REM2040-01
| Type | Oceanographic cruise |
|---|---|
| Set | This cruise is part of the set REM2040 |
| Ship | Thalia |
| Ship owner | Ifremer |
| Dates | 18/05/2015 - 24/05/2015 |
| Chief scientist(s) | DUDUYER Sarah , LURTON Xavier |
NAVIRES ET SYSTÈMES EMBARQUÉS Centre Ifremer Bretagne ZI Pointe du Diable CS 10070 29280 Plouzané 33 (0)2 98 22 40 40 |
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| DOI | 10.17600/15009700 |
| Objective | As well as determining the topography of seabeds, bathymetric multibeam echosounders can measure the degree of reflectivity of the seafloor (imaging). This reflectivity measurement is used to determine the type of seabed (sand, rock, seaweed, etc.). Historically, this measurement is not calibrated by level, so the relative change in level received as a function of the beam angle (angular reflectivity profile) or the ship's progress (changes in level indicating a modification in the type of bottom) is utilized. However, there is growing demand for an absolute measurement of the level of reflectivity. This would improve the determination of the type of seabed and make it more reliable. Another aspect is the emerging scientific need to be able to study the bottom and the water column simultaneously. Therefore multibeam echosounders are led to be able to supply both types of data, reinforcing the need for level calibration which is important for the analysis of water column data. The cruise continued the calibration phase of the EM 2040 multibeam echosounder begun in 2013 thanks to acquisitions on baseline zones, the deployment of a drop-down camera to validate the type of bottom by imagery and deployment of a grab to validate the bottom by sampling. The cruise also provided the opportunity to transfer the new sub-bottom profiling tow fish to the Genavir ground crew. The related project is "Acoustique sous-marine" (PJ0807). |
