Simulating Nighttime Visible Satellite Imagery of Tropical Cyclones Using Conditional Generative Adversarial Networks

Visible (VIS) imagery of satellites has various important applications in meteorology, including monitoring Tropical Cyclones (TCs). However, it is unavailable at night because of the lack of sunlight. This study presents a Conditional Generative Adversarial Networks (CGAN) model that generates highly accurate nighttime visible reflectance using infrared (IR) bands and sunlight direction parameters as input. The model was trained and validated using target area observations of the Advanced Himawari Imager (AHI) in the daytime. This study also presents the first nighttime model validation using the Day/Night Band (DNB) of the Visible/Infrared Imager Radiometer Suite (VIIRS). The daytime statistical results of the Structural Similarity Index Measure (SSIM), Peak Signal-to-Noise Ratio (PSNR), Root Mean Square Error (RMSE), Correlation Coefficient (CC), and Bias are 0.885, 28.3, 0.0428, 0.984, and -0.0016 respectively, completely surpassing the model performance of previous studies. The nighttime statistical results of SSIM, PSNR, RMSE, and CC are 0.821, 24.4, 0.0643, and 0.969 respectively, which are slightly negatively impacted by the parallax between satellites. We performed full-disk model validation which proves our model could also be readily applied in the tropical ocean without TCs in the northern hemisphere. This model contributes to the nighttime monitoring of meteorological phenomena by providing accurate AI-generated visible imagery with adjustable virtual sunlight directions.