Western Disturbances impacts and play a crucial role in shaping climatic conditions across the Indian subcontinent. These disturbances, coupled with phenomena like El Niño and La Niña, have far-reaching consequences on weather patterns and agricultural output.

Understanding El Niño and La Niña:

• El Niño: This climate pattern signifies abnormal warming of surface waters in the eastern equatorial Pacific Ocean. In India, El Niño tends to lead to reduced rainfall, while increasing rainfall over the central and eastern tropical Pacific Ocean.
• La Niña: In contrast, La Niña denotes a pattern characterized by unusual cooling of surface waters in the eastern equatorial Pacific Ocean. Over India, La Niña typically brings increased rainfall, but it decreases rainfall over the central and eastern tropical Pacific Ocean.
• El Niño-Southern Oscillation (ENSO): ENSO is a recurring climate phenomenon involving temperature fluctuations in the central and eastern tropical Pacific Ocean. This oscillating warming and cooling pattern happens every three to seven years and has a notable impact on global weather.

Defining Western Disturbances:

• Western Disturbances are cyclonic storms originating over land, primarily occurring in the Mediterranean region. They stem from a temperature gradient generated by the intermingling of warm air from the tropics and cold air from northern polar regions.
• While these storm systems can develop throughout the year, they typically reach India between December and April, guided by the subtropical westerly jet stream.
• The intensity of Western Disturbances is influenced by El Niño and the North Atlantic Oscillation.

Impacts of Western Disturbances in India:

• These low-pressure storm systems significantly benefit Indian farmers in cultivating the rabi crop. They bring crucial snowfall to the Himalayas, and help maintain the flow of northern rivers.
• Western Disturbances accumulate moisture from the Mediterranean Sea, Black Sea, and Caspian Sea, traveling across Iran and Afghanistan before reaching the western Himalayas. Strong Western Disturbances can extend their influence to the central and eastern Himalayas, triggering rain and snowfall in Nepal and northeastern India.

Climate Change’s Effect on Western Disturbances:

• The changing nature of Western Disturbances is responsible for India’s abnormal winter seasons since 2020-21. These disturbances, which bring winter rains to northwest India, have started visiting the region more frequently during the summer.
• Western Disturbances, when they arrive late, interact with tropical cyclones, providing them with the warm surface temperatures and wind shear needed to sustain themselves. This interaction played a role in the Uttarakhand floods of June 2013, which resulted in substantial casualties and damage.
• Global warming could potentially disrupt the temperature gradient in the Mediterranean that is essential for the formation of Western Disturbances.

The complex interplay of Western Disturbances and global climate phenomena underscores the necessity of monitoring. Understanding these weather patterns to mitigate potential risks and adapt to changing climatic conditions.

Also Read: La Niña