Model Answer
0 min readIntroduction
The Indian monsoon, a defining feature of the Indian climate, delivers approximately 75% of the country’s annual rainfall. Its spatial and temporal distribution is crucial for agriculture, water resources, and the overall economy. However, the monsoon is known for its variability. The year 2017 witnessed an unusual monsoon pattern, characterized by significant spatial disparities – widespread flooding in parts of West India, particularly Gujarat and Maharashtra, alongside rainfall deficiency in East and Northeast India. This deviation from the normal pattern necessitated a detailed examination of the underlying meteorological factors.
Understanding the Normal Monsoon Pattern
The Indian monsoon is driven by the differential heating of land and sea. The southwest monsoon typically arrives over Kerala around June 1st and progressively covers the entire country. The normal monsoon pattern exhibits a gradient of rainfall, with the Western Ghats and Northeast India receiving the highest rainfall, while the leeward side of the Western Ghats and parts of the Northwest India receive comparatively less. The Intertropical Convergence Zone (ITCZ) plays a significant role in the monsoon’s movement and intensity.
The Unusual Rainfall Distribution in 2017
In 2017, the monsoon exhibited a highly uneven distribution. Key features included:
- Excess Rainfall in West India: Gujarat and Maharashtra experienced exceptionally heavy rainfall in late August and early September, leading to severe flooding and displacement of populations.
- Rainfall Deficiency in East and Northeast India: States like Bihar, Jharkhand, West Bengal, and parts of the Northeast experienced significant rainfall deficits, impacting agricultural production.
- Delayed Onset and Initial Weakness: The monsoon onset was delayed, and the initial phase was relatively weak, raising concerns about a drought-like situation.
- Prolonged Rainfall in September: While the monsoon usually starts withdrawing by September end, 2017 saw prolonged rainfall activity extending into the first week of October.
Reasons for the Anomalous Distribution
1. Break in Monsoon and its Revival
The initial phase of the monsoon in 2017 was characterized by a prolonged ‘break’ in monsoon conditions. This was due to the weakening of the monsoon trough and the absence of favorable upper air circulation. However, a subsequent revival of the monsoon trough, coupled with the formation of low-pressure systems in the Bay of Bengal and the Arabian Sea, led to concentrated rainfall in West India.
2. Role of Western Disturbances
Western disturbances, extra-tropical storms originating in the Mediterranean region, played a crucial role in enhancing rainfall over Northwest India. However, in 2017, their influence was less pronounced, contributing to the rainfall deficiency in that region. The interaction of these disturbances with the monsoon trough was also not optimal.
3. Madden-Julian Oscillation (MJO)
The MJO, a travelling disturbance in the tropics, significantly influences the monsoon’s activity. In 2017, the MJO was in a phase that favored enhanced rainfall over the Indian subcontinent, particularly during the latter half of the monsoon season. This contributed to the heavy rainfall in West India.
4. El Niño-Southern Oscillation (ENSO)
While a weak La Niña was present during 2017, its influence on the Indian monsoon was not as strong as expected. Typically, La Niña conditions are associated with a good monsoon, but the other factors mentioned above overrode this influence, leading to the uneven distribution.
5. Arabian Sea Cyclogenesis
The Arabian Sea witnessed increased cyclogenesis in 2017, with the formation of Cyclone Ockhi. This cyclone contributed to the heavy rainfall in coastal areas of Gujarat and Maharashtra. The warm sea surface temperatures in the Arabian Sea provided favorable conditions for cyclone development.
Regional Variations and Impacts
| Region | Rainfall Status (2017) | Impact |
|---|---|---|
| Gujarat | Excess (+33%) | Severe Flooding, Agricultural Losses, Displacement |
| Maharashtra | Excess (+23%) | Flooding in Mumbai and other cities, Infrastructure Damage |
| Bihar | Deficit (-29%) | Drought-like conditions, Reduced Agricultural Output |
| West Bengal | Deficit (-22%) | Impact on Paddy Cultivation, Water Scarcity |
(Data based on India Meteorological Department (IMD) reports, knowledge cutoff 2023)
Conclusion
The unusual monsoon pattern of 2017 highlights the complex interplay of various meteorological factors influencing the Indian monsoon. While the MJO and Arabian Sea cyclogenesis contributed to excess rainfall in West India, the subdued influence of Western Disturbances and a weak La Niña led to rainfall deficiency in East and Northeast India. This underscores the need for improved monsoon prediction models, enhanced disaster preparedness, and sustainable water management practices to mitigate the impacts of monsoon variability. Further research into the regional variations of monsoon patterns is crucial for effective policy planning.
Answer Length
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