Dual-Branch State-Displacement Network for Sea Surface Temperature Super-Resolution
Organizations: State Key Laboratory of Physical Oceanography, and also with the Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao 266100, China · State Key Laboratory of Physical Oceanography, Institute of Oceanographic Instrumentation, Shandong Academy of Sciences, Qingdao 266100, China · Department of Electrical and Computer Engineering, Mississippi State University, Starkville, MS 39762 USA
Abstract
Sea surface temperature (SST) is a critical indicator of global climate change, yet satellite-derived SST imagery often suffers from coarse spatial resolution, limiting the ability to capture fine-scale thermal structures such as ocean fronts. To address this, we propose a Dual-Branch State-Displacement Network (DBSD-Net) for SST super-resolution. DBSD-Net adopts a dual-branch architecture: a wavelet frequency branch that explicitly separates low and high-frequency components via discrete wavelet transform for targeted processing, and a VGGUNet branch that extracts multi-scale semantic features from a frozen pre-trained VGG backbone. Within the wavelet branch, we introduce a Structural State Space Module (SSSM) with a Gated Structure Refinement (GSR) unit to efficiently capture long-range dependencies and enhance structural integrity, and a Displacement Gate Module (DGM) that learns a displacement field for geometry-aware modulation of high-frequency details, thereby mitigating spatially varying degradation. Experiments on multiple public SST datasets demonstrate that DBSD-Net outperforms existing state-of-the-art methods.
Figures & tables
| Configuration | PSNR (dB) | SSIM | Params (M) |
| PT-Frozen | 46.57 | 0.9909 | 30.59 |
| Random-Frozen | 46.53 | 0.9909 | 30.59 |
| PT-Trainable | 46.52 | 0.9908 | 43.80 |
| Random-Trainable | 46.51 | 0.9907 | 43.80 |
| Number of Channels | PSNR | SSIM | FLOPs (G) | Params (M) |
| 32 | 43.14 | 0.9713 | 2.31 | 2.39 |
| 48 | 44.39 | 0.9816 | 5.74 | 5.27 |
| 64 | 45.23 | 0.9853 | 13.32 | 9.29 |
| 96 | 46.84 | 0.9918 | 52.03 | 20.70 |
| 128 | 47.35 | 0.9930 | 147.48 | 36.68 |
| 144 | 47.39 | 0.9941 | 228.53 | 46.30 |
| Number of WGSG | PSNR | SSIM | FLOPs (G) | Params (M) |
| 6 | 46.94 | 0.9922 | 74.29 | 18.42 |
| 8 | 46.76 | 0.9925 | 98.69 | 24.51 |
| 10 | 47.05 | 0.9925 | 123.08 | 30.59 |
| 12 | 46.87 | 0.9924 | 147.48 | 36.68 |
| 16 | 46.86 | 0.9922 | 196.27 | 48.85 |
| Method | FLOPs | Params | Memory | Latency | Throughput |
| (G) | (M) | (MiB) | (ms) | (images/s) | |
| EDSR [ 71 ] | 18.30 | 1.37 | 90.5 | 1.55 | 1586.66 |
| CRAN [ 72 ] | 73.31 | 8.00 | 167.0 | 8.32 | 480.77 |
| ELAN [ 43 ] | 29.57 | 1.43 | 138.5 | 22.13 | 180.75 |
| DAT [ 73 ] | 52.08 | 5.22 | 269.8 | 21.89 | 182.77 |
| SAFM [ 74 ] | 51.40 | 5.56 | 189.6 | 5.31 | 553.52 |
| Method | SR scale | NP | AGM | EWP | NIO | ||||
| PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | ||
| EDSR [ 71 ] | ×2 | 36.95 | 0.9837 | 45.63 | 0.9893 | 43.93 | 0.9928 | 37.64 | 0.9813 |
| ×3 | 31.34 | 0.9651 | 39.72 | 0.9812 | 37.25 | 0.9736 | 33.89 | 0.9685 | |
| ×4 | 29.77 | 0.9341 | 38.57 | 0.9771 | 32.16 | 0.9332 | 32.31 | 0.9465 | |
| CRAN [ 72 ] | ×2 | 37.63 | 0.9871 | 45.96 | 0.9903 | 44.43 | 0.9950 | 37.92 | 0.9853 |
| ×3 | 31.34 | 0.9651 | 39.72 | 0.9812 | 37.25 | 0.9736 | 33.89 | 0.9685 | |
| Scale | EDSR [ 71 ] | CRAN [ 72 ] | ELAN [ 43 ] | DAT [ 73 ] | SAFM [ 74 ] | MambaIR [ 20 ] | DBSD-Net | |
| 2 | PSNR | 41.83 | 42.14 | 46.88 | 42.74 | 45.18 | 46.31 | 48.86 |
| SSIM | 0.9887 | 0.9905 | 0.9956 | 0.9913 | 0.9933 | 0.9943 | 0.9959 | |
| 3 | PSNR | 36.36 | 37.42 | 38.80 | 37.72 | 39.59 | 39.02 | 39.66 |
| SSIM | 0.9757 | 0.9793 | 0.9869 | 0.9806 | 0.9865 | 0.9862 | 0.9896 | |
| 4 | PSNR | 34.84 | 35.11 | 35.28 | 33.15 | 35.66 | 35.87 | 36.08 |
| SSIM | 0.9566 | 0.9578 | 0.9679 | 0.9568 | 0.9669 | 0.9705 | 0.9731 |
| Scale | EDSR [ 71 ] | CRAN [ 72 ] | ELAN [ 43 ] | DAT [ 73 ] | SAFM [ 74 ] | MambaIR [ 20 ] | DBSD-Net | |
| 2 | PSNR | 49.36 | 48.37 | 51.57 | 51.13 | 50.20 | 52.42 | 54.05 |
| SSIM | 0.9911 | 0.9960 | 0.9971 | 0.9973 | 0.9942 | 0.9973 | 0.9982 | |
| 3 | PSNR | 45.46 | 46.22 | 49.87 | 48.97 | 48.42 | 48.56 | 50.66 |
| SSIM | 0.9941 | 0.9926 | 0.9958 | 0.9958 | 0.9934 | 0.9955 | 0.9967 | |
| 4 | PSNR | 42.99 | 44.21 | 46.79 | 46.06 | 45.11 | 47.46 | 47.92 |
| SSIM | 0.9721 | 0.9901 | 0.9921 | 0.9909 | 0.9875 | 0.9931 | 0.9937 |
| Region | Metric | EDSR [ 71 ] | CRAN [ 72 ] | ELAN [ 43 ] | DAT [ 73 ] | SAFM [ 74 ] | MambaIR [ 20 ] | DBSD-Net |
| EWP | Grad-MAE | 7.8649 | 7.6997 | 7.6383 | 7.6207 | 7.6137 | 7.6139 | 7.6095 |
| Grad-Corr | 0.5785 | 0.6033 | 0.6133 | 0.6190 | 0.6197 | 0.6205 | 0.6212 | |
| Front-F1 | 0.5588 | 0.5793 | 0.5818 | 0.5784 | 0.5798 | 0.5785 | 0.5794 | |
| FCD | 1.5558 | 1.5387 | 1.5526 | 1.5536 | 1.5408 | 1.5571 | 1.5555 | |
| AGM | Grad-MAE | 49.1438 | 48.4802 | 48.1875 | 47.9735 | 47.9740 | 47.9335 | 47.9028 |
| Grad-Corr | 0.6186 | 0.6410 | 0.6460 | 0.6511 | 0.6506 | 0.6524 | 0.6532 |
| Case | SSSM | DGM | VGGUNet++ | NIO | EWP | NP | AGM | ||||
| PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | PSNR | SSIM | ||||
| Case 1 | 43.21 | 0.9801 | 41.74 | 0.9846 | 36.27 | 0.9532 | 32.99 | 0.9470 | |||
| Case 2 | 42.97 | 0.9808 | 41.40 | 0.9833 | 36.16 | 0.9523 | 32.91 | 0.9453 | |||
| Case 3 | 42.78 | 0.9766 | 41.45 | 0.9813 | 35.92 | 0.9469 | 32.71 | 0.9372 | |||
| Case 4 | 43.53 | 0.9826 | 41.80 | 0.9853 | 36.39 | 0.9566 | 33.05 | 0.9490 | |||
| Case 5 | 43.53 | 0.9828 | 41.79 | 0.9854 | 36.41 | 0.9571 | 33.09 | 0.9497 | |||
Remote Sensing Image Super-Resolution
Remote sensing image super-resolution reconstructs fine spatial detail in satellite and aerial imagery from lower-resolution observations.
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