Advancing Our Understanding of Surface Water Temperature Dynamics in Transitional Environments through in Situ, Satellite, and Hydrodynamic Modeling.

Monitoring surface water temperature (SWT) in transitional environments remains challenging due to the interplay of natural and anthropogenic processes, which introduce greater complexity than in open-ocean systems. This study evaluates four SWT products for their ability to capture temperature dynamics in the Venice Lagoon, a well-monitored coastal system. The assessment included (1) output from the hydrodynamic model SHYFEM (System of Hydrodynamic Finite Element Module), (2) a satellite-based Level 4 product from the European Space Agency Climate Change Initiative (ESA CCI), (3) the Landsat 8 Level 2 standard thermal product, and (4) Landsat 8 Level 1 data processed using the Thermal Atmospheric Correction Tool (TACT). Validation against in situ observations indicated that SHYFEM and TACT showed lower bias (-0.48 °C and -0.30 °C, respectively) and RMSE (∼1.2 °C) than the other products. SHYFEM effectively reproduced intra-annual SWT trends with comprehensive temporal coverage, while TACT captured fine-scale spatial features, including thermal anomalies from industrial discharges. Building on this, an integrated product combining SHYFEM and TACT was developed, providing a more accurate and coherent representation of spatiotemporal SWT dynamics. This transferable framework advances understanding of thermal variability in transitional waters and has potential to support ecosystem management and climate adaptation strategies.