Estimation of all-sky instantaneous photosynthetically active radiation from visible infrared imaging radiometer suite data using optimization method

Abstract

Surface incident photosynthetically active radiation (PAR) is an important input parameter for many ecosystem models and applications. We propose a method based on a radiative transfer model for estimating surface PAR from Visible Infrared Imaging Radiometer Suite (VIIRS) TOA observations by optimizing the surface and atmospheric variables with a cost function. Validation against measurements at seven Surface Radiation Budget Network (SURFRAD) sites resulted in an R2 of 0.92, a bias of 5.39 W/m2, and a root mean square error (RMSE) of 33.87 W/m2 (14.92%) for the instantaneous results. The validation at SURFRAD sites shows good accuracy. The algorithm is capable of generating radiation products at the spatial resolution of finer than 1 km.