A global view of one‐dimensional solar radiative transfer through oceanic water clouds

Abstract

Solar radiative transfer through a cloudy atmosphere is commonly computed assuming clouds to be one‐dimensional, i.e., plane‐parallel. Here we provide a global perspective on how often and with what degree oceanic water clouds may be considered plane‐parallel by fusing multi‐view‐angle and multi‐spectral satellite data. We show that the view‐angular distribution of the retrieved reflectance, spherical albedo and cloud optical thickness measured at 1 km resolution are indistinguishable from plane‐parallel clouds 24%, 25% and 79% of the time, respectively, at the 95% confidence level of our measurement method. These plane‐parallel clouds occur most frequently within regions dominated by stratiform clouds under solar zenith angles <60°. For all other regions or sun‐angles, the frequency in which clouds are indistinguishable from plane‐parallel drops sharply to as low as a few percent. Our results provide a basis for interpreting space‐time variability within many satellite‐retrieved variables and reveal a need for continued efforts to handle three‐dimensional radiative transfer in environmental modeling and monitoring systems.