What is the Walker Circulation?
The correct answer and explanation is :
The Walker Circulation refers to a large-scale atmospheric circulation pattern in the tropics, primarily in the Pacific Ocean. It is driven by the temperature differences between the eastern and western tropical Pacific and involves both oceanic and atmospheric components. The circulation plays a critical role in the distribution of heat, moisture, and winds across the tropical region.
Explanation:
The Walker Circulation is a key feature of tropical meteorology and is characterized by the movement of air and ocean currents across the equatorial Pacific. It begins in the western Pacific, where the sea surface temperatures are warmer and the air is more humid. The warm air rises in this region, creating a low-pressure zone. This rising air then moves eastward high in the atmosphere toward the central and eastern Pacific. As it moves, the air cools, and the moisture condenses, leading to cloud formation and rainfall, particularly over the central and eastern Pacific.
In the lower atmosphere, air flows from the eastern Pacific (where air pressure is higher due to cooler sea surface temperatures) toward the western Pacific to replace the rising warm air. This creates a large-scale, zonal (east-west) wind circulation that is most noticeable in the tropics.
At the surface, this circulation results in easterly trade winds (from east to west) across the equatorial Pacific, which are stronger in the central and western Pacific. In contrast, the eastern Pacific is generally characterized by lighter winds.
The Walker Circulation is tightly connected to the El Niño-Southern Oscillation (ENSO) phenomenon. During an El Niño event, the typical Walker Circulation weakens, and sometimes even reverses, leading to abnormal weather patterns like warmer-than-usual sea surface temperatures in the eastern Pacific, which can disrupt rainfall patterns and cause global climate impacts. Conversely, during a La Niña event, the Walker Circulation strengthens, leading to cooler sea surface temperatures and enhanced tropical convection in the western Pacific.
Overall, the Walker Circulation is crucial for the global climate system, influencing weather patterns, ocean currents, and temperature distributions across the equatorial Pacific.