Integrated Coastal Observation Network (ICON) for real-time monitoring of sea-level, sea-state, and surface-meteorological data

National Institute of Oceanography (NIO) has established an Integrated Coastal Observation Network (ICON) of in-house designed and developed Internet-accessible real/near-real time reporting cellular based sea-level, sea-state, and surface meteorological (Met) stations at several locations on the Indian coasts & Islands (http://inet.nio.org). Subsurface pressure sensors and downward-looking microwave radars are incorporated in the sea-level station network. Sea-level, Met, and surface wave parameters are acquired using dedicated Linux based data loggers and uploaded to an Internet server at 5-, 10- and 30-min intervals, respectively with the use of GPRS cellular modems. The sensors and data loggers are powered from sealed lead acid batteries, which are charged through solar panels. The ICON provides graphical presentation of sea-level information (observed sea-level, predicted tide, residual sea-level); significant wave height and wave direction; and Met information (vector-averaged wind speed & direction, barometric pressure, atmospheric temperature, solar radiation, relative humidity, and rainfall). Installation of sea-level sensors free from the influence of stilling-wells and long narrow tubes renders the measurements ideal for tsunami and storm-surge studies by preventing waveform distortion and non-linearity of largeamplitude short-period signals. The network maintains accurate time-stamp of the dataset through Internet-time synchronization using network time protocol (NTP). Real-time reporting capability of ICON yields several benefits, such as (i) remote monitoring of proper working condition of individual stations; (ii) implementation of repair/maintenance in the shortest possible time, thereby minimizing break in the time-series data stream; (iii) periodic arrival of data stream from all stations at a single central server, thus yielding backup for the data from all the stations; (iv) access to the latest in-situ information; (v) allows possible use of data with automated real-time running numerical models for operational forecast. In contrast to the limited bandwidth provided by INSAT transmitters, coastal observations at high bandwidth at significantly low cost have become realizable using cellular GPRS network. The NIO-network allows, Internet based real/near-real time tracking and monitoring of sea-level, sea-state, and meteorological conditions along the Indian coasts and islands and from almost anywhere - an issue of considerable practical significance during natural disasters such as storm, storm-surge, and tsunami.