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  • 1
    Publication Date: 2024-06-18
    Description: Abstract
    Description: The dataset contains the seismic weight drop data acquired in Private Reserve Santa Gracia, Chile. The data acquisition was conducted as a part of the EarthShape project in the subproject of Geophysical Imaging of the Deep EarthShape (GIDES). The seismic line was setup to cut across an existing borehole location with core and geophysical logging data available (Krone et al., 2021; Weckmann et al., 2020). The data was acquired to image the deep weathering zone identified by the borehole data across the seismic profile. Included in the datasets are the raw data of the CUBE data logger, SEG-Y data of the recorded shots, and the shot and receiver geometry data. A vital aspect of comprehending the interplay between geological and biological processes lies in the imaging of the critical zone, located deep beneath the surface, where the transition from unaltered bedrock to fragmented regolith occurs. It had been hypothesized that the depth of such weathering zone is dependent on the climate condition of the area. A more humid climate with higher precipitation will result in a deeper weathering front. As a part of the EarthShape project (SPP-1803 ‘EarthShape: Earth Surface Shaping by Biota’), specifically the Geophysical Imaging of the Deep EarthShape (GIDES - Grant No. KR 2073/5-1), we aim to image the weathering zone using the geophysical approach. Using the seismic method, we can differentiate different weathered layers based on the seismic velocity while also providing a 2D subsurface image of the critical zone. We conducted a seismic weight drop experiment in the Private Reserve Santa Gracia, Chile, to observe the depth of the weathering zone in a semi-arid climate and compare the resulting model with existing borehole data (Krone et al., 2021; Weckmann et al., 2020). The acquired data can then be used for multiple seismic imaging techniques, including body wave tomography and multichannel analysis of surface waves.
    Description: Other
    Description: The DFG Priority Program 1803 "EarthShape - Earth Surface Shaping by Biota" (2016-2022; https://www.earthshape.net/) explored between scientific disciplines and includes geoscientists and biologists to study from different viewpoints the complex question how microorganisms, animals, and plants influence the shape and development of the Earth’s surface over time scales from the present-day to the young geologic past. All study sites are located in the north-to-south trending Coastal Cordillera mountains of Chile, South America. These sites span from the Atacama Desert in the north to the Araucaria forests approximately 1300 km to the south. The site selection contains a large ecological and climate gradient ranging from very dry to humid climate conditions.
    Keywords: Geophysics ; seismic ; weight drop ; weathering zone ; critical zone ; bedrock ; granite ; passive seismic ; 3C sensor ; EarthShape ; Chile ; Coastal Cordillera ; Private Reserve Santa Gracia ; CONTROLLED_SOURCE_SEISMOLOGY 〉 REFRACTION ; CONTROLLED_SOURCE_SEISMOLOGY 〉 WEIGHT-DROP_SOURCE ; CONTROLLED_SOURCE_SEISMOLOGY 〉 NEAR_SURFACE ; PASSIVE_SEISMIC 〉 STATIONS ; SENSOR 〉 GEOPHONE ; SENSOR 〉 3-C ; LAND ; SEG-Y_DATA_FORMAT ; MINISEED_DATA_FORMAT ; CONTROLLED_SOURCE_SEISMOLOGY 〉 RAW_DATA ; CONTROLLED_SOURCE_SEISMOLOGY 〉 VERTICALLY_STACKED_DATA ; EARTH SCIENCE 〉 SOLID EARTH ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 EARTHQUAKES 〉 SEISMIC PROFILE
    Type: Dataset , Dataset
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  • 2
    Publication Date: 2024-04-26
    Description: Abstract
    Description: A network of 210 continuously running, digital seismic stations equipped with short-period sensors (200 stations) and broadband sensors (10 stations) was deployed in an area of ~8 x ~6 km in the Irish Midlands (north of Collinstown) for a time period of ~6 weeks. The network was part of the EU project VECTOR (https://vectorproject.eu) aiming to investigate – among others – possible solutions for least invasive forms of exploration for mineral resources. In this context the collected data was mainly used to derive a 3D model of the subsurface (seismic shear wave velocity) using ambient noise tomography (down to ~1.5km depth). We thank all field crews for their excellent work rendered to the project. Waveform data is available from the GEOFON data centre, under network code 7W, and is embargoed until Feb 2025.
    Keywords: EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 EARTHQUAKES ; In Situ/Laboratory Instruments 〉 Magnetic/Motion Sensors 〉 Seismometers ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS 〉 SEISMOLOGICAL STATIONS ; Seismometers ; Geophone[g] ; Velocity ; MiniSEED ; Passive seismic ; GIPP ; MESI ; Raw[g] ; Local network ; Vertical component[g] ; Three-component[g] ; Land[g] ; Geophysics ; Natural
    Type: Dataset , Seismic Network
    Format: ~300G
    Format: .mseed
    Format: XML
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  • 3
    Publication Date: 2019-08-17
    Description: The formation mechanism of terrestrial planetary is still poorly understood, and has been the subject of numerous experimental studies. Several mechanisms have been proposed by which metal-mainly iron with some nickel-could have been extracted from a silicate mantle to form the core. Most recent models involve gravitational sinking of molten metal or metal sulphide through a partially or fully molten mantle that is often referred to as a'magma ocean. Alternative models invoke percolation of molten metal along an interconnected network (that is, porous flow) through a solid silicate matrix. But experimental studies performed at high pressures have shown that, under hydrostatic conditions, these melts do not form an interconnected network, leading to the widespread assumption that formation of metallic cores requires a magma ocean. In contrast, here we present experiments which demonstrate that shear deformation to large strains can interconnect a significant fraction of initially isolated pockets of metal and metal sulphide melts in a solid matrix of polycrystalline olivine. Therefore, in a dynamic (nonhydrostatic) environment, percolation remains a viable mechanism for the segregation and migration of core-forming melts in a solid silicate mantle.
    Keywords: Geophysics
    Type: Nature; 403; 883-886
    Format: text
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  • 4
    Publication Date: 2019-08-17
    Description: We use the first simultaneous in situ measurements of ClONO2, ClO, and HCl acquired using the NASA ER-2 aircraft during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission to test whether these three compounds quantitatively account for total inorganic chlorine (Cly) in the lower stratosphere in 1997. We find (ClO + ClONO2 + HCl)/Cly = 0.92 +/- 0.10, where Cly is inferred from in situ measurements of organic chlorine source gases. These observations are consistent with our current understanding of the budget and partitioning of Cly in the lower stratosphere. We find no evidence in support of missing inorganic chlorine species that compose a significant fraction of Cly. We apply the analysis to earlier ER-2 observations dating from 1991 to investigate possible causes of previously observed discrepancies in the inorganic chlorine budget. Using space shuttle, satellite, balloon, and aircraft measurements in combination with ER-2 data, we find that the discrepancy is unlikely to have been caused by missing chlorine species or an error in the photolysis rate of chlorine nitrate. We also find that HCl/Cly is not significantly controlled by aerosol surface area density in the lower stratosphere.
    Keywords: Geophysics
    Type: Paper-1999JD900996 , Journal of Geophysical Research (ISSN 0148-0227); 105; D2; 1957-1971
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  • 5
    Publication Date: 2019-08-16
    Description: In the fall of 1997, during an Intensive Observation Period (IOP), the Atmospheric Radiation Measurement (ARM) program conducted a study of water vapor abundance measurement at its Southern Great Plains (SGP) site. Among a large number of instruments, four sun-tracking radiometers were present to measure the columnar water vapor (CWV). All four solar radiometers retrieve CWV by measuring total solar transmittance in the 0.94-gm water vapor absorption band and subtracting contributions due to Rayleigh, ozone and aerosol transmittances. The aerosol optical depth comparisons among the same four radiometers has been presented elsewhere (Geophys. Res. Lett., 26, 17, 2725-2728, 1999). We have used three different methods to retrieve CWV. In a first round of comparison no attempt was made to standardize on the same radiative transfer model and its underlying water vapor spectroscopy. In the second round of comparison we used the same line-by-line code (which includes recently corrected H2O spectroscopy) to retrieve CAN from all four suntracking radiometers. This decreased the mean CWV by 8% or 13%. The spread of 8% in the solar radiometer results found when using the same model is an indication of the other-than-model uncertainties involved in determining CWV from solar transmittance measurements with current instrumentation.
    Keywords: Geophysics
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  • 6
    Publication Date: 2019-08-16
    Description: Trajectory hunting (i.e., a technique to find air parcels sampled at least twice over the course of a few days) is applied to analyze Upper Atmosphere Research Satellite (UARS) measurements in conjunction with the Atmospheric and Environmental Research, Inc. (AER) photochemical box model. As a case study, we investigate rapid chlorine activation in the Arctic lower stratosphere on December 29, 1992 associated with a polar stratospheric cloud (PSC) event. Eleven air parcels that have been sampled several times along five-day trajectories at the 465 K (approx. 46 hPa), 520 K (approx. 31 hPa), and 585 K (approx. 22 hPa) levels were investigated. For the first time, the latest versions of the Cryogenic Limb Array Etalon Spectrometer (CLAES, version 9) and Microwave Limb Sounder (MLS, version 5) data sets are analyzed, and their consistency is assessed. A detailed sensitivity study with the AER photochemical box model along these trajectories leads to the conclusion that for the December 24-29, 1992 episode: (1) the individual CLAES ClONO2 and MLS ClO measurements are self-consistent within their uncertainties; and (2) most of the time, UARS measurements of ClO, ClONO2, HNO3, and aerosol extinction at 780 cm(exp -1) agree within the range of their uncertainties with the model calculations. It appears that the HNO3 and aerosol extinction measurements for four parcels at 520 K look more supportive for the nitric acid trihydrate (NAT) scheme, However, the uncertainties in the individual UARS measurements and UK Meteorological Office temperature do not allow a definite discrimination between the NAT and supercooled ternary solution (STS) PSC schemes for this chlorine activation episode in December 1992.
    Keywords: Geophysics
    Type: Paper-1999JD901054 , Journal of Geophysical Research (ISSN 0148-0227); 105; D3; 4003-4018
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  • 7
    Publication Date: 2019-08-16
    Description: The overall objective of this grant was to: 1) Quantify thermospheric neutral wind behavior in the ionosphere. This was to be achieved by developing an improved empirical wind model. 2) Validating the procedure for obtaining winds from the height of the peak density. 3) Improving the model capabilities and making updated versions of the model available to other scientists. The approach is to use neutral winds derived from ionosonde measurements of the height of the peak electron density (h(sub m)F(sub 2)). One of the proposed first year tasks was to perform some validation studies on the method. Substantial progress has been made with regard to both the empirical model and the validation study. Funding from this grant has also enabled a number of fruitful collaborations with other researchers; one of the stated aims in the proposal. Graduate student Mayra Martinez has developed the mathematical formulation for the empirical wind model as part of her dissertation. As proposed, authors continued validation studies of the technique for determining winds from h(sub m)F(sub 2). They are submitted a paper to the Journal of Geophysical Research in December 1996 entitled "Therinospheric neutral winds at southern mid-latitudes: comparison of optical and ionosonde h(sub m)F(sub 2) methods. A second paper entitled "Ionospheric behavior at a southern mid-latitude in March 1995" has come out of the March 1995 data set and was published in The Journal of Geophysical Research. A new algorithm was developed. The ionosphere also have been modeled.
    Keywords: Geophysics
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  • 8
    Publication Date: 2019-08-15
    Description: This research program investigated changes of dynamical and chemical structure of the lower stratosphere and how they are related to elements of the tropospheric general circulation. These considerations were explored in total ozone data from TOMS on board the Nimbus-7 satellite. It was shown that most of the daily variance of total ozone was accounted for by quasi-horizontal transport of ozone along isentropic surfaces in the lower stratosphere. Air descending along theta surfaces experiences compression that increases the local ozone number density and column abundance. Just the reverse is experienced by air ascending along isentropics surfaces. Together, these mechanisms provide an explanation for ozone "mini-hole" phenomenon, which punctuates the circulation of the Southern Hemisphere.
    Keywords: Geophysics
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  • 9
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    In:  CASI
    Publication Date: 2019-08-15
    Description: THz spectroscopy of the atmosphere has been driven by the need to make remote sensing measurements of OH. While the THz region can be used for sensitive detection on many atmospheric molecules, the THz region is the best region for measuring the diurnal behavior of stratospheric OH by remote sensing. The infrared region near 3 microns suffers from chemiluminescence and from spectral contamination due to water. The ultraviolet region near 300 nm requires solar illumination. The three techniques for OH emission measurements in the THz region include Fourier Transform interferometry, Fabry-Perot interferometry, and heterodyne radiometry. The first two use cryogenic direct detectors while the last technique uses a local oscillator and a mixer to down convert the THz signal to GHz frequencies. All techniques have been used to measure stratospheric OH from balloon platforms. OH results from the Fabry-Perot based FILOS instrument will be given. Heterodyne measurement of OH at 2.5 THz has been selected to be a component of the Microwave Limb Sounder on the Earth Observing System CHEM-1 polar satellite. The design of this instrument will be described. A balloon-based prototype heterodyne 2.5 THz radiometer had its first flight on, 24 May 1998. Results form this flight will be presented.
    Keywords: Geophysics
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  • 10
    Publication Date: 2019-08-15
    Description: This report provides a broad outline of the total body of research conducted during the past three years. We report on detailed model studies of the precise way in which infrared limb scanning satellites explicitly detect gravity waves, and use these insights to resolve earlier discrepant zonal mean estimates of gravity wave variances from satellite limb scanners. Detailed analysis of CRISTA temperature fluctuations are outlined, which provide new global information on long-wavelength stratospheric gravity waves generated by mountains, tropical convection and the mid-latitude jet stream-vortex system, as well as interactions higher in the mesosphere with the diurnal tide. The detailed insights gained from analyzing CRISTA data are applied to provide a multiyear analysis of stratospheric mountain waves over the Andes evident in MLS limb-track data. We also demonstrate for the first time that stratospheric temperature data from the CLAES instrument on UARS resolved gravity waves, and we highlight mountain wave information in a subset of these data. Final conclusions and recommendations are set forth, and the present findings are directly related to the original goals of the research contract. A full list of publications that resulted from this research is provided.
    Keywords: Geophysics
    Type: Rept-5090-12
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