WGAST: Weakly-Supervised Generative Network for Daily 10 m Land Surface
  Temperature Estimation via Spatio-Temporal Fusion
Authors: name: Sofiane Bouaziz, name: Adel Hafiane, name: Raphael Canals, name: Rachid Nedjai

Urbanization, climate change, and agricultural stress are increasing the
demand for precise and timely environmental monitoring. Land Surface
Temperature (LST) is a key variable in this context and is retrieved from
remote sensing satellites. However, these systems face a trade-off between
spatial and temporal resolution. While spatio-temporal fusion methods offer
promising solutions, few have addressed the estimation of daily LST at 10 m
resolution. In this study, we present WGAST, a Weakly-Supervised Generative
Network for Daily 10 m LST Estimation via Spatio-Temporal Fusion of Terra
MODIS, Landsat 8, and Sentinel-2. WGAST is the first end-to-end deep learning
framework designed for this task. It adopts a conditional generative
adversarial architecture, with a generator composed of four stages: feature
extraction, fusion, LST reconstruction, and noise suppression. The first stage
employs a set of encoders to extract multi-level latent representations from
the inputs, which are then fused in the second stage using cosine similarity,
normalization, and temporal attention mechanisms. The third stage decodes the
fused features into high-resolution LST, followed by a Gaussian filter to
suppress high-frequency noise. Training follows a weakly supervised strategy
based on physical averaging principles and reinforced by a PatchGAN
discriminator. Experiments demonstrate that WGAST outperforms existing methods
in both quantitative and qualitative evaluations. Compared to the
best-performing baseline, on average, WGAST reduces RMSE by 17.18% and improves
SSIM by 11.00%. Furthermore, WGAST is robust to cloud-induced LST and
effectively captures fine-scale thermal patterns, as validated against 33
ground-based sensors. The code is available at
https://github.com/Sofianebouaziz1/WGAST.git.