Ocean process taking different line before turning active (2,4)

I believe the answer is:
el nino
'ocean process' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'different line before turning active' is the wordplay.
'different' is an anagram indicator (letters placed in a different order).
'before' says to put letters next to each other.
'turning' is a reversal indicator.
'active' becomes 'on' (I've seen this in other clues).
'on' back-to-front is 'no'.
'line' with letters rearranged gives 'elni'.
'elni'+'no'='EL NINO'
'taking' acts as a link.
Can you help me to learn more?
(Other definitions for el nino that I've seen before include "Irregular Pacific climatic event" , "Pacific climate pattern" , "Climatic event affecting world's weather" , "Disrupter of weather patterns" , "Cause of weather change" .)
