The future increase of methane concentration leads to a raise in water vapor abundance in the middle atmosphere. This will enhance the brightness of noctilucent clouds (NLC). We use an atmospheric background model and a microphysical model to study the associated absorption of solar radiation in the period 1950 to 2100. At 69°N mean absorptions at λ=126nm will increase from ~3% to ~7% from 1950 to 2100, respectively. Locally, the absorption can increase to ~30% in the year 2100. In the visible we find an increase from 0.0030% (1950) to 0,020% (2100), i.e., by a factor of ~7, and local maxima up to 0.35% in 2100. The results are similar for polar latitudes (79°N) but are smaller at middle latitudes (58°N). Future mean absorptions are comparable to solar cycle variations, but much larger locally. The ice mass bound in NLC increases from 677 to 1871 tons in 1950 and 2100.

Offshore northern Ishigaki-Jima Island, in the southern Okinawa Trough, offers outstanding opportunities to explore the rifting stage of a backarc system. We report the results of integrated marine geological and geophysical surveys with high-density survey lines in this area. We identify a graben bounded by normal faults and extending approximately 59 km in an ENE-WSW direction off-axis of the southern Okinawa Trough. Submarine volcanoes with active hydrothermalism and associated intrusive structures lie in the graben. Magnetic anomaly and seismicity data in and around the graben suggest the presence of relatively shallow magma acting as a heat source. All features identified in and around the graben suggest active rifting in the southern Okinawa Trough.

Long-term post-seismic gravity change (PGC) of the 2004 Sumatra-Andaman earthquake (Mw9.1-9.3) detected by GRACE + GRACE-FO is modeled sufficiently by an exponential function until the 2012 Indian-Ocean earthquake (Mw8.8) but gravity increasing became constant after that. An interpretation is PGC of the 2004 earthquake was almost completed in 2012 and that of the 2012 earthquake proceeded constantly. Assuming this, I calculate their spatial distributions. PGC of the 2012 earthquake was expanded along the faults of the 2004 earthquake and the peaks of PCGs of the two earthquakes appeared at a same location. This suggests another interpretation, namely, PGC of the 2004 earthquake has another long-term component expected by Burgers rheology and PGC of the 2012 earthquake is slight. Spatial distributions of PGC on this assumption support this interpretation. This is the first result showing Burgers rheology is appropriate to consider the viscosity of upper mantle based only on satellite gravimetry.

Hydrothermal alteration of ultramafic rock (serpentinization) creates extremely reducing (H2-rich) fluids in the oceanic crust, resulting in strong thermodynamic drives to reduce CO2 to organic molecules in the absence of life. Timescales on which such hydrothermal fluids circulate (thus produce or destroy such organic molecules) have remained enigmatic. In their new publication, Moore et al. (2021, https://doi.org/10.1029/2021JC017886) present compelling radioisotope-based estimates of fluid residence times in a widely known site of purported abiotic synthesis - the Lost City Hydrothermal Field. Using a model that accounts for the sorptive behavior of Ra radionuclides during circulation, they find that fluids at Lost City must have inordinately short residence times, averaging 0.5 to 2 yr or less. The study represents a critical step forward in our understanding of Earth’s abiotic organic kitchen, as it now places a constraint on the timeframe in which such organic molecule creation should occur in such fluids (if at all) prior to venting at the seafloor.

This study investigates the direct radiative-convective processes that drive and maintain aggregation within convection permitting elongated channel (and smaller square) simulations of the UK Met Office Unified Model (UM). Our simulations are configured using three fixed sea surface temperatures (SSTs) following the radiative-convective equilibrium model intercomparison project (RCEMIP) protocol. By defining cloud types based on the vertical distribution of condensed water, we study the importance of radiative interactions with each cloud type to aggregation. We eliminate the dependence of the vertically-integrated frozen moist static energy (FMSE) variance budget framework on SST by normalizing FMSE between theoretical upper and lower limits based on SST. The elongated channel simulations reach similar degrees of aggregation across SSTs, despite the contributions of normalized shortwave and longwave interactions decreasing with SST. High-cloud longwave interactions are the main drivers and maintainers of aggregation. Their influence decreases with SST as high clouds become less abundant. This SST-dependence is consistent with changes in grid spacing and RHcrit, however the magnitude of high-cloud longwave interactions is likely reduced as grid spacing and RHcrit are reduced. Both factors tend to decrease condensed water path and cloud top height, decreasing the anomalous longwave heating rates of these clouds. Shortwave interactions with water vapor are key maintainers of aggregation and are dependent on SST and the degree of aggregation itself. The analysis method used provides a new framework to compare the effects of radiative-convective processes on self-aggregation across different SSTs and model configurations in order to improve our understanding of self-aggregation.

According to the different orientations of the interplanetary magnetic field (IMF), the planetary shock can be either quasi-parallel or quasi-perpendicular. Under quasi-parallel conditions a significant number of solar wind suprathermal particles are reflected from the shock and drift along IMF, forming an extended and highly turbulent region called the foreshock where various nonlinear plasma phenomena are observed. In this research, we perform a case study of the structures in the foreshock region at Mars observed by Mars Atmosphere and Volatile Evolution (MAVEN). We use data from plasma analyzer STATIC and magnetometer MAG to analyze ion beams angular spectrum and magnetic field dynamics. We show that the observed structures are consistent with Short Large-Amplitude Magnetic Structures (SLAMS), commonly detected in foreshock regions of magnetized and unmagnetized bodies throughout the Solar system. Finally, we calculate the magnetic Mach number to analyze the characteristics of the observed foreshock structures. The analysis shows, that SLAMS are formed by the resonance between plasma waves propagating along the IMF and the backstreaming scattered solar wind H+ and exospheric O+ and O2+ ions, with the dominant impact of O2+ ions.

We investigate ionospheric disturbances using the total electron content (TEC) data retrieved by the three satellites after the foreshock of the 2011 Tohoku Earthquake on 9 March 2011. Co-seismic ionospheric disturbances (CIDs) appeared to extend from an onset point concentrically in all of the satellite data. We have found, however, that the geographic coordinates of the onset points did not coincide if the observed CIDs were assumed to occur at one altitude. Admitting that the altitudes of the onset points are different, we searched for coinciding geographic coordinates of the onset points using the two data sets by changing the altitudes and identified the altitude of the two onset points at 155.4 and 234.9 km, and the onset time at these altitudes. As a result, the vertical velocity of acoustic wave is estimated to be 1.04 km/s from the travel time between the altitudes of 155.4 and 234.9 km. This is 1.4 times higher than the sound velocity calculated using the empirical model NRLMSISE-00. The present study provides a method of determining the source location of the acoustic wave from the ionospheric TEC analysis without using the seismic data.

For high-resolution regional geodetic applications, the International Terrestrial Reference Frame (ITRF) is complemented by regional densifications. These are realised either as multi-year solutions related to a tectonic plate (e.g., EUREF for Europe) or as epoch reference frames (ERFs) to capture non-linear geophysical effects like earthquakes or loading displacements (e.g., SIRGAS for Latin America). These GNSS-only-based regional frames have in common that their geodetic datum is aligned with the ITRF datum at a specific epoch. Their origin is thus geocentric only in a mean sense and does not always coincide with the instantaneous centre of mass. Here, we present studies on a direct geocentric realisation of regional ERFs. We propose to realise the geodetic datum for each epoch by combining global GNSS, SLR and VLBI networks via measured local ties at co-located sites. An equally-distributed global GNSS network is used to realise the orientation via a no-net-rotation constraint and is densified by the stations of the regional subnetwork. The developed combination and filtering strategy aims to guarantee a stable datum realisation for each epoch-wise solution. The effectiveness of our methods is validated against the current operational realisation of the SIRGAS Latin American reference frame. Comparing with geophysical loading models relating to the Earth’s centres of mass and figure, we show that the realised geocentric displacement time series directly reflect seasonal geophysical processes. Moreover, as the approach does not need to rely on co-location sites in the region of interest, it is conceptually transferrable to other global regions.

A new approach to monitoring stochastic features of earthquake series was applied to track the preparatory process of the 2017 Tehuantepec, Mexico, Mw8.4 earthquake. The seismicity was parameterized by elapsed times and epicentral distances from the directly preceding earthquakes and by earthquake magnitudes. The transformation to equivalent dimensions ensured the comparability of these parameters. We were calculating the average distance between earthquakes in the transformed parameter space in moving in time data windows, each consisting of 100 events. The average distance exhibited a consistent upward trend from ten to two years before the main shock. Then, it declined until the main shock. This precursory up-down signal was highly significant statistically. We showed that the detected time changes of the average distance resulted from the evolution of the earthquake clustering in the considered parameters' equivalent dimensions space.

CO2 geological storage is a promising method to dispose excess CO2 in the atmosphere, and the existence of brine in deep saline aquifer and below oil reservoir may lead to salt precipitation in pore space for dry-out formation. Water diffusion coefficient is helpful to evaluate salt precipitation. However, limited previous data cant satisfy the need of CO2 geological storage. Raman quantitative spectroscopy is used to observe water diffusion in CO2 in a high-pressure capillary cell and corresponding diffusion coefficients are obtained at 10-50 MPa and 353.15-433.15 K. Diffusion coefficient is temperature and pressure dependent, and also increases linearly with the reciprocal of CO2 density. Free volume theory and PC-SAFT EOS are utilized to establish a thermodynamic model for water diffusion in CO2, and it predicts diffusion coefficient accurately at 10-50 MPa and 353.15-433.15 K. Besides, diffusion coefficient is used to evaluate when salt precipitation occurs and salt precipitation process is observed in a one-dimensional capillary tube and a two-dimensional micromodel respectively.

The evolution of mesoscale eddies is crucial for understanding the ocean energy cascade. Using global reanalysis sea surface velocity data and mesoscale eddy trajectory product tracked by satellite altimeters, this study aims to reveal the coherence of eddy kinetic energy (EKE) variation to the low-frequency ageostrophic energy during the eddy life span. The variation of EKE through the eddy life is highly coherent to that of the 7d low-passed ageostrophic kinetic energy with a correlation coefficient of -0.95. The low-frequency ageostrophic motions supply 43% of the EKE variation at the growing stage of mesoscale eddies, and absorb 45% at the decaying stage, comparing to 7% and 9% of contributions for submesoscale motions. The evolution rate of the EKE during the eddy life span is consistent with the barotropic conversion rate of the low-frequency motions, further confirming the dominant role of the low-frequency motions in the eddy growing and decaying.

The ‘super-station’ approach has been adopted since 1980s as a pragmatic method of improving extreme‑value predictions by grouping short-length datasets from several measurement stations to become a larger dataset to reduce uncertainties due to random sampling variation.  El Rafei et al. (2023, https://doi.org/10.1029/2023GL105286) analyzed reanalysis, and randomly generated, wind extremes datasets and suggested that this technique can introduce unexpected biases in typical situations.  We complement their work and demonstrate by Monte-Carlo simulation, assuming the same number of grouped stations and data lengths used, that applying the grouping technique to samples of properly de-trended datasets to meet the homogeneity assumption does not lead to biased prediction of extremes.  In addition, the grouping technique effectively reduces the uncertainty and sampling errors that result from short-length datasets from individual stations of consistent meteorology .

The Izu-Bonin-Mariana (IBM) subduction system is a key natural laboratory providing fundamental insights into subduction dynamics and the evolution of associated upper plate magmatism. To investigate the processes associated with subduction initiation and the subsequent evolution of the Philippine Sea plate, International Ocean Discovery Program (IODP) Expedition 351 recovered a complete sedimentary sequence and the top of the underlying volcanic basement at Site U1438 located in a rear-arc position. This offers a unique opportunity to study for the first time and in extreme detail the styles, products, and timing of the volcanic events that marked the emplacement, growth, and demise of the Kyushu-Palau volcanic arc within the IBM system. Here we report a magnetostratigraphy for Site U1438 based on ~60,000 remanence directions isolated from 1063 archive half-core sections and 429 discrete specimens. This identified 112 well-constrained magnetic reversals that may be correlated with the geomagnetic polarity timescale. When combined with additional biostratigraphic and geochronological constraints, this allows construction of a high-resolution age model for Site U1438 and the determination of changes in sedimentation rates during the evolution of the Kyushu-Palau arc. These age constraints show that following subduction initiation at ~52 Ma, diffuse volcanism in both the forearc and rear-arc preceded the initial emplacement of the Kyushu-Palau arc at 44.2 Ma, which then grew through four compositionally distinct eruptive phases until 29.2 Ma. Rollback of the Pacific slab then triggered rifting of the arc (29.2-24.3 Ma), leading to back-arc spreading in the Shikoku and Parece-Vela basins.

This paper presents the local correlation method of low-SNR (Signal to Noise Ratio) and strongly RFI (Radio Frequency Interference) contaminated DOR (differential one-way ranging) signals with China’s lunar spacecraft. Unlike the Very Long Baseline Interferometry (VLBI) FX correlator used in China VLBI net, the core of local correlation is to construct the received signal model based on the intrinsic characteristics of DOR signals, then extract the residual frequency and phase relative to the model. The performance of the method is verified by means of orbit determination and post-fit residuals analysis. The RMS (root-mean-square) of Delta-DOR delay after orbit determination are 3.7 ns and 0.83 ns when tones SNR varied of 1 dBHz ∼ 20 dBHz and 14 dBHz ∼ 26 dBHz in two individual experiments. The computed standard deviation of post-fit delay residuals is compatible at 3 sigma level with the theoretical spacecraft thermal noise. Local correlation provides a solution to the special RFI contaminated DOR signals process. The precision of Delta-DOR delay with strong RFI keeps the same level of that without interference.

A new technique for estimating the global-scale pattern of magnetospheric convection in the ionosphere is presented. The technique uses the SuperDARN line-of-sight velocity observations combined with an empirical convection model and the assumption that the resulting velocity field is divergence free. In contrast to other techniques for convection estimation, it does not express the velocity field in terms of known basis vectors and it does not assume that the velocity can be determined from a static potential. The velocity is estimated by applying Bayesian inverse theory to the input data, model, and constraints. Linear equations for the plasma velocity at every point in the domain are solved simultaneously in a least-squares sense. Application of the technique results in convection patterns with spatial resolution equal to the calculation grid. The resulting patterns conform with expectations based on the observed IMF conditions and display features that show close correspondence to simultaneously observed features in the auroral luminosity.

The recent spacecraft observations by MMS and Van Allen Probes associated with electromagnetic ion cyclotron waves (EMIC) in the Earth magnetosphere emphasize the important role of multi-ion plasma composition for generation and characteristics of these emissions. We show that main properties of the coherent EMIC waves can be explained with the concept of ‘multi-ion oscillitons’ (Sauer et al., 2001). In a plasma with two types of ions of different masses (e.g. protons and oxygen ions), oscillitons arise from the exchange of momentum and energy between the two ion components, with the electromagnetic field acting as a mediator. At frequencies near cross-over frequencies of different wave modes in the multi-ion plasma the nonlinear resonance which strongly amplifies the seed unstable mode can be excited. A small phase difference in oscillations of different ion species leads to a nonlinear wave beating and generation of wave packets. The ‘resonance ‘ frequency is characterized by a local maximum of the phase velocity and the coincidence of phase and group velocity. It is suggested that the oscillitons are triggered by the instability due to the proton temperature anisotropy and may propagate outside the source region. The generation of coherent waves by oscillitons is of general nature and may contribute to understand the manifold of phenomena in other space plasma environments in which the dynamics of minor ion admixtures cannot be neglected. The concept of oscillitons can also be applied to the momentum exchange between particle groups of the same mass, but different temperature.

Eight M≥7.0 earthquakes have occurred around Bayan Har block since 2000, resulting huge casualties and countless economic loss. Specifically, four M≥6.0 earthquakes occurred near the western boundary of Bayan Har block from 2008 to 2020. Stress interactions among them are comprehensively investigated by applying ETAS (epidemic-type aftershock sequence) model and calculating dCFS (Coulomb failure stress change). The viscoelastic dCFS induced by proceeding Yutian earthquakes on hypocenters of 2012, 2014 and 2020 Yutian earthquakes are -1.5004×10-4 , 3.5820×10-3 and 1.4770×10-1 MPa, respectively. The background probabilities of 2008, 2012, 2014 and 2020 Yutian earthquakes are 0.87, 0.97, 1.5×10-3 and 8.7×10-5, respectively. Combining those two kinds of evidence, we conclude that 2008 and 2012 Yutian earthquakes are more like background earthquakes and 2014 and 2020 Yutian earthquakes are triggered by proceeding Yutian earthquakes.

Assessing volcanic hazard in regions of distributed volcanism is challenging because of the uncertain location of future vents. A statistical-mechanical strategy to forecast future vent locations was recently proposed. Here we further develop and test that strategy with analog models. We stress a gelatin block in controlled conditions and observe air-filled crack trajectories. We use the observed surface arrivals to sample the distributions of parameters describing the stress state of the gelatin block, combining deterministic crack trajectory simulations with a Monte Carlo approach. We find the algorithm retrieves the stress imposed on the gelatin and successfully forecasts the arrival points of subsequent cracks in the same experimental setups. We discuss how the approach may be used to gain insight on the stress state of regions of distributed volcanism.