MS MERIAN 20-1
„Floating University“ MSM 20-1 started
On the 6th of January the RV MARIA S. MERIAN departured from Cape Town. On board are 12 students from different universities in Germany and Namibia, which will be taught by three scientists from the MARUM and GEOMAR in acquiring and processing of hydro-acoustic data sets.
The students will report in this Ship´s log on the work and life on board the research vessel.
You have questions to the MARUM scientists on board the research vessels? Just send an e-mail to:
Saturday, January 14, 2012
The barbeque last night was great, and went on late into the night for those that were lucky enough not to have shifts at the time. For those that did, work had to come as a priority. Mapping of the newly discovered seafloor structure continued at full steam throughout the whole night. Students on watch directed the ship, running lines next to each other, in order to acquire full spatial data with the E1002 system. The velocity of the ship was thereby reduced from 13 to 8 knots. The morning greeted us with grey skies and strong winds, however this did not delay our mapping course. The ship finally stopped at 10:07 UTC, when the 8th velocity profile was taken at 20° 47.093’ S and 12° 50.259’ E. Reliable and true velocity profile corrections are very important to us, since the bathymetric map of the region is scientifically very interesting and we want to have the best quality possible. The sun peeked out of the clouds to reward us for a job well done, and we used this moment to snap a quick photo of the entire scientific crew of the Merian. As you can probably see on the photo, despite the sun’s appearance, we were very well ventilated by the wind while posing for the photo. After the profile taking, we set sail again.
Scientific crew on the working deck of RV Maria S. Merian (Photo: M. Maggulli).
Afterwards we decided to end the canyon hunting and headed southwards towards Walvis Bay and especially towards the “foot print”-like structure. Exploring such features with our systems is not only of service to our scientific interests, but will also contribute to enriching the GEBCO bathymetric map set, which is used by scientists all over the world, since our exploration data will be shared with the scientific community following the principle of open and collaborative science making. We reached the vicinity of the structure at 16:50 UTC and turned westwards to get some more information about it using EM 1002 and Atlas Parasound on it. Unfortunately, after about an hour of searching, no trace of the structure was seen. GEBCO maps, on which we base our searches sometimes have artifacts, which have a 50/50 chance of being real. Unlike our “canyon” structure from yesterday, today the glass proved to be half empty. Despite that, in science a negative result is still a result, and we are happy to have finally solved the question of the existence of Manitou’s shoe, as it is called unofficially on board.
Since this is the last day of our cruise, we are all quite busy; even more so than the normally busy pace of scientific life on board. Data needs to be backed up reliably, the Parasound profiles from last night need to be processed, multibeam data from the new device needs to be scrutinized, evaluated and fixed, examples and screenshots of interesting seafloor features need to be presented to the group, and of course, a cruise report needs to be written. As it is looking, we will have a full night of work ahead of us before reaching the port of Walvis Bay.
Therefore, we would like to say “good bye” to all our readers and thank captain Ralf Schmidt and the crew of RV Merian for their professional support and for the pleasant atmosphere on board, which makes the “Floating University” very successful.
Eva, Milen and the team of the “Floating University”
Friday, January 13, 2012
The end of our cruise seems to approach rather fast now. Since the last OBS has been recovered yesterday afternoon, the Floating University is the primary user of the vessel for the last days. Today’s first station was at 11:00 am, close to the Namibian coast at 20° 52.18’ S and 12° 10.63’ E. Figure below shows a bathymetric map of the region, based on satellite data. Close to the coastline within the shelf region, there are two interesting features: One appears to be a canyon while the other looks like a giant footprint on the seafloor.
To figure out whether these features are real or artifacts, the echosounder EM1002 was installed and used for multibeam mapping of the seafloor. Afterwards we went “canyon hunting”: the ship had to go several times over the canyon feature to see whether we could trace it with the multibeam echosounder and Parasound systems.
In order to correct the multibeam data we took another sound velocity profile. This was the first time that one of the students was in charge of the profile. Luckily it worked out well and we learned the proper way to communicate with the ship’s crew during station work.
Map of research area for the last few days. Two interesting features on the seafloor are investigated. One of them could be a canyon; the other resembles a giant “footprint” that may be related to the mountain lying directly opposite the feature onshore Namibia.
We took off from the station at 11:45 am, and after a few technical problems in the beginning we were able to discover a channel-like depression in the Parasound and the EM1002. Surprisingly, the structure runs from North to South instead from East to West like the one we were looking for (screenshot 1 and 2).
Where we had expected a canyon-like feature, we did not find one, however the structure that has been observed in figure on the right top looks like a step in the seafloor. The eastern part of the feature looks similar to a head-wall structure caused by submarine landslides (screenshot 3). The interesting thing about it is that the location of the feature is quite unusual. It is located in the middle of the shelf and the shelf break is therefore rather far away from the structure.
To map the whole feature we were doing a survey of parallel lines. As the mapping continues during the night the students on watch will be in charge of setting the course of the ship.
In the Parasound data we observed another interesting structure right beside the channel-like depression that appeared to be a sand body (screenshot 4).
Since there are so many open questions concerning the discovered structures, we will be mapping in this region until tomorrow. Hopefully, we will still have some time left afterwards to investigate the footprint structure.
In the afternoon it was possible for us to take a guided tour through the engine rooms. The most fascinating fact for us was that it is actually possible to steer the ship from the engine room. We also learned that the ship has two separate engines that can be operated independently in case of a failure.
The day was nicely rounded up by a barbecue and a little party afterwards.
Greetings from barbecue party,
Justine and Daniela
Screenshot 1 : Screenshot from parasound acquisition window while crossing the observed channel-like depression.
Screenshot 2 : Screenshot from multibeam EM1002 after several crossings of the observed feature. The blue coloured region represents the depression.
Screenshot 3 : Screenshot from multibeam EM1002 of the headwall-like feature we discovered in the area where we expected the canyon.
Screenshot 4 : Screenshot SLF parasound acquisition window shortly after crossing the depression. The observed structure beside the depression appears to be a sandbank.
Thursday, January 12, 2012
Since today the last two ocean-bottom seismometer (OBS) have been recovered successfully, all crew members and scientists feel pretty relaxt. Such a smooth operation during all twelve stations had not have been really expected from the beginning on. The first OBS, located within the Angola Basin in a huge water depth of about 5100 meters was recovered at 6 am. Also the second OBS situated on the Walvis Ridge was collected without any problems at 4 pm. Surprisingly, as a kind of reward for the recovery and the precise work of the whole team , the OBS provided some deepwater cooled softdrinks (4°C), which were taken gratefully by everyone due to the sunny day over the south-eastern Atlantic Ocean.
Satisfied OSB Team after recovering the last OBS from the seafloor.
Furthermore the velocity- and temperature measurement number 6 was performed with the sound velocity probe during the first OBS Station down to a depth of 1800 meters.
Also the Floating University celebrated this day due to the fact that it “conquered” the vessel – at least in purpose of controlling all scientific research. The hydroacoustic systems (Parasound, Echolot) now will run uninterruptedly until reaching the harbour of Walvis Bay. Today one of these systems, the Atlas Parasound P70, is described in the following in order to provide some information for the student´s grandparents and Paul´s children!
Measurements with the Parasound Sedimentecholot are based on the so called “parametric effect”, which means that two primary high frequency signals (PHF) of 18 kHz and 22 kHz are transmitted by the system producing one secondary low frequency signal (SLF) of 4 kHz. The main advantages of this method are the high resolution as well as a relatively high penetration depth of the sea floor and its subsurface. An example is illustrated in the figure on right top.
This section of a profile taken on the 10th of January 2012 along the southern flank of the Walvis Ridge illuminates very clearly the upper 100 meters of wavy sediment structures, which can be observed in a water depth of approximately 1450 meters. These features give evidence for paleoceanographic variabilities in this environment, e. g. the direction of ocean currents.
Irena and Andre
Wednesday, January 11, 2012
For the first time since we have reached Namibian waters, this has been a sunny day. We are still at the Walvis Ridge (18° 6.54 ‘S, 10° 59.00 ‘E).
The day started with work as usual in our shift system (group 1: 0-4 am/0-4 pm; group 2: 4-8 am/4-8 pm and group 3: 8-12 am/8-12 pm). Today three OBSs were recovered over the day with the first OBS station at 2:29 am (UTC). This first station brought up a small visitor (photo top right) from the deep world of the sea bottom (depth around 2400 meter).
Over the last days we had many different lectures on data processing (e.g. introduction to Linux, working with sound velocity profiles, replaying of the parasound data with the ATLAS Parastore software). One of the main focuses for today was working with Linux based software GMT (Generic Mapping Tool) and the interpretation of sound velocity profiles.
Students of the ‘Floating University’ working together in the data processing room.
(Foto: Gesa Barkawitz)
By now five velocity profiles have been taken. The first was a test in South African waters. The other four profiles are from Namibian waters. The sound velocity profile (SVP) information is especially important for the multibeam echosounder’s (MBES) accuracy.
The SVPs can be used in two different ways. Directly, during data acquisition, when loading the SVP into the MBES acquisition software SIS. Second, for correcting the data during post processing.
With reference to the SVP graph shown on the right, one can see two examples from our cruise. Profile 1, measured near Cape Town in South African waters (17.4309/-32.6684) and profile 3 (10.7780/-19.8904) measured in Namibian waters.
It is obvious that most changes appear in the first 200 meters of the water column, mainly due to temperature changes. The dashed lines (Profile 2/4) show an extract of the LEVITUS Database, approximately at the same positions as the measured profiles. Although there are differences, they show nearly the same trend as the profile recorded during this cruise.
Due to the fact that wrong sound velocity profiles produce channel like structures on the seafloor, it is very important to use the measured profiles. In the figure below you can see the difference between multibeam data being processed with a wrong sound velocity profile (left) and the same data being processed with the performed velocity measurement (right).
Sunny greetings from the Walvis Ridge, Monika and Gesa
Tuesday, January 10, 2012
For today the recovery of another four ocean-bottom seismometer (OBS) was on the schedule. These were located along a track across the Walvis Ridge. Therefore the depth from where the instruments rose up varied between 1257 and 3680 meter. After locating by triangulation, the students helped to watch out for the ocean-bottom seismometers on the bearing deck. All instruments were recovered safely. Between the OBS stations, Data was acquired with the Atlas Parasound P70 and the singlebeam echosounder EA600. Due to the strong relieve of the Walvis Ridge, we measured a great variability in sedimentary structures.
Furthermore the 4th velocity- and temperature profile was logged with a Sound Velocity Tool (SVT) and presented in a diagram with the former data. There was a clear difference between the shallow water (230 meter) profile collected off South Africa and the deep water (1000-1800 meter) profiles collecting off Namibia regarding sound velocity and temperature.
Processing of the bathymetric data was continued, so we could start the velocity correction in the evening and created the first pictures of the sea bottom using the processed data.
Finally we had the opportunity to be creative and each group designed a cruise logo. Here you can see the winner logo and the other proposals:
The day ended with a fantastic sun rise and the recovery of the OBS “FC St. Pauli“.
Best wishes from the southern hemisphere,
Janina and Sofia
Monday, January 9, 2012
In the early morning at around 03:30 AM we reached the first station at Walvis Ridge (21°47.809S, 9°2,000E), where an ocean-bottom seismometer (OBS) had been deployed one year ago. The OBS is equipped with one hydrophone and one geophone detecting seismic waves. Usually, the OBS is located by sending signals from three different points. To avoid interruptions the hydro acoustic systems are shut down. As the OBS did not react on the third call, the chief scientist decided to trigger the acoustic release already at the first triangulation point. With this the anchor of the OBS is released and the device rises to the sea surface with a velocity of about 1.2 m/s. There it can be located by the installed radio station, flashlight or flag. At 04:45 AM the first OBS was recovered from the calm sea after ascending from 4000 m water depth. While waiting for the OBS to show up there was enough time for taking another sound velocity profile for later corrections of the hydro acoustic data.
The ocean-bottom seismometer (OBS) is recovered
Around 12:20 PM we reached the second OBS station, and this time the triangulation was successful. Two hours later the instrument was recovered. During the waiting time, some students who are not familiar with Linux got a crash course in the basics of some terminal commands of the OS, and also got a first look in data processing of the multibeam data with MBSystem. Thus, we could start processing the first multibeam data from offshore South Africa.
Best regards from Walvis Ridge,
Johanna and Timo
Friday, January 6th, till Sunday, January 8th, 2012
Heading towards the south most of us arrived in Cape Town (33 37,227 S/ 18 07,082 E) at the 4th and 5th of January 2012 looking forward to participate the MARIA S. MERIAN cruise MSM20-1 (WALPASS). Even those expecting 30°C plus were surprised about the heat in Cape Town. While using the 5th of January for preparations in the calm harbor we left the city according to the schedule 08:30 AM on the 6th of January, exactly a 100 years after Alfred Wegener presented his ideas about the “continental drift” at a conference in Frankfurt/Main. It was a nice, sunny but windy day (Beaufort 5-6).
The main goal of leg MSM20-1 is the recovery of twelve broadband ocean-bottom seismometers which were deployed during MSM17-2 in January 2011 around the intersection of the Walvis Ridge with the continental margin. This project is funded by the German Research Foundation within the SAMPLE priority program. Detailed information can be found (Link zum Fahrtenheft, Leitstelle). Moreover this cruise is used to train 12 students from Germany and Namibia in shipborne hydroacoustic techniques within a so called “floating university” powered by the University of Bremen/MARUM and GEOMAR (Kiel).
Due to a permit of the South African authority we were able to start our lessons right after leaving the port with the acquisition of multibeam and subbottom profiling. Beside the introductions to the hydroacoustic systems, the first days have been used to get familiar with live on board, watching in shifts and working on a moving platform. Part of this familiarization was an exciting security training (see picture).
Security training on board RV Maria S. Merina
(Photo: P. Wintersteller)
For improving the bathymetric measurements, we took also a first sound velocity profile on the 6th of January for later correction of the multibeam data (32 25.860 S / 17 14.300 E). The 7th of January we used for further education like the principles of multibeam echosounding and parametric subbottom profiling. The day was rounded up by an evening invitation of the cook celebrating his birthday. Unfortunately, we had a breakdown of the echosounder EM120 during the night of th 7th to 8th, however we are optimistic that the crew can solve the problem for a successful continuing of our project.
During the next days the students will continue this blog.
With best regards from the South Atlantik,
Paul, Tilmann and Willi