- India’s National Centre for Polar and Ocean Research (NCPOR), under the Ministry of Earth Sciences, and South Korea’s Korea Polar Research Institute’s study have found that seasonal changes in the Arctic Sea ice affect the Indian monsoon.
| Arctic Ice | Reduced | Increased |
| Low Sea Ice in the Central Arctic | Rainfall in Western and Peninsular India | Rainfall in Central and Northern India. |
| Low Sea Ice in Barents-Kara Sea | Delayed Monsoon Onset | Monsoon Unpredictability and Extreme Weather Events |
Table 1 Role of Declining Arctic Sea Ice in Monsoon Variability
- The ISMR (Indian Summar Monsoon Rain) is a complex phenomenon, climate models have shown that the surface temperatures of the Indian, Atlantic, and Pacific Oceans affect it.
- The circum-global teleconnection (CGT) seemed to significantly infl uence the monsoon as well.
- On the contrary, the scientists also found that when sea ice levels in the central Arctic increase, the heat transferred from the ocean to the atmosphere triggers a cyclonic circulation at slightly lower latitudes, like in the North Atlantic. This also bolsters Rossby waves.
| Circum-global Teleconnection: It is a large-scale atmospheric wave flowing at the mid-latitudes. Rossby waves: Rossby waves are fast-flowing streams of air, high in the atmosphere created by the earth’s rotation and differences in temperature and weather systems that move west to east. |
- The enhanced Rossby waves result in high pressure over northwest India and low pressure over the Mediterranean region.
- As a result, an anomalous high-pressure region is created over Central Asia, disrupting atmospheric stability over the Indian landmass and bringing more rain over western and peninsular India.
| Indian Summer Monsoon Rain (ISMR): • It occurs between July and September. • In summer, the Central Asian and Indian landmass get warmed faster than the surrounding ocean creating a low-pressure band at the Tropic of Cancer called the intertropical convergence zone (ITCZ). • Trade winds blowing from the southeast are subsequently deflected towards the Indian landmass due to the Coriolis force and have low pressure after they cross the equator. • As they blow over the Arabian Sea, the winds pick up moisture and deposit that as rain over India. • These winds split into two branches: one brings rain to the west coast, while the other moves towards eastern and northeastern India. • The branches converge over northern India, impacting large parts of the country. |
Dig Deeper: Read more about Rossby waves.
