- Dona Paula, Goa, India.
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- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-14-0114 |
| Title of Abstract | An integrated SWAN+WAVEWATCH III modeling system for the Indian coast-development and validation |
| Authors | Sandhya K G*, Aditya N Deshmukh, PLN Murty, Siva K Srinivas, Remya P G, Dr. Francis P A, Dr. T M Balakrishnan Nair |
| Organisation | Indian National Centre for Ocean Information Services |
| Address | INCOIS, Hyderabad, Telangana, India Pincode: 500090 Mobile: 8019596800 E-mail: sandhyakg@incois.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | India is a peninsular country with Arabian sea to the west, Bay of Bengal to the east and Indian Ocean to its south. This densely populated country with a population of approximately 1.3 billion has many of its major cities like Mumbai, Kolkata, Chennai, etc., on its coasts. The high density coastal belts along with India's blue economy initiatives have led to rapid increase in marine activities in the recent times. The increase in the number of vessels at the sea has resulted in a surge in planning and operational activities at ports and harbours, and in turn, an increasing number of vessel-related hazards like oil spills, etc. In India, Indian National Centre for Ocean Information Services (INCOIS), an autonomous organisation under the Ministry of Earth Sciences, is mandated to issue ocean information operationally to the Indian ocean, including the coastal regions of India, and the Indian Ocean rim countries. INCOIS issues forecasts of sea state parameters such as waves, currents, sea surface temperature, etc. up to 10 days in advance for the parameters such as significant wave height, wave direction, wave period, wave energy, etc. The forecasting system is forced with high quality winds from European Centre for medium-range Weather Forecasts (ECMWF), National Centre for Medium-Range Weather Forecasts (NCMRWF), Weather Research and Forecasting model (WRF), etc. and is validated thoroughly using a vast observational network which constitutes wave rider buoys, moored buoys and satellite observations (www.odis.incois.gov.in). The wave forecasting system at INCOIS uses spectral wave models such as Simulating Waves Nearshore (SWAN), WAVEWATCH III (WWIII) and MIKE21 SW - which are nested /coupled with each other or with hydrodynamic models such as ADvanced Circulation Model (ADCIRC) to get the best possible forecasting capability. Although SWAN and WWIII are both third generation models, the former is preferred over the latter in coastal shallow waters, and vice versa for deep sea conditions. SWAN with shallow water physics packages, appropriate numerical schemes and high computational efficiency in coastal waters, makes it a preferred choice. The coastal wave forecasting system presented in this work uses an unstructured SWAN setup with the highest resolution near the coast, which is gradually relaxed to coarser resolutions offshore. The gradual decrease in spatial resolution from the coast to offshore is attained by the use of flexible unstructured mesh. This high resolution coastal setup is directly nested in WWIII to incorporate the wave energy contribution to the system by distant swells/remote forcing. This method eliminates the need for an extra structured SWAN model setup that is required in the conventional method, for feeding the WWIII boundary conditions to the unstructured SWAN grid. Separate east and west coast models are setup and the effect of integration of the two wave models viz., WWIII and SWAN is studied. The integrated SWAN+WWIII models for the east and west coasts are evaluated for normal as well as cyclonic situations with the help of observational data from waverider buoys. The results of the analysis show that the integration of the two models has a significant effect in filling up the energy in the low-frequency part of the wave energy spectra. Statistics of model errors before and after integration shows that the errors are significantly reduced after the integration, which in turn certifies the innovative method of integration used here. The integrated model setups for the east and west coasts are implemented in the High performance computing facility of Ministry of Earth Sciences to be used for operational wave forecasting at Indian National Centre for Ocean Information Services (INCOIS). |