A Novel Way to Calculate Shortwave Black Carbon Direct Radiative Forcing

This study proposes a multiband synthetic method to calculate the BC DRF. It is compared with the empirical formula method and broadband method. The multiband synthetic method inputs the 6 narrowband black sky albedo of MODIS and other data into the 6S model to calculate the sky scattered light ratio of each narrowband and obtains the narrowband blue sky albedo. And input the BC AOD and the synthesized broadband shortwave blue sky albedo into the 6S model to obtain the shortwave BC DRF. This study found that the BC DRF calculated by the three methods at the TOA is significantly different, while the difference between the three methods at the SFC is small. The values of BC DRF calculated by these three methods are multiband synthetic method, broadband method, and empirical formula method from high to low. Therefore, when calculating shortwave BC DRF, the difference in atmospheric scattering effects on narrow bands should be considered.