Why is the Indian Monsoon Erratic in Nature? Explain
(UPSC geography optional paper 2 2019, 10 Marks)
Answer:
Table of Content
- El Nino
- Na Nina
- Oceanic Nino Index( ONI)
- Southern Oscillation( SO)
- SOI- Southern Oscillation Index
- ENSO-El Nino Southern Oscillation
- India Ocean Dipole-IOD
- Effect of these in Indian Monsoon
El-Nino:
The Southwest Pacific margin ( Peruvian Coast) is warmer more than 0.5 degrees centigrade than the then southeast Pacific margin( Australian Coast), this situation is called El -Nino. It is about a 3-month session.
La-Nina:
Opposite the El Nino ocean situation is called La-Nina. In La-Nina, the Peruvian coast is cooler compared to normal ocean temperature.
 |
| El Nino and La Nina |
Oceanic Nino Index( ONI):
ONI=Surface Temperature of the pacific ocean along with northwestern South America- Surface Temperature of the pacific ocean along with North-East Australia, Indonesia, and the Philippines.
If ONI is greater 0.5
than strong EL-Nino
else if ONI is between 0.1 to 0.5
weak El-Nino
else if ONI is less than 0
than Na-Nina or normal year
Southern Oscillation ( SO):
Gilbert Walker British Mathematician discovered the southern oscillation; a large-scale change in sea level atmospheric pressure across Indonesia and the tropic of the Pacific.
Many global climates including monsoon is a correlation with SO.
It gives the intensity of El Nino and LA Nino.
SOI=atmospheric pressure of Tahiti( South Pacific ocean)-atmospheric pressure of Darwin( Australia)
If SOI is positive
LA NinaSOI=atmospheric pressure of Tahiti( South Pacific ocean)-atmospheric pressure of Darwin( Australia)
If SOI is positive
Else
El Nino
- ENSO refers to the oscillation between EL Nino and LA Nina alternatively.
- Changes in Ocean temperature and atmospheric pressure are connected to each other; together concept is called ENSO.
- Each phase triggers predictable disruption of temperature, precipitation, and wind leading to cascading effects at the global level atmospheric circular such as monsoon.
- Flood in Peru, Ecuador, Mexico, USA.
- Drought in Australia, India, and southern Africa.
Effect of EL-Nino and ENSO on Indian Monsoon:
- Scientists and researchers found no direct correlation between ENSO and Monsoon but by observation, it is found that:
- All LA Nina years, above than normal monsoon;
- Not all El Nino but most of it resulted in normal Monsoon.
- From 1997 -to 98; El Nino strong but above average monsoon in India.
- In 2002; although week El Nino observed but high drought in India.
IOD-Indian Ocean Dipole:
- It is referred to as a swing in sea surface temperature in the western and eastern Indian ocean, which is known as Indian Ocean Dipole.
- Positive IOD can cater to EL-Nino Effect
- Weak IOD negatively affects the monsoon.
- Warming up of the west Indian ocean boosts monsoon rain.
- IOD number = temperature of the Arabian sea - the temperature of the eastern Indian ocean at the Indonesian coast.
- If IOD is greater than 0
- Good monsoon
- Else
- Below average monsoon.
Factors affecting Indian Monsoon:
- EL-Nino
- Na-Nina
- ENSO
- IOD
- Heating of Tibetan Plateau from April to June month
- Himalayan and Eurasian snow cover.
- Less snow cover means warmer subcontinent will bring more rain.
- Tropical Easterly Jet
- Presence of High-pressure areas in the Madagascar region
Try to solve the following questions:
- Discuss the major characteristics of the Indian monsoon with special emphasis on the causative factors( UPSC 1922)
- Discuss the recent theories put forward to explain the origin and mechanism of the Indian Monsoon. ( UPSC, 1994)
- Elucidate the mechanism of the Indian Monsoon( UPSC, 1999)
- Explain the Origin, Mechanism, and characteristics of the Summer Monsoon in India. ( UPSC 2002)
- Give a Critical account of the recent theories of the origin of the Indian monsoon with special reference to the Jet Stream Theory. (UPSC, 2006)
- Discuss the mechanism and origin of Monsoon winds and explain the role of El Nino on Monsoon circulation. ( UPSC, 2008)
- Discuss the mechanism of the Indian Monsoon (UPSC 2013)
- Discuss the nature and origin of the Indian monsoon and recent techniques for its prediction. ( UPSC, 2014)
- Give a reasonable account of the Unusual Pattern of Distribution of Monsoonal rainfall in India. ( UPSC, 2017)
- Why is the monsoon erratic in nature? Explain. ( UPSC 2019)
- Explain the origin, progress, and retreat of the Indian monsoon and discuss its impact on the Indian economy. (UPSC 2018, 250 words, 20 marks)
- Elaborate on the origin of monsoon with reference to thermal and recent concepts. ( UPPSC 2020)
You may like also:
- Origin and Mechanism of Indian Monsoon
- Rainfall Pattern of Indian Monsoon
- Jet stream theory of Monsoon
- Characteristics or Nature of Indian monsoon
- Air Mass Theory of Monsoon or ITCZ theory
- Thermal theory of monsoon by Halley
- El Nino | La Nina |SO| ENSO| IOD-Indian Ocean Dipole
- Elaborate on the origin of monsoon with reference to thermal and recent concepts.
- Recent Theory of Origin and Mechanism of Monsoon
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