models achieved similar predictive accuracy (±1.2–1.4 mg/L dissolved oxygen), but the random forest regression performed the best in estimating the bottom dissolved oxygen from satellite-derived variables. Our models also revealed time lags of roughly 0–5 and 16–19 days between the surface water process (e.g., algae bloom and ocean warming) and bottom water hypoxia, which was rarely considered in previous hypoxia studies using satellite data. Finally, our models showed that the area of Gulf hypoxia increased gradually from May and reached a peak during mid-July and mid-August in 2014, and the hypoxia zone occurred in the estuary of the Mississippi River and Suwannee River during roughly 25% of summer days. In addition to predicting the size of hypoxic zones, our study provides additional information on where, when, and how long hypoxic zones persist with greater spatial details and enables modeling hypoxic zones at near-real-time (e.g., days) temporal scales. More importantly, we demonstrate the great potential of applying satellite remote sensing for spatially explicit hypoxia mapping, which could promote more cost-effective coastal hypoxia monitoring and assessment practices.