Zebra rocks, characterized by their striking reddish-brown stripes, rods, and spots of hematite (Fe-oxide), showcase complex self-organized patterns formed under far-from-equilibrium conditions. Despite their recognition, the underlying mechanisms remain elusive. We introduce a novel advection-dominated phase-field model that effectively replicates the Liesegang-like patterns observed in Zebra rocks. This model leverages the concept of phase separation, a well-established principle governing Liesegang phenomena. Our findings reveal that initial solute concentration and fluid flow velocity are critical determinants in pattern selection and transition. We quantitatively explain the spacing and width of a specific Liesegang-like pattern category. Furthermore, the model demonstrates that vanishingly low initial concentrations promote the formation of oblique patterns, with inclination angles influenced by rock heterogeneity. Additionally, we establish a quantitative relationship between band thickness and geological parameters for orthogonal bands. This enables the characterization of critical geological parameters based solely on static patterns observed in Zebra rocks, providing valuable insights into their formation environments. The diverse patterns in Zebra rocks share similarities with morphologies observed on early Earth and Mars, such as banded iron formations and hematite spherules. Our model, therefore, offers a plausible explanation for the formation mechanisms of these patterns and presents a powerful tool for deciphering the geochemical environments of their origin.

The coupling between the magnetosphere and solar wind contributes to the energy, momentum, and mass transfer between the systems. However, geomagnetic pulsations facilitate the continuation of this process in the magnetosphere and the production of discrete auroral arcs. Therefore, remote-sensing the magnetospheric conditions. Data analytics with machine learning (ML) gives insight into scalability, adaptability, and feature extraction compared to traditional empirical models. The availability of big data in the Svalbard network spanning 25years from 1996 motivated the current study. Hence, we present the forecasting of auroral Pc5 pulsations from solar wind parameters using the ML technique. In the training phase, there was a regression of 0.75 and MSE=11.90 nT2. The relationship between Pc5 forecast and observations in low and high geomagnetic activity and solar activity showed good consistency with R=0.76 and MSE= 11.4 nT2. For instance, the model adapted well to the St. Patrick geomagnetic storm of March 17th, 2015 despite uncertainties in the data. In addition, the model also adapted well with stunning performance in all Svalbard observatories with HOP leading with 6949 prediction events and NAL with the least. Thus, this was consistent with previous studies in terms of Pc5 pulsations latitudinal or L-shell dependence. Finally, validation with Kp and F10.7 indices presented excellent coherence between the models. Overall, The ML studied the connection between solar wind and interplanetary magnetic field properties to the ground magnetic field perturbations with good correlation results. Hence, the model will be fit for use by the magnetospheric community for space weather studies.

The pattern of surface warming plays a significant role in the Earth’s response to radiative forcing as it influences climate feedbacks. Distinct patterns of surface warming lead to divergent equilibrium and transient responses to identical forcing, emphasizing the need to analyse this pattern effect. While existing studies have primarily focused on assessing the influence of surface warming patterns on long-term warming (equilibrium climate sensitivity, committed warming), their role on the transient global warming remains poorly understood. Here, we introduce a novel analytical method to quantify the importance of evolving surface warming patterns on transient global warming. Our approach involves explicitly separating the radiative response caused by the global surface warming from the additional response induced by changing surface temperature patterns in the global energy budget. Using this new energy balance model, we assess the relative contribution of the radiative response induced by changing surface temperature patterns to global warming in idealized forcing experiments (1pctCO2) from 12 CMIP6 models. We show that the pattern effect consistently dampens global warming in 11 out of 12 model at decadal time scales. Specifically, we quantify that the transient climate response is reduced on average by 11% because of changing warming patterns. Our study demonstrates that distinct models exhibit significantly divergent transient global warming solely due to variations in the pattern effect. Overall, our results highlight the importance of changing warming patterns, through the pattern effect, in influencing decadal-scale transient warming. These findings support recent suggestions to incorporate warming pattern uncertainties in future climate projections.

Seismic and geodetic observations show that slow slip events (SSEs) in subduction zones can happen at all temporal and spatial scales and propagate at various velocities. Observation of rapid tremor reversals (RTRs) indicates back-propagating fronts traveling much faster than the main rupture front. Heterogeneity of fault properties, such as fault roughness, is a ubiquitous feature often invoked to explain this complex behavior, but how roughness affects SSEs is poorly understood. Here we use quasi-dynamic seismic cycle simulations to model SSEs on a rough fault, using normal stress perturbations as a proxy for roughness and assuming rate-and-state friction, with strengthening behavior at high slip rate. SSEs exhibit temporal clustering, large variations in rupture length and propagation speed, and back-propagating fronts at different scales. We identify a mechanism for back propagation: as ruptures propagate through low-normal stress regions, a rapid increase in slip velocity combined with rate-strengthening friction induces stress oscillations at the rupture tip, and the subsequent ”delayed stress drop’ induces secondary back-propagating fronts. Moreover, on rough faults with fractal elevation profiles, the transition from pulse to crack can also lead to the re-rupture of SSEs due to local variations in the level of heterogeneity. Our study provides a possible mechanism for the complex evolution of SSEs inferred from geophysical observations and its link to fault roughness.

Land reclamations influence the morphodynamic evolution of estuaries and tidal basins, because altered planform changes tidal dynamics and associated residual sediment transport. The morphodynamic response time to land reclamation is long, impacting the system for decades to centuries. Other human interventions (e.g., deepening of fairways or port construction) add a morphodynamic adaptation timescale to a system that may still adapt as the result of land reclamations. Our understanding of the cumulative effects of anthropogenic interference with estuaries is limited, because observations usually do not cover the complete morphological adaptation period. We aim to assess the impact of land reclamation works and other human interventions on an estuarine system by means of digital reconstructions of historical morphologies of the Ems Estuary over the past 500 years. Our analysis demonstrates that the intertidal-subtidal area ratio altered due to land reclamation works and that the ratio partly restored after land reclamation ended. The land reclamation works have led to the degeneration of an ebb- and flood channel system, transitioning the estuary from a multichannel to a single-channel system. We infer that the 20th-century intensification of channel dredging and re-alignment works accelerated rather than cause this development. The centennial-scale observations suggest that estuarine systems responding to land reclamations follow the evolutionary trajectory predicted by tidal asymmetry-based stability theory as they move towards a new equilibrium configuration with modified tidal flats and channels. Existing estuarine equilibrium theory, however, fails in linking multichannel stability to the loss of intertidal area, emphasizing the need for additional research.

Low Earth orbit (LEO) radio occultation (RO) constellations can provide global electron density profiles (EDPs) to better specify and forecast the ionosphere-thermosphere (I-T) system. To inform future RO constellation design, this study uses comprehensive Observing System Simulation Experiments (OSSEs) to assess the ionospheric specification impact of assimilating synthetic EDPs into a coupled I-T model. These OSSEs use 10 different sets of RO constellation configurations containing 6 or 12 LEO satellites with base orbit parameter combinations of 520 km or 800 km altitude, and 24 degrees or 72 degrees inclination. The OSSEs are performed using the Ensemble Adjustment Kalman Filter implemented in the Data Assimilation Research Testbed and the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). A different I-T model is used for the nature run, the Whole Atmosphere Model-Ionosphere Plasmasphere Electrodynamics (WAM-IPE), to simulate the period of interest is the St. Patrick’s Day storm on March 13-18, 2015. Errors from models and EDP retrieval are realistically accounted for in this study through distinct I-T models and by retrieving synthetic EDPs through an extension Abel inversion algorithm. OSSE assessment, using multiple metrics, finds that greater EDP spatial coverage leading to improved specification at altitudes 300 km and above, with the 520 km altitude constellations performing best due to yielding the highest observation counts. A potential performance limit is suggested with two 6-satellite constellations. Lastly, close examination of Abel inversion error impacts highlights major EDP limitations at altitudes below 200 km and dayside equatorial regions with large horizontal gradients and low electron density magnitudes.

A document by Karen An. Click on the document to view its contents.

Convective dissolution of CO2 is a well-known mechanism in geological storage of CO2 . It is triggered by gravitational instability which leads to the onset of free convection. The phenomenon is well studied in porous media, such as saline aquifers, and the literature provides substantial evidence that onset times and effective flux rates can be estimated based on a characterization of instabilities that uses the Darcy velocity. This work extends the study of convective dissolution to open water-filled fractures, where non-Darcy regimes govern the induced flow processes. Numerical simulations using a Navier-Stokes model with fluid density dependent on dissolved CO2 concentration were used to compute scenario-specific results for effective CO2 entry rates into an idealized fracture with varying aperture, temperature, and CO2 concentration at the gas-water interface. The results were analyzed in terms of dimensionless quantities. They revealed a Rayleigh invariance of the effective CO2 flux after the complete formation of a quasi-stationary velocity profile, i.e. after a certain entry length. Hence, this invariance can be exploited to estimate the effective CO2 entry rates, which can then be used, in perspective, in upscaled models. We have studied convective CO2 dissolution for two different fracture settings; the first one relates to karstification scenarios, where CO2 is the dominant driving force, and were stagnant-water conditions in fractures have not yet received attention to date. The second setting is inspired from geological CO2 storage, where the literature provides only studies on convective CO2 dissolution for porous-media flow with Darcy regimes.

A document by Zixuan Zhou. Click on the document to view its contents.

Tree-ring series from ENSO rainfall impact regions reconstruct the tropical Pacific SST field with a high degree of skill back to 1100 CE. 2. Two very different reconstruction methods produce similar results and each can only reconstruct the leading EOF mode of SST variability. 3. Reconstructions extending back 1100 CE do not reveal any clear increase in El Niño variability, but do show a recent overall SST warming.

Peak glacial-to-Heinrich-1 changes in Denmark Strait Overflow and seawater stratification in the Nordic Seas, a switchboard of changes in Atlantic Meridional Overturning Circulation and the ’Nordic Heat Pump’Michael Sarnthein1) and Patrick Blaser2)1) Institut für Geowissenschaften, University of Kiel, D-24118 Kiel, Germany

A document by Bhupendra Bahadur Singh. Click on the document to view its contents.

Tropical cyclones bring health risks and can trigger outbreaks of diarrheal diseases in affected populations. There are several reviews that mention the relationship between tropical cyclones and diarrheal diseases. However, there is no dedicated review of the current evidence and extent of research on the association between tropical cyclones and diarrheal diseases. We performed a scoping review to thoroughly examine the available literature. We also thematically analyzed the transmission pathways explained in the literature. A total of 96 studies were included. Twenty-three studies quantitatively measured the tropical cyclone--diarrhea associations, with half reporting positive associations. We found that the studies defined and measured tropical cyclone exposure differently and mostly analyzed a single event. The study designs employed were mostly pre-post comparisons that had several limitations affecting internal validity. These differences also prevent the quantitative pooling of evidence. A standardized approach to measuring the association between tropical cyclones and diarrheal diseases can be devised by suggesting the most appropriate exposure definition and modeling.

Characterizing fault behaviors prior to large earthquakes through long-term seismicity is crucial for seismic hazard assessment, yet constructing high-resolution catalogs over extended periods poses significant challenges. This study introduces LoSAR, a novel deep learning-driven workflow that enhances phase picking by Localizing a Self-Attention Recurrent neural network with local data, addressing the generalization problem common in data-driven approaches. We apply LoSAR to two distinct regions that are both featured by recent large earthquakes: (1) preseismic period of the Ridgecrest-Coso region (2008-2019), and (2) pre-postseismic period of the East Anatolian Fault Zone (EAFZ, 2020-2023/04). Through detailed comparisons, we demonstrate that LoSAR offers slightly higher detection completeness than the QTM matched filter catalog, while boosts an over 100 times faster processing and a superior temporal stability, avoiding low-magnitude gaps during background periods. Against PhaseNet and GaMMA, two established phase picker and associator, LoSAR proves more scalable and generalizable, achieving roughly 2.5 times more event detections in the EAFZ case, along with a ~7 times higher phase association rate. By leveraging the two enhanced catalogs and b-value analysis, we gain insights into the preseismic fault behaviors: (1) The Ridgecrest faults are characterized by sparse and distributed seismicity across a band of ~20 km, revealing multiple orthogonal preexisting faults; coupled with a low b-value that signifies this area as a persistent asperity; (2) The Erkenek-Pütürge segment of EAFZ exhibits complex fault geometry that forms a persistent rupture barrier, which consists of a hidden conjugate fault system that presents as a ~10-km wide fault zone.

The tectono-stratigraphic development of continental basins is key to our understanding of the location and scale of metal deposits required by the energy transition. We examine the Neo-proterozoic Katangan copper basin of Central Africa to determine the link between lithosphere and crust and the generation of potential fluid pathways. Integration of lithospheric thickness, quantitative basin analysis and structure, defines a basin scale tectono-stratigraphic model for controls on potential fluid pathways. The basin developed along the thinned (140-170 km thick) margins of the Congo, Kalahari and Bangweulu cratons. Crustal scale fault zones define these margins and imply a mechanical weakness in the basin. Drill core and seismic data show extensional, half graben geometries. Basin subsidence analysis indicates two phases of rift-driven subsidence and increasing lithospheric extension from the basin boundary to a Central Rift Zone (CRZ). The CRZ also maps out as a sediment provenance boundary. Subsequent Late Ediacaran and Cambrian orogenesis and rift-fault inversion occurred most intensively within the CRZ. Basin expulsion and thrust tectonics resulted in a narrow belt of crustal thickening defined today by a ~50 km wide zone of garnet amphibolite facies metamorphism. The spatial coincidence of early crustal extension, relatively thin lithosphere, and later intense basin inversion along the CRZ, indicates that pre-existing crustal structure and weakness was a key tectonic control. The reactivated structures define several tectonic domains, control basin architecture within the zones and occur as potential fluid pathways for high volume fluid migration for metal bearing brines.

Natural porous media is generally heterogeneous and anisotropic. The structure of porous media plays a vital role and is often the source of the heterogeneity and anisotropy. In physical processes such as fluid flow in porous media, a small number of major features, here referred to as wide channels, are responsible for the majority of the flow. The thickness and orientation of these channels often determine the permeability characteristics. Typically, the identification of such major features is conducted through time-consuming and expensive simulations. Here we propose a prompt approach based on geometric properties derived from three-dimensional (3D) images. The size or radius of the major features is obtained via distance maps, and their orientations are determined by Principal Component Analysis. Subsequently, we visualize these features with color and color brightness according to their orientation and size, together with their location and distribution in 3D space. The simultaneous visualization of anisotropy (orientation) and heterogeneity (size) in one plot provides a straightforward way to enhance our understanding of pore structure characteristics. Besides, we propose a refined stereographic projection method to statistically illustrate both heterogeneity and anisotropy. Based on these insights, we further present a new way to compress the model size in numerical simulation, therefore significantly reducing the computational cost, while retaining its essential characteristics.

The Arabian Gulf (AG) exports hypersaline, dense waters into the Sea of Oman (SOO), replaced by fresher inflowing surface waters from the Indian Ocean. We investigate the impact of recent AG warming on its exchange with the SOO and the implications this has on the AG biogeochemistry. Using an eddy-resolving hindcast model simulation, we analyze the hydrography and biogeochemistry of the AG and the SOO from 1980 to 2018. Our study reveals that changes in summer surface winds have accelerated AG warming and weakened it in the SOO, reducing the density gradient and water exchange between the two seas during late summer. This has led to nutrient buildup, increased productivity, and heightened deoxygenation and acidification in the AG. These findings underscore how subtle wind changes can exacerbate the vulnerability of marginal seas to climate change and stress the need to properly represent regional winds in global climate models.

Idealized general circulation models (GCMs) suggest global-mean precipitation ceases to increase with warming in hot climates. However, it is unclear if this occurs in more comprehensive GCMs. Here, we examine precipitation over a wide range of climates simulated with comprehensive GCMs. We find that in the Community Atmosphere Model, global-mean precipitation increases approximately linearly with global-mean surface temperatures up to about 330~K, where it peaks at 5~mm~day$^{-1}$. Beyond 330~K, global-mean precipitation decreases substantially despite increasing surface temperatures. This occurs because of increased atmospheric shortwave absorption from water vapor, which limits shortwave radiation available for surface evaporation. Precipitation decreases in the tropics and subtropics, but continues to increase in the extratropics due to increased poleward moisture transport. Precipitable water increases everywhere, resulting in longer water-vapor residence times and implying more episodic precipitation. Other GCMs indicate global-mean precipitation might exhibit a smaller maximum rate and begin to decrease at lower surface temperatures.