Systematic oceanographic observations are important for validation and providing ocean data products. The OOS programme is designed to acquire in-situ surface, meteorological and oceanographic data on real-time basis from the seas around India. The parameters being measured under the programme are surface winds, waves, atmospheric pressure, temp., sea surface temperature, salinity, temperature profiles, dissolved oxygen, hydrocarbons, nutrients, radio-activity, sea-level etc. The state-of-the-art instruments like moored data buoys, drifting buoys, XBTs, current meter arrays and tide gauges are being deployed for measurements. In addition, validation of the satellite data would also be undertaken using the sea truth data generated under this programme.

5.1.1 National Data Buoy Programme

One of the important components of the OOS, is the National Data Buoy Programme (NDBP). The programme is being implemented by NDBP Centre at National Institute of Ocean Technology, Chennai.

Under this programme 15 moored buoys are to be acquired from M/S OCEANOR, Norway, with partial funding from Norwegian Agency for Development Cooperation (NORAD). Of these, 12 have already been deployed in both deep and shallow waters. Departmental ship ORV Sagar Kanya was utilised for this purpose. The first data buoy was deployed in Chennai Port on 21st August'97.

These Data buoys have sensors to measure wind speed and direction, atmospheric pressure, air temperature, sea temperature, current speed, current direction and wave parameters, etc. The buoys are equipped with global positioning system, beacon light and satellite transceiver. A few of these buoys are fitted with sensors to measure radio activity, turbidity, chlorophyll and dissolved oxygen in the ocean waters.

These buoys are also capable of powerful processing and data logging. The data transmission is through a two-way communication , presently utilising INMARSAT-C satellite terminals. A shore station to receive the data has been established at NIOT, Chennai, which also acts as a processing, analysing and storage centre. The data can also be disseminated to user agencies on real-time basis, wherever required.

5.1.2 Drifting Buoys and other Observing Systems

To augment the ocean observations, the department is also implementing a programme for deployment of other observing systems through the National Institute of Oceanography, Goa. About 48 drifting buoys will be deployed at periodical intervals over the 9th Plan period. The buoys so deployed will generate in-situ data, as well validate the satellite data. Additionally, three current meter arrays would be deployed along the equator at selected locations. For monitoring the upper ocean thermal structure in the Indian ocean about 900 XBT (Expendable Bathythermograph) probes would also be deployed along the Madras-Andaman-Calcutta and Bombay-Mauritius shipping corridors. Special campaigns for validation of data obtained from satellite would also be carried out.

During the year, nine drifting buoys with sensors for Sea Surface Temperature and barometric pressure,were deployed in the Indian ocean. The data is transmitted via ARGOS-Satellite and is made available to the India Meteorological Department and National Centre for Medium Range Weather Forecast (NCMRWF) on a real-time basis.

5.1.3 Sea Level Observation

The Sea Level Monitoring project envisages assessment of variations in the sea level due to climatic and other factors and impact of such variations on the Indian coastal belt. Under this project, 7 modern tide gauge stations have been established at Mumbai, Porbunder, Goa, Kochi, Chennai, Visakhapatnam and Kavaratti and three more tide gauges will be deployed at Machilipatnam, Paradip and Tuticorin. The data from these gauges is collected regularly and sent to the National Tide Data Centre at Survey of India, Dehradun for analysis.