PMDRnet: A Progressive Multiscale Deformable Residual Network for Multi-Image Super-Resolution of AMSR2 Arctic Sea Ice Images

The extent of the area covered by polar sea ice is an important indicator of global climate change. Continuous monitoring of Arctic sea ice concentration (SIC) primarily relies on passive microwave images. However, passive microwave images have coarse spatial resolution, resulting in SIC production with significant blurring at the ice-water divides. In this article, a novel multi-image super-resolution (MISR) network called progressive multiscale deformable residual network (PMDRnet) is proposed to improve the spatial resolution of sea ice passive microwave images according to the characteristics of both passive microwave images and sea ice motions. To achieve image alignment with complex and large Arctic sea ice motions, we design a novel alignment module that includes a progressive alignment strategy and a multiscale deformable convolution alignment unit. In addition, the temporal attention mechanism is used to adaptively fuse the effective spatiotemporal information across image sequence. The sea ice-related loss function is designed to provide more detailed sea ice information of the network to improve super-resolution performance and further benefit finer Arctic SIC results. Experimental results demonstrate that PMDRnet significantly outperforms the current state-of-the-art MISR methods and can generate super-resolved SIC products with finer texture features and much sharper sea ice edges. The code and datasets of PMDRnet are available at https://doi.org/10.5061/dryad.k3j9kd590.