Estimation of instantaneous and daily net radiation from MODIS data under clear sky conditions: a case study in East Asia

The Moderate Resolution Imaging Spectroradiometer-based net radiation ( R N ) model was built and applied in East Asia in 2005. Because there have hardly been simple parameterization schemes developed over a large area using remote-sensing technology, the model was aimed to present physical simplicity in complex topography at multiple spatiotemporal scales. The model successfully reproduced the instantaneous R N values obtained at four flux tower sites having individually different ecohydrology. The diurnal cycle of R N was contextually simulated using a simple sine curve to determine the daily and monthly average net radiation. The diurnal R N estimation method was proven to be a reliable model as long as accurate boundary conditions, sunrise and sunset times, for example, were obtained. The monthly average net radiation (MANR) was estimated using the diurnal patterns of the instantaneous R N . Distribution of the monthly R N demonstrated that elevation and latitude were the primary factors affecting the MANR. The proposed R N algorithm turned out to be a promising method for valuable applications in various fields due to systematic simplicity and fewer input parameters.