 Solution

The profile shows a low-ozone mixed layer up to approximately 2 km, with roughly 30 ppb ozone, and an overlying free-tropospheric value of roughly 50 ppb. The rise occurs through a transition layer extending to about 2.8 km, so these are approximate regime readings, not exact values for every altitude. The horizontal axis is already a mixing ratio; it does not provide a number density without additional air-density information.