Dear interested reader, colleagues, families and friends,<\/em><\/p>\n \u00a0As you may have read in a previous blog entry, on-board the Maria S. Merian we are divided into two groups that work around the clock. There is the group of the petrologists and of the bathymetrists and we would like to give you an insight in the working routines of the different groups on this expedition. In today\u2019s blog entry, we would like to present you the work of the latter group – the bathymetrists.<\/em><\/p>\n Our team consists of six scientists, half of them \u201cseniors\u201d and the other half students. Each \u201csenior\u201d is paired with one student and together, this team is responsible for one of the three eight-hour-shifts of the day. Mapping the seafloor is not our sole task as bathymetrists. Together with the petrologists, we also have to select e.g., suitable locations for the deployment of the dredge in order to get the best possible samples.<\/em><\/p>\n But what exactly is bathymetry? The purpose of bathymetry is to compute depth-models that can then be used as a basis for maps of the seafloor. To acquire the necessary data, a transmitter attached under the keel of the vessel emits acoustic signals in a fan-shape that are reflected from the seafloor in different intensities, depending on the surface material. The harder the material (e.g. rock) the stronger is the reflected signal. As the seafloor is not a consistent, homogenous flat area, but a diverse landscape with features such as volcanoes, crevices, transform faults or large planes, there are differences in depth. Accordingly, the acoustic signals travel different amounts of time before they are detected and recorded by the receiver. From these differences in time the depth-model is calculated and displayed graphically. Since the velocity of sound is much faster in water than in air, up to 1500 m\/s, the time it takes the sound to travel from the vessel to the seafloor and back is in the order of seconds. After the acquisition of the information, the dataset is edited and cleaned before it can be used as a map in geographical information systems.<\/em><\/p>\n To determine possible sample locations the same principles are used. Apart from a bathymetric map, we use the differences in reflection intensities, also called backscatter signal, to make interpretations of the seafloor material for the selection of promising and interesting sites and subsequent deployment of the dredge (we come back to that later). In the visualization of the backscatter signal, areas with unsedimented rocks appear bright while areas covered under sediments are much darker. Since our aim is to get volcanic samples from the Bathymetrist Seamount Chain, we use this visualization to find the rocks of which these volcanoes consist \u2013 basalt. Our findings are then shared and discussed with the chief scientists and based on this, dredge locations are selected. However, the interpretation of bright areas in the backscatter signal, do not neccesarily indicate volcanic rocks, but can also point to other hard ground, consisting of e.g. manganese nodules, cobalt crusts or phosphorites. Therefore, the geological interpretation of every new bathymetric and backscatter map needs to be evaluated and ground truthed by seafloor sampling. But, that is science \u2013 to constantly re-evaluate and adapt interpretations and to develop new approaches.<\/em><\/p>\n \u00a0Martin Schade, Janto Sch\u00f6nberg <\/p>\n Die “alte” Karte unseres Arbeitsgebietes, die General Bathymetric Chart of the Ocean<\/em>\u00a0(GEBCO, links) basiert haupts\u00e4chlich auf Satellitendaten und hat eine Aufl\u00f6sung von maximal 800 m. W\u00e4hrend der Expedition MSM70 erreichen wir durchg\u00e4ngig eine Aufl\u00f6sung von 50 m. In den flachen Bereichen sogar bis zu 25 m! Das ist ein enormer Erkenntnisgewinn und die detaillierte Auswertung wird noch einige Zeit in Anspruch nehmen.<\/p>\n The “old” General Bathymetric Chart of the Ocean (GEBCO, left) is mainly based on\u00a0satellite\u00a0data with a spatial resolution of at most 800 m. During expedition MSM70 we achieve a constant resolution of 50 m. In the shallower regions we can even reach 25 m! This is an incredible gain in our knowledge of the seafloor and a detailed interpretation of the new maps will take some time.<\/i><\/p>\n","protected":false},"excerpt":{"rendered":" Liebe interessierte Leser, Kollegen, Familien und Freunde, wie Sie vielleicht schon aus einem fr\u00fcheren Blogeintrag erfahren haben, arbeiten wir an Bord der Maria S. Merian in zwei Gruppen rund um die Uhr. Aufgeteilt ist die wissenschaftliche Besatzung in die Petrologie-\u00a0 und Bathymetriegruppe. Wir m\u00f6chten Ihnen einen Einblick in den Arbeitsalltag der Gruppen und ihren Teams […]<\/p>\n","protected":false},"author":188,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-53","post","type-post","status-publish","format-standard","hentry","category-deep-sea"],"_links":{"self":[{"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/posts\/53","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/users\/188"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/comments?post=53"}],"version-history":[{"count":3,"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/posts\/53\/revisions"}],"predecessor-version":[{"id":58,"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/posts\/53\/revisions\/58"}],"wp:attachment":[{"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/media?parent=53"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/categories?post=53"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm70\/wp-json\/wp\/v2\/tags?post=53"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n<\/em>CAU<\/em><\/p>\n![\"\"](\"http:\/\/www.oceanblogs.org\/msm70\/wp-content\/uploads\/sites\/55\/2018\/01\/BridgeBathyteam.jpg\")
Um die gro\u00dffl\u00e4chige Meeresbodenvermessung der Expedition MSM70 so effektiv wie m\u00f6glich zu gestalten arbeiten unsere \u00a0Bathymetriker eng mit den Br\u00fcckenoffizieren zusammen. Hier beraten sich Sandra Schilling (2. Naut. Offizier, links), Dr. Morgane Le Saout und Martin Schade auf der Br\u00fccke.
\nTo \u00a0create the most effective survey patterns for the large scale mapping of expedition MSM70 it is important for the bathymetrists to work closely together with the bridge officers. Here Sandra Schilling (2nd naut. officer, left), Dr. Morgane Le Saout and Martin Schade discuss ship tracks on the bridge.\u00a0<\/em><\/p>\n![\"\"](\"http:\/\/www.oceanblogs.org\/msm70\/wp-content\/uploads\/sites\/55\/2018\/01\/GEBCO_vs_MSM70-OK.jpg\")
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