Following the 2011 M9 Tohoku-Oki earthquake, the interplate seismicity drastically increased in the downdip extension; however, it disappeared within the rupture area. An Mw7.0 earthquake occurred in the downdip extension off Miyagi in March 2021, followed by an Mw6.7 earthquake in May 2021. To examine the initial evolution of the next M9 earthquake cycle, we examined the regional seismicity and source processes of the two M~7 earthquakes. We found that the March Mw7.0 earthquake was nucleated at a conditionally stable patch where repeating earthquakes emerged after the Tohoku-Oki earthquake. The earthquake initiation from a conditionally stable patch at the deep plate boundary is probably a transient feature in the postseismic period of the previous M9 earthquake. The stress enhancement caused by the Mw7.0 event facilitated the subsequent May Mw6.7 earthquake. These two M~7 earthquakes ruptured the western seismic patches of the 1978 Mw7.5 Miyagi-Oki earthquake, which is the most recent typical earthquake in an ~40-year interval of M~7.5 earthquake sequence, and loaded the eastern shallow seismic patches for the sequence. Interplate seismicity in the updip area disappeared after the 2011 Tohoku-Oki earthquake. Assuming that the spatial pattern of interplate earthquakes will be restored to a situation similar to that before the Tohoku-Oki earthquake, the seismically active area should gradually expand to the updip area. Continued monitoring of interplate seismicity is essential to examine how plate-locking evolves during the M9 earthquake cycle.

Accelerated loss of the sea-ice cover and increased human activities in the Arctic emphasize the need for skillful prediction of sea-ice conditions at sub-seasonal to seasonal (S2S) time scales. To assess the quality of predictions, dynamical forecast systems can be benchmarked against reference forecasts based on present and past observations of the ice edge. However, the simplest types of reference forecasts –persistence of the present state and climatology– do not exploit the observations optimally and thus lead to an overestimation of forecast skill. For spatial objects such as the ice-edge location, the development of damped-persistence forecasts that combine persistence and climatology in a meaningful way poses a challenge. We have developed a probabilistic reference forecast method that combines the climatologically derived probability of ice presence with initial anomalies of the ice-edge location, both derived from satellite sea-ice concentration data. No other observations, such as sea-surface temperature or sea-ice thickness, are used. We have tested and optimized the method based on minimization of the Spatial Probability Score. The resulting Spatial Damped Anomaly Persistence forecasts clearly outperform both simple persistence and climatology at sub-seasonal timescales. The benchmark is thus about as skilful as the best-performing dynamical forecast system in the S2S database. Despite using only sea-ice concentration observations, the method provides a challenging benchmark to assess the added value of dynamical forecast systems.

Existing tools for sewer network modelling are accurate but too slow for a range of modern applications such as optimisation or uncertainty analysis. Reduced complexity sewer network models have been developed as a response to this, however, current applications are slow to set up and still require high-fidelity models to be run for calibration. In this study, we compare and develop graph partitioning techniques to automatically group sections of sewer network into semi-distributed compartments. These compartments can then be simulated without calibration in the integrated modelling framework, CityWat-SemiDistributed (CWSD), which has been developed for application to sewer network modelling as part of this study. We find that combining graph partitioning with CWSD can produce accurate simulations 100-1,000x more quickly than existing high-fidelity modelling. We compare a range of graph partitioning techniques to enable users to specify the level of spatial aggregation of the partitioned network, also enabling them to preserve key locations for simulation. We test the impact of temporal resolution, finding that accurate simulations can be produced with timesteps up to one hour. Our experiments show a log-log relationship between temporal/spatial resolution and simulation time, which would enable a user to pre-specify the speed and accuracy needed for their application. We expect that the speed and flexibility of the approach presented in this work may facilitate a variety of novel applications of sewer network models ranging from continuous simulations for long-term planning to spatial optimisation of network design.

A document by José de Jesús Salas Pérez. Click on the document to view its contents.

Long-term temperature changes drive coastal Marine Heat Waves (MHW) trends globally. Here, we provide a more comprehensive global analysis of cross-shore gradients of MHW and SST changes using an ensemble of three satellite SST products during recent decades. Our analysis reveals depressed onshore SST trends in more than 2/3 of coastal pixels, including both eastern and western boundary current systems. These were well correlated with depressed trends of MHW exposure and severity, ranging from a -2 to -10 decrease in MHW days per decade and a –2.5 to –15°C.days per decade decrease in cumulative intensity. Results were consistent across all satellite products, indicating that these cross-shore gradients are a robust feature of observations. ERA reanalysis data shows that neither air-sea heat fluxes nor wind driven upwelling were found to be consistent drivers. Global ocean circulation models (OFAM3 and ACCESS-OM2) have limited ability to simulate the depressed onshore trends. A heat budget analysis performed in the Chilean coast region, where models agree with observations, showed that the gradient of temperature change was controlled by an onshore increase of longwave radiative cooling, despite an increase in upwelling. This highlights the complexity of small-scale coastal ocean-atmosphere feedbacks, which coarser resolution climate models do not resolve. Here, we show that global coastal regions may act as thermal refugia for marine ecosystems from aspects of climate change and pulsative (MHW) changes. Contrary to the literature, our results suggest that driving mechanisms are region dependant, stressing the necessity to improve climate models resolution.

In earth science, we must often move and store tremendous amounts of data from remote locations. Present options are typically limited to costly proprietary devices which are rigid in structure and require numerous ongoing expenses. The Openly Published Environmental Sensing (OPEnS) Lab at Oregon State University developed the OPEnS Hub, a new approach using low-power, open-source hardware and software to achieve near real-time data logging from the field to the web. The Hub is two orders of magnitude less expensive than commercial products, inherently modular and flexible, and aims to reduce technical barriers for users with little programming experience. Data can be collected remotely from nearly anywhere on Earth using a host of transmission protocols to relay data from distributed in-situ monitoring devices. Telemetry options include 900 MHz Long Range Radio (LoRa) with up to 25 km range and Nordic Radio Frequency (nRF) for higher data rates. Internet gateways include the established cell network infrastructure, Wi-Fi for high bandwidth applications, and Ethernet where available. The OPEnS Hub is capable of mesh networking with several nodes and backs up to an onboard microSD card. The Hub engages a dynamic, low-latency portal to Google Sheets via the free Application Programming Interface (API), PushingBox, and an adaptable Google Apps Script. This framework was tested on 12 unique sensor suites at remote sites in Oregon. This manuscript details our methods and evaluates PushingBox, Google Apps Script, Adafruit Industries’ open-hardware Feather development boards, the Hypertext Transfer Protocol (HTTP), and the foregoing modes of data transfer.

We model an interval of sustained northward interplanetary magnetic field, for which we have a comprehensive set of observational data. This interval is associated with the arrival of an interplanetary coronal mass ejection. The solar wind densities at the time are particularly high and the interplanetary magnetic field is primarily northward. This results in strong auroral emissions within the polar cap in a cusp spot, which we associate with lobe reconnection at the high-latitude magnetopause. We also observe areas of upwards field-aligned current within the summer Northern Hemisphere polar cap that exhibit large current magnitudes. The model is able to reproduce the spatial distribution of the field-aligned currents well, even under changing conditions in the incoming interplanetary magnetic field. Discrepancies exist between the modeled and observed current magnitudes. Notably, the winter Southern Hemisphere exhibits much lower current magnitudes overall. We also model a sharp transition of the location of magnetopause reconnection. This changes rapidly from a subsolar location at the low-latitude magnetopause under southward interplanetary magnetic field conditions, to a high-latitude lobe reconnection location when the field is northward. This occurs during a fast rotation of the IMF at the shock front of a magnetic cloud.

Although some plasma waves exhibit the largest growth rate and amplitude at 90deg wave normal angle (WNA), particle scattering by these waves in a quasilinear (QL) sense has not been examined previously. Using test-particle calculation and QL theory, the present study investigates the proton scattering by equatorial fast magnetosonic waves (MSWs; a.k.a equatorial noise) with varying WNAs including 90deg. Comparison with the diffusion coefficients in momentum space obtained from the test-particle approach indicates that the QL diffusion coefficients given by, e.g., Kennel and Engelmann (1966) are valid up to 90deg WNA, provided that MSWs described conform to the usual QL theory assumptions. The test-particle dynamics due to MSWs at 90deg WNA are examined in detail. Although in the QL picture, protons are only supposed to resonate with MSWs of integer harmonic frequencies at perpendicular propagation, the presence of slightly off-integer harmonic modes as part of a narrowband discrete spectrum of incoherent MSWs plays an important role in making the proton scattering stochastic. Considering the recent test-particle result of bounce-averaged resonance of energetic protons, non-zero wave power at the WNAs >~ 89.5deg typically excluded in QL diffusion can be important for ring current proton dynamics.

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.

High latitude glacierized coastal catchments of the Gulf of Alaska (GoA) are undergoing rapid hydrologic changes in response to climate change and glacial recession. These catchments deliver important nutrients in the form of both inorganic and organic matter to the nearshore marine environment, yet are relatively understudied with respect to characterization of the solute generation processes and total yields. Using multiple linear regression informed by Bayesian Information Criterion analysis we empirically demonstrate how watershed characteristics affect solute generation as represented by concentration-discharge relationships. We find that watershed mean slope and relief control solute generation and that solute yields are influenced most by glacier coverage. We contribute a new flux and concentration-discharge based conceptualization for understanding solute cycles across a hydroclimatic gradient of GoA watersheds that can be used to better understand future watershed responses to rapid hydrologic change.

Sensitivities of the backscattering properties to microphysical properties (in particular, size and shape) of mineral dust aerosols are examined based on TAMUdust2020, a comprehensive single-scattering property database of irregular aerosol particles. We develop the bulk mineral dust particle models based on size-resolved particle ensembles with randomly distorted shapes and spectrally resolved complex refractive indices, which are constrained with in-situ observations reported in the literature. The lidar ratio is more sensitive to particle shape than particle size, while the depolarization ratio is sensitive to particle size. The simulated bulk backscattering properties (i.e., the lidar ratio and the depolarization ratio) of typical mineral dust particles with effective radii of 0.5–3 µm are reasonably consistent with lidar observations made during several field campaigns. The dust bulk optical property models are applicable to lidar-based remote sensing of dust aerosol properties.

Different precipitation products are assessed for their skill in capturing orographic precipitation over the western United States using two popular methods. The first method defines orographic indices using orographic enhancement and moisture content that represents the amount of moisture advected over sloping terrain. In contrast, the second method classifies precipitation events into orographic and non-orographic events. NCEP Stage-IV product used as a reference. All of the evaluated products show more significant errors for the orographic than the non-orographic events. The Global Precipitation Mission (GPM) Dual-frequency Precipitation Radar (DPR), combined radar and radiometer (COMBINE), Microwave Humidity sounder (MHS), and GPM Microwave Imager (GMI) severely underestimate the precipitation rates, especially for heavy precipitation (> 4 mm/day), whereas infrared precipitation of the Integrated Multi-satellite Retrievals for GPM (IMERG-IR) and a reanalysis product (ERA5) show relatively better estimation. Satellite products tend to show a lower fraction of precipitation occurrence and amount for orographic than no-orographic classes. It was found that rate BIAS varies with seasons, so in cold seasons satellite precipitation products tend to underestimate while in warm-season they (except DPR) tend to overestimate precipitation amount. Most of the satellite products severely underestimate precipitation volume at relatively colder surfaces (< 10 0C) and lower TPW (<15mm), but ERA5 shows little rate BIAS in such cases. The underestimation tends to be larger for orographic than non-orographic events. In contrast, ERA5 shows relatively large underestimation at warmer temperatures (>20 0C), where satellite products tend to overestimate precipitation amounts.

Lightning is observed to incept in thundercloud electric fields below the threshold value $E_k$ for discharge initiation. To explain this, the local enhancement of the electric field by hydrometeors is considered. The conditions for the onset of positive corona discharges are studied in air for ellipsoidal geometries. A hydrometeor is simulated as an individual charged conductor in zero ambient field; there is only a field generated by the charge on the hydrometeor surface. By doing so, the feasibility of corona inception from ellipsoidal hydrometeors can be formulated based on the self-sustaining condition of electron avalanches. For representative hydrometeor volumes and typical thundercloud pressure, values between $1.2\,E_k$ and $37\,E_k$ were found for the onset electric field at the tip of the ellipsoid. From simulations the required ambient electric field for corona onset from an uncharged hydrometeor can then be derived. This results in values between $0.07\,E_k$ and $0.8\,E_k$ for semi-axes aspect ratios between 0.01 and 1. The charge required on the hydrometeor surface for corona onset is minimum for semi-axes aspect ratios between 0.04 and 0.07 depending on the considered hydrometeor volume. For the simulated hydrometeors, the values of this onset charge for typical pressures are between 1500\,pC and 3200\,pC. Including a size-correction for comparison to in situ measurement shows agreement with measured precipitation charges. From the results it is concluded that corona onset from ellipsoidal hydrometeors of a realistic volume can be achieved in thundercloud conditions for certain aspect ratios.

The size distribution of frazil ice is currently unconstrained in ice shelf cavity modeling. Here we observe the time-dependent behavior of the number and size of frazil ice particles in an Ice Shelf Water plume. A novel acoustic scattering inversion was used to infer frazil ice crystal diameters, assuming a log-normal distribution. Observation sites were on land-fast sea ice approximately 13 and 33 km from the front of the McMurdo Ice Shelf, Antarctica. The water column from the ice-water interface to 30 m below mean sea level was monitored over 3 weeks in November of 2016 and 2017. At 15 m below sea level the mean frazil crystal diameter was $\sim$\SI{1}{\milli\metre}. Fractional ice volume, derived from frazil crystal size and number density, correlates with in-situ supercooling (up to \SI{50}{\milli\kelvin} at \SI{15}{\metre} below sea level). The data presented here provide valuable input for model initiation and evaluation.

The transition from the Semail ophiolite mantle to the underlying metamorphic sole was drilled at ICDP OmanDP Hole BT1B. We analyzed the bulk major, volatile and trace element compositions of the mantle-derived listvenite series and metamorphic rocks, with the aim to constrain chemical transfers associated to peridotite carbonation along the ophiolite basal thrust. The listvenite series comprise variously carbonated serpentinites and (fuchsite-bearing) listvenites. They have high CO2 (up to 43.2 wt.%) and variable H2O (0-12.1 wt.%). Yet, they have compositions close to that of the basal banded peridotites for most major and lithophile trace elements, with fuchsite-bearing listvenites overlapping in composition with amphibole-bearing basal lherzolites (e.g., Al2O3= 0.1-2.2 wt.%; Yb= 0.05-1 x CI-chondrite), The protolith of the listvenite series was likely similar in structure and composition to serpentinized banded peridotites which immediately overlie the metamorphic sole elsewhere in Oman. The listvenite series are enriched in fluid mobile elements (FME) compared to Semail peridotites (up to ~103-104 x Primitive Mantle), with concentrations similar to the underthrusted metabasalts and/or metasediments for Cs, Sr and Ca and sometimes even higher for Pb, Li, As, and Sb (e.g., Li up to 130 ppm; As up to 170 ppm). We also observe a decoupling between Sr-Ca enrichments and other FME, indicating interactions with several batches of deep CO2-rich fluids transported along the basal thrust. These results suggest that peridotite carbonation could represent one of the major trap-and-release mechanisms for carbon, water and FME along convergent margins.

Quantifying Effective Radiative Forcing due to aerosol-cloud interactions (ERFACI) remains a largely uncertain process, and the magnitude remains unconstrained in general circulation models. Previous studies focus on the magnitude of ERFACI arising from all cloud types, or examine it in the framework of dynamical regimes. Aerosol forcing due to aerosol-cloud interactions in the HadGEM3-GA7.1 global climate model is decomposed into several global observational cloud regimes. Regimes are allocated to model gridboxes and forcing due to aerosol-cloud interactions is calculated on a regime-by-regime basis with a 20-year meaning period. Patterns of regime occurrence are in good agreement with satellite observations. ERFACI is then further decomposed into three terms, representing radiative changes within a given regime, transitions between different cloud regimes, and nonlinear effects. The total global mean ERFACI is -1.8 Wm-2. When decomposed, simulated ERFACI is greatest in the stratocumulus regime (-0.75 Wm-2).

Recent studies have found that terrestrial dryness indices like the Palmer Drought Severity Index, Standardized Precipitation Evapotranspiration Index, and Aridity Index calculated from climate model projections are mostly negative, implying a drier land surface with future warming. Yet, the same models’ prognostic runoff and bulk soil moisture projections instead feature regional signals of varying sign, suggesting that the dryness indices could overstate climate change’s direct impacts. Observed trends also show this “index-impact gap.” Most studies have attributed this gap to the indices’ omission of CO2-driven stomatal closure. However, here we show that the index-impact gap is still wide even in model experiments that switch off CO2 effects on plants. In these simulations, mean PDSI, Aridity Index, and SPEI still decline broadly with warming, while mean runoff and bulk soil moisture still respond more equivocally. This implies that CO2-plant effects are not the dominant or sole reason for the index-impact gap.

Connectivity provides a framework for analyzing coastal sediment transport pathways, building on conceptual advances in graph theory from other scientific disciplines. Connectivity schematizes sediment pathways as a directed graph (i.e., a set of nodes and links). Existing techniques in graph theory and network analysis provide a low barrier to entry for using connectivity to quantify complex coastal systems, exemplified here using Ameland Inlet in the Netherlands. We divide the study site into geomorphic cells (i.e., nodes), and then quantify sediment transport between these cells (i.e., links) using a numerical model. The system of cells and fluxes between them are then schematized in a network described by an adjacency matrix. Network metrics like link density, asymmetry, and modularity quantify system-wide connectivity. The degree, strength, and centrality of individual nodes identify key locations and pathways through the system. These metrics allow us to address fundamental questions about sediment bypassing of Ameland Inlet and the optimal placement of sand nourishments. Connectivity thus provides a novel and valuable technique for predicting the response of our coasts to climate change and the human adaptations it provokes.