( ( ( The ( mutual interaction ) ) ( between ( ( ( the ( upper ocean ) ) and ) ( the atmosphere ) ) ) ) ( ( was ( studied ( by ( ( ( ( Deser and ) Blackmon ) ( -LRB- ( 1993 -RRB- ) ) ) ( who ( showed ( that ( ( ( ( ( ( wintertime SSTs ) , ) ( sea ice ) ) and ) ( ( atmospheric fluctuations ) ( over ( the ( subpolar gyre ) ) ) ) ) ( ( change synchronously ) ( on ( decadal ( time scales ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ mutual) (NN interaction)) (PP (IN between) (NP (NP (DT the) (JJ upper) (NN ocean)) (CC and) (NP (DT the) (NN atmosphere))))) (VP (VBD was) (VP (VBN studied) (PP (IN by) (NP (NP (NNP Deser) (CC and) (NNP Blackmon)) (PRN (-LRB- -LRB-) (NP (CD 1993)) (-RRB- -RRB-)) (SBAR (WHNP (WP who)) (S (VP (VBD showed) (SBAR (IN that) (S (NP (NP (JJ wintertime) (NNS SSTs)) (, ,) (NP (NN sea) (NN ice)) (CC and) (NP (NP (JJ atmospheric) (NNS fluctuations)) (PP (IN over) (NP (DT the) (NN subpolar) (NN gyre))))) (VP (VBP change) (ADVP (RB synchronously)) (PP (IN on) (NP (JJ decadal) (NN time) (NNS scales))))))))))))) (. .)))
The mutual interaction between the upper ocean and the atmosphere was studied by Deser and Blackmon (1993) who showed that wintertime SSTs, sea  ice and atmospheric fluctuations over the subpolar gyre change synchronously on decadal time scales.
(ROOT (S (SBAR (WHADVP (WRB How)) (S (NP (NN ice) (NNS cores)) (VP (VBP are) (ADJP (JJ important) (PP (TO to) (NP (NP (DT the) (NN study)) (PP (IN of) (NP (JJ geologic) (NN history))))))))) (VP (VBZ is) (ADVP (RBS best)) (VP (VBN described) (SBAR (IN as) (S (NP (PRP they)) (VP (VBP contain) (NP (NN evidence) (NN showing) (NNS changes)) (PP (IN in) (NP (NP (DT the) (JJ atmospheric) (NN composition)) (PP (IN over) (NP (NN time)))))))))) (. .)))