A Question on the Model Output in Integration Loop

[FuchengY]

I am new to CESM (CAM) and have a question after reading the model's documents and codes. As I understand it, within each time step the model state is advanced sequentially through dynamics, adjustment physics, radiation, and coupling. The atmospheric state is written to the history files between the adjustment physics and radiation steps, a convention that dates back to CCM2. I am curious whether there is a specific physical or practical rationale for outputting the model state at this particular stage of the time step. In addition, given that the ultimate goal of the model is to predict the real weather/climate system, how should one interpret the comparability of this intermediate model state with observations?