FMI’s first glider mission started in the Bothnian Sea

13.9.2016

Uivelo in the Tvärminne archipelago ready to dive for the mission (photo Pekka Alenius).
Uivelo in the Tvärminne archipelago ready to dive for the mission (photo Pekka Alenius).
Uivelo floats at surface position before an experiment in Lammi Pääjärvi. The rope behind the glider is connected to a surface buoy as a safety backup in the first test dive before each mission (photo Pekka Alenius).
Uivelo floats at surface position before an experiment in Lammi Pääjärvi. The rope behind the glider is connected to a surface buoy as a safety backup in the first test dive before each mission (photo Pekka Alenius).

After initial trials in UHEL field stations Tvärminne and Lammi, the first Finnish glider was launched for a multiweek expedition to study dynamics of water exchange between the Baltic Sea Proper and the Gulf of Bothnia.

The underwater glider "Uivelo” acquired by FMI with Academy of Finland FIRI2014 funding for the FINMARI consortium, was tested for the first time at Tvärminne Zoological Station in May 2016. Uivelo measured properties of the water column in Storfjärden and along a transect from the coast towards the open sea. Two Spanish glider specialists from SOCIB, Mallorca, assisted in preparations of the first missions and in installation of glider data processing software to be used in FMI. FMI has joined the international EGO (Everyone’s gliding observatories) network with Uivelo.

Uivelo is a Slocum G2 shallow water glider suitable for up to 200 m deep waters. The glider has several adjustable parameters affecting its gliding properties, which need to be carefully examined for the complicated, shallow and narrow fairways in the Finnish archipelago, before long haul marine operations. Additional tests were conducted in July/August in Lake Pääjärvi, Lammi Biological Station. Similar conditions can be encountered in river mouths in the Baltic Sea.

These preparations for multipurpose glider operations preceded the first long haul mission in the south-eastern Bothnian Sea, launched in early September 2016. The mission aims at charting the distribution and characteristics of water masses in relation to water exchange between the Baltic Sea Proper and the Gulf of Bothnia.

Uivelo has proceeded over 150 kilometres during the first week of the mission. It has measured a transect along the southern edge of the Bothnian Sea and is continuing along the deep trenches in the southern Bothnian Sea to northeast. Uivelo sends profiles roughly from one nautical mile distances during the mission and stores much more into its memory. Full data is recovered from the glider after the mission.