An emerging solution in mine waste remediation is the use of biological processes, such as microbial sulfate reduction (MSR), to immobilize metals, reducing their bioavailability and buffering the pH of acid mine drainage. Apart from laboratory tests and local observations of natural MSR in e.g. single wetlands, little is known about spatio-temporal characteristics of freshwater MSR from multiple locations within entire hydrological catchments. We here applied an isotopic fractionation (δ34S-values in SO42-) and Monte-Carlo based mixing analysis scheme to detect MSR and its variation across two major mining regions (Imetjoki, Sweden and Khibiny, Russia) in the Arctic part of Europe under different seasonal conditions. Results indicate a range of catchment-scale MSR-values in the Arctic of ~ 5-20% where the low end of the range was associated with the non-vegetated, mountainous terrain of the Khibiny catchment, having low levels of dissolved organic carbon (DOC). The high-end of the range was related to vegetated conditions provided by the Imetjoki catchment that also contains wetlands, lakes and local aquifers. These prolong hydrological residence times and support MSR hot-spots reaching values of ~40%. Present results additionally show evidence of MSR-persistence over different seasons, indicating large potential, even under relatively cold conditions, of using MSR as part of nature-based solutions to mitigate adverse impacts of (acid) mine drainage. The results call for more detailed investigations regarding potential field-scale correlations between MSR and individual landscape and hydro-climatic characteristics, which e.g. can be supported by the here utilized isotopic fractionation and mixing scheme.

Crustal velocity variation within impact-related seismic zones is commonly attributed to mechanisms such as pore pressure changes, dense fracture network, and compositional variation. In this study, we combine seismic tomography, rock physics analysis, and potential field modeling to quantitatively investigate the mechanisms that influence crustal velocity variation in the Charlevoix Seismic Zone (CSZ), a meteorite impact-related seismic zone in eastern Canada. Earthquakes in the CSZ align along two broad NE-SW trending clusters related to reactivated paleo-rift faults. Within the impact structure, the earthquakes are diffusely distributed and lower velocity bodies are ubiquitous which can be attributed to crustal damage from tectonic inheritance exacerbated by the meteorite impact. The Bouguer gravity anomaly decreases southeastward across the St. Lawrence River due to density disparity between rocks in the Grenville Province and the Appalachians. We find a higher velocity body northeast of the impact structure that does not exhibit an observable gravity anomaly, which suggests the presence of a rock (e.g. anorthosite) of comparable density but a higher elastic moduli within another rock (e.g. charnockite). Outside the impact structure, compositional variations control velocity changes, whereas inside the impact structure, velocity variations can be explained by porosity enhancement of up to 10% by low (0.1) aspect ratio cracks. Our results suggest that intense fracturing and compositional alteration, rather than pore pressure, control velocity variations, hence earthquake processes in the CSZ.

Estimates of global carbon stocks in coastal wetlands reveal that these are some of the most efficient carbon-sequestering environments in the world, which has prompted a renewed interest in conservation and restoration programs as an opportunity for greenhouse gas abatement. Accumulation of carbon in coastal wetlands is linked to diverse factors such as the type of vegetation, geomorphic setting, and sediment supply. Feedbacks between these factors and the tidal flow conditions drive the dynamics of carbon accumulation rates. Climate change-induced sea-level rise has been shown to increase the vulnerability to submergence of saltmarsh and mangroves in coastal wetlands, even if accommodation and landward colonization are possible. These potential losses of wetland vegetation combined with the reduced productivity of newly colonized areas will directly affect the capacity of the wetlands to sequester carbon from sediments and root growth. Here, we implement an eco-geomorphic model to simulate vegetation dynamics, soil carbon accumulation, and changes in soil carbon stock for a restored mangrove-saltmarsh wetland experiencing accelerated sea-level rise. We evaluate model outcomes for existing conditions and two different management scenarios aimed at mitigating sea-level rise effects and conserve wetland vegetation. Even though some management measures can result in partial conservation of wetland vegetation, they do not necessarily result in the best option for soil carbon capture. Our results suggest that accelerated sea-level can trigger accelerated wetland colonization resulting in wetland areas with limited opportunities for soil carbon capture from sediment and root mineralization, an issue that has not been considered in previous studies.

GOSAT (Greenhouse gases Observing SATellite) observations ameliorate inversion analysis of greenhouse gas emissions. Meso-scale atmospheric transport model (AIST-MM, National Institute of Advanced Industrial Science and Technology-Mesoscale Model) and global-scale transport model (NICAM-TM, Nonhydrostatic ICosahedral Atmospheric Model-Transport Model) have been coupled for GOSAT data assimilation in order to estimate CO2 emission from mega-city Tokyo. However, forests in the north and west of Kanto region, of which Tokyo Metropolis is the center, generate significant biogenic CO2 fluxes and such atmosphere-biosphere gas exchange remains to be properly calculated during the modeling processes. In this study, we use MODIS products to simulate regional GPP (gross primary production), vegetational and soil respirations based on BEAMS (Biosphere model integrating Eco-physiological And Mechanistic approaches using Satellite data) algorithms. By integrating this atmosphere-terrestrial ecosystem carbon balance module to our regional inversion analysis, we aim at more precise estimation of CO2 emission from Tokyo. Reference https://doi.org/10.1175/1520-0450(1995)034<1439:TTILWA>2.0.CO;2 https://doi.org/10.2151/jmsj.79.11 https://doi.org/10.2151/jmsj.2011-306 https://doi.org/10.1029/2005JG000045 https://doi.org/10.1016/j.rse.2011.03.007

The Waves instrument aboard Juno is a sophisticated radio astronomy observatory investigating Jupiter's auroral radio emissions and plasma wave interactions. Waves records electrical field properties using two monopole antennas, which are connected to form a dipole. The receiving properties of the Waves dipole changes quite remarkably over the instruments frequency range from near DC to 40 MHz. In this contribution we outline Waves' electrical sensor properties above the quasi-static frequency range and provide detailed directivity pattern and insertion loss figures of the instrument for science application and data analysis.

Located at the northern tip of the Altiplano, the Abancay Deflection marks abruptly the latitudinal segmentation of the Central Andes spreading over the Altiplano to the south and the Eastern Cordillera northward. The striking contrast in terms of morphology between the low-relief Altiplano and the high-jagged Eastern Cordillera makes this area a privileged place to determine spatio-temporal variations in surface and/or rock uplift and discuss the latest phase of the formation of the Central Andes. Here, we aim to quantify exhumation and uplift patterns in the Abancay Deflection since 40 Ma, and present new apatite (U-Th)/He and fission-track data from five altitudinal profiles and additional individual samples. Age-Elevation relationships and thermal modeling both evidence that the Abancay Deflection experienced a moderate, spatially-uniform and steady exhumation at 0.2±0.1 km/m.y. between 40 Ma and ~5 Ma implying common large-scale exhumation mechanisms. From ~5 Ma, while the northern part of the Eastern Cordillera and the Altiplano registered similar ongoing slow exhumation, the southern part of the Eastern Cordillera experienced one order-of-magnitude of exhumation acceleration (1.2±0.4 km/m.y). This differential exhumation since ~5 Ma implies active tectonics, river capture and incision affecting the southern Eastern Cordillera. 3D thermo-kinematic modeling favors a tectonic decoupling between the Altiplano and the Eastern Cordillera through backthrusting activity of the Apurimac fault. We speculate that the Abancay Deflection, with its “bulls-eye” structure and significant exhumation rate since 5 Ma, may represent an Andean proto-syntaxis, similar to the syntaxes described in the Himalaya or Alaska.

The structurally complex region of Tempe Terra, located in the northeast of the Tharsis Rise on Mars, preserves deformation related to the growth of Tharsis and lies along the trendline formed by the Tharsis Montes volcanoes. We characterise the spatiotemporal tectonic evolution of Tempe Terra based on comprehensive structural mapping. From this mapping, we identified 16 cross-cutting fault sets and placed these in relative time order, based on a hybrid approach using cross-cutting relationships and buffered crater counting. We are thus able to provide a broad framework for understanding the timing of development for the Tharsis Rise and Tharsis Montes axial trend. Our work shows that Tempe Terra has experienced three distinct stages of tectonic activity from the Middle Noachian to the Late Hesperian. Stage 1 involved E--W extension followed by localised NE--SW extension, which produced local zones of N and NW faulting through the centre and west of Tempe Terra in the Noachian. Stage 2 produced intense NE-oriented faulting concentrated along the Tharsis Montes axial trend in the Early Hesperian as a result of a discrete period of NW--SE extension and local volcanism. Stage 3 involved NW--SE extension coinciding with Tharsis volcanic activity, which generated a regional fabric of ENE-trending graben distributed across Tempe Terra from the Early to Late Hesperian. We observe an overall peak in tectonic activity in the Early Hesperian and find that Tharsis-related extensional deformation in the form of NE-oriented radial faulting did not start in Tempe Terra until this time.

Quantitative analysis of crustal thickness evolution across past geological periods poses significant challenges but provides invaluable insights into the planet’s geological history. It may help uncover new areas with potential critical mineral deposits and reveal the impacts of crustal thickness and elevation changes on the development of the atmosphere, hydrosphere, and biosphere. However, a significant knowledge gap in reconstructing regional paleo-crustal thickness distribution is that most estimation proxies are limited to arc-related magmas. By mining extensive geochemical data from present-day subduction zones, collision orogenic belts, and non-subduction-related intraplate igneous rock samples worldwide, along with their corresponding Moho depths during magmatism, we have developed a machine learning-based mohometry linking geochemical data to Moho depth, which is universally applicable in reconstructing ancient orogenic systems’ paleo-crustal evolution and tracking complex tectonic histories in both spatial and temporal dimensions. Our novel mohometry model demonstrates robust performance, achieving an R² of 0.937 and RMSE of 4.3 km. Feature importance filtering highlights key geochemical proxies, allowing for accurate paleo-crustal thickness estimation even when many elements are missing. The mohometry validity is demonstrated through applications to southern Tibet, which has well-constrained paleo-crustal thicknesses, and the South China Block, which is noted for its complex tectonic evolution and extensive 800-km-wide Cretaceous extensional system. Additionally, the evolution of reconstructed paleo-crustal thickness, particularly in areas with anomalously thick crust, strongly correlates with porphyry ore deposits. These findings offer valuable insights for prospecting for new porphyry ore deposits, particularly in ancient orogens where significant surface erosion has occurred.

In this study, we present zircon U-Pb ages, Hf-O isotopes, and whole-rock geochemical data for the newly identified Duobaoshan appinite-granite suite in the eastern Central Asian Orogenic Belt (CAOB). Field and petrographic investigations show that this suite of rocks is composed of hornblende gabbro, quartz monzonite, and granite porphyry. The appinites are abnormally hornblende-rich, and contain spectacular hornblende phenocrysts, pegmatitic textures, and miarolitic cavity structures that indicate an anomalous water-rich origin. The quartz monzonite and granite porphyry show intrusive contact relations with the appinites. Secondary ion mass spectrometry (SIMS) zircon dating reveals that the Duobaoshan appinite-granite suite was emplaced in a very short time interval of 224–223 Ma. These samples show typical subduction related arc magmatic geochemical characteristics that are enriched in large-ion lithophile elements (LILEs) and light rare earth elements (REEs), depleted in high field strength elements (HFSEs) and middle and heavy REEs. All samples exhibit comparative total REEs and no significant evolutionary relationships. The appinites show high Sr/Y ratios (reaching ~100) and positive or zero Eu anomalies, which reveal amphibole fractionation promotion and plagioclase fractionation suppression in a water-rich magma system. The quartz monzonite possesses high Sr/Y and La/Yb ratios that exhibit adakite-like properties and were derived from thickened lower continental crust. The granite porphyry is silica-rich and non-adakitic. All samples have juvenile whole-rock initial 87Sr/86Sr ratios (~0.7038) and ɛNd(t) values. Zircons have depleted mantle-like ɛHf (t) (to +12.0) and δ18O (~+5.65‰) values. Combining these geochemical features with observations of the regional geology and tectonic setting, we propose that the Duobaoshan appinite-granite suite was generated under a Triassic back-arc extensional setting related to the southward subduction of the Mongol-Okhotsk Ocean. The appinites were derived from an unusual water-rich mantle source, which was previously metasomatized by slab-derived fluids. The quartz monzonite and granite porphyry were generated from partial melting of the juvenile lower continental crust triggered by coeval appinitic magma underplating.

We modify the Modified Cam-Clay (MCC) model for large stress ranges encountered in geological applications. The MCC model assumes that the friction angle (ϕ) and the slope of the compression curve (λ) of a mudrock are constant and thus predicts constant values for the lateral effective stress ratio under uniaxial, vertical strain (K0) and undrained strength ratio (S_u/(σ_v^’ )). However, experimental work shows that λ, ϕ, and S_u/(σ_v^’ ) decrease and K0 increases substantially with stress over large stress ranges (e.g., up to 100 MPa). We incorporate the stress dependency of λ and ϕ into the MCC model and use the new model to predict S_u/(σ_v^’ ) and K0 ratios. The modified model, with only one additional parameter, successfully predicts the stress dependency of these ratios. We encode the modified model and use it for finite-element analysis of a salt basin in the deepwater Gulf of Mexico. The stresses that the new model predicts around salt differ significantly from those predicted using the original model. We incorporate the stress dependency of the friction angle into the analytical models developed for critical tapers, wellbore drilling, and the stability of submarine channel levees. We show that the decrease of the friction angle with stress 1) results in a concave surface for critical wedges, 2) shifts the drilling window to higher mud weights and makes it narrower for a vertical wellbore, and 3) causes deep-seated failure of submarine channel levees at lower angles. Our study could improve in situ stress and pore pressure estimation, wellbore drilling, and quantitative understanding of geological processes.

Fourier spectra are powerful tools to analyse the scale behavior of turbulent flows. While such spectra are mathematically based on regular periodic data, some state-of-the-art ocean and climate models use unstructured triangular meshes. Observational data is often also available only in an unstructured fashion. In this study, scale analysis specifically for the output of models with triangular meshes is discussed and the representable wavenumbers for Fourier analysis are derived. Aside from using different interpolation methods and oversampling prior to the computation of Fourier spectra, we also consider an alternative scale analysis based on the Walsh--Rademacher basis, i.e. indicator functions. It does not require interpolation and can be extended to general unstructured meshes. A third approach based on smoothing filters which focus on grid scales is also discussed. We compare these methods in the context of kinetic energy and dissipation power of a turbulent channel flow simulated with the sea ice-ocean model FESOM2. One simulation uses a classical viscous closure, another a new backscatter closure. The latter is dissipative on small scales, but anti-dissipative on large scales leading to more realistic flow representation. All three methods clearly highlight the differences between the simulations as concerns the distribution of dissipation power and kinetic energy over scales. However, the analysis based on Fourier transformation is highly sensitive to the interpolation method in case of dissipation power, potentially leading to inaccurate representations of dissipation at different scales. This highlights the necessity to be cautious when choosing a scale analysis method on unstructured grids.

A method based on electron magnetohydrodynamics (EMHD) for the reconstruction of steady, two-dimensional plasma and magnetic field structures from data taken by a single spacecraft, first developed by Sonnerup et al. (2016), is extended to accommodate inhomogeneity of the electron density and temperature, electron inertia effects, and guide magnetic field in and around the electron diffusion region (EDR), the central part of the magnetic reconnection region. The new method assumes that the electron density and temperature are constant along, but may vary across, the magnetic field lines. We present two models for the reconstruction of electron streamlines, one of which is not constrained by any specific formula for the electron pressure tensor term in the generalized Ohm’s law that is responsible for electron unmagnetization in the EDR, and the other is a modification of the original model to include the inertia and compressibility effects. Benchmark tests using data from fully kinetic simulations show that our new method is applicable to both antiparallel and guide-field (component) reconnection, and the electron velocity field can be better reconstructed by including the inertia effects. The new EMHD reconstruction technique has been applied to an EDR of magnetotail reconnection encountered by the Magnetospheric Multiscale spacecraft on 11 July 2017, reported by Torbert et al. (2018) and reconstructed with the original inertia-less version by Hasegawa et al. (2019), which demonstrates that the new method better performs in recovering the electric field and electron streamlines than the original version.

Fluid migration in subduction zones is a key controlling factor of slow and megathrust earthquakes at plate boundaries. During the migration, seismic velocity and heterogeneous structures in its pathways may be temporarily varied, preferably triggering slow earthquakes. Here, we show that transient changes of seismic heterogeneity occurred 0-9 months before shallow slow earthquakes in the Nankai subduction zone, Japan, using very long-term (6–10 y) records of ambient seafloor noise. The heterogeneity changes preceding to shallow slow earthquakes were observed near the margin of the source region, while concurrent changes primarily occurred in the source region. We propose that the heterogeneity changes are attributed to dynamic fluid migration, and the difference in timings reflects the pore pressure level in the corresponding source region. When fluids are supplied to a source region under relatively low pressure, fluids are leaked out from its downdip or updip side, and slow earthquakes occur not immediately but with a time delay of at most 9 months. In the high pore pressure case, slow earthquakes occur immediately with fluid migration from the source region. This study suggests that the heterogeneous seismic structure is possibly changed by fluid migration before slow earthquakes in the Nankai subduction zone.

Nonmigrating tidal diagnostics of SABER temperature observations in the ionospheric dynamo region reveal a large amount of variability on time-scales of a few days to weeks. In this paper, we discuss the physical reasons for the observed short-term tidal variability using a novel approach based on Information theory and Bayesian statistics. We diagnose short-term tidal variability as a function of season, QBO, ENSO, and solar cycle and other drivers using time dependent probability density functions, Shannon entropy and Kullback-Leibler divergence. The statistical significance of the approach and its predictive capability is exemplified using SABER tidal diagnostics with emphasis on the responses to the QBO and solar cycle. Implications for F-region plasma density will be discussed.

It has been long known that the preferred crack alignments and fractures in rock cause seismic anisotropy and corresponding S-wave birefringence. Here the S-wave birefringence caused by the preferred alignment of cracks due to subcritical stress in the granitic basement of north central Oklahoma is examined. The data used for this study was collected during the IRIS Community Wavefields Experiment (CWE) in June and July of 2016, where more than 300 3-component (3-C) short-period seismographs were deployed in dense arrays with station spacings of 100m or less. These arrays were also in an area where many small earthquakes were occurring on a monthly basis, so that many were recorded by these arrays. The seismic data were cut from the original 30-day field records to produce short 3-C SEG-Y records of local earthquakes and explosions at a variety of back azimuths from the CWE array. Each 3-C record was rotated to the back azimuth of the source, such that the components become vertical, radial, and transverse with respect to the source. Vertical components are dominated by P arrivals, while radial components are dominated by SV arrivals and transverse components are dominated by SH arrivals. Seismic sections of the radial components of the array are then plotted in one color and overlain by the corresponding transverse components from the same array in another color. S-wave birefringence can then be directly observed as the time difference between arrivals, particularly first arrivals. S-wave birefringence is proof of seismic anisotropy and some characteristics of that anisotropy can be observed in record sections. For instance, birefringence is high along some azimuths and absent along other azimuths. Where birefringence is absent arrivals coincide, this could be either due to arrivals crossing or arrivals meeting but do not crossing. The latter case is important because it is the direction of an axis of symmetry for the anisotropic medium where the arrivals are propagating. This is also the case is observed in the record sections. The axis of symmetry observed in the record sections has an azimuth of 335 +/- 5 degrees. The fact that an axis of symmetry with no birefringence exists in the horizontal plane indicates that the anisotropic medium exhibits hexagonal symmetry, also known as horizontal transverse isotropy (HTI). It indicates that cracks and fractures are open perpendicular to the axis of symmetry and closed in other directions. Because of the large number of earthquakes occurring in this area a number of studies have been conducted on the in-situ stress orientations. In the sedimentary section overlaying the basement close to the CWE seismic array, borehole image logs indicate that the azimuth of drilling induced tensile fractures is 59 +/- 12 degrees. This is interpreted as the orientation of the maximum horizontal stress in the borehole. The axis of seismic anisotropy, which indicates the direction of minimum horizontal stress.

Radiation energy balance at the top of the atmosphere (TOA) is a critical boundary condition for the Earth climate. It is essential to validate it in the global climate models (GCM) on both global and regional scales. However, the comparison of overall radiation field is known to conceal compensating errors. Here we use a new set of radiative kernels to diagnose the radiation biases by different geophysical variables in the latest GCMs. We find although clouds remain a primary cause of radiation biases, the radiation biases caused by non-cloud variables are of comparable magnitudes. Many GCMs tend to have a cold bias in the air temperature and a moist bias in the tropospheric humidity, which lead to considerable biases in TOA radiation budget but are compensated by cloud biases. These findings signify the importance of validating the GCM-simulated radiation fields, with respect to both the overall and component radiation biases.

Assessment of spring snow cover fraction (SCF) can be valuable for understanding the efficacy of certain Earth system models (ESMs) in simulating the energy exchange between land and atmosphere system, global hydrological cycle and future climate impacts. In this work, we studied the model performance of 23 and 20 ESMs participating CMIP5 and CMIP6 by comparing satellite data from National Oceanic and Atmospheric Administration and National Climatic Data Center (NOAA/NCDC) over the Northern Hemisphere (NH) and its 13 sub-regions and further evaluating potential model improvement from CMIP5 to CMIP6. We found that the mean annual spring SCF that was simulated by CMIP5 and CMIP6 models was underestimated in most of the NH and overestimated on the Tibetan Plateau and in eastern Asia, and most of the model simulations showed a stronger reduction trend as well as an underestimated monthly climatological SCF. However, compared with those in CMIP5, most of the model simulations in CMIP6 had an improved ability to simulate spring SCF in terms of the annual mean, long-term trend and intra-annual variability. We also confirmed that the multi-model ensemble mean (MME) is a better way to represent the three aspects of spring SCF than most individual model simulations. The spring SCF values predicted by the CMIP5 and CMIP6 MMEs over the NH and its 13 sub-regions under different scenarios showed decreasing trends. The decreasing spring SCF trends differed under different scenarios, and the SCF under high emissions scenarios (RCP 8.5 and SSP5-8.5) continued to decrease.

The Arctic stratospheric polar vortex is an important driver of winter weather and climate variability and predictability in North America and Eurasia, with a downward influence that on average projects onto the North Atlantic Oscillation (NAO). While tropospheric circulation anomalies accompanying anomalous vortex states display substantial case-by-case variability, understanding the full diversity of the surface signatures requires larger sample sizes than those available from reanalyses. Here, we first show that a large ensemble of seasonal hindcasts realistically reproduces the observed average surface signatures for weak and strong vortex winters and produces sufficient spread for single ensemble members to be considered as alternative realizations. We then use the ensemble to analyze the diversity of surface signatures during the 25% weakest and strongest vortex winters. Over Eurasia, only one of three weak vortex clusters yields continent-wide cold conditions, suggesting that the observed Eurasian cold signature could be artificially strong due to insufficient sampling. For both weak and strong vortex cases, the canonical temperature pattern in Eurasia only clearly arises when North Atlantic sea surface temperatures exhibit the tripolar structure in-phase with the NAO. Over North America, while the main driver of interannual winter temperature variability is the El Nino;Southern Oscillation (ENSO), the stratosphere can modulate ENSO teleconnections, affecting temperature and circulation anomalies over North America and downstream. These findings confirm that anomalous vortex states are associated with a broad spectrum of surface climate anomalies on the seasonal scale, which may be obscured by the small observational sample size.