Toward Accurate, Efficient, and Consistent Global Flux Simulations

Clouds modulate radiative energy budget of the earth-atmosphere system. To investigate the influence of clouds on the global energy budget, we simulate radiative fluxes using the Moderate Resolution Imaging Spectrometer (MODIS) cloud retrieval products. Because a significant amount of measurements are contained in the products and rigorous radiative transfer is computationally expensive, tremendous amount of computational resources are required to do simulations on the global scale. Therefore, several optimal methods for the flux calculations have to be evaluated before the simulations are carried out. The Rapid Radiative Transfer Model (RRTM) with implementation of several radiative solvers is used to simulate radiative fluxes in the shortwave and longwave spectral regions when clouds are present. The MODIS Collection 6 cloud models are utilized to ensure that the optical properties of clouds are consistent in the MODIS cloud products and flux simulations. In the sensitivity test, an accurate and efficient way is selected to calculate fluxes. Furthermore, the fluxes simulated by the method are evaluated against measurements from the Clouds and the Earth’s Radiant Energy System (CERES) and the Baseline Surface Radiation Network (BSRN) sites.