ALBERT

Description: The global character of the millennial-scale climate variability associated with the Dansgaard–Oeschger (DO) events in Greenland has been well-established for the last glacial cycle. Mainly due to the sparsity of reliable data, however, the spatial coherence of corresponding variability during the penultimate cycle is less clear. New investigations of European loess records from Marine Isotope Stage (MIS) 6 reveal the occurrence of alternating loess intervals and paleosols (incipient soil horizons), similar to those from the last climatic cycle. These paleosols are correlated, based on their stratigraphical position and numbers as well as available optically stimulated luminescence (OSL) dates, with interstadials described in various Northern Hemisphere records and in GLt_syn, the synthetic 800 kyr record of Greenland ice core δ18O. Therefore, referring to the interstadials described in the record of the last climate cycle in European loess sequences, the four MIS 6 interstadials can confidently be interpreted as DO-like events of the penultimate climate cycle. Six more interstadials are identified from proxy measurements performed on the same interval, leading to a total of 10 interstadials with a DO-like event status. The statistical similarity between the millennial-scale loess–paleosol oscillations during the last and penultimate climate cycle provides direct empirical evidence that the cycles of the penultimate cycle are indeed of the same nature as the DO cycles originally discovered for the last glacial cycle. Our results thus imply that their underlying cause and global imprint were characteristic of at least the last two climate cycles.

Description: Twitter is an established social media platform valued by scholars as an open way to disseminate scientific information and to publicly discuss research results. Scientific discussions on Twitter are viewed by the media, who can then pass on information to the wider public. Social media is used widely by geoscientists, but there is little documentation currently available regarding the benefits or limitations of this for the scientist or the public. Here, we use the example of two 2018 earthquake-related events that were widely commented on by geoscientists on Twitter: the Palu Mw 7.5 earthquake and related tsunami in Indonesia and the long-duration Mayotte island seismovolcanic crisis in the Indian Ocean. We built our study on a content and contextual analysis of selected Twitter threads about the geophysical characteristics of these events. From the analysis of these two examples, we show that Twitter promotes a very rapid building of knowledge in the minutes to hours and days following an event via an efficient exchange of information and active discussion between the scientists themselves and the public. We discuss the advantages and potential pitfalls of this relatively novel way of making scientific information accessible to scholarly peers and lay people. We argue that scientific discussion on Twitter breaks down the traditional “ivory tower” of academia, contributes to the growing trend towards open science, and may help people to understand how science is developed and, in turn, to better understand the risks related to natural/environmental hazards.

Description: Wetland vegetation provide strong controls on greenhouse gas fluxes but impacts of elevated atmospheric carbon dioxide (CO2) levels on greenhouse gas emissions from wetlands are poorly understood. This study aims to investigate if elevated atmospheric CO2 enhance methane (CH4) emissions from subarctic wetlands and to determine if responses are comparable or species specific within the Cyperaceae, an important group of artic wetland plants. To achieve this we carried out a combined field and laboratory investigation to measure of CO2 and CH4 fluxes. The wetland was a CH4 source with comparable fluxes from areas with and without vegetation and across the different sedge communities. In contrast, the net ecosystem exchange of CO2 differed with sedge species. Within the laboratory experiment plants grown at double ambient (800 ppm) CO2, total biomass of Eriophorum vaginatum and Carex brunnescens increased, whereas the total biomass of E. angustifolium and C. acuta decreased, compared to the control (400 ppm CO2). These changes in biomass were associated with corresponding changes in CH4 flux. E. vaginatum and C. brunnescens mesocosms produced more CH4 when grown in 800 ppm atmospheric CO2 when compared to 400 ppm CO2 with E. angustifolium and C. acuta producing less. Additionally, redox potential and carbon substrate availability in the pore water differed among the plant treatments and in response to the elevated CO2 treatment. Together, this suggests species specific controls of CH4 emissions in response to elevated CO2, which facilitate differential plant growth responses and modification of the rhizosphere environments. Our study highlights species composition as an important control of greenhouse gas feedbacks in a CO2 rich future, which need to be considered in models aiming to predict how ecosystems respond to climate change.

Description: In this paper we present and discuss the performance of the procedure for earthquake location and characterization implemented in the Italian Candidate Tsunami Service Provider at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome. Following the ICG/NEAMTWS guidelines, the first tsunami warning messages are based only on seismic information, i.e., epicenter location, hypocenter depth, and magnitude, which are automatically computed by the software Early-est. Early-est is a package for rapid location and seismic/tsunamigenic characterization of earthquakes. The Early-est software package operates using offline-event or continuous-real-time seismic waveform data to perform trace processing and picking, and, at a regular report interval, phase association, event detection, hypocenter location, and event characterization. Early-est also provides mb, Mwp, and Mwpd magnitude estimations. mb magnitudes are preferred for events with Mwp ≲ 5.8, while Mwpd estimations are valid for events with Mwp ≳ 7.2. In this paper we present the earthquake parameters computed by Early-est between the beginning of March 2012 and the end of December 2014 on a global scale for events with magnitude M ≥ 5.5, and we also present the detection timeline. We compare the earthquake parameters automatically computed by Early-est with the same parameters listed in reference catalogs. Such reference catalogs are manually revised/verified by scientists. The goal of this work is to test the accuracy and reliability of the fully automatic locations provided by Early-est. In our analysis, the epicenter location, hypocenter depth and magnitude parameters do not differ significantly from the values in the reference catalogs. Both mb and Mwp magnitudes show differences to the reference catalogs. We thus derived correction functions in order to minimize the differences and correct biases between our values and the ones from the reference catalogs. Correction of the Mwp distance dependency is particularly relevant, since this magnitude refers to the larger and probably tsunamigenic earthquakes. Mwp values at stations with epicentral distance Δ ≲ 30° are significantly overestimated with respect to the CMT-global solutions, whereas Mwp values at stations with epicentral distance Δ ≳ 90° are slightly underestimated. After applying such distance correction the Mwp provided by Early-est differs from CMT-global catalog values of about δ Mwp ≈ 0.0 ∓ 0.2. Early-est continuously acquires time-series data and updates the earthquake source parameters. Our analysis shows that the epicenter coordinates and the magnitude values converge within less than 10 min (5 min in the Mediterranean region) toward the stable values. Our analysis shows that we can compute Mwp magnitudes that do not display short epicentral distance dependency overestimation, and we can provide robust and reliable earthquake source parameters to compile tsunami warning messages within less than 15 min after the event origin time.

Description: A goal of geophysical inversion is to identify all models which give an acceptable misfit between predicted and observed data. However, because of the complexity of Earth structure, the non-linearity of physical processes in the Earth, and the insufficiency of geophysical data, many geophysical inverse problems may have a large number of distinct, acceptable solutions. These problems may be characterized by a complicated surface for the misfit function in the solution parameter space. For exploring such a surface, direct inversion and simple random search methods are often inadequate. However, directed search methods such as the genetic algorithm can be configured to balance convergent and random processes to find large sets of solutions that span the acceptable regions of complicated misfit surfaces.

Description: In this paper we present the procedure for earthquake location and characterization implemented in the Italian candidate Tsunami Service Provider at INGV in Roma. Following the ICG/NEAMTWS guidelines, the first tsunami warning messages are based only on seismic information, i.e. epicenter location, hypocenter depth and magnitude, which are automatically computed by the software Early-est. Early-est is a package for rapid location and seismic/tsunamigenic characterization of earthquakes. The Early-est software package operates on offline-event or continuous-realtime seismic waveform data to perform trace processing and picking, and, at a regular report interval, phase association, event detection, hypocenter location, and event characterization. In this paper we present the earthquake parameters computed by Early-est from the beginning of 2012 till the end of December 2014 at global scale for events with magnitude M ≥ 5.5, and the detection timeline. The earthquake parameters computed automatically by Early-est are compared with reference manually revised/verified catalogs. From our analysis the epicenter location and hypocenter depth parameters do not differ significantly from the values in the reference catalogs. The epicenter coordinates generally differ less than 20 ∓ 20 km from the reference epicenter coordinates; focal depths are less well constrained and differ generally less than 0 ∓ 30 km. Early-est also provides mb, Mwp and Mwpd magnitude estimations. mb magnitudes are preferred for events with Mwp ≲ 5.8, while Mwpd are valid for events with Mwp ≳ 7.2. The magnitude mb show wide differences with respect to the reference catalogs, we thus apply a linear correction mbcorr = mb · 0.52 + 2.46, such correction results into δmb ≈ 0.0 ∓ 0.2 uncertainty with respect the reference catalogs. As expected the Mwp show distance dependency. Mwp values at stations with epicentral distance Δ ≲ 30° are significantly overestimated with respect the CMT-global solutions, whereas Mwp values at stations with epicentral distance Δ ≳ 90° are slightly underestimated. We thus apply a 3rd degree polynomial distance correction. After applying the distance correction, the Mwp provided by Early-est differs from CMT-global catalog values of about δ Mwp ≈ 0.0 ∓ 0.2. Early-est continuously acquires time series data and updates the earthquake source parameters. Our analysis shows that the epicenter coordinates and the magnitude values converge rather quickly toward the final values. Generally we can provide robust and reliable earthquake source parameters to compile tsunami warning message within less than about 15 min after event origin time.

Description: The grass family (Poaceae) is one of the most economically important plant groups in the world today. In particular many major food crops, including rice, wheat, maize, rye, barley, oats and millet, are grasses that were domesticated from wild progenitors during the Holocene. Archaeological evidence has provided key information on domestication pathways of different grass lineages through time and space. However, the most abundant empirical archive of floral change – the pollen record – has been underused for reconstructing grass domestication patterns because of the challenges of classifying grass pollen grains based on their morphology alone. Here, we test the potential of a novel approach for pollen classification based on the chemical signature of the pollen grains measured using Fourier transform infrared (FTIR) microspectroscopy. We use a dataset of eight domesticated and wild grass species, classified using k-nearest neighbour classification coupled with leave-one-out cross validation. We demonstrate a 95 % classification success rate on training data and an 82 % classification success rate on validation data. This result shows that FTIR spectroscopy can provide enhanced taxonomic resolution enabling species level assignment from pollen. This will enable the full testing of the timing and drivers of domestication and agriculture through the Holocene.

Description: Gegenstand dieser Studie ist die würm-spätglaziale und holozäne Talentwicklung am Zusammenfluss von Lech und Donau im Nördlichen Alpenvorland. Die morphologischen Formen im Untersuchungsgebiet wurden mit Hilfe von Geländekartierungen und digitalen Geländemodellen aufgenommen. Die Ablagerungen beider Flüsse wurden in zahlreichen Aufschlüssen untersucht und deren Alter mit Radiokarbon- sowie Lumineszenzdatierungen bestimmt. Daneben wurden auch archäologische Daten und historische Karten genutzt, um die Altersstellung der einzelnen Terrassen einzugrenzen. Im Untersuchungsgebiet bildet eine spätglaziale Niederterrasse die älteste Flussterrasse innerhalb des Talbodens, die allerdings nur im Donautal unterhalb der Lechmündung erhalten ist. In beiden Tälern sind präboreale bis boreale Terrassenflächen nur kleinräumig verbreitet, während ein Sockelschotter gleichen Alters weiträumig unter jüngeren Ablagerungen anzutreffen ist. Atlantische Flussbettablagerungen sind im Untersuchungsgebiet nicht zu finden. Dagegen dominieren subboreale und subatlantische Terrassen das Lechmündungsgebiet. Die heutigen Flussläufe von Lech und Donau werden von bis zu sechs subatlantischen Terrassen begleitet. Deren Verbreitung und morphologisches Erscheinungsbild verweist im Donautal oberhalb der Lechmündung auf einen mäandrierenden Flusslauf, die der jüngsten Lechterrasse auf ein verzweigtes Gerinnebettmuster. Unterhalb der Lechmündung treten dagegen Übergangsformen beider Flussgrundrisstypen auf.