Baywatch from space

What beach are you going to swim at this summer thanks to information provided by satellites?

As the summer draws near, in a few weeks we will be able to enjoy the bathing season in the Mediterranean Sea. What many people are unaware of is the fact that while we put our flip flops and towel in our beach bag, local and regional European governments are also getting ready for the season, setting up their monitoring processes based on Earth observation and oceanographic models.

Local and regional governments have recently begun to take measures to identify anomalies in water along their shores. Detecting anomalies that may affect both water quality and public health is essential for important sectors such as tourism and fishing. In addition, European Member States are required to accomplish with different European directives on the monitoring, assessment and management of bathing water quality.


Barcelona’s water transparency on 5th July 2013. Water was more transparent at the north of the city.

The immensity of the sea makes in-situ observation (i.e. getting samples far out at sea) impractical for large extensions of water. Doing this would require a huge human and monetary effort. The best alternative for the observation of big land and water extensions is using images taken by Earth Observation satellites. Using one or different images provided by satellites is a much better choice to determine the water state in the Mediterranean Sea (and in any other sea or ocean around the globe!).

At Star2Earth we have set up two high-performance computers dedicated exclusively to the processing of images obtained by NASA’s Aqua satellite. The main goal of these two computers is simple: to generate descriptive images of the water’s status for different parameters such as transparency, water temperature, the amount of chlorophyll present or the amount of suspended matter.

Star2Earth has been providing this service to the City of Barcelona during the past 3 bathing seasons, generating descriptive images of the state of the water along the city’s beaches.

Materia en suspensión durante actuaciones en el puerto

Different works performed in the Barcelona’s port caused an increment of the suspended matter nearby.

Another possibility offered by this system is to quickly view the impact certain that certain man-made actions undertaken on the coast can have on the marine environment. An example of this can be found in the satellite images obtained while construction work was carried out in the port of Barcelona in 2012. During this event we could detect a larger concentration of suspended matter in the area nearby the harbour (the intense green at the bottom of the picture shown here).

The images obtained from satellites are not only useful to coastal authorities. The citizen wanting to go for a swim can easily visualize useful information about the most transparent water or even where the water’s temperature is more pleasant.

Finally, one of the latest products produced by the Star2Earth business unit is based on the development of predictive models for the presence of jellyfish on the coast. The prediction is based on a discriminative model trained with data obtained from satellites. In particular, the model is based on machine learning algorithms. Once trained, the system provides a forecast of jellyfish arrival to the beaches several days in advance. Anyway, our achievements in the prediction of the presence of jellyfish in the Mediterranean beaches will be explained extensively by my colleague Javier Marín in his blog post coming in a few weeks.

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