( ( The ( dynamo ( current system ) ) ) ( substantially ( ( ( alters ( the ( ionospheric response ) ) ) ( to ( ( gravity wave ) ( ( forcing ( both ( ( parallel and ) perpendicular ) ) ) ( to ( ( the ( Earth 's ) ) ( magnetic field ) ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (DT The) (NN dynamo) (JJ current) (NN system)) (ADVP (RB substantially)) (VP (VBZ alters) (NP (DT the) (JJ ionospheric) (NN response)) (PP (TO to) (NP (NP (NN gravity) (NN wave)) (VP (VBG forcing) (NP (DT both) (NN parallel) (CC and) (NN perpendicular)) (PP (TO to) (NP (NP (DT the) (NN Earth) (POS 's)) (JJ magnetic) (NN field))))))) (. .)))
The dynamo current system substantially alters the ionospheric response to gravity wave forcing both parallel and perpendicular to the Earth's magnetic field.
(ROOT (S (NP (NNP Gravity) (CC and) (NNP magnetism)) (VP (VBP are) (NP (DT both) (JJ common) (NNS forces))) (. .)))
Gravity and magnetism are both common forces.