基于FY-3D MWRI数据的轮廓感知海表温度重建网络

A contour-aware reconstruction network for gap-free SST from FY-3D MWRI observations

  • 摘要: 海表温度(SST)是影响天气气候变化的重要因子。在广袤的海洋区域,卫星反演数据是构成全球SST的主要来源。然而在反演算法未针对全天气条件进行优化设计的情况下,频繁的云层覆盖可能导致数据质量下降或失效。此外,极轨卫星扫描带间的固有成像间隙会形成大范围SST空白区。为填补这些数据空缺,提出专用于优化SST空间分布的轮廓感知数据重建网络(CARNet),该算法利用大陆轮廓先验知识消除海陆混合视场,采用图像膨胀技术增强大范围缺测区边缘梯度学习能力,并根据SST变化的区域差异性,在损失函数中增加经纬向梯度物理约束以保持SST的经向和纬向分布规律。将该算法应用于2023年全年风云三号卫星微波辐射计(FY-3D MWRI)SST产品,重建出覆盖南北纬60°区间、具有全球覆盖能力的每日两次无空白SST数据集。评估结果表明:修复方法能够还原局部洋流区(如赤道不稳定波、墨西哥湾暖流)的中尺度涡旋结构,抑制了热带冷舌区的正偏差。具体而言,春季日平均误差从0.8 ℃ 减小到0.5℃左右,全球SST修复后日均数据标准差降低0.1℃;修复资料再现了2023年厄尔尼诺事件的发展过程,其计算的Nino3.4指数与再分析资料有很好的相似性。该方法显著提升了FY-3D 卫星MWRI 资料反演SST产品的可用性,可以为海洋气象研究提供可靠数据支持。

     

    Abstract: Sea Surface Temperature (SST) is a pivotal driver of weather and climate. Across the vast oceans, satellite-derived retrievals provide the primary source of global SST data. Yet frequent cloud cover can result in poor or invalid SST data if the retrievals are not well designed and work under all weather conditions. In addition, the inherent imager gaps between polar-orbiting satellite scan swaths leave extensive SST voids. To fill these SST data voids, the present work proposes a Contour-Aware Reconstruction Network (CARNet) specifically designed for improving spatial SST distributions. To achieve this, the continental contour is first utilized to eliminate the land-sea mixing field of views. The morphological dilation operators are then developed to enhance edge-gradient learning capabilities for extensive missing regions. The zonal and meridional gradient constraints are integrated into the loss function to preserve latitudinal-longitudinal SST distribution patterns. This algorithm is applied to FY-3D MWRI-derived SST products from January to December 2023 to reconstruct a gap-free, twice-daily SST dataset spanning 60°S—60°N with global coverage. Evaluation demonstrates that the proposed reconstruction method accurately restores mesoscale eddy features in dynamic current systems (e.g., tropical instability waves, Gulf Stream) while reducing positive biases in tropical cold tongues. Specifically, spring SST daily mean errors decrease from 0.8℃ to approximately 0.5℃, with a concurrent reduction of 0.1℃ in global daily SST standard deviation. The reconstructed dataset characterizes the evolutionary dynamics of the 2023 El Niño event, with computed Nino3.4 indices demonstrating high consistency with reanalysis benchmarks. This approach significantly enhances the operational usability of SST products retrieved from FY-3D MWRI data, providing reliable data support for ocean-atmosphere research.

     

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