It is still a challenge to understand the mangrove dynamics and their response to the environmental forces. The assessment of the mangrove dynamics can be obtained by observing the development of its biophysical properties. This observation will provide insights into the processes at the plot level and landscape level. In this research, the assessment has been conducted by integrating Unmanned Aerial Vehicle (UAV) photogrammetry with the Structure from Motion (SfM) method and multiple satellite imagery sources. The objectives are to retrieve the mangrove biophysical properties based on two periods of UAV observation (2019 and 2021) and estimate the extent and the age-height relationship of the mangrove forests for twelve years. The analysis resulted in an accurate individual tree structure and mangrove age distribution. We integrated UAV-based very high-resolution 3D point clouds and the classified mangrove extent based on the combinations of satellite imagery from four satellites (Landsat 7-8 and Sentinel 1-2). The point clouds were processed by noise removal, ground classification, height normalisation, and generating the Canopy Height Model (CHM) to detect the individual tree height and location. Google Earth Engine has been used to perform the mangrove classification by way of four vegetation indices, i.e., Normalised Difference Index, Normalised Difference Moisture Index, Enhanced Vegetation Index, and Soil-Adjusted Vegetation Index. The off-the-shelve UAV-based surface model had a total error of 0.06m compared to the ground control points, and the root mean square error of the individual tree was 0.23m. GEE’s mangrove classification resulted in the three-monthly mangrove extent map —an advantage over the commonly annual mangrove extent map. The UAV-derived height information and satellite-based mangrove age class were integrated to retrieve the relationship of mangrove height dependent on the stand age. We observed the seasonal pattern of mangrove expansion. The mangroves area receded during the transition from dry to wet season and regrow during the wet to dry season. The general trend is the expansion of the mangroves with the high-low seasonal signal that is likely related to the mangrove’s response to sediment deposition and freshwater.

One model for formation of obsidian pyroclasts suggests that they form through sintering of ash particles on volcanic conduit walls, which are subsequently torn out and entrained in the gas-particle dispersion out of the erupting vent. Here, we investigate microlite abundances and textures in obsidian pyroclasts in order to determine the time required to produce adequate numbers of microlites, and hence the pyroclasts themselves. We measured microlite number densities (MNDs) and microlite and vesicle orientations in obsidian pyroclasts in tephra deposits from the 1340 A.D. North Mono eruption. MNDs increase with decreasing dissolved H2O concentrations. Also, microlite spatial orientations become less aligned and differ more from vesicle orientations with decreasing dissolved H2O concentrations. MNDs increase from the second layer (P2) through the final layer (P10). To investigate timescales required to replicate MNDs in the North Mono obsidian, we performed time, temperature and pressure-controlled experiments with rhyolitic glass from the same eruption. MNDs in our experiments initially increase with decreasing pressure (50-35 MPa), then decrease as pressure decreases further(35-10 MPa). MNDs in obsidian from layers P2-P10 were replicated in ~7 hours or less. Based on these observations we propose a model where during the initial phase of the North Mono eruption most obsidian formed close to the magmatic fragmentation depth, equilibrated for short time periods (< 7 hours) and were then erupted out of the volcanic vent. These obsidian clasts have lower MNDs than subsequent phases, and microlites are well aligned with each other and with vesicles, reflecting their short residence time in the conduit, higher dissolved H2O contents, and lower viscosities. During later phases of the North Mono eruption obsidian formed at various depths in the conduit, equilibrating for longer periods of time (≤ ~7 hours) before being erupted out of the vent or sintering together with other clasts and equilibrating at shallower depths before being erupted. These obsidian clasts have higher MNDs than earlier phases of the eruption, and microlites are not well aligned with each other or with vesicles, reflecting their variable residence times in the volcanic vent, lower dissolved H2O contents, and higher viscosities.

OCO-2, launched in 2014, uses reflected solar spectra and other retrieved geophysical variables to estimate (“retrieve”) the column averaged dry air mole fraction of CO2, termed XCO2. A critical issue in satellite estimates of trace greenhouse gasses and remote sensing at large is the error distribution of an estimated target variable which arises from instrument artifacts as well as the under-determined nature of the retrieval of the quantities of interest. A large portion of the error is often incurred during inference from measurement of retrieved physical variables. These residual errors are typically corrected using ground truth observations of the target variable or some other truth proxy. Previous studies used multilinear regression to model the error distribution with a few covariates from the retrieved state vector, sometimes termed “features.” This presentation will cover the bias correction of XCO2 error attributed to retrieved covariates with a novel approach utilizing explainable Machine Learning methods (XAI) on simulated sounding retrievals from GeoCarb. Utilization of non-linear models (Zhou, Grassotti 2020) or models that can capture non-linearity implicitly (Lorente et al. 2021) have been shown to improve on linear methods in operation. Our approach uses a gradient boosted decision tree ensemble method, XGBoost, that captures non-linear relations between input features and the target variable. XGBoost also incorporates regularization to prevent overfitting, while also remaining resilient to noise and large outliers – a feature missing from other ensemble DT methods. Decision Tree based models provide inherent feature importance that allows for high interpretability. We also approach post training analysis with model agnostic, explainable methods (XAI). XAI methods allow for rigorous insight into the causes of a model’s decision (Gilpin et al. 2018). By applying these techniques, we will demonstrate our approach provides reduced residual errors relative to the operational method as well as yielding an uncertainty estimate in bias corrected XCO2, which is currently not treated separately from the posterior uncertainty estimate derived from the retrieval algorithm.

Hydrogen cyanide (HCN) is a widely available molecule in planetary and interplanetary environments. It has been observed that the polymerization of HCN can lead to the formation of nucleobases and proteins (Matthews & Minard 2006). Thus, HCN and its reactivity are considered to be very important for prebiotic chemistry. Our evaluation covers several molecules and oligomers, most of which have been discussed in the literature (Ruiz-Bermejo et al., 2021), and ranks them based on thermodynamic preference. In our study, we compute the relative energies of a series of HCN-derived materials relative to HCN in liquid water. We perform an automated search with semi-empirical methods to extract the lowest energy conformers for each compound. Our work relies on density functional theory (DFT) calculations with thermal corrections coupled to an implicit solvation model to better emulate the polymerization environments. These methodologies allow us to discuss the impact of our results at relevant environments such as that of Saturn’s Moon Titan or the early Earth conditions. The most stable HCN-derived material in our set is the nucleobase adenine, computed to lie ~26 kcal mol-1 below HCN in a water solution. Our enumeration of thermodynamically plausible reaction products and the reaction routes for the abiotic formation of organic macromolecules starting from simple units of HCN offers extensive insights into the chemical and the physical limitations of suspected key prebiotic processes (Sandström & Rahm 2021). 1. C. N. Matthews, R. D. Minard, Faraday Discuss. 2006, 133, 393. 2. M. Ruiz-Bermejo, J. L. de la Fuente, C. Pérez-Fernández, E. Mateo-Martí, Processes 2021, 9, 597. 3. H. Sandström, M. Rahm, ACS Earth Space Chem. 2021, 5, 2152–2159.

Simple neutral particle detectors consisting of organic scintillators, sensitive photodetectors, and readout systems have been used to great effect in space- and Earth-based science for observing gamma rays and particle radiation from solar weather, astrophysical phenomena, and even lightning storms on Earth. The calibration of simple gamma ray detectors was improved through kernel density estimation (KDE) in a user-friendly Jupyter notebook running a Python script. When calibrating organic particle detectors, a gamma ray source is applied and the distribution of raw voltages produced by the detector are represented in a histogram including a distinct Compton edge. The location of the edge in the histogram can be associated with the energy of the gamma ray source to convert the histogram of voltage measurements into a representation of the gamma ray energies interacting with the detector. The process of estimating the location of the edge on a histogram of real measurements with imperfect resolution is often done by hand or with a half gaussian fit, but we propose an alternative technique where KDE of the raw voltages replaces the histogram. Using KDE, Gaussian kernels are built up to a representation of the underlying energy distribution which can be easily numerically differentiated. The minimum of the modified distribution identifies the location of the Compton edge, regardless of the resolution of the detector. To demonstrate the technique on a model of a Compton edge, we calculated the theoretical Klein-Nashina Compton distribution of Cesium-137 gamma ray interactions, created a model of the edge with a piecewise 2nd order polynomial, and convolved the piecewise function with a Gaussian to approximate the experimental response. The response was numerically differentiated and the location of the minimum was consistent with the energy of the Compton edge, as the inflection point of the approximated Gaussian distribution occurs at the Compton edge. We also demonstrate the technique with data from a MEGAlib simulation of a simple block particle detector. For projects with repeated adjustment and testing of particle detectors, this method should improve consistency and accuracy of calibration while reducing analysis time.

The Bransfield Strait is a semi enclosed region located between the Antarctic Peninsula and the South Shetland Islands (SSI), where the Bransfield Current (BC) is a relatively warm baroclinic jet (0-250 m) flowing northeastward along the southern slope of the SSI. Recent studies have shown that the BC propagates as a buoyant gravity current, recirculating around the north-eastern tip of the islands while shedding an anticyclonic eddy. However, most previous works are based on summertime measurements and a more comprehensive spatio-temporal view of the regional circulation is still lacking. In this study we provide the first seasonal description of the BC based on an extensive dataset of direct velocity measurements. These measurements were routinely collected along ship tracks from 275 cruises between 1999 and 2014. Seasonally, the horizontal structure of the BC flowing as a coastal jet appears more prominent during spring and summer, when its pathway extends along the island slopes over 180 km at velocities up to 45 cm/s, from Deception Island towards King George Island. During these seasons, the BC is consistently narrower at the beginning of its path (15-20 km wide), and wider before starting its recirculation around the SSI (30 km wide). Through autumn, this pattern is also apparent but less intense, especially south off Livingston-Robert Islands, where subsurface velocities (150 m) are lower at about 10-15 cm/s. The scarcity of winter data confirms the existence of a relatively strong coastal jet with mean velocities about 34 cm/s at least south off Nelson Island. Vertically, the BC also displays a distinctive pattern. At the wake of the islands, the core of the current flows hugging the island slopes with velocities about 35 cm/s at 150 m. Differently, when located at channels between islands, the core of the current migrates offshore flowing at 30-45 cm/s. In terms of zonal volume transport (0-250 m), our estimates indicate that the BC transports about 0.85, 0.93, 0.90 and 1.01 Sv from spring to winter, respectively, at the location where all seasons are covered by data (south off Nelson Island). These results support the BC is a recurrent feature of the circulation in Bransfield Strait, flowing northeastward all along the southern slope of the SSI not only during summer but also during spring and autumn.

The extent to which terrestrial weather below 30 km in altitude can influence the dynamics and mean state of the thermosphere (ca., 100-500 km) is a fascinating discovery of the last two decades or so. Waves that are excited by deep convection in the tropical troposphere and propagate vertically into the thermosphere are responsible for much of this influence. Tropospheric convection associated with the Madden JulianOscillation(MJO), the dominant mode of intra-seasonal variability in tropical convection and circulation, has been known to modulate the intensity of upward propagating gravity waves and Kelvin waves. An MJO impact on tides was already proposed over two decades ago, but only recent gains in satellite observational capabilities allows one to quantify their effect from observations. Previous work by Gasperini et al. [2017a] demonstrate that a 90-day oscillation in tropospheric convection during 2009-2010 is imprinted on both thermospheric mean winds and the eastward propagating wavenumber 3 diurnal (DE3) tidal amplitudes observed by the GOCE and CHAMP satellites and modeled with the TIME-GCM. In a follow-on modeling-based study, Gasperini at al. [2020] present statistical evidence for a strong connection (+/-12%) between the phase of the tropospheric MJO and the amplitudes of the thermospheric DE3 and 3-day ultra-fast Kelvin wave (UFKW), two of the most prominent and well-established waves from the tropical wave spectrum that preferentially propagate into the thermosphere. These recent studies demonstrate that strong coupling between the troposphere and the thermosphere occurs on intra-seasonal timescales, raising important questions that have implications for the whole atmosphere system. In this work, we present evidence for a strong quasi-60 day oscillation in GOLD column-integrated O/N2 and Swarm-C total mass density during 2018-2019. A similar and concurrent oscillation is observed in the DE3 and SE2 tidal amplitudes derived from SD/WACCM-X. Spectral analysis of OLR reveals a similar oscillation in tropical tropospheric convection that is shown to be eastward propagating with s=-1 and is thus consistent with an MJO event.

The Brine Availability Test in Salt (BATS) is a field heater test being conducted in the bedded salt formation at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM. BATS is focused on exploring brine availability as part of a wider investigation into the disposal of heat-generating radioactive waste in salt. Brine has the potential to transport radionuclides, corrode waste forms and packages, reduce criticality, and pressurize porosity to resist closure through salt creep. In BATS, two identical arrays of horizontal boreholes were constructed in an experimental drift, 650 m below ground at WIPP. In each array, 13 observational boreholes were installed around a central borehole. One of the two array was heated, and the other array was left at ambient temperature. During the first heating phase (January to March 2020), the 750 W heater ran for 4 weeks. The central boreholes included dry nitrogen gas circulation behind a packer. The gas stream removed moisture which flowed into the boreholes. The gas stream was analyzed in-drift for stable water isotopes using a cavity ringdown spectrometer and gas composition using a quadrupole mass spectrometer. The satellite boreholes in each array included numerous thermocouples, electrical resistivity tomography (ERT) electrodes, acoustic emissions (AE) piezoelectric transducers, distributed temperature and strain fiber optics, and a cement seal exposure tests (both sorel and fly-ash base concretes). Cores from the boreholes were X-ray CT imaged for mineralogical and fracture distribution. We present an overview of the first phase of the test, and illustrate key data collected during the first heating cycle. Follow-on tests in the same boreholes will include gas and liquid tracer tests and additional packer-based gas permeability testing. New boreholes for the next round of BATS in 2021 are being planned.

Peatlands are becoming recognized as important carbon sequestration centers where, through restoration projects, peatlands may stop being considered as carbon sources and become carbon neutral or possibly carbon negative. Restoration projects require a knowledge of intra-peat variation across these, sometimes, vast areas. The integration of multidimensional geophysical tools, digital elevation models and satellite remote sensing products combined with modern data analytic techniques may provide a rapid means of accessing variations over broad spatial scale. In this study an airborne radiometric survey, being flown nationally over the Republic of Ireland, is shown to be able to delineate potential management zones within an industrial raised peat bog. Radiometric data is particularly suited to peat studies as they are sensitive to water content. Peat, as a mostly organic material, acts as a low signal environment where variations in the signal are linked to intra-peat variation of either depth or water content. This study uses an unsupervised, self-organizing map clustering methodology to group the radiometric signal into three zones interpreted as 1) the edge of the bog where peat layer is thinning and there is influence on the radiometric signal from non-peat soils outside of the bog, 2) the normal peat conditions where depth and saturation appear as a relative constant in the radiometric response and 3) areas where the peat is either thinner, drier, or potentially somewhat mineralised. The addition of other data layers such as elevation, slope and satellite imagery may help better define these zones and a ground geophysical survey is planned to test the results of this study. The definition of such potential management zones could aid any restoration project in the initial stages or act as a baseline study to monitor changes to the peatland during and after a restoration project is complete.

Being at the interface of the geosphere, the biosphere, and the atmosphere makes the soil a particularly challenging object. Nevertheless, its importance in ecological and environmental domains should encourage researchers to make use of new technologies, like 3D printing, to improve their comprehension of soils. With 3D printing we can build up objects by adding materials layer-by-layer based on a three-dimensional model, producing almost any geometrically complex shape or feature in a wide range of materials. Here we present the major challenges and opportunities of 3D printing for its application into soil science. We show that despite the remarkable achievements in 3D printing development during the past few years, it is still under-used in the field of soil science. Besides the 3D printing technology uses considering the soil as a source of mineral raw materials, or as the basis for the development of technical infrastructure, new researches highlight the functioning of the soil itself as an ecological compartment. Indeed, one of the most important challenges for the application of 3D printing in this area is the accurate modeling and replication of the soil structure and composition. This would require 3D-printed objects to be made of biocompatible yet chemically and mechanically stable materials manufactured under controlled conditions, which can mimic the many interactions occurring at this scale. Having 3D-printed objects with strict and controlled composition and structure could help academics and researchers to conduct reproducible experiments and gain a better understanding of the parameters controlling soil ecology and functioning. This opens a new way to broader utilization of 3D printing in soil science in the near future.

Urban expansion is a global trend primarily determined by overpopulation, particularly in developing countries like India. The pattern and boundary of urban expansion could be observed and modelled on a Spatio-temporal dimension in the Asan watershed, situated in western Doon Valley, Uttarakhand, India. The specific objectives of the present study are: 1) Monitoring Land Use Land Cover (LULC) change detection and its impact on the hydrological regime of the watershed, 2) Generation of urban growth pattern map to identify the urban expansion along with the directions and distance from the watershed centroid. To achieve the objectives, the four LULC maps of different years are generated through Landsat and LISS-IV dataset from 1980 to 2016. The eight classified classes of LULC includes: build-up (urban and rural), cropland, fallow land, plantation, evergreen needle leaf forest, deciduous broadleaf forest, mixed forest, and water bodies. The LULC change analysis concludes that the built-up area continuously expanding at an alarming rate, nearly four folds in the last 36 years. The major areal portion of cropland and plantation are converted into build-up at a faster rate after 1995 whereas the areal extent of water bodies are also reduced. Based on monitoring of urban growth, the wind rose tool revealed that the southwest direction is the dominant direction of the urban expansion till 1980 and 1980-1995 which contribute 48% and 47.61% respectively of the total urban area of the watershed. However, in the period 1995-2008 and 2008-2016, the eastern direction is predominant, which contribute 36.44% and 35.27% respectively from the total urban areal expansion. This reflects a situation where the eastern direction is expected to dominate in the next years. Consequences of urban expansion create pressure on the into the watershed which leads to degradation of natural resources, forest environment and hydrological elements of the watershed.

SIHLA (Spatial/Spectral Imaging of Heliospheric Lyman Alpha pronounced as ‘Scylla’ [e.g. Homer, Odyssey, ~675-725 BCE] investigates fundamental physical processes that determine the interaction of the Sun with the interstellar medium (ISM); the Sun with the Earth; and the Sun with comets and their subsequent evolution. To accomplish these goals, SIHLA studies the shape of the heliosphere and maps the solar wind in 3D; characterizes changes in Earth’s extended upper atmosphere (the hydrogen ‘geocorona’); discovers new comets and tracks the composition changes of new and known ones as they pass near the Sun. SIHLA is a NASA Mission of Opportunity that has just completed its Phase A study (the Concept Study Report or CSR). At the time of the writing of this abstract NASA has not decided whether to fly this small satellite mission or its competitor (GLIDE: PI Prof. Lara Waldrop). SIHLA observes the ion-neutral interactions of hydrogen, the universe’s most abundant element, from the edge of the solar system to the Earth, to understand the fundamental properties that shaped our own home planet Earth and the heliosphere. From its L1 vantage point, well outside the Earth’s obscuring geocoronal hydrogen cloud, SIHLA maps the entire sky using a flight-proven, compact, far ultraviolet (FUV) hyperspectral imager with a Hydrogen Absorption Cell (HAC). The hyperspectral scanning imaging spectrograph (SIS) in combination with the spacecraft roll, creates 4 maps >87% of the sky each day, at essentially monochromatic lines over the entire FUV band (115 to 180nm) at every point in the scan. During half of these daily sky maps, the hydrogen absorption cell (HAC) provides a 0.001nm notch rejection filter for the H Lyman a. Using the HAC, SIHLA builds up the lineshape profile of the H Lyman a emissions over the course of a year. SIHLA’s SIS/HAC combination enables us to image the result of the ion-neutral interactions in the heliosheath, 100 AU away, in the lowest energy, highest density, part of the neutral atom spectrum – H atoms with energies below 10eV. The novel aspects of SIHLA are the scope of the science done within a MoO budget. The SIHLA projected costs were below the $75M cap with a 31.3% reserve for Phase B-D. The re-purposing of a spectrographic that was part of the DMSP SSUSI line (a copy was flown and NASA TIMED/GUVI and as NASA NEAR/NIS). Risk is extremely low in this Class-D mission with all major elements at least at TRL6 at this time. SIHLA has a high potential for discovery. We expect that we will 1) First detection of the hot H atoms produced directly from the ion-neutral interactions at the heliopause; 2) First detection of structures in Interplanetary Medium H emission, 3) First detection of response of the Earth’s extended (out to lunar orbit) geocorona to solar/geomagnetic drivers, 4) New UV-bright comets as they enter the inner solar system. SIHLA is a hyperspectral imager; at every point in the sky SIHLA obtains the entire FUV spectrum.

Tectonic information available from remote seismometers is compromised by uncertainties in epicenter and depth, which often prevent earthquakes being associated with faults observable in morphologic data. Here we show that careful study of regional recordings can achieve reasonable position and, for the larger events, also depth estimates. We illustrate this with swarms totallying 90 earthquakes of 3.6 mb to 5.5 Mw recorded at coastal stations of the Brazilian Seismographic Network, GSN, GEOSCOPE and Cape Verdes. Seismicity occured in 4 swarms, firstly in 2012 with 7 events in the valley floor and eastern wall near the ridge-transform intersection (4.05º-4.2ºN). Next, five events occurred in 2014, with three in the inner floor (4.8º-4.9ºN) and two under the valley wall (4.7º-4.8ºN). A 70-earthquake swarm in 2016 occurred in the 4.4º-4.8ºN valley floor, in both walls and floor, involving slip on different faults. The last 8 events in 2019 were located outside the median valley near a volcanic seamount. We estimated focal depths of the strongest events with Mw > 5.4 using waveform modeling and focal mechanims reported by the Global Centroid-Moment-Tensor Project. Our best estimated hypocenters lie 5-8 km beneath the seafloor, in keeping with maximum depths typically found with OBSs on the MAR. In contrast, deeper events (10 km) have been found in an OBS experiment around an active detachment fault elsewhere. Multibeam sonar data from the area do reveal a detachment fault surface (“megamullion”), but it ends 10-15 km from the median valley floor, suggesting that it is probably inactive. Although our uncertainties still do not allow the event depths to be discriminated from 10 km, our best estimates are more compatible with shallower normal faulting. Over time, repeating this exercise with many such datasets and comparing with morphologic data should help to resolve the incidence of deeper ruptures associated with detachment faults.

Abstract In order to decipher complex subsurface structures, various seismic imaging techniques have been developed. Full Waveform Inversion (FWI) is one of the most sophisticated approaches in the new generation of seismic imaging algorithms for 2D/3D Earth modeling. An effective implementation of FWI requires a good initial model and intensive computations, among other challenges. To address these challenges, we developed a new FWI scheme, where we perform just a few local inversions under the assumption that the layers present only small lateral variations. We then upscale the local inversions to reconstruct 3D media. This approach also includes Source Signature inversion and does not require an initial model. The algorithm is based on the exact analytical solution of the Navier-Lame equation for a visco-elastic multi-layer model. This solution is represented in the form of Fourier-Bessel integrals, and performs forward modeling calculations about 106 – 107 times faster than conventional finite differences (FD) algorithms. It is free from various numerical artifacts inherent to FD methods, and allows modeling of all known types of seismic waves. The solution also indicates numerous unknown waves in various layered systems (some of the waves are practically impossible to reproduce numerically for the thin layers, using the grids, typical for 3D modeling). The comparison of the exact solution with 3D FDTD results shows excellent agreement. Here we applied this approach to stratified media with small lateral variations (the Earth, consisting of the inclined multi-layer structures). The feasibility of the method was analyzed using traces from synthetic seismograms for the Marmousi model, which were simulated by the 3D elastic SW4 code. A few sources with surrounding geophones were chosen. At the first stage we invert the traces from each geophone to the local stratum under the source, deciphering thicknesses, densities and P,S-wave velocities for each layer. At the second stage we identify the layer boundaries’ slopes and reconstruct the full 3D model. For the Marmousi model we obtained an accurate image down to 2.3 km deep, after which lateral variations were excessive. This result demonstrates that a new FWI scheme exploiting separate inversions, can be applied successfully to the reconstruction of 3D media.

This study provides a new, detailed, and fully three-dimensional structural interpretation of the active convergent plate boundary beneath the outer Nankai accretionary wedge offshore Kii Peninsula in SW Japan. Structural interpretation was done using the 12 by 56 km 2006 Kumano 3D seismic reflection volume, with the goal of providing new insights on the structural, temporal, and spatial evolution of the shallow plate boundary megathrust. Results of the structural analysis suggest three decollements with complex, three-dimensional geometries that have played a role in constructing the outer Nankai wedge in the study area, only one of which shows recent activity. Based on comparison to sandbox models and the presence of a modern, partially subducted seamount, their development and evolution are linked to past and present subduction of oceanic crust with signicant relief, including the Paleo-Zenisu Ridge east of the study area. Other characteristic features of the outer wedge likely developed from the effects of basement relief subduction as well, including the low velocity zone, along-strike variation of imbricate thrusts, prominent along-strike ridges across the margin, and several laterally discontinuous strike-slip faults. Evidence that the outer wedge evolved through several phases of basement relief subduction has strong implications for the mechanical properties of the deeper, seismogenic portions of the megathrust. Other studies suggest subduction of basement relief correlate with low slip-decit rates, VLFs, and slow slip, and may act as a barrier to coseismic rupture. Therefore, the results of this study can be applied to convergent margins with similar tectonic settings around the world to better understand the link between basement relief subduction, decollement and wedge evolution, and seismogenic behavior.

The 2020 COVID-19 pandemic provided a unique opportunity to sample atmospheric gases during a period of very low industrial/human activity. Over 1000 Whole Air Samples were collected in over 30 cities and towns across the United States from April through July 2020 as part of the NASA Student Airborne Research Program (SARP). Sample locations leveraged the geographic distribution across the United States of the undergraduate and graduate students, faculty, and NASA personnel associated with the internship program (44 people total). Each person collected approximately 24 air samples in their city/town with the goal of characterizing local emissions with time during the pandemic. Samples were collected in 2-Liter stainless steel evacuated canisters at approximately 2 meters above ground level. The canisters were shipped to the Rowland/Blake Laboratory at the University of California Irvine and analyzed for methane, carbon dioxide, carbon monoxide, non-methane hydrocarbons, and halocarbons using the gas chromatographic system described in Colman et al. (2001) and Barletta et al. (2002). Initial samples collected in April coincided with the peak of stay-at-home/social distancing orders across most of the United States while samples collected later in the spring and early summer reflect the easing of these measures in most locations. Overall trends in emissions with time across the United States during the pandemic (in several large metro areas as well as rural locations) will be discussed.

For the first time, we have developed a wind atlas to determine the onshore wind power potential of each U.S. state. Previously, Geographical Information System (GIS)-based wind atlases have been developed that include multiple parameters for identifying sites suitable for wind energy development. Such atlases contain data and exclusions for houses, roads, and protected areas. They also include restrictions for sensitive military and political land areas, terrain not suitable for wind power generation, national parks, and nature preserves. However, such atlases have yet to be developed for the U.S. or its individual states. The purpose of this study is to create a wind atlas to calculate the onshore wind power potential of each U.S. state, accounting thoroughly for exclusions. We also develop a GIS portal that can be used by stakeholders in the wind industry to plan future wind project developments and to reduce the uncertainty and risks in the early stage of site hunting. To accomplish these goals, we use Envision Energy’s EnScope wind atlas tool. The tool accounts for Wind Resources Restrictions (social, environmental, and technical characteristics that can delay, impede, or stop wind power projects) Regulations (national and regional distance requirements to infrastructure, buildings, and protected areas) Wind Turbine Information (dimensions, footprint, and energy output of a modern onshore wind turbine) With the resulting atlas, we determine the maximum available land for developing wind energy in the U.S., the total wind energy potential in the U.S., and an indication of how that potential compares with what is needed to power the entire U.S. with wind’s share of a 100% clean, renewable energy system for all energy purposes in 2050.

CHALLENGES Submarine channels, erosional features on the world’s continental margins, are of great interest as they prove to be a prolific reservoir around Gulf of Mexico, offshore Brazil and western coast of Africa. The main challenge is to highlight the channels and extract them as 3D objects from 3D-seismic data, as conventional approach to delineate and map submarine channels in current data set is difficult owing to presence of subtle thin submarine channels. METHODOLOGY This 3D-seismic survey from Poseidon 3D prospect of the Browse Basin spans an area of 4070 km with an orientation of 310° North. Submarine channels are present in the Late Cretaceous Woolaston formation. Generalized Spectral Decomposition and Sweetness attributes have been used in this study to identify submarine channels. Generalized Spectral Decomposition attribute volumes were generated at different frequencies to identify some of the resolved channels. The Sweetness attribute, on the other hand, was helpful in distinguishing other channels based on the amplitude envelope and instantaneous frequency. The Sweetness attribute, after blending with Generalized Spectral Decomposition attribute, was used for Geobody (3-D objects) extraction from the seismic data. Significant enhancement of channels and suppressing background features was accomplished by controlling the opacity of the volume. It was followed by extraction and editing of Geobodies. RESULT AND CONCLUSION The current data set in Browse basin has up to 10 submarine channels in Cretaceous, most of them being subtle and difficult to map in 3D-seismic data. An alternate methodology to characterize submarine channels by using Generalized Spectral Decomposition and Sweetness attribute helped to mitigate the challenge. Generalized Spectral Decomposition attribute could delineate some submarine channels that got tuned at specific frequencies. The Sweetness attribute was helpful in distinguishing other channels using the amplitude envelope and instantaneous frequency. Further, the process of extracting submarine channels as ‘Geobodies’ from seismic volume, proved to be very valuable as it can be directly used for volumetric estimation of prospects. Thus, the methodology discussed in this study can be used as a reference to characterize and quantify submarine channels.