Asymmetrical cooling effects of Amazonian protected areas across spatiotemporal scales

Amazonian protected areas (PAs) play an important role in maintaining the regional and global ecosystem services, biodiversity and climate change mitigation. The effects of Amazonian PAs on climate change mitigation mainly focus on the carbon sequestration benefits. The biophysical effects of PAs on regulating the local energy budgets, and hence changing local climate, however, are often ignored. Using multiple satellite observation datasets, we evaluated the effects of Amazonian PAs on land surface temperature (LST) and the biophysical mechanisms of PAs on surface albedo and evapotranspiration (ET). We showed that Amazonian PAs have a cooling effect on local LST in relative to nearby croplands and non-protected areas (non-PAs) with the same land cover as PAs. The asymmetrical cooling effects of Amazonian PAs between daytime and nighttime, and between the dry and wet seasons sustain lower diurnal and seasonal temperature ranges, respectively, than non-PAs and croplands. The protected forests have stronger cooling effects, and more effectively moderate the diurnal and seasonal temperature ranges than the protected savannas due to the higher effects on surface albedo and ET. The non-PAs show weaker cooling effect than PAs, indicating reduced thermal buffering effect in non-PAs. Our results highlighted the great potential of natural vegetation in PAs versus non-PAs and croplands in buffering local thermal environment and the necessity of natural vegetation conservation in Amazon region.