89 documents found in 273ms
# 1
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The Geodetic Observatory Wettzell (Germany) is operated jointly by the Federal Agency for Cartography and Geodesy (BKG) and the Technical University of Munich (TUM) and was established in 1972. Continuous temporal gravity and atmospheric pressure time series from the different SGs is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The Geodetic Observatory Wettzel is located on a mountain ridge of the Bavarian Forest (longitude: 12.88 E, latitude: 49.10 N, height above MSL: 611 m). The crystalline basement of metamorphic rocks (Gneiss) in Wettzell is covered from bottom to top by weathering zones of fractured gneiss, saprolite, periglacial weathering layers and soil, with Cambisols making up the predominant soil type. The climate is temperate with mean annual precipitation of 995 mm and mean annual temperature of 7°C. Land cover in the surroundings of the observatory is dominated by a mosaic of grassland and forest, while grassland, gravel and sealed surfaces of roads and buildings alternateon the grounds of the observatory. Because of the remote, rural location the station is characterized by low environmental noise. Since 1989, an almost uninterrupted time series of gravity and barometric pressure variations was acquired with different SGs. In 1993, a series of repeated measurements with different absolute gravimeters (AG) was started. There are two gravity laboratories at station Wettzell: L1 and L2. L1 was built in 1988. It is an isolated solid building with 2 concrete pillars in separate rooms for SG and AG observations. Now each room is thermally stabilized by air-conditioning system. The new laboratory L2 is a well isolated solid building constructed in 2009. It provides 2 concrete pillars in separate rooms for SG observations and 4 concrete pillars for AG observations and comparisons in a third room. All rooms are thermally stabilized by air-conditioning systems. From November 1999 to October 2010 the dual sphere SG CD029 was operated in L1 and since June 2010 the dual sphere SG030 (after upgrade) is recording in L2. Since March 2011 the dual sphere SG029 (after upgrade) is recording data in L1 again. These data are available at the IGETS database. Earlier, TT60 (1989/09-1995/06) and SG103 (1996/04-1997/07) were installed at L1. Due to the excellent stability of the station and the facilities to inter-compare different AGs, the Geodetic Observatory Wettzell was developed as a regional comparison site which serves as a reference for the national German gravity reference system. At the area of the station, an extensive meteorological (precipitation, air temperature, humidity, wind speed and net radiation) and hydrological (ground water, soil moisture, including a weighing lysimeter) monitoring system is installed and operated in close cooperation with GFZ Potsdam. In addition, data from the superconducting gravimeter iGrav006 operated by GFZ Potsdam from March 2015 until March 2017 are available (Güntner et al., 2017: http://doi.org/10.5880/igets.we.gfz.l1.001).
# 2
Wziontek, Hartmut • Wolf, Peter • Häfner, Michael • Hase, Hayo • Nowak, Ilona • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. In April 2015 the Transportable Integrated Geodetic Observatory (TIGO) was moved from Concepción/Chile to La Plata/Argentina (longitude: 58.14 W, latitude: 34.87 S, height above MSL: 25 m) and is jointly operated by the Federal Agency for Cartography and Geodesy (BKG) and the Argentinian National Scientific and Technical Research Council (CONICET) as Argentinian-German Geodetic Observatory (AGGO). The superconducting gravimeter SG038 was transported 3100 km overland by truck with the sphere floating. AGGO is located near the Rio de la Plata, formed by the confluence of the Paraná and Uruguay rivers and is one of the world’s largest estuaries. Since December 2015, an almost uninterrupted time series of gravity and barometric pressure variations is acquired with SG038. The gravity laboratory is a solid building and equipped with four stable pillars of concrete in one room, founded 5 meters deep. One pillar is used for the SG while the others are available for absolute gravimeters. The site will thus serve as a reference station and comparison site for absolute gravimeters. The site is thermally stabilized by air-conditioning systems. To assess the gravity effects caused by local water storage variations in the groundwater and vadose zone, a hydrological monitoring network was set up in close cooperation with GFZ Potsdam near to the gravimeter building, consisting of a weather station (precipitation, air temperature, air humidity, wind speed, wind direction, solar radiation, net radiation), soil moisture sensors, vertical soil moisture profiles to record water storage changes close to the gravimeter and two groundwater observation wells.
# 3
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The gravimetric station Medicina/Italy operated by the Federal Agency for Cartography and Geodesy (BKG), Germany, and the Department of Physics and Astronomy (DIFA) at the University of Bologna, Italy, was established in 1996. Continuous temporal gravity and atmospheric pressure time series from the SG is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The gravimetric station is located at the premises of the Medicina Radio Observatory (Northern Cross) of Istituto Nazionale di Astrofisica (INAF), 30 km south-east from Bologna in the southeastern Po Plain. The plain runs parallel to the Pede–Apenninic border and represents a sediment-filled foredeep, where a huge sedimentary deposition (more than 5000 m of thickness) occurred during the Plio-Pleistocene. The uppermost stratigraphic sequences in the Plain are made of alternating sands, silts and clays variably interbedded and normally consolidated. Since 1996, an almost uninterrupted time series of gravity and barometric pressure variations are acquired with SG C-023. In the same year a series of repeated absolute gravity measurements with different AGs started. Although the gravity building is not well thermally isolated, the air-conditioning system compensates main temperature variations, keeping the room temperature stable within a range of 5 K. The hut facilitates three pillars of concrete in one room, one used for the SG and two for absolute gravimeters. All pillars show a slight seasonal tilting due to soil consolidation. This effect is mostly compensated by tilt compensation system of the SG. Since June 1995 and November 2004, data from two ground water wells, one in a distance of 500 m, the other nearby, are recorded, supporting the monitoring of local water storage changes.
# 4
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The gravimetric reference station Bad Homburg (Germany) is operated by the Federal Agency for Cartography and Geodesy (BKG) and was established in 1979. Continuous temporal gravity and atmospheric pressure time series from the different SGs is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The district town Bad Homburg is situated about 25 km north-east of Frankfurt/Main (longitude: 8.61 E, latitude: 50.23 N, height above MSL: 188 m) on the southern slope of the Taunus mountains. The gravity station is located inside a cellar of the Landgraves' Castle and is characterized by low environmental noise. Inside the vault a separated housing with insulated walls enables controlled environment. All rooms are thermally stabilized by an air-conditioning system. The station provides 5 separate piers of concrete (2 for SG, 3 for AG) which are grounded on bedrock (approx. 1.8 m deep, on greenschist) and are decoupled from the wooden floor. Since 1981, an almost uninterrupted time series of gravity and barometric pressure variations was acquired with different SGs. In 1993, a series of repeated measurements with different absolute gravimeters (AG) was started. From December 1999 to April 2007 the dual sphere SG CD030 was operated and since February 2007 OSG044 is recording. These data are available at the IGETS database. The first SG installed at the station was TT40 (1981/04-1989/06, later at Richmond/Florida, USA) and TT60 (1985/06-1988/11, later at Wettzell/Germany). Several shorter test registrations were performed with SG103 (1998/12-1999/04), as well as SG030 (2008/02-2010/06) and SG029 (2011/03-2012/04) after upgrades. In November 2003 and May 2004 two ground water wells within a distance of 200 m were constructed to support the monitoring of local water storage changes. Due to the excellent stability of the station and the ability of facilities to inter-compare absolute and superconducting gravimeters, the station Bad Homburg was developed as a reference site for the national German gravity reference system. In Addition, data from the superconducting gravimeter iGrav006 operated by GFZ Potsdam from March 2015 until March 2017 are available (Güntner et al., 2017, http://doi.org/10.5880/igets.we.gfz.l1.001).
# 5
Geiger, Tobias • Frieler, Katja • Bresch, David N.
Abstract: Tropical cyclones (TCs) pose a major risk to societies worldwide. While data on observed cyclones tracks (location of the center) and wind speeds is publicly available these data sets do not contain information about the spatial extent of the storm and people or assets exposed. Here, we apply a simplified wind field model to estimate the areas exposed to wind speeds above 34, 64, and 96 knots. Based on available spatially-explicit data on population densities and Gross Domestic Product (GDP) we estimate 1) the number of people and 2) the sum of assets exposed to wind speeds above these thresholds accounting for temporal changes in historical distribution of population and assets (TCE-hist) and assuming fixed 2015 patterns (TCE-2015). The associated country-event level exposure data (TCE-DAT) covers the period 1950 to 2015. It is considered key information to 1) assess the contribution of climatological versus socioeconomic drivers of changes in exposure to tropical cyclones, 2) estimate changes in vulnerability from the difference in exposure and reported damages and calibrate associated damage functions, and 3) build improved exposure-based predictors to estimate higher-level societal impacts such as long-term effects on GDP, employment, or migration. We validate the adequateness of our methodology by comparing our exposure estimate to estimated exposure obtained from reported wind fields available since 1988 for the United States. We expect that the free availability of the underlying model and TCE-DAT will make research on tropical cyclone risks more accessible to non-experts and stakeholders. Files included in the data set: (1) TCE-DAT_historic-exposure_1950-2015.csv: Exposed population and assets by event and country using historical socio-economic exposure estimates.(2) TCE-DAT_2015-exposure_1950-2015.csv: Exposed population and assets by event and country using fixed socio-economic exposure at 2015 values.(3) Data-description_TCE-DAT_2017.005.pdf: full description of the data set including information on data sources and the description of variables/ data columns
# 6
Guo, X. • Zhao, Q. • Ditmar, P. • Liu, J.
Abstract: The WHU_RL01 GRACE monthly gravity field solutions are produced with the classical dynamic approach at the GNSS Research Center of Wuhan University. Three sets of monthly solutions complete to d/o 60, 90 and 120 are produced without any regularization for the time period from 2002-04 to 2016-07. K-Band range rates with a sampling of 5 seconds and reduced-dynamic orbits with a sampling of 5 minutes are used as observations. To account for the colored noise in the K-Band range-rate measurements, the frequency-dependent data weighting scheme proposed by Ditmar et al. (2007) is adopted. Additionally, a unified weight for the reduced-dynamic orbits is applied based on its a priori precision of 2 cm for each component. The strategy adopted for producing the WHU_RL01 GRACE monthly gravity field models is summarized in Table 1 (please find it in the attached explanatory file). It should be noted that relatively short arcs (6 hours per arc) are used to reduce the resonance effects caused by inaccuracies in initial state vectors and background force models (Colombo, 1984). The reduced-dynamic orbits are also used as observations in our data processing. Although a reduced-dynamic orbit contain certain a priori gravity field information, the resulting bias in the gravity field solutions have been proved to be limited when inverted together with the K-band measurements (Chen et al., 2014; Liu et al., 2010).
# 7
Niemeijer, Andre
Abstract: The Alpine Fault, New Zealand, is a major plate-bounding fault that accommodates 65–75% of the total relative motion between the Australian and Pacific plates. Here we present data on the hydrothermal frictional properties of Alpine Fault rocks that surround the principal slip zones (PSZ) of the Alpine Fault and those comprising the PSZ itself. The samples were retrieved from relatively shallow depths during phase 1 of the Deep Fault Drilling Project (DFDP-1) at Gaunt Creek. Simulated fault gouges were sheared at temperatures of 25, 150, 300, 450, and 600°C in order to determine the friction coefficient as well as the velocity dependence of friction. Friction remains more or less constant with changes in temperature, but a transition from velocity-strengthening behavior to velocity-weakening behavior occurs at a temperature of T = 150°C. The transition depends on the absolute value of sliding velocity as well as temperature, with the velocity-weakening region restricted to higher velocity for higher temperatures.Friction was substantially lower for low-velocity shearing (V<0.3 μm/s) at 600°C, but no transition to normal stress independence was observed. In the framework of rate-and-state friction, earthquake nucleation is most likely at an intermediate temperature of T = 300°C. The velocity-strengthening nature of the Alpine Fault rocks at higher temperatures may pose a barrier for rupture propagation to deeper levels, limiting the possible depth extent of large earthquakes. Our results highlight the importance of strain rate in controlling frictional behavior under conditions spanning the classical brittle-plastic transition for quartzofeldspathic compositions. The data is provided in a .zip folder with 33 subfolders for 33 samples. Detailed information about the files in these subdfolders as well as sensors used, conversions and data specifications is given in the explanatory file Niemeijer-2017-DFDP-explanation-of-folder-structure-and-file-list.pdf.
# 8
Kennett, Douglas J. • Breitenbach, Sebastian F. M. • Aquino, Valorie V. • Lechleitner, Franziska • Ridley, Harriet E. • (et. al.)
Abstract: The proxy record is derived from stalagmite YOK-I from the Yok Balum Cave, Belize. Stalagmite YOK-I was collected in June 2006, ca. 160 m from the western cave entrance. Carbonate was actively precipitating on the tip of this 606.9-mm-long stalagmite when it was collected. The stable isotope climate record covers only the upper 415 mm, while the lower stalagmite section is less suitable for stable isotope studies and was not included in this investigation. Over 4,200 δ18O and δ13C measurements were performed on the upper 415 mm of YOK-I and dated between 40 BC and 2006 AD. The samples were continuously milled at 0.1 mm increments and, depending on growth rate changes in YOK-I, the temporal resolution of the isotopic data fluctuates from 0.01 and 3.68 yrs/0.1 mm, with an average resolution of 0.49 yrs/0.1 mm. Earlier versions of the dataset have been published at the NOAA palaeoclimate data server using a slightly different chronology (Kennett et al., Science 2012, DOI:10.1126/science.1226299). In the study of Ridley et al. (Nat Geo 2015, DOI:10.1038/ngeo2353), we have tuned the chronology of YOK-I with the more precise one of the stalagmite YOK-G. These new data is provided as version 2 in the files YOK-I_d18O_v2.csv (for δ18O) and YOK-I_d13C_v2.csv (for δ13C), consisting of 4047 isotope measurements. Kernel filtering was applied to resample the time series to equidistant annual resolution (Smirnov et al, Sci Rep XXX, DOI: XXX), covering the time span from 15 BC to 2005 AD, resulting in 2021 data values. These filtered versions of the data are provided as files YOK-I_d18O_kernelfiltered.csv and YOK-I_d13C_kernelfiltered.csv. In all files, the first column consists of the age (in yr AD) and the second column (separated from the first column by a semicolon) is the corresponding isotope value (in permil VPDB). The data is presented as four .csv files in a .zip folder.
# 9
Johanna Dreier
Abstract: The Epigravettian site of Blazi cave represents so far the only undisturbed and securly dated Epigravettian site in Albania. The new data fill a research gap for the time of the Late Upper Palaeolithic in the Eastern Adriatic. During the GAP (German-Albanian Palaeolithic research project) campaign in 2015, a large sample of stone artefacts and animal bones was excavated. Their spatial distribution and good preservation indicate an in situ position of the archaeological layer. The tool spectrum contains a high ratio of backed bladelets and microgravette points, typical components of an Epigravettian assemblage. The faunal remains, mainly ibex, exhibit numerous cut and percussion marks, characterising Blazi cave as a specialised ibex hunting site.
# 10
Christian Willmes
Abstract: To provide paleoenvironmental data for a GIS and geostatistic based Species Distribution Modelling (SDM) application, this comprehensive GIS data set was created. The data set consists of DEM based topography, and of paleoclimate layers, that were used as environmental predictor variables for SDM application.
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