Context:
Recently, swell waves inundated coastal areas in central and southern districts of Kerala.
Relevance:
GS I: Geography
About Swell Waves
- Definition: Swell waves are long-wavelength waves that form on the ocean surface, comprised of a sequence of surface gravity waves.
Formation of Swell Waves
- Cause: Swell waves are not generated by local winds. Instead, they are formed due to distant weather phenomena such as hurricanes or prolonged periods of strong gale winds.
- Energy Transfer: During these distant storms, significant energy is transferred from the atmosphere to the ocean, resulting in the creation of exceptionally high waves. These waves can travel vast distances, sometimes thousands of kilometres from the storm’s epicentre, until they reach the shoreline.
Characteristics of Swell Waves
- Frequency and Direction: Swells exhibit a narrower range of frequencies and directions compared to wind waves generated locally. This is because swell waves disperse from their origin, lose some randomness, and assume a more defined shape and direction.
- Propagation: Swell waves can travel in directions that are distinct from the wind’s direction, unlike wind-generated waves.
- Wavelength: The typical wavelength of swell waves is under 150 metres, but it can vary between different events. In extreme cases, swell waves from the most intense storms can have wavelengths exceeding 700 metres.
- Precursors: Swell waves can occur without any precursors or local wind activity, making them distinct from other wave types.
Early Warning Systems in India
- Swell Surge Forecast System: Launched by the Indian National Centre for Ocean Information Services (INCOIS) in 2020, this system provides a seven-day advance warning about swell surges, helping to mitigate potential risks and prepare coastal communities in India.
-Source: The Hindu
