What hot spot? There is none to date.Ian, what do you believe causes the tropical hotspot?
Ian believes that they have been looking for the tropospheric hot spot in the wrong place... Rather than finding the hot spot at 6 to 14 km in altitude as the greenhouse theory predicts...Ian thinks the hot spot is actually mere millimeters off the ground.
I was one of the first here to point out and criticize the models predictions for the hot spot. And the misdirection by RealClimate who used changing scales and colours in their graphs (where your first graph originated). The hotspot is a water and convection process, obviously incorrectly modeled.
You are correct in pointing out that I believe the CO2 bottleneck is in the first ten metres from the surface. The atmosphere is warmed by the Sun, and by the surface. CO2 is the simplest to understand. All CO2 specific surface radiation is absorbed to extinction in the first ten metres. Adding or subtracting CO2 just changes the ten metre number down or up slightly. All that energy is absorbed very close to the surface and the atmosphere is warmed by thermalization when molecules collide and spread the energy around into different forms.
This is an important point! CO2 which is 100 metres up is not being excited by direct surface radiation. Not at 1000 metres or 10,000 metres either, it is all absorbed in the first 10 metres. A bottleneck, or as you put it, a hotspot.