Description: R/V Meteor cruise M162 was conducted as a systematic continuation of ongoing work dedicated to understand if and howfluid flow through crust and sedimentscontinues along transform-type plate boundaries and fracture zones away from mid-ocean ridges and continental margins. Central target was the Gloria Fault in the central Northeast Atlantic. Previous findings along the eastern continuation of the Gloria Fault revealed fault-controlled fluid advection and mud volcanism along strike-slip faults in the Horseshoe Abyssal Plain and the Gulf of Cadiz, where fluid geochemistry revealed the admixture of fluids from deeply buried oceanic crust and oldest sediments on top of it. TheGloria Fault itselfis an old, reactivated, and seismically active oceanic fracture zone. During M162 a systematic survey along the main trace of the Gloria Fault between the Azores Plateau and the Madeira-Tore Rise was carried out, including sub-bottom profiler surveys, heat flow transects, gravity corer sampling, as well as video-guided CTD and multicorer deployments. In accordance to recently recorded seismic activity along the fault, there isevidence for tectonic motion both in sub-bottom profiler records and sediment cores. Heat flow measurements revealed values significantly elevated above the background in many places, predominantly along the main fault trace and other active faults.Ina number of placesfluid geochemistry revealed enhanced diagenetic processes in the sediments, implying the potential relation to upward-directed fluid flow. In summary, cruise M162revealed the first complementary data set on heat flow and fluid geochemistry along an oceanic fault zone, which will further our understanding on themes like the alteration of oceanic lithosphere and crust-ocean element exchange.

Description: This study reports on recent developments of the Indonesia Tsunami Early Warning System (InaTEWS), specifically the tsunami modeling components used in the system. It is a dual system: firstly, InaTEWS operates a high-resolution scenario database pre-computed with the finite element model TsunAWI; running in parallel, the system also contains a supra real-time modeling component based on the GPU-parallelized linear long-wave model easyWave, capable of dealing with events outside the database coverage. The evolution of the tsunami scenario database over time is covered in the first sections also touching on the involved capacity building efforts. Starting with a coverage of just the Sunda Arc region, the database now includes scenarios for 15 fault zones. The study is augmented by an investigation of warning products used for early warning; the estimated wave height (EWH) and the estimated time of arrival (ETA). These parameters are determined by easyWave and TsunAWI with model specific approaches. Since the numerical setup of the two models is very different, the extent of variations in warning products is investigated for a number of scenarios, where both pure database scenarios and applications to real events are considered. Finally, the performance of the system in past tsunami events is reviewed to point out major system updates.

Description: Understanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. Atmospheric emissions and concentrations of CH4 continue to increase, making CH4 the second most important human-influenced greenhouse gas in terms of climate forcing, after carbon dioxide (CO2). The relative importance of CH4 compared to CO2 depends on its shorter atmospheric lifetime, stronger warming potential, and variations in atmospheric growth rate over the past decade, the causes of which are still debated. Two major challenges in reducing uncertainties in the atmospheric growth rate arise from the variety of geographically overlapping CH4 sources and from the destruction of CH4 by short-lived hydroxyl radicals (OH). To address these challenges, we have established a consortium of multidisciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate new research aimed at improving and regularly updating the global methane budget. Following Saunois et al. (2016), we present here the second version of the living review paper dedicated to the decadal methane budget, integrating results of top-down studies (atmospheric observations within an atmospheric inverse-modelling framework) and bottomup estimates (including process-based models for estimating land surface emissions and atmospheric chemistry, inventories of anthropogenic emissions, and data-driven extrapolations). For the 2008–2017 decade, global methane emissions are estimated by atmospheric inversions (a top-down approach) to be 576 TgCH4 yr􀀀1 (range 550–594, corresponding to the minimum and maximum estimates of the model ensemble). Of this total, 359 TgCH4 yr􀀀1 or 60% is attributed to anthropogenic sources, that is emissions caused by direct human activity (i.e. anthropogenic emissions; range 336–376 TgCH4 yr􀀀1 or 50 %–65 %). The mean annual total emission for the new decade (2008–2017) is 29 TgCH4 yr􀀀1 larger than our estimate for the previous decade (2000–2009), and 24 TgCH4 yr􀀀1 larger than the one reported in the previous budget for 2003–2012 (Saunois et al., 2016). Since 2012, global CH4 emissions have been tracking the warmest scenarios assessed by the Intergovernmental Panel on Climate Change. Bottom-up methods suggest almost 30% larger global emissions (737 TgCH4 yr􀀀1, range 594–881) than top-down inversion methods. Indeed, bottom-up estimates for natural sources such as natural wetlands, other inland water systems, and geological sources are higher than top-down estimates. The atmospheric constraints on the top-down budget suggest that at least some of these bottom-up emissions are overestimated. The latitudinal distribution of atmospheric observation-based emissions indicates a predominance of tropical emissions ( 65% of the global budget, 〈30 N) compared to mid-latitudes ( 30 %, 30–60 N) and high northern latitudes ( 4 %, 60–90 N). The most important source of uncertainty in the methane budget is attributable to natural emissions, especially those from wetlands and other inland waters. Some of our global source estimates are smaller than those in previously published budgets (Saunois et al., 2016; Kirschke et al., 2013). In particular wetland emissions are about 35 TgCH4 yr􀀀1 lower due to improved partition wetlands and other inland waters. Emissions from geological sources and wild animals are also found to be smaller by 7 TgCH4 yr􀀀1 by 8 TgCH4 yr􀀀1, respectively. However, the overall discrepancy between bottom-up and top-down estimates has been reduced by only 5% compared to Saunois et al. (2016), due to a higher estimate of emissions from inland waters, highlighting the need for more detailed research on emissions factors. Priorities for improving the methane budget include (i) a global, high-resolution map of water-saturated soils and inundated areas emitting methane based on a robust classification of different types of emitting habitats; (ii) further development of process-based models for inland-water emissions; (iii) intensification of methane observations at local scales (e.g., FLUXNET-CH4 measurements) and urban-scale monitoring to constrain bottom-up land surface models, and at regional scales (surface networks and satellites) to constrain atmospheric inversions; (iv) improvements of transport models and the representation of photochemical sinks in top-down inversions; and (v) development of a 3D variational inversion system using isotopic and/or co-emitted species such as ethane to improve source partitioning.

Description: Published

Description: 1561–1623

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: We report primary production and respiration of Posidonia oceanica meadows determined with the non-invasive aquatic eddy covariance technique. Oxygen fluxes were measured in late spring at an open-water meadow (300 m from shore), at a nearshore meadow (60 m from shore), and at an adjacent sand bed. Despite the oligotrophic environment, the meadows were highly productive and highly autotrophic. Net ecosystem production (54 to 119 mmol m-2 d-1) was about one-half of gross primary production. In adjacent sands, net primary production was a tenth- to a twentieth smaller (4.6 mmol m-2 d-1). Thus, P. oceanica meadows are an oasis of productivity in unproductive surroundings. During the night, dissolved oxygen was depleted in the open-water meadow. This caused a hysteresis where oxygen production in the late afternoon was greater than in the morning at the same irradiance. Therefore, for accurate measurements of diel primary production and respiration in this system, oxygen must be measured within the canopy. Generally, these measurements demonstrate that P. oceanica meadows fix substantially more carbon than they respire. This supports the high rate of organic carbon accumulation and export for which the ecosystem is known.

Description: The presented thesis successfully provided the missing knowledge about the tox-in profiles of every received sample strain by using the selected reaction monitor-ing method in an UHPLC-MS/MS instrument. Out of the 69 strains from eleven Amphidinium species, a total of 32 strains from six different species produced at least one amphidinol. During the quantification of the identified amphidinols the amount of toxin contained in a single cell, called cell quote, was calculated, which was crucial since Amphidinium species not only show hemolytic, cytotoxic and ichthyotoxic activities (Mooney et al., 2010), but were reported to create harmful algal blooms that can have devastating impacts on public health, fisheries re-sources, and coastal commodities (Díaz et al., 2019). A linkage between the calcu-lated cell quote in the amphidinols and the toxicity effects could be investigated in future bioassays. The stated hypothesis concerning the possibility to discover previously unknown amphidinol variations in the introduction of this work proved to be correct. The analysis of the complete sample set undertaken by the neutral loss and full scan methods resulted in 79 masses possibly containing amphidinol variations, that subsequently were examined about similarities to known amphidinols by using an enhanced product ion scan (EPI). Out of the 79 recorded EPI scans, eleven sub-stances were identified as possible new amphidinol variations based on their fragmentation spectrum. Finally, fragmentation pattern proposals were stated for every of the eleven unknown substances. Future works should implement the discovered amphidinol variations into the existing SRM method, and additionally quantify the discovered variations about their toxin profile and cell quote since the proposed fragmentation patterns were the last step completed in this thesis. Otherwise, the procedure for the discovery of new amphidinol variations proved to work well and can therefore be applied to new sample strains in upcoming projects.

Description: International Ocean Discovery Program (IODP) Expedition 382 in the Scotia Sea’s Iceberg Alley recovered among the most continuous and highest resolution stratigraphic records in the Southern Ocean near Antarctica spanning the last 3.3 Myr. Sites drilled in Dove Basin (U1536/U1537) have well‐resolved magnetostratigraphy and a strong imprint of orbital forcing in their lithostratigraphy. All magnetic reversals of the last 3.3 Myr are identified, providing a robust age model independent of orbital tuning. During the Pleistocene, alternation of terrigenous versus diatomaceous facies shows power in the eccentricity and obliquity frequencies comparable to the amplitude modulation of benthic δ18O records. This suggests that variations in Dove Basin lithostratigraphy during the Pleistocene reflect a similar history as globally integrated ice volume at these frequencies. However, power in the precession frequencies over the entire ∼3.3 Myr record does not match the amplitude modulation of benthic δ18O records, suggesting Dove Basin contains a unique record at these frequencies. Comparing the position of magnetic reversals relative to local facies changes in Dove Basin and the same magnetic reversals relative to benthic δ18O at North Atlantic IODP Site U1308, we demonstrate Dove Basin facies change at different times than benthic δ18O during intervals between ∼3 and 1 Ma. These differences are consistent with precession phase shifts and suggest climate signals with a Southern Hemisphere summer insolation phase were recorded around Antarctica. If Dove Basin lithology reflects local Antarctic ice volume changes, these signals could represent ice sheet precession‐paced variations not captured in benthic δ18O during the 41‐kyr world.

Description: The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.

Description: Scotia Sea and the Drake Passage is key towards understanding the development of modern oceanic circulation patterns and their implications for ice sheet growth and decay. The sedimentary record of the southern Scotia Sea basins documents the regional tectonic, oceanographic and climatic evolution since the Eocene. However, a lack of accurate age estimations has prevented the calibration of the reconstructed history. The upper sedimentary record of the Scotia Sea was scientifically drilled for the first time in 2019 during International Ocean Discovery Program (IODP) Expedition 382, recovering sediments down to ∼643 and 676 m below sea floor in the Dove and Pirie basins respectively. Here, we report newly acquired high resolution physical properties data and the first accurate age constraints for the seismic sequences of the upper sedimentary record of the Scotia Sea to the late Miocene. The drilled record contains four basin-wide reflectors – Reflector-c, -b, -a and -a' previously estimated to be ∼12.6 Ma, ∼6.4 Ma, ∼3.8 Ma and ∼2.6 Ma, respectively. By extrapolating our new Scotia Sea age model to previous morpho-structural and seismic-stratigraphic analyses of the wider region we found, however, that the four discontinuities drilled are much younger than previously thought. Reflector-c actually formed before 8.4 Ma, Reflector-b at ∼4.5/3.7 Ma, Reflector-a at ∼1.7 Ma, and Reflector-a' at ∼0.4 Ma. Our updated age model of these discontinuities has major implications for their correlation with regional tectonic, oceanographic and cryospheric events. According to our results, the outflow of Antarctic Bottom Water to northern latitudes controlled the Antarctic Circumpolar Current flow from late Miocene. Subsequent variability of the Antarctic ice sheets has influenced the oceanic circulation pattern linked to major global climatic changes during early Pliocene, Mid-Pleistocene and the Marine Isotope Stage 11.

Description: International Ocean Discovery Program Expedition 382, Ice-berg Alley and Subantarctic Ice and Ocean Dynamics, investigatedthe long-term climate history of Antarctica, seeking to understandhow polar ice sheets responded to changes in insolation and atmo-spheric CO2 in the past and how ice sheet evolution influencedglobal sea level and vice versa. Five sites (U1534–U1538) weredrilled east of the Drake Passage: two sites at 53.2°S at the northernedge of the Scotia Sea and three sites at 57.4°–59.4°S in the southernScotia Sea. We recovered continuously deposited late Neogene sed-iments to reconstruct the past history and variability in AntarcticIce Sheet (AIS) mass loss and associated changes in oceanic and at-mospheric circulation.The sites from the southern Scotia Sea (Sites U1536–U1538)will be used to study the Neogene flux of icebergs through “IcebergAlley,” the main pathway along which icebergs calved from the mar-gin of the AIS travel as they move equatorward into the warmer wa-ters of the Antarctic Circumpolar Current (ACC). In particular,sediments from this area will allow us to assess the magnitude oficeberg flux during key times of AIS evolution, including the follow-ing: •The middle Miocene glacial intensification of the East Antarctic Ice Sheet, •The mid-Pliocene warm period, •The late Pliocene glacial expansion of the West Antarctic Ice Sheet, •The mid-Pleistocene transition (MPT), and •The “warm interglacials” and glacial terminations of the last 800 ky. We will use the geochemical provenance of iceberg-rafted detri-tus and other glacially eroded material to determine regionalsources of AIS mass loss. We will also address interhemisphericphasing of ice sheet growth and decay, study the distribution andhistory of land-based versus marine-based ice sheets around thecontinent over time, and explore the links between AIS variabilityand global sea level.By comparing north–south variations across the Scotia Sea be-tween the Pirie Basin (Site U1538) and the Dove Basin (Sites U1536and U1537), Expedition 382 will also deliver critical information onhow climate changes in the Southern Ocean affect ocean circulationthrough the Drake Passage, meridional overturning in the region,water mass production, ocean–atmosphere CO2 transfer by wind-induced upwelling, sea ice variability, bottom water outflow fromthe Weddell Sea, Antarctic weathering inputs, and changes in oce-anic and atmospheric fronts in the vicinity of the ACC.Comparing changes in dust proxy records between the ScotiaSea and Antarctic ice cores will also provide a detailed reconstruc-tion of changes in the Southern Hemisphere westerlies on millen-nial and orbital timescales for the last 800 ky. Extending the oceandust record beyond the last 800 ky will help to evaluate dust-climatecouplings since the Pliocene, the potential role of dust in iron fertil-ization and atmospheric CO2 drawdown during glacials, andwhether dust input to Antarctica played a role in the MPT. The principal scientific objective of Subantarctic Front SitesU1534 and U1535 at the northern limit of the Scotia Sea is to recon-struct and understand how intermediate water formation in thesouthwest Atlantic responds to changes in connectivity between theAtlantic and Pacific basins, the “cold water route.” The SubantarcticFront contourite drift, deposited between 400 and 2000 m waterdepth on the northern flank of an east–west trending trough off theChilean continental shelf, is ideally situated to monitor millennial-to orbital-scale variability in the export of Antarctic IntermediateWater beneath the Subantarctic Front. During Expedition 382, werecovered continuously deposited sediments from this drift span-ning the late Pleistocene (from ~0.78 Ma to recent) and from thelate Pliocene (~3.1–2.6 Ma). These sites are expected to yield a widearray of paleoceanographic records that can be used to interpretpast changes in the density structure of the Atlantic sector of theSouthern Ocean, track migrations of the Subantarctic Front, andgive insights into the role and evolution of the cold water route oversignificant climate episodes, including the following: •The most recent warm interglacials of the late Pleistocene and •The intensification of Northern Hemisphere glaciation.