31st August 2020
COVID-19 might have delayed our travel plans. However, it did not stop ocean instruments from crossing our boarders. A drifter released 8 nautical miles west of Ġnejna on the 24th August 2020 09:00 UTC, is now about 38km south of Malta (Figure 1). So far, it has only been a five-day journey, but fifteen more months of data collection and real-time transmissions are expected.
Drifters are designed to float and to follow currents in the top 1m. Every hour, they establish satellite communication and transmit their location, the sea surface temperature, as well as other data collected by the onboard electronics. Their movements help to validate data measured by the CALYPSO HF Radar network that was recently extended by two new stations at Għar Lapsi in Malta and Ta’ Ċenċ in Gozo. These two additional sites allow sea surface currents in the south of the islands to be measured and mapped in real-time every hour (Figure 3). The project addresses the challenges of safer marine transportation, protection of human lives at sea, and safeguarding of marine and coastal resources from irreversible damages. CALYPSO South is also committed to put technological advancement and scientific endeavour at the service of humanitarian responses, reducing risks in sea faring, and protecting the marine environment. This project is led by Prof. Aldo Drago from the Physical Oceanography Research Group (Department of Geosciences) within the Faculty of Science of the University of Malta, and partially financed by the Interreg V-A Italia-Malta 2014-2020 programme.
In this mission, the drifter was released together with a float. Together, they are collecting important parameters in an area that is not very commonly observed (Figure 3). Floats are sophisticated equipment that can be programmed to autonomously go up and down the water column while measuring physical parameters including temperature and salinity. Once deployed, pumps inflate and deflate bladders to change the instrument’s buoyancy that in turn, allow it to ascend or descend. Once released, floats make their way to their set parking depth (in this case 250m) and drift. At specific time intervals, these dive to the bottom and gradually start going up at about 10 centimetres per second while taking measurements at a high frequency. At the surface, they wait until satellite communication is established, transfer the collected data, and repeat the cycle.
These experiments are being coordinated by Dr Adam Gauci, responsible for ocean observations of the Physical Oceanography Research Group. The Maritime Squadron of the Armed Forces of Malta (AFM) greatly assisted with the deployment of the instruments. This research is also being done in collaboration with the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS-Italy) that runs the ARGO-Italy programme. Such long-term monitoring systems provide a unique source of information to study the role of the oceans, and in this case, the Mediterranean Sea, on the climate system. This and similar missions make possible the collection of data required by operational ocean monitoring systems to improve and extended forecasts of the atmosphere and oceans.