Future increase in the all-sky UV-B radiation over asia projected by an earth system model

Direct simulations of the surface all-sky uv-b radiation in an earth system model (miroc-esm-chem) are validated against the operational ground-based measurements of spectral uv radiation at sapporo,tateno,kagoshima,naha,and chengkung. the model reasonably reproduces the mean seasonal evolution of the surface uv-b radiation at sapporo and naha,but substantially overestimates it at tateno and kagoshima during the summer. underestimation of the cloud e{currency sign}ect at these two sites contributes to the overestimation. a projection of the seasonal evolution of the monthly mean uv-b radiation into the future shows a general increase in the 2090s compared to the 2000s. while a slight reduction of the column ozone contributes to the uv-b increase,the e{currency sign}ects of the reduction in cloud forcing and,especially,of the reduction in aerosols contribute more significantly. the month for which the largest increase in the uv-b radiation is projected varies site-by-site,reflecting local changes in forcing due to aerosols and clouds. © 2012,meteorological society of japan.