Monsoons, cyclones can be predicted more accurately now

A team from IISC, Bengaluru, and the UK based the University of East Anglia have recently created a blueprint under the ‘The Bay of Bengal Boundary Layer Experiment’ for accurate prediction of monsoon, tropical cyclones, and other weather-related forecasts.

BoBBLE (The Bay of Bengal Boundary Layer Experiment)

• It is a project funded by the Union Ministry of Earth Sciences and the Natural Environment Research Council of the UK.
• The researchers from a number of other institutions of repute from Kerala, Goa, Visakhapatnam, and Hyderabad were part of the project.
• The team has carried out studies of oceanographic properties onboard RV Sindhu Sadhana in the southern Bay of Bengal.
• After the studies, a blueprint for future weather system observational experiments was created for accurately forecasting rainfall.

Key processes in the southern BoB:

1. The saline Southwest Monsoon Current (SMC), a major control on the salt and SST distribution of the BoB, is shown to be controlled by both local (wind stress curl) and remote (equatorial wave propagation) factors, strongly linked to subseasonal variability over the wider Indian Ocean basin.
2. The high salinity core (HSC) of the SMC is shown to have its origins in the western equatorial Indian Ocean, reaching the BoB via the Somali Current, the Equatorial Undercurrent and the SMC.
3. Seasonal reversals that occur at the Somali Current and SMC junctions act as ‘railroad switches’ diverting water masses to different basins in the northern Indian Ocean.
4. Barrier layer formation and erosion in the southern BoB are found to be largely controlled by differential advection and resulting mixing driven by shear stress.
5. Chlorophyll in the southern BoB is strongly influenced by mixed layer processes and barrier layer strength.

What are monsoons?

• Monsoons are seasonal winds which reverse their direction with the change of season. The monsoon is a double system of seasonal winds. They flow from sea to land during the summer and from land to sea during winter.

• Monsoons are peculiar to Indian Subcontinent, South East Asia, parts of Central Western Africa etc.
• Indian Monsoons are Convection cells on a very large scale. They are periodic or secondary winds which seasonal reversal in wind direction.
• Monsoons are also often associated with conditions like ‘El Nino’ (Spanish for ‘Little Boy’) that occurs every 2 to 7 years and La Nina.

El Nino and Indian Monsoon

• El Nino is a narrow hot stream that flows near the Peruvian coast in December. In Spanish it is called “Child Christ” because this stream takes birth around Christmas.
• It is a temporary replacement for the Perubian or Humboldt cold current which usually flows along the coast.
• It flows once every three to seven years and is prone to large scale floods and droughts in tropical regions of the world.
• Sometimes it becomes very intense and raises the water temperature of the Peruvian coast by 10 ° C.
• This warming of the tropical waters of the Pacific Ocean affects the air pressure at the global level and the winds including the monsoon of the Indian Ocean.
• El Nino studies show that when the temperature in the southern Pacific Ocean increases, there is less rainfall in India.
• El-Nino has a great impact on the Indian monsoon and is used for forecasting the long period of monsoon.
• Meteorologists think that the 1987 severe drought in India was caused by El-Nino.
• In 1990–1991, El-Nino was seen as a severe form. Due to this, the arrival of monsoon in most parts of the country was delayed by 5 to 12 days.

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