Abstract
A new formula is proposed for estimation of net radiation based on the heat balance equation. All effects of various parameters to net radiation are involved in a non-dimensional parameter Rn+, which is derived through normalization with solar radiation and effective longwave radiation flux. Rn+is closely related to the temperature difference between the atmospher and the ground surface. This parameter Rn+on forest in the Tohoku district is calculated with actual climatic data sets. Through the discussion on sensitivity of Rn+to various parameters, it is shown that Rn+can be regarded as a constant under certain condition. Net radiation may be estimated from solar radiation, longwave radiation, air temperature and only one experimental constant Rn+.
