The primary data sources for reconstructing the geomagnetic field of the past millennia are archaeomagnetic and sedimentary paleomagnetic data. Sediment records, in particular, are crucial in extending the temporal and spatial coverage of global geomagnetic field models, especially when archaeomagnetic data is sparse. However, the post-depositional detrital remanent magnetization (pDRM) process is still poorly understood and can cause smoothing of the magnetic signal and offsets with respect to the sediment age. To make effective use of sedimentary data, it is essential to understand the lock-in process and its impact on the magnetic signal. In this study, we investigate the lock-in process theoretically and derive a parameterized lock-in function that can approximate possible lock-in behaviors. Additionally, we demonstrate that a lock-in function that is independent of absolute parameters can only be applied to the magnetic direction components (declination and inclination), but not to the relative intensity. Integrating this lock-in function into the ArchKalmag14k modeling procedure \cite{schanner2022archkalmag14k} allows including data from sediment records. The parameters of the lock-in function are estimated by the maximum likelihood method using archaeomagnetic data as a reference. The effectiveness of the proposed method is evaluated through synthetic tests. Additionally, we apply our technique to sediment records from two lakes in Sweden (Kälksjön and Gyltigesjön) as first case studies. Our results demonstrate that the proposed method is capable of effectively correcting the distortion caused by the lock-in process, making data from sedimentary records a more reliable and informative source for geomagnetic field reconstructions.

The field of MultiSector Dynamics (MSD) explores the dynamics and co-evolutionary pathways of human and Earth systems with a focus on critical goods, services, and amenities delivered to people through interdependent sectors. This commentary lays out core definitions and concepts, identifies MSD science questions in the context of the current state of knowledge, and describes ongoing activities to expand capacities for open science, leverage revolutions in data and computing, and grow and diversify the MSD workforce. Central to our vision is the ambition of advancing the next generation of complex adaptive human-Earth systems science to better address interconnected risks, increase resilience, and improve sustainability. This will require convergent research and the integration of ideas and methods from multiple disciplines. Understanding the tradeoffs, synergies, and complexities that exist in coupled human-Earth systems is particularly important in the context of energy transitions and increased future shocks.

Solar, auroral, and radiation belt electrons enter the atmosphere at polar regions leading to ionization and affecting its chemistry. For example particle-produced OH and NO molecules affect the ozone content in the middle atmosphere. Climate models usually parametrize this ionization and the related changes in chemistry based on satellite particle measurements. Precise measurements of the particle and energy influx into the upper atmosphere are difficult because they vary substantially in location and time. Widely used particle data are derived from the POES and GOES satellite measurements which provide electron and proton spectra. We present electron energy and flux measurements from the Special Sensor Ultraviolet Spectrographic Imagers (SSUSI) satellite instruments. This formation of satellites observes the auroral zone in the UV from which electron energies and fluxes are inferred. We use these observed electron energies and fluxes to calculate ionization rates and electron densities in the mesosphere and lower thermosphere (≈ 40–200 km). We also present an initial comparison of these rates to other models and compare the electron densities to those measured by the EISCAT radar. Together with photochemical models, trace gas concentrations, for example of NO, can be calculated from these electron densities. These concentrations then provide an independent source for comparing and validating satellite trace gas measurements.

Vertical motions of Earth’s surface are used to inform almost all branches of the Earth Sciences, and central role in understanding geological, biological and climatic processes. An important challenge is generating enough information to reliably constrain histories of vertical motion. Significant effort has been expended in generating information about denudation (e.g. from thermochronometry), uplift (e.g. from stable isotopes or drainage analyses) and subsidence patterns. However, a canonical inventory of measurements that determine continental uplift on timescales pertinent to growth and decay of continental topography does not exist. We address this issue using the distribution of unequivocally marine rock recorded in new, detailed, paleobiological inventories. We show that these new compilations of paleobiological and paleoenvironmental data, that were generated to address paleobiological problems, also provide an unprecedented number of self-consistent, high-resolution measurements of continental and ocean island uplift. We focus on the Cretaceous to Recent history, which captures the large-scale marine incursions of the continents. Our results highlight that significant improvements can be made in understanding the histories of the continents in using these measurements of uplift. We present examples from North and South America, southern Africa and Australia to show how this new database can be explored to better understand the processes that generate high topography. They emphasize the importance of large inventories of paleobiological data for understanding long-wavelength uplift and the role tectonic and mantle convective processes play in generating continental topography.

Numerous recent studies found significant correlations between weakening of the Gulf Stream (GS) and rising coastal sea level (CSL) along the U.S. East Coast. Based on monthly altimeter data and Florida Current transport, Chi et al. (2023; here, CH23) argued that geostrophic adjustment of the GS is unlikely to drive variations in CSL in the Mid-Atlantic Bight (MAB). It is argued here that this conclusion cannot be universally applicable to all cases, since the monthly data disregard correlations previously found for short time scales based on hourly and daily data; the impact of GS variability on time scales of decades and longer as well as potential time lags between the GS and CSL variability were also not considered by CH23. Examples are given here to demonstrate the important role of the GS in post hurricane coastal flooding.

The development of parameterizations is a major task in the development of weather and climate models. Model improvement has been slow in the past decades, due to the difficulty of encompassing key physical processes into parameterizations, but also of calibrating or â\euro˜tuningâ\euro™ the many free parameters involved in their formulation. Machine learning techniques have been recently used for speeding up the development process. While some studies propose to replace parameterizations by data-driven neural networks, we rather advocate that keeping physical parameterizations is key for the reliability of climate projections. In this paper we propose to harness machine learning to improve physical parameterizations. In particular we use Gaussian process-based methods from uncertainty quantification to calibrate the model free parameters at a process level. To achieve this, we focus on the comparison of single-column simulations and reference large-eddy simulations over multiple boundary-layer cases. Our method returns all values of the free parameters consistent with the references and any structural uncertainties, allowing a reduced domain of acceptable values to be considered when tuning the 3D global model. This tool allows to disentangle deficiencies due to poor parameter calibration from intrinsic limits rooted in the parameterization formulations. This paper describes the tool and the philosophy of tuning in single-column mode. Part 2 shows how the results from our process-based tuning can help in the 3D global model tuning.

We develop a rate- and state-dependent friction (RSF) model to investigate a compendium of recent experiments performed in the laboratory. In the documented experiments, a fault was sheared until macroscopic stick-slip frictional failure. Before macro-failure, small precursor seismicity nucleated from regions that also experienced aseismic slow slip. This behavior requires heterogeneity and is defined in our model as local variation in frictional parameters inferred from the roughness. During sliding wear introduced a smooth-polished surface onto a previously rough surface and was quantified using a bimodal Gaussian distribution of surface heights. We used spatial distribution of the smooth and rough sections to impose binary partitioning in critical slip distance $D_{c}$ to a planar frictional model. Simulations revealed that local seismicity nucleated on the “smooth’ sections, while the larger “rough’ section hosted aseismic slip. As the level of heterogeneity between smooth and rough sections increased, the model transitioned from a predominantly stick-slip to creeping. The simulations produced a dominant asperity, which appeared to control aspects of rupture nucleation: ($i$) weak heterogeneity caused the dominant asperity to generate foreshocks but also “ignite’ cascade-up fault-wide event, while ($ii$) strong heterogeneity led to constrained repeaters. Seismic source properties: average slip $\delta$, seismic moment $M_{0}$, stress drop $\Delta \tau$ and fracture energy $G^{’}$, were determined for each event and agreed with separate kinematic estimates made independently from seismic measurements. Our numerical calculations provide insight into rate-dependent cascade-up nucleation theory where frictional heterogeneity here was associated with wear of solid frictional contacts in the laboratory.

The simultaneous occurrence of extremely wet winters at multiple locations in the same region can contribute to widespread flooding and associated socio-economic losses. However, the change in the spatial extent of precipitation extremes is largely overlooked in climate change assessments. Employing new multi-thousand-year climate model simulations, we show that under both 2.0°C and 1.5°C warming scenarios, wintertime precipitation extreme extents would increase over about 80-90% of the Northern Hemisphere. Stabilising at 1.5°C rather than 2°C would reduce the average magnitude of the increase by 1.6-2 times. According to the climate model, the increased extents are caused by increases in precipitation intensity increasing rather than changes in the spatial organisation of the events. Relatively small percentage increases in precipitation intensities (e.g., by 4%) can drive disproportionately larger, by 1-2 orders of magnitude, growth in the spatial extents (by 97%).

The driving processes responsible for producing the Central Atlantic Magmatic Province, the Large Igneous Province associated with end-Triassic rifting of Pangea, remain largely debated. Because their compositions encompass most of the Central Atlantic basalt spectrum, tholeiites from southern Eastern North America are considered pivotal for identifying magma origins. New 176Hf/177Hf measurements for 201 Ma Eastern North American tholeiites dominantly record a local petrogenetic history. Their εHf ratios, corrected to an emplacement age of 201 Ma (-7.85 to +5.86), form a positive but shallowly sloped array slightly deviating from the terrestrial array on a εHf vs. εNd diagram. Comparison of 176Hf/177Hf to other isotope ratios and trace elements helps to rule out several petrogenetic scenarios, particularly mixing of melts from global depleted or enriched mantle components. In contrast, partial melting of subduction-metasomatized mantle can explain the parental magma composition for southern Eastern North America. Such metasomatism likely occurred during Paleozoic subduction around Pangea and may have been dominated by sediment-derived fluid reactions. The observed 176Hf/177Hf vs. 143Nd/144Nd array may reflect subsequent assimilation of lower continental crust, perhaps together with limited direct melting of recycled continental crust in the asthenosphere. The proposed recycling scenario does not specifically support or preclude a mantle plume origin for the Central Atlantic Magmatic Province, but instead points toward the presence of a distinct local mantle source and crustal assimilation processes during magma transport. Detailed understanding of these local effects is needed in order to more accurately understand the origins of Large Igneous Provinces.

Processes that facilitate the transition between continental rifting and sea-floor spreading remain unclear. Variations in the spatial distribution of extension through Afar and into the Red Sea are indicative of temporal evolution of the rift. We develop a time series of Sentinel-1 interferometric synthetic aperture radar (InSAR) observations of ground deformation covering the whole Afar Rift from 2014-2019, to study the distribution of extension across all magmatic segments. By incorporating GNSS observations, we resolve 3D average velocities in the vertical, rift-perpendicular, and rift-parallel directions. Results show the spatial distribution of long-term plate motions over the rift, as well as deformation at individual volcanic centres, including Dallol, Nabro, and Erta ’Ale. We find that in northern and central Afar, the majority of extension is accommodated within +/- 15-30 km of magmatic spreading centres. In southern Afar, near the Nubia-Arabia-Somalia triple-junction, extension is distributed over 90-180 km, which may indicate an increase in rift focussing with rift maturity. We also observe rapid surface uplift and rift-perpendicular extension at the Dabbahu-Manda-Hararo segment with velocities of 33 +/- 4 mm/yr and 37 +/- 4 mm/yr respectively. These are higher than the background extension rate of 18-20 mm/yr, but have decreased by 55-70 % since 2006-10. The data suggests that this is due to an on-going long-lived response to the 2005-10 rifting episode, with potential continued processes below the segment including a lower-crustal viscous response and magma movement. Continued long-term observations of surface deformation provide key constraints on tectono-magmatic processes in Afar.

The unprecedented spatiotemporal resolution of the sixty-four dual electron and ion spectrometers comprising the Fast Plasma Investigation (FPI) onboard the four Magnetospheric Multiscale (MMS) spacecraft enables us to compute terms of the Vlasov equation and thus compare MMS measurements directly to kinetic theory. Here we discuss our techniques for determining spatial and velocity-space gradients of the ion and electron distribution function from the skymaps provided by FPI. We present initial results validating and comparing the contributions from ∂f/∂t, v·∇f, and a·∇vf for a variety of kinetic plasma contexts including both reconnection and non-reconnection events, such as electron diffusion regions (EDRs), magnetic holes, and thin electron-scale current sheets. The ability to resolve gradients of the distribution function motivates comparison of MMS observations to predictions from gyro-kinetic theory and particle-in-cell (PIC) simulations as an approach for determining which physical mechanism is responsible for generating ion and electron crescent distributions observed in association with EDRs and thin boundary layers.

Water supply reliability in the Truckee River basin stands to substantially benefit from forecast-informed reservoir operations(FIRO), especially given expected increases in rain: snow ratios and a transition to earlier runoff under warming climate that current infrastructure and operational rules were not designed for. However, in its position on the lee side of the Sierra Nevada mountains (CA/NV, USA), several unique forecast uncertainties exist that must be considered to mitigate against increased flood risk potential. Both water supply and floods are strongly linked to wintertime atmospheric rivers (AR) but despite improvements in forecasting these events at long lead times, the timing and amount of spillover precipitation onto the lee side remains a key uncertainty. In addition, storm runoff volumes in this basin are highly sensitive to rain-snow elevation, which is also difficult to forecast. Finally, antecedent snowpack and soil conditions have the potential to modulate runoff volumes but factors controlling the strength of these modulations are incompletely understood and monitored. In this study, we assess streamflow forecast skill in the Truckee River to provide a preliminary understanding of potential forecast-related challenges and opportunities for FIRO. To accomplish this, we used an archive of readily available short-range Hydrologic Ensemble Forecast System winter (Oct-Apr) streamflow forecasts for water years 2015-2020 and compared these to observed3-day flows at lead times of 0 to 15 days. We subset the data into AR days, non-AR days and top 10% flow days examined the variance explained between the ensemble median and observed 3-day flows as a function of lead time. We also examined how the observed 3-day flows rank in relation to the ensemble members for each day. We found that forecast accuracy improves considerably starting at a 7-day lead time but tends to be lower for high-flow and AR events relative to non-ARs. We also found the ensembles to have a slight bias toward underprediction and tendency toward under-dispersion (i.e. observed flows were sometimes outside the ensemble range) with this being the case for AR and high flow days for some but not all sites.

A document by Christopher B Marsh. Click on the document to view its contents.

Exotic plant invasions alter ecosystem properties and threaten ecosystem functions globally. Interannual climate variability (ICV) influences both plant community composition (PCC) and soil properties, and interactions between ICV and PCC may influence nitrogen (N) and carbon (C) pools. We asked how ICV and non-native annual grass invasion covary to influence soil and plant N and C in a semiarid shrubland undergoing widespread ecosystem transformation due to invasions and altered fire regimes. We sampled four progressive stages of annual grass invasion at 20 sites across a large (25,000 km2) landscape for plant community composition, plant tissue N and C, and soil total N and C in 2013 and 2016, which followed two years of dry and two years of wet conditions, respectively. Multivariate analyses and ANOVAs showed that in invasion stages where native shrub and perennial grass and forb communities were replaced by annual grass-dominated communities, the ecosystem lost more soil N and C in wet years. Path analysis showed that high water availability led to higher herbaceous cover in all invasion stages. In stages with native shrubs and perennial grasses, higher perennial grass cover was associated with increased soil C and N, while in annual-dominated stages, higher annual grass cover was associated with losses of soil C and N. Also, soil total C and C:N ratios were more homogenous in annual-dominated invasion stages as indicated by within-site standard deviations. Loss of native shrubs and perennial grasses and forbs coupled with annual grass invasion may lead to long-term declines in soil N and C and hamper restoration efforts. Restoration strategies that use innovative techniques and novel species to address increasing temperatures and ICV and emphasize maintaining plant community structure – shrubs, grasses, and forbs – will allow sagebrush ecosystems to maintain C sequestration, soil fertility and soil heterogeneity.

Rocks around the InSight lander were measured in lander orthoimages of the near field (<10 m), in panoramas of the far field (<40 m), and in a high-resolution orbital image around the lander (1 km2). The cumulative fractional area versus diameter size-frequency distributions for four areas in the near field fall on exponential model curves used for estimating hazards for landing spacecraft. The rock abundance varies in the near field from 0.6% for the sand and pebble rich area to the east within Homestead hollow, to ~3-5% for the progressively rockier areas to the south, north and west. The rock abundance of the entire near field is just over 3%, which falls between that at the Phoenix (2%) and Spirit (5%) landing sites. Rocks in the far field (<40 m) that could be identified in both the surface panorama and a high-resolution orbital image fall on the same exponential model curve as the average near field rocks. Rocks measured in a high-resolution orbital image (27.5 cm/pixel) within ~500 m of the lander that includes several rocky ejecta craters fall on 4-5% exponential model curves, similar to the northern and western near field areas. As a result, the rock abundances observed from orbit falls on the same exponential model rock abundance curves as those viewed from the surface. These rock abundance measurements around the lander are consistent with thermal imaging estimates over larger pixel areas as well as expectations from fragmentation theory of an impacted Amazonian/Hesperian lava flow.

The Cabled Observatory Vent Imaging Sonar (COVIS) was initially installed on the Ocean Observatories Initiative’s Cabled Array (OOI-CA) observatory at ASHES hydrothermal vent field on Axial Seamount in July 2018. COVIS recorded the acoustic backscatter from the water-column plumes formed above hydrothermal sources and the seafloor within the sonar’s field-of-view until Oct 2018, when an instrument malfunction suspended regular data-collection procedures. In July 2019, COVIS was redeployed after repairs and has since been collecting data at full capacity. Here, we present a comprehensive analysis of the acoustic backscatter data recorded by COVIS along with the in-situ temperature measurements in 2018 and 2019. The results demonstrate significant influences of ocean tides and bottom currents on diffuse hydrothermal discharge within ASHES. In addition, comparison with local seismicity shows a positive correlation between diffuse hydrothermal venting and the seismic activity in the vicinity of the vent field, which provides evidence for an intimate connection between hydrothermal activity and geological processes during the dynamic period leading up to the next eruption of Axial Seamount. Overall, our results showcase the capabilities of underwater acoustic techniques as remote-sensing tools for long-term, quantitative monitoring of seafloor hydrothermal discharge.

Although it has been well recognized that clouds tremendously affect the surface solar irradiance and its direct and diffuse partitions, accurately forecasting solar radiation in cloudy conditions remains a major challenge. This study focuses on two aspects of the challenge: impacts of cloud microphysics and model domain size. First, we will examine the sensitivity of surface solar radiation and its partitions to cloud microphysics by using the state of art Weather Research and Forecasting model specifically designed for simulating and forecasting solar radiation (WRF-Solar). A number of microphysical schemes will be tested, and comparison against the measurements of shallow cumulus clouds and stratiform clouds selected at the DOE ARM SGP Site. Efforts will be made to quantify the resultant uncertainty spread. Second, identifying the physical causes of the underlying model differences is even more challenging. To address this, we will introduce a new model evaluation framework based on different setups of WRF-Solar (single column, LES, and nested WRF). In particular, we will examine the effect of the number of LES grid columns and its lower limit producing reasonable results. Commonly used evaluation metrics will be used in our model evaluation, including the used RMSE, MAE, MAPE, and relative Euclidean distance. The results will provide physical insight into the understanding of cloud-radiation interactions and forecasting of solar radiation in cloudy conditions.

X-ray amorphous material that is variably Mg/Fe/Si-rich and Al-poor and that likely contains secondary alteration products is prevalent in Gale crater sediments and rocks (15-73 wt.%). However, the structure and origin of these materials and their implications for past environmental conditions remain unknown. In this study, we use transmission electron microscopy and synchrotron microprobe analyses to examine Mg/Fe/Si-rich and Al-poor ultramafic soils from the warm Mediterranean climate Klamath Mountains of California and cold subarctic climate Tablelands of Newfoundland, Canada to help interpret environmental conditions during the formation of chemically similar X-ray amorphous material in Gale crater, Mars. Primary glass is absent from the Klamath Mountains and Tablelands materials; secondary X-ray amorphous material includes globular amorphous silica and chemically heterogeneous nanospherical amorphous material and nanocrystalline phases. Globular amorphous silica is only present in soils that undergo extensive periods of cyclic freezing. Fe-containing X-ray amorphous material from the subarctic Tablelands is significantly richer in Mg and Si than X-ray amorphous material from the warmer Klamath Mountains. Fe-rich nanocrystallites contain more Mg and Si in the subarctic Tablelands but are more highly Fe-enriched in the warmer Klamath Mountains. Potential secondary nanocrystalline phyllosilicates are only observed in the warmest examined soil in the Klamath Mountains. These characteristics – the presence or absence of amorphous silica, the chemical composition of X-ray amorphous material, the abundance and composition of Fe-rich nanocrystallites, and the presence or absence of secondary phyllosilicates - provide helpful identifiers to interpret past environmental conditions during the formation of X-ray amorphous material on Mars.