Blog entry by Emelie Breunig
Surface drifters are like modern-day bottles containing messages: rather than carrying notes, they carry sensors and GPS, enabling us to trace the pathways of ocean currents in real time. They float on the sea’s surface, guided by an underwater sail called a drogue that ensures they drift with the currents in the top 15 metres of the ocean. During the cruise, we deployed 20 surface drifters in groups of three and four, each with a side length of 100 metres. Each set of three drifters formed the corners of a larger triangle with sides measuring 5 km. This pattern enabled the drifters to characterise changes in the surface current. If a current becomes wider or faster, the pattern of the drifters stretches or speeds up with it. As the weather forecast predicted short, high waves, the first 10 drifters were deployed from the ship. We threw drifters from the front and aft of the ship, then moved sideways to complete the triangle. This method required great nautical skill from the ship’s crew and good timing from the deployment team. For the second deployment, we used the Zodiac. Using a handheld GPS device for navigation, we deployed the drifters one after another at the designated positions. Once deployed, the surface drifters began their voyage and will report their position and the ocean surface temperature every 30 minutes for the next few months. Safe travels!
