Why Monsoon plays a significant role for India?

Indian Meteorological Department has predicted a normal monsoon this year. In its Long Range Forecast (LRF) it has predicted a normal or above normal in most parts of the country except North-East, Haryana and Jammu Kashmir.

• The IMD predicts a “normal”, “below normal”, or “above normal” monsoon in relation to a benchmark “long period average” (LPA).
  • According to the IMD, the “LPA of rainfall is the rainfall recorded over a particular region for a given interval (like month or season) average over a long period like 30 years, 50 years, etc”.

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What is Monsoon?

• The word monsoon derive from the Latin word ‘mausam’. It is a geographical phenomenon of seasonal reversal of winds.
• Monsoon season: There are two monsoons (or rainy seasons) in India.
  • Summer Monsoon: The summer monsoon season in India, otherwise known as the southwest monsoon, which lasts from June to September and affects the whole of India.
  • Winter Monsoon: Then the northeast or winter monsoon brings seasonal rainfall to Southeast India from October to December
    
    

• Monsoons are caused by a pressure difference between sea and land, bringing seasonal winds and rains.

• Southwest monsoon
• The southwest monsoon occurs after the hot summer. The huge landmass of India heats up at a different rate to the surrounding sea, and the extreme heat of the Thar Desert in Rajasthan draws in moisture-laden winds from the low-pressure area in the Arabian sea.
• The winds first hit the Western Ghats of Kerala, this land relief causes the air to rise and cool with subsequent rainfall, they then move northwards.
• The rains reach Kerala around the beginning of June, usually arrive in Mumbai approximately 10 days later, then Delhi by the end of June, and the rest of India by mid-July.

• Reverse Monsoon

• The reverse happens in winter, during the northeast monsoon.
• The land is colder than the sea, so the pressure gradient is from land to sea.
• Winds blow over the Indian subcontinent toward the Indian Ocean in a northeasterly direction, passing over the Bay of Bengal picking up moisture, and causing rain in Tamil Naduin October – November.

Ideally more than 63 factors are taken into consideration for predicting the onset of monsoon. Many theories have been developed to explain the onset and factors responsible for monsoon. Despite several changes and developments it still remains unpredictable. There are several factors and geographical phenomena which influence the onset of monsoon as follows:

• Shift of ITCZ:
  • During the summer season in the month of June the sun rays makes normal near Tropic of Cancer. This results into shift of Inter Tropical Convergence Zone (ITCZ) which is generally lies near equator. This shift creates a shift of low pressure belt from equator to Tropic of Cancer.

• Shift in ITCZ brings the easterlies from south hemisphere to north hemisphere. Due to presence of coriolis force when south easterlies wind crosses the equator the direction changes towards rightwards and becomes west winds, because of this change in direction of the winds it is known as South-West Monsoon.
• Presence of Tibetan Plateau (Kotteswaram Theory):
  • A large table top area in north of India, i.e., Tibentan Plateau. A large uniform landmass gets heated up faster as compared to uneven surface. This resultys in formation of a low pressure region at the north of India.
  • This Development of low pressure region just above India gives an extra pull to the south west winds towards India.

• Mascarene high:
• • When sun makes a normal near Tropic of Cancer a high pressure region develops near Mascarene Island known as Mascarene high. This high pressure region creats a atmosphere circulation with Tibetan low pressure region and push the southwest monsoon to move towards India.
• Condition of La-Nina: (Creates a positive impact on Monsoon)
  • Tropical winds blow from east to west which takes the surface warm water of the ocean from eastern part of the ocean to western part of the ocean.
  • Tropical easterlies in south hemisphere bring the warm ocean water from east Pacific (Western boundary of South America) to West Pacific (Easter boundaries of Australia). The presence of warm water near Australia develops a new low pressure region. This condition is termed as La-Nina.
  • Low pressure from Western Pacific creates a circulation with Mascarene high pressure region. This circulation provides extra moisture to the circulation between Mascarene high and Tibetan low.
  • Presence of La-Nina in the west Pacific supplies more moisture to the South west monsoon.
• Condition of El-Nino (negative impact on south west Monsoon):
  • Due to some atmospheric disturbances tropical easterlies in southern hemisphere becomes weak for certain time period. Weakening of tropical easterlies could not bring the warm water to western pacific and the warm water gets distributed over the ocean. This condition is coined as El-nino
  • Presence of El-nino disturbs the formation of low pressure region over Australia and the formation of circulation between Australia and Mascarene high, which again impact the supply of moisture to the southwest monsoon.
  • Presence of El-nino creates deficit rain in India during monsoon.
• El-nino and La-Nina Modoki:
  • El-Nino Modoki: Modified El-Nino, means a break in the El-Nino in the middle pf the Pacific Ocean which reduces the impact of El-Nin0. This creates a positive impact on southwest monsoon.
  • La-Nina Modoki: La-Nina Modified, means break of La-Nina in the middle of Pacific ocean creates a negative impact on Indian monsoon
• Indian Ocean Dipole (IOD): Development of two poles in the India Ocean, one near Mascarene Island and other near Australia.
  • Positive IOD: Strong circulation between Australia and Mascarene high creates a surplus supply of moisture to the South west wind and creates positive impact on Indian Monsoon.
  • Negative IOD: Weaker circulation between Australia and Mascarene island creats a deficit supply of moisture to the south west wind and has a negative impact on Indian Monsoon.
• Madden-Julian Oscillation:
  • Atmospheric oscillation at a smaller region on the Indian ocean for a shot time period, which changes its position from Madagascar to Australia due to uneven heating of the ocean. The position of MJO has a significant influence on the Indian South west monsoon.
• Jet streams:
  • Presence of jet streams has an influence on the nature and formation of low pressure in the north of India. The movements of jet streams are 3-dimentional which can bend in any way any direction and creates an influence on the monsoon.

• Resetting of Tropical Easterlies:
  • In the month of September the sun changes its position from north to south hemisphere which also brings down the ITCZ towards south near Tropic of Capricorn.
  • This movement of ITCZ gives the space for Tropical Easterlies for retake their position.
  • This resetting of tropical easterlies influence the retreating monsoon.

• Being an agrarian economy more than 50% of the population is depend upon agriculture for their livelihood. Availability of water becomes a major factor for agricultural practices.
• Due to several socio-economic conditions there are barriers for the farmers to adopt new irrigational technologies as a result most of the agricultural practices depends on the onset of monsoon.
• The major cropping season for India that Kharif season is totally based on the monsoon rainfall. Unpredictable monsoon decides the food security and income of the Indian farmers.

• Food security: Unpredictable monsoon has the potential to influence the socio economical political change for India. India’s major food crops and staple food diets involves the onset of monsoon. If there is deficit of monsoon that can create an issue of major food security for India.
• Food Inflation: Supply disruption of food crops due to disturbances in monsoon has an impact on food inflation which may give rise to cost push inflation.
• Social welfare: Disruption in monsoon rain can bring down the farmers income and can widen the income gap in the society. To sustain the crop and low income the chances of informal loans by the farmers and debt trap increases.

• Agricultural infrastructure: development agricultural infrastructure like better irrigation facilities and storage system can be developed to reduce the dependence on southwest monsoon.
• Crop Insurance: Increasing the insurance penetration in the rural economy can protect the farmers from crop losses and hindered income.
• Formal credit line penetration: Penetration of formal banking sector and credit line in the rural economy will reduce the chances of debt trap for the farmers.
• Crop diversification: crop diversification towards less water intensive crop.
• Economic diversification: The rural economy needs to be diversified towards various other sources of income and industries like food processing, etc.
• Skill development and Self Help Groups: skill development among the youth and penetration of Self Help Groups among rural households can diversify their income sources.

Considering several factors of monsoon it is still quite unpredictable and. New technologies and advancement can improve the accuracy in the prediction. Along with the better prediction it is also necessary to protect the welfare and interest of the farmers of our country.