( ( ( ( ( ( The ( suprathermal particles ) ) , ) ( ( electrons and ) protons ) ) , ) ( ( ( coming ( from ( the magnetosphere ) ) ) and ) ( precipitating ( into ( the ( high-latitude atmosphere ) ) ) ) ) ) ( ( are ( ( an ( energy source ) ) ( of ( ( the ( Earth 's ) ) ionosphere ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (DT The) (JJ suprathermal) (NNS particles)) (, ,) (NP (NNS electrons) (CC and) (NNS protons)) (, ,)) (VP (VP (VBG coming) (PP (IN from) (NP (DT the) (NN magnetosphere)))) (CC and) (VP (VBG precipitating) (PP (IN into) (NP (DT the) (JJ high-latitude) (NN atmosphere)))))) (VP (VBP are) (NP (NP (DT an) (NN energy) (NN source)) (PP (IN of) (NP (NP (DT the) (NN Earth) (POS 's)) (NN ionosphere))))) (. .)))
The suprathermal particles, electrons and protons, coming from the magnetosphere and precipitating into the high-latitude atmosphere are an energy source of the Earth's ionosphere.
(ROOT (S (NP (DT The) (NN atmosphere)) (VP (VBZ is) (NP (NP (DT the) (NN source)) (PP (IN of) (NP (NN precipitation))))) (. .)))