🤖 AI Summary
Accurately simulating global oceanic phytoplankton biomass is hindered by inadequate parameterizations, sparse observations, and the inherent complexity of underlying biogeochemical processes. This work proposes a deep learning–based modeling framework that integrates satellite-derived observations with physical environmental variables through both static and autoregressive UNet architectures to effectively capture seasonal to interannual variability in phytoplankton dynamics. Experimental results demonstrate that the UNet outperforms benchmark models—including CNN, ConvLSTM, and 4CastNet—in reconstructing the spatiotemporal distribution of phytoplankton biomass. Moreover, its autoregressive variant enables high-accuracy short-term forecasts up to five months ahead, substantially enhancing the capability to simulate dynamic changes in marine ecosystems.
📝 Abstract
Phytoplankton is the basis of marine food webs, driving both ecological processes and global biogeochemical cycles. Despite their ecological and climatic significance, accurately simulating phytoplankton dynamics remains a major challenge for biogeochemical numerical models due to limited parameterizations, sparse observational data, and the complexity of oceanic processes. Here, we explore how deep learning models can be used to address these limitations predicting the spatio-temporal distribution of phytoplankton biomass in the global ocean based on satellite observations and environmental conditions. First, we investigate several deep learning architectures. Among the tested models, the UNet architecture stands out for its ability to reproduce the seasonal and interannual patterns of phytoplankton biomass more accurately than other models like CNNs, ConvLSTM, and 4CastNet. When using one to two months of environmental data as input, UNet performs better, although it tends to underestimate the amplitude of low-frequency changes in phytoplankton biomass. Thus, to improve predictions over time, an auto-regressive version of UNet was also tested, where the model uses its own previous predictions to forecast future conditions. This approach works well for short-term forecasts (up to five months), though its performance decreases for longer time scales. Overall, our study shows that combining ocean physical predictors with deep learning allows for reconstruction and short-term prediction of phytoplankton dynamics. These models could become powerful tools for monitoring ocean health and supporting marine ecosystem management, especially in the context of climate change.