Emphasizing the land use-cloud-radiation feedback in detecting climate effects of land use and land cover changes

Previous assessments on climate effects of land use and land cover changes (LUCC) mostly focused on the altered surface upward shortwave radiation flux due to changes in surface albedo. However, the explorer on the physical mechanism using the Weather Research and Forecasting model with subgrid scale process precisely described here revealed that the LUCC impacts could not be directly interpreted by surface albedo changes only. The land use-cloud-radiation feedback, within which cloud amount and cloud ceiling, large-scale circulation related moisture flux and local evaporation were altered, played an essential role in affecting surface energy and water budgets between land surface and the atmosphere, especially for the impacted downward shortwave radiation flux. With subgrid scale process considered in describing LUCC and the land use-cloud-radiation feedback emphasized, LUCC impacts on surface air temperature (SAT), precipitation and near-surface wind speed (NSWS) were explored, which displayed marked temporal and spatial characteristics. The LUCC climate effects for both the influenced terrestrial subregions and the intensity were larger over summertime, expressing marked affection on the East Asian Summer Monsoon system. The LUCC impacts on SAT and NSWS mainly presented as changes in mean state, whereas the influences on the precipitation principally displayed as changes in the variability. LUCC induced changes in the averaged SAT, precipitation and NSWS were small, whereas the nearly symmetric distributions between positive and negative changes, which contributed to total changes, were much larger and might have a considerable impact on local and regional climate, especially on extreme climate events.