The effect of three-dimensional radiative heat transfer in cloud fields using the radiation element method

The effects of three-dimensional (3D) radiative heat transfer in cloud fields are investigated by using the radiation element method by ray emission model (REM2). We have performed a 3D radiative heat transfer simulation in two fair-weather cumuli that are subjected to solar and sky irradiation. One of the features in this simulation is that both shortwave radiation and longwave radiation are considered. As a result, the effect of shortwave radiation is not so substantial as compared with that of longwave radiation in terms of the heat generation rate within the cloud. Also, the radiative interaction does not strongly affect the relative differences of the average heat generation rate between the single cloud model and the double cloud model. However, the distributions of heat generation rate at the thin layer beneath the cloud surface are influenced by radiative interaction and shadowing effect. Hence, these effects caused by 3D radiative heat transfer are important for horizontal inhomogeneous cloud fields.