Solar radiation enters the Earth's atmosphere with a portion being scattered by clouds and aerosols.

Processing, archiving and distributing Earth science data
at the NASA Langley Research Center

What is Flux?

Flux - is an energy flow through a unit area over a unit time; hence the units of W m-2. As radiation interacts with matter at all atmospheric layers and surfaces, measuring, understanding, and modeling the spatial, temporal and spectral distribution of fluxes is important. Flux characterizes our climate and is represented as Up, Down, Net, TOA & Surface.