Day 22: Monday 26 March
Sampling area: TOBI survey
Ship's position at midnight: 13 21.6376N, 44 54.91477W
Today I finished processing the raw sidescan sonar data from the southern part of our TOBI survey area using a software package called PRISM. In general the data were of good quality, although I had to make corrections for various things such as sea-surface reflections and ping drop-outs.
After the TOBI passes had been processed and re-located to their correct geographical position, I combined them together and created a digital mosaic of the sea-floor, which I then overlaid onto the bathymetry data. This allowed the senior scientists to have a virtual 3D roam about along the sea-floor, looking at areas of particular geological interest where we will later on take cores and dredges from.
Below is an example of the 3D map I created using Fledermaus software. The high back-scatter (white areas) indicate bare rock outcrops, and the low back-scatter (dark areas) are typical of sediments. This image shows a volcanic ridge several hundred metres high that runs from north to south at the very edge of our survey area.