Shortwave radiative fluxes from MODIS: Model development and implementation

Abstract

A forward inference scheme driven with satellite-based information is developed to derive top of the atmosphere, surface, and atmospheric spectral shortwave radiative fluxes at global scale. The model takes into account all major atmospheric constituents, the characteristics of water and ice clouds, and the variation of cloud particle effective radius. The multilayered structure accounts for surface elevation effects and for the vertical distribution of the radiative fluxes. Spectral fluxes such as photosynthetically active radiation and near-infrared radiation can also be estimated. The model is implemented with products from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor both on Terra and Aqua at 1° spatial resolution for a 3-year period (2003-2005) and at global scale. The derived surface fluxes are evaluated against the globally distributed Baseline Surface Radiation Network (BSRN) measurements and compared with products from independent sources. It is demonstrated that the twice a day MODIS-based estimates of daily radiative fluxes adjusted for the diurnal cycle and the ground observations have a correlation coefficient greater than 0.96, a relative root-mean-square error less than 18%, and a relative bias between 0 and 6% for BSRN sites located in the Antarctic, the Atlantic (islands), North America, Europe, and other continental sites. Copyright 2009 by the American Geophysical Union.