( ( ( 4.2 Understanding ) ( of ( the ( Middle ( Atmosphere ( Thermosphere-Ionosphere ( Coupling System ) ) ) ) ) ) ) ( 4.2 . ) )
(ROOT (S (NP (NP (CD 4.2) (NN Understanding)) (PP (IN of) (NP (DT the) (NNP Middle) (NNP Atmosphere) (NNP Thermosphere-Ionosphere) (NNP Coupling) (NNP System)))) (VP (VBZ 4.2)) (. .)))
4.2 Understanding of the Middle Atmosphere Thermosphere-Ionosphere Coupling System 4.2.
(ROOT (S (NP (NNP Thermosphere)) (VP (VBZ is) (NP (DT the) (JJ upper-most) (NN atmosphere))) (. .)))