Activities along the Indian coastline vary from traditional fishing to high-tech industries such as oil exploration. For efficient operations, critical information on sea state, such as wind waves, swell, currents, winds, and tides, is essential. Prior information on the state of the seas surrounding the Indian subcontinent is thus vital for smooth operational activities, not only for those venturing out to sea but also for those on the shore.
The Ocean State Forecast (OSF) Service provides information on ocean waves, winds, currents, water temperature, cyclone heat potential, etc. Issued forecasts contain information at 3-hour intervals for the next 5–10 days. These forecasts are generated by running a suite of numerical ocean models on high-performance computing systems to simulate ocean surface wave conditions and general circulation.
Real-time data obtained from various in-situ observation platforms, such as moored met-ocean buoys, wave rider buoys, Argo floats, XBTs and satellite-derived sea surface temperature, sea level, and significant wave height, are ingested into the numerical models with the help of advanced data assimilation techniques such as Ensemble Kalman Filters, 3D Variational Analysis, and Optimal Interpolation. This helps refine the model’s initial state and improves forecast accuracy.
The forecasts are customised using different nesting approaches within the model domains, ranging from coarse-resolution global setups that capture large-scale oceanic phenomena to fine-resolution coastal setups that resolve local coastal processes. This enables INCOIS to provide basin-scale ocean state forecasts, such as for the Indian Ocean, the Northern Indian Ocean, and the South China Sea, as well as state/UT-level coastal forecasts and location-specific forecasts near ports, harbours, and fish landing centres.
Users can take informed decisions based on the forecasted sea state conditions, saving life and property. There is thus an inherent economic benefit to the users of ocean state forecast information.
Recognising the role played by INCOIS in issuing forecasts for the region, the WMO Executive Council at its seventy-sixth session (EC-76) adopted the designation of ‘Regional Specialised Meteorological Centre’ (RSMC) to INCOIS for numerical ocean wave prediction and global numerical ocean prediction.
Users of this service include Fishermen, the Indian Navy, the Indian Coast Guard, merchant and passenger shipping agencies, offshore oil and gas exploration companies, regional users, research organizations, and other coastal communities. In addition to providing services to IO Rim countries, INCOIS extended its ocean forecast services to Pacific Island countries, RIMES member states, the Colombo security conclave, etc.
Parameters Description
Wind (m/s):
Wind can be defined as the horizontal speed of the wind, or movement of air, at a fixed height above the surface of the Earth. The units of this parameter are meters per second.
Significant Wave Height (m):
Significant wave height is defined as the average height of the highest one-third waves in a wave spectrum. Its value roughly approximates the visually observed wave height. Wave height represents the vertical distance between the wave crest and the wave trough. The unit of this parameter is meters.
Mean Wave Period (s):
The mean wave period is the mean of all wave periods in a wave spectrum. The wave period is the average time it takes for two consecutive wave crests, on the surface of the ocean/sea, to pass through a fixed point. The unit of this parameter is seconds.
Swell Height (m):
Swell height is the Significant wave height of swell waves. The unit of this parameter is meters.
Swell Period (s):
The mean period of swell waves is the swell period. The unit of this parameter is seconds.
Current Speed (m/s):
Current speed is the magnitude of the movement of water particles in a given direction. The units of this parameter are meters per second.
Sea Surface Temperature (°C):
Sea Surface Temperature is the temperature of sea water near the surface. The unit of this parameter is degree Celsius (°C) or kelvin (K).
Mixed Layer Depth (m):
Mixed layer depth is the thickness/depth of the ocean layer measured from the surface of the ocean. The mixed layer is the upper layer of the ocean where active air-sea exchanges create turbulence, resulting in a vertically uniform temperature and salinity. The unit of this parameter is meters.
D20 (m):
D20 is the depth of the 20-degree isotherm measured from the surface of the ocean. The unit of this parameter is meters.
