"El Niño Linked to Repeated Monsoon-Season Swell Surges in Kerala"
Swell surge
high, long-period waves from a distant storm striking a coast, called kallakadal in Kerala and Tamil Nadu.
Storm surge
local sea-level rise caused directly by a cyclone's own winds and pressure field.
India's coastline runs over 7,500 km, with the southwestern stretch, covering Kerala and southern Tamil Nadu, facing the open Arabian Sea. This makes it directly exposed to wave energy generated far out at sea. The Indian National Centre for Ocean Information Services (INCOIS), headquartered in Hyderabad under the Ministry of Earth Sciences, is India's nodal agency for ocean-hazard forecasting. It issues tsunami warnings, storm surge alerts, and swell surge advisories, and also runs the Indian Tsunami Early Warning Centre (ITEWC). Coastal disaster response is coordinated under the Disaster Management Act, 2005, which created the National Disaster Management Authority (NDMA) at the apex level, with State Disaster Management Authorities handling ground-level action. India has also committed to the Sendai Framework for Disaster Risk Reduction (2015-2030), which calls for universal access to multi-hazard early warning systems.
This year's swell surge pattern is tied to El Niño, the periodic warming of sea surface temperatures in the central and eastern Pacific Ocean. El Niño years often weaken the Indian monsoon's usual winds and rainfall. A separate but related phenomenon, the Indian Ocean Dipole (IOD), is defined by the temperature difference between the western and eastern tropical Indian Ocean, not the Pacific. A positive IOD phase can offset El Niño's suppressing effect on the monsoon, while a weak or negative IOD lets El Niño's impact show through more clearly. This year, Kerala has recorded a 28% rainfall deficit in the monsoon season, consistent with El Niño's usual dampening effect, even as unusually calm seas have let distant swells become far more noticeable along the coast.
A swell surge is different from a storm surge or a tsunami, even though all three cause seawater to flood the coast. A storm surge is generated locally, when a cyclone's strong winds and low pressure push seawater onto the shore. A tsunami results from a sudden seismic or volcanic disturbance of the seabed. A swell, by contrast, is a long-period wave generated by a distant storm or a sustained period of strong gale winds, often thousands of kilometres away. During such storms, enormous energy transfers from wind into water, and the resulting waves keep travelling as organised, long-period swells long after the storm itself has died down. …
With reference to 'Indian Ocean Dipole (IOD)' sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?
1.IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
2.An IOD phenomenon can influence an El Nino's impact on the monsoon.
Select the correct answer using the code given below:
Comment on the resource potentials of the long coastline of India and highlight the status of natural hazard preparedness in these areas.
Consider the following statements:
1.The Indian Ocean Dipole refers to the difference in sea surface temperature between the tropical western Indian Ocean and the tropical eastern Pacific Ocean.
2.A positive Indian Ocean Dipole phase can moderate the adverse impact of El Niño on the Indian monsoon.
Which of the statements given above is/are correct?
Consider the following statements regarding swell surge:
1.It is generated by strong winds acting locally within the same coastal region, similar to a storm surge.
2.Swell waves can travel thousands of kilometres from a distant storm before striking a coast.
3.In India, swell surge alerts are issued by the India Meteorological Department (IMD).
Which of the statements given above is/are correct?
Match List I (Phenomenon) with List II (Defining Characteristic) and select the correct answer using the code given below:
List I:
A.Swell surge
B.Storm surge
C.Tsunami
D.Indian Ocean Dipole
List II:
1.Sea-level rise driven directly by a cyclone's wind and pressure field
2.Long-period waves reaching a coast from a distant storm
3.Sudden displacement of ocean water due to seismic or volcanic activity
4.Sea-surface-temperature difference between western and eastern tropical Indian Ocean
Which of the following statements about the Indian National Centre for Ocean Information Services (INCOIS) is/are correct?
1.It functions under the Ministry of Earth Sciences.
2.It is headquartered at Hyderabad.
3.It operates the Indian Tsunami Early Warning Centre.
Select the correct answer using the code given below:
Which of the following best explains why swell surges strike the coast of southern Kerala and Kanyakumari with greater intensity than other stretches of India's western coast?
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