Which phenomenon describes irregular warming of the Pacific Ocean along with reversal of trade winds?

Which phenomenon describes irregular warming of the Pacific Ocean along with reversal of trade winds?

• A. La Niña
• B. Oscillation
• C. ENSO
• D. El Niño

Answer: (D)

El Niño describes a warming of the central and eastern Pacific Ocean that happens when the usual easterly trade winds weaken and can even reverse. This wind change reduces upwelling of cold water along the western coast of South America, so surface temperatures rise in the eastern Pacific and weather patterns shift globally. The combination of irregular warming and a reversal (weakening) of the trade winds is exactly what defines this phase, making it the best fit. The opposite phase, La Niña, involves cooler Pacific waters and stronger trade winds, not a reversal. ENSO is the overall cycle that includes both El Niño and La Niña, so it’s broader than the event described.

El Niño describes a warming of the central and eastern Pacific Ocean that happens when the usual easterly trade winds weaken and can even reverse. This wind change reduces upwelling of cold water along the western coast of South America, so surface temperatures rise in the eastern Pacific and weather patterns shift globally. The combination of irregular warming and a reversal (weakening) of the trade winds is exactly what defines this phase, making it the best fit. The opposite phase, La Niña, involves cooler Pacific waters and stronger trade winds, not a reversal. ENSO is the overall cycle that includes both El Niño and La Niña, so it’s broader than the event described.