On 25 July, at 1030 GMT in 50.80 N – 008 00 W, a sound velocity profilers comparison was conducted in 115 m depth. The purpose of this test was to determine the need of calibrating any of these instruments. Four different instruments, measuring sound speed and pressure (depth) were attached to a CTD rosette or to a MVP-200 cable end and they were dipped down to 97 m. There following table lists the instruments used.

Table 1. Instruments used during the profile comparison

The results of this test showed a clear match among the readings, although the sensor used in the MVP (AML Micro Smart) presented some differences. Most of these discrepancies were smaller than 0.2 m/s and therefore can be neglected. But some of them were notorious and they were located in the velocline depth range (depths between 25-35 m) . These values were up to 2 m/s , neglecting the depth sensors inaccuracies . Overall, the results were satisfactory and all sensors tested were considered valid for the survey without the need of calibration.