Spatio-temporal changes in the high and low-pressure systems in the tropical eastern and western Pacific Ocean are called as:

Correct option is C

The Southern Oscillation refers to the irregular pattern of changing air pressure between the eastern and western tropical Pacific Ocean. It is a key component of the El Niño-Southern Oscillation (ENSO) phenomenon.
Key Explanation:
1. Southern Oscillation Index (SOI):
· Measures differences in air pressure between Tahiti (eastern Pacific) and Darwin, Australia (western Pacific).
· A negative SOI indicates El Niño conditions (low pressure in the east, high pressure in the west).
· A positive SOI indicates La Niña conditions (high pressure in the east, low pressure in the west).
2. Walker Circulation:
· Refers to the zonal (east-west) atmospheric circulation over the tropical Pacific, driven by pressure differences.
· Changes in the Walker Circulation are linked to the Southern Oscillation but are distinct phenomena.
Why Not Other Options?
· Walker Oscillation (a): This term is not commonly used to describe pressure changes.
· Walker Circulation (b): Refers to the atmospheric circulation, not the pressure system changes.
· Ferrel Oscillation (d): Refers to mid-latitude atmospheric circulation patterns, unrelated to the Pacific Ocean.
Thus, the correct answer is (c) Southern Oscillation.
Information Booster: 1. El Niño-Southern Oscillation (ENSO):
· Comprises El Niño (warming in the eastern Pacific) and La Niña (cooling in the eastern Pacific) events.
· ENSO significantly impacts global weather patterns, including monsoons, droughts, and floods.
2. Southern Oscillation Index (SOI):
· Positive SOI → Strong trade winds → La Niña.
· Negative SOI → Weakened trade winds → El Niño.
3. Walker Circulation:
· The east-west atmospheric circulation over the tropical Pacific, influenced by the Southern Oscillation.
Additional Knowledge: (a) Walker Oscillation:
· Incorrect term; likely a misnomer for Southern Oscillation or Walker Circulation.
(b) Walker Circulation:
· East-west atmospheric movement over the Pacific but does not directly describe pressure differences.
(c) Southern Oscillation:
· Describes pressure variations between the eastern and western tropical Pacific.
(d) Ferrel Oscillation:
· Related to mid-latitude circulations, not tropical Pacific systems.