Solar radiation absorption due to water vapor: Advanced broadband parameterizations

Accurate parameterizations for calculating solar radiation absorption in th e atmospheric column due to water vapor lines and continuum are proposed fo r use in broadband shortwave radiative transfer codes. The error in the abs orption values is less than 1.5 W m(-2) as compared with the values obtaine d by the line-by-line method for the three standard atmospheres and solar z enith angles of 30 degrees and 75 degrees. The error in the heating rates i s less than 0.1 K day(-1) at most of the atmospheric levers. The additional absorption of solar radiation due to the water vapor continu um was also estimated. Its magnitude in the total near-infrared region of t he solar spectrum is noticeable and reaches 13.0 W m(-2) (6.4% from the wat er vapor absorption in lines) for the tropical atmosphere and solar zenith angle of 30 degrees. Therefore, using of the proposed parameterizations can help to obtain better agreements between the solar radiative fluxes calcul ated and measured at the earth's surface.