0.1816
900 319 0030
x

Extreme Rainfall events - Central Indian Region

iasparliament Logo
October 06, 2017

What is the issue?

  • There is an increase in occurrence of extreme rainfall events in the central Indian region in recent years.
  • Reports suggest that an increased supply of moisture from Arabian Sea could be the reason.

What are the observations?

  • There is a trend of weakening summer monsoon winds between 1950 and 2015.
  • Resultantly, there has been an average 10% decline in overall summer monsoon rainfall over central India.
  • However, the frequency and intensity of extreme rainfall events during the same period in this region has been on the rise.
  • There has been a three-fold increase in the number of widespread extreme events in this region since 1950s.
  • Importantly, the northern Arabian Sea gets 1-2°C warmer, 2-3 weeks prior to extreme events.
  • As a result, there is 20-40% more evaporation and increased moisture levels over the Arabian Sea before an extreme event.
  • Notably, Arabian Sea supplies more moisture to the extreme rainfall events than the Bay of Bengal and the central Indian Ocean combined.

What are the causes?

  • For Weakening monsoon - Studies have observed that central Indian Ocean had considerably warmed over the years.
  • On the other hand, the Indian peninsular region had not warmed up compared to other regions in the tropics.
  • This is leading to a phenomena of reduced land-sea temperature difference.
  • This reduced temperature difference and possibly the cooling caused by aerosol are causes behind weakening of the monsoon winds.
  • For increased moisture - At the same time, the northern Arabian Sea is becoming increasingly warm.
  • This is leading to increased moist air over it.
  • Also, the warm temperatures result in large fluctuations in the monsoon winds leading to occasional surges.
  • Consequently, there is an increased moisture transport during such surges.
  • As monsoon winds blow northeastwards from Arabian Sea into India, this increased moisture causes extreme rainfall events in central India.

 

Source: The Hindu

1 comments
Login or Register to Post Comments

Rajesh 6 years

Why did  Indian peninsular region had not warmed up compared to other regions in the tropics . please explain

IAS Parliament 6 years

The decrease in land temperature of Indian Subcontinent is partly due to increased aerosol levels. Aerosols in the atmosphere reflect the sun’s heat back into space and cause a cooling effect. Also, the land is comparatively cooler than the surrounding Indian Ocean i.e there is a reduction in land-sea temperature contrast mainly due to strong warming in the Indian Ocean, which is due to climate change. Also refer https://www.iasparliament.com/article/role-of-aerosols-in-indian-monsoon?q=aerosols

ARCHIVES

MONTH/YEARWISE ARCHIVES

Free UPSC Interview Guidance Programme