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Abstract Submission No. | ABS-2022-04-0047 |
Title of Abstract | Seasonal and Cyclonic Wind-Wave Relationship from Moored Buoy Measurements in the South-East Arabian Sea Considering Local and Remote Wave Effects |
Authors | Dr M Kalyani*, Dr K Jossia Joseph, Dr G Latha, Dr R Venkatesan |
Organisation | NIOT |
Address | OOS Group, NIOT, Pallikaranai, Chennai CHENNAI, Tamilnadu, India Pincode: 600042 Mobile: 6379790256 E-mail: kalyani.niot00@gmail.com |
Country | India |
Presentation | Oral |
Abstract | Wind and wave characteristics are site specific in nature. They vary seasonally with varying sea-states. The available wind-wave relationships are primarily based on empirical relations for equilibrium and neutral conditions. These are generally linear relations with constant coefficient which do not account for the varying wind conditions such as wind intensity and direction. Moreover, wave characteristics at a specific location include the effects of local wind waves (wind seas) as well as remote forcing (swells). The coefficients applicable for one location may not describe the characteristics satisfactorily at another location and hence may not be applicable. The linear relations may not suffice during high intensity events such as cyclones and may need to resort to nonlinear relationships for better description and assessment. Though the frequency and the intensity of cyclones is less in the Arabian Sea when compared to that of the Bay of Bengal, the climate change effects are altering the scenario rapidly. This speaks of the dire need for establishing a better relationship between winds and waves, especially wherever the observations are available. Observed data of both winds and waves are needed to formulate effective empirical relations, alleviating above mentioned inadequacies. The dynamic nature of the relationship under varying seasons, demands at least yearlong measurements at any location. Long-term measurements can bring out the inter-annual variation. In situ observations with high temporal resolution are necessary to capture the intricacies of the dynamics. Considering the above fact, the continuous high resolution wind and wave measurements obtained from OMNI buoy of ESSO-National Institute of Ocean Technology on the southeast Arabian sea in deep waters have been utilized to establish the wind-wave relationship. The South-east Arabian Sea is characterized by swells originating from Southern Indian Ocean. It is also under the influence of seasonal wind reversal and Indian monsoons. Seasonal variability of wind intensity, and direction, local and remote effects (seas & swells) of waves, as well as nonlinear variation during cyclones are taken into account. These established empirical relations can be utilized to obtain oceanic parameters (wave) from meteorological observations alone (wind) with reasonably good accuracy at that site. |