Final answer:
The phenomenon known as the El Niño Southern Oscillation (ENSO) includes the reversal of high and low pressure systems across the Pacific, with its cool phase La Niña and warm phase El Niño causing global weather changes.
Step-by-step explanation:
The reversal of the position of surface high and low pressure systems at opposite ends of the Pacific Ocean is called the El Niño Southern Oscillation (ENSO). The cool phase of ENSO, known as La Niña, is characterized by below-average Sea Surface Temperature (SST) in the eastern Pacific, with high air pressure in the eastern Pacific and low air pressure in the western Pacific. The warm phase, known as El Niño, involves a band of warm ocean water that develops in the central and east-central equatorial Pacific, leading to high air pressure in the western Pacific and low air pressure in the eastern Pacific. These switches between El Niño and La Niña cause significant global changes in temperatures and rainfall patterns.