Satellite observation reveals wetland-induced local cooling moderated by regional climate gradients

Wetlands influence local land surface temperature (LST) via biogeophysical processes, nevertheless, their temperature regulation under different moisture conditions remain unclear. This study quantified the spatial heterogeneity and drivers of wetland-induced temperature effects in the Amur River Basin using multi-year averaged LST data (2003–2022) within a space for time paired comparison framework. Our findings demonstrate that LST regulation of wetlands showed distinct diurnal asymmetry. During the growing season (May–September), natural wetlands induce substantial daytime cooling (−1.20 ± 0.77 K) and slight nighttime warming (0.05 ± 0.63 K). Artificial paddy wetlands show similar patterns but stronger nighttime warming (0.64 ± 0.41 K), reducing net cooling. Both wetland types absorb more solar radiation than adjacent drylands (natural: −0.67 % ± 0.88 %; artificial: −0.60 % ± 0.65 %) and dissipate energy primarily through enhanced evapotranspiration in early growing season (May–July) (0.13 ± 0.30 mm/d; 0.02 ± 0.22 mm/d). Nighttime heat release from water and soil partially offsets daytime cooling. Natural wetlands maintain superior cooling via stable non-radiative processes, with synchronized nighttime cooling in humid regions and compensatory nighttime warming in arid regions, ensuring consistent temperature reduction across hydrological gradients. Conversely, artificial paddy fields in semi-arid areas achieve strong cooling (−0.82 ± 0.34 K) through dual-phase evapotranspiration (0.128 ± 0.263 mm/d; 0.003 ± 0.236 mm/d). In humid regions, nighttime heat storage and release exceed daytime cooling, causing marginal warming. Thus, the cooling effect of artificial paddy fields is governed by moisture, evapotranspiration, and inundation. These results highlight that the artificial paddies cannot fully replace natural wetlands in climate regulation, underscoring the need to prioritize natural wetland conservation and restoration in land-use and climate strategies. • Wetlands exhibit asymmetric cooling effects, mainly occurring during the daytime. • Paddy fields cool more effectively in semi-arid regions than in humid regions. • Non-radiative processes control wetland cooling and shape its variability. • Natural wetland cooling effects cannot be replicated by artificial restoration.