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  • 2020-2023  (41)
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  • 1
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    Performance of a Rotational Sensor to Decipher Volcano Seismic Signals on Etna, Italy (2022)
    Eibl, Eva P. S. ; Rosskopf, Martina ; Sciotto, Mariangela ; [et al.]
    Details
    Publication Date: 2022-10-04
    Description: Volcano‐seismic signals such as long‐period events and tremor are important indicators for volcanic activity and unrest. However, their wavefield is complex and characterization and location using traditional seismological instrumentation is often difficult. In 2019 we recorded the full seismic wavefield using a newly developed 3C rotational sensor co‐located with a 3C traditional seismometer on Etna, Italy. We compare the performance of the rotational sensor, the seismometer and the Istituto Nazionale di Geofisica e Vulcanologia‐Osservatorio Etneo (INGV‐OE) seismic network with respect to the analysis of complex volcano‐seismic signals. We create event catalogs for volcano‐tectonic (VT) and long‐period (LP) events combining a STA/LTA algorithm and cross‐correlations. The event detection based on the rotational sensor is as reliable as the seismometer‐based detection. The LP events are dominated by SH‐type waves. Derived SH phase velocities range from 500 to 1,000 m/s for LP events and 300–400 m/s for volcanic tremor. SH‐waves compose the tremor during weak volcanic activity and SH‐ and SV‐waves during sustained strombolian activity. We derive back azimuths using (a) horizontal rotational components and (b) vertical rotation rate and transverse acceleration. The estimated back azimuths are consistent with the INGV‐OE event location for (a) VT events with an epicentral distance larger than 3 km and some closer events, (b) LP events and tremor in the main crater area. Measuring the full wavefield we can reliably analyze the back azimuths, phase velocities and wavefield composition for VT, LP events and tremor in regions that are difficult to access such as volcanoes.
    Description: Plain Language Summary: Traditional seismographs usually include mass and spring systems which measure vibrations constrained to up‐down, north‐south and east‐west directions. We compare the traditional seismometer to a rotational sensor which measures ground rotation around the same three directions. We installed a rotational sensor on Etna volcano in 2019 to test these new sensors in a volcanic environment. We compare the performance of the rotational sensor, a traditional seismometer and the Istituto Nazionale di Geofisica e Vulcanologia‐Osservatorio Etneo (INGV‐OE) seismometer network. We detect two types of a few second long earthquakes and find that the rotational sensor performs as good as the seismometer. We use the rotational sensor to calculate directions of the earthquake locations and find that most directions agree with the INGV‐OE network location and the area of the active craters. We find that for some earthquakes the ground only moved horizontally while for others it also moved up and down. Using a rotational sensor on a volcano we can easily and reliably estimate the ground motion, the speed of the earthquake waves in the ground and understand better how these earthquakes are generated.
    Description: Key Points: We tested the performance of a rotational sensor compared to a seismometer and a seismic network using long‐period (LP), volcano‐tectonic (VT) events and tremor on Etna. LP and VT events are dominated by SH‐ and SV‐waves, respectively. Tremor changed from SH‐ to a mixed wavefield during strombolian eruptions. LP event and tremor back azimuths point to the main craters consistent with the Istituto Nazionale di Geofisica e Vulcanologia location; VT event back azimuths are at times consistent.
    Description: Eurovolc
    Description: Daimler Benz Foundation
    Description: https://doi.org/10.14470/ME7564062119
    Keywords: ddc:551.2
    Language: English
    Type: doc-type:article
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  • 2
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    Environmental Regulation of the Nitrogen Supply, Mean Trophic Position, and Trophic Enrichment of Mesozooplankton in the Mekong River Plume and Southern South China Sea (2021)
    Details
    Publication Date: 2022-04-01
    Description: The mean trophic position (TP) of mesozooplankton largely determines how much mass and energy is available for higher trophic levels like fish. Unfortunately, the ratio of herbivores to carnivores in mesozooplankton is difficult to identify in field samples. Here, we investigated changes in the mean TP of mesozooplankton in a highly dynamic environment encompassing four distinct habitats in the southern South China Sea: the Mekong River plume, coastal upwelling region, shelf waters, and offshore oceanic waters. We used a set of variables derived from bulk and amino acid nitrogen stable isotopes from particulate organic matter and four mesozooplankton size fractions to identify changes in the nitrogen source and TP of mesozooplankton across these habitats. We found clear indications of a shift in N sources for biological production from nitrate in near‐coastal waters with shallow mixed layer depths toward an increase in diazotroph‐N inputs in oceanic waters with deep mixed layer depths where diazotrophs shaped the phytoplankton community. The N source shift was accompanied by a lengthening of the food chain (increase in the TP). This may provide further support for the connection between diazotrophy and the indirect routing of N through the marine food web. Our combined bulk and amino acid δ15N approach also allowed us to estimate the trophic enrichment (TE) of mesozooplankton across the entire regional ecosystem. When put in the context of literature values, a high TE of 5.1‰ suggested a link between ecosystem heterogeneity and the less efficient transfer of mass and energy across trophic levels.
    Description: Plain Language Summary: Zooplankton are one of the central pillars of the marine food web and form an important link between the production of organic matter by phytoplankton and biomass at higher trophic levels (e.g., fish). Of particular interest are mesozooplankton (0.2–20 mm in size), which encompass a diverse assemblage of animals utilizing a range of feeding strategies, including herbivory, omnivory, and carnivory. Since mass and energy are lost with each trophic step, their prevailing feeding strategy determines the availability of mass and energy to the upper food web. The exact relationship between carnivores and herbivores in mesozooplankton has so far only been studied with complex experiments or in homogenous environments. We have now resolved zooplankton feeding relationships in a highly dynamic marine environment. Specifically, we used stable nitrogen isotopes in amino acids and bulk organic matter in combination with a habitat‐delineating method for phytoplankton to directly determine the ratio of carnivores to herbivores in zooplankton from dynamic habitats in the South China Sea. The mass and energy transfer across trophic levels is less efficient in such variable marine environments compared to stable open ocean systems. These findings represent a big step toward understanding the dynamics of planktonic food webs in general.
    Description: Key Points: Trophic structure of mesozooplankton is regulated by similar environmental factors such as phytoplankton assemblages. Diazotrophy and nutrient availability correlated with enhanced mesozooplankton carnivory in a complex tropical marine ecosystem. Mass and energy transfer across trophic levels of planktonic food webs are less efficient in spatially and temporally variable ecosystems.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: National Foundation for Science and Technology Development (NAFOSTED) http://dx.doi.org/10.13039/100007224
    Description: National Aeronautics and Space Administration (NASA) http://dx.doi.org/10.13039/100000104
    Description: Schmidt Ocean Institute
    Description: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Description: https://doi.org/10.5061/dryad.bk3j9kdbv
    Keywords: ddc:577.7
    Language: English
    Type: doc-type:article
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  • 3
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    Uncertainty in Aerosol Optical Depth From Modern Aerosol‐Climate Models, Reanalyses, and Satellite Products (2022)
    Details
    Publication Date: 2022-04-01
    Description: Despite the implication of aerosols for the radiation budget, there are persistent differences in data for the aerosol optical depth (τ) for 1998–2019. This study presents a comprehensive evaluation of the large‐scale spatio‐temporal patterns of mid‐visible τ from modern data sets. In total, we assessed 94 different global data sets from eight satellite retrievals, four aerosol‐climate model ensembles, one operational ensemble product, two reanalyses, one climatology and one merged satellite product. We include the new satellite data SLSTR and aerosol‐climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and the Aerosol Comparisons between Observations and Models Phase 3 (AeroCom‐III). Our intercomparison highlights model differences and observational uncertainty. Spatial mean τ for 60°N – 60°S ranges from 0.124 to 0.164 for individual satellites, with a mean of 0.14. Averaged τ from aerosol‐climate model ensembles fall within this satellite range, but individual models do not. Our assessment suggests no systematic improvement compared to CMIP5 and AeroCom‐I. Although some regional biases have been reduced, τ from both CMIP6 and AeroCom‐III are for instance substantially larger along extra‐tropical storm tracks compared to the satellite products. The considerable uncertainty in observed τ implies that a model evaluation based on a single satellite product might draw biased conclusions. This underlines the need for continued efforts to improve both model and satellite estimates of τ, for example, through measurement campaigns in areas of particularly uncertain satellite estimates identified in this study, to facilitate a better understanding of aerosol effects in the Earth system.
    Description: Plain Language Summary: Aerosols are known to affect atmospheric processes. For instance, particles emitted during dust storms, biomass burning and anthropogenic activities affect air quality and influence the climate through effects on solar radiation and clouds. Although many studies address such aerosol effects, there is a persistent difference in current estimates of the amount of aerosols in the atmosphere across observations and complex climate models. This study documents the data differences for aerosol amounts, including new estimates from climate‐model simulations and satellite products. We quantify considerable differences across aerosol amount estimates as well as regional and seasonal variations of extended and new data. Further, this study addresses the question to what extent complex climate models have improved over the past decades in light of observational uncertainty.
    Description: Key Points: Present‐day patterns in aerosol optical depth differ substantially between 94 modern global data sets. The range in spatial means from individual satellites is −11% to +17% of the multi‐satellite mean. Spatial means from climate model intercomparison projects fall within the satellite range but strong regional differences are identified.
    Description: Hans‐Ertel‐Center for Weather Research
    Description: Collaborative Research Centre 1211
    Description: Max‐Planck‐Institute for Meteorology
    Keywords: ddc:551.5
    Language: English
    Type: doc-type:article
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  • 4
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    Shear wave splitting in the Alpine region (2022)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2022-04-21
    Description: To constrain seismic anisotropy under and around the Alps in Europe, we study SKS shear wave splitting from the region densely covered by the AlpArray seismic network. We apply a technique based on measuring the splitting intensity, constraining well both the fast orientation and the splitting delay. Four years of teleseismic earthquake data were processed, from 723 temporary and permanent broad-band stations of the AlpArray deployment including ocean-bottom seismometers, providing a spatial coverage that is unprecedented. The technique is applied automatically (without human intervention), and it thus provides a reproducible image of anisotropic structure in and around the Alpine region. As in earlier studies, we observe a coherent rotation of fast axes in the western part of the Alpine chain, and a region of homogeneous fast orientation in the Central Alps. The spatial variation of splitting delay times is particularly interesting though. On one hand, there is a clear positive correlation with Alpine topography, suggesting that part of the seismic anisotropy (deformation) is caused by the Alpine orogeny. On the other hand, anisotropic strength around the mountain chain shows a distinct contrast between the Western and Eastern Alps. This difference is best explained by the more active mantle flow around the Western Alps. The new observational constraints, especially the splitting delay, provide new information on Alpine geodynamics. © 2021 The Author(s) 2021. Published by Oxford University Press on behalf of The Royal Astronomical Society.
    Description: Published
    Description: 1996–2015
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Design options for the new international market mechanism under article 6.4 of the Paris agreement (2020)
    Dessau-Roßlau : Umweltbundesamt
    Details
    Publication Date: 2022-02-18
    Description: In this project commissioned by the German Environment Agency, important aspects of the mechanism under Article 6.4 of the Paris Agreement were examined in more detail. This mechanism is to succeed the CDM under the Kyoto Protocol from 2021 onwards, but it will contain decisive improvements, especially with regard to a robust accounting of emission reductions and better integration into the national climate policy of the host country. The report is addressed to the international experts, in particular to the delegates to the climate conference and observers, and is therefore written in English. A German summary is included. The following topics are covered: How does the mechanism achieve an overall reduction of global emissions? Are there opportunities to use benchmarks to establish baselines? Can contributions to increasing ambition be made by using Art. 6.4? What contribution can the voluntary market make to increasing ambition in the future? Introduction of incentives for the participation of private companies under Art. 6.4 of the PA. The role of the Art. 6.4 mechanism on the way to a net zero emission world. The project provides a contribution to the general discussion in the EU as well as to the Article 6 - Negotiations under the UNFCCC. It is a contribution that presents backgrounds and interrelationships for individual questions concerning the design of the new market mechanisms under Article 6 and can thus contribute to a more informed decision-making process.Since there are, however, several different ways of designing a mechanism that can avoid double counting and provide incentives for increasing ambition, this project is only one of several current contributions to the international discussion.
    Keywords: ddc:320
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
    Type: report , doc-type:report
    Format: application/pdf
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  • 6
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    Options for fostering a net-zero GHG emission world under the Paris article 6.4 mechanism : discussion paper (2020)
    Berlin : German Emissions Trading Authority (DEHSt)
    Details
    Publication Date: 2022-02-18
    Description: The new mechanism defined under Article 6.4 of the Paris Agreement is supposed to allow for international cooperation with regard to climate change mitigation and thereby enable an increase in overall mitigation. Nevertheless, the design of the mechanism under Article 6.4 should also make sure that it is not be in conflict with the long-term goal of net-zero GHG emissions but even better foster national pathways leading to this objective. Building this into the mechanism requires to shift the focus from short- and mid-term considerations to the long-term perspective in one way or another. This discussion paper explores three different approaches that may help to foster the long-term objective of net-zero GHG emissions in the operationalization of Article 6.4, namely positive and negative lists, additionality with regard to a baseline consistent with both, NDCs and long-term targets, as well as adaptation of existing instruments and criteria from climate finance. The detailed discussion of the ap-proaches shows that the approaches should not be seen as mutually exclusive but rather as comple-mentary to each other. From the analyses, two storylines emerge how to combine aspects of the differ-ent approaches in a reasonable way to foster the long-term objective of net-zero GHG emissions under Article 6.4.
    Keywords: ddc:320
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
    Type: workingpaper , doc-type:workingPaper
    Format: application/pdf
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  • 7
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    Ein Mini-Hochmoor auf dem Campus der SLU in Uppsala (2020)
    In:  DGMT | ZA 34278
    Details
    Publication Date: 2022-03-23
    Description: Im Juni 2020 wurde ein kleines Hochmoor im Wissenspark der SLU in Uppsala angelegt. Ob Moorbeete sich als landschaftsarchitektonisches Element im urbanen, nemoralen Teil Schwedens eignen, wird anhand des Etablierungserfolgs der eingebrachten oligo- bis mesotrophen Torfmoosarten entlang eines Gradienten von Bult zu Schlenke untersucht.
    Description: In June 2020, a small bog was created at the Knowledge Garden of SLU in Uppsala. If moss pits are suitable elements for landscape architecture in the urban, nemoral part of Sweden will be examined through the establishment of the used oligo- to mesotrophic peat mosses on a gradient from hollow to hummock.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: ddc:553.21
    Language: German
    Type: doc-type:article
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  • 8
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    Mid‐Infrared Spectroscopy of Anorthosite Samples From Near Manicouagan Crater, Canada, as Analogue for Remote Sensing of Mercury and Other Terrestrial Solar System Objects (2021)
    Details
    Publication Date: 2022-03-22
    Description: We investigated mid‐infrared reflectance spectra of anorthosite samples from Mt. Briand near the Manicouagan impact structure. Microprobe analyses of the plagioclase minerals reveal that they have a similar chemical composition (labradoritic), which is corroborated by the location of the Christiansen Feature at around 7.96 μm (1256 cm−1). However, their respective spectral shapes differ from each other in the region of the reststrahlen bands. This is linked to the degree of Al,Si order within the plagioclase minerals, which also correlates with the previously assumed distance of the sample site to the impact melt. Powdering and sieving led to remarkable changes in the spectra resulting from different mechanical stability of minerals contained in the sample. Our data show that even very weakly shocked (6–10 GPa, shockstage S2) anorthosites could show spectra of Al,Si disordered plagioclase which we attribute to post shock heating after the impact shock. Consequently, the degree of Al,Si order has to be taken into account in the interpretation of remote sensing data. A comparison of synthetic linear mixture with an average Mercury spectrum reveals the possible presence of more or less anorthositic material with reduced degree of Al,Si order of the plagioclase component on Mercury's surface. The results of our study are helpful for the interpretation of data returned by space missions, especially for MERTIS ‐ an infrared spectrometer on its way to Mercury.
    Description: Plain Language Summary: The studied rocks, which contain predominantly the feldspar mineral plagioclase, are very common in our Solar System, for example, on the Moon and probably also on Mercury. The surface of planets without atmosphere, like Moon and Mercury are constantly the target of asteroid impacts. These impacts cause changes in the constituents of the rocks. The studied samples are from the area near a meteorite crater and show weak effects of the former meteorite impact. The infrared spectra of the samples have different shapes. This shape does not correlate with the chemical composition, but with the distribution of aluminum and silicon ions in the plagioclase components of the investigated samples. This distribution is often underestimated in remote sensing. Our study shows that this distribution of these ions is related to a previously assumed distance of the sample location from the impact. The results are useful for interpreting remote sensing data coming back from space missions. In our case, in particular, from an infrared spectrometer on its way to the planet Mercury called MERTIS. The study also presents a spectrum calculated from various mineral spectra comparable to the samples analyzed. This spectrum shows similarities to an average Mercury surface spectrum and suggests that the feldspars on the Mercury surface have a very disordered ion distribution.
    Description: Key Points: Low impact shock with proposed impact melt influences Al,Si order of plagioclases. Grinding of rocks leads to modal changes of the minerals. Potential plagioclases with reduced degree of Al,Si order on the surface of Mercury.
    Description: Deutsches Zentrum für Luft‐ und Raumfahrt (DLR) http://dx.doi.org/10.13039/501100002946
    Language: English
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  • 9
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    Benefits of simulating precipitation characteristics over Africa with a regionally-coupled atmosphere–ocean model (2022)
    In:  EPIC3Climate Dynamics, ISSN: 0930-7575
    Details
    Publication Date: 2022-07-13
    Description: High-quality climate information at appropriate spatial and temporal resolution is essential to develop and provide tailored climate services for Africa. A common method to produce regional climate change data is to dynamically downscale global climate projections by means of regional climate models (RCMs). Deficiencies in the representation of the sea surface temperatures (SSTs) in earth system models (ESMs) and missing atmosphere–ocean interactions in RCMs contribute to the precipitation bias. This study analyzes the influence of the regional atmosphere–ocean coupling on simulated precipitation and its characteristics over Africa, and identifies those regions providing an added value using the regionally coupled atmosphere–ocean model ROM. For the analysis, the MPI-ESM-LR historical simulation and emission scenario RCP8.5 were dynamically downscaled with ROM at a spatial resolution of 0.22° × 0.22° for the whole African continent, including the tropical Atlantic and the Southwest Indian Ocean. The results show that reduced SST warm biases in both oceans lead to more realistic simulated precipitation over most coastal regions of Sub-Saharan Africa and over southern Africa to varying degrees depending on the season. In particular, the annual precipitation cycles over the coastal regions of the Atlantic Ocean are closer to observations. Moreover, total precipitation and extreme precipitation indices in the coupled historical simulation are significantly lower and more realistic compared to observations over the majority of the analyzed sub-regions. Finally, atmosphere–ocean coupling can amplify or attenuate climate change signals from precipitation indices or even change their sign in a regional climate projection.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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  • 10
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    BEST PRACTICE GUIDELINE Measurement of carbon dioxide, methane and nitrous oxide fluxes between soil-vegetation-systems and the atmosphere using non-steady state chambers (2022)
    Arbeitsgruppe Bodengase, Deutsche Bodenkundliche Gesellschaft | Göttingen
    Details
    Publication Date: 2022-06-23
    Description: This Best Practice Guideline was been initiated by the Working Group Soil Gases (AG Bodengase) of the German Soil Science Society (Deutsche Bodenkundliche Gesellschaft). Our intention was to collect and aggregate the expertise of different working groups in our field. As a compendium, this guideline may help both beginners and experts to meet the practical and theoretical challenges of measuring soil gas fluxes with non-steady state chamber systems.
    Description: German Soil Science Society, Working Group Soil Gases
    Description: manual
    Keywords: ddc:631.4
    Language: English
    Type: doc-type:book
    Format: 70
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