( ( Above ( the troposphere ) ) ( ( is ( ( ( an ( atmospheric ( ozone layer ) ) ) , ) ( which ( ( is also ) ( ( the ( lower layer ) ) ( of ( the stratosphere ) ) ) ) ) ) ) . ) )
(ROOT (SINV (PP (IN Above) (NP (DT the) (NNP troposphere))) (VP (VBZ is)) (NP (NP (DT an) (JJ atmospheric) (NN ozone) (NN layer)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADVP (RB also)) (NP (NP (DT the) (JJR lower) (NN layer)) (PP (IN of) (NP (DT the) (NN stratosphere)))))))) (. .)))
Above the troposphere is an atmospheric ozone layer, which is also the lower layer of the stratosphere .
(ROOT (S (NP (DT The) (NN stratosphere)) (VP (VBZ is) (NP (NP (DT the) (NN layer)) (PP (IN above) (NP (DT the) (NNP troposphere))))) (. .)))