The term "radiation flux" refers to the amount of radiation, or energy, that is being emitted or transmitted through a specific area or surface. It basically measures how much radiation is present in a particular location. Full definition
The internal kinetic energy is taken as the upward long wave energy flux at the top of the atmosphere, and the potential energy is the upward radiation flux from the surface. (friendsofscience.org)
They could then track both the net radiation flux and the temperature to estimate alpha in the traditional manner. (skepticalscience.com)
He especially enjoys research focused on the study of matter at extreme conditions of high pressure, high temperature, and high radiation flux. (unlv.edu)