Numerical modelling

An active area of research involves the development of mathematical models that, given the current state variables, forecast atmospheric and marine conditions at a later time.

Provided with the initial and boundary conditions, through complex computations, such dynamic models can output a number of fields such as air temperature, pressure, precipitation as well as sea temperature, salinity, current magnitude and direction and wave parameters.

The OMRG is constantly engaged in research related to the development of numerical forecasts including the ROSARIO Marine Forecast, the MARIA ETA atmospheric forecast, the Maria wave model and the MEDSLIK oil spill model.

The ROSARIO Marine Forecast

We run operationally a shelf scale forecasting system for the Malta Shelf Area. The ROSARIO marine forecast is provided at two resolutions: 1/64° and 1/96°. The Malta model run starts at 12:00 UTC of day 0 (the day prior to the release of the forecast) and provides 4 days of 3 hour averaged forecast fields centred at 1.5hr, 4.5hr, 7.5hr, 10.5hr, 13.5hr, 16.5hr, 19.5hr, 22.5hr of each day. Sea temperature, salinity and currents are outputted at various depth levels.

To validate the model, The ROSARIO64 Malta Shelf forecasted Sea Surface Temperature (SST) fields are compared with those derived from the Multi-Sensor Merged High-Resolution Sea Surface Temperature satellite observations over the Mediterranean Sea in 1/50° Geographical Grid. The comparison is made by constructing the difference map which plots the bias between the two realisations (SSTFor - SSTObs) at each pixel. The root mean square error between the two forecasted and observed SST calculated over all the sea pixels is further calculated at the successive cycles.

The MARIA Atmospheric Model

A system for operational numerical weather prediction has also been setup. The weather forecasts form part of the MARIA Malta atmospheric and wave forecasting system implemented as part of the Interreg IIIB MEDOCC project entitled Weatherrouting dans la Méditerranée (WERMED).

Two different forecast scales are generated. The first covers the whole of the Mediterranean Basin, whilst the second consists of a higher resolution map over the Central Mediterranean area including the area around the Maltese Islands. The forecast fields consist of air temperature at 2m from the sea surface, atmospheric pressure at mean sea level, wind direction and magnitude at 10m height above the sea, and precipitation.

The Mediterranean basin scale forecast is run on a daily basis, starting from 12h GMT of the current day and produces a 72-hour forecast with 6-hour outputs and a horizontal resolution in space of about 40km. The sub-regional higher resolution forecast also runs daily starting from 12hr GMT of the current daily and producing a 48-hour forecast with 3-hour outputs and a horizontal resolution of 1/6 degrees.

The MARIA Wave Forecast

The wave forecasting system uses surface wind from the MARIA ETA atmospheric model, and runs daily to produce a 72-hour forecast on a high-resolution grid (1/8º) over the Central Mediterranean. The model setup is based on the following run-time parameters: 30 frequencies (in the range from 0.041772 Hz to 0.66264); 24 directions (every 15 degree); 3 output grids; 4916 sea points; and 3-hour outputs. The main output parameters are: significant wave height; mean wave direction and frequency of total sea; wind sea and swell.

The forecasts generated by the above models are available to users through a user-friendly visual online portal, called PORTO, which allows the flexibility for choice of parameters and forecast times. The interface gives access to maps of the selected parameters, and offers a 2D view of sea state conditions in the Malta-Sicily Channel and south of the Maltese Islands.

Access the PORTO interface.

The MEDSLIK Oil Spill Model

Work on oil spill modeling has placed the OMRG in a high profile position within the international community in this field, and is also opening the way to our involvement in national contingency planning and networking with local agencies responsible for oil spill response. The Malta MEDSLIK Oil Spill Model provides a system to monitor oil slick movements in the Malta Channel, the Southern proximity of the islands as well as near the coastal areas. The model predicts the track of the spill from an open sea source down to nearshore/coastal area with precision. Besides assisting in oil spill response, MEDSLIK can also help in search-and-rescue operations. By taking into account the marine forecast for the corresponding days, and the initial position of an object at sea, it can estimate the position of that object after the specified number of hours.

Every year the OMRG participates in an oil recovery response simulation exercise organised by the Transport Malta, the European Maritime Safety Agency (EMSA) and the Regional Marine Pollution Emergency Response Centre (REMPEC). The exercise serves to demonstrate the benefits of using the Malta MEDSLIK oil spill model to predict the circumstances and trajectory of oil slicks in the vicinity of the Maltese Islands, and to anticipate the likely impacts in the coastal areas.


https://www.um.edu.mt/research/oceanographymalta/research/numerical-modelling/