Northeast Monsoon: Mechanisms and Impact on Indian Climate

Understanding the Northeast Monsoon Phenomenon

The northeast monsoon, commonly referred to as the 'retreating monsoon,' is a significant weather phenomenon impacting the Indian subcontinent. This seasonal wind pattern brings essential rainfall to specific regions of India during the winter months, especially from October to December.

Mechanisms of the Northeast Monsoon

Understanding the dynamics of the northeast monsoon is crucial for grasping its influence on the Indian climate:

• Withdrawal of the Southwest Monsoon: The northeast monsoon follows the vigorous southwest monsoon, which typically delivers heavy rainfall across India from June to September. As this southwest monsoon weakens and withdraws, a transitional phase occurs prior to the onset of the northeast monsoon.
• Onset Timing: The northeast monsoon generally begins in October, targeting the southern and eastern parts of India. However, the exact timing may vary each year, influenced by various climatic factors.
• Weak Monsoon Characteristics: Often considered a 'weak' monsoon, the northeast monsoon delivers less rainfall than its southwest counterpart. Its intensity can fluctuate based on multiple atmospheric conditions.
• Regional Impact: This monsoon primarily affects southern and southeastern India, particularly states like Tamil Nadu, Kerala, Karnataka, and portions of Andhra Pradesh. These regions rely heavily on the northeast monsoon for significant rainfall.
• Contribution to Annual Rainfall: Despite its importance, the northeast monsoon accounts for only about 11% of India’s total annual rainfall, a factor that underscores its regional significance.
• Variability in Performance: The performance of the northeast monsoon can vary significantly from year to year. While some years may see heavy rainfall and flooding, others may experience a weaker monsoon, leading to water shortages.

The northeast monsoon plays a vital role in supporting agriculture and water supply in the affected regions. Meteorological agencies closely monitor its onset and performance to assess potential impacts on agriculture and water resources.

Recent Observations and Predictions

As of late September, the India Meteorological Department (IMD) announced the anticipated start of the northeast monsoon within 72 hours, following the withdrawal of the southwest monsoon from Rajasthan. Although the southwest monsoon concluded with a rainfall rate of 94% of the expected levels, the IMD forecasts a 'normal' northeast monsoon for October to December.

Forecasts indicate that regions like Tamil Nadu, Kerala, Karnataka, and parts of Andhra Pradesh will play a crucial role in receiving this rainfall, which is essential for their agricultural cycles. Historical trends show variability, as demonstrated by the severe floods in Chennai in 2015 and a notably weak northeast monsoon in 2019.

Additionally, the IMD has reported the development of low-pressure areas in the Arabian Sea and Bay of Bengal, which could potentially intensify into depressions by mid-October, further influencing the monsoon's behavior.

Frequently Asked Questions (FAQs)

Q1. What is the northeast monsoon?
Answer: The northeast monsoon is a seasonal wind pattern in India, occurring from October to December, primarily affecting the southern and southeastern regions with rainfall.

Q2. How does the northeast monsoon differ from the southwest monsoon?
Answer: The northeast monsoon typically brings weaker rainfall compared to the southwest monsoon, which occurs from June to September and delivers more intense precipitation.

Q3. Which states in India are most affected by the northeast monsoon?
Answer: The northeast monsoon primarily impacts Tamil Nadu, Kerala, Karnataka, and parts of Andhra Pradesh, providing crucial rainfall for these regions.

Q4. What percentage of India's annual rainfall does the northeast monsoon account for?
Answer: The northeast monsoon contributes about 11% of India's total annual rainfall, highlighting its importance for regional water supply and agriculture.

Q5. Why is there variability in the northeast monsoon's performance?
Answer: The performance of the northeast monsoon can vary due to climatic conditions, leading to years with heavy rainfall or weaker seasons causing water shortages.

UPSC Practice MCQs

Question 1: What is the primary impact of the northeast monsoon in India?
A) It causes heavy flooding across all regions
B) It brings winter rainfall to southern and southeastern India
C) It replaces the southwest monsoon completely
D) It is the main source of annual rainfall in India
Correct Answer: B

Question 2: When does the northeast monsoon typically begin?
A) June
B) September
C) October
D) December
Correct Answer: C

Question 3: Which state does NOT primarily benefit from the northeast monsoon?
A) Tamil Nadu
B) Maharashtra
C) Kerala
D) Karnataka
Correct Answer: B

Question 4: What is the expected contribution of the northeast monsoon to India's annual rainfall?
A) 5%
B) 11%
C) 25%
D) 35%
Correct Answer: B