The El Niño-Southern Oscillation
A)occurs every year around Christmas time in the southern Pacific Ocean.
B)is a periodic shift of high and low pressure zones over the western and eastern Pacific,respectively,usually occurring every 2 to 12 years.
C)is a pattern of sea surface,air pressure,and wind shifts between the northern and tropical western Pacific.
D)is a north-south fluctuation of high and low pressure zones in the North Atlantic Ocean.
E)has weakened throughout the 20th Century and is expected to disappear completely in the first couple of decades of the 21st century.

Question

Quizplus · Accepted Answer

The El Niño-Southern Oscillation is a periodic shift of high and low pressure zones over the western and eastern Pacific, typically occurring every 2 to 12 years. It is not an annual occurrence nor is it a pattern of sea surface, air pressure, and wind shifts between the northern and tropical western Pacific as described in choices A and C. It also does not occur in the North Atlantic Ocean as described in choice D. Finally, while there is debate about the future intensity and frequency of El Niño events, there is no current consensus that they will disappear completely in the first couple of decades of the 21st century, making choice E incorrect.