Answer and Explanation:
The ENSO phenomenon is the result of a complex system of climatic oscillations between the ocean and the atmosphere. It is considered to be dominant in the global climate system. This phenomenon is associated with important perturbations in the normal pluvial regimens in the tropics, resulting in dry seasons in areas where usually rains, and rainy seasons in areas that are usually desertic.
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, which is normally small, acquires strength while the opposite streams debilitate. This avoids warm water to go eastward, remaining in South America´s coasts, which produces unusual precipitations in areas such as Chile´s coasts -followed by floral bloom in Atacama desert-, and fewer precipitations in Eastsouth Asia and North Australia. Upwelling does not occur on the coasts of South America, so there is a fishery crisis because nutrients from the bottom do no ascend and fish populations remain equal or smaller. In areas such as Piura, Perú, during el Niño events, temperatures use to rise in the coastal areas and precipitation also increase. Nueva Guinea, on the other hand, seems to one of the most affected areas in Eastsouth Asia under the influence of El Niño event. Rainfall during ENSO drops below the average, affecting crops and livestock.
ENSO also provokes changes in general extratropical circulation contributing to some anomalous situation in the northern hemisphere weather during winter, including severe precipitations and cooler temperatures in the southeast USA, north of Mexico, Gulf of Mexico, Strait of Florida and western Cuba.
