La Nina

La Nina

News: Recently, Australia’s Bureau of Meteorology (BOM) predicted, that a third consecutive event of La Nina could be underway which could lead to unusual weather effects in various countries.

What is La Nina?
• La Nina means the Little Girl in Spanish. Often referred to as simply ‘cold event’.
• La Nina events represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific. It is indicated by sea-surface temperature decreased by more than 0.9℉ for at least five successive three-month seasons.
• La Nina event is observed when the water temperature in the Eastern Pacific gets comparatively colder than normal, as a consequence of which, there is a strong high pressure over the eastern equatorial Pacific.

Impact of La Nina on Different regions:
• In Europe, El Nino reduces the number of autumnal hurricanes. La Nina tends to lead to milder winters in Northern Europe (especially UK) and colder winters in southern/western Europe leading to snow in the Mediterranean region.
• It is continental North America where most of these conditions are felt. The wider effects include Stronger winds along the equatorial region, especially in the Pacific, favourable conditions for hurricanes in the Caribbean and central Atlantic area and Greater instances of tornados in various states of the US.
• In South America, La Nina causes drought in the South American countries of Peru and Ecuador. It usually has a positive impact on the fishing industry of western South America.
• In the western Pacific, La Nina increases the potential for landfall in those areas most vulnerable to their effects, and especially into continental Asia and China. It also leads to heavy floods in Australia. There are increased temperatures in Western Pacific, Indian Ocean and off the Somalian coast.

What is El Nino?
• El Nino is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean. It is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO). It occurs more frequently than La Nina.

Impacts of El Nino:
• El Nino also impacts ocean temperatures, the speed and strength of ocean currents, the health of coastal fisheries, and local weather from Australia to South America and beyond.
• Rainfall increases drastically in South America, contributing to coastal flooding and erosion.
• El Nino-related flooding is associated with increases in cholera, dengue, and malaria in some parts of the world, while drought can lead to wildfires that create respiratory problems.
• As El Nino brings rain to South America, it brings droughts to Indonesia and Australia. These droughts threaten the region’s water supplies, as reservoirs dry and rivers carry less water. Agriculture, which depends on water for irrigation, is also threatened.

What is ENSO?
• The combined phases of La Nina and El Nino are termed El Nino-Southern Oscillation (ENSO) and affect rainfall patterns, global atmospheric circulation, and atmospheric pressure across the planet.

Impact of 3 rd consecutive La Nina on India as predicted by IMD:
• The India Meteorological India (IMD) has predicted that some parts of India may witness heavy rains.
• The Western Ghats may receive average or below-average rain.
• Winter rainfall is likely to be less than normal in North India.
• Less than normal Winter temperatures in plain areas.
• Extended Winter Seasons over North India.
• More rain is expected during the second half of the Northeast Monsoon.
• Farmers are expected to be at risk of losing their standing Kharif crops as harvesting of Kharif crops begins in September end or early October and rains prior to that will not help farmers.