ALBERT

Description: Abstract Permian carbonate reservoir rocks (Stassfurt-Carbonate) of the CO2-province (Lower Saxony Basin, NW Germany) are locally characterised by high amounts of CO2 leading to serious problems on exploration. In order to receive information on the major CO2 sources and CO2 migration and accumulation processes mineralogical, geochemical and stable isotope analyses (13C, 18O) were carried out on authigenic precipitations within the Stassfurt carbonate rocks (Ca2). These rocks contain early diagenetic (e.g., formed in soft sediment) carbonate minerals (calcite, dolomite) and anhydrite in concretions and small cracks. In addition, large (up to 2 cm wide) carbonate-cemented fractures formed in solid Ca2 rocks. Semi-quantitative estimates of the diagenetic mineral content showed variations between the investigated rock cores. Nine out of 12 Ca2 rock cores are derived from wells situated in the area of modern CH4-rich reservoirs and have distinct fracture systems developed. In contrast, the other three rock cores are from wells characterised by CO2-rich reservoirs and lack fractures of similar thickness. The assumed relationship between tectonically induced fractures and the gas content of the Ca2 reservoir rocks implies CO2 degassing of the Ca2 rocks at approximately 102 °C to 150 °C (assumed δ18Opore water variation from 0‰ to + 4‰ SMOW). REE distribution indicates at least three types of fracture- and crack-filling carbonates. Two carbonate generations formed from evolving diagenetic pore waters whereas one type reflects carbonate formation under hydrothermal influence. The ages of these cementations derived from Rb/Sr and U/Pb isotope analyses indicate their formation during late stage of/or after the inversion of the Lower Saxony Basin in Late Cretaceous times. The stable carbon isotope composition of the authigenic carbonate minerals reflects at least two carbon source endmembers available during diagenesis. Whereas many early-formed carbonates are related to the Permian 13C-rich carbon source, those carbonates which precipitated or recrystallised during early to late stage diagenesis and/or were induced by local tectonic events incorporated 12C-enriched CO2 from organic degradation processes. The stable oxygen isotope values of authigenic carbonates probably still reflect low temperatures of mineral formation from Permian sea water (as it is assumed for “non” recrystallised carbonates) or late-stage high-temperature (up to 150 °C) precipitation from sea water-derived pore waters which may have been locally influenced by 18O-enriched fluids. However, most of the carbonate samples investigated are recrystallised (crystal enlargement of concretionary and fracture carbonate is observed) and hence, these carbonates are at least partly re-equilibrated (original 18O-content reduced) with surrounding pore waters at elevated temperature. Similar to the authigenic carbonate at least two sources may explain the concentration/carbon isotope relationship of modern CO2 present in the Ca2 reservoir rocks. An organic-derived CO2 endmember source (δ13C near − 20‰) is present in relatively low concentrations whereas large CO2 concentrations derived from an endmember source with an isotope value near 0‰. Although the latter source is unknown such “heavy” CO2 sources are most likely attributed to carbonate decomposition processes.

Description: Over the last 20 years, a large number of instruments have provided plasma density measurements in Earth's topside ionosphere. In order to utilize all of the collected observations for empirical modeling, it is necessary to ensure that they do not exhibit systematic differences and are adjusted to the same reference frame. In this study, we compare satellite plasma density observations from Gravity Recovery and Climate Experiment (GRACE), Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC), CHAllenging Minisatellite payload (CHAMP), Swarm, and Communications/Navigation Outage Forecasting System (C/NOFS) missions. Electron densities retrieved from GRACE K-Band Ranging (KBR) system, previously shown to be in excellent agreement with incoherent scatter radar (ISR) measurements, are used as a reference. We find that COSMIC radio occultation (RO) densities are highly consistent with GRACE-KBR observations showing a mean relative difference of urn:x-wiley:21699380:media:jgra56751:jgra56751-math-0001, and therefore no calibration factors between them are necessary. We utilize the outstanding three-dimensional coverage of the topside ionosphere by the COSMIC mission to perform conjunction analysis with in situ density observations from CHAMP, C/NOFS and Swarm missions. CHAMP measurements are lower than COSMIC by urn:x-wiley:21699380:media:jgra56751:jgra56751-math-0002. Swarm densities are generally lower at daytime and higher at nighttime compared to COSMIC. C/NOFS ion densities agree well with COSMIC, with a relative bias of urn:x-wiley:21699380:media:jgra56751:jgra56751-math-0003. The resulting cross-calibration factors, derived from the probability distribution functions, help to eliminate the systematic leveling differences between the data sets, and allow using these data jointly in a large number of ionospheric applications.

Description: This work presents a new extension to B-Splines that enables them to model functions on directed tree graphs such as non-braided river networks. The main challenge of the application of B-splines to graphs is their definition in the neighbourhood of nodes with more than two incident edges. Achieving that the B-splines are continuous at these points is non-trivial. For both, simplification reasons and in view of our application, we limit the graphs to directed tree graphs. To fulfil the requirement of continuity, the knots defining the B-Splines need to be located symmetrically along the edges with the same direction. With such defined B-Splines, we approximate the topography of the Mekong River system from scattered height data along the river. To this end, we first test and validate successfully the method with synthetic water level data, with and without added annual signal. The quality of the resulting heights is assessed besides others by means of root mean square errors (RMSE) and mean absolute differences (MAD). The RMSE values are 0.26 m and 1.05 m without and with added annual variation respectively and the MAD values are even lower with 0.11 m and 0.60 m. For the second test, we use real water level observations measured by satellite altimetry. Again, we successfully estimate the river topography, but also discuss the short comings and problems with unevenly distributed data. The unevenly distributed data leads to some very large outliers close to the upstream ends of the rivers tributaries and in regions with rapidly changing topography such as the Mekong Falls. Without the outlier removal the standard deviation of the resulting heights can be as large as 50 m with a mean value of 15.73 m. After the outlier removal the mean standard deviation drops to 8.34 m.

Description: The following authors were omitted from the original version of this Data Descriptor: Markus Reichstein and Nicolas Vuichard. Both contributed to the code development and N. Vuichard contributed to the processing of the ERA-Interim data downscaling. Furthermore, the contribution of the co-author Frank Tiedemann was re-evaluated relative to the colleague Corinna Rebmann, both working at the same sites, and based on this re-evaluation a substitution in the co-author list is implemented (with Rebmann replacing Tiedemann). Finally, two affiliations were listed incorrectly and are corrected here (entries 190 and 193). The author list and affiliations have been amended to address these omissions in both the HTML and PDF versions. © 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.

Description: Brachiopods present a key fossil group for Phanerozoic palaeo-environmental and palaeo-oceanographical reconstructions, owing to their good preservation and abundance in the geological record. Yet to date, hardly any geochemical proxies have been calibrated in cultured brachiopods and only little is known on the mechanisms that control the incorporation of various key elements into brachiopod calcite. To evaluate the feasibility and robustness of multiple Element/Ca ratios as proxies in brachiopods, specifically Li/Ca, B/Ca, Na/Ca, Mg/Ca, Sr/Ca, Ba/Ca, as well as Li/Mg, we cultured Magellania venosa, Terebratella dorsata and Pajaudina atlantica under controlled experimental settings over a period of more than two years with closely monitored ambient conditions, carbonate system parameters and elemental composition of the culture medium. The experimental setup comprised of two control aquariums (pH0 = 8.0 and 8.15, T = 10 °C) and treatments where pCO2 − pH (pH1 = 7.6 and pH2 = 7.35), temperature (T = 16 °C) and chemical composition of the culture medium were manipulated. Our results indicate that the incorporation of Li and Mg is strongly influenced by temperature, growth effects as well as carbonate chemistry, complicating the use of Li/Ca, Mg/Ca and Li/Mg ratios as straightforward reliable proxies. Boron partitioning varied greatly between the treatments, however without a clear link to carbonate system parameters or other environmental factors. The partitioning of both Ba and Na varied between individuals, but was not systematically affected by changes in the ambient conditions. We highlight Sr as a potential proxy for DIC, based on a positive trend between Sr partitioning and carbonate chemistry in the culture medium. To explain the observed dependency and provide a quantitative framework for exploring elemental variations, we devise the first biomineralisation model for brachiopods, which results in a close agreement between modelled and measured Sr distribution coefficients. We propose that in order to sustain shell growth under increased DIC, a decreased influx of Ca2+ to the calcifying fluid is necessary, driving the preferential substitution of Sr2+ for Ca2+ in the crystal lattice. Finally, we conducted micro-computed tomography analyses of the shells grown in the different experimental treatments. We present pore space – punctae – content quantification that indicates that shells built under increased environmental stress, and in particular elevated temperature, contain relatively more pore space than calcite, suggesting this parameter as a potential novel proxy for physiological stress and even environmental conditions.

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.