MONIZEE Monitoring Network

The Instituto HIdrográfico (IH) maintains a real-time monitoring capacity of the oceanographic conditions of the Portuguese coast through the MONIZEE infrastructure. At present time, this observation infrastructure has tide gauge stations, ondograph buoys, high-frequency coastal radars and multiparametric buoys, distributed throughout the mainland and national islands, integrated in the global monitoring networks.

MONIZEE collects fundamental measurements to monitor and understand both the transport mechanisms along the Portuguese continental margin and the processes of interaction between the coastal ocean and the deep ocean. Observations closer to shore provide essential measurements for understanding coastal circulation and processes in the area. This national infrastructure contributes to the European infrastructure network for coastal observations JERICO-RI.

The IH developed the data infrastructure, the Hidrográfico+ (H+), which allows exploring different types of geospatial data, including data acquired in MONIZEE, as well as downloading that same information that may be consulted on the geoportal https://geomar.hidrografico.pt/ or through the smartphone application.

National Maregraphic Network:

The national tide gauge network is made up of tide gauges measuring in real time with automatic transmission of data, in collaboration between the IH, DGT (Direção Geral do Território) and port administrations. It aims to collect, analyze and provide information on tides and mean sea levels for the most diverse purposes, namely: navigation safety, establishment of reference levels in hydrography, execution of coastal engineering projects, scientific research, fishing and recreational activities.

Ondograph Buoy Network

To measure the waves, the IH uses wave buoys, equipped with sensors that measure the three-dimensional acceleration of the movement of the free surface of the sea, which allows obtaining information regarding the height, direction and period of the waves. The buoys also have a sensor that allows measuring the temperature of the water at the surface. The acquired data is transmitted in real time, to a receiving station installed on land, which calculates the most representative parameters of sea agitation and retransmits the data to the IH, where it undergoes verification and quality controls to be later stored in a database. , disseminated and made available to the public.

Network of Multiparametric Buoys

This network is based on a typology of equipment capable of acquiring meteorological data (air temperature, atmospheric pressure, relative humidity, intensity, direction and gust of wind and solar radiation), and oceanographic data such as sea agitation, water temperature at various levels, environmental data (detection of hydrocarbons and underwater acoustics) and current measurements in the first 100m of the water column, as well as the possibility of placing other sensors in mooring. The data acquired by this equipment is sent via satellite communications to the IH, where it undergoes verification and quality control to also be stored in a database and disseminated to the public.

Some of the estimated parameters of sea agitation for both buoy networks are:

• Significant Height – Hs (m): Average of the highest third of the wave heights that were recorded during the observation period. Corresponds approximately to the visual assessment of wave heights.

• Maximum Height – Hmax (m): Maximum wave height recorded during the observation period;

• Average Period – Tz (s): Average of periods observed in the record. Represents the typical period of waves recorded during the observation period;

• Maximum Period – Tmax (s): Maximum wave period recorded during the observation period;

• Peak Period – Tp (s): Period corresponding to the frequency band with the maximum spectral density value. It is representative of the more energetic waves present in the record;

• Average Direction – THTP: Average direction corresponding to the peak period. It represents the direction of propagation of the most energetic waves. It is usually measured from the North, clockwise.

HF Radar Network

This monitoring network with high-frequency (HF) coastal radars aims at environmental monitoring and comprises the installation of two or more stations that make it possible to measure surface currents and sea agitation in an area up to 75 km from the coast. Its operation is based on measuring the Doppler variation and the intensity of the backscattered signal along each azimuth, every 5 degrees, providing a component of the vector. By joining the different components, the final vector of current intensity and direction is obtained. Using this system, it is possible to obtain vector maps of currents and sea waves in real time, monitor pollutant spots and feed assimilation models for forecasting.