The unresolved energy-unclosed problem in micrometeorology refers to the fact that the sum of turbulent fluxes (sensible and latent heat fluxes, Hs and LE) monitored by eddy covariance (EC) methods tends to be lower than the available energy (net radiation (Rn), soil heat flux (G), and heat storage (S)). The lack of energy balance closure (EBC) increases evapotranspiration-measurement uncertainty. Using EC data from Xishuangbanna, a Southeast Asian tropical seasonal rainforest, we analyzed the energy distribution and closure based on micrometeorological features. We found that: (1) the EBC in the rainy season exceeds that in other seasons and that the seasonal moisture content, frictional wind velocity (u*), and LE contribute to the high seasonal variability in EBC; (2) the annual closure is approximately 65%, and energy non-closure is influenced by turbulence intensity and atmospheric stability. When the atmospheric state is unstable to near neutral, u* is greatest, and EBC can reach nearly 80%. (3) energy is mainly allocated to LE, and energy non-closure leads to LE underestimation, especially in the foggy-cool and hot-dry seasons. (4) Heat storage and large time-scale flux effects on EBC were excluded. The causes of energy non-closure in the tropical calm zone need further investigation.

Introduction: Obtaining wetland data with high spatial accuracy and typological completeness is essential for understanding ecosystem functions, evaluating services, and informing conservation policy. However, fine-scale wetland mapping in tropical island regions remains challenging due to persistent cloud cover, image limitations, complex wetland types, and dynamic hydrology.Methods: We developed a sub-meter resolution wetland mapping framework for Hainan Island, China, by integrating multi-source optical imagery (WorldView-2/3, Gaofen-1/2), dual-temporal features, and RTK-based field validation. A hierarchical classification system was designed, consisting of three major categories and 17 subcategories, aligned with Ramsar Convention criteria and adapted to island-specific conditions.Results: The 2019 wetland map (3842.84 km²) achieved an overall accuracy of 96.13% (Kappa = 0.95). The framework successfully identified numerous small and fragmented wetland patches (0.0004–0.08 km²) that had been omitted in national wetland inventories. The results also revealed rapid artificial wetland expansion and pronounced spatial heterogeneity in natural wetlands.Discussion: This study delivers a reliable high-resolution dataset and a replicable methodology for tropical island wetland mapping. The results provide a critical basis for wetland monitoring, blue carbon assessment, and ecological management, while offering a transferable framework that can be applied to other coastal and island environments.