Preface The expedition ARK XIX/3 with the German icebreaking RV ...

distribution agrees with the assumption that coarser sediments are deposited first as the
current runs down the channel and decreases in speed.
Since the penetration depth of the multicorer is mainly driven by the water content of the
sediments. The results of this study indicate that a higher backscatter grey level is caused
by a higher water content of the sediments. However, a distinct effect of the grain size
variation of the fine grained seafloor sediments on the backscatter grey level are not
evident in this investigation.
Shipborne Bathymetric surveys during the cruise ARKXIX/3a
Hydrosweep is capable of determining the mean sonic velocity that is required for
refraction correction of the slant sonar beams. This technique is known as cross fan
calibration. However, in order to apply a local water sonic velocity profile and to prevent
data gaps due to the calibration mode, CTD profiles of the water column recorded at
various locations during the cruise were processed and finally used during the data
acquisition with Hydrosweep.
The Hydrosweep system recorded data during the entire cruise and provides detailed
bathymetric data at the investigated locations. These locations are at the northernmost
Gollum Channel and at the Belgica mound province at the eastern slope of the Porcupine
Seabight, at the "Scarp" and "Hedge mounds" at the Porcupine Bank. Due to the slow
speed during the operation of "Victor 6000" a gain in data quality is expected.
During the bathymetric survey of the northernmost channel of the Gollum Channel system
70nm survey line have been covered. The aim of this survey is to extend the existing
Polarstern bathymetry and backscatter data of that area towards the mouth of the
channels in the west and to check whether changes of the backscatter data have
occurred with respect to the cruise ANTXVII/4. Due to the video system attached to the
MUC it became obvious that this channel is not active. This indicates comparable
backscatter data from the leg ANTXVII/4 and ARKXIX/3a.
Towards the end of the cruise a detailed survey of approximately 25nm was started
closed to the "Hedge mounds". In this location there are channel heads cutting the
continental margin. The data is appropriate for comparison with the Gollum channel
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