That's why I need a chat about this. The TOTAL solar isolation at TOA is about 1380. And about 25% of that reaches the ground. I DONT BELIEVE that number is 24 hour averaged (like an ENERGY should be) because those numbers are W/sqm.. So if it's NOT time averaged --- we'd be an iceball with the RATES of 24 hour IR radiation, and the convection/conduction going skyward "MOST" of the day..
According to Trenberth the watts/sq m hitting the equator at high noon is about 1364. Since one side is in the dark that number is divided by 2.
Application of Lambert's law is used to account for the lower power outside the equatorial noon. That leads to another factor of 2.
So the total reduction in the equatorial noon power is a factor of 4 to provide a
daily average sunlight. 1364/4 = 341. That's where Trenberth gets his incoming solar radiation at the top center of his diagram.
In short the left side of Trenberth's diagram is already a daily time averaged W/sq m.
I hope this is not talking down to you, but your question is not too clear.
According to him the surface radiation minus the back radiation is 63 W. When you add that to the 17 W thermals and 80 W evaporation you get,
Power radiated from earth = 63+17+80 = 160 W.
If you compare that with the sun SW radiation from the sun, 161 W, you are missing 1 W in the power balance. That Watt is shown at the very bottom (0.9 W/sq m). Of course you can't subtract all those back of the envelope numbers and get anything meaningful. That 1 W is thrown in because that's what he considers leads to the global warming since 1890.