Blog entry by Sariaka Ramarherison with Ria Oelerich
Both gliders were deployed consecutively in a similar manner. The deployments were carried out from a small rubber boat to prevent damage to the microstructure probes, which require very careful and controlled handling. The following equipment was needed alongside a glider: a cart, a screwdriver, a mat and the glider’s wings. With the help of the ship’s crew, Ralf and Sariaka carefully used the cart to lower the gliders into the ocean for a first “trim dive”, a few tens of meters away from the Meteor. They remained close to the glider for about 20 minutes while it was diving at shallow depths, being monitored from the ship to make sure that it was ready to go on a longer mission. During deployment, constant communication with Ria — who operated the gliders from the Meteor — was essential to ensure the operation went smoothly. While the G1 glider fit rather comfortably in the rubber boat, the larger and heavier G3 glider proved more challenging to deploy. Nevertheless, deployment was successful and the gliders began their journey to uncover the secrets of the ocean.
The gliders soared the Flemish Cap area for a little less than two weeks, surfacing every 3-6 hours depending on the commanded dive behavior. Unfortunately, after just a few days the measured glider flight parameters revealed that the G1 was becoming heavier with each dive than it should have been. We thus had to recover it earlier than expected. The Meteor sailed towards the last GPS position provided by the glider, and thanks to everyone’s help, we were able to locate it precisely. Once it was in sight, we carried out a procedure similar to deployment, but in reverse. Despite the rocky waves, the recovery was successful and the G1 made it safely back on board.
As for the G3, it continued its mission over the course of two full weeks. The data it sampled shows clear oceanographic structures, and promises an exciting analysis. Instead of the front that we had originally planned to observe, the glider crossed an eddy — a rotating ring of water induced by a turbulent flow. The eddy also presented interesting frontal structures.
For the recovery of the G3, using the rubber boat was not possible due to the sea state. Therefore, we had to recover it from the ship with a rescue net.
Back on board, the gliders were cleaned with fresh water, and the data was retrieved from the gliders and the Microrider for a first quality check.
While challenging, deploying gliders is a very rewarding experience! The unexpected is bound to happen, and when at sea, solutions must be found on board, which often leads to surprising yet robust fixes. Thus, through this expedition, the glider team learned one valuable lesson: patience is key.
