A comparison of modeled and measured surface shortwave irradiance for a molecular atmosphere

We compare the downward diffuse and direct normal irradiance computed by a two-stream model with measurements taken at the Mauna Loa Observatory when the atmosphere was close to a molecular atmosphere. The modeled downward di ffuse irradiance agrees with measurements taken by a shaded pyranometer wit hin the uncertainty of the measurement. Therefore, the two-stream approxima tion is adequate for computing the downward diffuse irradiance in a molecul ar atmosphere. This result also indicates that neglecting the state of pola rization introduces a negligible error in the irradiance computation. Publi shed by Elsevier Science Ltd.