( ( Ocean ( ( ( ( ( currents , ) ( if cold ) ) , ) and ) ( clinging ( to ( the bottom ) ) ) ) ) . )
(ROOT (NP (NP (NNP Ocean)) (VP (VP (VBG currents) (, ,) (SBAR (IN if) (FRAG (ADJP (JJ cold))))) (, ,) (CC and) (VP (VBG clinging) (PP (TO to) (NP (DT the) (NN bottom))))) (. .)))
Ocean currents, if cold, and clinging to the bottom.
(ROOT (S (NP (JJ Deep) (NNS currents)) (VP (VBP are) (VP (VBN caused) (PP (IN by) (NP (NP (NNS differences)) (PP (IN in) (NP (NN density))))) (PP (IN at) (NP (NP (DT the) (NN top) (CC and) (NN bottom)) (PP (IN of) (NP (DT the) (NN ocean))))))) (. .)))