Local Seismic Response (LSR) studies are considerably conditioned by the seismic input features due to the non-linear soil behavior under dynamic loading and the sub-surface site conditions (e.g., mechanical properties of soils and rocks and geological setting) [1][2]. The selection of the most suitable seismic input is a key point in LSR. Unfortunately, a few natural recordings are available at seismic stations in near field areas [3][4]. Then, synthetic accelerograms can be helpful in LSR analysis in urbanized near field territories. Synthetic accelerograms are generated by simulation procedures that consider adequately supported hypotheses about the source mechanism at the seismotectonic region and the wave propagation path towards the surface. Hereafter, mainshocks recorded accelerograms at near field seismic stations during the 2016-17 Central Italy seismic sequence have been compared with synthetic accelerograms calculated by EXSIM code [5] [6]. The outcomes show that synthetic signals can reproduce the high-frequency content of seismic waves at near field areas. Then, in urbanized near field areas, synthetic accelerograms can be fruitfully used in Microzonation studies. References [1] Vessia G. et al. (2013), Bull. Earthq. Eng., 11(5), 1633-1660. [2] Vessia G. et al. (2021), Eng. Geol. 284, 106031. [3] Mancini F. et al. (2018), ESC2018, S29-639: 428429. [4] Luzi L. et al. (2016), Istituto Nazionale di Geofisica e Vulcanologia, Observatories & Research Facilities for European Seismology. [5] Boore D. M. (2003), Pure Appl. Geophys. 160 635–675. [6] Motazedian D. and Atkinson G. M. (2005), Bull. Seismol. Soc. Am. 95 995–1010.

Results of laboratory experimental study of the hydraulic fracture initiation, its propagation and closing, re-fracturing, the fluid pore pressure variations and related acoustic emission (AE) are considered. The experimental setup differs from common equipment designed for testing cores or cubic samples; it is designed for work with samples of disk form with diameter 430 mm and height 66 mm, which allows us to measure the pore pressure distributions along the sample boundary together with passive and active acoustic emission measurements (Fig.1). The experiments were conducted with artificial porous saturated samples made from gypsum-cement mixture in agreement with simulation criteria. The samples were created by filling the pressure chamber with the gypsum-cement-water mixture. After drying, the samples were saturated by gypsum water solution and loaded by three-axial stresses. To produce the fracture, mineral oil was injected with the constant rate 0.3 sm3/sec through the cased borehole. A set of experiments was conducted, in which the main stress axis orientation was changed after the first hydraulic fracture creation. Registration of the change in the amplitude of the waves passing through the fracture allowed to determine the fracture formations, its filling with fluid, the increase in the fracture opening as the injection continued, and the fracture closing after the injection was stopped. It was found that the influence of the fluid pore pressure diffusion from the point of injection is of great significance: the fracturing pressure was several megapascals higher than it should be expected. The fracture closing pressure also occurred to be higher in comparison with the case, when the pressure diffusion is neglected. It was obtained, that the AE source positions are closely related with the fracture position. It is remarkable, that we did not registered any AE outside the fracture. Comparison that fact with the results of the pore pressure measurements allows to suggest, that the pressure increase due to the viscous fluid injection is not enough to induce AE pulses at some distance from the borehole and the fracture. When the injection fluid has the same viscosity as the fluid saturating the sample, the pressure increase is sufficient to induce acoustic emission corresponding to the pore pressure increase.

This year marks the centennial of the American Geophysical Union advancing Earth and space science and 89 years of hydrologic science. The last 100 years have seen science and technology dancing a harmonious and progressively accelerated waltz. Hydroelectric power generation has made widespread electrification possible, while the rise of electronics and the advent of computers have enabled hydrologists to exploit increasingly complex models. Scientists and engineers have conquered space, and now satellite-based products and remotely sensed data have become indispensable inputs for hydrometeorological forecasting. Yet several important elements that have accompanied humanity’s history – nature, culture, and people – have been relegated; and it is only very recently, in the face of modern challenges, that they have attracted substantial attention. The advent of robust, cheap, and low-maintenance sensing equipment provides unprecedented opportunities for data collection, especially in a citizen science context. While citizens have been present throughout the history of scientific practice, developments in sensing technology, data processing and visualization, and the communication of ideas and results, are creating a wide range of new opportunities for public participation in scientific research. Integrating societal knowledge with hydrologic science, however, is not only a task for the 21st century. Historically, many civilizations have developed local water harvesting and management practices that cope with water stress by using ancient and nature-based knowledge. Indeed, indigenous peoples developed solutions that were inspired and supported by nature, and use, or mimic, natural processes to contribute to improved water management and to safeguard their water security. Technological development and knowledge integration also have a more fundamental impact on the way in which hydrologic knowledge advances, how it flows between different actors, how it disrupts power relations, and thus how it influences decisions and policy-making. We envisage that, in the next century, hydrologic science will benefit from co-creating knowledge that emerges from citizens, resonates with nature, and integrates ancient wisdom.

Wildfires are becoming larger and more frequent across much of the US due to a combination of climate change and land use activities. Increasing wildfires have begun to raise concerns about effects on fresh waters, including water quality and other ecosystem services. Despite this, previous research mostly consists of short-term case studies and focuses on streams and rivers rather than lakes and reservoirs (hereafter, lakes). Using the Monitoring Trends in Burn Severity (MTBS) database, we show that 4.5% of lakes ≥ 1 ha in the continental US experienced at least one watershed wildfire from 1984-2016. Interestingly, lake watershed fires are not restricted to the western US. Of all the lower 48 states, Florida, Texas and Kansas were the top 3 states with the most lakes experiencing wildfire, whereas Idaho, Arizona and Nevada were the top 3 states by percentage of lakes in respective states experiencing wildfire. Using the LAGOS-US database, we present new regional-scale findings demonstrating effects of large wildfires on lake water quality. For example, we found a negative correlation between post-fire lake water clarity and the proportion of a lake’s watershed burned in 11 Minnesota and Wisconsin lakes (r = -0.61). We highlight the urgent need for more broad-scale studies that encompass an ecologically diverse set of waterbodies, landscapes and fire regimes, particularly in landscapes in which humans depend on lakes for fresh water. Finally, we emphasize that growing data sources such as MTBS and continental-scale water quality databases (e.g., LAGOS-US) offer prime opportunities for research advances that can help scale up findings from local case studies.

Sea ice plays a crucial role on the ocean and is one of the most sensible indicators of climate change (IPCC 2013). The changing sea ice can be characterized by 4 Essential Climate Variables (ECVs) identified by the World Meteorological Global Organization Climate Observing System implementation plan (WMO Pub No.GCOS-200) : 1) sea ice extent, 2) sea ice concentration, 3) sea ice drift and 4) sea ice thickness. Since the 70ies, these 3 first variables are fairly well observed from space. However, before 2010 and the launch of CryoSat-2, sea ice thickness observations remain sparse and un- homogeneously distributed over time and space. In the Arctic ocean, we will show in this presentation that sea ice thickness time series can be extended to at least 16 years (2002-2017) using Envisat, CryoSat-2 and Sentinel-3 satellites with inter-missions biases calibrated and corrected. Among all potential inter-mission biases, the most impacting is certainly the transition from Low Resolution Mode (LRM) to Synthetic Aperture Radar (SAR) altimetry. This transition is particularly important over sea ice considering that the strong roughness heterogeneity, at basin scale and within the radar footprint, has different signatures in LRM and SAR modes. Here, we will focus on the transition between Envisat and CryoSat-2 common flight period (20010-2012). Results are validated against in situ observations (mooring, airborne, buoys and laser altimetry). This same methodology is applied to produce equivalent long term time series over Antarctica (2002-2017). In the southern ocean, the main difficulties rely on the severe lack of in-situ observations and on the ability to retrieve the snow depth. First results based on the Saral and Cryosat Ka-Ku frequency radar differences will be shown. Finally, we explain how this new global sea ice volume changes will provide new insights on the response to climate change. In particular, the final objective is to revisit the ocean freshwater budget and to provide a new constraint on the land ice melt contribution to sea level rise that is independent from the NASA Gravity Recovery and Climate Experiment measurements.

Botswana is located at the centre of southern Africa, where major tectonic features intersect and interact, e.g., the anomalous topography of the African-superswell, the termination of the East African Rift System, and the boundaries of the cratons and mobile belts. Moreover, Botswana is a major player in the production of critical raw earth materials. Therefore, the study of Botswana's crust and upper mantle gives more insight into the tectonic development of the region and improves our understanding of the distribution of Earth resources and natural hazards. Although novel country-wide geophysical data have been compiled and processed in the last two decades, some unclear and debated hypotheses about important tectonic features and the geodynamics of Botswana from various geophysical studies still exist. This includes the debate about the existence of a buried Maltahohe microcraton in the southwest region, the mechanism of the rifting in the Okavango Rift Zone, and the further extension of the East African Rift System to central Botswana. This research presents a homogenous 3-D electrical model with unprecedented spatial coverage, using a robust 3-D methodological scheme. We used magnetotelluric data from 355 stations throughout Botswana to derive an electrical conductivity model. The result of this research provides straightforward, connected, and precise geologic interpretations about different arguments raised in the literature on the tectonics and structure of the crust and upper mantle beneath Botswana. The model shows interesting features, including the major cratonic blocks, a separate cratonic structure -- Maltahohe microcraton in southwest Botswana, and the mobile belts. Furthermore, the model gives new insight into the Okavango Rift Zone and the extension of the East African Rift System to Botswana. Our results overcome the fragmented nature of the previous studies and the incoherent methodologies and approaches that have led to some misleading or conflicting interpretations.

There has been progress in machine learning (ML) to produce accurate and robust model predictions for hydrologic systems. This progress opens a new opportunity to enhance our fundamental understanding of the underlying physics of a given attribute in the subsurface environment. In order to achieve such understanding through ML in addition to reliable model predictions, we develop a general framework of system identification, named by GPfSI, which provides interpretable models representing system dynamics embedded in data. This approach aims to discover multiple governing differential equations for a target multi-physics system by combining user’s prior knowledge about the system dynamics and a data set of system excitation and responses. In efforts to identify governing equations in the infinite model space in an effective way, one of the machine learning methods, Genetic Programming (GP), is employed. As a stochastic optimization method, GP is utilized to optimize differential equations to a given data set through evolutionary processes. We significantly enhance the effectiveness and computational efficiency of the GP-based identification process, by incorporating a multi-purpose loss function and stochastic sampling into the parallelized fitness test, and bloat control techniques into the evolution process. We demonstrate the proposed framework, GPfSI, against simulated and experimental data sets. In the demonstration case with the simulated data, the reference canonical model, i.e., the advection-dispersion equation (ADE), was successfully identified with a wide range of system characteristics and data noise. In the application to the experimental data from a soil column tracer study, GPfSI provided several nonlinear ADEs that are capable of capturing the anomalous (i.e., non-Fickian) tailing behavior observed in the solute breakthrough data. The inspection of the identified models provides some insights into the underlying physics of non-Fickian transport. Consequently, our results indicate that GPfSI is an effective and robust gray box modeling tool to produce accurate model predictions and enhance our fundamental understanding of hydrologic systems.

Estimating the effect of geomagnetic disturbances on infrastructure is an important problem since they can induce damaging currents in electric power transmission lines. In this study, an array of magnetotelluric (MT) impedance measurements in Alberta and southeastern British Columbia are used to estimate the geoelectric field resulting from a magnetic storm on September 8, 2017. The resulting geoelectric field is compared to the geoelectric field calculated using the more common method involving a piecewise-continuous 1-D conductivity model. The 1-D model assumes horizontal layers, which result in orthogonal induced electric fields while the empirical MT impedance data account for fully 3-D electromagnetic induction. The geoelectric field derived from empirical MT impedance data demonstrates a preferential polarization in southern Alberta, and the geoelectric field magnitude is largest in northeastern Alberta where resistive Canadian Shield outcrops. The induced voltage in the Alberta transmission network is estimated to be ~120 V larger in northeastern Alberta when using the empirical MT impedances compared to the piecewise-continuous 1-D model. Transmission lines oriented northwest-southeast in southern Alberta have voltages which are 10-20% larger when using the MT impedances due to the polarized geoelectric field. As shown with forward modelling tests, the polarization is due to the Southern Alberta British Columbia conductor in the lower crust (20-30 km depth) that is associated with a Proterozoic tectonic suture zone. This forms an important link between ancient tectonic processes and modern-day geoelectric hazards that cannot be modelled with a 1-D analysis.

In upland soils in humid climates, mineral stabilization of organic matter (OM) on millennial scales is often driven by the abundance of poorly crystalline, metastable chemical weathering products. Studies of volcanic ash soils have demonstrated that these metastable materials transform into increasingly crystalline minerals at advanced stages of weathering, so that the overall affinity of mineral surfaces for OM declines with time. However, the abundance of clay-sized (<2 𝜇m diameter) particles tends to increase with weathering, enhancing soil specific surface area (SSA) and potentially compensating for the loss of mineral affinity for OM. As a first step towards understanding the net effects of these simultaneous transformations on OM stabilization, we compared the coverage of SSA by OM in A and B horizons of ash-derived soils sampled along an elevation gradient in Veracruz, Mexico. N2 adsorption isotherms and Brunauer–Emmett–Teller (BET) theory were used to estimate SSA of bulk soil versus samples from which OM had been removed via combustion (muffling) and chemical oxidation (bleaching). In addition to comparing the effectiveness of the OM removal treatments, we characterized the extent to which the treatments altered the mineral matrix and introduced errors into the estimates of mineral SSA. Pore size distribution was estimated via density functional theory as a complement to the BET analysis. N2-accessible SSA ranged from 9 to 105 m2 g-1 after removal of OM, with muffling yielding higher values than bleaching for most samples. The probable loss of SSA associated with mineral transformations (e.g., of Fe oxides) at high temperatures during muffling was evidently offset by the more thorough removal of OM by that treatment. Although SSA tended to increase with weathering status, relative coverage of SSA by OM was relatively consistent across profiles and tended to be greater on average in A horizons (bleaching: 45% SSA covered, muffling: 51%) than in B horizons (bleaching: 28%, muffling: 34%). The apparent lack of OM coverage of SSA in the B horizon of the most weathered soil (0% of 60 m2 g-1 covered) underscores the overall importance of mineral reactivity in determining OM stabilization. Future work will extend these analyses to examine land-use effects on SSA coverage by OM.

Clear air turbulence (CAT) is a serious threat for civil aviation flights. In the years 2009 through 2015, with the support of the European Commission, as a part of the 7th Framework Program, the DELICAT project (DEmonstration of LIdar based Clear Air Turbulence detection) was implemented. In this project, an air-borne lidar was developed and built for an early detection of CAT. In August 2013, flight tests of the lidar were carried out. During the experiments, a large unique data set was collected; a copy of the data set is in the possession of the Obukhov Institute of Atmospheric Physics of Russian Academy of Sciences (IAP RAS). In the proposed project, we propose solving the following problems. We will develop a numerical model of the laser sounding of CAT, considering the effect of the laser beam propagation in a random medium, as well as the aerosol (Mie) and molecular (Rayleigh) scattering. The analysis of the existing observations indicates that, in most cases, the multiple scattering effects are negligible. The will allow us to develop the model on the basis of the multiple phase screen method. This model will produce realizations of the random signal for specific realization of the random refractivity and aerosol distribution fields. A modification of the multiple phase screen method will allow modeling a diverging laser beam. This will also allow modeling of the back-scattering enhancement (BSE). By varying the aerosol composition, it will be possible to model different degree of correlation and intensity ratio in co- and cross-polarization channels. The model of the laser sounding of CAT will help answering the question, whether aerosol is an impeding factor when using the BSE effect. We will develop a realistic model of the observation geometry variations. We will perform the primary processing of the whole available data set of the DELICAT observations. This will allow us to estimate the statistical properties of the measurement noise. We will analyze the DELICAT observations. We will fit the model parameters in order to reproduce, as close as possible, the statistical properties of the observations. This will help answering the questions, how accurately and timely it is possible to detect CAT parameters using two types of lidar systems: 1) system with two polarization channels, and 2) system based on the BSE effect.

On this poster we explore how well global HYbrid Coordinate Ocean Model (HYCOM) simulations predict (semidiurnal) internal tides and their decay. We explore two important factors that govern the internal tide predictability: model resolution (8 km vs. 4 km) and wave drag. We validate these simulations with internal-tide sea-surface height amplitudes from altimetry, surface-tide dissipation rates estimated from an altimetry-constrained model, finestructure and microstructure dissipation rates, and modal-conversion rates computed from analytical models. To compare HYCOM to various altimetry data sets, we derive a spatially varying correction factor that accounts for the effect of time series duration on non-stationarity. We perform tidal energy balances and decompose the M2 internal tides into vertical modes.

A novel system of Monitoring Vibrations and Perturbations in the Lithosphere, Atmosphere, and Ionosphere (MVP-LAI) was established in Leshan, Sichuan, China in 2021. The system comprises 14 distinct instruments with 22 devices continuously monitoring changes in 14 geophysical parameters ranged between a few meter underground to ~350 km in altitude to examine and/or expose causal mechanisms of the LAI couplings. Note that the ground-based GNSS receivers of the system receive the electromagnetic signals from the geostationary BeiDou satellites that retrieve the total electron content over certain locations 24 × 7 without montage. Significant amplifications of TEC perturbations appear during the night since mid-May 2021. The M6.4 Yunnan and M7.4 Qinghai earthquakes occurred in Mainland China on 21-22 May 2021. The amplifications are related with the two earthquakes due to that the associated TEC perturbations reside over the epicenters. The resident TEC perturbations and ground vibrations close to the epicenters share a frequency of ~0.005 Hz, which can be attributed to the resonant coupling between the lithosphere and ionosphere.

In the near-future, new space telescopes like JWST, LUVOIR, and HabEx will begin attempting to explore the properties of atmospheres of potentially habitable planets. This will require a significant amount of time and resources for even a single planet, which makes it essential to prioritize observations by those most-likely to have detectable life. Here we present a statistical method to estimate the probabilities that specific exoplanets have been continuously in the habitable zone of their host stars for more than 2 billion years, the approximate time it took life on Earth to significantly increase the oxygen content of the atmosphere. We introduce the use of statistics of an ensemble of 3D planetary general circulation models to estimate these probabilities, replacing prior 1D model estimates.

When Apollo returned the first moonrocks, a major surprise was that the lunar highlands are built of a single mineral - feldspar. Feldspar crystals floating to the top of a moon-magma ocean can explain this composition. If accepted as a key early stage in lunar evolution, it is a logical leap to infer that Earth must have had a similar – or larger – magma ocean during its early evolution. (The gravitational impact energy per unit mass that is released during a planetesimal’s accretion scales as GM/R.) The nagging problem with the inference that Earth passed through an early magma-ocean stage is that the oldest rocks on Earth show no direct signs of a magma ocean. Instead the petrology of the oldest preserved Earth rocks shows clear evidence that repeated events of small to medium degrees of partial melting and melt extraction, as opposed to pervasive fractional crystallization, has been the modus operandi of terrestrial differentiation. The big difficulty is how to effectively ‘remix’ the products of an early terrestrial magma ocean back into the quasi-uniform ‘primordial’ pyrolite/peridotite silicate lithology from which oceanic and continental crust are thought to have evolved by partial melting events. Here I propose that a partially molten silicate body is actually highly resistant to the formation of a magma ocean. Jing and Karato (2012)’s experiments imply that a silicate melt should absorb much more impact shock-energy than either a silicate solid or an iron solid/melt. In this case, impact energy will be heterogeneously added into the growing proto-Earth, with silicate partial melts being shock-compression-heated to their vaporization temperature before their surrounding silicate solids heat to their melting point. The growing partially molten planetary surface will tend to ‘explode’ during impact events, with each impact-induced-explosion using a relatively small mass of vaporized silicate partial melt to fragment and rework much larger masses of cold, shock-fractured overlying ‘lithosphere’. This explosive-armour-like mode for silicate planetary accretion will strongly resist the magma ocean-mode of planetary differentiation. A magma ocean would only tend to form in the planetary body created from the accreting debris ring of a giant impact event, a Moon.

The Stratospheric Aerosol and Gas Experiment operating on the International Space Station (SAGE III/ISS) is an occultation instrument that retrieves aerosol extinction and ozone, water vapor, and other trace gas concentrations. Water vapor in the stratosphere plays a significant role in ozone depletion and global temperature regulation making it an important species to monitor. The new SAGE III/ISS instrument provides high quality, vertically resolved profiles of water vapor throughout the stratosphere and upper troposphere. A discussion is presented on the sensitivity of the SAGE III/ISS instrument to water vapor and provide an early evaluation of the retrieved profiles.

In principle, a goal of any regional seismic network (RSN) is simple - detect and review seismicity in the network’s region of interest. Vigorous aftershock sequences however present a unique challenge to an RSN’s mission in that they can overwhelm automated real-time and analyst-driven post-processing systems. This inundation with seismicity can the lead to earthquake catalogs that are incomplete and erroneous in the area around the aftershock sequence. In response to this challenge, this abstract explores integrating machine learning as a tool to expedite the University of Utah Seismogram Station’s (UUSS)’s response to the September, 2017 Soda Springs event in southeast Idaho. In the months following the event the UUSS was able to locate over 1000 aftershocks and was catalog complete to approximately 2.5 M_L. Owing to the fact that a temporary deployment of 6 six-channel and 2 strong-motion instruments were deployed to the area shortly after the event, it is anticipated that many more high-quality locations can be obtained without resorting to template matching. Therefore, it is our goal to attempt to recover the existing UUSS catalog with machine learning enabled workflows that can produce analyst-grade picks for location and subsequent magnitude estimation. Should this be successful then the anticipated consequence is that analysts can quickly screen and approve more events and by extension lower the network’s magnitude completeness during the aftershock sequence.

Chapter 27 of the 4th U.S. National Climate Assessment, Volume 2, assesses climate impacts, future risks, and adaptation in Hawai‘i and the U.S.-Affiliated Pacific Islands. The author team collaboratively developed the chapter’s Key Messages and narrative. Webinars and an informal survey of stakeholders informed the selection of focal sectors. To be inclusive of the vast region and expertise, the authors convened six half-day workshops on key sectors, including remote participation from experts in the U.S. Affiliated Pacific Islands. In all, the chapter involved more than 60 technical contributors. Authors reviewed major areas of risk and new understanding since the last national assessment, including on issues such as: (1) reliable and safe water supplies, (2) marine and terrestrial ecosystem health, (3) sea level rise and coastal impacts, (4) impacts on community livelihoods and well-being, including Indigenous peoples. Under these climate-related challenges to island sustainability, diverse groups are coming together to combine forward-looking policies with adaptation strategies. An integrated theme throughout the chapter is that early intervention can lower the economic, environmental, and social and cultural costs from a changing climate.

Twenty years ago, Andy Majda and Rupert Klein developed a multiscale asymptotic theory of tropical dynamics which they named IPESD. IPESD is a linear, forced, dynamical theory on the tropical synoptic scales coupled to a linear, slower, weak temperature gradient theory on the tropical planetary scales. The two scales interact with one another through upscale fluxes of momentum and temperature (the Reynolds stresses) and downscale advection from the planetary scale (developed by B. and Majda as the IMMD theory in 2010). Majda and myself used these theories in the following years to develop a multiscale kinematic model of the Madden Julian oscillation. Criticisms of this theory have missed the essential fact that the mathematics of the asymptotic analysis are inexorable, and verified by observation - the forcing is stronger on small scales and weaker on large scales; that’s all that is really needed to derive IMMD. In our MJO models, we showed that, in order to capture the westerly wind burst structure of the MJO, it was sufficient to force the planetary scales with momentum fluxes (Reynolds stresses) from westward tilted convective structures on the synoptic scales. Left unanswered was the cause of the westward tilted convection, though westward tilts had been observed repeatedly in MJO observing campaigns. The non-traditional terms in the Coriolis force (NCT) seem to provide an excellent candidate for westward tilts, but it is well known that these terms are too weak on scales greater than the mesoscale to affect the dynamics. However, the multiscale theories provide a distinct route for the NCT to affect the planetary scales - through upscale fluxes of momentum. We will show analytically that the net-NCT affects tropical convection by generating zero force in the vertical direction, a westward velocity field in regions of upward flow, and a recirculation in regions of downward flow, around a convective structure. The upscale fluxes from these circulations drive the vertical/westward tilt that was necessary to generate the westerly wind burst in the Majda/Biello models of the MJO. We will also show how these results, westward tilt and the westerly wind burst, can be created in simple laboratory experiments. We sincerely hope that Andy would have been gratified by these results, and excited by our experiment.