El Nino Weather Conditions & Its Impacts

El Nino Southern Oscillation (ENSO):

• ENSO is a global phenomenon, which affects the temperature and precipitation of many regions around the globe, including the Indian subcontinent. 
• The most important factor with the ENSO is the ability of the scientists to predict its occurrence, thereby predicting the amount of rainfall and temperature in the region.

El Nino

• This is a name given to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current.
• ‘El Nino’ is a Spanish word meaning ‘the child’, and refers to the baby Christ, as this current starts flowing during Christmas.
•  The presence of the El Nino leads to an increase in sea-surface temperatures and a weakening of the trade winds in the region. 
• In a normal monsoon year (without El Nino), the pressure distribution along the coast of Peru in South America has a higher pressure than the region near northern Australia and South East Asia.

Impact 

• The outcomes of each El Niño event are never exactly the same: they depend on the intensity of the event, the time of year when it develops and the interaction with other climate patterns.
• El Niño is often associated with warm and dry conditions in southern and eastern inland areas of Australia, as well as Indonesia, the Philippines, Malaysia and central Pacific islands such as Fiji, Tonga and Papua New Guinea. 
• During the northern hemisphere summer season, the Indian monsoon rainfall generally tends to be less than normal. 
• In the northern hemisphere winter, drier than normal conditions are typically observed over south-eastern Africa and northern Brazil.
• Wetter than normal conditions are typically observed along the Gulf Coast of the United States, the west coast of tropical South America (Colombia, Ecuador and Peru) and from southern Brazil to central Argentina. 
• Parts of eastern Africa (Kenya, Uganda) also usually receive above-normal rainfall. 
• El Niño is associated with milder winters in north-western Canada and Alaska due to fewer cold air surges from the Arctic – a result of a large-scale region of lower pressure centred on the Gulf of Alaska/North Pacific Ocean.

Image Courtesy: WMO