Which mechanism reduces streamflow during El Niño events in the Amazon basin?

💡 Explanation

During El Niño, the Walker circulation weakens because the pressure gradient across the Pacific Ocean reduces, leading to less moisture transport to the Amazon and decreased rainfall, impacting streamflow. Therefore, a weakened Walker circulation results, rather than changes in trade winds, orographic lift or glacial melt which are not primary El Niño effects in Amazonia.

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