When el niño occurs every three to seven years, a mass of warm pacific water that is usually pushed westward by trade winds group of answer choices surges back eastward toward south america. becomes much warmer than usual, strengthening trade winds. cools dramatically. sinks and therefore cools substantially. surges northward toward japan.

"When El Niño occurs every three to seven years, a mass of warm Pacific water that is usually pushed westward by trade winds, surges back eastward toward South America".

Explanation:

Under normal conditions, warm water and air masses move westward, which makes it possible for cold water to ascend in a process known as upwelling. This upwelling occurs in South America´s coasts, providing nutrients from the bottom to the animals, especially fishes -which favors fisheries activities-. Humidity goes straight to the west precipitating in Indochina and North Australia, among other places.

Under El Niño conditions, a tropical stream, that is normally small, acquires strength while the opposite streams debilitate. This avoids warm water to go westward, remaining in South America´s coasts, which produces unusual precipitations in Chile´s coasts -followed by floral bloom in Atacama desert-, and fewer precipitations in Eastsouth Asia and  North Australia. Upwelling does not occur, so there is a fishery crisis because nutrients from the bottom do no ascend and fish populations remain equal or smaller.    

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