API src

Found 18 results.

Other language confidence: 0.6837586152314934

Bundesamt für Naturschutz: Erfassungsdesign des aktuellen marinen Wirbeltiermonitorings in der deutschen AWZ (WFS)

Die Vorkommen von Schweinswalen und wichtiger Rast- und Zugvorkommen von Seevögeln in den küstenfernen Meeresgebieten werden von Flugzeugen aus entlang von Flugtransekten ermittelt. Das BfN führt flugzeuggestützte digitale Erfassungen von Meeressäugetieren und Seevögeln in Nord- und Ostsee durch. Diese werden zum Teil zur Evaluierung der so gewonnenen Daten noch durch analoge Flüge begleitet und dienen der Berechnung der Verbreitung, Abundanzen und Trends für die Bewertung des Zustands von Seevögeln und Meeressäugetieren (hauptsächlich Schweinswalen) in der deutschen Nord- und Ostsee. Je nach Jahreszeit und/oder Ort stehen entweder Meeressäugetiere oder Seevögel im Fokus der Erfassungen. Basierend auf den Erfahrungen aus dem langjährigen Wirbeltiermonitoring wurden die Seegebiete der deutschen Nord- und Ostsee in für die Monitoringansprüche fachlich sinnvolle Untersuchungsgebiete unterteilt und diese Gebiete mit spezifischen Transektdesigns ausgestattet. In Teilbereichen des Vogelschutzgebiets „Östliche Deutsche Bucht“ aber auch anderen für Seevögel relevante Gebiete in der deutschen Nordsee werden diese Erfassungen verdichtet. Zusätzlich werden Teilgebiete der Nordsee mit Schwerpunkt auf die überwinternden Seevögel jeweils im Winter erfasst. In der Ostsee wird das Vogelschutzgebiet „Pommersche Bucht“ im Bereich der Oderbank mit Schwerpunkt auf die überwinternden Seevögel jeweils im Winter erfasst. Zusätzlich wird in der Ostsee ein kontinuierliches, ganzjähriges POD-Monitoring betrieben. Diese erfassen in Gebieten mit geringen Populationsdichten die Wale mit Hilfe akustischer Detektionsgeräte (PODs, Cetacean POrpoise Detector), die dauerhaft unter der Wasseroberfläche installiert werden. Im Rahmen dieser Langzeitdatenerhebung werden vom BfN POD Messpositionen in den FFH Schutzgebieten und angrenzenden Gewässern betrieben. Die gewonnenen Daten werden hinsichtlich des zeitlichen und räumlichen Vorkommens von Schweinswalen und derer akustischer Verhaltensweisen untersucht.

Bundesamt für Naturschutz: Erfassungsdesign des aktuellen marinen Wirbeltiermonitorings in der deutschen AWZ (WMS)

Die Vorkommen von Schweinswalen und wichtiger Rast- und Zugvorkommen von Seevögeln in den küstenfernen Meeresgebieten werden von Flugzeugen aus entlang von Flugtransekten ermittelt. Das BfN führt flugzeuggestützte digitale Erfassungen von Meeressäugetieren und Seevögeln in Nord- und Ostsee durch. Diese werden zum Teil zur Evaluierung der so gewonnenen Daten noch durch analoge Flüge begleitet und dienen der Berechnung der Verbreitung, Abundanzen und Trends für die Bewertung des Zustands von Seevögeln und Meeressäugetieren (hauptsächlich Schweinswalen) in der deutschen Nord- und Ostsee. Je nach Jahreszeit und/oder Ort stehen entweder Meeressäugetiere oder Seevögel im Fokus der Erfassungen. Basierend auf den Erfahrungen aus dem langjährigen Wirbeltiermonitoring wurden die Seegebiete der deutschen Nord- und Ostsee in für die Monitoringansprüche fachlich sinnvolle Untersuchungsgebiete unterteilt und diese Gebiete mit spezifischen Transektdesigns ausgestattet. In Teilbereichen des Vogelschutzgebiets „Östliche Deutsche Bucht“ aber auch anderen für Seevögel relevante Gebiete in der deutschen Nordsee werden diese Erfassungen verdichtet. Zusätzlich werden Teilgebiete der Nordsee mit Schwerpunkt auf die überwinternden Seevögel jeweils im Winter erfasst. In der Ostsee wird das Vogelschutzgebiet „Pommersche Bucht“ im Bereich der Oderbank mit Schwerpunkt auf die überwinternden Seevögel jeweils im Winter erfasst. Zusätzlich wird in der Ostsee ein kontinuierliches, ganzjähriges POD-Monitoring betrieben. Diese erfassen in Gebieten mit geringen Populationsdichten die Wale mit Hilfe akustischer Detektionsgeräte (PODs, Cetacean POrpoise Detector), die dauerhaft unter der Wasseroberfläche installiert werden. Im Rahmen dieser Langzeitdatenerhebung werden vom BfN POD Messpositionen in den FFH Schutzgebieten und angrenzenden Gewässern betrieben. Die gewonnenen Daten werden hinsichtlich des zeitlichen und räumlichen Vorkommens von Schweinswalen und derer akustischer Verhaltensweisen untersucht.

CPOD Station

In der Ostsee wird durch das BfN ein kontinuierliches, ganzjähriges POD-Monitoring betrieben. Diese erfassen in Gebieten mit geringen Populationsdichten die Ortungslaute von Schweinswalen mit Hilfe akustischer Detektionsgeräte (PODs, POrpoise Detector), die dauerhaft unter der Wasseroberfläche installiert werden. Im Rahmen dieser Langzeitdatenerhebung werden vom BfN POD Messpositionen in den FFH Schutzgebieten und angrenzenden Gewässern betrieben. Die gewonnenen Daten werden hinsichtlich des zeitlichen und räumlichen Vorkommens von Schweinswalen und derer akustischer Verhaltensweisen untersucht.

Integrated observations from NEAR shore sourcES of Tsunamis: towards an early warning system (NEAREST)

The NEARESTproject (Integrated observations from NEAR shore sourcES of Tsunamis:  towards an early warning system) aimed at the identification and characterization of potential near-shore sources of tsunamis in the Gulf of Cadiz. This area is well known from the catastrophic earthquake and tsunami that destroyed Lisbon and several other places mainly along the EastAtlantic coast on November 1st, 1755. One of the project's work packages dealed with monitoring of recent seismic activity in the Gulf of Cadiz area. For this purpose 24 broadband ocean-bottom seismometers (OBS) from the German DEPAS instrument pool were deployed for 11 months in addition to the GEOSTAR multi-parameter deep-sea observatory and two temporary land stations in Portugal. The GEOSTAR observatory and the 24 OBS were deployed and recovered during two expeditions with RV Urania in 2007 and 2008. The OBSs consist of  three‐component Guralp CMG‐40T‐OBS seismometers and HighTech HTI‐04‐PCA/ULF hydrophones. A wide range of signals was recorded, ncluding teleseismic, regional and local earthquakes, and low‐frequency (∼20 Hz) vocalization of fin whales.  The GEOSTAR  observatory was again deployed between 2009 and 2011. The Portuguese temporary land station PDRG was additionally recording during the NEAREST project. Originally, the position of recovery on deck was taken to calculate the mean coordinate of the OBS at depth from deployment and recovery coordinates. In most cases the difference in coordinates between deployment and recovery is very small (table 3 and 4 in Carrara et al., 2008). For two stations, the location at the seafloor could be measured by triangulation (Carrara et al., 2008). Due to experience of other experiments over the years, we finally suggest to use the deployment coordinates as the station coordinates for all stations that could not be tri-angulated. The clocks were synchronized with GPS time before the deployment and if possible again after the recovery. Unfortunately, most of the batteries were empty at the end of the recording period. That either made it impossible to realize the second synchronisation (skew time measurement) or in some case also caused erroneous synchronisations. Therefore, the internal clock drift was estimated by ambient noise analysis (Corela, 2014). The internal clock drifts were corrected using a linear interpolation method. Generally, the data quality is very good, especially for the intended study of local and regional earthquakes. Studies relying on wideband seismological recordings can also be carried out. The sensor package and noise conditions hamper the use for broadband and very broadband applications. Unfortunately, also not all channels operated properly, therefore hampering the use of multi-component methods for the relevant stations. We thank the captain E. Gentile, crew, G. Carrara, and all participants of the R/V URANIA expeditions in 2007 and 2008. We are grateful to all people and institutions involved in the NEAREST project. Waveform data is available from the GEOFON data centre, under network code 9H.

BEAR ISLAND: DEPAS ocean-bottom seismometer operations in the Fram Strait in 2007-2008

BEAR ISLAND (The Dynamic Continental Margin Between the Mid-Atlantic-Ridge System (Mohns Ridge, Knipovich Ridge) and the Bear Island Region) is an interdisciplinary project exploring the stress conditions and sources, and the dynamics and deformation characteristics of the continental margin between the Mid-Atlantic Ridge and Bear Island from its top sedimentary cover to its imprint in the upper mantle. In this region the margin includes an extremely thick sedimentary wedge and steep slopes, with at least one major paleo-fracture zone cutting through the wedge. Recent studies in this area indicate very low seismic velocities in the lithosphere and the stress field undergoes an extensional-compressional transition. It is therefore of particular interest to understand the structural architecture, the stress and the dynamics of the whole region because of its natural hazard exposure and the processes involved in the formation of the margin and the opening of the North Atlantic. To achieve this, deep seismic sounding data, as well as records from temporary broadband installations, supplementary to data from existing seismic stations in the region were collected. A key element of the project was the operation of a long-term network of broadband ocean-bottom seismometers (OBS). Additionally, two new broadband seismometers and a small temporary seismic array with 13 sensors were operated. Active seismic refraction/reflection experiments were conducted along two profiles crossing the region and recorded with additional short period OBSs and land stations. Twelve broadband ocean-bottom seismometers (OBS) from the German Instrument Pool of Amphibian Seismology (DEPAS) were deployed as part of this network with RV Horyzont II in September 2007. They were distributed on the Barents shelf, the slope and the deep sea near the Mid-Atlantic Ridge. Nine instruments could be recovered in August 2008 with RV Horyzont II. One instrument was fished before, one was destroyed during recovery and one got lost. Seven stations recorded data for the full deployment period; two stations have no skew value. The time correction for these stations was estimated by noise cross-correlations. Based on previous experiments, the accuracy of the positions is estimated to 500 m. Waveform data is available from the GEOFON data centre, under network code 9C.

Archimedes

This dataset includes five stations of an Ocean Bottom Seismometer (OBS) experiment conducted at the southern end of the Fonualei Rift and Spreading Center in the Lau Basin, southwestern Pacific. The OBS recorded continuously for 32-days on 4 components, including a hydrophone and a 3-component 4.5 Hz geophone. The experiment was conducted during RV Sonne cruise SO267, project ARCHIMEDES I.

WAVEOBS

The WAVEOBS project was established with three primary goals; to get a better fundamental understanding of microseism sources in the north-east Atlantic near Ireland; to investigate the use of ocean generated microseisms as real time ocean wave height data; and to investigate their use as a climate proxy. Waveform data is available from the GEOFON data centre, under network code 4V, and is fully open.

GAKKELDEEP: DEPAS ocean-bottom seismometer operations at the Gakkel Ridge in 2018-2019

“Gakkel Deep is a pilot project that installed a network of four broadband ocean bottom seismometers (OBS) near Gakkel Deep, the deepest depression in the Arctic Ocean, at the eastern end of the ultraslow spreading Gakkel Ridge. The area is covered year-round by sea ice. In order to enable a safe recovery of the OBS in a sea ice covered ocean, the OBS were modified to include a positioning system that allows to track the instruments at meter accuracy during descent and ascent and when stuck beneath ice floes. This pilot studied aimed at testing the recovery procedure of the OBS, checking the performance of the modified instrument design, getting an overview of ambient seismic noise at the bottom of the Arctic Ocean and at contributing to a better understanding of the origin of the Gakkel Deep depression with more than 3000 m of topography. The network is shaped as a rectangle with 8 km and 10 km side length and is centered at about 82°N 119.5°E at water depths between 3600 m and 4100 m. It is positioned slightly to the east of the present plate boundary in an area with volcanic structures. Instruments from the German Instrument Pool of Amphibian Seismology (DEPAS) were deployed during RV Polarstern cruise PS115/2 on September 15, 2018. Instrument recovery was completed during RV Polarstern cruise PS122/1 on September 27, 2019. The data set contains about 377 days of continuous records at 250 Hz sample rate. The station locations were determined with Ultra Short Baseline (USBL) ranging, the accuracy is approx. 10 m. The non-linear clock drift was determined by means of noise cross-correlations and applied to the data set. Waveform data are available from the GEOFON data centre.

Project BRAVOSEIS: DEPAS ocean-bottom seismometer operations in the Bransfield Strait in 2019-2020

BRAVOSEIS (Bransfield Volcano Seismology) is an interdisciplinary project exploring volcanism in the Bransfield back-arc basin, Antarctica. Partners from Spain (amongst others UGR, project leader), Germany (AWI, GFZ) and the US (CUNY, UW, WHOI) performed various geophysical onshore and offshore measurements in the Antarctis seasons 2017-2018, 2018-2019 and 2019-2020. A key element of the project was the operation of a large long-term amphibious network of broadband seismometer in the Bransfield Strait, on the adjoining South Shetland Islands, and on the Antarctic Peninsula. Nine broadband ocean-bottom seismometer (OBS) from the German Instrument Pool of Amphibian Seismology (DEPAS) were deployed as part of this network with RV Sarmiento de Gamboa in January 2019 (cruise SDG076). They were distributed along the entire basin, one station supplemented a dense array of short-period OBS around the Orca seamount. Eight instruments could be recovered in February 2020 with RV Hespérides (cruise HE0188), one OBS is still missing. All stations recorded data for the full deployment period. Unfortunately, the clock drift of all stations turned out to be non-linear, a skew measurement was possible for four stations only. The clock drift was corrected by means of noise cross-correlations. Based on previous experiments, the accuracy of the positions is estimated to 500 m. Waveform data is available from the GEOFON data centre, under network code ZX.

Darss Sill shallow water OBS Test

For broadband ocean bottom seismometer (OBS) data, external noise is typically more pronounced than on seismometers installed onshore. However, the sources of this external noise are only partly understood. In particular, the impact the instrument design (form-factor of the floatation, pressure vessel, hight-to-width ratio) has on the amplitude of external noise is not fully understood. As a developer of OBS systems, K.U.M. Kiel GmbH has deployed two different types of OBS systems side-by-side for a period of 77 days. Both instruments included the same seismic sensor, a Nanometrics Trillium Compact 120 OBS. Station LOBS was a K.U.M. LOBSTER-type instrument carrier (https://jlsrf.org/index.php/lsf/article/view/165) which is the main instrument type in the DEPAS pool “German instrument pool for amphibian seismology”(https://www.awi.de/en/science/geosciences/geophysics/methods-and-tools/ocean-bottom-seismometer/depas.html). Station NEUA was a more recently developed system of the K.U.M. NAMMU-Type instrument, that has a completely different design (https://www.kum-kiel.de/products/nammu.html), with a single flotation, a single pressure tube containing the seismometer, datalogger and batteries. The side-by-side deployment of the different instruments allows a direct comparison and the availability of the oceanographic and meteorological data from the nearby metocean station DARSS-SILL (https://www.io-warnemuende.de/marnet-darss-sill.html) allows a detailed investigations of the instrument-design-related noise sources at OBS stations. Waveform data is available from the GEOFON data centre, under network code 1Q.

1 2