Impact of Forests on Local Temperature Based on Satellite Observations

Abstract:

Much of current knowledge on the biophysical effect of forests on climate comes from large-scale vegetation clearing experiments in climate models. However, due to uncertainties and coarse spatial resolution, models are unable to provide reliable information on local climate effect. Evidence on local temperature effects of forests from field observations is limited within a small spatial range, which is insufficient to address global forests with high heterogeneity. In this study, we present new evidence acquired from satellite observations to investigate how forest affects local temperature through biophysical mechanisms from a global perspective. Results show tropical forest has strong cooling effect throughout the year. Northern/southern temperate forests have weak/moderate cooling, peak in summer but weak in winter. Boreal forest has significant warming effect in particularly in winter. A diurnal asymmetric feature is observed at most forests, which is daytime cooling and nighttime warming relative to open land. The spatiotemporal patterns are largely a consequence of the competing effects of albedo and evapotranspiration, which also depend on climate conditions especially humidity and snow. Our study reveals biophysical mechanisms have consistent impact on local climate in terms of temperature with those large-scale impacts from climate models. This information could be used to inform forest management at local level and possible climate effects of the ongoing land use activities of forestry.