Understanding time-changing tidal characteristics is essential for numerous practical purposes, such as flood prevention, navigation, and ocean engineering. Previous studies mainly focus on tidal evolution in coastal areas while tidal changes in deep water areas receive limited attention due to the lack of long-term high-frequency sea level records. In this paper, we extract the inter-annual and decadal tidal variability in the South China Sea (SCS) from 24 coastal tide gauges and 25-year satellite altimeter observations using the novel S_TIDE toolbox. Through numerous sensitivity experiments, it is found that ~17 independent points (IPs) are suitable for extracting inter-annual and decadal tidal variability in the deep basin of the SCS. It is also found that tidal variability and sea level variability are closely correlated in most parts of the SCS. The high correlation between tidal variability and sea level variability in the central deep basin of the SCS is associated with the El Niño–Southern Oscillation(ENSO). The results obtained from satellite data are less stable and accurate than those obtained from long-term tidal gauge observations, but the methods described here provide a strong foundation for future research on time-varying tidal dynamics using the combination of tide gauges and satellite altimeter data.

The C isotopic composition in macroalgae (δ13C) is highly variable and its prediction is very complex relative to terrestrial plants. To contribute to the knowledge on the variations and determinants of δ13C-macroalgal, we analyzed a large stock of specimens varying in taxa and morphology and inhabiting shallow marine habitats from the Gulf of California Ecoregion featured by distinctive environmental conditions. A large δ13C variability (-34.61‰ to -2.19‰) was observed, mostly explained on the life form (taxonomy, morphology and structural organization), and modulated by the interaction between habitat features and environmental conditions. The intertidal zone specimens had less negative d13C values than in subtidal zone. Except pH, environmental conditions of the seawater do not contribute to the δ13C variability. Specimens of the same taxa showed δ13C similar patterns, to increase or decrease, with latitude (21º-30°N). d13C-macroalgal provides information on the inorganic carbon source used for photosynthesis (CO2 diffusive entry vs HCO3- active uptake). Most species showed a δ13C belong into a range that indicates a mix of CO2 and HCO3- uptake; the HCO3- uptake by active transport is widespread among GCE macroalgae. About 20-34% species depending on cutoff limits for CCM presence showed at least one specimen with δ13C>-10‰, suggesting that potentially could have highly efficient CCM. Ochrophyta presented a high number of species with d13C>-10‰, suggesting widespread HCO3- use by non-diffusive mechanisms. Few species belonging to Rhodophyta relied on CO2 diffusive entry (d13C<-30‰) exclusively. δ13C provides useful information about the physiological and environmental status of macroalgae.

SKB and several other waste management organizations have established the international SKB Task Force on Modelling of Groundwater Flow and Transport of Solutes (TF GWFTS) to support and interpret field experiments. An important objective of the task force is to develop, test and improve tools for conceptual understanding and simulating groundwater flow and transport of solutes in fractured rocks. Work is organized in collaborative modelling tasks. Task 9 focuses on realistic modelling of coupled matrix diffusion and sorption in heterogeneous crystalline rock matrix at depth. This is done by inverse and predictive modelling of different in-situ transport experiments. The ultimate aim is to develop models that in a more realistic way represent retention in fractured rock. Posiva’s REPRO (rock matrix REtention PROperties) experimental campaign has been performed at the ONKALO rock characterization facility in Finland. The two REPRO experiments considered were the Water Phase Diffusion Experiment, addressing matrix diffusion in gneiss around a single borehole interval (modelled in Task 9A), and the Through Diffusion Experiment, which is performed between sections of three boreholes and addressed by modelling in Task 9C. The Long-Term Diffusion and Sorption Experiment (LTDE-SD) was an in-situ radionuclide tracer test performed at the Äspö Hard Rock Laboratory at a depth of about 410 m below sea level. The experimental results indicated a possible deeper penetration of tracers into the rock matrix than expected and the shape of the penetration profiles were not according to theory. This experiment was modelled and interpreted in Task 9B. Task 9D is addressing the possible benefits of the detailed modelling of the experiments in safety assessment calculations. The task is performed by upscaling of Task 9A to conditions applicable for performance assessments of nuclear waste repositories. Of additional interest is the collective work performed by the task force to conceptually understand and interpret the field experiments, and at the same time increase the realism in solute transport modelling. This study would not have been possible without the support from the waste management organizations and the work by the multiple modelling teams.

The efficiency of heat transfer in the outer shell of icy satellites is important to determine the evolution and thermal state of their interior with major implications for the cooling behavior of an internal ocean. In this study, we systematically investigate thermal convection in the ice shell of Europa using an Arrhenius viscosity and accounting for ice I material that is dependent on both grain size and strain rate. To this end, we employ the geodynamical code GAIA [1] with a mixed rheology approach similar to [2], and perform calculations in a 2D Cartesian box and spherical annulus geometry for two values of the ice shell thickness (i.e., 30 and 70 km). In our simulations, we test various constant grain size values. In a first serie of simulations, we tested the importance of the dislocation creep mechanism for modeling convection in Europa’s ice shell. Our results show that, in a mixed diffusion-dislocation creep rheology, diffusion creep is the dominant heat transfer mechanism, similar to the study of [3]. A pure dislocation creep rheology leads to a conductive ice shell. Dislocation creep may become dominant if its rheological prefactor increases by about 5 orders of magnitude, which even taking into account the uncertainty associated with rheological measurements is considered unrealistic. Additional simulations that use a mixed diffusion-basal slip rheology show that for ice shells, basal slip may be a relevant deformation mechanism in addition to diffusion creep. Another important aspect is that the efficiency of heat transfer is larger for a thick ice shell (70 km, compared to a thinner one (i.e., 30 km)). However, the dimensional surface heat flow obtained for a thin ice shell is larger than for a thicker one. This is caused by the rescaling of non-dimensional parameters to a dimensional heat flow. References: [1] Hüttig et al., PEPI 2013; [2] Schulz et al., GJI 2019; [3] Harel et al., Icarus 2020.

We present results that unequivocally demonstrate that glacier moraines erode at their crests and accumulate sediment at their toes, resulting in significant landscape evolution over the lifespan of these landforms. We measured the concentration of cosmogenic 10Be in quartz from ~meter deep soil profiles dug at the crest, flank, and toe of two lateral moraines of different ages in the Mono Basin, CA. The concentrations of 10Be in the profiles show erosion at the moraine crests, and accumulation at their flanks and toes on the order of 0.01 – 0.1 mm/yr for the past 10-20,000 years. Additionally, 10Be concentrations increase downslope significantly. These results are consistent only with sediment transport models that begin with steep and sharp crested moraines that widen and flatten from meters to tens of meters over their lifespans.

The effect of stratospheric ozone depletion is simulated in GFDL AM4 model with three ozone schemes: prescribing monthly zonal mean ozone concentration, full interactive stratospheric chemistry, and a simplified linear ozone chemistry scheme but with full dynamical interactions. While similar amounts of ozone loss are simulated by the three schemes, the two interactive ozone schemes produce significantly stronger stratospheric cooling than the prescribed one. We find that this temperature difference is driven by the dynamical responses to ozone depletion. In particular, the existence of ozone hole leads to strong ozone eddies that are in-phase with the temperature eddies. The coherence between ozone and temperature anomalies leads to a weaker radiative damping as ozone absorbs shortwave radiation that compensates for the longwave cooling. As a result, less wave dissipates at the lower stratosphere, leading to a weaker descending and dynamical heating over the polar lower stratosphere, and hence a stronger net cooling there. The covariance between ozone and temperature is largely suppressed when ozone is prescribed as monthly zonal mean time series, as is the reduction in the radiative damping following ozone depletion. With much lower computational cost, the simplified ozone scheme is capable of producing similar magnitude of ozone loss and the consequent dynamical responses to those simulated by the full chemistry.

Remotely-sensed Solar Induced chlorophyll Fluorescence (SIF) is a novel promising tool to retrieve information on plants’ physiological status due to its direct link with the photosynthetic process. At the same time, narrow band Vegetation Indices (VIs) such as the MERIS Terrestrial chlorophyll index (MTCI), and the Photochemical Reflectance Index (PRI), as well as broad band VIs like the Normalized Difference Vegetation Index (NDVI), have been widely used for crop stress assessment. A match between these remote sensing products and the spatial distribution of soil units is expected; nevertheless, an in-depth analysis of such relationship has been rarely performed so that additional studies are required. In this contribution, we aimed at the comparison in the use of normalized SIF (SIF = SIF/PAR; computed with the Spectral Fitting Method, SFM) and VIs (MTCI, PRI and NDVI) for heat stress assessment in corn, sugar beet and potato at the beginning and towards the end of a heatwave occurring in Selhausen, Germany, 2018. Data were acquired with the HyPlant airborne sensor, which is a high performance imaging spectrometer with around 0.30 nm of spectral resolution in the Oxygen absorption bands. We compared different plots located in the upper (poorer soil characteristics for agriculture such as water holding capacity and content of coarse sediments) or lower landscape terraces; we also evaluated the different remote sensing products in comparison with site specific geophysics-based soil maps. At the beginning of the heat wave we found that, compared with VIs, SIF data showed a clearer differentiation of the stress conditions at a terrace level in potato and sugar beet. However, towards the end of the wave a significant decrease of MTCI and NDVI contrasted with higher SIF in sugar beet and corn. Nonetheless, those crops (sugar beet and corn) did not show significant SIF differences between terraces. A significant spatial match was found between SIF and geophysics-derived soil spatial patterns (p = 0.004-0.030) in fields where NDVI was more homogeneous (p = 0.028-0.499, respectively). This suggests the higher sensitivity of SIF to monitor heat stress compared with common VIs.

Fundamental understanding of the climate responses to solar variability is obscured by the large and complex climate variability. This long-standing issue is addressed here by examining climate responses under an extreme quiet sun (EQS) scenario, obtained by making the sun void of all magnetic fields. It is used to drive a coupled climate model with whole atmosphere and ocean components. The simulations reveal robust responses, and elucidate aspects of the responses to changes of troposphere/surface forcing and stratospheric forcing that are similar and those that are different. Planetary waves (PWs) play a key role in both regional climate and the mean circulation changes. Intermediate scale stationary waves and regional climate respond to solar forcing changes in the troposphere and stratosphere in a similar way, due to similar subtropical wind changes in the upper troposphere. The patterns of these changes are similar to those found in a warming climate, but with opposite signs. Responses of the largest scale PW during NH and SH winters differ, leading to hemispheric differences in the interplay between dynamical and radiative processes. The analysis exposes remarkable general similarities between climate responses in EQS simulations and those under nominal solar minimum conditions, even though the latter may not always appear to be statistically significant.

In the era of overwhelming amounts of data and information being readily available over the web and other media sources it is vitally important to adopt machine-to-machine readable techniques that enable quick, reliable and repeatable resource discovery and then based on rules and definitions, facilitate determination as to whether the data and information are relevant and fit for purpose. Quality metadata can provide such a tool as: • It allows the creation of multiple discipline specific metadata profiles based on international generic standards (e.g. ISO 19115-1, DCAT2) thus improving data management and interoperability of data • When expressed as an XML, Turtle or RDFXML it provides a machine readable format which is easy to manipulate and automate • Through cross-walks to other community defined standards, it can be easily translated and used by multiple communities, (e.g. from the ISO 19115-1 to DCAT2 and schema.org) • It enables the user to understand the data, its purpose, suitability and usability by capturing the history of acquisition and subsequent transformations, the description and evaluations of data quality, and the data dictionaries used • Through the application of consistent vocabulary tags and persistent identifiers it helps improve data discoverability on the web and also trace its usage and incorporation in derivative products • It records and explains how to access and use data by related services, APIs and other tools Australian and New Zealand Metadata Working Group (ANZ MDWG) has been working on development a consistent methods of implementing such tool across disciplines, communities and sectors to facilitate a conversation, support a wider understanding and consistent application. Numerous communication and educational materials have been developed to support it. The current focus of the group is on development of improving interoperability and consistency of data management and description through developing discipline specific profiles and ontologies. This presentation will examine challengers, achievements and current plans of the ANZ MDWG.

Earthquakes happen with frictional sliding, by releasing excess stresses accumulated in the pre-stressed surrounding medium. The geological third body (i.e. fault gouge), originating from the wear of previous slips, contribute to friction stability and plays a key role in the energy released. An important part of slip mechanisms are influenced by gouge characteristics and environment. The study of several types of gouge, as mixtures of different initial porosity and cohesive contact law, allows to link fault gouge properties to its rheological behavior. In this paper, a cohesive fault gouge segment is modeled in 2D with DEM. The analyses of friction coefficient evolution, gouge kinematics and force chains within the gouge highlight the main mechanisms acting on fracture processes. A link is made between the initial state of the gouge and the ductile or brittle character of the whole granular flow. For the investigated data range, three regimes are highlighted: a mildly cohesive regime (ductile behavior), a cohesive regime with agglomerates formation and Riedel shear bands and an ultra-cohesive regime with several Riedel bands followed by ultra-localization (brittle behavior). As a result of this study, the total macroscopic friction generated during the shearing is proposed to be a combination of three contributions: Coulomb friction, dilation and decohesion process. A simplified model is built up to represent these contributions and to be implemented in dynamic rupture modelling at higher scale. The Breakdown energy appears to be controlled by the intensity of these three mechanisms and their associated slip distance.

Interseismic deformation describes the gradual accumulation of crustal strain within the tectonic plate and along the plate boundaries before the sudden release as earthquakes. In this study, we use five years of high spatial and temporal geodetic measurements, including Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) to monitor 3-dimension interseismic crustal deformation and horizontal strain rate in Taiwan. We find significant deformation (strain rate > 8x10-6 yr-1) along the plate boundary between the Philippine Sea Plate and the Eurasian plates in east Taiwan. The high strain rate in the southern part of the Western Foothills is distributed along a few major fault systems, which reveals the geometry of the deformation front in west Taiwan. Our results help identify active faults in southwest and north Taiwan that were not identified before. These findings can be insightful in informing future seismic hazard models.

The western U.S. has millions of acres of forestlands at risk of large and uncharacteristically severe wildfire. This is due to a variety of factors, including decades of fire suppression as well as climate change. Fuel treatments such as mechanical thinnings, prescribed burns, and combinations of thinning and burning in fire-adapted forests can reduce wildfire severity and potentially stabilize sequestered forest carbon in coniferous, fire adapted forests of the western US; resulting in avoided wildfire emissions (AWE) of greenhouse gases (GHG). Accounting for GHG emission benefits of fuel treatments is challenging; hence, scientific consensus and broad stakeholder buy-in from public agencies, non-governmental organizations, and the private sector is key. Using most recent forest vegetation and weather datasets as well as forest growth and wildfire behavior models, we present an avoided wildfire GHG emission accounting framework developed in collaboration with key stakeholders in the western US as well as recent case studies. This probability-based GHG emission accounting framework can not only provide tools to quantify GHG benefits of fuel treatments, but can specifically be employed to help fund fuel treatments through carbon offset credits. The probability-based nature of this GHG emission accounting approach has further application value for risk accounting to forest carbon stocks from other stochastic events (e.g. drought, insect outbreaks) as well as forest-based carbon offset protocols in general.

We examined the Cyclone Global Navigation Satellite System (CYGNSS) retrievals of surface winds and enthalpy fluxes in African easterly waves that led to the formation of 31 Atlantic tropical cyclones from 2018–2021. Lag composites show a cyclonic proto-vortex as early as 3 days prior to tropical cyclogenesis. The distribution of enthalpy fluxes within the proto-vortex does not vary substantially prior to cyclogenesis, but subsequently, there is an increase in the upper extreme values. A negative radial gradient of enthalpy fluxes becomes apparent as early as 2 days before cyclogenesis. These results—based on a novel data blending satellite retrievals and global reanalysis—are consistent with recent studies that have found that tropical cyclone spin-up is associated with a shift of peak convection towards the vortex-core and a radially inward increase of enthalpy fluxes. They provide additional evidence for the importance of surface enthalpy fluxes and their radial structure for tropical cyclogenesis.

Although most tsunamis are generated by the sea-bottom deformation caused by earthquakes, some tsunamis are excited by sea-surface pressure changes. This study theoretically investigated tsunamis generated by sea-surface pressure changes and derived the solutions in 3-D space, whereas most past studies employed 2-D equations. Using the solutions, we simulated and visualized the tsunami generation by a growing pressure change. Negative pressure change made the sea surface uplifted inside the source region and negative leading waves were radiated from the source region. We also simulated the tsunami generation when the pressure change at the sea surface moves with almost the same speed as the tsunami propagation velocity. The tsunami height increased with increasing the travel distance including the dispersion effects. The 3-D solutions in this study, including the vertical velocity distribution, indicate that both the tsunami height and the sea-surface pressure changes contribute to the ocean-bottom pressure changes, suggesting the difficulty in measuring the tsunami height with ocean-bottom pressure observations. When the pressure change source was characterized by short-wavelength components, the dispersion increased tsunami height more extensively than the non-dispersive tsunamis. The 3-D solutions are necessary for describing the tsunami generation where the long-wave approximations are not applicable in open oceans.

A regional meteorology–chemistry model was used to assess the effects of passenger car conversion to battery electric vehicles (BEV) on summer O3 concentrations in Kanto (Japan’s most populous region). Four sensitivity experiments were conducted on different on-road and upstream (power plant and gas station) emission conditions. Daytime 8-h maximum O3 decreased by 3 ppb (5%) and 4 ppb (5%) in urban and inland suburbs, respectively. O3 levels decreased even in urban (VOC-limited regions) because exhaust and evaporative VOC emissions from vehicle and gas stations were reduced effectively (especially alkenes from gasoline evaporation; highly reactive in O3 formation). In the suburbs (NOx-limited regions), reduction of exhaust NOx by BEV shifting was significant, but in urban, even only evaporation measures induced almost the same O3 reduction effect as BEV shifting. The additional emissions from thermal power plants due to BEV night charging contributed little to the next day’s daytime O3 on a monthly average basis. However, on some days, pollutants were stored in the upper part of the stable nighttime boundary layer and could affect the surface O3 as the next day’s mixed layer development. Depending on the O3 sensitivity regime (NOx- or VOC-limited), additional NOx plumes from rural (urban) power plants tended to increase (decrease) the next day’s O3. However, the distribution of the regime changes temporally and spatially. The H2O2/HNO3 ratio was discovered to be a clear indicator for distinguishing regime boundaries and was effective in predicting positive or negative O3 sensitivity to the additional emissions from power plants.

The 15 Jan 2022 Hunga Tonga-Hunga Ha’apai volcano eruption drove global atmospheric waves that propagated into space and impacted the ionosphere. Here we show immediate large-scale electrodynamic effects of the eruption using observations from NASA’s Ionospheric Connection Explorer. We report extreme zonal and vertical ExB ion drifts thousands of kilometers away from Tonga within an hour of the eruption, before the arrival of any atmospheric wave. The measured drifts were magnetically connected to the ionospheric E-region just 400 km from Tonga, suggesting that the expanding wavefront created strong electric potentials which were transmitted along Earth’s magnetic field. A simple theoretical model suggests that the observed drifts are consistent with an expanding wave with a large (>200 m/s) neutral wind amplitude. These observations are the first direct detection in space of the immediate electrodynamic effects of a volcanic eruption and will help constrain future models of impulsive lower atmospheric events.

To better understand the impacts of climate change on Europe, it is important to understand changes in the wintertime large-scale circulation. The framework of weather regimes provides a powerful tool for studying the highly nonlinear Euro-Atlantic circulation, but exactly how these regimes will be altered by anthropogenic climate change is still imperfectly understood. Using the recently developed approach of geopotential-jet regimes, applied to an ensemble of state-of-the-art CMIP6 models, we show that the centres of action of anticyclonic regimes are not projected to change substantially by the end of century, even under an extreme warming scenario. Instead, the regimes are expected to become less persistent, making long-lived blocking events less likely. We show that these two key elements of the regime response can be captured in a simple Lorenz-like model subjected to parameter variations, emphasising the conceptual link between observed atmospheric regimes and the regimes identified in basic mathematical systems.

We investigate the onset of magnetic reconnection, utilizing a fully kinetic Particle-In-Cell (PIC) simulation. Characteristic features of the electron phase-space distributions immediately before reconnection onset are identified. These include signatures of pressure non-gyrotropy in the velocity distributions, and lemon shaped distributions in the in-plane velocity directions. Further, we explain how these features form through particle energization by the out-of-plane electric field. Identification of these features in the distributions can aid in analysis of data where clear signatures of ongoing reconnection are not yet present.