The impact of land cover generated by a dynamic vegetation model on climate over east Asia in present and possible future climate

摘要

This study investigates the impacts of land cover change, as simulated by adynamic vegetation model, on the summertime climatology over Asia. Theclimate model used in this study has systematic biases of underestimatedrainfall around Korea and overestimation over the South China Sea. Whencoupled to a dynamic vegetation model, the resulting change in land cover isaccompanied by an additional direct radiative effect over dust-producingregions. Both the change in land surface conditions directly and the effectof increased bare-soil fraction on dust loading affect the climate in theregion and are examined separately in this study. The direct radiativeeffect of the additional dust contributes to increasing the rainfall biases,while the land surface physical processes are related to local temperaturebiases such as warm biases over North China. In time slice runs for futureclimate, as the dust loading changes, anomalous anticyclonic flows aresimulated over South China Sea, resulting in reduced rainfall over the SouthChina Sea and more rainfall near Korea and south China. In contrast with therainfall changes, the influence of land cover change and the associated dustradiative effects are very small for a future projection of temperature, whichis dominated by atmospheric CO₂ increase. The results in this studysuggest that the land cover simulated by a dynamic vegetation model canaffect, and be affected by, model systematic biases on regional scales overdust emission source regions such as Asia. In particular, the analysis of theradiative effects of dust changes associated with land cover change isimportant in order to understand future changes in regional precipitation inglobal warming.