what is the walker circulation of normal & El nino conditions? help me
The Walker circulation refers to the atmospheric circulation over the tropical Pacific Ocean, particularly between the western and eastern parts. It influences long-term weather patterns and is closely linked to the El Niño-Southern Oscillation (ENSO) phenomenon. The Walker circulation has two primary phases: normal and El Niño conditions.
During normal conditions, the Walker circulation is characterized by a large-scale tropical atmospheric circulation pattern. Warm, moist air from the western Pacific rises near Indonesia, creating an area of low pressure. This causes winds to blow from east to west across the equatorial Pacific, and the trade winds are strong and consistent. As the air moves westward, it descends and creates a region of high pressure over the eastern Pacific, near the coast of South America.
During El Niño conditions, the Walker circulation weakens or even reverses. Warm sea surface temperatures in the eastern tropical Pacific disrupt the normal atmospheric circulation. The large-scale convection moves eastward, closer to the coast of South America, leading to a weaker pressure gradient and weakened trade winds. As a result, less warm water is pushed towards the western Pacific, affecting the overall climate patterns globally.
To understand the Walker circulation and its behavior during normal and El Niño conditions, you can analyze various data sets and indicators. Here is how you can do it:
1. Use sea surface temperature data: Obtain historical sea surface temperature records of the tropical Pacific Ocean. You can access data from meteorological organizations or websites that provide climate data.
2. Identify El Niño events: Look for periods with abnormally warm sea surface temperatures in the eastern tropical Pacific. These are indicative of El Niño conditions. Compare these periods with those of normal or La Niña conditions, which are characterized by colder sea surface temperatures.
3. Analyze atmospheric pressure patterns: Access atmospheric pressure datasets, such as the Southern Oscillation Index (SOI), which measures the pressure differences between Tahiti and Darwin. Positive SOI values generally indicate normal conditions, while negative values suggest El Niño conditions.
4. Examine wind patterns: Study wind data, particularly the strength and direction of the trade winds in the tropical Pacific. Strong, consistent east-to-west trade winds indicate normal conditions, while weaker or even reversed trade winds indicate El Niño conditions.
By examining these various factors and their interactions, you can understand the differences between the Walker circulation patterns during normal and El Niño conditions. This knowledge can help in predicting and understanding weather patterns and climate variability in the tropical Pacific region.