Solution
= Solution
The profile shows a low-ozone mixed layer up to approximately \b[2 km], with roughly \b[30 ppb <ozone>], and an overlying free-tropospheric value of roughly \b[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.