Understanding El Niño Impacts

El Niño is a climate pattern characterized by unusually warm ocean temperatures in the central and eastern tropical Pacific Ocean.

Key events associated with El Niño include:

• Weakening of Trade Winds: The normal east-to-west blowing trade winds across the Pacific weaken or even reverse direction.
• Ocean Warming: The weakening winds allow warmer surface waters to move eastward from the western Pacific towards the coast of South America.
• Reduced Upwelling: Along the coast of Peru and Ecuador, the weakening offshore winds reduce the process of upwelling, where cold, nutrient-rich deep ocean water rises to the surface. This reduction significantly impacts marine ecosystems.
• Altered Weather Patterns: El Niño affects global weather, often causing drought in some regions (like Australia and parts of Asia) and increased rainfall in others (like the southern US). It typically leads to less monsoon rainfall in India.

Analyzing the Options

Based on the characteristics of El Niño:

• Option 1 (Stronger Trade Winds): Incorrect. El Niño is defined by the weakening of trade winds.
• Option 2 (Warmer SST in Western Pacific): Incorrect. While the western Pacific influences El Niño, the defining characteristic is the warming of the *central and eastern* tropical Pacific.
• Option 3 (Reduced upwelling along Peru coast): Correct. This is a direct consequence of the weakened trade winds and altered ocean currents during El Niño.
• Option 4 (More monsoon rainfall in India): Incorrect. El Niño events are generally associated with a weaker monsoon and potentially less rainfall in India.

Therefore, the occurrence during El Niño among the given options is the reduced upwelling along the Peru coast.